RT Journal Article
SR Electronic
T1 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
JF Cancer Research
JO Cancer Res
FD American Association for Cancer Research
SP 3531
OP 3536
VO 55
IS 16
A1 Hein, David W.
A1 Doll, Mark A.
A1 Rustan, Timothy D.
A1 Ferguson, Ronald J.
YR 1995
UL http://cancerres.aacrjournals.org/content/55/16/3531.abstract
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 &gt; O-acetylation &gt; 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.