Search

In radiation cancer therapy, heavy ion will be penetrating the surface of the body to the targeted cancer region, which results various LETs of ions exposed in the patient’s body. Bystander effect of different LETs as well as radiation quality should be a taken into concern for radiation risks. In this study our aim is to evaluate LET dependence of bystander response focused on cyclooxygenase-2 (COX-2) as one of the mediator for bystander effect. For this fiscal year, we obtained survival curves for two LETs (13 keV /µm and 70 keV/μm) of 290 MeV/n carbon ion beam to confirm the induction of cell inactivation. Secondly, we measured the induction of COX-2 in both target and bystander cells by western blot analysis. As a result, COX-2 protein expression showed a gradual increase to 8 hrs post irradiation only with 70 keV/µm and not with 13 keV/µm. COX-2 in irradiated cells were 1.6 folds compared to the control. As for the bystander cells, we found that COX-2 increased only in the bystander cells co-cultured with the cells irradiated with LET 70 keV/µm, which was 1.4 folds compared to the controls. We have irradiated various doses with above two LETs and collected proteins. The COX-2 protein expression in both irradiated and bystander cells are currently under analysis, and the results will be reported in near future.

本研究ではマイクロビーム照射法を用いることで、ギャップジャンクションを介した細胞間応答を含めた照射細胞から非照射細胞へのバイスタンダー効果および非照射細胞から照射細胞への影響をがん細胞と正常細胞の共培養条件で評価した。