@misc{oai:repo.qst.go.jp:00070117,
 author = {Suzuki, Masao and Tsuruoka, Chizuru and Yasuda, Nakahiro and Kitamura, Hisashi and Konishi, Teruaki and Furusawa, Yoshiya and 鈴木 雅雄 and 鶴岡 千鶴 and 安田 仲宏 and 北村 尚 and 小西 輝昭 and 古澤 佳也},
 month = {May},
 note = {Purpose
There are numerous reports concerning bystander effects after exposure to low fluences of alpha particles. However, only a limited number of studies have examined bystander effects after exposure to low fluences of ion species heavier than helium. In this study we investigated p53-dependent bystander lethal effect in tumor cell lines irradiated with low-fluence beams of low energy carbon ions. 
\nMethods
One normal human and one tumor cells with wild-type p53 and two tumor cell lines with mutated-type p53 were used. Cell-killing effect was detected using a colony formation assay as a reproductive cell death. Irradiation dishes were constructed by drilling 6.5mm holes in the center of 35mm-diameter tissue culture dishes and then attaching a 2.5µm-thick Mylar film over the bottom of the hole to provide a window for low-energy carbon-ion beams. Cells were inoculated onto the Mylar film and then irradiated with 6MeV/n carbon ions at a fluence of 1.5 x 105 particles/cm2. The beam was generated by the Medium Energy Beam Course at the Heavy Ion Medical Accelerator in Chiba (HIMAC). Cells were exposed using 4 different protocols; (1) Cells were irradiated with all of the cells on the Mylar film; (2) Cells were irradiated with half of the cell population on the Mylar film; (3) Irradiated cells and unirradiated control cells were pooled in a 1:1 ratio and plated as a single culture; and (4) Cells were irradiated and treated with a specific inhibitor of gap-junction mediated cell-cell communication (40µM lindane). 
\nResults
Cell-killing effect in human normal and tumor cells harboring wild-type p53 showed that the surviving fraction of the irradiated group (2) was almost the same as the group (1). In addition, a similar level of survival was seen in the group (4) and the group (3). Pooling the irradiated and unirradiated cells after irradiation probably blocks cell-cell communication because there is insufficient time for gap junctions to form and transmit any signals present in the irradiated cells immediately after irradiation. On the other hand, there was no change in surviving fraction among the group (2), (3) and (4) in p53-mutated tumor cells.
\nConclusions
There is evidence that p53-related bystander lethal effect is an important role of carbon-ion induced cell-killing effect., PTCOG49},
 title = {P53-dependent bystander lethal effect induced by the low-fluence irradiation of carbon ions.},
 year = {2010}
}