[Expression and significance of Bmi-1 and Ki67 in colorectal carcinoma tissues].

BACKGROUND & OBJECTIVE: Bmi-1, a putative oncogene, is a member of the polycomb group genes, and is expressed in many human tumors. Ki67 is an important nuclear antigen associated with cell proliferation. This study was to investigate the expression, significance and correlation of Bmi-1 and Ki67 in colorectal carcinoma (CRC) tissues.

METHODS

Protein expressions of Bmi-1 and Ki67 in sixty CRC, 30 adenomas and 20 normal colorectal mucosal tissues were detected using immunohistochemistry. Correlations of the expression of Bmi-1 and Ki67 to clinicopathological features and survival of patients were analyzed.

RESULTS

The expression rates of Bmi-1 and Ki67 were 25.0%, 6.7%, 0% and 18.3%, 3.3% and 0% in CRC, adenomas and normal colorectal mucosal tissues, respectively. The expression of Bim-1 and Ki67 were significantly higher in CRC than in adenomas and normal colorectal mucosal tissues (P<0.05). Chi-square test revealed that the overexpression of Bmi-1 protein in CRC was correlated to distant metastasis (P<0.01) and TNM stage (P<0.05), while the overexpression of Ki67 protein was associated with age, distant metastasis and TNM stage (P<0.05). Further logistic regression analysis showed that only distant metastasis was correlated with Bmi-1 overexpression (P<0.01,OR>1), and only age was correlated with Ki67 overexpression(P<0.05, OR<1). Kaplan-Meier survival analysis showed that the survival was significantly shorter in CRC patients with overexpression than low expression of Bmi-1 and Ki67 (P<0.05).

CONCLUSIONS

Overexpression of Bmi-1 and Ki67 protein are significantly correlated with tumorigenesis, metastasis and prognosis of CRC. Bmi-1 and Ki67 might be used to predict the prognosis of CRC. Bmi-1 might regulate the expression of Ki67 indirectly in CRC patients.