Radiosensitization effect of low-temperature plasma on human malignant cells

Abstract

Objective To evaluate the radiosensitization effect of low-temperature plasma on HepG2, A549, and HeLa cells. Methods Cells were divided into three groups, radiation group(R), plasma treatment group(P), and plasma plus radiation group (P+ R). After radiation, cell survival was detected by a cloning assay. Cell cycle distribution, apoptosis and ROS content were tested by flow cytometry. Western blot was used to measure the expressions of Caspase-3 and Bcl-2. Results Low-temperature plasma showed radiosensitization effects on three different human malignant cell lines with a sensitivity enhancement ratio(SERD0)of 1.28, 1.32 and 1.29. respectively. In these three different human malignant cell lines, compared with radiation alone group (R), the G2/M arrest, apoptosis rate and ROS level in the group P+ R were enhanced(the prolongation of G2/M arrest: t=9.52, 8.24, 9.53, P<0.05; the apoptosis rate: t=10.67, 38.56, 6.74, P<0.05; ROS content: t=9.41, 15.42, 13.53, P<0.05). In HepG2 cells and A549 cells, compared with group P, the prolongation of G2/M arrest, the apoptosis rate and ROS content of group P+ R were enhanced (the prolongation of G2/M arrest: t=8.75, 20.37, P<0.05; the apoptosis rate: t=8.43, 9.99, P<0.05; ROS content: t=4.82, 5.27, P<0.05). The expression level of Bcl-2 protein was downregulated in group P+ R; by contrast, the expression level of Caspase-3 protein in group P+ R was upregulated. Conclusions Low-temperature plasma can increase the radiosensitization of HepG2, A549 and HeLa cells with the enhancement of G2/M phase arrest, apoptosis induction and ROS generation. Key words: Radiosensitization; Low-temperature plasma; HepG2 cells; HeLa cells; A549 cells