@article{oai:repo.qst.go.jp:00049343,
 author = {Kobayashi, Alisa and Konishi, Teruaki and Kobayashi, Alisa and Konishi, Teruaki},
 issue = {6},
 journal = {Journal of Radiation Research},
 month = {Jul},
 note = {This study aimed to determine whether the radiation induced bystander effect (RIBE) is affected by the radiation quality. To mimic the different radiation qualities of the direct action (D) / indirect action (ID) ratio, A549 cells were exposed to X-rays, with either 100 mM of the radical scavenger, thio-urea (TU+), or null (TU-). Biological responses in irradiated and bystander cells were compared at equal lethal effects of a 6% survival dose, which was estimated from the survival curves to be 8 Gy and 5 Gy for TU+ and TU-, respectively. The cyclooxygenase-2 (COX-2) expression in TU- irradiated cells increased up to 8 hrs post-irradiation, before decreasing toward 24 hrs. The concentration of prostaglandin E2 (PGE2), a primary product of COX-2, and known as a secreted inducible factor of RIBE have increased over 3-fold compared with that in the control at 8 hrs post irradiation. Conversely, COX-2 expression and PGE2 production of TU+ irradiated cells were drastically suppressed. These results show that the larger D/ID suppressed COX-2 expression and PGE2 production in irradiated cells. However, in contrast to the irradiated cells, the COX-2 expression was equally observed in the TU- and TU+ co-cultured bystander cells, which shows the highest expression levels at 24hrs post-irradiation. Taken together, these findings demonstrate that radiation quality, such as the D/ID ratio may become an important factor in the alteration of signalling pathways involved in RIBE.},
 pages = {754--759},
 title = {Radiation quality effects alteration in COX-2 pathway to trigger radiation-induced bystander response in A549 lung carcinoma cells},
 volume = {59},
 year = {2018}
}