Dikomey E, Dahm-Daphi J, Brammer I, Martensen R, Kaina B
Institute of Biophysics and Radiobiology, University of Hamburg, Germany.
Int J Radiat Biol. 1998 Mar;73(3):269-78. doi: 10.1080/095530098142365.
To test the relationship between cell killing and non-repaired DNA strand breaks both in repair proficient and deficient cell lines.
Five of the cell lines used are repair competent (CHO, CHO K1, rat rhabdomyosarcoma R1H, mouse balb and normal human fibroblasts), while four display a reduced repair capacity (scid, xrs1, xrs5, AT). Cell survival was determined by colony formation assay. The total number of strand breaks was measured by the alkaline unwinding technique and the numbers of double-strand breaks by constant-field gel electrophoresis.
The nine cell lines showed a broad spectrum in radiosensitivity with SF2 values ranging from 0.018 to 0.58. The cell lines did not vary in the number of induced strand breaks, neither for all strand breaks nor for double-strand breaks alone. In contrast, there was a large variation in the number of non-repaired strand breaks measured 24 h after irradiation. Comparison of cell killing with the number of non-repaired breaks measured after a dose of 90 Gy showed no correlation for single-strand breaks (r2=0.29) but a fairly good correlation for double-strand breaks (r2=0.87). This correlation was found to hold both for repair proficient and deficient cell lines.
The results obtained strongly suggest that the number of non-repaired double-strand breaks measured 24h after irradiation can be used as an indicator of cellular radiosensitivity.
检测在修复能力正常和缺陷的细胞系中细胞杀伤与未修复的DNA链断裂之间的关系。
所使用的细胞系中有五个具有修复能力（中国仓鼠卵巢细胞系CHO、CHO K1、大鼠横纹肌肉瘤R1H、小鼠balb细胞系和正常人成纤维细胞），而另外四个细胞系的修复能力降低（严重联合免疫缺陷细胞系scid、xrs1、xrs5、共济失调毛细血管扩张症细胞系AT）。通过集落形成试验测定细胞存活率。采用碱性解旋技术测量链断裂的总数，通过恒定电场凝胶电泳测量双链断裂的数量。
这九个细胞系在放射敏感性方面表现出广泛的范围，其SF2值在0.018至0.58之间。这些细胞系在诱导的链断裂数量上没有差异，无论是总的链断裂还是仅双链断裂。相反，在照射后24小时测量的未修复链断裂数量存在很大差异。将细胞杀伤与90 Gy剂量后测量的未修复断裂数量进行比较，发现单链断裂无相关性（r2 = 0.29），但双链断裂有较好的相关性（r2 = 0.87）。这种相关性在修复能力正常和缺陷的细胞系中均成立。
所获得的结果强烈表明，照射后24小时测量的未修复双链断裂数量可作为细胞放射敏感性的指标。
