Expression of hMSH2, hMLH1 Protein in Sporadic Colorectal Cancer and Corresponding Normal Tissue

ABSTRACT

PURPOSE: DNA mismatch repair gene is responsible for hereditary nonpolyposis colorectal cancer. But it is not well known its role in sporadic colorectal cancer patients. We analysed normal hMSH2, hMLH1 protein expression in colorectal adenocarcinoma tissues and corresponding normal tissues to find out the role of mismatch repair gene in sporadic colorectal cancer by Western blotting. METHODS: Normal hMSH2 and hMLH1 protein expression was studied on 25 colorectal cancer and corresponding normal tissue by Western blot with hMSH2 and hMLH1 monoclonal antibody. Normal protein band was expressed on 100 kD in hMSH2 and 87 kD in hMLH1. SW480 and LoVo cell line was used as positive and negative control for hMSH2 and LoVo and SW480 as positive and negative for hMLH1. And we analysed the relation between the hMSH2, hMLH1 protein expression and clinicopathological parameters. RESULTS: It was 2 cases (8%) that both hMSH2 and hMLH1 protein expression was not observed. Three cases (12%) were negative for hMSH2 and 2 cases (8%) for hMLH1. One or both hMSH2, hMLH1 protein expression was not observed in 7 cases (28%) in total. There was no correlation for proximal occurrence (25% vs 35%), young age (37.5% vs 23.5%) and lymph node metastasis (50% vs 47%). But poorly and mucinous differentiation was regarded as having relation with negative expression of hMSH2 and hMLH1 (50% vs 17.6%) but not significant statistically. CONCLUSION: Sporadic colorectal cancer with negative expression of normal hMSH2 and hMLH1 protein showed no relation to younger age, proximal site preference and lymph node metastasis. But it was suggested that mismatch repair gene protein was involved in cancer cell differentiation in sporadic colorectal cancer.