Effect of proteasome inhibitor Oprozomib on ovarian cancer cells to cis-platinum / 解放军医学杂志

ABSTRACT

Objective To study the enhancement of sensitivity to cisplatin (DDP) mediated by the addition of proteasome inhibitor Oprozomib (OZ) in ovarian cancer cells. Methods SKOV3/DDP and A2780/DDP cells were cultured in vitro, and the logarithmic growth phase cells were used in this study. To study the effect of OZ on drug-resistant cell viability, a series dilutions of OZ (0, 3, 9, 27, 81, 243, 729, 2181, and 6561 nmol/L) was used. The effect of DDP was also investigated with a series titrations (0, 3, 9, 27, 81, 243, 729, 2181 and 6561 nmol/L) in the presence of 50 μl of 500 nmol/L OZ. CCK-8 method was used to detect cell viability; flow cytometry was used to detect the apoptosis rate after treated with DDP+OZ. The experiments were divided into the control group and OZ group to detect the effects of OZ on the activity of proteasome chymotrypsin (CT-L), the synthesis of intracellular glutathione (GSH); the expression of intracellular glutathione synthetase (GSS) was examined using western blotting. The experiments were divided into the control group, DDP group, OZ group, DDP+OZ group, DDP+OZ+GSH group and DDP+OZ+Tempol group to detect the ROS level and apoptosis rate. Results The IC50 of OZ to SKOV3/DDP and A2780/ DDP cells were 140 and 350 nmol/L, respectively; In the presence of OZ, the IC50 of DDP to SKOV3/DDP and A2780/DDP cells were 154 and 232 nmol/L, respectively. The apoptosis rate of ovarian cancer cells increased significantly (P<0.01) after treated with DDP+OZ together. OZ can inhibit the CT-L activity of the proteasome in a dose-dependent manner and can inhibit GSH synthesis and GSS protein expression (P<0.01). The decrease of GSH level leads to the obstruction of ROS clearance, and the ROS level was significantly reduced by the ROS scavenger Tempol (P<0.05, P<0.01). Tempol significantly inhibits the apoptosis induced by DDP+OZ (P<0.01). Conclusion OZ enhanced sensitivity of SKOV3/DDP and A2780/DDP to cis-platinum by inhibiting the generation of GHS which resulted in the accumulation of ROS.