Effects ofγ-secretase inhibitor DAPT on the proliferation and apoptosis of esophageal cell lines

OBJECTIVE:To investigate the effect of inhibiting Notch signaling pathway on the proliferation and apoptosis of esophageal cancer cell lines through DAPT.METHODS:γ-secretase inhibitor DAPT was administrated to block Notch signaling pathway in cultured esophageal cancer cell line Eca109and TE-1.The proliferation and apoptosis of both esophageal cancer cell lines were detected by CCK8and flow cytometry(FCM),respectively.Real-time polymerase chain reaction(PCR)was performed to assess mRNA expression of Notch receptors and Notch target gene Hes-1.In addition,cyclin D1and Bcl-2protein were detected by Western blot.RESULTS:The proliferation of Eca109and TE-1was significantly inhibited by DAPT in a time-dependent and dose-dependent manner.Under the treatment with 5μmol/L DAPT,the inhibitory ratio of Eca109for 72hwas(61.8±5.3)%and the inhibitory ratio of TE-1for 96hwas(59.8±2.9)%,while in control group the inhibitory ratio was(17.2±2.6)%and(7.0±2.1)%(P=0.000 2and P0.000 1),respectively.DAPT induced the apoptosis of Eca109and TE-1.The apoptosis rate of Eca109and TE-1in treatment group at 24h was(18.24±2.60)%and(20.21±5.90)%,which was significantly higher than the apoptosis rate of Eca109and TE-1in control group that was(10.49±2.27)%(P=0.017 8)and(8.00±2.84)%(P=0.032 1).At 48h,the apoptosis of Eca109and TE-1in treatment group were(21.77±5.82)%and(32.14±5.92)%also significantly increased than that in control group which was(9.74±3.38)%(P=0.036 4)and(12.59±3.72)%(P=0.008 4).Expression of Notch2,Hes1and Cyclin D1was down-regulated by DAPT treatment.Additionally,DAPT promoted the expression of Bcl-2in Eca109.The expression of Bcl-2in TE-1was inhibited by DAPT treatment.CONCLUSIONS:γ-secretase inhibitor DAPT can inhibit the proliferation and induce the apoptosis of esophageal squamous carcinoma cell lines and its mechanisms may involve inhibiting Notch signaling and regulating the expression of Cyclin D1and Bcl-2.Blockage of Notch signaling pathway may offer a new strategy for the treatment of esophageal squamous cell carcinoma.