title: Effect of rapid human N-acetyltransferase 2 haplotype on DNA damage and mutagenesis induced by 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx).
abstract: Heterocyclic amines such as 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx) are dietary carcinogens generated when meats are cooked well-done. Bioactivation includes N-hydroxylation catalyzed by cytochrome P4501A2 (CYP1A2) followed by O-acetylation catalyzed by N-acetyltransferase 2 (NAT2). Nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human CYP1A2 and either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles were treated with IQ or MeIQx to examine the effect of NAT2 genetic polymorphism on IQ- or MeIQx-induced DNA adducts and mutagenesis. MeIQx and IQ both induced decreases in cell survival and significantly (p<0.001) greater number of endogenous hypoxanthine phosphoribosyl transferase (hprt) mutants in the CYP1A2/NAT2*4 than the CYP1A2/NAT2*5B cell line. IQ- and MeIQx-induced hprt mutant cDNAs were sequenced and over 85% of the mutations were single-base substitutions with the remainder exon deletions likely caused by splice-site mutations. For the single-base substitutions, over 85% were at G:C base pairs. Deoxyguanosine (dG)-C8-IQ and dG-C8-MeIQx adducts were significantly (p<0.001) greater in the CYP1A2/NAT2*4 than the CYP1A2/NAT2*5B cell line. DNA adduct levels correlated very highly with hprt mutants for both IQ and MeIQx. These results suggest substantially increased risk for IQ- and MeIQx-induced DNA damage and mutagenesis in rapid NAT2 acetylators.
authors.affiliation: Department of Pharmacology & Toxicology, James Graham Brown Cancer Center and Center for Environmental Genomics and Integrative Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
authors.forename: Kristin J
authors.initials: KJ
authors.lastname: Metry
authors.forename: Jason R
authors.initials: JR
authors.lastname: Neale
authors.forename: Mark A
authors.initials: MA
authors.lastname: Doll
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Howarth
authors.forename: J Christopher
authors.initials: JC
authors.lastname: States
authors.forename: W Glenn
authors.initials: WG
authors.lastname: McGregor
authors.forename: William M
authors.initials: WM
authors.lastname: Pierce
authors.forename: David W
authors.initials: DW
authors.lastname: Hein
mesh_terms: D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000235:genetics*; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004249:DNA Damage; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009153:Mutagens / Q000633:toxicity; D011804:Quinolines / Q000633:toxicity*; D011810:Quinoxalines / Q000633:toxicity*; D014162:Transfection
chemical_list: D009153:Mutagens; D011804:Quinolines; D011810:Quinoxalines; C029216:2-amino-3-methylimidazo(4,5-f)quinoline; C036990:2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline; D001191:Arylamine N-Acetyltransferase; C478900:NAT2 protein, human