Abstract: Objective: To investigate the effect of Lycium barbarum polysaccharides (LBP) combined with cisplatin (DDP) on oxidative injury, apoptosis and apoptosis-related protein expression in hunman lung adenocarcinoma cell line A549. Methods: The cells were divided into a control group, a DDP (6 mg/L) group, an LBP (8 mg/L) group and an LBP (8 mg/L) + DDP (6 mg/L) group. CCK-8 method was used to detect the effect of separate and combined treatment with LBP and DDP on the cell viability of A549. Superoxide dismutase activity was measured by xanthine oxidase method, malondialdehyde content by thiobarbituric acid method, the content of glutathione (GSH) by dithio-dinitrobenzoic acid method, the content of reactive oxygen species (ROS) and the rate of apoptosis by flow cytometry, and the expression of apoptosis-related proteins Bcl-2, Bax and caspase-3 by Western blot. Results: LBP significantly enhanced the inhibitory effect of DDP on the survival rate of A549 cells (P < 0.01). DDP resulted in a significant reduction of superoxide dismutase (SOD) activity and GSH content (P < 0.01), and a significant increase of MDA and ROS contents in A549 cells (P < 0.01). Compared with the DDP group, the levels of SOD, GSH and malondialdehyde in the LBP + DDP group were not significantly changed (P > 0.05), while the content of ROS was significantly reduced (P < 0.01).Treatment with DDP, LBP or their combination could significantly promote cell apoptosis (P < 0.01) and lower the expression of Bax and caspase-3 as well as Bax/Bcl-2 ratio (P < 0.01). Conclusion: The combination of LBP and DDP can obviously promote apoptosis of A549 cells, and its underlying mechanism is mainly related to the regulation of apoptosis-related protein expression by both of them.

Key words: Lycium barbarum polysaccharide, cisplatin, lung cancer, antioxidant, apoptosis