Anti-proliferation effect of BMI-1 in U937 cells with siRNA.

Polycomb protein BMI-1 is often overexpressed in various types of leukemia, and its depletion in those leukemic cells leads to cell proliferation arrest, differentiation, and apoptosis. These findings have led us to believe that Bmi-1 has potential as a therapeutic target for leukemia. In this study, we tested multiple sets of synthetic siRNA oligo pairs for downregulating the expression of Bmi-1 in U937 cells, and explored the possible biological effects of BMI-1 suppression on cell growth and proliferation. We found that one siRNA oligo pair can efficiently knock down BMI-1 in U937 cells as evaluated by real-time RT-PCR as well as Western blot analysis. Furthermore, we found that BMI-1 depletion leads to reduced cell growth and proliferation, and increased cell apoptosis. Our proof-of-principle findings confirm that Bmi-1 siRNA can be used as a therapeutic target of any Bmi-1 expressing leukemia and other cancer cells.