Relationship between microsatellite instability and deficiency of DNA mismatch repair system in lung carcinoma

Objectiye To investigate the relationship between microsatellite instability (MSI) and mismatch repair gene (MMR) in lung carcinoma,and to analyze its action in lung carcinogenesis.Methods DNA was extracted from 50 cases of lung carcinoma and adjacent normal tissue.SSCP was used to detect MSI.Immunohistochemistry was performed to measure the expression of hMLH1 and hMSH2 protein in lung carcinoma.Results Of the 50 cases of lung carcinoma,14 with high MSI,21 with low MSI,and 15 with microsatellite stability,0 with MSI in normal group (P = 0.000).Lack of hMLH1 and hMLH2 staining was found in 37 of 50 (74 %) and 16 of 50 (32 %) lung carcinoma tissues with MSI,respectively; but both of hMLH1 and hMSH2 positive staining was found in the lung carcinoma tissues with MSS.Conclusion MSI appears to be associated with lung carcinogenesis,and inactivation of either hMLH1 or hMSH2 may be responsible for MSI,suggesting that MSI may become one of diagnosis indexes of lung carcinoma. Key words: DNA mismatch repair; ,Microsatellite instability; Lung neoplasms