Toxic effects of Vitamin C combined with temozolomide on glioma cells and its mechanism

Abstract

Objective: To investigate the toxic effects of vitamin C (VC) combined with temozolomide (TMZ) on gliomas and its mechanism. Methods: Human glioma cells BMG-1 and SHG44 cells were cultured in vitro, specifically divided into control group (without VC and TMZ), TMZ group (0.2 mmol/L), VC (0.5 mmol/L)+TMZ(0.2 mmol/L) group and TMZ(0.2 mmol/L TMZ)+U0126(10 μmol/L)group, each experiment was repeated three times. Cell survival rate was detected by MTT assay; Cell apoptosis was detected by flow cytometry and Annexin V-FITC/PI staining; Reactive oxygen species (ROS) levels were detected by ROS detection kit, and Western blot was used to detect the expression levels of proteins related to apoptosis, autophagy and ERK pathway. Results: Compared with the control group, the survival rate of glioma cells in the TMZ group was decreased significantly(P＜0.05). Compared with the TMZ group, the survival rate of glioma cells in the VC+TMZ group was decreased significantly(P＜0.01), the cell apoptosis rate was increased, and the expressions of Bax, Cleaved caspase-3 and Cleaved PARP protein were increased, while the expression of Bcl-2 was decreased. The ROS level and autophagy rate were decreased, while the expression of LC3-II/LC3-1 was decreased, and the expression of p62 was increased in the VC+TMZ group (all P＜0.05). At the same time, VC combined with TMZ decreased the expression level of p-ERK1/2-related protein in BMG-1 and SHG44 cells, and increased the apoptosis rate (P＜0.05). Conclusion: VC combined with temozolomide can enhance the toxicity of glioma cells. This effect is to promote apoptosis and inhibit temozolomide-mediated autophagy through the regulation of the ERK signaling pathway.