[Expression and clinical significance of Mucin and E-cadherin in colorectal tumors].

Background & Objective: Mucin (MUC), a glycoprotein with high molecular weight, can lubricate and protect the epithelium. E-cadherin (E-cad) is helpful in keeping the polarity and integrity of the epithelium. The abnormal expression of Mucin and E-cad is involved in the genesis of many tumors. This study was to investigate the expression of MUC1, MUC2, MUC5AC and E-cad in different colorectal tumor tissues, and explore their correlations to clinicopathologic features of colorectal cancer and the correlations of MUC1, MUC2, and MUC5AC expression to E-cad expression.

Methods: The expression of MUC1, MUC2, MUC5AC and E-cad in 150 specimens of normal colorectal mucosa, 150 specimens of colorectal adenoma and 150 specimens of colorectal adenocarcinoma was detected by immunohistochemistry. Patients' survival was analyzed by Kaplan-Meier method. The correlations of MUC1, MUC2, and MUC5AC expression to E-cad expression were analyzed by spearman's rank correlation.

Results: The positive rates of MUC1 were 0.07% in normal colorectal mucosa, 12.7% in colorectal adenoma, and 45.3% in colorectal adenocarcinoma. Those of MUC2 were 100%, 90.0% and 52.6%, respectively. Those of MUC5AC were 8.7%, 30.7% and 44.0%, respectively. Those of E-cad were 98.7%, 82.0% and 54.0%, respectively. In colorectal adenocarcinoma, the expression of MUC1 and MUC2 was correlated to tumor differentiation, invasion, lymph node metastasis and Dukes' stage (P<0.05); the expression of MUC5AC was correlated to tumor differentiation and invasion (P<0.01); the expression of E-cad was correlated to tumor differentiation (P<0.01). The 5-year survival rate was significantly higher in MUC1-negative group, MUC2-positive group and E-cadherin-positive group than in their counterparts (P<0.05). In colorectal adenocarcinoma, MUC1 expression was negatively correlated to E-cad expression (r=-0.234, P=0.004), MUC2 and MUC5AC expression were positively correlated to E-cad expression (r=0.170, P=0.038; r=0.198, P=0.015).

Conclusions: In colorectal adenocarcinoma, MUC expression is obviously correlated to E-cad expression. The up-regulation of MUC1 and MUC5AC expression and the down-regulation of MUC2 and E-cad expression may be involved in the genesis of colorectal tumors and reflect the prognosis to a certain extent.