Expression of hMSH2 gene and mutant p53 in sporadic digestive tract tumors

Objective To investigate the role of mutated mismatch repair gene hMSH2 and mutant p53 gen e in the carcinogenesis and development of sporadic digestive tract tumors. Methods hMSH2 gene in normal and tumor tissue of 30 digestive tract tumor specimens was examined using polymerase chain reaction- single strand conformation polymorphis m (PCR- SSCP) silver staining. The PCR product with an abnormal strand was sequ enced directly. Mutant p53 protein in the tumor tissue was analyzed immunohisto chemically. Results Six patients were identified as having mutated strands, three on hMSH2 exon 1 an d three on hMSH2 exon 5. DNA sequencing revealed that all 6 patients had mutate d basic groups that led to decrease in function of the hMSH2 protein. Forty per cent (12/30) of patients were p53 positive. The frequency of mutated hMSH2 in p 53 positive patients (41.7%) was significantly higher than in p53 negative pati ents (5.6%,P<0.05).Conclusion The mutation of hMSH2 plays an important role in the carcinogenesis and developm ent of digestive tract tumors through stimulating p53 mutation.