Notch Signaling Pathway Blocked by γ-secretase Inhibitor and Its Effect on the Growth and Apoptosis of SKOV3 Cells

Objective To determine the effect and mechanism of γ-secretase inhibitor DAPT on the growth and apoptosis of human ovarian carcinoma SKOV3 cells. Methods The effect of γ-secretase inhibitor DAPT was tested in vitro using SKOV3 cells. Its inhibition effect on cell proliferation was determined by CCK-8 assay. The cell apoptosis was detected by AO/EB double staining and flow cytometry. The expression of Notch1 mRNA and protein was detected by RT-PCR and Western blot. Results Compared with controls, 5 μmol/L, 10 μmol/L and 20 μmol/L of DAPT showed an effect of cell growth inhibition in a dose-dependent manner, with 19.87%, 28.38%, and 46.67% of 24 h inhibitory rates, respectively. Dose-dependent effect of DAPT on cell apoptosis was also evident, with (5.80 ± 0.98)%, (12.96 ± 4.99)%, (30.88 ± 7.63)%, and (42.98 ± 1.46)% apoptosis rates for the control, 5 μmol/L, 10 μmol/L and 20 μmol/L DAPT groups, respectively. RT-PCR analysis demonstrated that the expression of Notch1 mRNA decreased significantly in the DAPT groups, with an inhibition rate of 10.23%, 20.50％, and 38.83％ for the three DAPT groups, respectively. Western blot results demonstrated that the expression of Notch1 protein decreased significantly, with an inhibition rate of 12.89%, 27.47%, and 49.84% for the three DAPT groups, respectively. Conclusion γ-secretase inhibitor DAPT can block Notch signaling pathway, inhibit proliferation, and induce apoptosis of SKOV3 cells through down-regulation of the expression of Notch1.