King Faisal Specialist Hospital & Research Centre , Riyadh , Saudi Arabia.
Int J Radiat Biol. 2014 Jan;90(1):53-9. doi: 10.3109/09553002.2014.859764.
To test the hypothesis that differences in DNA double-strand breaks (DSB) repair fidelity underlies differences in radiosensitivity.
A primary fibroblast culture (C42) derived from a pediatric cancer patient treated with reduced radiation doses consequent to a family history of radiosensitivity reminiscent of chromosomal fragility syndrome, was compared to a normal control (C29). DNA DSB rejoining and repair fidelity were studied by Southern blotting and hybridization to specific fragments: Alu repetitive sequence representing the overall DSB rejoining capacity in the genome and a 3.2 Mbp NotI restriction fragment on chromosome 21 for DSB repair fidelity.
Although both assays showed statistically significant difference (p ≤ 0.05) between the two cell strains in residual misrepaired (un-or mis-rejoined) DSB (24 h after 30 or 80 Gy), the residual damage was lower in the Alu enriched genome assay compared to NotI assay (0.01-0.07 and 0.10-0.37, respectively).
These results suggest that, in comparison to classic DSB repair experiment, an assay of measuring DNA DSB repair fidelity can provide better resolution and a more accurate estimate of misrepair of radiation-induced DNA damage, which underlies genomic instability and increased radiosensitivity.
验证这样一个假设，即 DNA 双链断裂（DSB）修复保真度的差异是导致放射敏感性差异的基础。
我们比较了一个源自儿科癌症患者的原代成纤维细胞培养物（C42）与正常对照（C29），该患者因家族史中存在类似于染色体脆弱综合征的放射敏感性，因此接受了降低剂量的放射治疗。通过 Southern 印迹杂交和与特定片段的杂交，研究了 DNA DSB 重连和修复保真度：Alu 重复序列代表基因组中总体 DSB 重连能力，以及染色体 21 上的 3.2 Mbp NotI 限制片段用于 DSB 修复保真度。
尽管两种检测方法均显示两种细胞株之间在残留错误修复（未修复或错误连接）DSB 方面存在统计学显著差异（p ≤ 0.05）（在 30 或 80 Gy 后 24 小时），但在 Alu 富集基因组检测中残留损伤低于 NotI 检测（分别为 0.01-0.07 和 0.10-0.37）。
与经典 DSB 修复实验相比，这些结果表明，测量 DNA DSB 修复保真度的检测可以提供更好的分辨率，并更准确地估计放射诱导的 DNA 损伤的错误修复，这是基因组不稳定性和放射敏感性增加的基础。
