Atorvastatin prolongs the lifespan of radiation‑induced reactive oxygen species in PC-3 prostate cancer cells to enhance the cell killing effect.

Abstract

Studies have reported that atorvastatin (ATO) may increase the radiosensitivity of malignant cells. However, the influence of ATO on reactive oxygen species (ROS) levels before and after irradiation has not been fully illustrated. In the present study, radiosensitivity was evaluated by a clonogenic assay and a cell survival curve and cell apoptosis was measured by flow cytometry. ROS were detected by a laser scanning confocal microscope and flow cytometry with a DCFH-DA probe. NADPHoxidases(NOXs) and superoxide dismutase (SOD)proteins were detected by immunoblotting, and total SOD activity was measured using an SODkit. We also conducted transient transfection of NOX2 and NOX4genes to increase intracellular ROS generation and applied SODmimetic tempol to enhance ROS elimination ability. Our results demonstrated that, with ATO-alone treatment, the survival fractions of irradiated PC-3 cells were significantly decreased. Meanwhile, the apoptosis rate of the irradiated cells increased significantly (P<0.05). The ROS levels of the study group decreased obviously before irradiation (P<0.01), however, the radiation-induced ROS of the study group was at a high level even when irradiation had been terminated for 2h (P<0.01). Moreover, NOX2 and NOX4levels and total SOD activity decreased (P<0.01), while the levels of SOD1 were stably maintained (P>0.05). On the other hand, the decreased survival fractions and high radiation-induced ROSlevels were abrogated by increasing the level of NOXs by gene transfection or by enhancing the ability of SOD utilizing the addition of tempol. In conclusion, ATO enhanced the cell killing effect of irradiation by reducing endogenous ROS levels and prolonging the lifespan of radiation‑induced ROS via a decrease in the level of NOXs and SOD activity.