Assessment of Radiation-Induced Bystander Effect in Astrocyte-Glioblastoma Cell Lines br

In this study, the bystander effect on reactive oxygen derivatives (ROS) production and DNA damage level in normal astrocytic cells was examined using a co-culture method mimicking boundary conditions between normal astrocytes and cancer cells in the glioblastoma (GBM) tumor. SVG-p12 astrocytes and U87-MG GBM cells were co-cultured. ROS production and DNA damage were determined using flow cytometer after ionize radiation (IR) treatments of 2Gy and 4Gy doses. The one-way analysis of variance (ANOVA) was used to evaluate differences be-tween means of groups. Spearman's rank correlation coefficient was used for correlation analysis. We found that the percentages of Reactive Oxygen Species (ROS) productions were increased in all experimental control groups after 2Gy (U87-MG: 51.6%, SVG-p12: 34.3%, coSVG-p12: 19.1% and coU87-MG: 50.2%) and 4Gy (U87-MG: 41.2%, SVG-p12: 21.8%, coSVG-p12: 22.3% and coU87-MG: 26.5%) treatments. In addition, the increased radiation dose and pro-longed incubation period induced Double Strand Break (DSB) in the U87-MG cells co-cultured with astrocyte cells (p< 0.05). The transfer of medium irradiated with 4Gy dose increased ROS levels but not DSB in co-culture. Our study shows that RIBE arising from astrocyte cells in the irradiation area may induce ROS production and DSB in GBM cells. Cellular debris of radiation-disrupted astrocytes may cause RIBE altering response of GBM cells to IR.