Dihydroartemisinin enhances sensitivity of nasopharyngeal carcinoma HNE1/DDP cells to cisplatin-induced apoptosis by promoting ROS production
Objective To investigate the effect of dihydroartemisinin(DHA)for enhancing the inhibitory effect of cisplatin(DDP)on DDP-resistant nasopharyngeal carcinoma cell line HNE1/DDP and explore the mechanism.Methods CCK-8 method was used to assess the survival rate of HNE1/DDP cells treated with DHA(0,5,10,20,40,80,and 160 μmol/L)and DDP(0,4,8,16,32,64,128 μmol/L)for 24 or 48 h,and the combination index of DHA and DDP was calculated using Compusyn software.HNE1/DDP cells treated with DHA,DDP,or their combination for 24 h were examined for cell viability,proliferation and colony formation ability using CCK-8,EdU and colony-forming assays.Flow cytometry was used to detect cell apoptosis and intracellular reactive oxygen species(ROS).The expression levels of apoptosis-related proteins cleaved PARP,cleaved caspase-9 and cleaved caspase-3 were detected by Western blotting.The effects of N-acetyl-cysteine(a ROS inhibitor)on proliferation and apoptosis of HNE1/DDP cells with combined treatment with DHA and DDP were analyzed.Results Different concentrations of DHA and DDP alone both significantly inhibited the viability of HNE1/DDP cells.The combination index of DHA(5 μmol/L)combined with DDP(8,16,32,64,128 μmol/L)were all below 1.Compared with DHA or DDP alone,their combined treatment more potently decreased the cell viability,colony-forming ability and the number of EdU-positive cells,and significantly increased the apoptotic rate,intracellular ROS level,and the expression levels of cleaved PARP,cleaved caspase-9 and cleaved caspase-3 in HNE1/DDP cells.N-acetyl-cysteine pretreatment obviously attenuated the inhibitory effect on proliferation and apoptosis-inducing effect of DHA combined with DDP in HNE1/DDP cells(P<0.01).Conclusion DHA enhances the growth-inhibitory and apoptosis-inducing effect of DDP on HNE1/DDP cells possibly by promoting accumulation of intracellular ROS.