In vivo study of resveratrol regulating Wnt signaling pathway to enhance temozolomide against gliomas

Abstract

Objective To investigate the effect of resveratrol (Res) on temozolomide (TEM) against gliomas in vivo. Methods Human glioma cell line T98G was transplanted into BALB/C-nu female nude mice to establish orthotopic human glioma cell transplanted models. Five d after modeling, the 48 successfully modeled nude mice were randomly divided into solvent control group, Res group, TEM group, combination drug group, Wnt signaling pathway agonist group, and Wnt signaling pathway inhibitor group(n=8); and dimethyl sulfoxide (10 mg/kg), Res (10 mg/kg), TEM (25 mg/kg), Res (10 mg/kg+TEM (25 mg/kg), Res (10 mg/kg)+TEM (25 mg/kg)+lithium chloride (2 mg/kg), and Res (10 mg/kg)+TEM (25 mg/kg)+IWR-1 (5 mg/kg) were given, respectively, once/d for 30 d. During the administration, the survival status of nude mice in each group was continuously observed, tumor volume was measured by MR imaging every 5 d. Thirty d after administration, TUNEL was used to detect the apoptosis of tumor cells, and immunofluorescence was used to detect the immunofluorescent intensity of O6-methylguanine-DNA methyltransferase (MGMT) and β-catenin in the tumor tissues. Western blotting was used to detect the protein expression levels of Wnt signaling pathway-related proteins (Wnt2, and β-catenin), MGMT, and glycogen synthase kinase 3β (GSK3β). Results As compared with the TEM group, the combination drug group and Wnt signaling pathway inhibitor group had significantly decreased tumor volumes 20, 25, 30, and 35 d after modeling (P<0.05); as compared with the combination drug group, the Wnt signaling pathway inhibitor group had significantly decreased tumor volumes while Wnt signaling pathway agonist group had significantly increased tumor volumes 20, 25, 30, and 35 d after modeling (P<0.05). TUNEL showed that the apoptosis rate of tumor cells in the combination drug group and Wnt signaling pathway inhibitor group was significantly increased as compared with that in the temozolomide group (P<0.05); as compared with that in the TEM group, the apoptosis rate of tumor cells in the Wnt signaling pathway inhibitor group was significantly increased while that in the Wnt signaling pathway agonist group was statistically decreased (P<0.05). Western blotting results showed that as compared with those in the combination drug group, the protein expression levels of Wnt2, β-catenin, and MGMT in the Wnt signaling pathway inhibitor group were significantly reduced, and GSK-3β protein expression level was significantly increased; while the protein expression levels of Wnt2, β-catenin, and MGMT in the Wnt signaling pathway agonist group were significantly increased, and GSK-3β protein expression level was significantly decreased (P<0.05). Conclusion Res inhibits Wnt signaling pathway by reducing expressions of Wnt2 and β-catenin, leading to decrease in MGMT expression, thereby enhancing the anti-glioma effect of TEM. Key words: Resveratrol; Temozolomide; Wnt signaling pathway; Glioma