Effect of resveratrol on proliferation of telmozolamine resistant glioblastoma and mechanism

Abstract

Objective To investigate the effect of resveratrol on the proliferation of glioblastoma resistant to temozolamine (TMZ) and the relationship between cell cycle and drug resistance genes expression. Methods U87 cell line was adopted to induce TMZ glioma model (U87-TMZ) by increasing the concentration of temozolomide. Methyl thiazol tetrazolium (MTT) assay was used to detect the proliferation of drug-resistant cell lines. Flow cytometry was used to detect the change of U87-TMZ cell cycle by resveratrol. Western blotting was used to detect the expression of Cyclin D1, topoisomerase (TOPOⅡ)α, glutathione-s-transferase (GST)-π, O6-methylguanine-DNA-methyltransferase (MGMT), and P-glycoprotein (P-gp). Results U87 glioma cells were stably stimulated with 20 μg/ml temozolamine for 6 months, and the U87-TMZ model was successfully constructed. Compared with the control group (DMSO group) and the blank group, the inhibition of proliferation of glioma cells was significantly decreased in 24 h in U87-TMZ model treated with 40 μg/ml resveratrol (experimental group) (P=0.014). Resveratrol inhibited the U87-TMZ cell cycle in a different period as compared with the control group, resulting in prolongation of the G1 phase and a decrease in the division phase. Western blotting analysis showed that resveratrol had different expression of drug resistance genes. The expression of Cyclin D1, TOPOⅡα, GST-π and MGMT proteins was significantly decreased in U87-TMZ group (experimental group) as compared with U87 group (P=0.002, 0.007, 0.031). Before and after treatment with resveratrol in the U87-TMZ group (experimental group), the expression of P-gp gene was not significantly different (P=1.043). The content of Cyclin D protein in U87-TMZ group was related to the change of resveratrol resistance genes. After up-regulating the expression of Cyclin D, the expression of TOPOⅡα, GST-π, MGMT and P-gp was statistically significantly increased (P= 0.001). Conclusion Resveratrol inhibits tumor cell proliferation by affecting the expression of Cyclin D protein and regulating U87-TMZ cell cycle. The mechanism may be related to the reduction of the sensitivity of the drug resistance of TOPO Ⅱ α, GST-π and MGMT gene expression. Key words: Resveratrol; Glioblastoma; Temozolamide; Drug resistance