[CANCER RESEARCH (SUPPL.) 59, 1685s-1692s, April 1, 1999]
Insights from Bel-2 and Mye: Malignancy Involves Abrogation of Apoptosis as well
as Sustained Proliferation 1 S u z a n n e C o r y , 2'3 D a v i d L. V a u x , A n d r e a s S t r a s s e r , A l a n W . H a r r i s , a n d J e r r y M . A d a m s
The Walter and Eliza Hall Institute of Medical Research, PO Royal Melbourne Hospital, Victoria 3050, Australia
It is indeed an enormous honor and pleasure to introduce Drs. Suzanne Cory and Stanley Korsmeyer, this year's winners of the Mott Prize.
I think no one would question the view that their seminal experiments radically changed the way we think about the process of cancer. If we look back about 10 or 15 years, programmed celt death was a very interesting phenomenon, but we had no idea what this meant in terms of cancer, although suggestions were made. It was certainly interesting in terms of development, but we had no idea about the mechanisms involved.
Of course, all this has changed enormously over the last decade, and in terms of cancer particularly, through the seminal contributions of Suzanne Cory and Stan Korsmeyer and their colleagues. Now we know that not only do cancer cells have to escape proliferation controls, they also have to abolish cell death pathways. Not only is this incredibly important for our understanding of the mechanisms underlying cancer, but the way we think about therapy has been radically altered.
And as was said already, it is very exciting and a great coincidence, perhaps, that the Sloan Prize this year is awarded to Bob Horvitz who has used very elegant genetics to dissect cell death pathways in C. elegans. And, of course, what is particularly exciting is the convergence of the studies on bcl-2 in humans and mice with those in C. elegans to show these pathways are conserved. What an exciting combination of studies.
So, now, to introduce Dr. Suzanne Cory. Suzanne has made many seminal contributions over the years, and I would say one thing that has typified her approach has been to use pioneering transgenic experiments to dissect gene interaction in cancer--together with her collaborator over many years, Dr. Jerry Adams, who is here in the audience.
Suzanne got her degree at the University of Melbourne in Australia and then made a very visionary and wise choice in coming to Britain to do her Ph.D. I wasn't going to crack any jokes, just a slight one . . , to do her Ph.D., as she says, in the Department of One Called Francis Crick.
She survived that experience and came out with a very important paper on sequencing transfer RNA which was a breakthrough at the time.
After a productive post-doctoral period in Switzerland, Suzanne then set up a joint laboratory with Jerry Adams in the Walter and Eliza Hall Institute in Melbourne. First, they concentrated on normal B cell development and identified immunoglobulin gene clusters, showed that deletions were important in rearranging those clusters in B cells to bring about the formation of the immunoglobulin genes, and then they moved to pathology and made a very important observation, that in mouse plasmacytomas and Burkitt's lymphoma, the myc gene is deregulated by translocations.
However, they went one step further than that. They actually recreated the myc rearrangements in transgenic animals which then developed lymphomas, proving causality which is a very important thing we all have to do.
The next move that they made was to use transgenic approaches to look at the interaction of different oncogenes and how they cooperate in oncogenesis in mice. Then, in terms of this particular prize, the seminal finding, after the isolation of the bcl-2 oncogene by Stan Korsmeyer and other groups, was the study published in Nature in 1988. Together with David Vaux and Jerry Adams, Suzanne Cory showed that the introduction of bcl2 into B-cells in culture increased their survival. This was, of course, a very, very important observation.
Suzanne then went on to pursue aspects of the biology of bcl-2, showing for example that bcl-2 can cooperate with myc in oncogenesis in transgenic animals, and has continued to study the function of bcl-2 and interacting partners.
Suzanne is now the director of the Walter and Eliza Hall, a very famous, wonderful institute in Melbourne, and she has had many honors over the years, including election to the Royal Society in London in 1992, and foreign membership of the National Academy of Sciences in 1997. She has also won the Burnet's Medal and shared the 1998 Australia Prize of the Australian Academy of Sciences.
Nicholas D. Hastie Medical Research Council Human Genetics Unit Western General Hospital Edinburgh, United Kingdom
Abstract
The chromosome translocations typifying Burkitt's lymphoma and follicular lymphoma deregulate very different oncogenes, myc and bcl-2.
Received 11/11/98; accepted 1/27/98. 1 Presented at the "General Motors Cancer Research Foundation Twentieth Annual Sci-
entific Conference: Developmental Biology and Cancer," June 9-10, 1998, Bethesda, MD. Most of the research reviewed here was suppolted by the National Health and Medical Research Council of Australia (NHMRC Reg. Key 977171), the National Cancer Institute in the United States (CA43540), and the Howard Hughes Medical Institute (75193-531101).
2 To whom requests for reprints should be addressed. 3 Co-recipient of the Mott Prize along with Stanley Korsmeyer, whose article can be
found on pages 1693s-1700s of this supplement.
Transgenic mouse models have illuminated how each contributes to lym- phomagenesis. Constitutive myc expression provokes sustained cell pro- liferation and retards differentiation. However, the resulting expansion in cell number is self-limiting, because the cells remain dependent on cyto- kines and undergo apoptosis when these become limiting. In contrast, bcl-2 is the prototype of a new class of oncogene that enhances cell survival but does not promote proliferation. Coexpression of these genes leads to the rapid transformation of lymphocytes, probably because each can counter an antioncogenic aspect of the other. Several close homologues of Bcl-2 also enhance cell survival and are thus potential oncogenes; each is essential for maintenance of particular major organs. More distant Bcl-2 relatives instead promote apoptosis and can be regarded as tumor sup-
pressors. For many but not all apoptic signals, the balance between these competing activities determines cell survival. Learning how to adjust the apoptotic threshold in cancer cells should promote development of more effective therapeutic strategies.
100
Many leukemias and lymphomas are hallmarked by specific karyo- typic abnormalities, the first recognized being the Philadelphia chro- mosome of chronic myeloid leukemia (1), produced by a reciprocal translocation between chromosomes 9 and 22 (2). Such abnormalities have been the rosetta stone tbr identifying causative oncogenic mu- tations.
By modeling in transgenic mice the translocations specific to Bur- kitt 's lymphoma and follicular lymphoma, we showed that these B-lymphoid malignancies stem from fundamentally different types of oncogenic mutation. The Burkitt's mutation, deregulation of c-myc, results in loss of control of cell division, whereas that in follicular lymphoma, deregulation of bcl-2, results in decreased susceptibility to cell death. Importantly, these mutations can act in concert, driving the inexorable and rapid development of lymphoma. The lessons learned are relevant to diverse neoplasms.
myc: An Oncogene That Provokes Loss o f G r o w t h Control
Burkitt's lymphoma is an aggressive malignancy common in chil- dren in equatorial Africa and Papua New Guinea. The majority of these tumors exhibit a translocation involving chromosomes 8 and 14; its murine counterpart is the t(12; 15) tbund in most of the plasmacy- tomas arising in BALB/c mice injected with mineral oil (3). As reviewed previously (4), several laboratories, including ours, inde- pendently established in the early 1980s that both these translocations result from a reciprocal recombination event involving c-myc and the immunoglobulin heavy chain (Igh) locus (5-11). As Ohno et al. (12) first hypothesized, these interchromosomal recombination events ap- pear to be an accidental by-product of the intrachromosomal rear- rangement of Igh genes obligatory in normal B-lymphoid ontogeny.
The critical outcome of the reciprocal translocation (13) is consti- tutive expression of c-myc, enforced by its subjugation to an Igh enhancer (14). The c-myc gene product is a basic/helix-loop-helix transcription factor that regulates several genes that maintain cells in cycle. The oncogenic potential of myc had already been flagged by retrovirus studies. Indeed, its name derives from avian m_yelocytoma- tosis virus, the genome of which bears a mutated form of the gene, and retroviral activation of the cellular gene is frequent in chicken B lymphomas (15) and in murine T lymphomas (16).
Despite the tight association of the myc translocation with Burkitt' s lymphoma and murine plasmacytoma, the case for an etiological role remained circumstantial. To obtain direct proof, we generated mice bearing a transgene comprised of myc linked to the intronic Igh enhancer (E/x), to mimic the translocation and enforce constitutive Myc production throughout the B-lymphoid compartment. The E/x- myc transgene proved a potent, heritable lymphomagenic agent; within the first year of life, all of the mice acquired disseminated lymphoma accompanied by leukemia (17, 18). Similar findings were made by Leder's laboratory (19). The oncogenic potential of myc was not confined to a single differentiation stage, because both pre-B and B lymphomas developed, and some E/x-myc mice treated with mineral oil succumbed to plasmacytoma (20). These experiments established beyond doubt that the deregulation of myc contributes to the devel- opment of most Burkitt's lymphomas and plasmacytomas. A minor subclass of such tumors bearing variant translocations involving im- munoglobulin light chain loci probably also activate myc albeit from a greater distance (4, 21).
Close analysis of the E/x-myc mouse model was enlightening. Although newborn mice were healthy and devoid of transplantable tumor cells, they showed clear evidence of a preneoplastic condition: a marked increase in pre-B cells, most of which were in cycle, accompanied by a reduction in mature B cells (22). Thus, enforced myc expression had promoted proliferation and retarded differentia- tion. The lymphomas that subsequently arose stochastically were monoclonal and highly transplantable. Furthermore, the kinetics of their onset suggested that the myc-driven pre-B cells became malig- nant at a frequency of about 1 per 10 ~~ cell divisions (18). The strong implication was that tumor onset required one or two somatic muta- tions as well as constitutive myc expression. Genetic background also played a significant role; tumor onset on a BALB/c background was considerably faster than on a C57BL/6 background (Fig. 1). Such background effects in transgenic models should prove valuable in the coming search for genes modifying susceptibility to human cancer.
The myc mice provided a fertile testing ground for identifying synergistic oncogenic mutations. Some 10% of the lymphomas har- bored mutated ras (N- and K-ras) genes (23). The inferred myc-ras synergy, noted earlier in other cell types (24, 25), was proven by showing that mice bearing both an E/x-N-ras and an E/x-myc trans- gene succumbed to lymphomas much faster than those bearing either alone (20). In an alternative approach for identifying synergistic mutations, neonatal E/x-myc mice were infected with Moloney murine leukemia virus, which can activate and thereby tag a cellular proto- oncogene. The proviral insertion sites associated with accelerated lymphomagenesis included pim-1, which encodes a ser/thr kinase, and a novel gene dubbed bmi-1 (26, 27), which encodes a transcriptional repressor of certain homeotic genes. How these proteins collaborate with Myc is still unclear, but it is intriguing to speculate that Bmi-1, for example, might repress certain homeobox genes necessary for differentiation.
Finally, it is noteworthy that lymphocytes from E/x-myc mice remained dependent on cytokines and in fact died faster than those
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I N S I G H T S F R O M B C L - 2 A N D M Y C
1 I I I I 0 10 20 30 40
Age (wk) Fig. 1. Rate of Etx-myc transgene-induced lymphomagenesis varies with genetic
Fig. 2. Bcl-2 enhances cell survival. A, interleukin 3 (IL-3)-dependent FDC-P1 myeloid cells and a derivative line expressing bcI-2 retrovirus were cultured for 3 days with and without 1L-3. In the presence of IL-3, both lines proliferated and remained viable (e.g., left panel). In the absence of IL-3, the parental cells died rapidly (center panel). Those expressing the bcl-2 retrovirus survived well in the absence of IL-3 (right panel) but withdrew from cycle, as evidenced by their smaller size. B, viability of independent clones of parental FDC-PI myeloid cells and LyH7 pro-B cells (open symbols) and bcl-2 virus-infected derivatives (closed symbols) after 3 days in the absence of IL-3.
from normal mice when deprived of cytokines (28). The clear impli- cation was that cells forced to cycle by myc die rapidly when cyto- kines become limiting, thus accounting for the plateau in lymphocyte numbers observed in vivo and in vitro. Askew et al. (29) and Evan et
al. (30) subsequently established that myc promotes programmed cell death (apoptosis) under adverse growth conditions.
bcl-2: A n O n c o g e n e That Regulates Cell D e a t h
Following the paradigm established by Burkitt's lymphoma, the karyo- typic abnormalities in many leukemias and lymphomas have been cloned as aberrant rearrangements of immunoglobulin or T cell receptor genes (31). Among these was the 14;18 translocation found in the relatively indolent but common follicular lymphoma. Studies by Tsujimoto et al.
(32), by Bakhshi et al. (33), and by Cleary et al. (34) revealed that the gene brought into the Igh locus was a novel one, and it was dubbed bcl-2
(B-cell lymphoma gene 2). As in the myc translocation, the bcl-2 coding region remained intact, and the critical outcome was constitutive produc- tion at high levels of Bcl-2 in the affected B cell and its clonal progeny. The Bcl-2 protein was found to be associated with cytoplasmic mem-
branes (35) [more specifically, the endoplasmic reticulum and the outer membranes of mitochondria and the nucleus (36)], but apart from a hydrophobic COOH terminus, thought to be a membrane anchor, its amino acid sequence revealed no recognizable motifs.
The function of Bcl-2 remained a mystery, until Vaux et al. (37) introduced the gene into interleukin 3-dependent cell lines. Most unexpectedly, withdrawal of the cytokine revealed that the depend- ency had now been altered (Fig. 2). Although the cells still could not multiply in the absence of interleukin 3, they survived for many days and proliferated again when resupplied with cytokine. This now- classic experiment demonstrated that cell survival is regulated sepa- rately from proliferation and that the function of Bcl-2 is to inhibit apoptosis. Thus, Bcl-2 became the prototype of a new class of onco- gene, one that exerts its action by enhancing cell survival rather than stimulating cell division.
Studies of bcl-2 transgenic mice developed by us and by Korsmey- er's group (38-41) confirmed and extended these observations. The B-lymphoid compartment was expanded 4- to 5-fold, but in contrast to the myc mice, the cells were not in cycle. B and T lymphocytes
Fig. 3. Synergy between Bcl-2 and Myc. A, Bcl-2 expression facilitates survival. B-lymphoid cells from the bone marrow of young healthy bcl-2, myc, and bcl-2/myc mice and nontransgenic litter- mates were cultured in conventional culture me- dium (i.e., lacking exogenous cytokines such as IL-7), and viability was measured by trypan blue exclusion; bars, SD. B, Bcl-2 enhances lym- phomagenesis induced by Myc. Cumulative mortal- ity from lymphoma in mice carrying both El~-bcl-2 and El~-myc transgenes versus that in mice carrying each alone.
Fig. 4. A, p53 deficiency accelerates lymphoma onset in Eix-myc mice. Hererozygous p53 +/- mice were crossed with EIx-myc mice, and lymphoma onset was determined in progeny bearing both mu- tations versus each alone. B, PCR analysis reveals that lymphomagenesis in p53+/- animals is ac- companied by loss of the wild-type p53 allele.
INSIGHTS FROM BCL-2 AND MYC
A B
53 +1- myc +
40[-" ~ "" /
/ I
4 8 12 16 20
A g e (weeks)
lymphomas con I[--q
- mut -wt
expressing the bcl-2 transgene proved remarkably robust in the face of diverse cytotoxic insults. The normally fragile CD4+CD8 + thymo- cytes, for example, were recalcitrant to treatment with ionizing radi- ation, glucocorticoids, phorbol ester, or calcium ionophore.
As predicted, the bcl-2 transgene proved oncogenic, albeit less so than myc. The incidence of B-lymphoid tumors was higher in the bcl-2
mice than their nontransgenic littermates, although the penetrance was low (10-15% over 12 months), and the latency was long (42, 43). Thus, the transgenic models paralleled the human diseases; Myc produced an aggressive malignancy, whereas Bcl-2 produced an in- dolent one.
Another oncogenic mutation that can enhance survival of certain cell types is loss or inactivation of the tumor suppressor p53. Such cells normally undergo apoptosis when p53 levels increase in re- sponse to DNA damage (44). The protection against DNA damage proffered by Bcl-2, however, is broader than that conferred by loss of p53; Bcl-2 inhibits apoptosis of both resting and cycling T cells, whereas the absence of p53 protects only the quiescent cells (45). High levels of Bcl-2 in tumor cells may therefore be a graver imped- iment to genotoxic cancer therapy than loss of p53.
Dangerous Liaisons
Many of the tumors arising in bcl-2 mice exhibited a rearranged myc gene, implicating collaboration between myc and bcl-2 (42, 43). That synergy had first been inferred from the demonstration that infection of bone marrow cells from pretumorous myc mice with a bcl-2 retrovirus yielded immortal tumorigenic pre-B cell lines (37). Striking evidence emerged from crosses of myc and bcl-2 mice (46). Young bitransgenic offspring had copious pre-B cells, with blood leukocyte levels 50-100-fold higher than normal and even 25-fold higher than littermates bearing only the myc transgene. Importantly, however, these cycling bcl-2-myc pre-B cells were not fully malig- nant; despite their greatly enhanced survival in the absence of cyto- kines (Fig. 3A), they were not transplantable. Thus, even this potent oncogene combination does not fully transform lymphoid cells. Nev- ertheless, every bcl-2-myc mouse went on to develop a transplantable lymphoma before 7 weeks of age (Fig. 3B). Unexpectedly, each tumor had the phenotype of a primitive progenitor cell and retained both B-lymphoid and macrophage differentiation potential (46, 47). Pre- sumably, additional mutation(s) were involved, but it remains unclear
Fig. 5. Pathways to cell death in C. elegans and mammals (see text).
C. elegans
"2
/
Mammals
dexamethasone ~ ] staurosporine Fas ligand DNA damage \~//cytokine deprivation
intracellular L L..V_ I- ~ T F plasma C~~95 membrane r ,-,2~- I / I-B-- ~ membrane I~ Fas/APO-1
why a rare stem cell is so susceptible to transformation by the myc/bcl-2 combination.
Curiously, despite this clear potential for synergy, no bcl-2 trans- locations were detected in lymphomas arising spontaneously in mvc mice (23). However, inactivation of p53 was detected in some 10- 20% of early passage lines derived from the E~-myc tumors 4 and in a significant proportion of Burkitt's lymphomas (48, 49). In accord with that finding, introduction of the Etx-myc transgene into a het- erozygous p53 +/- background by breeding led to very early lymphoma (Fig. 4A). Remarkably, almost every tumor had lost the wild-type p53 allele (e.g., Fig. 4B), as also observed by Hsu et al. (50). Clearly, loss of p53, like gain of Bcl-2, synergizes very effectively with constitu- tive Myc expression to transform lymphocytes.
These studies indicate that the combination of an oncogenic muta- tion that suppresses the intrinsic cell death program with one that overrides the physiological brakes on cell division is a potent recipe for cancer. Most likely, mutations that enhance cell survival counter the "safety net" of apoptosis, which normally swings into action when cells are induced to divide under adverse or restrictive conditions (29, 30).
The Expanding Bcl-2 Family
A great deal is now known about Bcl-2, although its biochemical mode of action remains controversial (51-54). Bcl-2 is in fact but one of a complex family of proteins regulating apoptosis (Fig. 5). The 15 or so members fall into three subfamilies. Some, like Bcl-2, enhance cell survival, and each of these is a potential oncogene. Other rather similar proteins, such as the prototype Bax, discovered by Oltvai et al. (55), counter this survival function and even promote apoptosis when expressed at high concentrations. A third, more recently recognized group comprises proteins largely unrelated to each other or to Bcl-2, except for a short (9-16 amino acids) central domain known as BH3. These "BH3-only" proteins are potent inducers of apoptosis. Indeed, Bim, a novel BH3-only protein we identified recently, is so potent that stable lines cannot be isolated from cells transduced with bim cDNA unless they also overexpress bcl-2 (56). The pro- and antiapoptotic cousins can heterodimerize and seemingly titrate one another's func- tion, suggesting that their relative concentration acts as a rheostat for the suicide program (55). Heterodimerization involves insertion of the BH3 domain of the prodeath proteins into a pocket created by three conserved domains of the prosurvival proteins, as shown by Fesick and co-workers (57, 58). The ability of BH3-dolnain and Bax family members to counter Bcl-2 action suggests that the proapoptotic pro- teins may act as tumor suppressors, and indeed, many human gastro- intestinal cancers and some leukemias have been shown recently to contain nmtations of bax (59).
A Bel-2 Homolog Essential for Spermatogenesis
The two closest homologs of Bcl-2 are Bcl-x L (60) and Bcl-w, discovered in our laboratory (61). All three protect cells from the same array of cytotoxic agents and do so equally well, when expressed at a comparable concentration (62). Nevertheless, gene disruption has revealed tissue-specific requirements. Whereas Bcl-2 is essential for the maintenance of the mature lymphoid system (63) and Bcl-x L for the development of erythroid and neuronal cells (64, 65), Bcl-w is necessary for spermatogenesis (66, 67). In bcl-w-null mice, testicular development and prepubertal spermatogenesis are largely unaffected, but adult seminiferous tubules are disorganized, Sertoli cells and germ cells of all types are reduced in number, and there are no mature sperm. Most likely a particular prosurvival gene is required in certain
4 Our unpubl ished results.
tissues because it is the sole guardian expressed there. However, it also remains possible that individual inhibitors block certain cell death pathways more effectively than others.
The Bel-2 Family Controls Many but not All Roads to Death
How does the Bcl-2 family control apoptosis? The engine driving cellular suicide is a family of proteases homologous to Ced-3, the product of one of three genes (ced-3, ced-4, and egl-1) shown by Horvitz and co-workers (68, 69) to be essential for developmental cell deaths in Caenorhabditis elegans (Fig. 5). These proteases, now called caspases, cleave their targets after aspartate residues. To protect the cell, they are synthesized as almost inactive zymogens. Activation requires cleavage at sites that are themselves caspase consensus sites; therefore, apoptosis entails a caspase cascade (70).
In C. elegans, the ced-9 gene inhibits programmed cell death by antagonizing the action of ced-4 and ced-3 (71). Importantly, Vaux et al. (72) and Hengartner and Horvitz (73) found that human bcl-2 can inhibit cell death in the nematode, a striking demonstration of the evolutionary conservation of the machinery of apoptosis (74). How Bcl-2 and Ced-9 function remains uncertain. In keeping with the localization of Bcl-2, some evidence links its function to the perme- ability or integrity of organelles, particularly the mitochondrion (75). An alternative view, aligned more obviously with the C. elegans genetics, favors a more direct role for the prosurvival molecules. Some recent evidence has suggested that the prosurvival proteins may function by binding to and inhibiting Ced-4-1ike adaptor molecules needed to facilitate aggregation and autocatalysis of caspases (re- viewed in Refs. 54 and 76). The conserved NH2-terminal BH4 region of Bcl-2 homologs, required for their prosurvival activity, may be critical for any such interaction (77). In mammalian cells, proapop- totic cousins such as Bax and Bim may act by binding to Bcl-2 homologues, thereby allowing Apaf-1 homologues to induce death via caspase-9 (Fig. 5). Other putative adaptors may similarly activate other caspases. Likewise, in nematodes, the BH3 domain protein Egl-1 interacts with Ced-9, probably releasing the adaptor Ced-4 to activate Ced-3 (69). The very divergent sequences of the BH3-domain subfamily may hint that each responds to a distinct death/survival signal, one to a damaged cytoskeleton, for example, and another to damaged DNA. Some may also preferentially target subsets of the death repressors.
Bcl-2 is not a panacea for mammalian cell death. In several cell lines and activated normal T cells (78) and in cells targeted by cytotoxic T cells (40, 62, 79), it is ineffectual against the signal induced by "death receptors" such as CD95 (Fas/APO-1) and other members of the tumor necrosis factor receptor family. Ligand-induced aggregation of these receptors leads, via the adaptor protein FADD/ Mortl, to activation of caspase-8 (80; Fig. 5). This pathway appears to be independent of Apaf-1 and caspase-9 (81, 82). Additional mammalian death pathways undoubtedly remain to be discovered, because neither gain of Bcl-2 nor inactivation of FADD/Mortl pre- vents, for example, the culling of autoreactive thymocytes (40, 79, 83).
A Restraint on Entry into Cell Cycle
Bcl-2 and its homologs not only control cell survival but can also modulate the cell cycle. An early hint of this connection was the quies- cence of Bcl-2-expressing cells that survived cytokine withdrawal (37), and their reentry into cycle on restimulation was subsequently found to be retarded (84, 85). Furthermore, thymocyte turnover is slowed in bcl-2 transgenic mice, as is the mitogenic response of their lymphocytes (86- 89). Bcl-2 also hastens withdrawal from cycle (90). Importantly, the inhibitory effect of Bcl-2 on cell cycle entry is genetically separable from its survival function; the former but not the latter is ablated by mutation
Fig. 6. Complementarity of Bcl-2 and Myc function (see text).
of a tyrosine residue near the NHa-terminal BH4 domain (91) or by a deletion in the adjacent nonconserved loop (92). Inhibition of cell cycle entry might involve a protein that can bind to this region, such as the phosphatase calcineurin (93). Whatever the mechanism, the cell cycle inhibitory effect may have evolved to reduce the oncogenic impact of Bcl-2. It seems pertinent that progressed follicular lymphomas often display missense mutations in the relevant NH2-terminal region (94).
Concluding Remarks
The long-observed multistage development of malignancy is now seen to be due to the sequential acquisition of the diverse genetic a l t e ra t ions n e e d e d to s u b v e r t con t ro l s on cr i t ica l c e l l u l a r p roce s se s .
D e c i p h e r i n g the m o l e c u l a r bas is o f k a r y o t y p i c a b n o r m a l i t i e s has
r e v e a l e d k e y m u t a t i o n s u n d e r l y i n g m a n y n e o p l a s m s , and t r ansgen ic
m o d e l s ( 9 5 - 9 7 ) h a v e p r o v i d e d v a l u a b l e ins igh t in to h o w spec i f i c
m u t a t i o n s th rus t cel ls f r o m n o r m a l c y t o w a r d m a l i g n a n c y . S e p a r a t e
m u t a t i o n s m a y be n e e d e d to p r e v e n t t e rmina l d i f f e r en t i a t i on , to a l l ow
m o r e a u t o n o m o u s g r o w t h , and to e x t e n d c lona l l i fe span (98).
M o s t no t ab ly , d e l i n e a t i o n o f ro l e o f the b c l - 2 t r a n s l o c a t i o n in
fo l l i cu l a r l y m p h o m a has r e s u l t e d in a f u n d a m e n t a l l y a l t e red v i e w o f
m a l i g n a n t t r a n s f o r m a t i o n . T h e r ea l i z a t i on tha t b c l - 2 exer t s its o n c o -
g e n i c e f f e c t t h r o u g h s u p p r e s s i o n o f cel l dea th (37) r a the r than e n h a n c -
ing ce l l p ro l i f e r a t i on o r b l o c k i n g ce l l d i f f e r e n t i a t i o n has g rea t i m p o r t
f o r a p p r o a c h e s to t he rapy .
T h e d r ama t i c s y n e r g y b e t w e e n m y c and b c l - 2 d e m o n s t r a t e d fo r
l y m p h o m a (46) and m a m m a r y c a r c i n o m a (99) m a y r e f l ec t the ab i l i ty
o f e a c h gene to c o u n t e r an a n t i o n c o g e n i c i m p u l s e o f the o ther . U n d e r
l im i t i ng g r o w t h cond i t i ons , M y c o v e r e x p r e s s i o n el ic i ts an a p o p t o t i c
r e s p o n s e as we l l as p ro l i f e r a t i on , w h e r e a s B c l - 2 e n c o u r a g e s ce l l c y c l e
ex i t as we l l as su rv iva l (Fig. 6). S y n e r g i s t i c m u t a t i o n s tha t r e m o v e
res t ra in t s on ce l l c y c l i n g and fo i l p a t h w a y s to apop tos i s m a y be
r e q u i r e d fo r the d e v e l o p m e n t o f m a n y , i f no t all, n e o p l a s m s .
A c k n o w l e d g m e n t s
We thank our many colleagues for their participation and insights.
R e f e r e n c e s
1. Nowell, P. C., and Hungerford, D. A. A minute chromosome in human chronic granulocytic leukemia. Science (Washington DC), 132: 1497, 1960.
2. Rowley, J. D. A new consistent chromosomal abnormality in chronic myelogenous leukaemia identified by quinacrine fluorescence and Giemsa staining. Nature (Lond.), 243: 290-293, 1973.
3. Klein, G. The role of gene dosage and genetic transpositions in carcinogenesis. Nature (Lond.), 294: 313-318, 1981.
4. Cory, S. Activation of cellular oncogenes in hemopoietic cells by chromosome translocation. Adv. Cancer Res., 47: 189-234, 1986.
5. Adams, J. M., Gerondakis, S., Webb, E., Mitchell, J., Bernard, O., and Cory, S. Transcriptionally active DNA region that rearranges frequently in murine lymphoid tumors. Proc. Natl. Acad. Sci. USA, 79: 6966-6970, 1982.
6. Adams, J. M., Gerondakis, S., Webb, E., Corcoran, L. M., and Cory, S. Cellular myc
1690s
oncogenc is altered by chromosome translocation to an immunoglobulin locus in murine plasmacytomas and is rearranged similarly in human Burkitt lymphomas. Proc. Natl. Acad. Sci. USA, 80: 1982-1986, 1983.
7. Harris, L. J., Lang, R. B., and Marcu, K. B. Non-immunoglobulin-associated DNA rearrangements in mouse plasmacytomas. Proc. Natl. Acad. Sci. USA, 79: 4175- 4179, 1982.
8. Calame, K., Kim, S., Lalley, P., Hill, R., Davis, M., and Hood, L. Molecular cloning of translocations involving chromosome 15 and the immunoglobulin C a gene from chromosome 12 in two murine plasmacytomas. Proc. Natl. Acad. Sci. USA, 79: 6994-6998, 1982.
9. Taub, R., Kirsch, I., Morton, C, Lenoir, G., Swan, D., Tronick, S., Aaronson, S., and Leder, P. Translocation of the c-rnyc gene into the immunoglobulin heavy chain locus in human Burkitt lymphoma and murine plasmacytoma cells. Proc. Natl. Acad. Sci. USA, 79: 7837-7841, 1982.
10. Shen-Ong, G. L., Keath, E. J., Piccoli, S. P., and Cole, M. D. Novel myc oncogene RNA from abortive immunoglobulin-gene recombination in mouse plasmacytomas. Cell, 31: 443-452, 1982.
11. Dalla-Favera, R., Martinotti, S., Gallo, R. C., Erikson, J., and Croce, C. M. Trans- location and rearrangements of the c-myc oncogene locus in human undifferentiated B-cell lymphomas. Science (Washington DC), 219: 963-967, 1983.
12. Ohno, S., Babonits, M., Wiener, F., Spira, J., Klein, G., and Potter, M. Nonrandom chromosome changes involving the Ig gene-carrying chromosomes 12 and 6 in pristane-induced mouse plasmacytomas. Cell, 18: 1001-1007, 1979.
13. Gerondakis, S., Cory, S., and Adams, J. M. Translocation of the myc cellular oncogene to the immunoglobulin heavy chain locus in murine plasmacytomas is an imprecise reciprocal exchange. Cell, 36: 973-982, 1984.
14. Bernard, O., Cory, S., Gerondakis, S., Webb, E., and Adams, J. M. Sequence of the murine and human cellular myc oncogenes and two modes of myc transcription resulting from chromosome translocation in B lymphoid tumours. EMBO J., 2: 2375-2383, 1983.
15. Hayward, W. S., Neel, B. G., and Astrin, S. M. Activation of a cellular onc gene by promoter insertion in ALV-induced lymphoid leukosis. Nature (Lond.), 290: 475- 480, 1981.
16. Corcoran, L. M., Adams, J. M., Dunn, A. R., and Cory, S. Murine T lymphomas in which the cellular myc oncogene has been activated by retroviral insertion. Cell, 37: 113-122, 1984.
17. Adams, J. M., Harris, A. W., Pinkert, C. A., Corcoran, L. M., Alexander, W. S., Cory, S., Palmiter, R. D., and Brinster, R. L. The c-myc oncogene driven by immunoglob- ulin enhancers induces lymphoid malignancy in transgenic mice. Nature (Lond.), 318: 533-538, 1985.
18. Harris, A. W., Pinkert, C. A., Crawford, M., Langdon, W. Y., Brinster, R. L., and Adams, J. M. The Eix-myc transgenic mouse: a model for high-incidence spontaneous lymphoma and leukemia of early B cells. J. Exp. Med., 167: 353-371, 1988.
19. Schmidt, E. V., Pattengale, P. K., Weir, L., and Leder, P. Transgenic mice bearing the c-myc gene activated by an immunoglobulin enhancer: a pre-B cell lymphoma model. Proc. Natl. Acad. Sci. USA, 85: 6047-6051, 1988.
20. Harris, A. W., Langdon, W. Y., Alexander, W. S., Hariharan, I. K., Rosenbaum, H., Vaux, D., Webb, E., Bernard, O., Crawford, M., Abud, H., Adams, J. M., and Cory, S. Transgenic mouse models for hematopoietic tumorigenesis. Curt. Top. Microbiol. Immunol., 141: 82-93, 1988.
21. Webb, E., Adams, J. M., and Cory, S. Variant (6;15) translocation in a murine plasmacytoma occurs near an immunoglobulin ~ gene but far from the myc oncogene. Nature (Lond.), 312: 777-779, 1984.
22. Langdon, W. Y., Harris, A. W., Cory, S., and Adams, J. M. The c-myc oncogene perturbs B lymphocyte development in EIx-myc transgenic mice. Cell, 47." 11-18, 1986.
23. Alexander, W. S., Bernard, O., Cory, S., and Adams, J. M. Lymphomagenesis in Elx-myc transgenic mice can involve ras mutations. Oncogene, 4: 575-581, 1989.
24. Land, H., ParMa, L. F., and Weinberg, R. A. Tumorigenic conversion of primary embryo fibroblasts requires at least two cooperating oncogenes. Nature (Lond.), 304: 596-602, 1983.
25. Sinn, E., Muller, P., Pattengale, I., Tepler, R., Wallace, P., and Leder, F. Coexpression of MMTV/v-Ha-ras and MMTV/c-myc genes in transgenic mice: synergistic action of oncogenes in vivo. Cell, 49: 465-475, 1987.
26. Haupt, Y., Alexander, W. S., Barri, G., Klinken, S. P., and Adams, J. M. Novel zinc finger gene implicated as myc collaborator by retrovirally accelerated lymphomagen- esis in Eix-myc transgenic mice. Cell, 65: 753-763, 1991.
27. van Lohuizen, M., Verbeek, S., Scheijen, B., Wientjens, E., van der Gulden, H., and Berns, A. identification of cooperating oncogenes in Eix-myc transgenic mice by provirus tagging. Cell, 65: 737-752, 1991.
28. Langdon, W. Y., Harris, A. W., and Cory, S. Growth of EIx-myc transgenie B- lymphoid cells in vitro and their evolution toward autonomy. Oncogene Res., 3: 271-279, 1988.
29. Askew, D. S., Ashmun, R. A., Simmons, B. C., and Cleveland, J. L. Constitutive c-myc expression in an IL-3-dependent myeloid cell line suppresses cell cycle arrest and accelerates apoptosis. Oncogene, 6: 1915-1922, 1991.
30. Evan, G. I., Wyllie, A. H., Gilbert, C. S., Littlewood, T. D., Land, H., Brooks, M., Waters, C. M., Penn, L. Z., and Hancock, D. C. Induction of apoptosis in fibroblasts by c-myc protein. Cell, 69:119-128, 1992.
31. Rabbitts, T. H. Chromosomal translocations in human cancer. Nature (Lond.), 372: 143-149, 1994.
32. Tsujimoto, Y., Finger, L. R., Yunis, J., Nowell, P. C., and Croce, C. M. Cloning of the chromosome breakpoint of neoplastic B cells with the t(14;18) chromosome translocation. Science (Washington DC), 226: 1097-1099, 1984.
33. Bakhshi, A., Jensen, J. P., Goldman, P., Wright, J. J., McBride, O. W., Epstein, A. L., and Korsmeyer, S. J. Cloning the chromosomal breakpoint of t(14;18) human lym-
phomas: clustering around Ju on chromosome 14 and near a transcriptional unit on 18. Cell, 41: 899-906, 1985.
34. Cleary, M. L., Smith, S. D., and Sklar, J. Cloning and structural analysis of cDNAs 63. for bcl-2 and a hybrid bcl-2/immunoglobulin transcript resulting from the t(14;18) translocation. Cell, 47: 19-28, 1986.
35. Tsujimoto, Y., Ikegaki, N., and Croce, C. M. Characterization of the protein product 64. of bcl-2, the gene involved in human follicular lymphoma. Oncogene, 2: 3-7, 1987.
36. Monaghan, P., Robertson, D., Amos, T. A. S., Dyer, M. J. S., Mason, D. Y., and Greaves, M. F. Ultrastructural localization of BCL-2 protein. J. Histochem. Cyto- chem., 40: 1819-1825, 1992. 65.
37. Vaux, D. L., Cory, S., and Adams, J. M. bcl-2 gene promotes haemopoietic cell survival and cooperates with c-myc to immortalize pre-B cells. Nature (Lond.), 335: 440-442, 1988. 66.
38. McDonnell, T. J., Deane, N., Platt, F. M., Nufiez, G., Jaeger, U., McKearn, J. P., and Korsmeyer, S. J. bcl-2-immunoglobulin transgenic mice demonstrate extended B cell survival and follicular lymphoproliferation. Cell, 57: 79-88, 1989. 67.
39. Strasser, A., Whittingham, S., Vaux, D. L., Bath, M. L., Adams, J. M., Cory, S., and Harris, A. W. Enforced BCL2 expression in B-lymphoid ceils prolongs antibody responses and elicits autoimmune disease. Proc. Natl. Acad. Sci. USA, 88: 8661- 8665, 1991. 68.
40. Strasser, A., Harris, A. W., and Cory, S. Bcl-2 transgene inhibits T celt death and perturbs thymic self-censorship. Cell, 67: 889-899, 1991. 69.
41. Sentman, C. L., Shutter, J. R., Hockenbery, D., Kanagawa, O., and Korsmeyer, S. J. bcl-2 inhibits multiple forms of apoptosis but not negative selection in thymocytes. Cell, 67: 879-888, 1991. 70.
42. McDonnell, T. J., and Korsmeyer, S. J. Progression from lymphoid hyperplasia to high-grade malignant lymphoma in mice transgenic for the t(14; 18). Nature (Lond.), 71. 349: 254-256, 1991.
43. Strasser, A., Harris, A. W., and Cory, S. Etx-bcl-2 transgene facilitates spontaneous 72. transformation of early pre-B and immunoglobulin-secreting cells but not T cells. Oncogene, 8: 1-9, 1993.
44. Yonish-Rouach, E., Resnitzky, D., Lotem, J., Sachs, L., Kimchi, A., and Oren, M. 73. Wild-type p53 induces apoptosis of myeloid leukaemic cells that is inhibited by interleukin-6. Nature (Lond.), 352: 345-347, 1991.
45. Strasser, A., Harris, A. W., Jacks, T., and Cory, S. DNA damage can induce apoptosis 74. in proliferating lymphoid cells via p53-independent mechanisms inhibitable by Bcl-2. Cell, 79: 329-339, 1994. 75.
46. Strasser, A., Harris, A. W., Bath, M. L., and Cory, S. Novel primitive lymphoid tumours induced in transgenic mice by cooperation between myc and. bcI-2. Nature 76. (Lond.), 348: 331-333, 1990. 77.
47. Strasser, A., Elefanty, A. G., Harris, A. W., and Cory, S. Progenitor tumours from Etx-bcl-2-myc transgenic mice have lymphomyeloid differentiation potential and reveal developmental differences in cell survival. EMBO J., 15: 3823-3834, 1996. 78.
48. Wiman, K. G., Magnusson, K. P., Ramqvist, T., and Klein, G. Mutant p53 detected in a majority of Burkitt lymphoma cell lines by monoclonal antibody PAb240. Oncogene, 6: 1633-1639, 1991. 79.
49. Gaidano, G., Ballerini, P., Gong, J. Z., lnghirami, G., Neri, A., Newcomb, E. W., Magrath, 1. T., Knowles, D. M., and Dalla-Favera, R. p53 mutations in human lymphoid malignancies: association with Burkitt lymphoma and chronic lymphocytic 80. leukemia. Proc. Natl. Acad. Sci. USA, 88: 5413-5417, 1991.
50. Hsu, B., Marin, M. C., E1-Naggar, A. K., Stephens, L. C., Brisbay, S., and McDon- 81. nell, T. J. Evidence that c-myc mediated apoptosis does not require wild-type p53 during lymphomagenesis. Oncogene, 11: 175-179, 1995.
51. Cory, S. Regulation of lymphocyte survival by the BCL-2 gene family. Annu. Rev. 82. Immunol., 13: 513-543, 1995.
52. Vaux, D. L., and Strasser, A. The molecular biology of apoptosis. Proc. Natl. Acad. Sci. USA, 93: 2239-2244, 1996.
53. Strasser, A., Huang, D. C. S., and Vaux, D. L. The role of the bct-2/ced-9 gene family 83. in cancer and general implications of defects in cell death control for tumourigenesis and resistance to chemotherapy. Biochim. Biophys. Acta, 1333: F151-F178, 1997.
54. Adams, J. M., and Cory, S. The Bcl-2 protein family: arbiters of cell survival. Science 84. (Washington DC), 281: 1322-1326, 1998.
55. Oltval, Z. N., Milliman, C. L., and Korsmeyer, S. J. Bcl-2 heterodimerizes in vivo with a conserved homolog, Bax, that accelerates programmed cell death. Cell, 74: 85. 609-619, 1993.
56. O'Connor, L., Strasser, A., O'Reilly, L. A., Hansmann, G., Adams, J. M., Cory, S., and Huang, D. C. S. Bim-a novel member of the Bcl-2 family that promotes 86. apoptosis. EMBO J., 17: 384-395, 1998.
57. Muchmore, S. W., Sattler, M., Liang, H., Meadows, R. P., Harlan, J. E., Yoon, H. S., Nettesheim, D., Chang, B. S., Thompson, C. B., Wong, S-L., Ng, S-C., and Fesik, 87. S. W. X-ray and NMR structure of human Bcl-x L, an inhibitor of programmed cell death. Nature (Lond.), 381: 335-341, 1996.
58. Sattler, M., Liang, H., Nettesheim, D., Meadows, R. P., Harlan, J. E., Eberstadt, M., 88. Yoon, H. S., Shuker, S. B., Chang, B. S., Minn, A. J., Thompson, C. B., and Fesik, S. W. Structure of Bcl-xL-Bak peptide complex: recognition between regulators of apoptosis. Science (Washington DC), 275: 983-986, 1997. 89.
59. Rampino, N., Yamamoto, H., Ionov, Y., Li, Y., Sawai, H., Reed, J. C., and Perucho, M. Somatic frameshift mutations in the bax gene in colon cancers of the microsatellite mutator phenotype. Science (Washington DC), 275: 967-969, 1997. 90.
60. Boise, L. H., Gonzalez-Garcia, M., Postema, C. E., Ding, L., Lindsten, T., Turka, L. A., Mao, X., Nufiez, G., and Thompson, C. B. bcl-x, a bcl-2-related gene that thnctions as a dominant regulator of apoptotic cell death. Cell, 74: 597-608, 1993. 91.
61. Gibson, L., Holmgreen, S., Huang, D. C. S., Bernard, O., Copeland, N. G., Jenkins, N. A., Sutherland, G. R., Baker, E., Adams, J. M., and Cory, S. bcl-w, a novel member of the bcl-2 family, promotes cell survival. Oncogene, 13: 665-675, 1996. 92.
62. Huang, D. C. S., Cory, S., and Strasser, A. Bcl-2, BcI-X L and adenovirus protein
1691s
EIBI9kD are functionally equivalent in their ability to inhibit cell death. Oncogene, 14: 405-414, 1997. Veis, D. J., Sorenson, C. M., Shutter, J. R., and Korsmeyer, S. J. Bcl-2-deficient mice demonstrate fulminant lymphoid apoptosis, polycystic kidneys, and hypopigmented hair. Cell, 75: 229-240, 1993. Motoyama, N., Wang, F. P., Roth, K. A., Sawa, H., Nakayama, K., Nakayama, K., Negishi, I., Senju, S., Zhang, Q., Fujii, S., and Loh, D. Y. Massive cell death of immature hematopoietic cells and neurons in Bcl-x deficient mice. Science (Wash- ington DC), 267: 1506-1510, 1995. Ma, A., Pena, J. C., Chang, B., Margosian, E., Davidson, L., Alt, F. W., and Thompson, C. B. Bclx regulates the survival of double-positive thymoeytes. Proc. Natl. Acad. Sci. USA, 92: 4763-4767, 1995. Ross, A. J., Waymire, K. G., Moss, J. E., Parlow, A. F., Skinner, M. K., Russell, L. D., and MacGregor, G. R. Testicular degeneration in Bcl-w-deficient mice. Nat. Genet., 18: 251-256, 1998. Print, C. G., Loveland, K. L., Gibson, L., Meehan, T., Stylianou, A., Wreford, N., de Kretser, D., Metcalf, D., KOntgen, F., Adams, J. A., and Cory, S. Apoptosis regulator Bcl-w is essential for spermatogenesis but appears otherwise redundant. Proc. Natl. Acad. Sci. USA, 95: 12424-12431, 1998. Ellis, H. M., and Horvitz, H. R. Genetic control of programmed cell death in the nematode C. eIegans. Cell, 44: 817-829, 1986. Conradt, B., and Horvitz, H. R. The C. elegans protein EGL-l is required for programmed cell death and interacts with the Bcl-2-1ike protein CED-9. Cell, 93: 519-529, 1998. Thornberry, N. A., and Lazebnik, Y. Caspases. Enemies within. Science (Washington DC), 281: 1312-1316, 1998. Hengartner, M. O., Ellis, R. E., and Horvitz, H. R. Caenorhabditis elegans gene ced-9 protects cells from programmed cell death. Nature (Lond.), 356: 494-499, 1992. Vanx, D. L., Weissman, I. L., and Kim, S. K. Prevention of programmed cell death in Caenorhabditis elegans by human bcl-2. Science (Washington DC), 258: 1955- 1957, 1992. Hengartner, M. O., and Horvitz, H. R. C. elegans cell survival gene ced-9 encodes a functional homolog of the mammalian proto-oncogene bcl-2. Cell, 76: 665-676, 1994. Vaux, D. L., Haecker, G., and Strasser, A. An evolutionary perspective on apoptosis. Cell, 76: 777-779, 1994. Green, D. R., and Reed, J. C. Mitochondria and apoptosis. Science (Washington DC), 281: 1309-1311, 1998. Vaux, D. L. CED-4-The third horseman of apoptosis. Cell, 90: 389-390, 1997. Huang, D. C. S., Adams, J. M., and Cory, S. The conserved N-terminal BH4 domain of Bcl-2 homologues is essential for inhibition of apoptosis and interaction with CED-4. EMBO J., 17: 1029-1039, 1998. Strasser, A., Harris, A. W., Huang, D. C. S., Krammer, P. H., and Cory, S. Bcl-2 and Fas/APO-1 regulate distinct pathways to lymphocyte apoptosis. EMBO J., 14: 6136- 6147, 1995. Vaux, D. L., Aguila, H. L., and Weissman, 1. L. Bcl-2 prevents death of factor- deprived cells but fails to prevent apoptosis in targets of cell mediated killing. Int. Immunol., 4: 821-824, 1992. Ashkenazi, A., and Dixit, V. M. Death receptors: signaling and modulation. Science (Washington DC), 281: 1305-1308, 1998. Yoshida, H., Kong, Y-Y., Yoshida, R., Elia, A. J., Hakem, A., Hakem, R., Penninger, J. M., and Mak, T. W. Apafl is required for mitochondrial pathways of apoptosis and brain development. Cell, 94: 739-750, 1998. Hakem, R., Hakem, A., Duncan, G. S., Henderson, J. T., Woo, M., Soengas, M. S., Elia, A., de la Pompa, J. L., Kagi, D., Khoo, W., Potter, J., Yoshida, R., Kanfman, S. A., and Lowe, S. W. Differential requirement for caspase 9 in apoptotic pathways in vivo. Cell, 94: 339-352, 1998. Newton, K., Harris, A. W., Bath, M. L., Smith, K. G. C., and Strasser, A. A dominant interfering mutant of FADD/Mortl enhances deletion of autoreactive thymocytes and inhibits proliferation of mature T lymphocytes. EMBO J., 17: 706-718, 1998. Marvel, J., Perkins, G. R., Lopez-Rivas, A., and Collins, M. K. L. Growth factor starvation of bcl-2 overexpressing murine bone marrow cells induced refractoriness to IL-3 stimulation of proliferation. Oncogene, 9: 1117-1122, 1994. O'Reilly, L., Huang, D. C. S., and Strasser, A. The cell death inhibitor Bcl-2 and its homologues influence control of cell cycle entry. EMBO J., 15: 6979-6990, 1996. Linette, G. P., Li, Y., Roth, K., and Korsmeyer, S. J. Cross talk between cell death and cell cycle progression: BCL-2 regulates NFAT-mediated activation. Proc. Natl. Acad. Sci. USA, 93: 9545-9552, 1996. Mazel, S., Burtrum, D., and Petrie, H. T. Regulation of cell division cycle progression by bcl-2 expression: a potential mechanism for inhibition of programmed cell death. J. Exp. Meal., 183: 2219-2226, 1996. O'Reilly, L. A., Harris, A. W., Tarlinton, D. M., Corcoran, L. M., and Strasser, A. Expression of a bcl-2 transgene reduces proliferation and slows turnover of devel- oping B lymphocytes in vivo. J. lmmunol., 159: 2301-2311, 1997. O'Reilly, L. A., Harris, A. W., and Strasser, A. BcL2 transgene expression promotes survival and reduces proliferation of CD3 CD4-CD8 T cell progenitors. Int. Immunol., 9: 1291-1301, 1997. Vairo, G., Innes, K. M., and Adams, J. M. Bcl-2 has a cell cycle inhibitory function separable from its enhancement of cell survival. Oncogene, 13: 1511- 1519, 1996. Huang, D. C. S., O'Reilly, L. A., Strasser, A., and Cory, S. The anti-apoptosis function of Bcl-2 can be genetically separated from its inhibitory effect on cell cycle entry. EMBO J., 16: 4628-4638, 1997. Uhlmann, E. J., D'Sa-Eipper, C., Subramanian, T., Wagner, A. J., Hay, N., and Chinnadurai, G. Deletion of a nonconserved region of Bcl-2 confers a novel gain of
function: suppression of apoptosis with concomitant cell proliferation. Cancer Res., 56: 2506-2509, 1996.
93. Shibasaki, F., Kondo, E., Akagi, T., and McKeon, F. Suppression of signalling through transcription factor NF-AT by interactions between calcineurin and Bcl-2. Nature (Lond.), 386: 728-731, 1997.
94. Matolcsy, A., Casali, P., Warnke, R. A., and Knowles, D. M. Morphologic transfor- marion of follicular lymphoma is associated with somatic mutation of the translocated Bcl-2 gene. Blood, 88: 3937-3944, 1996.
95. Cory, S., and Adams, J. M. Transgenic mice and oncogenesis. Annu. Rev. Immunol., 6: 25-48, 1988.
96. Adams, J. M., and Cory, S. Transgenic models of tumor development. Science (Washington DC), 254:1161-1167, 1991.
97. Adams, J. M., and Cory, S. Transgenic models for haemopoietic malignancies. Biochim. Biophys. Acta, 1072: 9-31, 1991.
98. Metz, T., Harris, A. W., and Adams, J. M. Absence of p53 allows direct immortalization of hematopoietic cells by the myc and raf oncogenes. Cell, 82: 29-36, 1995.
99. Jager, R., Herzer, U., Schenkel, J., and Weiher, H. Overexpression of Bcl-2 inhibits alveolar cell apoptosis during involution and accelerates c-myc-induced tumorigenesis of the mammary gland in transgenic mice. Oncogene, 15: 1787-1795, 1997.
1999;59:1685s-1692s. Cancer Res Suzanne Cory, David L. Vaux, Andreas Strasser, et al. of Apoptosis as well as Sustained ProliferationInsights from Bcl-2 and Myc: Malignancy Involves Abrogation
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