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Accumulation of K‐ Ras codon 12 mutations in the F344 rat distal colon following azoxymethane exposure
Author(s) -
McKinzie Page B.,
Parsons and Barbara L.
Publication year - 2011
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.20644
Subject(s) - azoxymethane , carcinogen , carcinogenesis , dna adduct , mutation , biology , colorectal cancer , aberrant crypt foci , medicine , microbiology and biotechnology , endocrinology , chemistry , cancer , biochemistry , gene , colonic disease
Azoxymethane (AOM) administration to F344 male rats is a widely used model of human colon carcinogenesis. The current study investigates quantitatively the accumulation of K‐ Ras codon 12 mutations following AOM exposure. Male, 6‐week‐old F344 rats were treated subcutaneously with 30 mg/kg body weight of AOM, and colon tissue was collected at 1, 8, 24, and 32 weeks after treatment. The K‐ Ras codon 12 GGT to GAT and GGT to GTT mutant fractions (MFs) were measured using allele‐specific competitive blocker polymerase chain reaction (ACB‐PCR). Between 1 and 32 weeks after AOM treatment, the K‐ Ras codon 12 GGT to GAT geometric mean MF in the rat colon increased significantly from 12.9 × 10 −5 to 145 × 10 −5 , and the GGT to GTT geometric mean MF increased significantly from 5.26 × 10 −5 to 180 × 10 −5 . K‐ Ras codon 12 GGT to GAT MF also increased significantly in AOM‐treated rat colon tissue at 1 week compared to controls (4.44 × 10 −5 ). The accumulation of the GGT to GAT MF long after the DNA adduct repair phase suggests that a portion of cells containing this mutation have a proliferative advantage, allowing them to accumulate as nascent tumors progress. Also, the GGT to GAT background MF increased in untreated rats, indicating that there is accumulation with age. The ACB–PCR assay generates quantitative data of cancer‐related mutations and thus provides insight into pathological processes following carcinogen exposure. Environ. Mol. Mutagen., 2011. © Published 2011 Wiley‐Liss, Inc.