Analysis of radiation-induced bystander effects between lung normal and cancer cells

Ikeda, Hiroko; Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko; Kanai, Tatsuaki*; Kobayashi, Yasuhiko

The purpose of this study is to detect radiation-induced bystander effects between lung normal and cancer cells using co-culture system. In our experiments, human lung normal fibroblasts WI-38 line and human lung cancer cells H1299/wt line which is genetically modified to produce normal p53 proteins in their DNA damage response were used. Cells were irradiated with carbon-ion broad beams (LET = 108 keV/m, Dose = 0.5 Gy) or Co--rays (LET = 0.2 keV/m, Dose = 0.5 Gy), then survival rates of bystander cells after 6- or 24-hours co-culture with irradiated cells were calculated using colony formation assay. When we co-cultured irradiated H1299/wt with non-irradiated WI-38, it was found that survival rates of WI-38 increased from 10% to 20% after 24-hours co-culture. Consequently, it was suggested that some factors were released from irradiated H1299/wt to promote cell growth and adhesion of bystander cells.