Mutation, loss of heterozygosity, and recombination of the p53 gene in mouse forestomach tumors induced by 2-amino-3,4-dimethylimidazo[4,5-f]quinoline.
2-Amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), a food mutagen, induces forestomach tumors in CDF1 mice. We established a polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis system to detect mutations in the mouse p53 gene exons 2-10, which encompass all five regions conserved among species, and a system to examine loss of heterozygosity (LOH) that uses newly identified polymorphisms between BALB/c and DBA mice, the parental strains of CDF1 mice. Four original forestomach tumors (one papilloma, two carcinomas, and one lymph-node metastasis) and four cell lines derived from four independent forestomach tumors were examined with the PCR-SSCP system and by polymorphism analysis. Of the four original tumors, the papilloma had a G-->A transition at the second position of codon 171, and one carcinoma had a G-->T transversion at the second position of codon 113 with loss of the wild-type allele, whereas the other two carcinomas had no detectable mutations. Of the four cell lines, two had a base substitution and LOH, and the other two had double mutations (a base substitution and a deletion). By amplification of the double mutations in a fragment, the two cell lines were shown to have four kinds of alleles, indicating induction of recombination within the p53 gene. Our results show that our PCR-SSCP analysis system is efficient for detecting p53 mutations in mouse genomic DNA and that alteration of the p53 gene plays a significant role in MeIQ-induced mouse forestomach carcinogenesis.
Ushijima
T
T
Carcinogenesis Division, National Cancer Center Research Institute, Tokyo, Japan.
Makino
H
H
Okonogi
H
H
Hosoya
Y
Y
Sugimura
T
T
Nagao
M
M
D000818:Animals; D001483:Base Sequence; D002273:Carcinogens; D002872:Chromosome Deletion; D016158:Genes, p53 / Q000235:genetics*; D006579:Heterozygote; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D009153:Mutagens; D009154:Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011804:Quinolines; D011995:Recombination, Genetic; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000235:genetics*; D014407:Tumor Cells, Cultured
D002273:Carcinogens; D009153:Mutagens; D011804:Quinolines; C036989:2-amino-3,4-dimethylimidazo(4,5-f)quinoline