Expression of Bmi-1 gene in esophageal carcinoma cell EC9706 and its effect on cell cycle, apoptosis and migration

Abstract

Previous studies have shown that Bmi-1 is overexpressed in a variety of tumors, suggesting that Bmi-1 plays an important role in tumorigenesis. In this study, we investigated the effect of Bim-1 siRNA on cell proliferation, cell cycle, cell apoptosis and migration of human esophageal carcinoma EC9706 cells, and explored its potential mechanisms. Bmi-1 small interfering RNA (siRNA) was transferred into EC9706 cells. Then, cell proliferation was measured using cell counting kit-8 (CCK-8), cell cycle and cell apoptosis were analyzed by flow cytometry, cell migration ability was detected using Boyden chamber assay, and the mRNA and protein expression levels of Bmi-1, p16, Bcl-2, Bax, and MMP-2 were determined using real-time polymerase chain reaction (PCR) and Western blot analysis, respectively. Bmi-1 siRNA treatment significantly inhibited the expression of Bmi-1 at both mRNA and protein levels in EC9706 cells. Cell proliferation rate decreased dramatically in the Bmi-1 siRNA treated group than in the untreated group and in the scrambled siRNA treated group (both P < 0.001). In Bmi-1 treated group, the percentage of cells at G(0)/G(1) stage was 71.93%, which was higher than that in the untreated group (47.36%) or scramble siRNA treated group (48.47%) (both P < 0.001). Early cell apoptosis rate also increased significantly in the Bmi-1 siRNA treated group (both 17.32%) than in the untreated group (2.61%) and in the scramble siRNA treated group (2.73%) (both P < 0.001). Further experiment suggested that downregulation of Bmi-1 led to less cell migration. In EC9706 cells transfected by Bmi-1 siRNA, the expression levels of p16 and Bax increased, while the expression level of Bcl-2 decreased. Bmi-1 downregulation in esophageal carcinoma cells inhibits cell proliferation, cell cycle, and cell migration, while increases cell apoptosis. These results suggest that Bmi-1 is a potential molecular target of treating esophageal cancer.