低温等离子体联合辐射对三种癌细胞系放射增敏效应的研究

目的 探讨低温等离子体对人肝癌细胞系HepG2、非小细胞肺癌细胞系A549及人宫颈癌细胞系HeLa的放射增敏作用及其机制。方法 应用克隆形成实验观察低温等离子体对3种细胞的放射增敏作用;流式细胞仪分析3种细胞周期分布、凋亡率及活性氧含量;Western blot法检测单纯照射(R组)、单纯等离子体作用(P组)及其联合辐射(P+R组)对3种细胞中Bcl-2、Caspase-3蛋白表达的影响。结果 低温等离子体对HepG2、A549及HeLa细胞均有放射增敏作用,放射增敏比(SER_D0)分别为1.28、1.32、1.29。HepG2、A549及HeLa细胞P+R组G₂/M期比例、凋亡率及活性氧含量与R组比较均明显增高(t_G2/M期=9.52、8.24、9.53,P<0.05;t_凋亡率=10.67、38.56、6.74,P<0.05;t_{活性氧含量}=9.41、15.42、13.53,P<0.05)。HepG2和A549细胞P+R组G₂/M期比例、凋亡率及活性氧含量与P组比较均明显升高(t_G2/M期=8.75、20.37,P<0.05;t_凋亡率=8.43、9.99,P<0.05;t_{活性氧含量}=4.82、5.27,P<0.05)。3种癌细胞中P+R组Bcl-2蛋白表达较R组降低,而Caspase-3蛋白表达升高。结论 低温等离子体可提高HepG2、A549及HeLa细胞系的放射敏感性,其对HepG2及A549细胞系的放射增敏机制可能与抑制亚致死损伤修复,使细胞周期阻滞在G₂/M期,以及提高细胞内ROS水平诱导细胞凋亡有关。

Radiosensitization effect of low-temperature plasma on human malignant cells

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(SER_D0)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.