RHAMM, CD44 EXPRESSION AND ERK ACTIVATION ARE LINKED IN MALIGNANT HUMAN BREAST CANCER
CELLS AND ARE ASSOCIATED WlTH CELL MOTlLlTY
Frouz Frozan Paiwand
A thesis submitted in conformity with the requirements for the degree of Master of Science
Graduate Department of Laboratory Medicine and Pathobiology University of Toronto
O Copyright by Frouz Frozan Paiwand 1999
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I dedicate this Master's thesis to my rnother, who is the source of my
inspiration, and to rny family for their never-ending love and support.
RHAMM, CD44 Expression and ERK Activation are Linked in
Human Breast Cancer Cells and are Associated with Cell
Motility
Frouz Frozan Paiwand
Master of Science, 1999
Department of Laboratory Medicine and Pathobiology
University of Toronto
ABSTRACT We assessed CD44 RHAMM, erk, and ras expression in human breast cancer ce11
lines that Vary as xenografts in nude mice. Compared to MCF-7 cells, MDA-MB-231
cells expressed higher levels of CD44, RHAMM, erk, and ras, showed higher levels of
ce11 surface RHAMM, and displayed greater motility that was reduced by anti-RHAMM
or anti-CD44 antibodies, or by a MEK inhibitor. These inhibitors also reduced the
motility of mutant active ras-transfected MCF-IOA cells which, relative to wild-type ras
or empty vector transfected cells, were more motile and had increased RHAMM, CD44
and activated erk expression. MDA-MB-23 1 cells and mutant ras-transfected MCF-1OA
cells demonstrated nuclear CO-localization of RHAMM and erk, whereas RHAMM and
CD44 CO-localized to perinuclear regions or to ce11 processes. Co-immunoprecipitation of
RHAMM with both CD44 and erk was also observed. These resuIts suggest that
RHAMM and CD44 may coordinate signaling through the ras-MAP kinase pathway to
control ce11 motility.
iii
This thesis could not have been completed without the help and support of
numerous coworkers, colleagues, and friends.
1 am most thanldùl to my supervisor and mentor, Dr. Eva Turley, who not only
provided me with the material resources, technical training, and scientific guidance
needed to undertake the studies in which 1 participated, but who was also a source of
encouragement far me to continuously srrive for excellence.
1 am also indebted to al1 the members of Dr. Turley's research group, past and
present. My thanks extend especially to Lisa CoUis, Rene Hamson, JingBo A, Shwin
Zhang and Judy Edwards - with whorn I shared formative experiences as a graduate
student - for their advice and support on issues both scientific and personal. For their
friendship, stimulating discussions, and knowledge, L would also Iike to thank ail the
other students, postdoctoral fellows, and associates who are the present members of the
Iaboratory.
1 would like to express my sincere thanks to the members of my thesis advisory
cornmittee - Drs. Marlene Rabinovitch and Gabrielle Boulianne - for their invaluable
guidance on the direction of my research project and maintainhg the standard of the
M.Sc. degree at the University of Toronto. As well, 1 thank the other members of my
original examination committee - Dr. Fred Keeley and Dr. Howard Lipshitz - for their
advice in regard to my previous research project.
To my mother and sister Leeza, and to al1 the members of my farnily, 1 owe
gratitude for their continuous patience and support throughout the years of my univeaity
education. It is to them that 1 dedicate this thesis.
Foremost among my fiiends deserving acknowledgement is Michael Levesque,
whose daily encouragement and advice nourished me in mcuIt times and inspired me to
wnte this thesis in order to progress frorn M u a t e studies to the educational.
professional, and personal oppoctunities that Lie beyond.
Finally, 1 would like to acknowledge the financial support of Hyal Pharrnaceutical
Corporation, Mississauga, Ontario, Canada.
The studies described in this thesis were performed at the Department of
Cardiovascular Research at The Hospital for Sick Children, under the aegis of the
Graduate Department of Laboratory Medicine and Pathobiology at the University of
Toronto, during the years 1 997- 1999.
DEDICATION .................................. .., ...................................... ABSTRACT .............................0................................................
ACKNOWLEDGEMENTS .............................................................
................................................................ TABLE OF CONTENTS
LIST OF TABLES ........................................................................ LIST OF FIGURES ................................. -... ..............................
.......................................................... LIST OF ABBREVIATIONS
CEIAPTER
.......................... ................................. 1 . INTRODUCTION .... ............................. 1 . 1 . Extracellular Matrix and Tumorigenesis
.. ..................... . 1 1.1. Tumorigenesis and Metastasis .... 1 . 1.2. HA and Tumorigenesis .......................................
.................... 1.2. The HA Binding Receptors: RHAMM and CD44
1.2.3. Domains of CD44 Related to Ce11 Motility and Celi Cycle Control .............................................
1.2.5. RHAMM ........................................................ ...... .......... 1 . 2 . 6 . RHAMM Isoforms ................... ..,. ..
1.2.7. Domains of RHAMM Related to Ce11 Motility and Ce11 Cycle Control .........................................
1.3. Tumor Progression is Associated with Elevated Expression of CD44 and RHAMM ....................... .,. ... ... ..............
................. 1.4. Hypothesis. Rationale. and Objectives of this Smdy 23
I . MATERIALS AND METKODS .......................................... 25
II . 1 . Cell Culture ......................... ,., .....~.O........................ 26
II . 2 . Antibodies ..................... ,. .... ... ..~........................... 27
II . 3 . Western Irnmunoblotting and Immunopr~cipitation ................ 28
. ......... II . 4 Time-lapse Cinemicrography .. ... .. .......................... 30
II. 5. Flow Cytometry (FACS) . . . . . . . . . . - . . . . . . . . . . . - . - - - - . . . . . . . . . . .. . . . .. . . . II. 6. Immunofluorescence S taining . . . . . . . . . . . . - . . - . . . - - .. . -. . . . . . . . .. . . . .- -
III. RESULTS .......................................................................... III. 1. Antibodies Specifically Detect RHAMM .. . . . . . - - - . . . . . . . . . . . . . . . . . .. LII. 2. CeU Surface RHAMM Expression Varies with Time on the
Surface of Human Breast Cancer Cells . . . . . . . . . . . . .. . . . . . . . . . . -. . . . . . III. 3. Breast Cancer CeUs Express Several RHAMM bofonns . . . ... . ... III. 4. RHAMM Overexpression is Associated with the Presence
of Mutant Active ras .. . . . . . . . . .. . .. . . . -. - - -. -. .... -. . . . . . . . . . . . . .- -. .-.. III. 5. RIIAMM Overexpression in MDA-MB-23 1, MCF-7, or
MCF- 1 OA CelIs Correlates with the Overexpression of ras, Presence of Active erk, and with High LRvels of CD44 .. . . .. .. . .. ..
III. 6. RHAMM Co-distributes with erk and CD44 in Breast Cancer CeIls . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . - - - . . . . . . . . -. . . . . . . . . -. . . . -..
III. 7. RHAMM Co-irnmunoprecipitates with erk and CD44 in MDA-MB-23 1, MCF-7, and in ras-transfected Breast Epithelial Cells . . . . . . . . - . . . -. . . . . . .. - . - - - -. . -. -. . . - . . - . - - - . . . . . . . . . . . . . . .
m. 8. RHAMM and CD44 are Required for the Locomotion of MDA-MB-23 Ceils and Ceils Transfected with Mutant Active ras . . . . . . . . . . . . . . . . . . . . -. . - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -. - . -. . . . . . .
III. 9. Figures of Chapter III . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . ....... . -. . -. . . . . . - N. DISCUSSION . - . . . . . . . . . . . . . . . . . . . . . . . . . - .. - . - . . - . . - -. - - - - - . - - - . - . . . . . . . . . . . . . . . . .
N. 1.
N. 2.
W. 3.
W. 4.
IV. 5.
IV. 6.
IV. 7.
Ras and raderk Signaling Cascade in Breast Cancer Development . . . . . . . . . . . . . . . . . . . .. . . . . .... . . . . ....... . . . . . . . . . . . . . . . . . 69
CD44 and RHAMM, Co-receptors that Mediate Tumor Ce11 Motility through the ras/MAP Kinase Pathway . .. .. . . . . . . . .. . .. 73 RHAMM and CD44 Expression are Linked to ras Overexpression and erk Activation in Breast Cancer Cells and Breast Epithelial Cells Transfected with Mutant Active ras . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. - . . . . . . . . . . . . . . . . . . . . . . . . . 80
RHAMM CO-associates with erk in MDA-MB-23 1 Cells and MCF-1OA Cells Transfected with Mutant Active ras . . . . . . . . . . 8 1
RHAMM Co-associates with CD44 in Breast Cancer Cells and Breast Epitheliai CeiIs Transfected with Mutant Active ras . . . . . . .. 83
A Mode1 of HA and its Receptoa in raslerk Signaling and Breas t Cancer Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Future Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . - . . . . . . . . . . . . . . 88
vii
V. REF'ERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
VI. APPENDLX . ..... ..*... ..**.. ..-... .... .-... ...,...... . . . . . . . . 11 1
The DrosophUn RHAMM Homologue
LIST OF TABLES CHAPTER 1.
Table 1.1. HA Binding Pro teins . . . . . . . . . . . . . . . . . . . - . . . - - - .. . . . . . . . . . . . 8
CaAPTER IV.
Table N. 1. Characteristics of Human Breast Epithelial Cell Lines . . ... 76
LIST OF FIGURES
Fig. 1.1.
Fig. 1.2.
Fig. 1.3.
....... The Basic Repeating Disaccharide Sequence in HA
.......... ........................ The Family of Hyaladherins .,
CD44 Exon Structure and RNA Splicing in Nonnal and ................................................. Diseased Tissue
............ Role of CD44 in Ce11 Motility and Proliferation Fig. 1.4.
Fig. 1.5.
Fig. 1.6.
CHAPTER III.
Fig. III. 1.
.............................................. RHAMM Isofonns
.................. RHAMM7s Predicted Secondary S tnicture
Confirmation of the Specificities of RHAMM Antibodies-2 and -3 by Immunoblot Analysis ...............
Fig. ïïï. 2. Detection of RHAMM Expression on the Surface of MDA-MB-23 1 and MCF-7 Cells by FACS Analysis .......
Fig. III. 3. Western Immunoblot Analyses of RHAMM Expression ........................... in MDA-MB-23 1 and MCF-7 Cells
Fig. III. 4. Western Imrnunoblot Analyses of RHAMM Expression ............................. in ras-transfected MCF- 1 OA Cells
Western Immunoblot Analyses of Active erk, H-ras, and CD44 Expression in MDA-MB-23 1 and MCF-7 Cells .....
Fig. III. S.
Fig. III. 6. Western Immunoblot Analyses of Active erk, H-ras, and ....... CD44 Expression in ras-transfected MCF- IOA Cells
Fig. III. 7. Confocal Microscopic Analysis of RHAMM, erk and CD44 Expression in MDA-MB-23 I and MCF-7 Cells ..... Confocal Microscopic Analysis of RHAMM, erk and CD44 Expression in ras-transfected MCF- IOA Cells .......
Fig. III. 8.
Fig. III. 9. Confocal Microscopic Analysis of CD44 and ras Expression in Breast Cancer Cell Lines and in ras-transfsted Breast
.................................................... Epithelial Cells
Fig. m. 10. Fig. m. Il.
Co-immunoprecipitation of RHAMM, erk, and CD44 .. .. .. Time-lapse Cinernicrography of MDA-MB-23 1 Cells
........................ and ras-transfected MCF- 1OA Cells ... CEIAPTER N.
Fig. Ne 1.
Fig. IV. 2.
............................ Ras regufates a Cascade of Kinases
A Mode1 of HA and its Receptors in the raderk
Signaiing Paîhway . . . . . . . . . . . . . . . . . . . . . - - - - -. - - - - . -......... . . . ......... . ......... . . . 87
LIST OF ABBREVIATIONS
Ab
BSA
CD44s
CD44v
cDNA
DMEM
DMSO
ECL
ECM
EDTA
EGF
ER
ERK
ERM
FACS
FBS
FGF
GABP
GAG
GAP
GD1
GPI
GST
GTP
HA
HAS
HBSS
HRP
IgG
Antibody
Bovine serum albumin
Standard CD44 isofonn
Variant CD44 isofom(s)
Complementary DNA
Dulbecco' s modified eagle' s medium
Dimethyl suifoxide
Enhanced chemilurninescence
Extracellular matrix
Ethylenediaminetetraacetate
Epidermai growth factor
Estrogen receptor
Extraceiluiar signal regulated protein kinase
Ezrin, radixin, and moesin proteins
Flow cytometry
Fetal bovine semm
Fibroblast growth factor
Hyaluronan binding protein(s)
Gl ycosaminogl ycan
GTPase activating protein
GDP dissociation inhibitor
Glycosylphophatidyl inositol
Glutathione S-transferase
Guanine triphosphate
Hyaluronan, hyaluronic acid, hyaluronate
Hyaluronan synthase
Hank's balanced salt solution
Horseradish peroxidase
lmmunoglobulin
xii
MABP
KDa
mAb
MAP
MAPK
MEK
MHC
NK
OD
PAGE
PCR
PDGF
4,5PrP2
PKC
PML
PMSF
PTK
RACE
RHAMM
RHAMMs(m or h)
RHAMM(A 1 -5)
RIPA
RT-PCR
SCD44
SCLC
SDS
SH3
TBST
TGF
Tris
m c
Intracelluiar hyaluronic acid binding protein
Kilocialton
Monoclonal antibody
Mitogen activated protein
Mitogen activated protein kinase
MAPWERK kinase
Major histocompatibility complex
Natural killer (cells)
Opticai density
Polyacrylamide gel electrophoresis
Pol ymerase c hain reaction
Platelet-derived growth factor
4,s Phosphatidylinositol phosphate 2
Protein kinase C
Polymorphonuclear leukocytes
Phenylmethylsulfonyl fluoride
Protein tyrosine kinase
Rapid amplification of cDNA ends
Receptor for hyaluronan mediated motility
Standard murine or human RHAMM
RHAMM exons 1-5 deleted
Radioimmunoprecipitation assay buffer
Reverse transcriptase PCR
Soluble CD44 isofonn(s)
Smail-ce11 lung cancer
Sodium dodecyl sulphate
Src homology 3
Tris-buffered saline containing Tween 20
Turnor growth factor
Tris (hydroxymethy1)-aminomethane
Trisrhodamine-isoth yiocyanate
xiii
CHAPTER I
INTRODUCTION
1.1. Extraceiluiar Mntrix and Tumorigenesis
1.1.1. Tumorigenesis and Metastasis
Breast cancer wiil stnke one of every eight women in her Iifetime in North
Amenca. Although the last 20 years have produced several advances in the areas of early
breast cancer detection and therapeutic management, the incidence of this disease has
increased and rnortality has not decreased. It is likely that thtough a clearer
understanding of the molecular mechanismis underlying breast cancer development,
progression, and metastasis we will eventually be able to alter these numbers
significantly. There are many changes at the genetic level that are associated with bteast
cancer. They include the overexpression, remangement, or amplification of normal
cellular genes and proto-oncogenes, mutations that result in activation of oncogenes or
inactivation of suppressor genes, and loss of genetic material that presumably represents
the loss of suppressor genes.
Cancer is a multi-step process with several sequential cellular alterations occurring
before complete maiignant transformation results. A current mode1 for multistage
carcinogenesis was developed by Vogelstein for colon cancer (Vogelstein et al., 1988;
Fearon and Vogelstein, 1990; Fearon et al., 1990), a number of genetic and phenotypic
changes have however been identified in breast cancer (Dickson and Lippman, 1997;
Walker et al., 1997). For instance, suppressor gene expression may be lost from loci on at
least three genes such as pS3, BRCA1&2, and RB1 and mutation, activation, or
overexpression of many oncogenes such as c-erbB1, cerB/HEWneu, ras, c-myc and
Met cornmonly occur during the development of human colon cancer (Dickson and
Lippman, 1997; Waiker et al., 1997). These accumulated genetic alterations result in the
progression of colon cancer from non-cancerous adenoma to invasive colon cancer. It is
apparent that a single alteration of one gene does not result in cancer, and it seems iikely
that for each cancer either a different combination of progressive alterations are involved
or the same alterations lead to differing phenotypes depending on target tissue specificity.
The route to breast cancer is not as well mapped as that to colon cancer, but by studying
the genetic changes occming at each level of breast ceIl growth scientists are beginning
to identify important participants in this process.
It is metastases fiom the primary tumor, as opposed to the original tumor, which
usually kiIl the patient, and local regional lymph nodes are the most common and earliest
sites of metastasis of breast tumors. Many features of cancer including tumor ceil
motility, increased ECM degradation, changes of tumor ce11 adhesion, proliferation and
angiogenesis are required to create a metastatic deposit (Mareel et al., 1993; Weiss, 1994;
Levine et al., 1995; Price et al., 1997).
A variety of molecules have been shown to be important for the metastatic
properties of tumor cells. These include autocrine production of cell adhesion and
motility factors, growth factors and growth hormone receptors, interferons and
components of ECM [e-g. hyaluronan (HA) ] (Turley et al., 199 1 ; Turley, 1992; Levine
et al., 1995; Kantor and Zetter, 1996; Pnce et al., 1997). Collectively these factors
regulate the ability of cancer cells to first detach from the primary tumor mass, invade the
l ymphatic s ystem, then spread throughout the bldstream (Tuszynski et al., 1996).
Tumor ce11 motility is required for the metastatic cells to intravasate, extravasate, and
travel to target sites (Fidler et al., 1978; Liotta, 1986; Koop et al., 1996; Price et al.,
1997). Endothelial ce11 migration is also required for tumor anchored angiogenesis
(Folkman et al., 1998). In addition to the above factors, degradation of the extracellular
matrix (ECM), which depends on the balance of activated proteinases, matrix
metalloproteinases (MMPs), and theu naturdly occurring inhibitors in the tissue, is
likewise important for the metastatic process (Torre and Fulco, 1996; Andreasen et al.,
1997; Price et al., 1997).
1.1.2. HA and Tumorigenesis
Hyaluronan (also called hyaluronic acid, h yaluronate, or HA), a high-molecular-
weight glycosaminoglycan, is implicated in various physiological functions, including
maintenance of matrix structure, water homeostasis and ce11 proliferation, differentiation
and locomotion (Laurent and Fraser, 1992; Turley et al., 1992; Savani et al., 1995b;
Catterail et al., 1995; Knudson, 1996; Collis et al., 1998). HA is a negatively charged,
unbranched, high molecular weight single long-chah polysaccharide consisting of
repeating disaccharide units, D-glucuro~c acid and N-acetyl-D-glucosamine, linked by
B 1-3 and 1-4 glycosidic Linkages (Fige Ie 1.). In solution, HA presents as an expanded
stiffened helical prirnary configuration and exhibits multiple hydrophiIic and
hydrophobic sites within each molecule. Its secondas, structures, where hydrophobic
and hydrophilic segments altemate, is formed by intramolecular hydrogen bonds (Scott et
al., 1989). This altemate occurrence of clustered hydrophobic and hydrophilic segments
in HA structure provides the basis for the interactions between HA and the plasma
membrane and its receptors, and also for HA to aggregate (Scott, 1989, 1992).
Fig. 1.1. The Basic Repeating Disaccharide Sequence in HA
The role of HA in turnorigenesis has k e n suggested by a number of experimental
findings both in vitro and in vivo (Victor et al., 1999). For instance, HA promotes
mammary carcinoma ce11 locomotion in vitro (Tanabe et al., 1993; Torre and Fulco,
1993; Auvinen et al., 1997), and HA production has been shown to correlate with the
invasive and metastatic capability of both mouse mammary carcinoma ceIl lines and
some human breast cancer ce11 lines (Angeiio et al., 1982; Sommers et al., 1994; Wang et
al., 1996; Naoke et al., 1999). hcreased expression of HA has been correlated with poor
differentiation both in adenocarcinorna ce11 lines and in tumor stroma of ductal breast
cancer (Auvinen et al., 1997; Ropponen et al., 1998). Higher levels of HA have been
found in the sera of breast cancer patients, and these levels correlate with breast cancer
progression and response to chemotherapy (Classen et al., 1995). Furthemore, HA was
found to increase in tumors, paaicularly in invasive areas, in cornparison with normal
tissues (Bertrand et al., 1992, 1997; Itano et al., 1999).
via a complex site known as the iink module (Kohda et al., 1996). RHAMM is a
prototype of ceU-associated h y aladherins that occur at mu1 tiple cellular loci, including the
ce11 surface, cytoplasm and nucleus and are characterized by the lack of a trammembrane
signal sequence or iink module (Table 1. 1.). Rather, HA binds to hyaladhenns via
simple motifs of basic amino acids (Yang et al., 1994; Kohda et al., 1996). The
mechanisms by which these proteins are released and bound to the cell surface are
unknown.
Fig. 1.2. The Family of Hyaiaâherins
RHAMM
Table 1.1. HA Binding Proteias
I 1 1
RHAMM 1 none 1 major 1 none apparent
HYALADHERINS
cdc37
P68
1 1 I
VersicadHyaIumnectin 1 major I present, minor I none apparent
LINa MODULE CONTRIBUTION
none
none
HBP (hepatocyte binding protein) CD44
I pp
major 1 pment, minor 1 none apparent 1 1 1 1
Neurocan 1 major 1 present, minor I none apparent
[B(X7)Bl nfwllF CONTRIBUTION
major
major
not de termineci
major
1 I 1
Brevican I major I present, minor I none apparent
COVALENT LINgAGE
none apparent
none apparent
1 1 I Link protein I major I present, minor I none apparent
not determined none apparent
present, minor 1 none apparent
Fibrinogen
The binding mechanism and affinities of the hyaladherins to hyaluronan via the h i c module, smaii basic amho acidic motifs, or covalent linkages. P P ~ W P ~ ~ et al., 1999
Trypsin inhibitor
1.2. The H A Binding Receptors: RHAMM and CD44
not determined
Both RHAMM and CD44 are encoded as single genes @alchau et al., 1980;
none
Gunthert et al., 199 1; Ghaffari et al., 1995, Entwistle et al.; 1995; Wang et al., 1996;
not detennined
Ponta et al., 1998; Fieber et al., 1999), but occur as multiple protein foms due to
none apparent
presen t but importance not determined
extensive alternative RNA splicing and pst-translational modification.
major
1.2.1. CD44
CD44 was first described as a ce11 surface molecule of T-lymphocytes,
granulocytes, and cortical thymocytes (Kohda et al., 1996), rediscovered as the
phagocytic glycoprotein-1 (Pgp-1) (Mackay ei al., 1988) and GP90Hemies (Goldstein et
ai, 1989), and later identifid as a widely-expressed protein which functions as a major
receptor for HA (UnderIùll et al., 1987; A d o et al., IWO). CD44 is a multifimctional
receptor involved in cellcell and cell-ECM adhesion, i.e. cell motility, tmcking, lymph
node homing, lymphocyte activation, presentation of chemokines and growth factors to
traveling cells, and transmission of these growth signals (LesIey et al., 1993). As well,
CD44 participates in the endocytic uptake and intracellular degradation of HA (Culty et
al., 1994; Hua et al., 1993), and in the transmission of signals mediating hematopoiesis
and apoptosis (Ayroldi et al., 1995) that are relevant to wound repair and tumor
progression.
CD44 ligands other than HA include the ECM components collagen 1 and N
(Wayner et al., 1987), fibronectin (Jalkanen and Jalkanen, 1992), laminin (Radotra et al.,
1994), and the chondroitin sulfate modified invariant chah of class II major
histocompatibility complex (MHC) (Naujokas et al., 1 993), mucosal addressin (Picker et
al,, 1989), serglycin (Toyama et al., 1995) and osteopontin (Weber et al., 1996).
Cons ti tutivel y, the molecule is predominantl y expressed in regions of active ce11 growth
(Mackay et al,, 1994), and is, notably, highly expressed in skin (Tammi et al., 1988), and
in metastatic breast tumor cells (Culty et al., 1994)-
1.2.2. Structure of CD44
Sequence conservation of CD44 between rat, mouse, horse, dog, cow, hamster,
baboon, and human exceeds 7 0 8 (Naor et al., 1997). The human CD44 gene contains 50-
60 kb of genornic DNA and consists of at least 20 known exons (Screaton et al., 1992,
Ponta et al., 1998). Exons 1 to 16 encode the extracellular domain of the protein, exon 18
Exon:
Full Length
CD44v of keratinocytes
Standard (CD44s) long tail Standard (CD44s) short tail
Distribution: u
O P O P P 0 0 0 0 0 0 0 0 0 P 0 I l - human keratinocytes
O Q Q P D O O O O O O O O O O O Q Q O O
Phyriological Role
-apical ectodermal ndge
-lymphocyte homing -ceIl migration -immune response -HA receptor -tumor progression
Pige 1.3 CD44 exon structure and RNA aplicing in normal and diaeared tiaaue. The figure dao shows known tiaaue distribution and potentirl physiologicrl roles. The leader peptide (LP), transmembnne domain (TM) and cytoplmmic tail (CT) portion8 are indicated The rhaded exon 10 is believeâ to be important in conferring invasive ibilitiea in tranaformed cella. Modified From: Paiwand et al., 1999.
encodes a shoa transmembrane domain, and exons 19 and 20 encode the cytoplasmic
domain (Fig. 1. 3.). Exon 5a to 14 are altematively spliced, leading to a number of
different potential isoforms with tremendous variability in the sequence of their
extracellular domain (Tolg et al., 1993). Exons 19 and 20 are also altematively spiiceâ,
leading to two potential cytoplasmic tails (Lokeshwar et al., 1991). Post-translational
modification by N-glycosylation (Mackay et al., 1988, Bartoiazzi et al., 1996), 0-
giycosyiation (Dasgupa et al., 1996, Bennett et al., 1995) and glycosaminoglycanation
with heparin sulfate (Jackson et al., 1995) and chondroitin sulfate (Sleeman et al., 1997)
create additional structural and îùnctional diversity. In totd, there are 20 known isoforms
of different molecular sizes (85-230 kDa) (Naor et a[., 1994). Several experimental
studies suggest that expression of the 85 kDa C D 4 4 (standard isoform), promotes tumor
progression (S y et al., 199 1 ; Hart et al., 1994).
1.2.3. Domaias of CD44 Related to CeIi Motility and Cell Cycle Control
A key domain relevant to ce11 cycle control and motility mediated by CD44 is the
HA binding domain. This domain of CD44 is homologous to the HA binding structure
recently characterized in link protein by NMR (Fig. 1.3. and Table 1. 1.) (Bajorath et al.,
1998). Interestingly, mutation of key basic amino acids within this structure which
resemble RHAMM HA binding sites (Yang et al., 1994) block the ability of CD44 to
sustain proliferation (Bajorath et al., 1998) but have little affect on HA binding, in
contrast to RHAMM, where mutation of these basic amino acids ablates HA binding
(Hyman et al., 1991; Yang et al., 1994). The solution structure of the link module from
human TSG-6 consists of two alpha helices and two anti-parallei beta sheets arranged
around a large hydmphobic core (Kohda et aL, 1996)- Jhterestingly, not a11 CD44-
expressing cells are able to bind HA, but this property can be acquired or can oçcur
transiently (Hyman et al., 199 1). The abiiity of HA to bind to CD44 is regulated by both
protein conformation, rather iike integrin activation, and by glycosylation patterns. Thus,
CD44 can be stîmuIated to bind HA by phorbol esters, anti-CD44 antibodies, or
deglycosylation (Zheng et al., 1995). Blocking anti-CD44 mAbs studies suggest that
topography of the CD44 epitopes and their orientation toward the HA binding site
determine the ability of antibodies to interfere with HA binding (Lokeshwar et al., 199 1,
Galandrini et al., 1993). Clustering of CD44 proteins, which is dependent upon
cytoskeletal proteins, also seems important to its ability to bind HA (Galandrini et al.,
1993). Certain cells (including some B and T ce11 lines) appear constitutively able to bind
HA. However, further studies are required to define the molecular mechanisms that result
in -/KA interactions as well as to assess the impact that these interactions have on
ce11 behavior relevant to tumorigenesis.
1.2.4. CD44 Signaüng
SignaLing through CD44 involves protein tyrosine kinase (PTK), transcription
factor, and cytoskeletal players. This diversification of signaling is not surprishg given
the multiple effects CD44 has on cells. For instance, substrate-attached cells such as
fibroblasts and keratinocytes use HA/CD44 interactions for ce11 adhesion and motility, as
well as proliferation and HA metabolism. in white cells, HNCD44 interactions are
required for lymphocyte homing and activation by cytokines during infiltration into
tissues. However, the s i p a l h g pathways that are responsible for these effects are only
beginning to be understood.
In T and B cells, NK cells, PMLs and macrophages, HA-bound CD44 stimulates
protein tyrosine phosphorylation, calcium infiux and gene activation (Naujokas et al.,
1993; Galandrini et aL, 1996; Pericle et al., 1996). Blocking monoclonal CD44 antibody
studies indicate that HNCD44 interactions are important for cytotoxic effector functions
in these cells, as well as for ceii proliferation and cytokine secretion which are responses
that are key to tumorigenesis (Webb et al., 1990; Gaiandrini et al., 1993; Pericle et al.,
1996). The cytoplasmic domain of CD44 binds to active Lck and Fyn kinases within
protein-nch GPI islands in T celis and endothelial ceils (Funaro et al., 1994; Iïangumaran
et al., 1998), and these islands appear to be necessary for CD44 to generate a protein
tyrosine kinase signal. In both substrate-attached cells and in lymphocytes, CD44 also
participates in the transmission of growth factor-mediated signals (Naor et al., 1991;
Bourguignon et al., 1993; Sommer et al., 1995; Taher et al., 1996). CD44 is also required
for signaling through growth factor receptors such as her2neu (Bourguignon et al., 1997)
(Fig. 1.4.)
CD44 appears to modiw signais available to the ce11 at least in part by regulating
the structure of the actin cytoskeleton via interactions between the cytoplasmic domain of
CD44 and actin binding proteins. These interactions appear to be dynamically regulated
and result from modifications of the CD44 intracellular domain, including altemate
splicing of variant exons, PKC-mediated phosphorylation, acylation by acyl-tramferase,
palrnitoylation, and GTP binding (Naor et al., 1997). Part of the ability of CD44 to
regulate ce11 motility is due to its direct binding to ERM proteins, namely ezrin, radixin,
and moesin (Tsukita et al., 1994, Hirao et al., 1996). ERM proteins are thought to control
the distribution of other adhesion molecules on the ce11 surface and to link actin to the
plasma membrane, especially in ceIl surface projections (Vaheri et al., 1997). h o and
colleagues (Hirao et al., 1996) have provided strong evidence that CD44 functions within
a signaling cascade downstream of Rho. Rho belongs to the family of srnail GTPases,
including ras, rac, and cdc42 that regulate important actin-relatecl events (Takaishi et al.,
1993; Hotchin et al., 1996). This group speculates thai activated Rho causes an
upregulation of PIP-5 h a s e leading to increased ce11 membrane bound 4,s-PIP2 levels
which then promotes CD44ERM complex formation. CD44 may further regulate the
Rho-GDP dissociation inhibitor (GD0 as it tightly binds to the CDWERM complex. It
is presently unclear, however, whether Rho-GD1 recmits Rho to the plasma membrane to
be activated or sequestered (Araki et al., 1990; Tsukita et al., 1994; Takai et al., 1995).
Fig. 1.4. Role of CD44 in Ceii Motility and ProiiTecation
From: Kalish et al,, 1999 1 1 Prolifcmtioii Motil ity & Invasion
RHAMM is member of a group of cell-associated hyaladherins that occur at
several cellular loci and thaî perform multiple functions in regulating cell motility and the
ce11 cycle (Turley et al., 1982, 1994; Mobapatra et al., 1996; Toole et al., 1997; Assmann
et al., 1998; Hofmann et al., 1998; Wang et al., 1998)- For instance, ceii surface forms of
RHAMM are transiently expressed in most ceus but are nevertheless key to regulating
ce11 motility as detennined by anthdy blocking expenments (Boudreau et ai., 1991;
Hardwick et al., 1992; Samuel et al., 1993; Hall et al., 1994, 1995; Pilarski et al., 1994;
Turley et al., 1994; Nagy et al., 1998; Savani et al., 199Sa; 199%; Masellis-Smith et al.,
1996; Delpech et al., 1997; Zhang et al., 1998). Intracellular foms of this class of
hyaladherins, including RHAMM, bind to and chaperone signaling molecuies involved in
regulating ce11 cycle and cell motility (Fig. 1.2.) (Grarnmatikakis et al., 1995, Masellis et
al., 1996; Kimura et al., 1997). These types of hyaladherins may also perform functions
within the nucleus. Such hyaladherins typically lack a link module for binding HA but
rather utilize short sequences encodhg basic amino acid motifs (Table 1.1.) (Yang et ai-,
1994) which are required for ce11 motility and proliferation (Samuel et al., 1993; Sherman
et al., 1994). Even though they are present on the ceil surface (Samuel et al., 1993;
Sherman et al., 1994; Grarnmatikakis et al., 1995; Kimura et al., 1997; Bajorath et al.,
1998; Crainie et al., 1999) this cIass of hyaladherins is also characterized by an absence
of both signal sequences and transmernbrane domains. Therefore, the moiecular basis for
their subcellular distribution is not yet clear. Based upon their modular and dynamic
subcetlular location and the different mechanisms by which they bind to HA, these
proteins likely regulaie cell motility and the ceU cycle in a manner that is fundamentally
distinct from the more well characterked HA receptor, CD44
RHAMM was originally isolated fiom supernatant media of nonconfluent
embryonic chick heart fibroblasts (TurIey et al., 1992). Subsequently. it was found
intracellularly and on the ceil surface (Hardwick et al., 1992; Hall et al., 1994, 1995;
Zhang et al., 1998; Masellis-Smith et al., 1996; Crainie et al., 1999). T t has emerged as a
key regulator of HA-mediated motility and cytoskeletal remodeiing (Entwistle et ai.,
1996). Since HA has been considered to act at the surface to regulate ce11 function, most
studies have focused on the functions of surface-associated RHAMM and this fonn of
RHAMM has been shown to play a role in growth factor responses (Samuel et al., 1993;
Zhang et al., 1998), mocility (Turley et al., 1994; Masellis-Smith et al., 2996; Toole et
al., 1997) and ce11 cycle (Mohapatra et al., 1996). Since, as noted above, RHAMM's
location at the ce11 surface is often dynamic and transient, in particular decreasing rapidly
after plating (Samuel et al., 1993; Zhang et al., 1998), it may function to initiate events
reIevant to ce11 motility, uniilce CD44 which may sustain this cellular function. Severai
recent reports showing an absence of ce11 surface RHAMM (Teder et al., 1997; Assmann
ef al., 1998; Hofinann et al., 1998; Weiss et al., 1998) underscore the transient nature of
this protein and emphasize the need for careful timed analyses to detect expression.
1.2.6. REAMM Isoforms
Two murine RHAMM cDNAs were originally isolated from fibroblasts
(Entwistle et al., 1995; Hofmann et al., 1998), both of which contained i n - h e start and
upstream stop codons and therefore appeared to represent full-length cDNA. Later,
isotation of a human RHAMM cDNA, which was longer than these mutine RHAMM
transcripts in its 5' terminus, was isolated and has been cautiously designated the fuii-
length standard fonn of RHAMM (Wang et al., 1996). The sequence of this human
cDNA was recently confirmed (Assmann et al., 1998) and a murine homologue of this
RHAMM form has been reported (Hofmann et al., 1998; Fieber et al., 1999).
The standard RHAMM mRNA transcript encodes the largest intraceUular
RIHAMM protein, 85 kDa (human) and 95 kDa (murine), that has been designated
standard RHAMM, (Fig. 1. 5.). Evidence is accumulating for the existence of multiple
alternative spliced variants of the standard fom, (Fig. 1.5.) (Wang et al., 1996; Assmann
et al., 1998; Hofmann et al., 1998; Crainie et al., 1999). This includes the presence of
multiple RNA vanscripts detected via primer extension, 5' RACE, and RT-PCR of poly
A mRNA populations isolated fiom 3T3 cells, malignant B ceils and breast cancer cells
and the occurrence of several protein bands of molecular weights predicted by the above
RNA transcripts, as detected in Westem analysis using both monoclonal and polyclond
anti-murine RHAMM antibodies (Entwistle, 1995; Assmann et al., 1998, Hofmann et al.,
1998; Crainie et al., 1999). These results suggest that RHAMM, Iike CD44 is subject to
extensive al temative splicing. The standard form of RHAMM reacts with mtibodies 1, 2
and 3 shown in Fig. III. 1. Shorter RHAMM forms detected by Westem blots react only
with Ab-2 and Ab-3, and therefore appear to represent N-terminal tnincations of the
standard form. These RHAMM forms are maximally expressed early after plating at
subconfluency. These proteins of 60-73 D a have been reported by other laboratories,
nevertheless, they usually represent minor forms of RHAMM protein (Hall et al., 1995;
Masellis-Smith et al., 1996; Nagy et al., 1998; Crainie et al., 1999).
RHAMM Idorms Figo 1.5. RHAMM hfol l t l~ are generated by alternative spliciag of the standard RHAMMs mRNA transcript. Several shorter, activated fonns of RHAMM have also been reported, and these may be generated either by separate M A transcripts, intemai start codon usage of the standard RHAMM ttanscript, or proteolysis of the standard RHAMM protein.
Harrison a d T d e y et al., 1999
1. 2. 7. Domains of RaAMM Related to Ceii Motility and Cell Cycle
Control
Surface FZHAMM regulates signals generated by both HA (Turley et al., 1982;
1994; Mohaptra et al., 1996; Delpech et al., 1997) and growth factors such as PDGF
(Zhang et al., 1998) and TGF-p (Samuel et al., 1993). Structural and hinctional analysis
of RHAMM indicates this protein is largely coiled coil a-helices separated by linear
stretches often preceding functional domains (Fig. 1. 6.). The coiled coil structure may
permit self-association, which would provide a rationale for the effectiveness of mutant
RHAMM f o m s to act as dominant negative hinction suppressors (Hall et al., 1995).
Experiments using exon-specific antibodies suggest that D2-D5 domains are each
required for RHAMM-promoted ce11 motility and for passage through the ce11 cycle (Hall
et al., 1994; Mohapatra et al., 19%; Piang et al., 1998). Deletion or mutation of any one
of these domains is sufficient to ablate the ability of RHAMM to signal aad the ability of
RHAMM overexpression to transfomi fibroblasts (Entwistle et al., 1996). In murine
ceIIs D 1 negatively regulates the ability of shorter RHAMM forrns to activate erk kinase
(Zhang et al., 1998). RHAMM thus resembles oncogenes such as raf, which can be
activated by removal of peptide sequences.
The N-terminal Dl domain unique to R H A M M s that negatively regulates the
function of downstream RHAMM sequences is an entirely novel sequence, and the
manner in which it regulates the function of D2-D5 is not yet clear (Zhang et al., 1999). It
is charactenzed by the presence of an SH3 domain and multiple erkl phosphorylation
sites. It is possible that Dl may cover at least one of RHAMM's downstream domains by
binding to an accessory, regulatory protein. Alternatively, the SH3 binding domain rnay
place RHAMMs in a separate subceilutar cornpartment from RHAMM(A1-5), restricting
access of erk 1, for instance, the key substrates that are required for signaling motiiity and
ce11 cycle progression. D2 encodes an imperfèct leucine zipper, and has been shown to
permit binding of ce11 surface RHAMM to fibronectin in the extracellular matrix, an
interaction that is required for the formation of podosomes, enhancement of celi motility,
and release of metalloproteinases (Cheung et al., 1999). D3 of intracellular RHAMM
mediates an association between RHAMM and MEK 1, forrning a RHAMM/MEK l/erkl
cornplex detected following imrnunoprecipitation of RHAMM (Zhang et al., 1998). This
interaction is indirect since MEK does not bind to RHAMM in vitro. hterestingly, D3
encodes a 7 amino acid sequence, VSLEKEL, that is present in another MEKl binding
protein, MP-1 (Zhang et al., 1999). D4 is a 21 amino acid sequence repeated up to 8
times in murine RHAMM, and is required for full binding of erkl to RHAMM.
Antibodies to this domain added to the culture medium promote ce11 motility and focal
contact turnover, mimicking the effect of hyaluronan and indicating that this domain is
also important to the function of ce11 surface RHAMM.
The first reported functional domains of RHAMM were its hyaluronan binding
motifs present in D5, which encode sequences of basic amino acids that are also cornmon
to other intracellular h y a l a d h e ~ s , such as cdc37 and p68 (Entwistle et al., 1996). The
abiiity of HA to signal motilïty via RHAMM irnplies that the HA binding domains are
also necessary for signal transduction (Hall et al., 1994, 1995). On intraceliular RHAMM
forms, D5 mediates binding of erkl to RHAMM. It therefore appears that cell surface
E2KAMM binds to hyaluronan via the D5 domain, while intracellular forms of RHAMM
utilize this site to bind to erkl. This is consistent with evidence that mutations in this
domain in intracellular RHAMM fonns block activation of erkl (Hail et al., 1995).
Sugar transport signatures are present in the N-terminus of v5 and in the carboxy-
terminal sequence common to ail RKAMM foms, and may be required for transport of
hyaluronan into the ceII (Collis et al., 1998). Furthemore, a cyclin signature present in al1
f o m s is consistent with the involvement of RHAMM in the ce11 cycle (Mohapatra et al.,
1996). However, the protein partnea and the precise molecular function of these
intriguing homologies are not yet clear. Finally, RHAMM contains many potential sites
for post-translational modifications, including N-glycosylation sites, myristoylation sites,
and notably, multiple serine-threonine phosphorylation sites. The effects that these
modifications might have on subcellular localization and protein interactions remain to be
determined.
Fig. 1.6. RBAMM'sPredictedSecondary Structure
Dl- is a novel protein domain that negatively regulates the ability of RHAMM sequence to promote activation of erkl kinase. D2- encodes an imperfect leucine zipper that is required for RHAMM- mediate ce11 rnotility and pcdosame formation- D3-is a novel sequence that is requîred for interaction of intraceiiular RHAMM with MEKl, De- is a novel sequence that is repeated up to 8 times in the murine protein and contributes to the binding of erkl to intracellular RHAMM. DS-encodes hyaiuronan binding motifs that are responsibte for interaction of hyaluronan with ce11 surface RHAMM and erkl binding to intracellular RHAMM.
Hamson and Turley et ai.; 1999
1.3. Tumor Progression is Associated with Elevated Expression of CD44
and RHAMM
In 1989, Stamenkovic and colleagues (Stamenkovic et al., 1989) found that a
variety of carcinoma ce11 lines and solid tumors overexpressed the CD44 gene. In 1991,
Gunthert and colleagues (Gunthert et al., 1991) discovered that an isoform of CD44,
when inserted into the genetic sequence of a non-metastasizing tumor, gave it metastatic
properties. These initial discoveries indicating that CD44 was involved in the metastatic
process led to the large amount of research into the possible mechanisms and the degree
of involvernent of CD44 Today's literatwe indicates that most human cancers with
metastatic properties tend to express increased Ievels of CD44 (Hart et al., 1991; Sy et
al., 1991; Sneath et al., 1998; HemraGayol and Jothy, 1999). In hematopoietic
malignancies, the levels of CD44 expression correlate with tumor dissemination into
lymph nodes (Roos et al., 1991). High levels of CD44 expression have been also noted in
solid tumors such as melanoma (Hart et al., 199 1; Thomas et ai., 1993; Guo et al., 1994),
gastric carcinoma (Washington et al., 1994; Gunthert et ai.. 1995), colon carcinoma
(Heldin and Pertoft, 1993), rend carcinoma (Gunthert et al., 1995) and non-Hodgkin's
lymphoma (Staurder et al., 1995)- Depending on the cell type and perhaps also on the
local microenvironment of the ce11 undergoing malignant transformation, dif5erent
CD44v expression has been correlated with more advanced tumor stage and possibly with
poor prognosis of many but not d l Nmor types. For example, in the case of non-
Hodgkin's lymphomas (Stawder et al., 1995) and colon carcinoma (Mulder et al, 1997),
expression of CD44v6 is correlated with poor prognosis, whereas CD44v4-v10 is
sufficient to promote metastatic behavior in pancreatic carcinoma ceils (Sleeman et al.,
1997). However, contradictory data is found regarding the correlation between CD44
expression and cancer progression in breast carcinoma
Like CD44 RHAMM expression is variable depending on ce11 type. While
RHAMM expression is absent or at low levels in non-transformed confluent cells in vitro
and in normal most fully-differentiated tissues in vivo (Turley et ai., 1989; Pilarski et al.,
1994, 1999; Zhang et al., 1998; Cheng et al., 1999), it is markedly up-regulated in
fibroblasts following TGF-8 stimulation (Samuel et al.. 1993) and expression of the ras
oncogene (Turfey et al., 1991; Hardwick et al., 1992; Turley et al., 1993; Hall et al.,
1995). Enhanced expression of RHAMM is observed in diseased cells such as fibroblasts
following injury (Savani et al., 19951, 199%; Paiwand et al., 1999), in smdl ce11 lung
carcinoma (SCK) celis, in adenocarcinornas, squamous ce11 carcinomas, and large cell
carcinomas (Teder et al., 1995). RHAMM overexpression has also been linked to late
stage astrocytoma (J. Rutka, personal communication), and to poor prognosis in lung
adenocarcinorna associated with the presence of mutant active ras (M-S. Tsao, personal
communication). Moreover, RHAMM expression in breast cancer is linked to outcome
associated with lymph node metastasis capabilities and is an independent prognostic
factor for poor outcome (Wang et al., 1998). Finaliy, RHAMM has been reported to be
overexpressed in malignant versus benign human pancreatic tumor cells (Abetamann et
al., 1996). In al1 these studies, high levels of RHAMM mRNA expression correlated
with the aggressiveness of tumor cells, poorly differentiated phenotype, and a high
metastatic potential when injected into nude rnice (Abetamann et al., 1996; Wang et al.,
1998; Pilarski et al., 1994, 1999).
1.4. Hypothesis, Rationale, and Objectives of this Study
Several reports suggest that expression of both CD44 (Jamal et al., 1994; Penno et
al., 1994; Kogerman et al.' 1996) and RHAMM (Hall et al., 1995; Wang et al., 1998)
appear to be regulated by mutant active ras overexpression. The ras oncogene and the
activation of the raderk signaling pathway have been implicated in breast cancer
development (El-Ashry and Lippman, 1994). Molecular mechanisms responsible for
increased activation or expression of MAP kinase in breast cancer in the absence of
mutant ras forms have not ken clearly defined, although dues may be provided by
observations that both CD44 (Jamal et al., 1994; Penno et al., 1994; Kogerman et al.,
1996) and RHAMM are associated with erk activation and activity of genes regulated by
erk (Bourguignon et al., 1997; Wang et al., 1998, Yu and Stamenkovic, 1999).
Furthemore, both CD44 and RHAMM have k e n linked to formation of invadopodia
(Bourguignon et al., 1998a; B. Yang, personal communication), consistent with a role in
tumor metas tasis and progression.
In this thesis, it is hypothesized that RHAMM and CD44 expression, and erk
activation are linked in the motility of several human breast cancer cell lines that Vary in
their aggressiveness in nude mice.
Therefore, this project was designed to fuKiJl the foilowing objectives:
A) To determine if levels of RHAMM, CD44 and active erk are higher in the more
motile and aggressive ce11 lines.
B) To assess if the expression of mutant active ras, erk, CD44 and RHAMM are
correlated.
C) To test the biologicd effects of blocking erk activity in these aggressive ceU lines.
D) To investigate if RHAMM and erk, as well as RHAMM and CD44 CO-distribute and
CO-associate on more aggressive ce11 lines.
E) To further understand the signaling events downstrearn of the ras pathway which
involves RHAMM and CD44
CHAPTER II
MATERIALS AND METHODS
II. 1. Ceil Culture
Human breast carcinoma ce11 lines MDA-MB-23 1 and MCF-7 were obtained
from American Type Culture Collection (Manassas, VA) and were cultured in
Dulbecco's Modified Eagle's Medium (DMEM) (Gibco BRL, Burlington. Ootano)
supplemented with 10% (v/v) heat-inactivated fetal bovine serurn (FBS) (Hyclone
Laboratories Inc., Logan, UT) and IO mM HEPES (Sigma Chernical Co., St. Louis, MO),
at pH 7.2.
Immortalized normal human breast epitheliai ce11 lînes MCF-lOA transfected with
the empty pH106 plasmid containing the neomycin cesistance gene, MCF-1OA ceïïs
transfected with human H-ras protooncogene, or with human mutant H-ras oncogene
mutated at (G12-V12). were a kind gift of Dr. Channing Der (North Carolina) and grown
as described by Soule et al. (1990), and Basolo et al. (1991). Bnefly, the ceils were
grown in DMEMIF-12 (1:l) supplemented with 5% equine serum, 0.1 @mi cholera
toxin, 10 pg/d insulin (Gibco BRL), 0.5 p g h l hydrocortisone (Sigma) and 0.02 pg/ml
epidermal growth factor (Coilaborative Research Inc., Pdo Alto, CA).
Al1 ce11 lines were routinely maintained on plastic tissue culture plates (Costar,
Cambridge, MA) at 37OC in a 95% air, 5% CO2 atmosphere in a 98% humidity-
controlled incubator. MDA-MB-23 1 and MCF- 1 OA-mutant active ras cells were
passaged every 2-3 days while MCF-7, MCF- 1OA-empty vector, and MCF- 1OA-
protooncogene ras cell lines were passaged every 4-5 days prior to their reaching
confluency. To subculture, ce11 were washed with phosphate-buffered saline (PBS) then
detached with a non-enzymeceil-dissmiation solution (Dissociation Medium, Sigma).
Al1 experiments were conducted with 50% subconfluent cells and analysis done at 2-24
hours as indicated foilowing subculturing in growth medium.
II. 2. Antibodies
Polyclonal RHAMM antibodies (Zymed, San Diego, CA) used in this study were
prepared against the foilow ing sequences: antibody - 1 was prepared against peptide
sequence KSKFSENGNQKN (aa150-162) of human RHAMM (Wang et al., 1996;
Assmann et al., 1998), antibody-2 was prepared against VSIEKEKlDEKS (aa. 217-229)
of human RHAMM; and antibody-3 was prepared against the peptide sequence
QLRQQDEDFR corresponding to a.& 543-553 of human RHAMM. These peptides were
chosen for antibody preparation based on favorable surface probability, hydrophilicity,
and antigenic index, using protein analysis software Antheprot 2.9g. Candidates were
then analyzed using Prosite software for potential pst-secondary modification sites that
may interfere with antibody recognition of native proteins and based upon these analysis,
the optimal sequences indicated above were selected, Antibodies were prepared in three
month old New Zealand white rabbits. To determine antibody specificity, anti-RHAMM
antibody-2 pre-incubated with lûû-fold excess glutathione-S-transferase (GST)-RHAMM
fusion protein linked to beads (1 pg antibdy-2/20 pi of beads) was incubated for 1 hr at
4 OC on a rotator, then centrihged for 5 minutes. The resulting supernatant was used to
probe the membranes. Non-immune rabbit IgG was used as control.
Monoclonai antibodies to p2 1 ras and the MAP kinase (erk 1) were purchased from
Oncogene Science (Cambridge, MA) and an anti-CD44 antibody (Hemes3) was the kind
gift of Dr. Sirpa Jaikanen (University of Kuopio, Finiand).
For immunoblottiag detection, horseradish peroxidase (HRP)-conjugated goat
anti-mouse IH+L) IgG was purchased from Bio-Rad Laboratones (Hercules, CA), and
donkey HRP-conjugated anti-rabbit IgG specific to F(abT)2 fragment was purchased from
Amersham Canada (Oakviiie, Ontario). Al1 other fluorochrcme-conjugated secondary
antibodies were specific to the F(ab7)* fragment of primary antibodies and were obtained
form Jackson ImmunoResearch Laboratones (West Grove, PA).
II. 3. Western Immunoblotting and Imrnunoprecipitation
Cells were plated at 50% subconfluence for 12 hours, after celi plating, were
washed with ice-cold PBS, lysed with ice-cold RIPA lysis buffer (25 rnM Tris-HCl, pH
7.2, 0.1 % SDS, 1 % Triton-X-100, 1 % sodium deoxycholate, 0.15 M NaCl, 1 nM EDTA,
and 50 mM HEPES [pH 7-31) containing the protease inhibitors leupeptin (1 pg/ml),
phenylmethylsulfonyl fluoride PMSF, 2 mM), pepstatin A (1 glrnl), aprotinin (0.2
TlU/rnl) and 3,4-dicholoroisocoumarin (200 mM), sodium orthovanadate, and 1 mM NaF
(1 rnM) (Sigma). Ce11 lysates were then micro-centrifuged at 13,000 g for 20 minutes at
4OC (Heraeus Biofuge 13, Baxter Diagnostics, Mississauga, Ontario) after standing for 20
minutes on ice. Protein concentrations of the supematants were determineci using the DC
protein assay (Bio-Rad). 10 pg of total protein from each ce11 lysate was loaded and
separated by electrophoresis on a 10% SDS-PAGE gel together with prestained
molecular weight standards (Gibco BRL). Following electrophoresis, and transfer to
nitrocellulose membranes (Bio-Rad) in a buffer containing 25 mM Tris-HCl (pH 8.3),
192 mM glycine, and 20% methanol using electrophoretic transfer cells (Bio-Rad) at
lOOV for 1.5 hours at 4OC. Additionai protein binding sites on the membrane were
blocked with 5% defatted milk in TBST (10 mM Tris base (pH 7-4). 150 m M NaCl, and
0.1 % Tween 20) (Sigma). The membranes were then incubateci with the primary antibody
for either RHAMM (antibody-1 or -2), ras, erk or CD44 (ali diluted at 1: 1 0 or 1 pghl
in 1 % defatted milk in TBST) for 2 hours at room temperature and washed three times at
15 minute intervals with 1% defatted miik in TBST. Immunodetection was performed
using secondary antibodies conjugated to HRP (diluted 1:Sûûû (1 pg/mi) in 1% defatted
milk in TBST for 1 hour at room temperature followed by three washes with TBST.
Blotting was visualized by the enhanced chemiluminescence (ECL) Western blotting
detection system (Arnersham Phannacia Biotech, Piscataway, NI) according to the
manufacturer's instructions. Quantification of optical densities of the reactive protein
bands was performed on a Bio-Rad Video Densitometer. The specificity of the anti-
RHAMM antibody was confirmed by probing blots with either non-immune rabbit IgG,
or anti-RHAMM antibody-2 pre-incu bated with RHAMM fusion protein as stated above.
To account for variations in loading, pad le l SDS gels were carried out with the
experiments and equd amounts of the protein were separated on these gels. These other
gels were then stained with Coomassie blue dye in order to confirm equal loaciing. The
densitometric results were presented as mean of three experiments + standard deviations.
Immunoprecipitation analyses were performed using 400 pg of protein from each
ce11 lysate mixed with 5 pg of either anti-RHAMM antibody-2, anti-CD44, antierkl,
anti-rabbi t IgG (for polycIona1 an tibodies j , or anti-mouse IgG antibodies (for monoclonal
antibodies). After 12 hours of incubation at 4°C on a rotator, 25 pl of a 50% suspension
of protein MG-Sepharose beads (Gibco BRL) was added to each tube and the samples
were mixed end-over-end for another 4 hours at 4 OC. The beads were pelleted by brief
centrifugation at 7000 g and washed three times with cold 0.5% Triton-X-100/PBS.
Bound proteins were released from the beads by boiling in 25 @ of 2X L a e d i buffer
for 5 minutes. Protein samples were subjected to 12% SDS-PAGE and imrnunoblotted in
Western assay as described above.
II. 4. Time-Lapse Cinemicmgraphy
To quanti@ the effect of blocking CD44 (Herrera-Gay01 and Jothy, 1999) and
RHAMM (Hall et al., 1995; Pilarski et al., 1999) antibodies, cell lines expressing
different levels of RHAMM were seeded on T-25 flasks (Costar, Cambridge, MA) at 1 6
cells. Cells were incubated with either anti-RHAMM antibody (Antibody-2, 30 pghl),
anti-CD44 antibody (Hemes3,30 pg/ml), or mixture of anti-RHAMM (Antibody-2,30
pg/rnl) and anti-CD44 antibodies (Hermes3, 30 pg/rnl) for 30 min prior to filming. As a
control, a mixture of mouse and rabbit IgG (30 pg/ml each) was used. Cell locomotion
was monitored for a period of 6 hours using a X10 modulation objective (Zeiss,
Germany) attached to a Zeiss Axiovert LOO inverted microscope equipped with Hoffman
Modulation contrat optical filters (Greenvale, NY) and a 37 OC heated stage. Ce11 images
were captured with a CCD video camera module attached to a Hamamatsu CCD camera
controller. Motility was assessed using Northem Exposure 2.9 image anaiysis software
(Empix Imaging, Mississauga, Ontario). Nuclear displacement of 20-30 cells were
measured and data were subjected to statistical analysis (see below). Each expriment
was repeated at least three times. To test the involvement of the MAP kinase pathway in
the motility of these cells, PD098059 (2-[2'-amioo-3'-methoxyphenyl]-oxanaphthalen4
one]) compound, which inhibits MEKl (Dario et al., 1995), was purchased from
Calbiochem Biosciences (Mississauga, Ontario). A stock concentration (50 mM) of this
compound was prepared in DMSO and frozen at -70 OC. The cells were incubated with
the MEK inhibitor at 50 p M in complete culture medium 30 minutes before the
beginning of motility filming. DMSO alone was used as a control. The results of motility
analyses were expressed as means ( W o u r ) means + standard deviations, unless
otherwise indicated. Statisticaily significant (@.OS) differences between means were
assessed by the unpaireci Student's t-test method, performed using Micosoft Excel '97
software.
II. 5. Flow Cytometry (FACS)
Cells were grown to 50% subconfluence on 100 mm culture plates in growth
media, 12 hours after subculturing, and rinsed in cazc-free Hank's Buffered Saline
Solution (HBSS)/20 mM HEPES, pH 7.3. Cells were harvested with non-enzymatic
HBS S-based ce11 dissociation solution (S igrna) and suspended in cold
1 O%FCS/HBS S/HEPES (FACS buffer). The viability of released cells was establis hed to
be between 85% and 95%, by Tsrpan blue exclusion. An aliquot of 2 x 1o6 cells was
incubated with primary antibodies-1, -2 or -3 (1: 100, 1 pg/pl) in a total volume of 200 pl
of FACS buffer for 30 minutes on ice, and washed three times in cold FACS buffer.
Rabbit IgG was used as a negative control for each ce11 line. Fluorescein isothiocyanate
(FiTc)-conjugated goat anti-rabbit IgG (1:300 dilution, Sigma) in FACS buffer was then
added and incubated for 30 minutes in the dark on ice- The cells were washed again and
exarnined with a flow cytometer supplied by the Hospital for Sick children, Toronto,
using FACS Calibur with Cell Quest acquisition and analysis software (Becton
Dickinson, Lincoln Park. No. Viable ceiis were gated based on forward and side scatter
to eliminate dead aggregates and debris, and then the distribution of fluorescence
intensity was cdculated. Rabbit IgG was used as control ate 1: 100 of 1 pl /ml dilution.
II. 6. Immunofluoreseence Staining
Cells were plated at 50% confluence on sterile g las coverslips in 35 mm tissue
culture plates for 12 heurs, Culture medium was then aspirateci, and attached cell
monolayers were rinsed in PBS then fixed in a solution of 2 to 4%
paraformaldehyde/PBS for 10 minutes. Cells were then washed three times for 5 minutes
each in IxPBS, then non-specificity binding sites were blocked with 3% BSNPBS for I
hour at room temperature. Monolayers were washed three times with PBS, then were
incubated with a 1: 100 dilution of anti-RHAMM (Ab-2) (1 pg/pi), antierk (1 pg/pi),
anti-CD44 (1 pg/pl), and anti-ras (1 pglpl) antibodies in 1% BSA for 1 hour at room
temperature. The cells were washed and incubated with 1:300 dilution of secondary
antibody in 1% BSA labeled with FITC or TRïTC (trisrhodamine isothyiocyanate).
Following another three washes, the cover slips containing the cells were mounted ont0
glas slides and examined using a Leica TCS 4D laser scanning confocal microscope
equipped with Scanware 5.0 software.
CHAPTER III
RESU LTS
III. 1. AntibocUes SpeciBcaiïy Detect RHAMM
In Western blot anaiysis, antibodies-2 and -3 were used to probe 5 pg of murine
RHAMM(A1-5 : exons one to five deleted) recombinant protein (without GST), prepareâ
from a mouse RHAMM cDNA (Entwistle et al., 1995; Hohann et al., 1998). These
antibodies were prepared against sequences that are entirely conserved between mouse
and hurnan RHAMM. GST done was prepared as a control. Antibodies recognized the
73 kDâ -(Al-5) as weU as a 53 kDa proteolytic fragment of murine RHAMM
recombinant protein (Fig. III. 1A. and B.). Antibodies did not detect GST alone (Fig.
III. 1C.). Non-immune cabbit IgG also did not detect recombinant RHAMM protein and
was used as negative control (Fig. m. 1B.).
III. 2. Cell Surface RHAMM Expression Varies with T h e on the
Surface of Human Breast Cancer Cells
Two human breast cancer ce11 lines, MDA-MB-231 and MCF-7 which differ in
their tumorigenicity and aggressiveness (Thompson et al., 1992; Bae et al., 1993;
Sommer et al., 1994) were andyzed for ce11 surface RHAhfM. MDA-MB-23 1 ceils,
derived from an estrogen receptor-negative, vimentin-positive human breast
adenocarcinornas are invasive and metastatic in nude rnice (Thompson et al., 1992).
These cells have been reported to produce high levels of hyaluronan (Heldin et al., 1996)
and to expresses high levels of CD44 (Culty et al., 1994; Ponta et al., 1995). Ce11 surface
RHAMM was detected using FACS analysis at 2, 12-17 and 24 hours following celi
plating (Fig. III. 2A-D.). Using anti-RHAMM antibodies-1, -2 and -3, MDA-MB-23 1
cells severally express 2-3 fold higher levels of ce11 surface RHAMM than the MCF-7
cells, but the exact arnount and ciifferences in expression Vary with time after plating
when cells are maintaineci at 50% subconfluence. (Fig. III. 2A-Do). In terms of
differential expression, at 2 hours after cells plating, ce11 surface RHAMM was 2-fold
higher on MDA-MB-231 cells than on MCF-7 celis (Fig. III, 2A.) and this increased to
Cfold higher at 12 hours after ce11 plating (Fig. III. 2B.) but dropped to 2-fold higher
than MCF-7 cens at 17 (Fig. III. 2C.) and 24 (Fig. III. 2D.) hours. In absolute times,
using a semilog scale, ceil surface RHAMM expression for both cell Lines was high at 2
hours, low at 12 hours and high again at 17 and 24 hours after cell plating (Fig. III. 2E.).
The presence of two FACS peaks for MDA-MB-231 cells suggests that at 12 hours after
piating most cells expressed very low levels of RHAMM but a subset of cells expressed
high levels of this protein (Fig. III. 2B.).
III. 3. Breast Cancer C e h Express Several RHAMM Isoforms
Western blot analyses were conducted using anti-RHAMM antibodies as shown
in Fig. m. 1. Using Ab-2, three RHAMM proteins were detected in MDA-MB-231 and
MCF-7 cells; 85 kDa, 63 kDa and 43 kDa proteins were detected. Ab-1 detected one
RHAMM protein of 85 kDa in both the MDA-MB-23 1 and MCF-7 cells. The specificity
of antibody-2 was confirmed by cornpetition with murine recombinant RHAMM(A1-S),
which blocks Ab-2 detected proteins (Fig. III. 3C.). MDA-MB-23 1 cells expressed 3.8-
fold higher levels of the 85 kDa protein and 3.5-fold higher levels of the 63 kDa protein
than MCF-7 cells but the sarne amount of the 43 kDa protein was expressed in both ce11
lines, as shown by densitometric analysis (Fig. III. 3.).
III. 4. RHAMM Overexprrssion is Associated with the PFesence of
Mutant Active ras
RHAMM expression has previousiy been associated with the presence of mutant
active H-ras in murine fibroblasts (Turley et al., 1993; Haii et al., 1995). with H-ras over-
expression in primary breast mmor biopsies (Wang et al., 1998) and with activation and
expression of erk kinase (Zhang et al., 1998). We therefore examined the effect of
transfecting the proto-oncogene ras or mutant active ras in immortalized hmnan bfeast
epithelial cells on RHAMM expression (Soule et al., 1992). Antibody- 1 detected an 85
kDa RHAMM protein in MCF-1OA cells transfected with empty vector (Fig. m. 4A.),
whereas Ab-2 detected 43 kDa and 63 kDa proteins in these cells (Fig. III. 4B.). The
overexpression of either ras protooncogene or mutant active ras was associated with
increased expression of the 85 and 63 kDa proteins (Fig. III. 4A. and B.) and a down-
regdation of 43 kDa (Fig. m. 4B.). The overexpression of ras in these cells was
confirmed by Western immunoblotting (Fig. III. 5.). The specificity of the RHAMM Ab-
2 was confirmed by its ability to recognize the murine RHAMM-GST fusion protein (Al-
5) on Westem blots (Fig. II. 1A. and B.) and by its ability to be blocked by excess
murine RHAMM-GST fusion protein (Al-5) (Fig. m. K.). A 120 kDa non-specific
protein was not blocked by excess fusion protein. These results were quantified using
densitometry (Fig. III. 4D.).
IIL 5. REIAMM Overexpression in MDA-MB-231, MCF-7, or MCF-
10A Ceiis Correlates with the Overexpression of ras, Presence of Active
erk, and with High Leveis of CD44
Western and densitometric anaiysis showed a 3-fold and 2.7-fold enhanced level
of ras protein and active erkl protein, respectively in MDA-MB-231 ce11 compared to
MCF-7 ce11 lines (Fig. III. S.). This is consistent with the presence of ras mutation in
MDA-MB-231 cells (Gilhooly and Rose, 1999) and the absence of mutation of ras in
MCF-7 cells (Bos, 1988). Interestingly active erk2 protein expression was the same in
the two ce11 lines (Fig. III. 5.). Since it has been reported that the HA receptor CD44
plays a role in the aggressive phenotype of MDA-MB-231 ce11 line (Culty et al., 1994),
CD44 expression was determined. Expression of CD44s, corresponding to the 85 kDa
isoform, was 8-fold higher in MDA-MB-231 cells than in MCF-7 cells, as quantified by
densitornetry (Fig. III. 5.).
MCF- IOA celis transfected with mutant active ras exhibited a six-fold induction
in the expression of CD44s corresponding to the 85 kDa isoform (Fig. III. 6.).
Furthemore, a three-fold increase in the levels of active erkl and erk2 expression was
correlated with ras-transfection, confiming the downstream position of erk in the ras-
MAP kinase pathway (Fig. m. 6.).
III. 6. REAMM Co-distributes with erk and CD44 in Breast Cancer
Cells
MDA-MB-231 cells exhibited intense staining for RHAMM in the nuciei and
perinuclear regions and diffuse staining in ce11 ruffies (Fig. III. 7A.), whereas weak
RHAMM staining was seen in the perinuclear regions of MCF-7 cells w~g. IIL 7B.).
Erk CO-distributed with RHAMM in the nuclei and perinuclear regions of MDA-MB-231
cells (Fig. III. 7A.). Treatment of MDA-MB-23 i with the PD098059, a MEK inhibitor,
led to the impairment of nuclear colocalization of RHAMM and erk (Fig. III. 7C.)
compared to DMSO-treated cells which were used as a negative control @ig. m. 7D.). CD44 expression was concentrated on the membrane and in the perinuclear regions of
MDA-MB-23 1 cells. RHAMM and CD44 CO-distributed in non-penneabilized celis at
the tips of ce11 processes and to a smaii extent in the perinuclear regions (Fig. III. 7E.).
Permeabilizing cells with 0.1 % Triton-X following fixation enhanceci visuaiization of the
perinuclear CO-localization of intracellular RHAMM and CD44 in MDA-MB-23 1 cells,
but abolished staining for RHAMM in the cell processes (Fig. III. 7F.). Furthemore,
staining for CD44 or RHAMM observed in MCF-7 cells was weak in either non-
permeabilized (Fig. III. 76.) or permeabilized cells (Fig. III. 78.). Rabbit and mouse
IgG were used as negative controis (Fig. III. 7L).
Intense staining and CO-localization of RHAMM and erk was observed in the nuclei
and ruffles of MCF-1OA ceils transfected with mutant active ras (Fig. III. SA.),
compared to the weak staining and absence of CO-Iocalization in either cells over-
expressing the ras proto-oncogene or cells transfeçted with empty vector alone (Fig. III.
8B.). Very faint staining of RHAMM and erk was present in the cells transfected with
empty vector (Fig. III. SC.). MCF-IOA mutant active ras-transfected cells were then
treated with PDû98059 (Fig. III. %D.), which debilitated the CO-localization of RHAMM
and erk in the nuclei of these cells as compared to the DMSO-treated ceils (Fig. III. SE.)
used as control. IgG was used as a negative control (Fig. III. 8F.).
In these ceUs and in contrast to MDA-MB-231 cells, RHAMM and CD44 co-
Iocalized at the points of ceIl-to-celi contact (Fig. III. SR). Permeabilizatioa of ceils
revealed a CO-localization of CD44 and RHAMM in the p e ~ u c l e a r regions of these celis
(Fig. III. 86). Cells that were transfected with normal &ras (Fi~gs. III. 8H. ami 1.) or
transfected with empty vector (Figs. III. SJ. and K.) did not show a CO-locaiization of
RHAMM and CD14. IgG was used as negaiive control (Fig. III. SL.).
Furthemore, CD44 was found to be in close proximity to ras when co-
irnrnunostaining of ras and CD44 was performed (Fig. III. 9.). In MDA-MB-23 l (Fig.
III. 9A.) and MCF-IOA-NeoT2 (Fig. III. 9B.) cells, c-H-ras CO-localized with CD44
close to the cell membrane compared to no CO-localization seen in MCF-7 (Flg. III. 9C.)
and MCF-LOA-Neo cells (Fig. m. 9D.). IgG was used as negative control (Fig. III.
9E.).
III. 7. RaAMM Co-bnunoprecipitates with erk and CD44 in MDA-
MB-231, MCF-7, and in ras-transfected Breast Epithelial Cells
The ability of RHAMM antibodies to CO-immunoprecipitate components of the
MAP kinase cascade was assessed (Fig. III. 9.). Erkl CO-immunoprecipitated with anti-
RHAMM antibody-2 in both the MDA-MB-231 and MCF-IOA cells transfected with
mutant active ras, whereas lower amounts of erk were CO-immunoprecipitated with
RHAMM in MCF-7 cells and in MCF- IOA-Neo cells, respectively (Fig. III. 9A.). Erk-2
CO-immunoprecipitated with RHAMNI only in the MDA-MB-23 1 cells w~g. m. 9A.). A
63 kDa RHAMM was CO-immunoprecipitated with an antierk antibody. Only MDA-
MB-23 1 cells and MCFIOA-NeoT2 ceils showed intense staining of RHAMM foilowing
imrnunoprecipitation by erk antibody (Fig. III. 9A.).
RHAMM also CO-imrnunoprecipitated with CD44. Two isoforms of CD44 (86
kDa and 1 16 kDa) were CO-immunoprecipitated with anti-RHAMM antibody-2 in MDA-
MB-23 1 cells and in MCF-IOA cells transfected with mutant active ras (Fig* III. 9B. and
Cm). However, CO-imrnunoprecipitation was not observed in MCF-7 or MCF-1OA ceils
transfected with vector only. To m e r c o n f i i this CO-association, an anti-CD44
antibody was used to co-immunoprecipitated RHAMM and this antibody co-
immunoprecipitated an 85 kDa and a 63 kDa RHAMM isoforms in both M'DA-MB-23 l
and MCF-7 cells mg. m. 9D.). The same anti-CD44 antibody CO-imrnunoprecipitated
RHAMM in MCF-1OA cells. In ras-transformed breast epithelial cells (MCF-1OA-
NeoT2), both 85 kDa and 63 kDa RHAMM isoforms were detected, but only the 85 kDa
isoform was detected in cells transfected with an empty. In al1 experiments, rabbit IgG
and mouse IgG were used as negative controls for mock imrnunoprecipitation (Fig. III.
9A-Dm).
III. 8. RHAMM and CD44 are Required for the Locomotion of MDA-
MB-231 Cells and Ce& Transfected with Mutant Active ras
The locomotion of MDA-MB-231 cells was significantly higher than the
locomotion of MCF-7 cells; 60.2 IG.27 Cun/hour versus 13.39H.84 Crm/tiour (p<0.00 1).
Anti-RHAMM antibody-2 significantly inhibited the locomotion of MDA-MB-23 1 cells
(pc0.005) (Fig. III. 10A.) but had only minor effects on MCF-7 cells that were not
statistically significant. Anti-CD44 antibody signif~cantly decreased the motility of
MBA-MD-23 1 cells to the same level as anti-RHAMM antibodies (W.03). To assess if
the effects of anti-CD44 and anti-RHAMM antibodies were additive, anti-CD44 and
RHAMM antibodies were mixed and their combined effect on motility of MDA-MB-23 1
cells was assessed. Mixing antibodies did not fbrther inhibit MDA-MB-23 1 ceIl motility
(Fig. III. 10A.).
Because erk has been impiicated in breast cancer cell motïiity (Zeigler et al., 1999;
Xing and Imagawa, 1999), and MDA-MB-23 1 ceiis express high levels of this kinase,
and since RHAMM and CD44 have both been reported to regdate erk kinase activity
(Hofmann et al., 1993; Zhang et al., l998), the effect of inhibiting this kinase on MDA-
M . - 2 3 1 ce11 motility was examined. A MEK inhibitor, PD98059, most strongly blocked
MDA-M.-231 cell motility (pd.001) relative to the effects of antibodies (Fig. III.
10B.).
The three MCF- 1OA-denved ce11 lines also exhibited significantly different rates
of random ce11 motility, with Iocomotion k i n g significantly higher in cells transfected
with mutant active H-ras (37.68k3.87 Crm/hr) (pd.ûû1) (Fig. m. 10C.). Anti-RHAMM
antibodies strongly blocked the locomotion of mutant active ras-transforrned ce11 lines
(2.5 fold, p<O.OOl) (Fig. III. 1W.). The anti-CD44 antibody also decreased the motüity
of mutant active ras-transformed ce11 lines (2-fold, p<0.001). Combining the anti-
RHAMM and a n t i - C M antibodies, however, did not further inhibit ce11 motility relative
to each antibody alone (Fig. m. 10C.). The MEK inhibitor (PDû98059) also significantly
decreased ce11 motility to a level similar to that observed with the anti-RHAMM antibody
(Fig. III. 10D.).
SECTION III. 9
Fig. m. 1.
Confirmation of the specificities of RHAMM antibodies-2 and -3 by immunoblot
analysis. Murine RHAMM(A1-5) recombinant protein (5 mg) was electrophoresed on a
10% SDS gel, transferred to nitrocellulose, and probed with antibodies-2 and -3, which
detected 73 kDa protein bands correlating to RHAMM(A1-5) and 53 kDa proteolysis
product respectively (A and B). GST alone and non-immune rabbit IgG were used as
controls (B and C).
Fig. III. 2.
Detection of RHAMM expression on the surface of MDA-MB-23 1 and MCF-7 cells by
FACS analysis. FACS analysis was performed using anti-RHAMM antibodies-1 and -2
following 2, 12, 17, and 24 houa of subculturing (A-D). Anti-RHAMM antibody-3
replaced antibody-1 at the 12 hour time point (B). Plotting results of the percentage of
gated cells on a log immunofluorescence intensity from mean of two experiments + standard deviations, revealed that ce11 surfice RHAMM was approximately 2-3-fold
higher on MDA-MB-231 cells compared to MCF-7 cells using anti-RHAMM antibodies
specific to different regions of the RHAMM protein (E). CeIl surface RHAMM
expression was most heterogeneous, shown by two single FACS peaks, at 12 hours after
subculturing of both ce11 lines (B). IgG was used as a negative control.
Fig. m. 3.
Western immunoblot analyses of RHAMM expression in MDA-MB-23 1 and MCF-7
cells. Anti-RHAMM antibody- 1, which detects only standard form of RHAMM (A), and
antibody-2, which detects both RHAMMs and isoforms of RHAMM (B), were used in
the anaiyses. Three major RHAMM protein bands of 85 kDa, 63 kDa and 43 kDa, were
detected in these cells. The specificity of the anti-RHAMM antibodies were shown by
cornpetition studies using RHAMM fusion protein preincubated with anti-RHAMM
antibody-2 (C). Densitometry analysis was used to quantify the amounts of the different
RHAMM isofonns expressed in these ce11 iines and the resufts are presented as mean of
three experiments + standard deviations @).
Fig. III. 4.
Western immunoblot analyses of RHAMM expression in ras-transfected MCF-IOA cells.
Antibody-1 detected greater amounts of an 85 kDa RHAMM protein in MCF-1OA cells
transfected with either the ras protooncogene (NeoN) or mutant active ras (Neo-2T) (A).
Antibody-2 detected 85 kDa and 63 kDa, and 43 kDa proteins in similar experiments (B).
As a control, the anti-RHAMM antibody-2 was cornpeted out with excess RHAMM-GST
fusion protein, and was then used to probe the blots (C). The densitometry graph shows
the quantity of RHAMM protein presented as mean of k e experiments + standard
deviations in the three MCF- 1OA ceii lines (ID).
MC F-1 OA-protooncogen r is *< "
MCF-1 OA-vcctor alone
MCF1 OA-protoonwgen ras
MCI;-1OA-mutant active ras
MCF-1 OA-vector a lone
MCF-10A-protoo~~ogen ras
MC F-1 OA-mutant active n u
Fie. III. 5.
Western immunoblot analyses of active erk, H-ras, and CD44 expression in MDA-MB-
23 1 and MCF-7 ceus. Monoclonal antibodies against ras, CD44 and phosphorylated erk
were used for probing the blots. Densitometric andysis presented as mean of three
experiments + standard deviations showed enhanced protein levels of ras, CD44, and
active erkl in MDA-MB-23 1 celis compared to MCF-7 cells.
Fig. III. 6.
Western immunoblot analyses of active erk, H-ras, and CD44 expression in ras-
transfec ted MCF- IOA cells* Monoclonal antibodies against ras, CD44 and
phosphorylated erk were used for probing the blots . In MCF-1OA cells, levels of active
erk, and CD44, expression correlateci with the levels of ras expression, Shown by the
densitometry analysis which is presented as mean of three experiments 2 standard
deviations, active erkl and CD44 levels were highest in celis transfected with mutant
active ras.
E R K - 1- IEI ERK- 2-
Fig. 1 ' . 7.
Confocal microscopie analysis of RHAMM, erk and CD44 expression in MDA-MB-23 1
and MCF-7 cells. Antibody-2 and antierk monoclonal antibodies were used for
RHAMM (green color) and erk (mi color) staining. RHAMM and erk displayed intense
nuclear staining in MDA-MB-231 ceils (A) but diffuse and subtle perinuclear staining in
MCF-7 cells (B). Nuclear CO-distribution of erkl and RHAMM (yeliow color) was
detected only in the MDA-MB-23 lcells (A). When MDA-MB-23 1 ceils were treated
with PD098059, a MEK inhibitor, nuclear CO-locaiization of RHAMM and erk was not
seen (C) compared to DMASO treated cells (D). When ceUs were fixed with 2%
paraformaldehyde, RHAMM (green color) and CD44 (detected by Herrnes 3; red color )
were CO-distributed on the vesicles close to the ce11 membrane and ceil processes of
MDA-MB-23 1 cells (E). Upon treatment of celis with 4 8 paraformaldehyde and 0.1 %
Triton-X, intracellular RHAMM and CD44 CO-locaiization was observed in the
perinuclear regions of MDA-MB-23 1 cells O. However, CD44 or RHAMM staining in
MCF-7 celIs was week in either non-permeabilized (G) or permeabilized cells (8).
Rabbit and mouse IgG were used as negative controls (1). The line bar indicates 25 mm;
the arrows point to CO-localization of RHAMM either with CD44 or erk.
Fig. HI, 8.
Confocal microscopie andysis of RHAMM, erk and CD44 expression in ras-transfected
MCF- 1OA cells. Immunofluorescence staining using both antibody-2 against RHAMM
(green color) and anti-erk antibody ( r d color), showed intense nuclear staining of MCF-
10A-NeoT2 cells (A), compared to less intense, perinuclear staining of MCF- IOA-NeoN
cells (B) and to the faint staining of MCF-1OA-Neo ceUs (C). The nuclear CO-distribution
of RHAMM and erk was not seen in the MCF-1OA cells transfected with mutant active
ras following treatrnent of the cells with MEK inhibitor, PDû98059, @) compared to
DMSO treated cells (E). IgG was used as a control(F). The CO-distribution of CD44 and
RHAMM (yellow color) was seen at points of cell-to-cell contact when MCF-1OA-
NeoT2 ceUs were fmed with 2% paraformddehyde (G), but was present in the
perinuclear regions of cells treated with 4% parafomaldehyde and O. 1% Triton-X (H).
The latter staining pattern was not observed in MCF-1OA-transfected with normal ras 0
and .J) or in MCF- 1OA-transfected with empty vector (K and L), used as controls, which
were sirnilarly treated with 2% parafomaldehyde (I and K) or 4% paraformaldehyde and
0.1% Triton-X (J and L). The line bar indicates 25 mm; the arrows point to co-
localization of RHAMM either with CD44 or erk.
Fig. m. 9.
Confocal rnicroscopic analysis of CD44 and ras expression in breast cancer ce11 lines and
in ras-transfected breast epithelial cells. Antibodies specific to CD44 (red color) and ras
(green color) were used. CD44 CO-localization (yellow color) was present with ras in
MDA-MB-23 1 (A) and MCF-1OA-NeoT2 celis (B), in contrast to the more faint and non-
overlapping staining for ras and CD44 in MCF-7 (C) and MCF-1OA-Neo cells @) used
as controls. IgG was used as a control in these experïments (E).
Fig. III. 10.
Co-immunoprecipitation of RHAMM, erk, and CD44 Antibody-2, anti-erk, and Herrnes3
were used against RHGMM, erk, and CD44, respectively, for both immunoprecipitation
(IP) and probing (TB) of the blots. The anti-RfiGMM antibody co-immunoprecipitated
erk, and the anti-erk antibody co-immunoprecipitated the 63 kDa RHAMM isoform, to
greater extents in the MDA-MB-231 ceiis than in the MCF-7 cells (A). More co-
immunoprecipitation of RHAMM and erk oçcurred in the MCF-1OA-NeoT2 (ceus
transfected with mutant active ras) than in MCF-IOA-NeoN (cells transfected with
normal ras). Antibody-2 CO-immunoprecipitated 116 kDa and 85 kDa CD44 isofoms
only in MDA-MB-23 1 cells and in cells transfected with mutant active ras (B and C).
Anti-CD44 antibody CO-immunoprecipitated both the 85 kDa and 63 kDa RHAMM
isoforms found in greater abundance in MDA-MB-23 1 cells and MCFlOA-NeoT2 than in
the MCF-7 and MCFlOA-Neo control ce11 Lines @). In al1 expenrnents, MOCK was used
as negative control, where rabbit IgG, or mouse IgG was used instead of anti-RHAMM,
anti-erk or anti-CD44
B IP: RHAIMM, Ab-2 - IB: CD44 2
i Z S 4 kDi Z Y 5! 120 -c
8 7 4
64 - 53 4
Fig. III. Il.
Time-lapse cinemicrography of MDA-MB-23 1 cells and ras-transfected MCF-1 OA cells.
MDA-MB-231 locomotion at (60.21627 Cun/hour) was significantly blocked by
treatment with anti-RHAMM antibody-2 or anti-CD44 (Hermes3) antibody, but mùring
of these antibodies did not show an additive effect on their motility (A). PD098059
compound, a MEK inhibitor, also decreased MDA-MB-231 ce11 motility compareci to
cells treated oniy with the diluent, DMSO (B). The random locomotion of MCF-ZOA-
Neo-2T cells was decreased upon treatment with anti-RHAMM antibody-2 or anti-CD44
antibody, and mixing of these antibodies did not show an additive effect (C). Treatment
of MCF- IOA-Neo-2T cells with the PDû98059 compound decreased their motility to
similar levels as did the anti-RHAMM antibody @). Results shown are from triplicate
experiments. Asterisks indicate that differences in mean locomotion between treatment
with specific antibody and treatment with IgG control were statisticaily significant at
p<0.05. Ab ('s), antibody or antibodies.
MCF-10A mutant active ras trdected
CHAPTER IV
DISCUSSION
Whereas the signal transduction pathways involved in ceii cycle regdation have
been well studied, those coordinathg ce11 motility have only recently received attention.
Cell surface receptors, such as integrins and growth factor receptors including the protein
tyrosine kinase src and the serindthreonine kinase ERK, have been shown to play roles in
ce11 motility and invasion (Patel et al., 1998; Zeigler et al., 1999). Recently, a novel
group of extracellular matrix receptors belonging to a class of hyaluronan binding
proteins called the hyaladherins have also been implicated in tumor ce11 motility (Kohda
et al., 1996). Two of these hyaladhenns, RHAMM and CD44, have been studied in the
context of human cancer (Wang et al., 1998; Pilarski et al., 1998; Herrera-Gayol and
Jothy, 1999). The purpose of this study was to examine the contribution of these
hyaladherins to the motïlity of breast cancer ceil lines which had been previously
characterized with respect to their invasiveness in nude mice (Thompson et al., 1992).
Specifically, we demonstrated relationships arnongst RHAMM and CD44 expression,
overexpression/mutation of ras proto-oncogene, and activation of the ras/MAP kinase
pathway, to breast cancer c d motility.
IV.1 Ras and raderk Signaling Cascade in Breast Cancer Development
Breast cancer is a complex and heterogeneous disease that is the most common
world-wide cause of malignancy in women (Fisher et al., 1997). Although experimental
studies suggest that aberrant ras function can promote the malignant progression of
human breast epithelial cells, the occurrence of mutant ras g e n s in breast tumors is
infrequent (5%). The infrequent occurrence of activating ras mutations in breast
carcinomas indicates that any aberrant function of the proteins on the ras signaling
pathway, which contributes to breast cancer progression, occurs via another de-regulating
mechanism. Constitutive activation of ras signaling pathways may occur by at least nuo
mechanisms. F i t , overexpression of other componeats, both upstreaxn (e.g.
overexpression and upregulation of HEIU/neu/erbBZ receptor tyrosine kinase) (Shackney
et al., 1998; Ross et al., 1999), ancilor downstream (e-g. erk) (Sivaraman et al., 1997;
Wang et al., 1998; Salh et al., 1999) of ras may occur. Second, deregulaîed function of
regulatory proteins for ras or of other GTPases such as h o , which are essential for ras
transformation, may promote s ignahg through ras (Mangues et al., 1998). Therefore,
chronic activation of the ras signaling pathway by aiternate means is aiso involved in
breast carcinomas.
The three human ras proto-oncogenes encode four closely related 21 kDa
proteins, designated H-ras, K-ras, N-ras, and m-ras, whose activities are controiled by
guanine nucleotide binding (Boume et al., 1990a; Boguski and McCormick, 1993;
Matsumoto et al., 1997). Ras proteins are responsible for regulating the flow of
information that is triggered by diverse extracellular signals impinging upon a variety of
ce11 surface receptors (Lewis et aL, 1998). The relay of signds from these receptors via
ras proteins ultimately controls the activities of nucIear transcription factors which induce
the expression of key genes regulating ce11 growth and differentiation (Kyriakis et al.,
1999) (Fig. Ne 1.). Ras proteins shuttle between active GTP-ùound "on" states and
inactive GDP-bound "off" states by means of a regulated GTP/GDP cycle that is
controlied by at least two types of regulatory nucleotide exchange factors (Bourne et al.,
1990a; Boguski and McCormick, 1993) which serve to promote the formation of active
ras-GTP. Oncogenic ras proteins persist chronicaily in the GTP-bound state, thus leading
to the constinitive activation of downstream growth regulatory signals (Fig. IV.1.).
Figo IV. 1. b mgdates a cascade of kinases. A linear pathway where ras fûnctions downstream of receptor tyrosine kinases (RTK) and upstream of a cascade of s e ~ e / t h r e o ~ n e kinases (Ra.6MEOER.K) provides a complete Iink between the ceIl surface and the nucleus. Activated erk proteins also phosphorylate and thereby activate transcription factors such as Elk-1. Activated erks also phosphorylate substrates in the cytoplasm, including the Mnk kinase, and thus contribute to translation initiation of mRNAs with sauctured 5'- untranslatecl regions. (Ciark a d Der, 1994)
PTK receptors, such as HERUneu (Tari et al., 1999) and c-MET (Hiscox and
Jiang, 1999), promote mitogenic responses in breast cancer cells and these receptors
regulate cellular functions that are involved in the acquisition of an invasive phenotype
such as modulation of cellular attachments, proteolysis of extracellular matrix, and
directional migration. For instance, in the case of c-MET receptor, mature, biologically
active hepatocyte growth factor, aiso known as scatter factor (HGFISF) elicits its
response by binding to the Met tyrosine kinase receptor at the ceil surface (Bottaro et al.,
199 1 ; Naldini et al., 199 1). Subsequent activation of numerous signaling pathways then
results in the reguiation of a wide range of biological activities of tumor ceUs including
stimulation of motility, migration, growth, angiogenesis and invasion (Hiscox and Jiang,
1999). One of the pathways involved in the tumorigenic activity of mutant c-Met
molecules has been shown to occur through the raJMAP kinase pathway in mouse
metastatic mammary carcinoma ceils (Jeffers et al., 1998).
Overexpression and amplification of HER2 oncogene, another PTK receptor, bas
been found to correlate with poor survivai of breast tumors (Peles et al., 1993; Vargas-
Roig et al., 1999). In addition, HERuneu oncogene is also associated with high
tumorigenicity and the metastatic phenotype of both breast and ovarian carcinoma ce11
lines (Berchuck et al., 1990). Cells expressing high levels of CD44 and pl85 - bind
hyaluronic acid with high affinity (Zhu et al., 1996). Furthemore, mammary tumors
initiated by HEWneu have high levels of active ErkIMAP kinase and their anchorage
independent growth is strongly inhibited by PD098059 (Amundsdottir et al., 1998).
In addition, RTK have been reported to induce a number of extracellular matrix-
degrading proteases including MMP-9 via activation of MAPK pathway (McCawley et
al., 1998; Reddy et al., 1999). MMPs are a family of stnicturally related enzymes that
together c m degrade al1 components of the extracelIular matrix and are known to be
important in tumor ce11 invasion (Stelter-Stevenson et al., 1993). Recentiy, it has been
shown that the invasive breast tumor cells express high levels of MMP-9 (Reddy et al.,
1999; Y u and Stamenkovic, 1999) whicb associates with ce11 surface receptors such as
CD44 to degrade collagen type N leading to tumor ce11 invasion and metastasis
(Bourguignon et al., 1998a; Yu and Stamenkovic, 1999). A possible mechanism by
which sustained activation of MAPK could result in MMP-9 induction is through
regulation of essential transcription factors such as c-Fos. Expression of this immediate-
early gene is dependent on MAPK activation, and furthemore, phosphorylation of c-Fos
by MAPK enhances its activity leading to transcription activity and AP-1 dependent
expression of the MMP-9 gene, and breast tumor celi motility and invasion (Hayashi et
al., 1999; McCawley et al., 1999; Mira et al., 1999).
IV. 2. CD44 and RBAMM, Co-receptors that Mediate Tumor CeU
Moolity through the RPs/MAP Kinase Pathway
The hyaluronan receptors, CD44 and RHAMM, have been impiicated in breast
tumor growth and metastasis by mechanisms that riemain pooriy understood (Wang et al.,
1998; Herrera-Gayol and Jothy, 1999), but severai observations suggest their
involvement in the ras/ MAPK signaling pathway. These are: 1) RHAMM expression
correlates with erk and ras in human breast tumor biopsies (Wang et al., 1998); 2)
RHAMM is an erk binding protein in murine fibroblasts (Zhang et al., 1998; 1999); 3)
RHAMM regulates signaling through ras in munne fibroblasts (Hall et al., 1995); 4)
CD44 expression is regulated by ras (Hofmann et al., 1993); and 5) CD44 associates with
HEWneu, which is up-regulated in the activated ras pathway in breast cancer cells
(Bourguignon et al-, 1997; Kaiish et al., 1999).
CD44 mediates adhesion and migration of a variety of ce11 types upon
hyaluronan substrats (Thomas et al., 1992; Faassen et al., 1993; Goebeler et al., 1996;
Okada et al., 1996; Trochon et al., 1996; Knudson, 1998). This receptor is required for
breast tumor ce11 invasion through other rnatrix components (Knudson, 1998; Herrera-
Gay01 and Jothy, 1999). This latter ability may be related to interactions between CD44,
or its modified variant forms, and receptors for growth factors or integrins such as
HEWneu andor c-met that collectively control signaiing pathways regulating ce11
motilityhvasion (F3ourguignon et al., 1998b; Pais et al., 1998; Katagiri et al., 1999' van
der Voort et al., 1999). In addition to the outer domains of CD44 that act as an adhesion
receptor for HA (Aruffo et al., 1990) and CO-receptor for HER2/neu (Zhu et al., 1996)'
the cytoplasmic domain of CD44 is linked to the actin cytoskeleton via ERM proteins
(Nearne et al., 1995) (Fig. 1. 4.). Possibly these interactions localize CD44 to
invadopodia and it's association with MMP-9 (Bourguignon et al., 1998a; Yu and
Stamenkovic, 1999), a collagenase that is regulaîed by the rasmiLAP kinase pathway and
has been impiicated in cell motility and invasion (Okada et al,, 1997; Llorens et al,, 1998;
Maeda et al., 1998; Hayashi et al., 1999; McCawley et al., 1999; Mira et al., 1999)' and
may contribute to the requirernent for CD44 in ce11 invasion.
EWAMM is a hyaladherin required for ce11 motility and invasion of a variety of ce11
types. Ce11 surface RHAMM has been shown to be required for invasion of human breast
cancer cells through matrigel in vitro (C. Wang, personal communication) and for
motility of malignant B cells (Gares et al., 1998; Pilarski et al., 1999). Cell surface and
in tracelMar forms of RHAMM are required for signaling motility through mutant active
ras in fibrobiasts (Hall et al., 1995; Zhang et al., 1998) for promoting ceil motility
following injury (savani et al., 1995a, 199%) and in response to growth factors such as
TGF-P (Samuel et al., 1993). The appearance of RHAMM expression early after celi
plating within ce11 IamelIae (Zhang et al., 1998) and the role of RHAMM in neurite
extension (Nagy et al., 1998) suggest that RHAMM is involved in ce11 extension and
formation of larnellae dunng the motïie cycle. RHAMM is, like CD44, also present
within invadopodia (Harrison and Turley; 1999) and regulates AP-1 activation (Cheung
et al., 1999) as well as expression and release of MMP-9 (Zhang et al., 1999).
The highly invasive and metastatic celi line, MDA-MB-231, was chosen for this
study based on previously published data describing its aggressive biological behavior
(Thompson et al., 1992; Bae et al., 1993; Sommers et al., 1994). Like MCF-7 cells,
MDA-MB-23 1 cells were derived from a mammary epithelial breast carcinoma, but
unlike MCF-7 cells, MDA-MB-231 cells express mutant K-ras and activated H-ras.
Moreover, MDA-MB-23 1 cells are estrogen receptor-negative. vimentin-positive, and are
invasive and metastatic in nude mice. This ceil line is able to synthesize hyaluronan
(Heldin et al., 1996) and expresses high levels of surface CD44 protein (Culty et al.,
1994; Ponta et al., 1995) (Table W . 2.). MCF-1OA cells are immortalized, estrogen
receptor negative breast epithelial cells derived from human fibrocytic mamrnary tissue
(Soule et al., 1990) and were transfected with either ras oncogene (Mm-IOA-NeoN) or
proto-oncogene (MCF-IOA-NeoT2) as stated in Basolo et al. (1991). Unlike the MCF-
10A-Neo or the MCF-IOA-NeoN cells, the MCF-IOA-NeoT2 cells exhibit anchorage-
independent growth, are estrogen negative cells, and are invasive in vitro and tumorigenic
in nude mice. Therefore, these highly tumongenic human breast epithelial ce11 lines were
selected as they exempli@ the behavior of a clinicaily aggressive human tumor (Table
IV. 2.).
It was demonstrated here that human breast cancer ce11 lines express RHAMM at
the ce11 surface and intracellularly, and that the levels of RHAMM expression correlate to
the previously determined invasive and metastatic phenotypes of these cells in nude rnice
(Thompson et al., 1992). In contrast to the results obtained by Assmann et al. (1998),
who reported exclusively intrace1luIa.r RHAMM localization, we found RHAMM
Table 2 Characteristics of human breast epithelial cell lines
2 Cell Line TT' ~ o t i l i t y HA' E: vin5 BCCA~ E-cad7 811 ~ 4 ) hs-mut'' H-ras" ~ - m " fin lnv. M&
' Tl' tumor type, AC, adcnocarcinoma (7'hompson et al., 1992) 2~an&m ce11 motility measund by using a computerized timelapse image anilyois system ()rm/hr). 3 HA production in culturc ( p L / 1 0 ~ cells) MCF-lOAT2 cells are capmble of binding and iipPLe of hyaluronan (Giunciuglio et al., 1995).
4 Estrogen recepior slatus: MDA-ME-23 1& MCF-7 (Thompson et al, 1992); MCF-1OA (Pilat et al,, 19%)
5 lntermediate filament potein vimentin MDA-MB-23 l& MCF-7 (Thompson et al, 1992)
6 lnvasive activity in Boyden chamber chernoinvasion assay: MDA-MB-23 l& MCF-7 (Thompson et al, 1992); MCF4OA (Giunciglio et al., 1995)
7 Ecadherin/uvomorulin expression: MDA-MB-23 1& MCF-7 (Sommers et al, 1994); MCF- 1OA (Zhong et al,, 1997), 3 1 integrin expression (fm Sommen et al, 1994). 9 P4 integrin expression (from Sommers et al, 1994).
'O ras poto-oncogen mutation (Bos, 1988) "H-ras 1.2 kb niRNA genc ampüfication relative to normal 18 1 cells: MDA-MB-23 l& MCF-7 (Zajchowski et al., 1988); M C P IOA (Soule ct (il. (1 990) ' 2~- ras 1.2 kb mRNA gene amplification relative to normai 18 1 a l l s (Zpjchowski et al., 1988). 13
Tumorigenesis, local invasion and metastasis in athymic nude mouse (Ncr nidnu): MDA-MB-23 1Eé MCF-7 ( Thompson et al, 1992); MCF-IOA (Giunciuglio et al., 1995).
expression on the surface of both MDA-MB-23 1 and MCF-7 cells using FACS malysis;
MDA-MB-23 1 cells were shown to express the highest Ievel of ce11 surface RHAMM.
These results are consistent with the previous fmdings indicating that ce11 surface
RHAMM appears to be less dynamic over time and more constitutively expresseci with
malignanc y (Crainie et al., 1999) and in ras-transformed murine fibroblasts (Zhang et al.,
1998, Cheung et al., 1999). The apparent discrepancy between our results and those of
Assmann and coworkers may have been due to one or to a combinaîion of several factors.
For instance, the MDA-MB-468 cells used by Assmann et al. (1998) have a similar
mutational background as MCF-7 cells, are not invasive or metastatic in nude mice, and
do not harbor a ras mutation (Thompson et al., 1992). Consistent with their finding, we
detected low levels of RHAMM on the surface of MCF-7 cells. Furthermore, the
transient nature of RHAMM expression, which occurs soon after plating but maximdy
before confluency of murine fibroblast cells (Zhang et al., 1998, Cheung et al., 1999),
requires that cornparisons between studies be made over time after ceil plating.
Differences in the rnethods used for FACS analyses for detecting ce11 surface RHAMM
may also have contributed to the difierent findings. In contrast to Assmann et al. (1998),
we did not treat the cells with paraformaldehyde andor sodium azide before antibody
treatment. Furthemore, because trypsinization of cells before FACS analysis leads to
loss of RHAMM from the ce11 surface, we have used a proprietary dissociation reagent
that contains no trypsin. Throughout al1 of Our experiments presented here, we used cells
at 50% confluency; the degree of confiuency at which cells were studied by Assmann et
al. ( 1998) was not clearly defined. Furthermore, whereas we present data of ce11 surface
RKAMM expression utilizing three different anti-RHAMM antibodies specific for
different regions of RHAMM protein, detection of cytoplasmic and nuclear RHAMM by
Assmann et al. (1998) was performed using a single anti-RHAMM antibody directed
against an epitope found in the interior of the RHAMM protein. Possible masking of this
interna1 epitope due to the secondary structure of RHAMM might prevent its detection.
Both RHAMM and CD44 have been reported to coordinate motility of various
ce11 types (Nagy et al., 1998; Herrera-Gayol and Jothy, 1999; Pilarski et al., 1999). The
results of the present study are the first to show that although both RHAMM and CD44
coordinate the motility of ras-transfected and cancerous breast epithelial cells, they do not
appear to exert additive effects. For instance, both RHAMM and CD44 antibodies
significantl y blocked the motility of MDA-MB-23 1 cells and M m - 1 OA cells transfected
with mutant active ras. However, combination of the two antibodies did not further
decrease the motility these ceus. Coordination is suggested by: 1) the non-additive effect
of the antibodies on ce11 motility; and 2) CO-association of receptors in ce11 processes.
RHAMM and/or CD44 are obviously not the only ce11 surface receptors responsible for
the motility of these celis, as other receptors such as urokinase plasminogen activator
receptor (uPAR), which is also regulated by erk kinase (Nguyen et al., 1998) take part in
enhanced ce11 motility (Andreasen et al., 1997). Results presented here indicate that the
motility of breast cancer cells and r a s - t r a n s f o d cells is significantly reduced upon
treatment with a MEK inhibitor, suggesting the direct involvement of the erk kinase
pathway in the motility of breast cancer ceils consistent with previous studies of the role
of erk in motility of other cells (KIemke et al., 1997; Reszka et al., 1997). The
concentration of PD08059 used in this study (5Op.M) is equal to that reported to
completely inhibit MEKl in vitro (Alessi et al., 1995). Previous studies suggest that
PD098059 interferes with growth factor-induced erk activation and MMP-9 expression,
suggesting that receptor tyrosine kinase-mediated MMP-9 induction requires a MEKI-
dependent pathway (Gum et al., 1997; McCawley et al., 1999). In one mode1 system
where cells displayed constitutive activation of MAPK, the accompanying up-regdation
of MMP-9 expression was dependent upon AP-1 response element sites within the MMP-
9 promotor (Qui and Green, 1992; Himelstein et al., 1997). Furthemore, recent
observations indicate that CD44 serves to anchor MMP-9 on the celi surface (Yu and
Starnenkovic, 1999), and disruption of the function of ce11 surface RHAMM by antibody
blocking inhibits MMP-9 activity (Zhang et al., 1999). Interestingly, both the invasive
MDA-MB-23 1 cells and mutant active ras-transfected MCF-IOA cells studied here have
previously ken shown to express high levels of MMP-9 on the ce11 surface, as compared
to their non-invasive counterparts, MCF-7 and MCF-LOA-Neo (Toth et al., 1997;
Bourguignon er al., 1998a, 1998b). Ce11 surface expression of MMP-9 would ultimately
lead to the degradation of type TV collagen and therefore to the ability of hlmor cells to
invade and metastasize. From these findings, it seems reasonable to propose that
RKAMM and CD44 play synergistic roles in controiling MMP releaselfunction
mediating Nmor ce11 motility and invasion (Fig. W . 2.). The precise role of RHAMM in
suc h a signaling cascade, however, remains to be determined,
IV. 3. RHAMM and CD44 Expression are Linked to ras Overexpdon
and erk Activation in Breast Cancer C e b and Bre~st Epithelial C e k
Transfected with Mutant Active ras
In this study, RHAMM and CD44 expression correlated with over~xpression of
ras and activation of erk in MDA-MB-231 human breast cancer cells and in MCF-1OA
cells transfected with mutant active ras. Although a correlation of active erk to CD44 is
novel, the findings that RHAMM overexpression, a regutator of ras (Hal1 et aL, 1995)
and erk signahg (Mohapatra et al., 1996; Zhang et al., 1998), significantly correlated to
active erkl was consistent with recent studies by Wang et al. (1998) indicating that erk
expression by itself was not significantly associated with poor prognosis of breast cancer,
but overexpression of both RHAMM and erk were indicative of lymph node metastasis
and high tumor grade. Moreover, the expression of both the 85 kDa and 63 kDa isoforms
of RHAMM was up-regulated with ras overexpression both in the MDA-MB-23 1 ceiis
and in the mutant active ras transfected MCF-1OA cells, whereas the 43 kDa RHAMM
was not correlated with ras overexpression. Recent studies of the RHAMM promotor
region indicated the presence of an AP-1 transcription factor binding site (Assmann et al.,
1998). In addition, RHAMM is required for activation of erk kinase cascades and AP-1
through PDGF activity (Zhang et al. 1998; Cheung et al., 1999). Hence, the correlation
between RHAMM overexpression and the presence of overexpressed or mutant active ras
in the two groups of ce11 lines studied here is consistent with a previous report from Our
laboratory noting this same correlation in breast cancer biopsies (Wang et al.. 1998). and
E2HAMM overexpression has often (Hall et al., 1995) but not always (Hofmann et al.,
1998) been linked to mutant active ras expressed in munne fibroblasts.
Previous data indicated the involvement of CD44 in the raslerk sigaaling and in
human breast cancer development. For example, an AP-1 transcription factor binding site
has been identified in the CD44 gene prornoter that is activated by c-H-ras activation in
rat embryonic fibroblasts and results in the expression of CD44 i s o f o m as weli as in
increased expression of CD44 mRNAs (Hofmann et al., 1993). Our results indicate that it
is the standard forrn of CD44 correlating to a reported molecular weight of 85 kDa
(Bourguignon et ai., 1998a) that is overexpressed both in MDA-MB-231 ceils and in
MCF-1OA cells transfected with mutant active ras. This CD44 isofonn has been shown to
bind to p 185 - (Bourguignon et al., 1998b) .
Collectively, these results suggest that an interplay occurs between signals
generated from ce11 surface RHAMM and CD44s variant, and those signals regulated by
intracellular RHAMM forrns and CD44 domains, ail of which involve growth factor
receptor mediated ras/MAP kinase activation and hence have impact upon tumor ceil
motility (Fig. N. 2.).
IV. 4. REKAMM Co-associates with erk in MDA--1231 Ceh and
MCF-1OA Cek Transfected wïth Mutant Active ras
Aithough expression of both the 85 kDa and the 63 kDa RHAMM isoform were
up-regulated with ras overexpression both in the MDA-MB-231 cefls and in the mutant
active ras-transfected MCF-1OA cells, CO-immunoprecipitation results showed that erk
was bound by the smaller (63 kDa) RHAMM isoform and not by the standard (85 kDa)
RHAMM isoform. The 63 kDa RHAMM isoform was not detectable in MCF-7 cells, but
when an increased amount of total protein was used for CO-irnrnunoprecipitation, this
isoform was CO-immunoprecipitated with erk in MCF-7 cells and also to a smaller extent
in MCF-1OA cells transfected with empty vector only. However, the de- of co-
association of erk and RHAMM depended on the mutational background of the cells
used, where more RHAMM associated with erk in the MDA-MB-23 1 cells and MCF-
10A cells transfected with mutant active ras. Furthermore, confocal analyses were
indicative of CO-association of RHAMM and erk in the nucleus of MDA-MB-23 1 cells
and MCF- 1 OA cells transfected with mutant active ras. Interestingly, treatment of these
cells with the MEK inhibitor, PDû9û859, abolished the ;tccumulation of both RHAMM
and erk in the nucleus and instead the CO-localization was seen in the perinuclear regions
of these cells. Recent studies by Brunet et al. (1999) indicated that nuclear translocation
of erk is required for growth factor-induced gene expression and ce11 cycie entry by Ek-
dependent gene transcription which leads to DNA replication in response to growth
factors. McCawley et al. (1999) has s h o w that sustained activation of the mitogen-
activated protein kinase pathway is required for expression of MMP-9 through AP-1
regulated genes. In addition, Balmanno and Cook (1999) suggested that sustained
activation and translocation of erk into the nucleus is essential for neurite growth factcr
(NGF)-induced neuronal differentiation of PC12 (pheochromocytoma) cells.
Furthermore, nuclear erk is known to bind AP-1 sites to increase the transcription activity
of growth-related genes, the expression of which leads to ce11 motility and invasion
(Karin, 1995; Seger and Krebs, 1995, Zhou et al., 1998). Other workers in my laboratory
have previously shown that RHAMM is required for ce11 cycle progression through the
G2/M transition (Mohapatra et al., 1996), and ongoing studies suggest that active erk
associates w ith intracellular RHAMM in the rnitotic spindles of ras-transformed human
breast cancer ceils (R. Harrison, persona1 communication). Recently, Huileman and
colleagues ( 1 999) showed that p42/p44 MAPK nuclear translocation and retention
requires both MAPK activation and neosynthesis of nuclear anchonng proteins which are
expressed transiently. It could be speculated that RHAMM may facilitate erk entry into
the nucleus and it may not o d y play a crucial role in sustainhg nuclear erk activity
leading ultimately to ce11 motility which may not require transcription of genes (Kiemke
et al., 1997; Hoshino, 1999), but it may dso take part in ceil division and hence may act
as an oncogene (Hdl et al., 1995).
IV. S. RHAMM Co-Associates with CD44 in Breast Cancer Ceils and
Breast Epitheliai CeUs Transfected with Mutant Active Ras
RHAiMM CO-immunoprecipitated with two CD44 isoforms - an 85 kDa isoform
which represents the standard form of CD44 and a 1 16 kDa isoform which likely
represents the CD44v10 isoform. Both of these CD44 isoforms have been shown to be
expressed in MDA-MB-23 1 cells (Culty et al., 1994) and are associated with increased
tumorigenicity and invasiveness of breast cancer cells (Bourguignon et al., 1998a, 1998b;
Kalish et al., 1999). Likewise, the CO-immunoprecipitation of two RHAMM isoforms (85
kDa and 63 kDa) seems to be associated with the mutational background of breast
epithelial cells, since only the 85 kDa RHAMM isoform was CO-irnmunoprecipitated in
normal MCF-1OA cells whereas both RHAMM isofonns CO-immunoprecipitated with
CD44 in both the MDA-MB-23 1 cells and MCF-IOA cells overexpressing ras.
Interestingly, onIy in the MDA-MB-231 cells was the 48 kDa RHAMM isoform co-
immunoprecipitated with CD44 The level of co-imrnunoprecipitation of RHAMM with
CD44 was higher in invasive MDA-MB-231 ceils and MCF-1OA cells transfected with
mutant active ras as compared to MCF-7 ceUs or MCF-1OA celis transfected with empty
vector. This could have been due to higher expression of both RHAMM isoforms in these
cells, as shown by Western andysis, and hence more RHAMM is able to interact with
CD44 The results of immunostaining for RHAMM and CD44 in MDA-MB-231 cells
indicated tbat most RHAMM and CD44 CO-association occurred in the perinuclear
regions of these cells, although some immunostaining was also detected in the cellular
processes and in the vesicies found close to the ce11 membrane. However, treatment with
0.1% Triton-X ablated staining for RHAMM in the cellular processes and under these
conditions, we were able to observe the RHAMM and CD44 immunostaining onIy in the
perinuclear regions only. Other laboratories have shown that RHAMM and CD44 are
found in close association in the endocytic vesicles of astrocytoma cells, and that this
association is required for HA uptake (J. Rutka, personal communication). Our results
show that RHAMM and CD44 interact in the MDA-MB-23 1 cefls and MCF- 1OA cells,
both of which bear ras mutations. Hence, the interaction of CD44 and RHAMM appears
to predoniinate when ras is overexpressed. Although the exact regions of RHAMM
interacting with CD44 and the role of this interaction remains to be investigated, this
association couId add to the invasive phenotype of breast cancer cells.
IV. 6. A Model of HA and its Receptors in Werk Sipaiing and Breast
Cancer Development
Considerable data suggest that the raderk signaling pathway is involved in breast
cancer progression. HA and its receptors RHAMM and CD44 regulate this signaling
cascade and are Wcely implicated in breast cancer development. Although CD44
hyaluronan interactions have been show to activate AP-1, little is known about how this
signal is transmitted. It is emerging that CD44 may exert its effect on AP-1-regulated
genes by acting as a co-receptor for growth fxtor receptors such as c-Met or HEWneu
(Bourguignon et al., 1998b; van der Voort et al., 1999) to enhance activation of the erk
kinase cascade, thereby indirectly promoting MMP-9 expression. CD44 may aiso affect
MMP-9 activity by enhancing expression of MMP-2. which is able to activate pro-MMP-
9 (Takahashi et al., 1999) Recently, two groups demonstrated that CD44 associates with
MMP-9 at the site of invadopodia (Bourguignon et al., 1998b; Yu and Stamenkovic,
1999) and this association is required for the maintenance of invadopodia, the ability of
MW-9 to degrade collagen type N, and the ability of tumor cells to invade in vitro. The
ability of CD44 to bind to HA may also act to corral growth factor receptors within
larnellae tips where invadopodia or podosomes occur (Yu and Starnenkovic, 1999),
permitting local regulation of signaling pathways such as erk kinase which c m aiso
contribute to rnotility independent of gene transcription (Klernke et al., 1997).
Both the ce11 surface and intracelluIar forms of RHAMM act on the src-ras-erkl
kinase cascade (Hail et al., 1994; HaiI et al., 1995; Zhang et al., 1998). Ce11 surface
RHAMM, like CD44 participates in the binding of hyaluronan to the cell surface
(Entwistle et al., 1996; Hofmann et al., 1998) in many but not on aU ce11 types. This
interaction appears to activate src, resulting in modification of the actin cytoskeleton
(Hall et al., 1996; Cheung et al., 1999). Ce11 surface RHAMM, which is not an integral
membrane protein, may achieve this effect by its association with caveoli (Piiarski et al.,
1999) andor its association with growth factor receptors such as PDGF (Zhang et al.,
1998). Since ce11 swface RHAMM is usually transientiy expresseci, its role in the motile
cycle may be to initiate it rather than to sustain it. As mentioned earlier, RHAMM exists
as several isofomis, and RHAMM(AI -5) is transiendy expresseci even in ras-transformed
cells (Zhang et al., 1999). When constitutively overexpressed, RHAMM(A1-5) activates
erk 1 kinase, activates AP- 1, and enhances expression of MMP-9. Interestingly,
RHAMM(A1-5) is present within podosomes where it CO-localizes with both erkl and
MEKl (Harrison and Turley, 1999)- Activation of erk kinases have, in partidar, been
linked to cell motility and invasion (Klemke et al., 1997; Herrera, 1998; Jeffers et al.,
1998; Tanimura et al., 1998). Since the erk kinase cascade clearly reguiates MMP-9
expression via AP-I activation in breast cancer cells (Tremble et al., 1995; Gum et al.,
1997; McCawley et al., 1999) part of the effect of hyaluronan on ce11 motility and on
invasion is likely mediated, in part, by this collagenase. The ce11 surface isoform of
RHAMM which appears to be labile is a peripheral protein, unlike CD44, which has a
transmembrane domain (Lesley et al., 1993). Therefore, for signaling events to occur,
RHAMM may associate with a docking protein, such as CD44 (Welsh et al., 1995) (Fig.
IV. 2.), andor perform a smcnual hinction, such as by changing the conformation of
transmembrane proteins in a manner that modifies their signaling profile, For example, it
has recently been shown that ce11 surface RHAMM modifies the ability of PDGF receptor
to phosphorylate proteins on tyrosine (Zhang et al., 1998). Since both CD44 and
RHAMM have previously been shown to regulate ras activity, and since CD44 is
involved in invadopodia formation and gelatinase B release (Bourguignon et al., 1998b),
interaction between RHAMM and CD44 may enable the transmission of an extracelluiar
signal regulating cell motility.
In summary, the hyaladherins CD44 and RHAMM regulate signaling pathways to
control ce11 motility and invasion. One key pathway that is involved in this regdation is
the raserk kinase cascade that has previously been s h o w to resuit in enhanced
expression of MMP-9. CD44 and RHAMM might co-ordinate signaling through this
pathway to regulate expression of the collagenase, to regulate the formation of sites of
MMP release, invadopodia or podosomes, and to control activity of MMP-9 at these sites
of release. These propeaies are proposed to be responsible, io part, for the role of these
hyaiadherins in tumor progression.
Fig. IV. 2. A Mode1 of HA and its Receptors in the raslerk Signaüng Pathway
IV. 7. Future Studies
While data obtained fiom the M-Sc. project descnbed in this thesis provide some
insight into the roles that RHAMM and CD44 may play in human breast cancer
development, other questions are raised as weil. There is as yet no direct evidence
indicating that RHAMM is an oncogene in human cells, although RHAMM
overexpression has been shown to transfonn murine fibroblasts (Hall et al., 1995).
Changes of cell locomotion, invasion, turnongenicity, and metastasis as weii as CD44
expression could be examined in human breast cancer cells following: i) transfection of
RHAMM cDNA and overexpression of RHAMM protein; ü) down-regdation of
RHAMM using antisense strategies; or iii) blockade of RHAMM function using mutant
RHAMM (Hail et al., 1995). Furthermore, it would be very usefid to determine whether
specific RHAMM antibodies or peptides, fusion protein, or antisense oligonucleotides
could affect breast cancer cell growth and dissemination in an animal model. This study
will provide the basis for future use of RHAMM as a specific therapeutic target in human
breast cancer.
Although the findings in this thesis indicate that the level of RHAMM and CD44
protein expression correlate to breast cancer ce11 invasiveness phenotype, future studies
could be directed towards the study of the regdation of RHAMM and CD44 expression
at the transcriptional and translational levels. Furthemore, in munne fibroblast cells, the
shorter isoforrn of RHAMM (RHAMM(A1-5)) is an oncogene (Hall et al., 1995). Since a
63kDa isoform is upregulated in both MDA-MB-23 1 cells and in MCF-1OA cells
transfected with mutant active ras, elucidation of the role of this isoform in invasion and
metastasis is necessary.
Cell surface RHAMM expression is correlateci with the aggressive pbenotype of
breast cancer cells. However, more studies could be performed to identifi the isoforms
that are expressed on the ceii surface as compared to intracellularly, or to determine if the
isoforms differ in their affinities toward CD44 and erk binding. Moreover, the molecular
switch that leads to constitutive expression of cell surface RHAMM in cancerous cells as
compared to its transient nature in non-cancerous cells has yet to be discovefed.
Although results presented in this thesis demonstrates that interaction of RHAMM
and CD44 occurs in vitro, further investigation is needed to determine the domains and/
or regions of each molecule responsible for this interaction or if other intermediates such
as erk are required to faditate this interaction. For example, what are the CD44 isoforms
that bind RHAMM? Does RHAMM bind directly to CD44? Does RHAMM bind to
MMP-9? In addition, although we now know that these HA receptors interact primarily
when ras is constitutively active, it will be usehl to study the exact role of these proteins
in the raderk pathway by using other inhibitors of intermediaries in the pathway. Two
such inhibitors which have recently become available are ras-specific inhibitor (famesyl
transferase inhibitor- 1) and erk inhibitor (PD 184352) compound. inhibition studies using
these reagents could provide more information on the roles of RHAMM and CD44 in this
pathway and could lead to novel therapeutic approaches.
Another gap in Our understanding is the role of RHAMM in the nucleus of ras-
overexpressing cells. Initial studies in this area are suggestive of the role of RHAMM in
spindle organization during mitosis in the ras-transformeci breast epithelial cells (R.
Harrison, personal communication) and the role of RKAMM in nuclear HA uptake (L.
Collis, personal communication) in breast cancer ceils. Future studies could therefore be
directed toward deteminhg whether nuclear HA lm aiization is dependent upon nuclear
RHAMM and its interaction with nuclear erk,
CHAPTER V
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CHAPTER VI
APPENDIX
The Drosophila RHAMM Homologue
BACKGROUND
RHAMM is a hyaluronan binding protein which was originally purificd from locomoting
murine 3T3 fibroblasts (Hartwick ct al., 1992) and chick embryo heut fibroblasts (Entwhistlt et
al., 1995). This 60 kDa protein was found to be an HA binding component of a soluble protein
cornplex. RHAMM functions as a motility mxptor for KA in numemus c d types. including
fibroblasts (Savani cc ai, 1993). rmootb muscle œIis (Savani a 4.. 1993). macfopbages (Sunuel
et ai.. 1992). T lymphocytes flurley et al.. 1991). spennat~~ytes flurky et ai.. 1992) ami
neumns (Tudey et J., 1992). as vell as mrligiunt ccilr such as m-tmmf" fibrioblasa
(Turley et al.. 1991). multiple rnyclomi B celis fluriey et d.. 1991). aad kcrrt cricinomi aîi
as restenosis and tumor progressicm (Wmg et d.. 1998).
S t n i c W y . RHAMM is enooded by a single gene loca<cd on human chromosorne
5q33.2qter and on mouse chromosome 11. Ibe murine gcne is composed of 18 exons. 9 of
which have btcn shown to bc altanatively splicccl, and contains two putative uiitidon codons.
Ieading to the synthesis of 52.2 lcDa and 46.7 kDa prodicted gene products. mpectively (Yang et
al.. 1992). Five murine RHAMM isofomis exist (Yang et al.. 1993). Pt kast O- of which
transientiy a p p m a< the ceil nnfaœ whtttas most are found intraccilulady mg. 1). The soif-
form appcais to be glyeosylphosphuidyinositol-iinkcd and insecteci in the outer luRei of the
plasma membrane (unpublished data). RHAMM has two splife sites k w c c n exons 3 and 4
which generate the iniracellular RHAMM variants 2, 3 and 4. Another intracellular isoform,
RHAMMvI. is the most commonly expressed variant in normal murine cells and differs from
RHAMMv3 and RHAMMv4 in that it lacks exon 4 (Hardwick et al.. 1992) (Fig . 1). Other
variants of R H M M have been shown to be released into the tissue culture medium as soluble
proteins of 72. 68. 58 and 52 kDa. but these isofoms have not yet k n well characteri&
(Entwistle et al., 1995).
The e n d e d proteins arc rich in glutamic acid. lysine. glutamine and leucine (Entwistk
et al., 1995) and have nine potentiai sites of N-g1ycosylation. five of which am concentratcd
within a motif near the amino tenninus consisting o f a stretcb of 21 ruidues repeated five tims.
With respect to sccondary structure. RHAMM proteins appmr to be largely a-helicrl. In addition
to aitemative spficing, pod-tmaslationai modificatilioar may &O contn i ta cbe gawdo(t Oc
numemus tissue and species spdc RXAMM procàol.
RHAMM 7 two B(X7)B motifs. wbert B may be e i k aginiae a lysine and X
is any non-acidic Muno acid. ùoth of wbich conmite q d l y to the ability of thir tû
bind hyalumnic acid (Yang et al.. 1994). Positioncd betwœn &O rids Ml41 1 in aie
carboxyl terminus of RHAMM, each of t h e two 10 amino acid domains consists of two rets of
two basic amino si& spaceû sevea ruidues ~ p a h Ciustering of basic amino acids withiii a at
eilher end of the motif enhances hyaimnic acid binding d v i t y . while the occurrence of r i d i c
residues betwten the basic amino acids teduces binding (Yang et al., 1993). In addition to
hyaluronic aci& these dornaias also bind to heparin but not to chondroitin sulphatc or dermaiin
sulfate. A leucine Ppper motif has b e n identifieci in exon 3 of ihc RHAMM gent, which may
mediate its dimerization either with itself or othet binding partners (unpublishd data).
The human RHAMM cDNA. isolated from a breast cDNA library using the murinc
RHAMMv2 as a probe. is 2175 nucleotides in length and encodes a 725 amino acid. 84 kDa
polypeptide (Wong et al.. 1996) (Fig. 2). The overall homology between the overlapping open
reading frames of murine and human RHAMM cDNAs is 85% . However. the hyaluronic r i d
binding motifs (B(x7)E) arc 10040 conservai between human. rat, and mouse sequences (Fig.2).
RHAMM AND CELL MOTIUlV
RHAMM expression has bcen reported to occur transiently at the s u r f e of locomoting
cells. particularly on extcnding lvnellac of fibpoblasts. but is mon o k n pteseat inttpctIlularly
within these same ceiis flurley et al., 1989; Hardwick et ai., 1992; Piluski et ai.. 1994,
Mohapanr et a l , 1996) md within tiima cek (Wang a d. 1998). Oveoupersioa of
RHAMMv4, d t i n g in Uiaused expression of both at the c d d' rnd h the
cytoplasm, has ken shom to indue tnnJformation and CO pmmotc both Mdom a l 1 H t y
and invasion in vivo (HiII et ai.. 1995) and in vitro (Wong et ai., mmuScrip in m o n ) .
RHAMM is a tightly rcgulated protein whose expiession is coordinatcd with the lwmothg
capacity of celis - as ceIl locomotion decreases, extracellular levels of RHAMM p-in decline
(TurIey et al., 1991). Fwthermorc, R H A M M expression is rcgulwd by fadon thai effect a U
locomotion, including wounding (Savani et aL.1993). TGF-p stimulation (Sunuel et al., 1992)
and ras oncogene expression (Hall et al., 1995). However, the mechanisms by which RHAMM
ngulates ccll motility and invasion ut still under investigation. Severai lhes of evidcnce
suggest that hyaluronic acid mediatcd RHAMM signaling in H-ras t r a n s f o d fibroblasts
induces a rapid, transient protein tyrosine kinase phosphorylation, notably of a kinase that has
pnviously been implicated in regulating ce11 motility and focal adhesion turnover - focal
adhesion kinase (p 125 FAK)(Hall et al.. 1994). h has been shown that an anti-RHAMM
antibody. used al a low concentration. is able to elicit proiein tyrosine phosphorylation, and that
tyrosine kinase inhibitors block motility induced either by the anti-RHAMM antibody o r by
hyaiuronic acid (Hail et al., f 994). Furthemore. cetls in \\-hich RHAMM is ablated by antisense
expression exhibit luge. stable focal adhesions (Hall et al.. 1994). and expression of a dominant
negative suppressor mutant of RHAMM (Le. one in which the hyaluronic acid binding domains
an mutated) pnvents the above signding events. =verts ras-induced transfomation. and rcsults
in cells with low motility rates (Hall et al.. 1994). Consistent with thest rtsults, RHAMM
directed motility has ken s h o w to k dependent on src (Hail et al.. 1995). which is a membrane
associated, non-reoeptor pcotein tyrosine kinase involved in cytoskeletal organitation, d l
adhesion and motility. In c-H-ras ûadonned murine fibrosacc~m C C ~ . REïAbM .ad rrr w a e
found to ~prscipit ict rnd <O cofoub to the extending I a d k of Ib~omOfing tells.
Momver, hyaluronic r i d rad RHAMM mediued motiüty in thcse ~u-truisfbœd ails was
blocked by anti-src anti'bodies. and a dominant ncgative sn: w u shown to inhibit RHAMM
mediated motility (HA et J.. 1996). nieJe results suggest that sr^ rts of RHAMM
io signal ce11 motility (HiU et al.. 19%; P i a n g et al.. 1998).
More rccent data dso suggest oüier possible mechaohms by wbich RHAMM may
mediaie ce11 motility. Chang et ai. (1998) bas iacentiy demonrtnted th* RHAMM is transitnîly
organuod in to padosomc-like structures in ceIl processes. which have previcusly becn show to
be involved in cc11 invasion (ïurley et ai.. 1994; Nakahm et ai.. 19%. 1997;Pelh.m et ai.. 1997;
Rabinovitz.1997). Several additional observations suggest thaî both ceil sudacc RHAMM
isoforms and RHAMMv4 are dso involved in regulating extracellular regulated kinase (ERK)
activity (Zhang et al.. 1998). Phosphorylation of ERIC by upstream kinases MEK and raf (Cobbs
et al.. 1995). the latter of which is activated by ras (Daunet al.. 1994). bas been shown to
contribute to ce11 proliferation and motility (Boudewijn et al. 1995; Marshall et al.. 1995).
Hyaluronic acid has also k e n shown to activate ERK activity following response to injury
(Savani et al.. manuscript in preparation). ERK activation by growth factors such as PDGF. as
well as cytoplasmic regdators such as mutant active ras. is mediated by RHAMMv4. which has
shown to form a complex with ERK and MEK. The functional significance of this complex
formation is however not yet clear.
RATlONALE AND HYPOTHESIS FOR THE STUDY
To date, studies of RHAMM function, including its involvement in signai transduction,
have been performed in mammalian ce11 systems. While essential for understanding the
complexity of signaling pathways, such systerns do not offer the advantagcs compubd to simpler
mode1 organisms such as Drosophila mehnogosicr whoa genetics. molecular biology, and
development biology arc nlatively well understood Morcover. the signal transduction pathway
linking ras to ce11 motility has b a n extensively investigaîed in this organism.
Given the importance of RHAMM in ce11 motility and the high evolutionary conservation
of hyaiuronan, we hypothesized that a homologous protein exists in simplet organisrns such as
Drusuphila which may be like marnrndian RHAMM involved in signaling motility. W e also
propose that the role of the putative Drosophila RHAMM homologue in signal transduction will
be more easily studied in this organism, the genome for which may soon to bc compleicly
sequenceà, and for which the phenotype effects of mutations in several thousand genes have
already been describeci. In addition. the well-characterized biology, short life cycle, and relative
ease of handling make Drosophifn an ideal experimeotal mode! for the study of RHAMM
function. To canying out this study. several reagents will be required. some of which we already
possess and others we do not yet possess. Our laboratory has generated antibodies that recognize
RHAMM and cross-react with Drnsophila proteins. Drosopliiln RHAMM cDNA, which will be
required for RT-PCR analysis. howevcr. has no[ yel been obtained. This projecl is designcd 10
fulfill both short and long-term goals as sumrnarized below.
RESEARCH OBJECTIVES
Short Term Goals
Prelirninary studies employ ing Western immunoblotting and immunocytochemical
techniques. using both monoclonal and pol yclonal an tibodics against RHAMM and
including cornpetition shidies. demonstraied the pCGSena of immunortaicrivt spcies of
RHAMM in Drosophih tissues . Southem immunoblot aaadyses have b e n perfonned on Drosophih genomic DNA using
murine RHAMMV4 as a probe. The mlts suggested the presence of a RHAMM
homologue-
RT-PCR analyses have been perfomied on Drosopfilu cDNA using degencrate primes
directeci against conserved sequences of murine RHAMM. These pcÏmen amplifiai som
potential RHAMM homologue DNA sequences. However. southern blot analysis did not
show any cross reactivity with RHAMMv4 cDNA.
Two cDNA libraries (adult and embryonic) from Drosophih have been scrcened using the
RHAMMV4 and RHAMMv2 cDNAs as probes. However. no Positive clones were
detected.
Hornology searches of rnurine RHAMM have been done using BLAST software and
others. No significant homology was found between segments o f rnurine RHAMM and
Drosophiln genes present in the GenBank.
Long Term Goals
In collaboration with Dr. H. Lipshitz in the Department of Genetics at the Hospital for
Sick Children. Drosophih RHAMM cDNA will be used to localize the sequence to a particulv
chromosome in that organism. facilitating the structural characterization of the RHAMM gene.
Studies of RHAMM function in Drosophila. particularly related to its involvement in signal
transduction, will include the analysis of the phenotypic effects of targeted dismption of the
RHAMM gene.
MATERIALS AND METHODS
Western and Dot Blot Analysis
Dot blots and Western analysis were perfonned with monoclonal and pofyclonal
antibodies r a i d against munne RHAMM in order to test the sensitivity and cross mactivity of
this immunoreagents against Drosophila total protein lysatts. for theu powitial use iu
Drosophila cDNA library scrccning. The adult and embryonic nies were frozen in Iiquid
nitrogen followed by their pulverization with a manual pestle. The cells were lysed with ice coid
modified RIPA lysis buffer (25 m M NaCI. ImM EDTA) containing the prokinase inhibitors
leupeptin (1 pdrnl). phtnylrne&ylsulfonyl~uo~de (PMSF, 2 rnMj. pepstatin A (1 Wml).
aprotinin (0.2 pg/ml) and 3.6dicholoroisocoum~n (200 pM) (al1 h m Sigma). Lysetes wen
centrifuged at 13,000 rpm for 20 min at 4OC after incubating on ice for 20 min. Protein
concentrations of the supematants were detennined using the DC protein assay (Bio-Rad). The
required amount of total protein from each lysate were either blotted directly ont0 nitrocellulose
filters (for dot blotting) or loaded ont0 108 SDS gels together with prestained molecular weight
standards (Sigma) (for Western blotting). After transferring proteins from the gels onto
n~trocellulose membranes (Bio-Rad) in buffer contnining 25 itiM Tris-HCI (pH 8.3). 192 mM
glycine, 20% methanol. using electrophoretic transfer cells (Bio-Rad) at 100 V for f hr at 4.c.
additional protein binding sites on the membranes werc blocked with 5% defattcd milk in TBST
(10 mM Tris base (pH 7.4). 150 mM NaCl. with 0.1% Twcen 20. di from Sigma). Doc b i a
membranes were treated similady. The membranes were then ùiarbated with the primary
antibody for RHAMM ovemight at 4'C while shalcing. nie polyclonal antibodics used f a
Western bloaing wcre R3.6 and Ex4, both of which w a e taiscd in nbbits rad ured at 0.16
pg/ml anci 0.2 CLg/ml conœntrations. nspsctivcly, in 1% defatted müi: in TBST. Fadot blottïng,
the monocionai antiôoâics were 3T3-5 rnd 3T3-9. ôoth of WW we~e ured 5.8 p#d
conantrations in 1% defooed milk in TBST. A f k wuhing 3 t i m ~ d witb TBST. tbe membranes
were incubated with horserdish p c m x i ~ j u g a t c d goat anti-&bit IgG (0.2 Wml) for 1
hour at room temperature (RT) and washed with TBST. Blotting was visualized by tk enhanccd
cherniluminescence Western blotting daection systcm (Amersbarn) accordhg to the
manufacturer's instructions. The quantification of optical densitics of the re~ultnnt bands was
performad on the Bio-Rad Mode1 620 V i b Densitometer and analyzcd using the 1-D rnaiyst II
software. The specificity of the antibody binding was confiinaed by pmbing the blots witb R3.6
(O. 16 Wd) and Ex4 (0.20 @ni) pre-incubrted for 2 hr with IWfold exce~s RHAMM furion
pmtein (murine RHAMMv4 cDNA linkcd to giutathionc S-msfe- (GST)-RHAMM fusion
protein. C3 cells (ras-transfonnad murine fibmblasts) were uscd as positive control to detcct
RHAMM. These cells were grown in growth media (GibcoBRL) and were harvested at 5&6û%
confluency. After washing with ice cold PBS. the cells were lysed with modified RIPA lysis
buffer as above.
~mrnunohietochemistry
Formalin-fixcd. paraffincmbeddd adult nies were cut into 4 pm sections and mounted
on polylysinecoaied slicks for assessing RHAMM expression. Following deparaffinkation with
xylene. the scxtions wcn rchydrated in gradcd alcohol (100% ethano1 for 10 min. 95% ethaml
for 5 min, 70% chan015 min. and XI% ethimol for 5 min). Afiu washing two times with PBS.
the endogenous pcroxidue d v i t y wps blockd for 30 min at RT with a 3% H a solution. Tbe
sections werc thcn washed in PBS. a d the MWIS~C&C mtibody bladiag was blochi at 37.C fa
30 min using an aiiquot of 200 pl per slide of 1:10 dilution of maise senua in PBS. Inaibrtion
with an anti-RHAMM m o ~ ~ : l o n a l antîbody (3 Wml of 3T3-5) was pcrformd in PBS at 40C
overnight. PolycIonal antibodies (Ex4 and R3.6) werit used at 4 Wml conceotntions in PBS.
Aftcr 2 washes in 1- anâ lxPBST for 10 min a h . incubation with rabôit-aati-mousc &G
conjugaied to HRP (2 CLg/ml in PBS) was pedornied at RT for 2 hr. Followiag washcs with
PBST and 0.05 M Tris @H 7.2-7.4) for 5 min each the sections were exposcd to chn,mogen
(3.3'-diaminobMzidine (Dm) 5 mgml in 0.05 M Tris (pH 7.2-7.4) for 7-12 mis and tbe cola
change to brown (280 pl PBS + 20 pl DAB) was monitored Counterstaining with hematoxyün
for 1 min was then followd by a wash in running dH20 for 5 min. 'Lbe SCÇtio~ls w m
deyhdrated and mounting for visualization using a microscope
Cloning and DNA Sequencing
Library Screening. I w o separate Drosophila cDNA libraries were screened. One library was
from adult flics (Novagen), and the other was from embryonic cDNA (embryos between 0-24 hr
old) (kindly provided by Dr. H. Lipshitz). Both murine 1.9 kb RHAMMv4 and 900 bp
RHAMMv2 cDNA were used as probes.
Total RNA was extracted from adult nies and embryos using TRIZOL nagent
(GibcoBRL). Approximately 100 mg nies were pulverid in liquid nitrogen with a manual
pestle, rhen treated with 1 ml TREOL reagent. The homogenizcd samples werr incubate. for 5
min at RT to permit the complete dissociation of nuclboprotein complexes. Chloroform (0.2 ml)
was a d d d to the mixtures. which wcrc shakcn vigorousiy by band for 15 s then incubrited for 3
min o n ice. The samplu w a e ccnaifugcd at 1 2 0 g for 15 min r 4OC; the RNA was ex-
in the aqutous pbrre, prscipiwed using 05 mi of isopmpyl dohd. and obuined by
centrifugation at 12.000 g for 10 min at 4.C. Thc pellets wae washd with 1 ml of 70% aicohol.
drid at RT, and dissolved in DEPC-trea!ad water. This total RiUA was d for RT-PCR and
Northern blot anaiysis foUowing its quantification b.sed on its 0% AS a pitiw c01ltrol. the
LR21 (RHAMMv4-Cransfacted) œil lint was usai, the RNA of which was extmztd using
TRIZXlL but with the following modifications: LR21 cells which were &rom on a mcmofaycr in
cornpletc media (Gibco BRL) to 50-6046 confiu«ice wem washed with icecold PBS and
lysed diroctly with TRlUlL without homogenization. 'Ihe cernainder of the m(hd was
followed as describai above.
RT-PCR. RT-PCR of ihe totai RNA w u performod exactly as instmcted by a kit (Clontech).
Bnefly. 1 pg RNA was rtvtrse ~scr ibcd using a 13-mer oligo dT pprimet and 100 uni& of
MMLV reverse transcriptase at 42OC for 60 min. The total 20 pl rcaction volume was diluicd to
100 pl by adding 80 pi of sterile dHIO. 5 fl of the diluted cDNA template was used in each 50
pl PCR reaction dong with thermostable Taq polymerase and degenerate primers designcd
against different regions of murine RHAMM (Table 1). The PCR cycling parameters consisted
of an initial denaturation a< 94OC for 4 min. denaturation at 94OC for I min. annealing at series o f
temperatures and extension for 1 min 72°C. for 40 cycles, and then a final extension of 10 min at
72°C. The PCR products were electrophoresed on an 0.8% agarose gel in IxTBE and denahmd
in 2.5 N NaOH for 20 min at RT with gentie agitation. The products on the gel werc thcn
vansfemd to nitrocellulose in 2 5 N NaOH ovemight and probed with [32p]dCTP labelai 1.9 Kb
W v 4 starting at various strcngencies from low to high.
Sourhem anulysir (m bhs ) Gcnomic DNA wrs extraccd from following species: h u m
mouse, Dosophila, Xclulpus. Z&ra fi&. E.coli. and C.e&g<uu. In guiexal. 1 g of tissue w+i
i mM EDTA (pH 8.0). 0.5% SDS. and 0.1 mglml pocUatse K. nK homagenates w a e inaibataï i j at sooc ovemigbt with UW) pg/mi of ~ ~ u c A. ~heao1-~hlornform extraction SV- fo~owü by
/ p n t k rotation for L hr at RT. ontrihgaîion n 4ûW g fbr 15 min, d exmaio. with pbeool- 8
j chlorofom isoamyl-abho1 was donc at RT for 1 hr with gentle rotation. The DNA was
/ precipitatcd with 3 M Na-acetate and two volumes of iœ-ld cthuiol. mined gatly. rad
spooned out of the mixture. Mtcr washing the DNA twiœ with 70% alcd101 a RT and do-g
it to airdry. it was usp pend ad in lxTE buffer and quantificd on the bais of its obsorbrnce at I
i 260 nm. 'Ihc extractcd genomic DNA was digestcd at 37OC ovemight in 10-20 pg amounts witb ! ! the enzymes EcoRI, B@. and Sad pl 2 unitslpg of DNA. The digests werc then loided ont0 a
0.8% agarose gel and allowcd to run overnight dong with plpsMd conml contlining
RHAMMv4 cDNA at 800 pg dilution. The gel was first denaturd with 0.25 N HCl for exactly
14 min, and then wiih 2.5 N W H for 20 min at RT using gentle agitation, transferrcd using
Hybridization Solution (Siratagene) at 68OC. washed at bah low and high stnngencies. and
final1 y autoradiographed.
RESULTS SUMMARY AND DISCUSSION
Dot Blot and Westem Analyses
A) In Western analysis. murine anti-RHAMM polyclonal antibcxiies (R3.6 and Ex4) nised
against specific amino acids in exon 9 and exon 4 showcd cross reactivity with s e v e d
proteins in Dlosophilo lysattes (Figs. 3A and 4A). Cornpetition studis in which these
antibodiu wcrc prciacubwd with exccss RHAMM hision m i n befat pmbmg the
membranes dut the intemitics of mmy O€ tbe bands wac reduced
after blocking of the antibodies wiai the fiision protein (3B and 4B).
B) Dot blots p c r f d on DrosopNh lysates pmbed witb m o w e l d rntibodies a@st
murine RHAMM showed that .II antibodies displaycd d v i t y wben 1.66 pg of 1-
protein WPI uscû, as show in Figs. 5B. Dccrcasing the Jysatc protein antent to 0.008 pg
resulted in reduccd nrtivity @g. 5B.D). Used as a positive control. RHAMMv4
showed a similar trend to that in Drosophile lysatc. and no apparent cross d v i t y was
seen using mouse IgG as a negative contml (Fig. SA and C).
C) In order to determine the molecular weight of the RHAMM-ükê proteins dcteacd by the
monoclonal antibodies in Drosophiîà lysate. additional Westem analyses werc
performed. Although all antibodiu rcacted with mouse total lysatc (Fig. 6). ody two
(3T3-5 and 3T3-9) reacted with Drosophila total proiein, hvcaling bands betwcen 39
kDa and 52 kDa markers mg. 7A and B). The specificity of the rcactivity of 3T3-S and
3T3-9 with the DrosophiIo proteins were confirmeci by incubating the antibodies with
excess fusion protein, showing that the bands were partialiy blocked (Fig. 7C and D).
O) In summary, b a h monoclonal and polyclonal antibodies cross reacted with potentially
RHAMM-Iike proieins in Drosophila indicaring a band between 52 and 39KDa. and
cornpetition for binding of boih antibodies to lysate components was inhibitcd by
RHAMM fusion protein.
lmmunostaining Analyses
Pdn sections papami from adult f l iu wuc subjectcd to immunohistochernistry with
a monoclonal and two pdycloiul antibodiu. rcvuling immunorcactivity in scverd tissues,
including cye. brain. ovaries, and h m Mouse IgG w u uxd as a negaiive contml in pl- of
the primary antibody (figures wiîi be sboM in the d g ) .
Dot Blot and Southem Blot Analyses
Since the above cesults suggested that a RHAMM-lïke protein is prcseiit in Dmo-
totai genomic DNA of DrosopM& wrr andm fa the preseaa of a RHAMM iikc g a ~ iuhg a
Southem blot assay.
A) Fit. dot blots wcre prfofmcd using genomic DNA h m Drosophila at wocentrations
of 10 pg and 2û pg, and pmM with RHAMMv4 cDNA. This CDNA. as weU as moüsê
genornic DNA and humin genomic DNA werc uscd as positive controls w1g.8). Tbe blot
was washed at stringencies varying from low to high. nit positive signal wrr seen .fw
washing up to 60°C with lxSSC + O. 1% SDS.
B) Southem analyses werc p e r f o d using pnomic DNA f m Drosopirik and otha
specics in order to detcct the prrsence of RHAMM homologues. As soen in Figs.9 and
10. RHAMM-Iike gents are present in Drosophila Xenopus, and C. elegans at low
stringencies up to 5S°C. These results were then confinneci by a xcond set of Southem
analyses (Fig. I I ) using Drosophita and C. elegans genomic DNAs. by which a number
of bands were aetectable in Drosophila and C. elegans DNA ai low stringency washes up
[O 55°C. In siil of the Southern analyses perfornied. RHAMMv4 cDNA and mouse
genomic DNA were uscd as positive controls (Fig. 12). To detst the prercnce of
RHAMM homologues in species closely related to humans. and to optimize conditions
for Southem anaiysis of cross-reactive spccics. eukaryotic zoo bloaing was p c f i o d .
As the results suggcst in Figs. 13 and 14, RHAMM-like genes werc dettctable in rat, dog,
rabbit. as well as in chicken ai diffcrent stringencies. Human RHAMM was dctectablt rit
low stringuicy washes, iduding up to 2xSSC + O. 1% SDS at 55T.
C ) Noahua .nalyses WC= @Ozmdd on totai DrosoprUh RNA to deikt RHAMM merugc.
1 have not yct bzen suocessful with this proadure.
Dl Furthcr RT-PCR milyses wcrc pcrfonncd uring degencntc the rrgi011s
of RHAMM coasaved bttwcm humans and mice @ig.lS). lne PCR ccactioa wis
optimizcd with respect to annding temperature, magnesium conantratiotls, and n u m k
of m o n cycles (Figs.16 and 17). nie many bands amplificd wuc &en probed with
RHAMMv4 cDNA (Fig. 18). No positive bands w e n detectabk
E) cDNA libraries €rom both the adult and embryod wem scrwned using both RHAMMv4
and RHAMMv2 probes. No positive clones were detected.
FUTURE WORK
Short Term Studies
Northem analyses. RT-PCR, and library scncning need to k repcaicd beforc muningful
conclusions can be drawn.
Repeating the immunostaining procedure on the embryonic Drosophila tissue sections to
examine ihe expression levels of the RHAMM-like protein in particular tissues. since the
Western analyses using polyclonal ûntibodies revenled differences in expression. Blocking of
irnmunoreactivity in these sections with RHAMM fusion protein will also be performed.
In the event that library screening is unsuccessful. genomic DNA bands seen on Southem
analyses of Drosophila lysates probed with RHAMMv4 will be eluted from the gel, cloncd
into a suitable vector, and sequenccd-
Long T m Studks
noduction of the Drosophilu knockout rnight enhance wr biowkdge of the role of
RHAMM in siniplcc otgrnisms. lhese studics caild be towuds the shidy of rrr
signai tnnsduction paîh
Study the role of RHAMM homologue in siguüag pathways sinœ thû pthway is wcIi
established in the Drojophila CF.
Fig.2 Homology Cornparison of Human and Murine RHAMM cDNA
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n#uc l w B F # b 1 -
IhmIn 1lMfuowmmrA 11111111111 II-
nGwr 1498 r a C a m a r A T A 4 -
Iluui 1813 m- 1 1 1 1 1 1 1 1 1 l 11 11111 - 1 II
)buie lm l u A w a a t t a t l P l U ~ - . , A
rn 101 mm--- I III II 1111 111111111 lllil 111111111 11111 1 1 1 1 11 111111 II
nPurm 1 7 9 8 O C M O G O ( n ~ ~ - k e r
l b ~ 1073 CIA
hmn 1100 -mçAtWotcrmcmn h I II 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 III 1 I 1 l m
I(ow 1 H B M l l C n o R O M P M I A ~ ~ ~ ~
I I I I I norvr 2023 m A t ~ ~ m o r m i c r - . - - ~ " . - - * - -
Fig.3 Western Blot Analysis of Drosophila Total Protein using Anti-Mouse RHAMM Rabbit Polyclonal Antibody
kDa 1 2 3 4 5 6
Exon4 Antibody
.. .
Exon4 Antibody Preincubated with RHAMMv4 Fusion Protein
Fig. 4 Western Blot Analysis of Drosophila Total Protein using Another Anti-Mouse RHAMM Rabbit Polyclonal Antibody
Fig. 5 Dot Blot Analyses Using Anti-Murine-RHAMM Monoclonal Antibodies
A Concentration of RHAMMV4 fusion protein(pg) B Concentration of Drosophila total protein((ig)
Anti- 3T3-3 m rn rn mm RHAMM Anti-
3T3-5 RHAMM monoclonal monoclonal 3'313-5
antibodies
3T3-6 m m m rn m oniibodies
3T3-7
Fig. 7 Western Blot Analysis of Orosophila Total Protein using Anti-RHAMM MonocIoni Antibody Preincubated with RHAMM Fusion Protein
C3 Dros
3T3-5 333-5 t RHAMMV4 Fusion Protein
B C3 Dros D C3 Dros
3T3-9 + RHAMMV4 Fusion Protein
Fig. 10 Southern Blot, of Genomic DNA of Eukaryotic Species Restricted with EcoR1 and Bg111, Probed with RHAMMv4 cDNA
Low Stringency High Stringency (washed twice with 2xSSCi-û. IZSDS for 2Ornin at 42°C) (washed twice with 2xSSCtû.l%SDS for 2Omin at 55°C)
Lanes: 1 mouse 2 human 3 Dtosophilu 4 Xenopus 5 C. elegans
Fig. 11 Genomic DNA of Eukaryotic Species Restricted with Different Endonucleases
Lane I hHindIII marker Lanes 2-4 Mouse Lanes 5-7 Drosophila Lanes 8- 10 C. elegans Al1 cut with EcoRI, BgliI and Sad respective
Fig. 12 Southern Blot, of Genomic DNA Different Endonucleases,
Low Stringency (washed twice with 2xSSC+O. 1%SDS for 20min at 42OC)
of Eukaryotic Species Restricted with Probed with RHAMMv4
High Stringency (washed twice with 2xSSCM. 1BSDS for 20min at SS°C)
Lanes 1-3 mouse genomic DNA cut Lanes 4-6 Drosophila genomic DNA cut Lanes 7-9 C. elegms genomic DNA cut with EcoR1, BglII, and Sac1 respectively with EcoR1, BglII, and Sac1 respectively with EcoRI, BgM, and S a d nspectively
Fig. 13 EcoR1 -Restricted Genomic DWA of Eukaryotic Species
h HindIII
4 pg genomic DNA Lane 1 . Human Lane 2. Monkey Lane 3. Rat Lane 4. Mouse Lane 5. h g Lane6. Cow Lane 7. Rabbit Lane 8, Chicken Lane 9. Yeast
Fig. 14 Eukaryotic Zoo Blot Probed with RHAMMv4 cDNA
Low Stringency High Stringency (washed twice with LxSSC+O.l%SDS for 20min at 55°C) (washed twice with IxSSCtû. l%SDS for 20min at 60°C)
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
4 pg genomic DNA of : Lane 1. Human Lane 6. Cow Lane 2. Monkey Lane 7. Rabbi t Lane 3, Rat Lane 8. Chicken Lane 4. Mouse Lane 9. Yeast Lane 5. Dog
Fig. 15 Position of Degenerate Primers on Murine RHAMM cDNA and their Homology to Human RHAMM cDNA
Human
Mouse
Human
Mouse
Human
Mouse
Human
Mouse
Human
Mouse
Human
Mouse
Human
5 ' ATAGAGAAAGAAAAGATTGAT ' I
, i / I l / . I I I [~rimer#l] 16 8 ATHGARAARGARAARATTGAT 18 8
S'ATAGAGAAAGAAAAGATTGAT 31 i I I I I I : [~r imer#î]
16 8 ATHGARAARGARAARATMGAT 18 8
5 1 AAAGAAAAGATTGATGAAAAA 3 1
I I I l I I h i / [~rimer#31 17 4 AARGARAARATHGAYGARAAA l g q
5 1 AAACAAAAAATCAAGCATGTT 3 t
I I , I / l / / I [Primertl] 16 6 6 AARCARAARATHAARCAYGTT 16 87
5'CTAAGCTTGGAGTTGATGAA.A 3 1
I I I 1 1 I l i / I I I I / [Primer # 51 9CTAAGCCTGGAATTGATGAAA30
5'AGAAACAAAAGAGAAACAAAGATGAGG 31
/ i l 1 ! 1 ! I l I I I I I H I l I I / [Primer # 61 H= (AtCtT) 3 4 AGAAATAAGAGAGAGACAAAGATGAGG 5 9 Y= (CtT)
R= (A+G) 51 GATGAAAATAGCCAACTCAAATCG 3 ' M= (A+C)
l i l l l ~ ~ l ~ i l i l l I ! I l l l l l / [Primer #71 Mouse 1700 GATGAAAATAGCCAACTCAAATCG 1725
Fig. 16 RT-PCR of Drosophila cDNA using RHAMMv4 Degenerate Primers
Annealing Temperatures ( O C )
Marker 42 44 46 48 50 52 54 56
S'Adapter primer & 3' degenerate primer#l
A
S'Adapter primer & 5'Adapter primer & 3' degenerate pfimem 3' degenerate primedl6
Fig. 18 RT-PCR of Orosophila cDNA using RHAMMv4 Degenerate Primers
Lanes: 1-3 4-5 6-8 9-1 1 12-13 14- 15 15-17 18; 8 0 p g of RHAMMv4 plasmid 19; 80pg of RHAMMv4 plasmid
5ml of sample from A from B from E from D from F fromC fromG
sample annealing temp.*c 52,54,56 respectively 56,70 respectively 56,64,70 56,64,70 5 137 56,6û 57,s 1
Fig. 19 lmmunostaining of Drosophila Eye with Anti-Mouse RHAMM Rabbit Polyclonal Anti body
R3.6 Antibody R3.6 Antibody Preincubated Mouse IgG Control with RHAMM peptide
Fig. 20 lmmunostaining of Drosophila Head with AntCMouse RHAMM Monoclonal Anti body
3T3-5 Antibody H&E Staining
Fig. 22 Southern Blot, of Genomic DNA of Eukaryotic Species Restricted with EcoR1 and Bglll, Probed with RHAMMv4
Low Stringency (washed twice with 2xSSC+O. l%SDS at 42OC)
Lanes: 1 mouse 2 human
5 C elegnns
High Stringency (washed twice with 2xSSCtû. l%SDS at 50°C)
Fig. 23 Southern Blot, of Genomic DNA of Eukaryotic Species Restricted with Different Endonucleases, Probed with RHAMMv4
Low Stringency (washed twice with 2xSSC+O, l%SDS for 20min at 42OC)
k b ~ 1 2 3 4 5 6 7 8 9
Hlgh Stringency (washed twice with ZxSSC-tû. 1 %SDS for 20min at 50°C)
1 2 3 4 5 6 7 8 9
Lanes 1-3 mouse genomic DNA cut Lanes 4-6 Drosophila genomic DNA cut Lanes 7-9 C. elegans genomic DNA cut with EcoRI, BglII, and Sac1 respectively with EcoRI, BgllI, and Sac1 respectivoly with EcoRI, BgIII, and Sac1 respectively
