Boyd M, Livingstone A, Wilson L E, Marshall E M, McCluskey A G, Mairs R J, Wheldon T E
Department of Radiation Oncology, Glasgow University, UK.
Int J Radiat Biol. 2000 Feb;76(2):169-76. doi: 10.1080/095530000138826.
The study was designed to determine the dose-response relationship for radiation induction of mutations at mini- and microsatellite loci in human somatic cells. Mutations induced by graded doses of gamma-irradiation were quantified by screening clones derived from single irradiated cells for micro- and minisatellite alterations following irradiation with 1, 2 or 3 Gy.
After irradiation, the moderately radioresistant glioma cell line UVW was seeded at low density into Petri dishes to allow formation of discrete colonies, 100 of which were examined at each dose. All the cells within a colony were presumed to have arisen from a single irradiated cell. Radiation-induced microsatellite alterations were determined at 16 different loci, by PCR amplification and visualization on polyacrylamide gels. Minisatellite alterations were identified at four different minisatellite loci by restriction enzyme digestion and Southern blotting.
A dose-response curve for mutation frequency was obtained by analysis of 100 clones, yielding a minisatellite mutation rate of 5.5x10(-3) mutations/locus/Gy/cell and a microsatellite mutation rate of 8.75x10(-4) mutations/locus/ Gy/cell. At microsatellite loci, alterations were predominantly simple loss or gain of repeat units and loss of heterozygosity (LOH). The mutations in minisatellite loci resulted predominantly in LOH and variation in repeat number. The background instability at each locus was determined by analysis of non-irradiated clones. Only 2% and 1% of the micro-and minisatellite loci respectively showed altered bands.
This is the first report of a dose-response relationship for radiation-induced micro- and minisatellite mutations in human somatic cells. Described is a sensitive method for analysis of low-dose radiation mutagenesis in somatic cells that may prove to be a useful tool for radiation protection and dosimetry.
本研究旨在确定人类体细胞中，小卫星和微卫星位点辐射诱导突变的剂量反应关系。通过筛选来自单个受辐照细胞的克隆，对1、2或3 Gy照射后的小卫星和微卫星改变进行定量，以量化不同剂量γ射线照射诱导的突变。
照射后，将中度耐辐射的胶质瘤细胞系UVW低密度接种到培养皿中，以形成离散的集落，每个剂量检查100个集落。假定集落内的所有细胞均来自单个受辐照细胞。通过PCR扩增并在聚丙烯酰胺凝胶上可视化，在16个不同位点测定辐射诱导的微卫星改变。通过限制性内切酶消化和Southern印迹法，在四个不同的小卫星位点鉴定小卫星改变。
通过对100个克隆的分析获得了突变频率的剂量反应曲线，小卫星突变率为5.5x10(-3)突变/位点/Gy/细胞，微卫星突变率为8.75x10(-4)突变/位点/Gy/细胞。在微卫星位点，改变主要是重复单元的简单缺失或增加以及杂合性缺失（LOH）。小卫星位点的突变主要导致LOH和重复数目的变化。通过对未辐照克隆的分析确定每个位点的背景不稳定性。分别只有2%和1%的微卫星和小卫星位点显示出条带改变。
这是关于人类体细胞中辐射诱导的微卫星和小卫星突变剂量反应关系的首次报告。描述了一种用于分析体细胞中低剂量辐射诱变的灵敏方法，该方法可能被证明是辐射防护和剂量测定的有用工具。
