Harmine Regulates Gastric Cancer Cell Proliferation And Apoptosis Through PTEN/Akt/MDM2/Cox-2 Pathway

BackgroundHarmine(HM)has been shown can block angiogenesis and inhibit the growth of lung cancer;Inhibiting breast cancer cell proliferation,invasion and metastasis;Inhibiting the proliferation of hepatocellular carcinoma cells and inducing its apoptosis.However,There is no relative study on the effect of harmine on the progression of gastric cancer.Our preliminary study found that harmine could inhibit gastric cancer cell proliferation,metastasis and infiltration through down-regulation of COX-2.However,the mechanism of down-regulation of COX-2 is unclear.ObjectiveThis article investigated the effect of harmine on the expression of PTEN,phosphorylated Akt(p-Akt),phosphorylated MDM2(p-MDM2)and COX-2 under different concentration and signal factor inhibitors to determine the mechanism of harmine inhibiting gastric cell proliferation and inducing apoptosis through downregulation of COX-2.MethodHuman gastric cell lines SGC-7901 and MKN-45 were cultured in RPMI-1640 culture medium.Sub-confluent cell cultures were treated with harmine at a final concentration of 2,4,8,16 and 32 μg/ml.MTT colorimetric assay was used to identify the cell proliferation rates;Hoechst staining was used to observe the morphologic changes of apoptotic cells;Flow Cytometry was used to detect the cell apoptosis rates and Western blot analysis was used to detect the expression of PTEN,phosphorylated Akt,MDM2,COX-2.ResultsHarmine significantly inhibited SGC-7901 and MKN-45 cell proliferation in a dose-and time-dependent manner.Hoechst staining showed typical apoptotic morphologic changes in both SGC-7901 and MKN-45 cells treated with harmine.Harmine induced cell apoptosis in a dose-dependent manner.Harmine dosedependently increased PTEN expression,whereas inhibited Akt and MDM2 phosphorylation and COX-2 expression in SGC-7901 and MKN-45 cells.The PTEN inhibitor bpv(Hopic)effectively inhibited the high expression of PTEN induced by harmine and reversed the effect of harmine on the expression of Akt,MDM2 phosphorylation and COX-2.The Akt inhibitor MK2206 combined with harmine inhibited the expression of Akt,MDM2 phosphorylation and COX-2 and the combination effect was greater than that of harmine alone.The MDM2 inhibitor Nutlin-3 combined with harmine inhibited MDM2 phosphorylation and COX-2 expression and the combination effect is greater than harmine alone.ConclusionHarmine inhibits the progression of gastric cancer by inhibiting the expression of COX-2 in gastric cancer cells through the PTEN / Akt / MDM2 signal transduction pathway.