Reduced expression level of mgmt mRNA and beta-catenin gene mutation in rat colon tumors.

BACKGROUND O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein and protects DNA from the biological effects of alkylating carcinogens. The purpose of this study was to investigate the association between the mRNA expression level of the Mgmt gene and mutation of the beta-catenin gene in rat colon tumors induced by azoxymethane (AOM) plus dextran sulfate sodium (DSS). MATERIALS AND METHODS Eleven tumor samples from rat colon treated by AOM plus DSS were examined. Mutation of the beta-catenin gene was identified by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. The expression level of Mgmt mRNA was determined by reverse transcription-PCR (RT-PCR). RESULTS Four out of five adeno-carcinoma samples bearing beta-catenin gene mutation (5 out of 11, 45%) displayed a decrease in expression levels of Mgmt mRNA (p<0.02). CONCLUSION These results suggest that the reduced expression of Mgmt mRNA and beta-catenin gene mutation may contribute to the development of rat colon tumors.