Prostate cancer is a significant health problem among American men. Curative treatments for advanced disease are currently not available and novel treatment approaches are needed. Recombinant forms of TRAIL (tumor necrosis factor related apoptosis inducing factor) have been considered as novel anti-tumor agents but prostate cancer cells are relative resistant to soluble TRAIL. Resistance is overcome by sub-toxic doses of doxorubicin which downregulate the anti-apoptotic protein c-FLIP or by an adenovirus expressing membrane TRAIL. Neither approach is selective for malignant cells and will require restriction of either doxorubicin or TRAIL to a specific target population. It is our hypothesis that combination of doxorubicin with tissue-specific expression of TRAIL from the prostate-specific promotor probasin will be an effective therapeutic approach against prostate cancer. To support this hypothesis and identify underlying mechanisms of TRAIL resistance in prostate cells, the following specific aims will be investigated: (1) To test the hypothesis that the mechanism of doxorubicin-mediated downregulation of c-FLIP involves cell cycle dependent ubiquitination. Cells that are sorted into G0/G1, S and G2/M populations will be analyzed for levels of c-FLIP, ubiquitination, and TRAIL susceptibility. (2) To test the hypothesis that the TRAIL expressing adenovirus (AdTRAIL) overcomes resistance by permitting intracellular interaction of ligand and agonistic TRAIL receptors resulting in formation of an intracellular death inducing signaling complex. The role of c-FLIP in providing resistance to AdTRAIL will be investigated in PC3 cells stably overexpressing long and short isoforms of the protein. Intracellular location of TRAIL receptors and interaction with ligand, caspases and c-FLIP will be analyzed by confocal microscopy. Protein interactions are also determined by immunoprecipitation/immunoblotting. (3) To test the hypothesis that combination of chemotherapy and prostate-specific gene therapy is an effective approach against prostate cancer. The effectiveness of specificity of an adenovirus-expressing TRAIL from the prostate-specific promotor ARR2PB will be tested in cells with a functional androgen receptor and non-prostate cells. The apoptotic potential of virus alone or in combination with doxorubicin will be determined in vitro. The toxicity and effectiveness of AdARR2PBTRAIL alone or in combination with doxorubicin will also be tested in subcutaneous xenografts in athymic mice.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA102218-02
Application #
6863702
Study Section
Special Emphasis Panel (ZRG1-DT (01))
Program Officer
Arya, Suresh
Project Start
2004-04-01
Project End
2009-02-28
Budget Start
2005-03-01
Budget End
2006-02-28
Support Year
2
Fiscal Year
2005
Total Cost
$229,950
Indirect Cost
Name
Medical University of South Carolina
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
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White-Gilbertson, Shai; Rubinchik, Semyon; Voelkel-Johnson, Christina (2008) Transformation, translation and TRAIL: an unexpected intersection. Cytokine Growth Factor Rev 19:167-72
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White, Shai J; Lu, Ping; Keller, Gina M et al. (2006) Targeting the short form of cFLIP by RNA interference is sufficient to enhance TRAIL sensitivity in PC3 prostate carcinoma cells. Cancer Biol Ther 5:1618-23
El-Zawahry, Ahmed; McKillop, John; Voelkel-Johnson, Christina (2005) Doxorubicin increases the effectiveness of Apo2L/TRAIL for tumor growth inhibition of prostate cancer xenografts. BMC Cancer 5:2