The Novel EZH2 Inhibitor,GSK126,Exhibits Antitumor Effect In Vitro And In Vivo

Objective:Cancer is disease which death rate ranks the highest in the world. Therefore, researches of its mechanism remain one of the hotspots in biomedical research recently. Enhancer of zeste homolog 2 (EZH2) are closely related to the tumor development, it overexpression can lead to tumor genesis and deterioration. GSK126, a new EZH2 inhibitor, inhibits the overexpression of EZH2 and subsequently suppress tumor development and metastasis. It has been reported that GSK126 exhibits inhibitory effect on non-solid tumors, but its effect on solid tumors is not clear. In the present study, we explore the anti-tumor effect of GSK126 on solid tumors as well as its mechanisms.Methods:Gastric cancer cell line MGC803 and Human lung adenocarcinoma cell line A549 were treated with or without GSK126. SRB assay and Annexin V-/PI assay were used to evaluate the cell proliferation and apoptosis. Transwell and wound healing assays were conducted to detect cell migration. Human umbilical vein endothelial cells (HUVEC) tube formation assay and Chick embryo chorioallantoic membrane (CAM) assay were performed to assess the effects of GSK126 on angiogenesis in vitro and in vivo, respectively. The mRNA levels of VEGF-A were detected by Qualitative PCR, and the protein levels of VEGF-A were detected both by Western blot analysis and immunohistochemistry. We also use Xenograft model and Metastasis model to explore GSK126 anti-tumor effect and its mechanism. Results:GSK 126 inhibited cell migration in both MGC803 and A549 in a dose-dependent manner, as revealed by Transwell and wound healing assays. The effects of GSK 126 were similar to gefitinib at the same doses. Moreover, GSK126 at the dose of 20 and 50 μM inhibited angiogenesis both in vitro and in vivo. GSK126 also down-regulated VEGF-A mRNA expression in a dose-dependent manner. Furthermore, the protein level of VEGF-A was similarly inhibited after GSK126 administration in MGC803 and A549 cells. In vivo imaging assay revealed that GSK126 at the dose of 200 mg/kg significantly inhibited cancer cell migration. The combination of GSK126 and Gefitinib decreased the cell proliferation, increased the cell apoptosis. In vivo, the combination of GSK126 and Gefitinib can inhibit MGC-803 tumor growth. Conclusions:GSK126 inhibits cell migration and angiogenesis in solid tumor cell lines likely through down regulation of VEGF-A expression. GSk126 may be used as a potential anti-cancer drug in solid tumor. The combination of GSK126 and Gefitinib can effectively inhibit MGC-803 and A549 cell proliferation and induce cell apoptosis, its mechanism needs further study.