Expressions Of DNA Mismatch Repair Protein HMLH2 And HMLH1 In The Occurrence Of Colorectal Carcinoma

Objective: Colorectal carcinoma is one of the most frequent tumors in China. While the mechanism of its occurrence is not clarifed, it is important to study the tumorigenesis in order to make early diagnose and decide treatment method. Colorectal tumorigenesis is a complex processing involving mutationgs of many genes, so normal cells have a complete gene repair system in order to protect the stability of genome. Mismatch repair (MMR) is a important method in the whole repair system, and among them hMSH2 and hMLH1 are the most important. In this study, we detected the protein expressions of mismatch repair genes hMSH2 and hMLH1 in colorectal carcinoma,adjacent mucosa to carcinoma and normal colorectal mucosa to analyze the roles of their abnormal expressions in colorectal carcinogenesis.Method: colorectal carcinoma with clear pathological diagnosis from 163 patients were collected. Among the patients, mucosa surrounding carcinoma were obtained from 40 patients and mucosa of non-carcinoma were obtained from 37 patients. Immunohistochemistry was used to detect the protein expressions of hMSH2 and hMLH1. SPS13.0 statistic software was used to analyze the correlation of their abnormal expressions to colorectal carcinoma.Results: In carcinoma group, adjacent mucosa group, and normal mucosa group, the rates of hMSH2 expression were 46.6%(76/163),27.5%(11/40)and 21.6%(8/37). There was significant difference between the carcinoma group and the later two groups(P<0.05). In carcinoma, the rates of hMSH2 expression in colon and rectum were 55.8%(67/120)and 20.9%(9/43), there was significant difference between the two groups(P<0.05); the expressions of hMSH2 had no relationship with sex,age,differentiation,infiltrate depth and lymph node metastasis(P>0.05).In carcinoma group, adjacent mucosa group, and normal mucosa group, the positive rates of hMLH1 expression were 20.9%(34/163),5%(2/40)and 5.4%(2/37). There was significant difference between the carcinoma group and the later two groups(P<0.05). In carcinoma, the rates of hMLH1 expression in colon and rectum were 25%(30/120)and 9.3%(4/43), there was significant difference between the two groups(P<0.05); the rates of hMLH1 expression in elder group,middle group and young group were 26.3%(21/80),23.7%(9/39)and 9.09%(4/44), there was significant difference between the elder and young groups(P<0.05); the expressions of hMLH1 had no relationship with sex,differentiation,infiltrate depth and lymph node metastasis(P>0.05).Conclusions:1. The expressions of hMSH2 and hMLH1 proteins in colorectal carcinoma were up-regulated.2. There were different nosogenesis in colon and rectal carcinoma.3. The incidence of DNA mismatched may be increased as the age increasing.The expression of hMLH1 protein was up-regulated in elder patients, which indicated the opportunity of mismatch increases with age. It may be the colorectal carcinoma's nosogenesis.4. Detecting the expressions of hMSH2 and hMLH1 are very helpful to predict colorectal carcinoma.