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. The main objective of this research is to confirm the role of PhIP metabolism in colon cancer by demonstrating that the NAT2 and CYPIA2 phenotype, as well as GSTM1 and CYPIA1 genotype are related to the level of PhIP-DNA adducts formed in humans administered dietary relevant levels of 14C-PhIP. These factors are important to study because they represent enzymes that are thought to be important in PhIP metabolism based on rodent studies. The outcome of this work will be additional proof that heterocyclic amines such as PhIP are involved in colon cancer since these enzymes are active in the metabolism of heterocyclic amines. Additionally, this work will show whether genotype or phenotype are potentially useful markers of PhIP susceptibility for colon cancer. We have collected data in humans to establish the role of PhIP metabolism in colon cancer by determining the relationship between NAT2 and CYPIA2 phenotype, as well as GSTM1 and CYPIA1 genotype and the level of PhIP-DNA adducts formed in humans. This was accomplished by administering very low levels of 14C-labeled PhIP to human subjects with a diagnosis of colon cancer who are scheduled for surgery. Data so far from 10 subjects indicates that SULT, NAT2 and CYP1A2 phenotypes influence adduct levels in the colon. A larger, more statistically significant, study is planned to verify the findings. There is a need to perform similar work in other cancers such as breast cancer, prostate cancer and lung cancer. In each of these areas, the disease toll is great, the prevention strategies are limited by a knowledge deficit in the areas of disease etiology and metabolism pathway and exposure information is incomplete.
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