Effects of downregulation of SIRT3 expression on proliferation and apoptosis in esophageal squamous cell carcinoma EC9706 cells and its molecular mechanisms.

To investigate the effect of downregulation of SIRT3 expression on cell proliferation and invasion in esophageal squamous cell carcinoma (ESCC) EC9706 cells, and to explore its possible molecular mechanisms, we transfected siRNA targeting SIRT3 into EC9706 cells, and then divided cells into three groups: untreated, control siRNA and SIRT3 siRNA groups. The expression levels of SIRT3 protein were detected in different groups by western blotting. The effect of SIRT3 siRNA on cell proliferation was investigated using the CCK-8 kit. The changes of cell apoptosis were examined by flow cytometry. Finally, the expression levels of cell proliferation and apoptosis related proteins such as p21, Bcl-2 and Bax were determined by western blotting. SIRT3 siRNA effectively down-regulated the expression of SIRT3 protein in EC9706 cells, and the reduced expression of SIRT3 significantly inhibited cell proliferation and induced cell apoptosis. Most notably, the SIRT3 depletion markedly increased the expressions of p21 and Bax proteins but reduced Bcl-2 protein expression. The proliferation inhibition and apoptosis of EC9706 cells mediated by SIRT3 downregulation may be closely associated with the expression levels of p21, Bcl-2 and Bax proteins.