gevan@cc.ucsf.edu
(415) 514-0759 (lab); (415) 514-0878 (fax)

Box 0502, UCSF; San Francisco, CA 94143-0502

deliveries: 513 Parnassus Ave, HSW-475; San Francisco, CA 94143

Full Biosketch

Jan Dudek, PhD; Daniel Garcia; Melissa Junttila, PhD; Roderik Kortlever, PhD; Yong-Won Kwon, PhD; Carla Martins, PhD; Sharon Reef-Kahan, PhD; Fanya Rostker; Ksenya Shchors, PhD; Nicole Sodir, PhD; Laura Soucek, PhD; Lamorna Swigart, PhD; Jonathan R. Whitfield, PhD; Jin Xu, PhD

Making and Breaking Tumors
Our laboratory is interested in the molecular processes that underlie tumorigenesis, tumor progression and tumor maintenance. Cancers appear very different from the normal tissues from which they are presumably derived, and this has engendered the widely held contemporary view that cancers are the protracted end result of a bewildering complexity of molecular lesions that between them drive the formation of the equally complex neoplastic phenotype. However, appearances can be deceiving. We know that many oncogenes are highly pleiotropic "master" switches that modulate a wide variety of mechanistically diverse processes. Consequently, the apparent complexity of cancers may be instructed by a relatively simple, and hence therapeutically tractable, set of molecular lesions. Our overarching aim is to establish what such molecular lesions might be, what effects they have on specific cell types, alone and in combination, and how critical such lesions are not only to drive tumor formation but also to maintain an established tumor.

Some years ago we noted an unexpected link between the processes that drive cell proliferation and those that promote programmed cell death (apoptosis). We showed that the ubiquitous Myc oncoprotein was a potent trigger of apoptosis in cells deprived of survival factors or subjected to any of a diverse range of insults including DNA damage, interferon and death receptor signaling, hypoxia and nutrient privation. On the basis of such observations, we proposed the now generally accepted notion that the coupling of cell proliferation with cell death represents an innate tumor suppressive mechanism that efficiently restrains the emergence of autonomous clones within the soma. Thus, no cancer can arise without concomitant suppression of cell death. This, in turn, raises some critical questions. First, how does cell death become suppressed during tumorigenesis? Second, besides deregulated cell proliferation and suppressed cell death, what else (if anything) is needed for a cancer to arise? Third, how important is suppression of cell death for the maintenance of established cancers? In particular, might reconstitution of cell death offer an effective and tumor-specific general therapeutic strategy for treating cancer? Much of the work in our laboratory addresses these key questions using a variety of novel experimental systems and technologies.

1. What is the molecular mechanical basis of the coupling between Myc (and other growth deregulating lesions) and the apoptotic machinery?

We are using a combination of biochemical and proteomic approaches to define the changes wrought by Myc activation in the complement of mitochondrial outer membrane proteins. This comprises part of a general strategy to use organelle-specific proteomics to identify effectors of Myc function, focusing initially on the mitochondrial inner and outer membranes, peroxisomes and ER. Thus far, we have identified three candidate mitochondrial outer membrane apoptotic effectors that are rapidly (0.5-2 hrs) induced or modified following Myc activation, a time scale correlating with onset of apoptosis. The ultimate aim is to define the Myc apoptotic molecular modus operandi and compare it with those elicited by other growth deregulating lesions (Rb loss, activated Ras and deregulated E2F1-3). We are also exploring the way in which Myc modulates the balance between pro- and anti-apoptotic effector molecules at the mitochondrion and how to use this knowledge to restore the susceptibility to Myc-dependent apoptosis of tumour cells previously resistant through p53 loss or Bcl-x_L over-expression. Finally, we are dissecting the molecular basis of Myc sensitization to FasL/TNF/TRAIL death receptor signals.

Figure 1 >

2. How important and relevant is Myc-induced apoptosis in the suppression of tumorigenesis in vivo?

To determine the direct outcome of acute Myc activation in different tissues, we have developed a unique switchable and rapidly reversible Myc transgenic system and applied it to several different somatic tissues -- suprabasal skin, liver, GI tract and pancreatic β cells. Activation of Myc in skin leads to immediate hyperplasia with no evident apoptosis. In β cells, Myc-induced proliferation is rapidly overwhelmed by islet apoptosis, resulting in rapid onset of diabetes. In GI tract and liver, Myc activation leads to a mixed phenotype in which both cell expansion and cell death occur simultaneously. Using these models, we have investigated the consequences of suppressing apoptosis by different molecular mechanisms -- over-expression of the Bcl-x_L apoptosis suppressor or loss of the Bax apoptotic effector, (which inactivate the basal apoptotic machinery but leave DNA damage sensing machinery intact) versus loss of ARF or p53 (which uncouple DNA damage from the apoptotic response but leave the basal apoptotic machinery unaffected). Such differing cooperating lesions differentially influence aspects of tumorigenesis, including angiogenesis, invasion and genome instability and speak directly to the highly pleiotropic and variable actions of Myc in differing somatic settings.

3. What role does Myc activation play in the maintenance of cancer?

The reversibility of our switchable Myc models allows us to assess directly the effects of Myc de-activation not only on tumor progression but also on maintenance of established neoplasms. Our studies indicate that de-activation of Myc triggers the rapid regression of tumors in all tissues. Dramatically, such regression is accompanied by collapse of tumor vasculature, strongly suggesting an innate angiogenic activity of Myc. Such observations confirm our earlier hypothesis that Myc directly elicits pro-angiogenic activity in cells and also indicates how growth deregulatory lesions like Myc exert multiple pleiotropic activities necessary for tumour maintenance, making them good potential targets for cancer therapy. More lately, we have combined the rapidity and synchrony of our switchable Myc models with laser capture microdissection and Affymetrix expression microarray technologies to map kinetically the trabnscriptional changes that accompany Myc activation (tumor promotion) and subsequent de-activation (tumor regression) over the course of hours and days. These studies indicate a very restricted set of Myc target genes that are implicated in the maintenance of the neoplastic state.

Figure 2 >

Figure 3 >

4. How and when does the p53 function in damage response and tumor suppression in vivo?

To explore and define directly the role and temporal requirements of p53-dependent tumor suppression in vivo we have used a novel strategy in which the endogenous p53 gene has been replaced with one encoding an ectopically regulatable form of p53. We had earlier shown that a p53ER^TAM chimeric protein, generated by fusing p53 in frame with the 4-hydroxytamoxifen (4-OHT)-dependent oestrogen receptor hormone binding domain, exhibits continuous dependence upon 4-OHT for all measurable aspects of p53 function in vitro. We therefore constructed p53ER^TAM knock-in (KI) mice that can be rapidly and reversibly toggled between p53 null and wild-type status by denial or provision of systemic (or local) 4-OHT. We have demonstrated that such mice are de facto p53 null in the absence of 4-OHT, developing the normal p53 KO spectrum of lymphoid tumours between 2 and 8 moths of age. p53ER^TAM KI mice deprived of 4-OHT exhibit negligible radiation induced thymocyte or GI tract apoptosis, known p53-dependent responses, and are globally resistant to radiotoxic injury. However, systemic administration of 4-OHT as little as 2 hours prior to irradiation recovers complete radio-sensitivity in the thymus.

Using this model, we have for the first time mapped the persistence of the DNA damage response in somatic tissues in vivo and demonstrated that it is short-lived even in the absence of functional p53. This indicates that p53 does not have a significant role in mediating DNA damage repair in vivo. MEFs derived from p53ER^TAM KI spontaneously immortalize in the absence of 4-OHT, rapidly developing dramatic genome instability, aneuploidy and polyploidy and exhibiting complete resistance to Myc-induced apoptosis and Ras-induced replicative senescence, exactly like p53 KO MEFs. In contrast, p53ER^TAM KI MEF maintained in 100 nM 4-OHT resemble p53 wt MEFs. They arrest at passage ~6-8, with normal genomes, senesce upon expression of activated Ras and undergo apoptosis in low serum upon activation of Myc. Using the rapid reversibility of the p53ER^TAM system we have shown that Ras-induced senescence is completely reversible upon de-activation of p53 function, and therefore requires both Ras and p53 to be manifest. In contrast, culture shock-induced senescence of fibroblasts is not reversible upon p53 de-activation, indicating that it is triggered by an irreversible, a persistent and catastrophic event during in vitro propagation. Finally, we have used our model to explore the timing of p53 tumor suppressive action during tumor evolution and have shown that, to all intents and purposes, the DNA damage response is unnecessary for effective suppression of tumorigenesis by p53. This, in turn, has led us to explore the relative impact of episodic p53 restoration on tumour incidence and mouse longevity. Finally, we are exploring the consequences of restoring p53 function in adult MDM2 and MDMX knock-out mice, which otherwise die in early embryogenesis unless p53 is also absent. Such studies will provide new and unique mechanistic insights into the mechanism and requirement for p53 tumour suppression and its role in both normal and neoplastic tissues.

Finally, we have used our model to explore the timing of p53 tumor-suppressive action during tumor evolution and have shown that, to all intents and purposes, the DNA damage response is unnecessary for effective suppression of tumorigenesis by p53. This, in turn, has led us to explore the relative impact of episodic p53 restoration on tumour incidence and mouse longevity. Finally, we are exploring the consequences of restoring p53 function in adult MDM2 and MDMX knockout mice, which otherwise die in early embryogenesis unless p53 is also absent. Such studies will provide new and unique mechanistic insights into the mechanism and requirement for p53 tumour suppression and its role in both normal and neoplastic tissues.

Figure 4 >

5. "Next generation" mouse models of human cancer.

Sporadic, switchable models will obviate many of the limitations and strictures that bedevil existing transgenic and knockout mouse models of cancer and compromise their utility in modelling human neoplasia. To construct such new models that will faithfully recapitulate human disease we have developed a number of novel technologies, including endogenous gene replacement and modification, heterologous repressor binding and "hit and run" tissue-targeting. Our long-term goal is to use these new models as pre-clinical test beds for assaying novel targeted cancer therapies.

Kruidering, M and Evan, GI (2000) Caspase-8 in apoptosis: the beginning of "the end"? IUBMB Life 2000 Aug;50:85-90.

Linsten, T., Ross, A., King, A., Zong, W-X., Rathmell, J., Shiels, H., Ulrich, E., Waymire, K., Mahar, P., Frauwirth, K., Chen, Y., Wei, M., Eng, V., Adelman, D., Simon, M., Ma, A., Golden, J., Evan, G., Korsmeyer, S., MacGregor, G., and Thompson, C. (2001). The combined functions of the pro-apoptotic Bcl-2 family members, Bak and Bax, are essential for the normal development of multiple tissues. Mol Cell 6: 1389-99.

Rudolph, B, Hueber, A-O, and Evan, G (2001). Expression of Mad1 in T cells leads to reduced thymic cellularity and impaired mitogen-induced proliferation. Oncogene20:1164-75

Kruidering, M., Schouten, T., Evan, G. I., and Vreugdenhil, E. (2001). Caspase-mediated cleavage of the Ca2+/calmodulin-dependent protein kinase-like kinase (CaMKLK) facilitates neuronal apoptosis, J Biol Chem 30, 30.

Zornig, M., Hueber, A., Baum, W., and Evan, G. (2001). Apoptosis regulators and their role in tumorigenesis, Biochim Biophys Acta 1551, F1-37.

Evan, G. I., and Vousden, K. H. (2001). Proliferation, cell cycle and apoptosis in cancer, Nature 411, 342-8.

Hunt, A and Evan, G.I. (2001) Apoptosis: Till death us do part. Science 293,1784-5

Pelengaris, S., Khan, M., and Evan, G. (2002). Suppression of Myc-Induced Apoptosis in Cells Exposes Multiple Oncogenic Properties of Myc and Triggers Carcinogenic Progression, Cell 109, 321-334.

Green, D. R., and Evan, G.I. (2002). A matter of life and death. Cancer Cell 1, 19-30.

Soucek, L., and Evan, G. (2002). Myc - Is this the oncogene from Hell?, Cancer Cell 1, 406-8.

You, Z., Saims, D., Chen, S., Zhang, Z., Guttridge, D. C., Guan, K. L., MacDougald, O. A., Brown, A. M., Evan, G., Kitajewski, J., and Wang, C. Y. (2002). Wnt signaling promotes oncogenic transformation by inhibiting c-Myc-induced apoptosis, J Cell Biol 157, 429-40.

Vyas, S., Faucon Biguet, N., Michel, P.P., Monaco, L., Foulkes, N.S., Evan, G. I., Sassone-Corsi, P., and Agid, Y. (2002). Molecular mechanism of neuronal cell death: implications for nuclear factors responding to camp and phorbol esters. Mol. Cell. Neurosci. 21, 1.

Juin, P., Hunt, A., Littlewood, T.D., Griffiths, B., Brown, L., Lowe, S., Evan, G. I. (2002). C-Myc functionally cooperates with the BH3 domain of Bax to induce apoptosis. Mol. Cell. Bio. 22, 6158-69.

Klefstrom, J., Verschuren, E. W. and Evan, G. I. (2002). c-Myc Augments the Apoptotic Activity of Cytosolic Death Receptor Signaling Proteins by Engaging the Mitochondrial Apoptotic Pathway. J Biol Chem,. 277, 43224-43232.

Pelengaris, S., Khan, M. and Evan, G. I. (2002). c-myc: more than just a matter of life and death. Nat Rev Cancer. 2, 764-76.

Verschuren, E. W. Klefstrom, J., Evan, G. I., Jones, N. (2002). The oncogenic potential of Kaposi's sarcoma-associated herpesvirus cyclin is exposed by p53 loss in vitro and in vivo. Cancer Cell. 2, 229-41.

Vyas, S., Biguet, N. F., Michel, P. P., Monaco, L., Foulkes, N. S., Evan, G. I., Sassone-Corsi, P., Agid, Y. (2002). "Molecular mechanisms of neuronal cell death: implications for nuclear factors responding to cAMP and phorbol esters." Mol Cell Neurosci 21: 1-14.

Iaccarino, I., D. Hancock, Evan, G. I., Downward, J. (2003). c-Myc induces cytochrome c release in Rat1 fibroblasts by increasing outer mitochondrial membrane permeability in a Bid-dependent manner. Cell Death Differ 10, 599-608.

Moreau, C., Cartron, P.F., Hunt, A., Meflah, K., Green, D. R., Evan, G., Vallette, F. M., Juin, P. (2003). "Minimal BH3 Peptides Promote Cell Death by Antagonizing Anti-apoptotic Proteins." J Biol Chem 278: 19426-35.

Kanazawa, S., Soucek, L., Evan, G., Okamoto, T., and Peterlin, B. M. (2003). c-Myc recruits P-TEFb for transcription, cellular proliferation and apoptosis. Oncogene 22, 5707-5711.

Khan, M., Pelengaris, S., Cooper, M., Smith, C., Evan, G., and Betteridge, J. (2003). Oxidised lipoproteins may promote inflammation through the selective delay of engulfment but not binding of apoptotic cells by macrophages. Atherosclerosis 171, 21-29.

Murphy, D.J. Brown Swigart, L., Israel, M.A. and Evan, G.I. (2004) Id2 is dispensable for Myc-induced epidermal hyperplasia. Mol Cell Biol. 24: 2083-2090.

Verschuren, E. W., Hodgson, J. G., Gray, J. W., Kogan, S., Jones, N., and Evan, G. I. (2004). The role of p53 in suppression of KSHV cyclin-induced lymphomagenesis. Cancer Res 64, 581-589.

Soucek, L., Nasi, S. Evan, G. I. (2004) Omomyc expression in skin prevents Myc-induced papillomatosis. Cell Death Diff. 11, 1038-45.

Flores, I., Murphy, D.J., Brown Swigart, L., Knies, U. and Evan, G.I. (2004). Exploiting inherent differentiation to counteract c-Myc-driven keratinocyte proliferation in vivo. Oncogene 23, 5923-30.

Vyas, S., Juin, P., Hancock, D. C., Suzuki, Y., Takahashi, R., Triller, A. and Evan, G. I. (2004) Differentiation dependent sensitivity to apoptogenic factors in PC12 cells. J Biol Chem 279, 30983-93.

Knies-Bamforth, U. E., Fox, S. B., Poulsom, R., Evan, G. I. and Harris, A. L. (2004) c-Myc interacts with hypoxia to induce angiogenesis in vivo by a VEGF-dependent mechanism. Cancer Res 64, 6583-70.

Broaddus, V. C., Dansen, T. B., Abayasiriwardana, K. S., Finch, A. J., Swigart, L. B. Hunt, A. E. and Evan, G. I. Bid Mediates Apoptotic Synergy Between TNF-related Apoptosis-inducing Ligand (TRAIL) and DNA Damage. J Biol Chem 280, 12486-93

Lowe, S. W., Cepero, E., and Evan, G. (2004). Intrinsic tumour suppression. Nature 432, 307-315.

Christophorou, M., Martin-Zanca, D., Soucek, L. Lawlor, E.R., Brown-Swigart, L., Vershuren, E. and Evan, G. I. (2005) Temporal dissection of p53 function in vitro and in vivo. Nature GeneticsE-pub May 2005

Dansen, T. B., Whitfield, J., Rostker, F., Brown-Swigart, L., and Evan, G. I. (2006). Specific requirement for Bax, not Bak, in MYC-induced apoptosis and tumor suppression in vivo. J Biol Chem. 281, 10890-95.

Lawlor, E. R., Soucek, L., Brown-Swigart, L., Shchors, K., Bialucha, C. U., and Evan, G. I. (2006). Reversible Kinetic Analysis of Myc Targets In vivo Provides Novel Insights into Myc-Mediated Tumorigenesis. Cancer Res 66. 4591-601.

Jelluma, N., Yang, X., Stokoe, D., Evan, G., Dansen, T., and Haas-Kogan, D. (2006). Glucose withdrawal induces oxidative stress followed by apoptosis in glioblastoma cells but not in normal human astrocytes. Mol Cancer Res 4: 319-330.

Christophorou, M.A., Ringshausen I., Finch A.J., Brown Swigart L. and Evan, G.I. (2006) The pathological p53-mediated response to DNA damage is distinct from p53-mediated tumor suppression. Nature. 443(7108):214-7. Sep 6.

Shchors K, Shchors E, Rostker F, Lawlor ER, Brown-Swigart L, Evan GI. (2006) The Myc-dependent angiogenic switch in tumors is mediated by interleukin 1b. Genes Dev. 20(18):2527-38.

Finch A, Prescott J, Shchors K, Hunt A, Soucek L, Dansen TB, Swigart LB, Evan GI. (2006) Bcl-xL gain of function and p19ARF loss of function cooperate oncogenically with Myc in vivo by distinct mechanisms. Cancer Cell. Aug;10(2):113-20.

Ringshausen I, O'Shea CC, Finch AJ, Swigart LB, Evan GI. (2006) Mdm2 is critically and continuously required to suppress lethal p53 activity in vivo. Ringshausen I, O'Shea CC, Finch AJ, Swigart LB, Evan GI. Cancer Cell. Dec;10(6):501-14.

Martins CP, Brown-Swigart L, Evan GI. (2006) Modeling the Therapeutic Efficacy of p53 Restoration in Tumors. Cell. Dec 29;127(7):1323-34.

Soucek, L., Whitfield, J., Martins, C.P., Finch, A.J., Murphy, D.J., Sodir, N.M., Karnezis, A.N., Swigart, L.B., Nasi, S., and Evan, G.I. (2008). Modelling Myc inhibition as a cancer therapy. Nature. Evan, G.I. (2008). The ever-lengthening arm of p53. Cancer Cell 14, 108-110.

Abayasiriwardana, K.S., Barbone, D., Kim, K.U., Vivo, C., Lee, K.K., Dansen, T.B., Hunt, A.E., Evan, G.I., and Broaddus, V.C. (2007). Malignant mesothelioma cells are rapidly sensitized to TRAIL-induced apoptosis by low-dose anisomycin via Bim. Mol Cancer Ther 6, 2766-2776.

Itahana, K., Mao, H., Jin, A., Itahana, Y., Clegg, H.V., Lindstrom, M.S., Bhat, K.P., Godfrey, V.L., Evan, G.I., and Zhang, Y. (2007). Targeted inactivation of Mdm2 RING finger E3 ubiquitin ligase activity in the mouse reveals mechanistic insights into p53 regulation. Cancer Cell 12, 355-366.

Golipour, A., Myers, D., Seagroves, T., Murphy, D., Evan, G.I., Donoghue, D.J., Moorehead, R.A., and Porter, L.A. (2008). The Spy1/RINGO family represents a novel mechanism regulating mammary growth and tumorigenesis. Cancer Res 68, 3591-3600.

Cano, D.A., Rulifson, I.C., Heiser, P.W., Swigart, L.B., Pelengaris, S., German, M., Evan, G.I., Bluestone, J.A., and Hebrok, M. (2008). Regulated beta-cell regeneration in the adult mouse pancreas. Diabetes 57, 958-966.

Soucek, L., Lawlor, E.R., Soto, D., Shchors, K., Swigart, L.B., and Evan, G.I. (2007). Mast cells are required for angiogenesis and macroscopic expansion of Myc-induced pancreatic islet tumors. Nat Med 13, 1211-1218.

Amaravadi, R.K., Yu, D., Lum, J.J., Bui, T., Christophorou, M.A., Evan, G.I., Thomas-Tikhonenko, A., and Thompson, C.B. (2007). Autophagy inhibition enhances therapy-induced apoptosis in a Myc-induced model of lymphoma. J Clin Invest 117, 326-336.