The objective of the proposed study is to determine how the N-acetyltransferase (NAT) polymorphism, a genetic metabolic trait involved in the metabolism of arylamines, influences individual susceptibility to arylamine-induced DNA damage and carcinogenesis. The finding that there are two polymorphic NATs in humans, each with multiple alleles, adds a new dimension to the investigation of the role of acetylator status in human sensitivity to exogenous chemicals.In this proposal, molecular biological and cell culture techniques will be used to transfect specific alleles of human NATs into mammalian cells (COS cells) and then to determine the susceptibility of the resulting genotype to arylamine-induced DNA damage. Current studies using acetylator congenic and acetylator, Ah-responder double congenic mouse lines will be extended to additional carcinogens and tissues. Further studies will focus on the interaction of the NAT polymorphism with two alternative oxidation pathways for arylamine carcinogens: cytochrome P450 1A subfamily monooxygenases and prostaglandin synthase (PHS) co-oxidation. Inbred and congenic mouse lines that are being developing in this laboratory will be used to model the interaction of NAT with cytochrome P450 1A and NAT with PHS as determinants of human susceptibility to colon and other extra-hepatic cancers. The technique of 32P-postlabeling (and the HPLC method previously developed in this laboratory) will be used to determine genotype-specific and tissue-specific patterns of DNA damage resulting from carbocyclic aromatic amines (e.g. 2-aminofluorene) and heterocyclic aromatic amines (e.g. IQ) produced in cooked foods. An inbred mouse model will also be constructed to determine the contribution of PHS and combinations of PHS and NAT to extra-hepatic DNA damage induced by these aryl- and heterocyclic amines. This model will also be used as a tool to study pharmacological interventions in PHS activity and their effects on prevention or reduction of DNA damage and carcinogenesis.
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