Notch3 siRNA enhances chemosensitivity of colon cancer cells to topotecan

Objective:To elucidate the relationship between Notch3 expression and chemosensitivity of human colon carcinoma cell line SW620 to topotecan.Methods: Notch3 siRNA was transfected into SW620 cells,and the expression of Notch3 in SW620 cells was examined by Western blotting.After transfected with Notch3 siRNA for different time periods,SW620 cells were further treated with topotecan,and the proliferation of SW620 cells was detected by MTT assay;the apoptosis of SW620 cells was detected by Hoechst 33342 staining and flow cytometry.Caspase-3 activation in SW620 cells was examined by caspase-3 activation kit.Results: Notch3 siRNA transfection remarkably inhibited Notch3 protein expression in SW620 cells.The IC50 of topotecan in Notch3 siRNA-transfected group was significantly decreased compared with that in the Ctrl siRNA group(P0.05).Silence of Notch3 expression in SW620 cells by Notch3 siRNA remarkably promoted apoptosis(P0.05) and caspase-3 activation(P0.05) of SW620 cells induced by topotecan.Conclusion: Notch3 down-regulation by siRNA in SW620 cells can enhance the chemosensitivity cells to topotecan.