Sinomenine sensitizes human gastric cancer cells to cisplatin through negative regulation of PI3K/AKT/Wnt signaling pathway

Sinomenine (SIN) has been reported its antitumor effects on various types of human cancers, but there is no available information regarding the antitumor effects of SIN and cisplatin on gastric cancer. Here, we examined the antitumor effects of SIN combined with cisplatin on gastric cancer cells as well as the underlying biological mechanisms. CCK-8 assay and Calcusyn 2.0 software analysis, Hoechst 33258 staining and flow cytometry, transwell assay showed that SIN and cisplatin synergistically inhibited growth, induced apoptosis, and suppressed invasion than did either drug alone in gastric cancer cells. Interestingly, no change in the AKT level was found, whereas SIN and cisplatin led to a dramatic decrease in p-AKT level compared with either alone treatment. SIN and cisplatin further decreased the Bcl-2, procaspase-3, and β-catenin, but increased Bax, cleaved dcaspase 3, MMP9, and MMP2 in combined group than in either alone group. Immunofluorescence staining showed again a significant decrease in nucleus β-catenin was found in combined group. These data suggested that SIN sensitizes human gastric cancer cells to cisplatin through negative regulation of PI3K/AKT/Wnt signaling pathway. In conclusion, SIN and cisplatin exerted synergistic antitumor effects in gastric cancer cells and might constitute a promising therapeutic approach for gastric cancer.