Study on bystander effects induced by carbon-ion beams between normal fibroblasts and lung cancer cells

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

The purpose of this study is to detect bystander effect between normal fibroblasts and lung cancer cells with different p53 status and to elucidate its mechanisms. In the study, we used human lung normal fibroblasts WI-38 line and human lung cancer cells H1299/wtp53 line that can produce normal p53 proteins in their DNA damage response. We irradiated cells with carbon-ion broad beams (18.3 MeV/u, LET = 108 keV/m; Dose = 0.5 Gy) or -rays (Dose = 0.5 Gy), then calculated survival rates of bystander cells after 6 or 24 hours cocultute of irradiated and non-irradiated cells. When we cocultured irradiated H1299/wtp53 cells with non-irradiated WI-38 cells, it was found that survival rates of WI-38 cells were not decreased at all. Consequently, it was suggested that bystander factors were not released from irradiated H1299/wtp53 cells.