Oncogenes are frequently found in a variety of human cancers. Studies in the Branch have been established to investigate the role of oncogenes in the etiology of carcinogen-induced human tumors. Bladder cancer was chosen as a model tumor for this investigation, since it is perhaps the best prototype of a chemically induced human tumor. In one study, smoking and environmental exposure information is being collected on 30 patients about to undergo resection of bladder tumors. Tumor tissue, blood and urine samples and questionnaire data have been collected on approximately 10 patients to date. Assays for oncogenes, such as transfection into NIH 3T3 cells and nude mice assays should begin shortly. In a second study, oncogene assays will be done on bladder tumor tissues resected from approximately 60 individuals with occupational exposures to the potent bladder carcinogens benzidine and beta-napthylamine; and compared to oncogene assays done on bladder tumor tissues resected from 100 individuals without such exposures. Individuals with exposure to these chemicals are rare, but samples of bladder tumor tissue from them are available in the form of paraffin-embedded tissue blocks made and stored following surgery. Recently, oncogene assays have been developed for use with these blocks, allowing us to determine the oncogene status of tumors resected many years ago from individuals with exposures to these powerful chemical carcinogens. All paraffin blocks have been retrieved for the exposed cohort of patients, and blocks and epidemiologic data are still being collected for the unexposed group. The primary assay to be used on these blocks utilizes the polymerase chain reaction to amplify the gene of interest followed by direct sequencing of the gene.
