This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Abstract: Breast cancer is the leading cause of cancer related death in women between the ages of 40 and 55 and the second leading cause of cancer related death in women in the United States. Exposure to carcinogens in the environment, occupational setting, and diet are believed to be the reason for the discrepancy. Epidemiological studies demonstrate a positive association with breast cancer and cigarette smoke. Benzo(a)pyrene (B(a)P), a major component of cigarette smoke, has been shown to cause lung, liver, pancreatic, colon and breast cancer. B(a)P is biotransformed into reactive metabolites that produces DNA adducts and DNA strand breaks. Furthermore, B(a)P has been shown to transform human breast epithelial cells (MCF-10A)from a normal to a cancerous phenotype. Several OSCs Diallyl Sulfide (DAS), Diallyl Disulfide (DADS) and Diallyl Trisulfide (DATS) have been shown to prevent cancer by altering biotransformation. We hypothesize that these OSCs will prevent the transformation of normal human breast epithelial cells to a cancerous phenotype by altering the biotransformation of B(a)P thus preventing the production of B(a)P DNA adducts and the expression of genes involved in cell transformation. To test this hypothesis first we will treat MCF-10A cells with B(a)P and/or OSCs and determine if reactive metabolites are formed. Secondly, we will determine if B(a)P cause DNA strand breaks by comet assay analysis and DNA adducts via P32 Post labeling and if OSCs can prevent this DNA damage and enhance DNA repair over time. Next we will determine the ability of B(a)P to transform normal cell into a cancerous phenotype and the ability of OSCs to inhibit this transformation by treating the cells repeatedly with B(a)P and OSCs. The formation of colonies on soft agar will indicate the presence of transformed cells. Tumor development in nude mice implanted with these transformed cells will confirm neoplastic transformation. Finally, we will demonstrate that B(a)P and/or OSCs will alter the expression of genes associated with transformation and proliferation. Gene expression will be determined by Real Time PCR Array and confirmed by Western Blot Analysis. Results from this study will help elucidate the mechanism by which B(a)P causes breast cancer and how OSCs may prevent this cancer. Ultimately, better chemopreventive regimens and chemotherapeutic compounds would be developed for this research.