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Genetic alterations in rat colon tumors induced by heterocyclic amines
Author(s) -
Toyota Minoru,
Ushijima Toshikazu,
Kakiuchi Hideki,
Canzian Federico,
Watanabe Masatoshi,
Imai Kohzoh,
Sugimura Takashi,
Nagao Minako
Publication year - 1996
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/(sici)1097-0142(19960415)77:8<1593::aid-cncr26>3.0.co;2-u
Subject(s) - exon , microbiology and biotechnology , microsatellite instability , microsatellite , gene , intron , carcinogenesis , single strand conformation polymorphism , biology , mutation , gene mutation , genetics , locus (genetics) , allele
BACKGROUND In rat colon tumors induced by the cooked food mutagens 2‐amino‐ 1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) and 2‐amino‐3‐methylimidazo[4,5 ‐f]quinoline (IQ), ras and p53 alterations are rarely detected. To investigate the roles of the APC gene and microsatellite instability (MI) in PhIP‐induced colon carcinogenesis, mutations of the APC gene and alterations of microsatellites were examined. METHODS Complementary DNA sequence of the rat APC gene were determined by polymerase chain reaction (PCR) using primers based on the human APC sequence. PCR‐single strand conformation polymorphism (SSCP) analysis was performed using primers based on sequences of flanking introns and exon 15. Microsatellite alterations were also analyzed using 85 microsatellite sequences dispersed through most of the rat chromosomes. RESULTS Five mutations in the APC gene were detected in four of eight PhIP‐induced rat colon tumors. All five mutations involved deletion of a guanine base in a 5′‐GGGA‐3′ sequence. Only 2 of 13 IQ‐induced colon tumors had mutations of the APC gene and these were base substitution mutations. Seven of eight PhIP‐induced colon tumors had microsatellite alterations in at least one locus, whereas no alterations were observed in the IQ‐induced colon tumors. CONCLUSIONS The specific 5′‐GGGA‐3′ to 5′‐GGA‐3′ mutation and MI demonstrated in this study are strong evidence of a mutational fingerprint of PhIP.