2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine induces a higher number ofaberrant crypt foci in Fischer 344 (rapid) than in Wistar Kyoto (slow) acetylator inbred rats
M. Purewal et al., 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine induces a higher number ofaberrant crypt foci in Fischer 344 (rapid) than in Wistar Kyoto (slow) acetylator inbred rats, CANC EPID B, 9(5), 2000, pp. 529-532
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the most abundant
heterocyclic amine carcinogen in the human diet and is a colon carcinogen
in the rat. N-Acetyltransferase-2 (NAT2) catalyzes the conversion of PhIP a
nd other heterocyclic amines to a DNA-reactive form. NAT2 has a polymorphic
distribution in humans and other mammals, including rats. The rapid NAT2 g
enotype has been shown to be associated with increased colorectal cancer ri
sk in some, but not all, human epidemiological studies. This investigation
was designed to study the role of acetylator genotype in PhIP-induced colon
carcinogenesis using aberrant crypt foci (ACF) as an intermediate biomarke
r, Five-week-old male, rapid-acetylator Fischer 344 (F344) rats and slow-ac
etylator Wistar-Kyoto (WKY) rats were fed the semipurified AIN76A diet with
0.01% PhIP, 0.04% PhIP, or no PhIP (control) for 8 weeks. PhIP induced ACF
in both rapid-and slow-acetylator rats; 0.04% PhIP induced more ACF than 0
.01% PhIP, There was no difference in the number of ACF between rapid- and
slow-acetylator rats that were fed 0.01% PhIP, However, 0.04% PhIP induced
2-fold higher ACF and a greater dose-dependent increase in PhIP-induced ACF
in the rapid-acetylator F344 rats compared with the slow-acetylator WKY ra
ts. The results support human epidemiological studies showing higher risk f
or colorectal cancer in rapid acetylators who frequently consume meat that
is very well done.