一般注記There has been a recent upsurge of interest in radiation-induced adaptive response and bystander effect, which are specific modes in stress response to low-dose/low-dose rate radiation. Previously we reported that the accumulation of inducible nitric oxide(NO)synthase(iNOS)was induced only in human glioblastoma mutant(m)p53 cells by acute irradiation with X-rays, suggesting a suppression of iNOS induction after acute irradiation with X-rays in wild-type(wt)p53 cells. NO secreted from the irradiated mp53 cells induced the accumulation of p53 in unirradiated wtp53 ce11s. The radiosensitivity of wtp53 cells was reduced by exposure to the conditioned medium from irradiated mp53 cells, suggesting that NO is an initiator of radiation-induced bystander effects. Recently, we found that the accumulation of iNOS in wtp53 cells was induced by chronic irradiation with gamma rays followed by acute irradiation with X-rays, but not by each one,resulting in an increase in nitrite concentrations of medium. it is suggested that the accumulation of iNOS may be due to the depression of acute irradiation-induced p53 functions by pre-chronic irradiation. We found that the radiosensitivity of wtp53 cells against acute irradiation with X-rays was reduced after chronic irradiation with gamma rays. This reduction of radiosensitivity of wtp53 cells is just radiationinduced adaptive response, suggesting that NO-mediated bystander effect may considerably contribute to adaptive response induced by radiation.
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連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）