DNA polymerase beta is known to be involved in repair of DNA damage. Frequent mutation of its gene in the segment encoding amino acids 149-297 has been reported in colorectal cancer. To investigate whether mutation in this region is available as a genetic marker for colorectal cancer, 11 primary tumors and 4 liver metastases from 11 patients were examined by fragment length analysis and single-strand conformation polymorphism (SSCP) analysis of reverse-transcription polymerase chain reaction (RT-PCR) products. Although allelic imbalance in the p53 and DCC genes were observed in ten out of eleven primary tumors and all liver metastases using a dinucleotide repeat polymorphism, mutation was not detected in the DNA polymerase beta mRNA. Neither was it detected in seven colon cancer cell lines. Present results suggest that mutation in this region is uncommon in colorectal cancers and is not a useful genetic marker for colorectal cancer.

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