Racial differences in CYP1B1 polymorphisms and risks for prostate cancer

Northern California Institute/Res/Edu, San Francisco CA

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Abstract

? DESCRIPTION (provided by applicant): In the USA, African-American (AfA) men have higher incidence and death rates due to prostate cancer when compared to Caucasians (Cau). The reasons for this discrepancy are unknown but studies have shown that single nucleotide polymorphisms (SNPs) of cytochrome P450 1B1 (CYP1B1), a gene that activates carcinogens, to be involved in prostate cancer pathogenesis. The goal of this project is to determine if CYP1B1 SNPs are risk factors for race-related prostate cancer and we hypothesize that these variants: 1) differ between AfA and Cau, 2) contribute to race-related prostate cancer and its progression, (3) are associated with prostate tissue levels, and (4) cause differences in enzyme levels and activity. Two specific aims are proposed to achieve the goals of the project. Aim #1 will investigate whether SNPs of CYP1B1 are risk factors for race- related prostate cancer. Blood DNA and prostate tissue will be collected from AfA and Cau patients with benign prostatic hyperplasia (BPH) and various stages and grades of prostate cancer; as well as blood DNA from age- matched, healthy male volunteers. The following experiments will be performed: (a) SNPs in the CYP1B1 promoter and coding region will be determined by sequence-specific PCR and direct genomic sequencing. The correlation of CYP1B1 SNPs and haplotypes with race and prostate cancer susceptibility and progression will be determined. (b) Localization of CYP1B1 in BPH and cancer tissues will be monitored by immunohistochemistry. By cross-referencing SNPs and haplotypes, the effects of polymorphisms on tissue CYP1B1 levels will be determined. In Aim #2, the mechanistic effects of CYP1B1 SNPs identified in Aim #1 will be investigated. The following experiments will be performed: (a) Construct CYP1B1 wildtype plasmids by cloning and generate polymorphic variants using site-directed mutagenesis, (b) Transfect promoter constructs into race-specific prostate cell lines and determine their effects on gene expression by luciferase reporter assay, (c) Transfect SNP constructs into E coli to express altered proteins and determine their enzymatic activity by utilizing a CYP1B1 assay. Successful completion of the proposed research will elucidate the (a) role of CYP1B1 polymorphisms as a risk factor and biomarker for race-related prostate cancer susceptibility and progression, and (b) effect of CYP1B1 variants on enzymatic levels and activities. Understanding the functional role of the CYP1B1 gene variants in race-specific prostate cancer will provide improved strategies for the management of this disease.