PT  - JOURNAL ARTICLE
AU  - Hein, David W.
AU  - Doll, Mark A.
AU  - Rustan, Timothy D.
AU  - Ferguson, Ronald J.
TI  - Metabolic Activation of <em>N</em>-Hydroxyarylamines and <em>N</em>-Hydroxyarylamides by 16 Recombinant Human NAT2 Allozymes: Effects of 7 Specific <em>NAT2</em> Nucleic Acid Substitutions
DP  - 1995 Aug 15
TA  - Cancer Research
PG  - 3531--3536
VI  - 55
IP  - 16
4099  - http://cancerres.aacrjournals.org/content/55/16/3531.short
4100  - http://cancerres.aacrjournals.org/content/55/16/3531.full
SO  - Cancer Res1995 Aug 15; 55
AB  - Human polymorphic N-acetyltransferase (NAT2) catalyzes the N-acetylation of arylamine carcinogens and the metabolic activation of N-hydroxyarylamine and N-hydroxyarylamide carcinogens by O- and N,O-acetylation, respectively. Rapid and slow acetylator phenotype is regulated at the NAT2 locus, and each has been associated with differential risk to certain cancers relating to carcinogenic arylamine exposures. We examined arylamine N-acetylation, N-hydroxyarylamine O-acetylation, and N-hydroxyarylamide N,O-acetylation catalytic activities of 16 different recombinant human NAT2 alleles expressed in an Escherichia coli JM105 expression system. NAT2 alleles contained nucleic acid substitutions at G191A (Arg64→Gln), C282T (silent), T341C (IIe114→Thr), C481T (silent), G590A (Arg197→Gln), A803G (Lys268→Arg), G857A (Gly286→Glu), and various combinations of substitutions in the 870-bp NAT2-coding region. Expression of each NAT2 allele produced equivalent amounts of immunoreactive recombinant NAT2 protein with differential levels of N-, O-, and N,O-acetylation activity. Catalytic activities of each of the recombinant human NAT2 allozymes followed the relative order N-acetylation > O-acetylation > N,O-acetylation. Catalytic activation rates for the metabolic activation of N-hydroxy-2-aminofluorene and N-hydroxy-4-aminobiphenyl by O-acetylation and N-hydroxy-2-acetylaminofluorene by N,O-acetylation showed very strong correlations to the N-acetylation of 2-aminofluorene. NAT2 alleles with nucleic acid substitution T341C (NAT2*5A, *5B, *5C) expressed recombinant NAT2 allozymes, with the greatest reductions in metabolic activation of N-hydroxyarylamines and N-hydroxyarylamides by O- and N,O-acetylation, respectively. NAT2 alleles with nucleic acid substitutions G191A (NAT2*14A, *14B) and G590A (NAT2*6A, *6B) expressed recombinant NAT2 allozymes with more moderate reductions. NAT2 alleles with nucleic acid substitution G857A (NAT2*7A, *7B) expressed recombinant NAT2 allozymes with the smallest but yet significant reductions. NAT2 alleles with nucleic acid substitutions C282T (silent), C481T (silent), and A803G (Lys268→ Arg) expressed recombinant NAT2 allozymes that did not have significant reductions in the metabolic activations of N-hydroxyarylamines and N-hydroxyarylamides. The differential capacity for the metabolic activation of N-hydroxyarylamines and N-hydroxyarylamides by recombinant human NAT2 allozymes encoded by polymorphic NAT2 alleles supports the hypothesis that acetylator phenotype may predispose to cancers related to activation of N-hydroxyarylamine and N-hydroxyarylamide carcinogens. ©1995 American Association for Cancer Research.