Breast Cancer Stem cells: NCAB 2/07/06
Implications for Prevention and Therapy
Recent decrease in UK and USAbreast cancer mortality at ages 5069 years
Peto et al. Lancet 355:1822, 2000
Year
Ann
ual D
eath
Rat
e pe
r 10
0,00
0 W
omen
UK
USA
0
15
30
45
60
75
90
105
19501960
19701980
19902000
Breast Cancer Development
Normal Pre-neoplastic Neoplastic Metastatic
GeneticsRisk
AssessmentPrevention Detection Therapy
Local Systemic
CANCER STEM CELL HYPOTHESIS
• Cancers Arise From Tissue Stem Or Progenitor Cells
• Cancers Are “Driven” By Cells With Stem Cell Properties
Characteristics of Stem Cells
• Self Renewal
• Multi-Lineage Differentiation
Development of the Mammary Glandand Mammary Tumors
Common characteristics of normal stem cells and tumor stem cells
Normal stem cell functionality
Ability to self- renew
Anchorage independent survival
and ability to migrate
Long lived/immortalActive antiapoptotic
pathways
Telomerase activity
Resistance to damaging agents
Ability to differentiate
Carcinogenesis
High proliferation potential, tightly controlled
Organogenesis
Adult tissue maintenance and repair
Regeneration of an organ/tissue upon transplantation
Generation of all types of differentiated cells in a tissue
Organogenesis
Uncontrolled proliferation
Tumorigenicity
Tumor heterogeneity
Aberrant organogenesis
More exposed to damaging agents, higher risk of accumulating mutations, corbalanced by
Active DNA repair mechanisms
Higher risk of accumulating mutations
Often defects in DNA repair mechanisms, resulting in mutator phenotype and radio resistance
Genomic instability
Increased transporter actvity and toxic agent exclusion
Metastasis
Chemoresistance
Homing
Common characteristics of normal stem cells and tumor stem cells
Normal stem cell functionality
Ability to self- renewAbility to self- renew
Anchorage independent survival
and ability to migrate
Anchorage independent survival
and ability to migrate
Long lived/immortalActive antiapoptotic
pathways
Telomerase activity
Long lived/immortalActive antiapoptotic
pathways
Telomerase activity
Resistance to damaging agents
Resistance to damaging agents
Ability to differentiate
Ability to differentiate
Carcinogenesis
High proliferation potential, tightly controlled
Organogenesis
Adult tissue maintenance and repair
Regeneration of an organ/tissue upon transplantation
High proliferation potential, tightly controlled
Organogenesis
Adult tissue maintenance and repair
Regeneration of an organ/tissue upon transplantation
Generation of all types of differentiated cells in a tissue
Organogenesis
Uncontrolled proliferation
Tumorigenicity
Uncontrolled proliferation
Tumorigenicity
Tumor heterogeneity
Aberrant organogenesis
Tumor heterogeneity
Aberrant organogenesis
More exposed to damaging agents, higher risk of accumulating mutations, corbalanced by
Active DNA repair mechanisms
Higher risk of accumulating mutations
Often defects in DNA repair mechanisms, resulting in mutator phenotype and radio resistance
Genomic instability
Higher risk of accumulating mutations
Often defects in DNA repair mechanisms, resulting in mutator phenotype and radio resistance
Genomic instability
Increased transporter actvity and toxic agent exclusion
Metastasis
Chemoresistance
Homing
Pathways Involved in Stem CellSelf Renewal and Cancer
• Notch
• Hedgehog
• Bmi-1
• Wnt
Hedgehog Target Gli-2 Promotes Ductal Hyperplasia
CANCER STEM CELL HYPOTHESIS
• Cancers Arise From Tissue Stem Or Progenitor Cells
• Cancers Are “Driven” By Cells With Stem Cell Properties
Models of Tumor Heterogenity
Stochastic model Cancer stem cell model
CSC
CSC
CSC
CSC
Cancer cells are heterogeneous, but most cells can proliferate extensively and form new tumors.
Cancer cells are heterogeneous, and only rare cancer stem cells have the ability to proliferate extensively and form new tumors.
The Isolation of Human Cancer Stem Cells
dissociate
stain withantibodies
Flow-cytometry
CSC
CSC
CSC
Tumorigenicity of Cancer Cell Subsets
Cells / injection 5x105 105 5x104 2x104 104 5x103 103 200
Unsorted (T1) 4/4 4/4 6/6 - 2/6 - 0/6 -B38+CD44+CD24+ - - - 0/5 0/5 0/5 0/5 -B38+CD44+CD24- - - - 5/5 5/5 5/5 5/5 -ESA+CD44+CD24- - - - - - - 8/8 4/4
Unsorted (T2) 4/4 4/4 4/4 - 1/6 - 0/6 -B38+CD44+CD24+ - - - 0/5 0/5 0/5 0/5 -B38+CD44+CD24- - - - 5/5 5/5 5/5 5/5 -
Tumor 1 was derived from a metastatic pleural effusion and Tumor 2 was derived from a primary breast tumor.
CD44+;B38.1+CD24+
CD44+;B38.1+CD24-
Tumor Formation by Human Breast Cancer Cells in Mouse Model
Both Non-Tumorigenic Cancer Cells and Cancer Stem Cellshave a Malignant Appearance, but Only Stem Cells Give
Rise to New Tumors
Cancer stem cellsNon-tumorigenic cellsTumorigenic
Isolatedhumanbreastcancercells
Injectionsites inthe mice
Breast Cancer Stem Cells give rise to Phenotypically Diverse Tumors after Transplantation
Initial tumor CSCs from initial tumor Secondary tumor
Y
X
T1
T2
Hedgehog Activation & Bmi-1 Expression in Cancer Stem Cells
00.00050.001
0.00150.002
0.00250.003
0.00350.004
0.00450.005
PTCH1
Rel
ativ
e m
RN
A ex
pres
sion
(PTC
H1
/ RPL
P0)
Total cellsNon-tumorigenic cellsTumorigenic cells
*
* p < 0.05
00. 0050. 01
0. 0150. 02
0. 0250. 03
0. 0350. 04
0. 0450. 05
Gli1 Gli2
Rel
ativ
e m
RN
A ex
pres
sion
(Glis
/ R
PLP0
)
Total cellsNon-tumorigenic cellsTumorigenic cells
** p < 0.05
00. 020. 040. 060. 080. 1
0. 120. 140. 160. 18
hBmi-1
Rel
ativ
e m
RN
A ex
pres
sion
(hBm
i-1 /
RPL
P0)
Total cellsNon-tumorigenic cellsTumorigenic cells
*
* p < 0.05
Hedgehog signaling pathway
Notch signaling pathway
Bmi-1
Shh, Ihh, Dhh DSL
Cyclopamine GSI
Gli1Gli2
Figure 10
Mammary stem cell self-renewal pathways
Tumorigenic Stem cell
Normal Tumor
Normal Stem cell
Self-renewal Self-renewal
Tumorigenic Stem cellNormal Stem cell
Deregulation
Differentiation Differentiation
Differentiated cells Non-tumorigenic cells
↑PTCH1↑Ihh↑Bmi-1
BMI-1 “Stem-Cell” Signature and Patient Survival
Glinsky et al. JCI 115:1503, 2005
Implications of TSC –Profiling/Diagnosis/Prevention
• Cell of origin may determine molecular profile
• Molecular profiling may miss important TSC genes
• Significance of TSC in metastasis
• Identification of TSC in situ may have diagnostic/prognostic value
• Elimination of mutated stem/progenitor cells important prevention strategy
Normal Development
Stem cell ER-
Self-renewal
Myoepithelial cell
Myoepithelial progenitor
Progenitor cell
?
??
Diff
eren
tiatio
n
ER+ progenitor cell
Paracrine signals
Ductal luminal progenitors
Ductal epithelial cell Alveolar cell
ER+
ER-
Carcinogenesis
Basal
ER-
Cancer stem cell
ER-
ER-
Cancer stem cell
Luminal
B
ER+
ER-
Cancer stem cell
ER-
ER-
Cancer stem cell
ER+
Luminal
A
Cancer stem cell
ER+
Cancer stem cell
ER+
CSC with PARTIAL malignant potential
CSC
TDC
TDC
TDC
TDC
TDC
TDC
No MetastasesCSC=Cancer Stem Cell
TDC=Terminally Differentiated Cell
Cancer Stem Cells: Implications For Metastasis
1o
Tumor CSC with FULL malignant potential
Secondary Oncogenic “Hits” and/or Changes in Microenvironment
Subsequently to other sites
Metastases in months to few years
Dormancy followed by Metastases after many years:
TDC only
NO CSC
The Implications of Human CancerStem Cells (CSCs) for Treatment
Drugs thatkill cancer cellsbut not CSCs
CSCs regenaratetumor
Drugs that killcancer stem cells
Tumor looses itsability to generatenew cells
Tumor degenerates,patient is cured
CSC
CSC
CSC
Tumor regresses
Tumor recurs
Implications of TSCTherapeutics
• Tumor regression inadequate endpoint
– Preclinical models
– Phase II clinical trials
• TSC may be resistant to therapy (apoptosis)
• Effective therapies should target TSC while sparing normal cells
• Genes in TSC self-renewal pathway may provide new therapeutic targets
Evidence for “ Stem Cells”in Human Cancer
• Breast Cancer
• Leukemia
• Multiple Myeloma
• Brain Cancer
• Lung Cancer
• Prostate Cancer
• Melanoma