Assessment of radiation-induced bystander effect in astrocyte-glioblastoma cell lines

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 glioblas- toma (GBM) tumor. SVG-p12 astrocytes and U87-MG GBM cells were co-cultured. ROS production and DNA damage were deter- mined 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 analy- sis. 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.