OBJECTIVETo investigate the expression of B cell specific MLV integration site-1 (Bmi-1) in colorectal cancer (CRC) and its correlation to the clinicopathological features and prognosis of CRC.

METHODSSixty CRC, 30 adenomas and 20 normal colorectal mucosal tissues were collected to detect the expression of Bmi-1 protein using immunohistochemistry, and the results were analyzed in comparison with the clinicopathological features and survival rate of patients.

RESULTSThe positivity rate of Bmi-1 expression in CRC tissue was 51.7%. In CRC, the rate of Bmi-1 overexpression was 25.0%, significantly higher than that in the adenomas and normal colorectal mucosal tissues (6.67% and 0%, respectively, P<0.05). The overexpression of Bmi-1 protein in CRC was obviously associated with distant metastasis and the TNM stage (P<0.05), but not with gender, age, tumor size, tumor site, histological type, differentiation degree and lymph node metastasis (P>0.05). But logistic regression analysis showed that Bmi-1 protein overexpression in CRC was associated only with distant metastasis (P<0.01,OR>1); Kaplan-Meier survival analysis showed that the survival rate of the patients with high Bmi-1 expression was significantly lower than that in patients with low expression (P<0.05).

CONCLUSIONThe overexpression of Bmi-1 protein was significantly correlated to the tumorigenesis, metastasis and prognosis of CRC, and may serve as an indicator for evaluating the prognosis of CRC.