Particle number- and LET-dependency of bystander effect through the gap junction signalling in human normal fibroblast cells exposed to heavy-ion beams

Matsumoto, Yoshitaka*; Hamada, Nobuyuki*; Aoki, Mizuho*; Wada, Seiichi*; Funayama, Tomoo; Sakashita, Tetsuya; Kakizaki, Takehiko; Kobayashi, Yasuhiko; Furusawa, Yoshiya*

When cells were irradiated with ionizing radiation, non-irradiated cells around irradiated cells showed the same biological effect, for example apoptosis, DNA damage, chromosomal aberration, and these phenomena are called bystander effect. Bystander effect is caused by two major pathways, gap junction signaling or medium-mediated signaling. The correlation of these pathways with bystander effect, and some transmission agents of the effect were reported in many papers. But the existence of the particle number- or LET-dependency of the effect is still a matter of debate. In this experiment, we demonstrated that the particle number-dependency of bystander effect was observed in AG01522 cells exposed to carbon ion beams with LET of about 100 keV/m, and suggested the existence of the LET-dependency of this effect.