This molecular epidemiology proposal is to continue applying knowledge of pharmacogenomic implications of gene expression of individual drug metabolizing enzymes to assess their role as risk markers for bladder cancer. We propose to use measures of whole body activity for drug metabolizing enzymes using the Pittsburgh cocktail that comprises CYP1A2 (caffeine), CYP2C19 (S-mephenytoin), CYP2D6 (debrisoquine), CYP2E1 (chlorzoxazone) and CYP3A4 (dapsone), as well as mRNA concentrations for each of these CYP enzymes in leukocytes and genotypic identification of known polymorphisms of CYP metabolizing enzymes to include CYP2D6 and CYP2E1. We will assess acetylation using a phenotypic trait measure (dapsone), supplemented by genotyping as well as GSTMI, and GSSTI using genotyping. Our initial work has provided evidence that high activity for CYPD6, low activity of CYP3A4, mutant alleles for acetylation and the null genotype for GSTMI are risk factors for bladder cancer, but to different extent for various forms of this cancer. We have also shown that high CYP2D6 activity is associated with mutations of the retinoblastoma (Rb) gene and low activity of CYP3A4 is independently associated with p53 mutations. Furthermore, different groups of risk factors relate to different mutational spectra of p53. We now propose to extend these observations.
Our specific aim i s to test the hypothesis that bladder cancer is comprised of a heterogeneous group of diseases in which different groups of associated risk factors relate to disease states that not only vary in etiology, but also in histopathological expression and natural history of the disease. This hypothesis will be evaluated in a case-control study of over 200 patients with incidence presentation of bladder cancer and over 200 controls matched for age, gender and ethnicity, in which environmental and constitutive variables will be related to the disease process. This study will involve a protocol that incorporates an exposure questionnaire, the Pittsburgh cocktail and blood sampling for mRNA quantitation and DNA genotyping. The disease process will be evaluated by clinical assessment and staging, identification of mutations of p53 and Rb genes, blinded histopathological review with grading and following the natural history for the disease. Collectively, these molecular epidemiology studies will improve our understanding of pathogenic mechanisms involved in different forms of bladder cancer and will expand our understanding of the regulation of the gene products that are responsible for drug metabolism in humans.
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