Effect of knocking down Smoothened (Smo) expression by specific siRNA in human gastric carcinoma cells

Objective To study the expression level of Smoothened(Smo)gene in MGC803 gas- tric cancer cells and the vital role of Smo gene in the proliferation and apoptosis of human gastric carcino- ma cells.Methods Using Western blot and semi-quantitative RT-PCR techniques,the expression levels of Smo protein and mRNA in MGC803 gastric cancer cells was detected.Three small fragments of siRNA chemically synthesized in vitro against Smo mRNA were transfected into MGC 803 gastric cancer cells by positive liposomal transfection methods,and intracellular Smo mRNA expression was detected by RT-PCR, which could be interfered by siRNA.The influences on proliferation and apoptosis of gastric cancer MGC cells were studied by flow cytometry and MTT after intracellular Smo mRNA being degraded.Results There was overexpression of Smo protein and mRNA in MGC 803 cells.At 48 h after transfection,the ex- pression level of Smo mRNA in MGC 803 cells of Smo siRNA-1 group was decreased by about 61.7% as compared with other groups.Meanwhile,after 24h of transfection,the cell proliferation in Smo siRNA-1 group was decreased notably as compared with controls.After 48h of transfection,the apoptosis rate in Smo siRNA-1 group was 23.6%,significantly higher than in controls.Conclusion Growth of MGC 803 gastric cancer cells is related to the abnormal expression of Smo gene.Inhibition of Smo gene expression can in- hibit proliferation and induce apoptosis in human gastric carcinoma cell-MGC803.Smo gene may play a key role in proliferation and apoptosis of human gastric carcinoma cells.