Tissue distribution of N‐acetyltransferase 1 and 2 catalyzing the N‐acetylation of 4‐aminobiphenyl and O‐acetylation of N‐hydroxy‐4‐aminobiphenyl in the congenic rapid and slow acetylator Syrian hamster

Abstract

N-acetyltransferase 1 (NAT1) and 2 (NAT2) enzymes catalyzing both deactivation (N-acetylation) and activation (O-acetylation) of arylamine carcinogens such as 4-aminobiphenyl (ABP) were investigated in a Syrian hamster model congenic at the NAT2 locus. NAT2 catalytic activities (measured with p-aminobenzoic acid) were significantly (P < 0.001) higher in rapid than slow acetylators in all tissues (except heart and prostate where activity was undetectable in slow acetylators). NAT1 catalytic activities (measured with sulfamethazine) were low but detectable in most tissues tested and did not differ significantly between rapid and slow acetylators. ABP N-acetyltransferase activity was detected in all tissues of rapid acetylators but was below the limit of detection in all tissues of slow acetylators except liver where it was about 15-fold lower than rapid acetylators. ABP N-acetyltransferase activities correlated with NAT2 activities (r2 = 0.871; P < 0.0001) but not with NAT1 activities (r2 = 0.132; P > 0.05). Levels of N-hydroxy-ABP O-acetyltransferase activities were significantly (P < 0.05) higher in rapid than slow acetylator cytosols for many but not all tissues. The N-hydroxy-ABP O-acetyltransferase activities correlated with ABP N-acetyltransferase activities (r2 = 0.695; P < 0.0001) and NAT2 activities (r2 = 0.521, P < 0.0001) but not with NAT1 activities (r2 = 0.115; P > 0.05). The results suggest widespread tissue distribution of both NAT1 and NAT2, which catalyzes both N- and O-acetylation. These conclusions are important for interpretation of molecular epidemiological investigations into the role of N-acetyltransferase polymorphisms in various diseases including cancer.

2-Amino-3,8-Dimethylimidazo-[4,5-f]Quinoxaline–Induced DNA Adduct Formation and Mutagenesis in DNA Repair–Deficient Chinese Hamster Ovary Cells Expressing Human Cytochrome P4501A1 and Rapid or Slow Acetylator N-Acetyltransferase 2

“…N-acetyltransferase activities were measured with the human NAT2-selective substrate sulfamethazine using HPLC to separate N-acetylsulfamethazine product from sulfamethazine substrate as described previously (25). N-hydroxy-MeIQx O-acetyltransferase assays were determined by HPLC using modifications of an assay described recently (26). Briefly, reaction mixtures containing equal amounts of cell lysate protein, 1 mg/mL deoxyguanosine, 100 Amol/L N-hydroxy-MeIQx (Toronto Research Chemicals), and 1 mmol/L acetyl-CoA were incubated at 37jC for 10 min and stopped by the addition of watersaturated ethyl acetate.…”

Induction of Human Arylamine N-Acetyltransferase Type I by Androgens in Human Prostate Cancer Cells

“…Both classes of carcinogens induce prostate tumors in animal models (8,9). Recently, it has been reported that human prostate tissue, as well as prostate cells in culture, contains measurable levels of the enzymes required for the activation of arylamine carcinogens (10)(11)(12)(13)(14).…”

Prevalence of Non-Cytochrome P450-Mediated Metabolism in Food and Drug Administration-Approved Oral and Intravenous Drugs: 2006-2015

“…(Testa and Mayer, 2006;Uetrecht and Trager, 2007;Long and Cravatt, 2011;Yang et al, 2011;Bachovchin and Cravatt, 2012;Oda et al, 2015). Additionally, metabolites arising from conjugative enzymes (phase II metabolism), including uridine 59-diphospho-glucuronosyltransferases (UGT) (Tukey and Strassburg, 2000;Oda et al, 2015), N-acetyl transferases (Hein et al, 2006), glutathione S-transferases (Armstrong, 1997;Eaton and Bammler, 1999;Salinas and Wong, 1999;Sheehan et al, 2001), sulfotransferases (Strott, 2002;Riches et al, 2009), and methyltransferases (Petrossian and Clarke, 2011), are also frequently identified.…”