Suzuki Masao, Tsuruoka Chizuru, Uchihori Yukio, Kitamura Hisashi, Liu Cui Hua
Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
J Radiat Res. 2009 Sep;50(5):395-9. doi: 10.1269/jrr.09049. Epub 2009 Aug 13.
We studied cellular responses in normal human fibroblasts induced with low-dose (rate) or low-fluence irradiations of different radiation types, such as gamma rays, neutrons and high linear energy transfer (LET) heavy ions. The cells were pretreated with low-dose (rate) or low-fluence irradiations (approximately 1 mGy/7-8 h) of 137Cs gamma rays, 241Am-Be neutrons, helium, carbon and iron ions before irradiations with an X-ray challenging dose (1.5 Gy). Helium (LET = 2.3 keV/microm), carbon (LET = 13.3 keV/microm) and iron (LET = 200 keV/microm) ions were produced by the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. No difference in cell-killing effect, measured by a colony forming assay, was observed among the pretreatment with different radiation types. In mutation induction, which was detected in the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus to measure 6-thioguanine resistant clones, there was no difference in mutation frequency induced by the X-ray challenging dose between unpretreated and gamma-ray pretreated cells. In the case of the pretreatment of heavy ions, X-ray-induced mutation was around 1.8 times higher in helium-ion pretreated and 4.0 times higher in carbon-ion pretreated cells than in unpretreated cells (X-ray challenging dose alone). However, the mutation frequency in cells pretreated with iron ions was the same level as either unpretreated or gamma-ray pretreated cells. In contrast, it was reduced at 0.15 times in cells pretreated with neutrons when compared to unpretreated cells. The results show that cellular responses caused by the influence of hprt mutation induced in cells pretreated with low-dose-rate or low-fluence irradiations of different radiation types were radiation-quality dependent manner.
我们研究了不同辐射类型（如γ射线、中子和高线性能量转移（LET）重离子）的低剂量（率）或低通量照射诱导的正常人成纤维细胞的细胞反应。在用X射线激发剂量（1.5 Gy）照射之前，先用137Cs γ射线、241Am-Be中子、氦离子、碳离子和铁离子进行低剂量（率）或低通量照射（约1 mGy/7 - 8 h）预处理细胞。氦离子（LET = 2.3 keV/μm）、碳离子（LET = 13.3 keV/μm）和铁离子（LET = 200 keV/μm）由日本千叶的重离子医学加速器（HIMAC）产生。通过集落形成试验测量的细胞杀伤效应在不同辐射类型的预处理之间未观察到差异。在次黄嘌呤 - 鸟嘌呤磷酸核糖转移酶（hprt）基因座检测6 - 硫鸟嘌呤抗性克隆以测量突变诱导时，未预处理细胞和γ射线预处理细胞之间，X射线激发剂量诱导的突变频率没有差异。在重离子预处理的情况下，与未预处理细胞相比，氦离子预处理细胞中X射线诱导的突变高出约1.8倍，碳离子预处理细胞中高出4.0倍（仅X射线激发剂量）。然而，铁离子预处理细胞中的突变频率与未预处理细胞或γ射线预处理细胞处于相同水平。相比之下，与未预处理细胞相比，中子预处理细胞中的突变频率降低至0.15倍。结果表明，不同辐射类型的低剂量率或低通量照射预处理细胞中诱导的hprt突变影响所引起的细胞反应是以辐射质量依赖的方式。
