Epigenetic changes in a PhIP-induced prostate cancer model in hCYP1A mice

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DESCRIPTION (provided by applicant): Prostate cancer is one of the most frequently diagnosed malignancies in developed countries and a leading cause of cancer-related death among men in the United States. Prostate cancer involves numerous risk factors, particularly age, race, and diet. Exposure to PhIP, a dietary carcinogen generated from high temperature cooking of meat and fish, has been associated with prostate cancer risk. In this study, we will investigate carcinogenesis of a PhIP-induced prostate cancer model in CYP1A-humanized (hCYP1A). The objectives are to determine the induction mechanism of DNMT1, a major methyltransferase enzyme involved in DNA methylation, and identify the promoter DNA hypermethylation of genes caused by the upregulated level of DNMT1. Based on previous studies and preliminary data, the hypotheses are that DNMT1 is induced by the Ras/MAPK/AP-1 and/or PI3K/Akt signaling pathway and that the upregulation of DNMT1 causes hypermethylation and inactivation of key regulatory and tumor suppressor genes in the prostate of the humanized mice. To test these hypotheses, three specific aims are proposed: (1) elucidate the mechanism of DNMT1 induction in hCYP1A mice at 1, 3, 7, and 14 days after PhIP treatment; (2) identify promoter DNA hypermethylation of key regulatory and tumor suppressor genes caused the elevated level of DNMT1 using methylation PCR array; and (3) investigate the relationship between DNMT1 upregulation in the early time- points (1 & 3 days) and the late stages (30 & 40 weeks) of PhIP-induced carcinogenesis. The proposed experiments will employ standard histological (H&E), immunohistochemical (IHC), and molecular techniques (Western Blotting & quantitative RT-PCR) as well as more specialized methods (Laser Capture Micro- dissection, Methylation Specific PCR, & DNA methylation PCR array). The study will reveal the induction mechanism of DNMT1 and the epigenetic changes caused by the PhIP carcinogen. Determining the molecular mechanism and alterations in the PhIP-treated hCYP1A mice will enhance our understanding of prostate carcinogenesis and cancer development.