Polycomb group protein Bmi1 expression in colon cancers predicts the survival.

Colorectal cancer is the second leading cause of cancer-related death in the United States and the fourth leading cause worldwide. Currently, there is still no excellent predictor of the survival. Polycomb-group proteins Bmi1 is regarded as a "stemness" gene involved in the maintenance of stem cells, malignant transformation, and biologic aggressiveness of several human carcinomas. We examined the expression of the Bmi1 in colon cancer and its relevance to other characteristics, especially the 5-year survival of colon cancer. The expression of Bmi1 was examined in colorectal carcinoma (n=98) by using real-time polymerase chain reaction. Expression was correlated with clinicopathologic variables, 5-year overall survival (OS) rates. We for the first time found that high expression of Bmi1 was significantly associated with poor survival. Fourfold Table Chi-square Test analysis revealed that Bmi1 expression was closely related to TNM stage and histologic grade, while not relevant to age. In summary, the high expression of polycomb-group protein Bmi1 is an essential and important predictor of colorectal cancer prognosis.