Effects of γ-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 Eca109 and TE-1.The proliferation and apoptosis of both esophageal cancer cell lines were detected by CCK8 and 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 D1 and Bcl-2 protein were detected by Western blot. RESULTS: The proliferation of Eca109 and TE-1 was significantly inhibited by DAPT in a time-dependent and dose-dependent manner. Under the treatment with 5 μmol/L DAPT, the inhibitory ratio of Eca109 for 72 h was (61.8±5.3)% and the inhibitory ratio of TE-1 for 96 h was (59.8±2.9)%, while in control group the inhibitory ratio was (17.2±2.6)% and (7.0±2.1)% (P=0.000 2 and P<0.000 1), respectively. DAPT induced the apoptosis of Eca109 and TE-1.The apoptosis rate of Eca109 and TE-1 in treatment group at 24 h was (18.24±2.60)% and (20.21±5.90)%, which was significantly higher than the apoptosis rate of Eca109 and TE-1 in control group that was (10.49±2.27)% (P=0.017 8) and (8.00±2.84)% (P=0.032 1).At 48 h, the apoptosis of Eca109 and TE-1 in 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, Hes1 and Cyclin D1 was down-regulated by DAPT treatment.Additionally, DAPT promoted the expression of Bcl-2 in Eca109.The expression of Bcl-2 in TE-1 was 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 D1 and Bcl-2.Blockage of Notch signaling pathway may offer a new strategy for the treatment of esophageal squamous cell carcinoma.