Apply to Graduate School | Library | Jobs & Volunteers | Visitor Information | Department Index | News      
Department of Cancer Biology

 

 

George Kulik Ph.D.

Assistant Professor of Cancer Biology

 

Education

D.V.M., Ukrainian Agricultural Academy, Ukraine, Veterinary Medicine 1986 

Ph.D., Inst. Experimental Pathology, Ukraine, 1991

Research Interests

Research in my laboratory is focused on signal transduction mechanisms that protect prostate cancer cells from apoptosis.  This information is necessary to design more effective therapies for advanced prostate cancer and other therapy-resistant cancers.
Text Box: Fig. 1. Signal transduction network that regulates BAD phosphorylation.

Recently, we have identified BAD as a convergence point of several anti-apoptotic pathways downstream from PI3K/Akt, EGFR, and GPCRs (Fig. 1).  Detailed analysis of these signaling pathways revealed a complex network of remarkable redundancy that connects signals from the tumor microenvironment with BAD phosphorylation (ref 6-7).  

These findings have formed a foundation for several research projects described below.

1. Emotional stress and prostate cancer. 

Almost two millennia ago, Galen observed that emotional stress may lead to cancer.  However, results of modern-day epidemiological studies that address the connections between stress and cancer remain controversial.  This controversy is largely due to the lack of mechanistic understanding of how stress could influence tumor development and therapy resistance.  

While analyzing the anti-apoptotic network in prostate cancer, we have found that epinephrine (at concentrations observed after chronic emotional stress) protects prostate cancer cells from apoptosis via the PKA/BAD mechanism (8).  Recent experiments show that injections of epinephrine or emotional stress counteract the anti-tumor effects of PI3K inhibitors on prostate cancer xenografts in mice (fig. 2).  Based on these observations, we hypothesize that emotional stress activates anti-apoptotic signaling in prostate cancer cells and, as a result, contributes to the progression of prostate cancer and resistance of advanced prostate cancer to therapies.  If this hypothesis is confirmed, it will provide a mechanistic explanation for the connection between emotional stress and cancer. 

The project will be developed in the following directions: a) prostate cancer xenografts and a transgenic mouse model of prostate cancer will be used to test the role of emotional stress and depression in cancer development and therapeutic sensitivity; b) the signaling pathways activated by stress hormones and their role in apoptosis regulation will be analyzed; and c) stress hormone levels in prostate cancer patients and their responses to therapies will be assessed.   

Text Box: Fig. 2. Stress and epinephrine negate apoptotic effects of LY294002 in vivo in xenograft tumors. A) Stress and epinephrine negate luminescence reduction by LY294002. Mouse tumors were injected with 60 mg/kg LY or vehicle (DMSO, n=3) in vivo. LY-injected mice were divided into three groups. First group was left untreated (LY, n=4), second group was subjected to immobilization stress (LY+stress, n=2) and third group injected with 30 ng/kg epinephrine (LY+Epi n=3). Tumor luminescence was followed for 72 hours and change in luminescence was plotted as a fraction of luminescence measured prior to injections. Error bars show SE. B) Representative luminescent images imposed over black and white images of mice injected with either DMSO or LY294002. Arrow indicate injection site. C) LY294002 injections induce apoptosis in tumor xenografts. Sections of tumors injected with either LY294002 or DMSO prepared 72 h post injection. Arrows indicate apoptotic “dust”. D) LY294002 injections inhibit Akt phosphorylation in vivo. Lysates from xenografts injected with 60 mg/kg LY294002 or DMSO were probed with phosphospecific antibodies that recognize pS474 and pT308 of Akt. E) Stress and epinephrine injections induce CREB phosphorylation in xenograft tumors in vivo. Lysates of xenografts from calm mice, mice subjected to stress, or injected with 180 ng/kg epinephrine.

2) The role of BAD phosphorylation in prostate tumor development in vivo. 

Use of a prostate cancer xenograft model and genetically modified mice are proposed in these experiments.  For experiments with xenograft tumors, we generated C42Luc prostate cancer cells that express firefly luciferase and either wild-type BAD or BAD2SA with mutated phosphorylation sites.  Growth of C42Luc xenografts was followed in live mice by noninvasive optical imaging (fig. 2 A and B).  To test the role of BAD phosphorylation in mouse models of prostate cancer, genetically modified mice in which endogenous BAD is replaced by mutant BAD3SA (BAD3SA knock-in mice) will be bred with mice that develop prostate cancer due to prostate-restricted expression of PTENp-/- or c-myc.  If expression of phosphorylation-deficient BAD prevents prostate cancer development, then signaling pathways that control BAD are plausible targets for anti-cancer therapy.  Subsequent efforts will be focused on identification of kinases that control BAD in prostate cancer cells and testing effects of inhibition of these kinases on tumor growth.

3) Prostate tumor-targeted kinase inhibitors. 

This interdisciplinary project provides a unique training opportunity by including all stages of drug discovery: computer modeling of drug-enzyme interaction (with biophysicist Dr. Freddie Salsbury), chemical synthesis of candidate drugs (with chemist Dr. Mark Welker); in vitro and in vivo testing of synthesized drugs in mouse models of prostate cancer (with Dr. George Kulik).  The goal is to synthesize prostate tumor-specific inhibitors of signaling pathways that control BAD phosphorylation and apoptosis.  Prostate tumor specificity will be achieved by a) generating an inactive pro-drug activated by prostate tumor-secreted protease (PSA); and b) targeting pro-drug to prostate tumors by prostate-specific antibodies.  Computer modeling will be used to analyze interactions between activated pro-drugs and target kinases; candidate pro-drugs selected based on this modeling will be synthesized and tested in vitro and in vivo using luminescent xenografts models of prostate cancer.

Recent publications

1)  George Kulik, Anke Klippel, and Michael J. Weber.  (1997) Antiapoptotic signalling by the Insulin-like growth factor receptor, Phosphatidylinositol 3-kinase, and Akt.  Molecular and Cellular Biology, 17: 1595-1606.
2)  George Kulik and Michael J. Weber.  (1998) Akt-dependent and independent survival signalling pathways utilized by IGF-I.  Molecular and Cellular Biology, 18:6711-6718.
Jonatan P. Carson, George Kulik and Michael J. Weber.  (1999) Anti-apoptotic signaling in LNCaP prostate cancer cells: a survival signaling pathway independent of PI3 kinase and Akt/PKB. Cancer Res. 59: 1449-1453.
3)  George Kulik, Jonathan P. Carson, Tomas Vomastek, Kevin Overman, Barry D. Gooch, Srinivasa Srinivasula, Emad Alnemri, Gabriel Nunez and Michael J. Weber. (2001) TNF-a induces BID cleavage and bypasses antiapoptotic signals in prostate cancer LNCaP cells.  Cancer Res. 61: 2713-2719.
4)  Jonathan P. Carson, Marcelina Behnam, Jennifer Sutton, Chunying Du, Xiaodong Wang, Donald Hunt, Michael J. Weber and George Kulik. (2002) Smac is required for cytochrome c-induced apoptosis in prostate cancer LNCaP cells.  Cancer Res. 62: 18-23.
5)  Konduru S. R. Sastry, Adrienne Joy Smith, Yelena Karpova, Sandeep Robert Datta, and George Kulik.  (2006) Diverse anti-apoptotic signaling pathways activated by VIP, EGF and PI3K in prostate cancer cells converge on BAD.  J Biol Chem. 281(30):20891-901.
6)  Konduru S. R. Sastry, Yelena Karpova, and George Kulik.  (2006) Epidermal Growth Factor Protects Prostate Cancer Cells from Apoptosis by Inducing BAD Phosphorylation via Redundant Signaling Pathways.  J Biol. Chem. 281(37):27367-77.
7)  Sastry KS, Karpova Y, Prokopovich S, Smith AJ, Essau B, Gersappe A, Carson JP, Weber MJ, Register TC, Chen YQ, Penn RB, Kulik G. (2007) Epinephrine protects cancer cells from apoptosis via activation of PKA and BAD phosphorylation J Biol. Chem. 282(19):14094-100.
8)  Isabelle M. Berquin, Younong Min, Ruping Wu, Jiansheng Wu, Donna Perry, J. Mark Cline, Mike J. Thomas, Todd Thornburg, George Kulik, Iris J. Edwards, Ralph D’Agostino Jr., Adrienne Smith, Hao Zhang, Hong Wu, Jing X. Kang and Yong Q. Chen.  (2007) Modulation of Prostate Cancer Genetic Risk by Omega-3 and Omega-6 Fatty Acids.  J Clin Invest. 117(7):1866-1875.