DNA损伤修复能力对辐射适应性反应的影响

Role of DNA damage repair capacity in radiation induced adaptive response

采用野生型的中国仓鼠卵母细胞(CHO-9)及其DNA损伤修复缺陷型细胞:EM-C11(DNA单链断裂修复缺陷)和XR-C1(DNA双链断裂修复缺陷),首先进行低剂量(0.016Gy或0.08Gy)的初始照射,间隔4h或7h后再进行高剂量(1Gy)的攻击照射,然后检测细胞微核形成率和克隆形成率的变化。结果显示:当初始剂量为0.08Gy,间隔4h后再施以1Gy的攻击照射时,三株细胞只有野生型的CHO-9有辐射适应性反应产生;但当间隔时间延长到7h时,CHO-9和EM-C11均产生了辐射适应性反应。当把初始照射剂量降低为0.016Gy,间隔4h再施以1Gy的攻击照射时,三株细胞均产生了辐射适应性反应。表明辐射适应性反应不仅与初始照射剂量及间隔时间有关,还与DNA损伤修复密切相关。

This work was to explore γ-ray induced radioadaptive response （RAR） in Chinese hamster ovary （CHO） cell lines of different DNA damage repair capacities. CHO-9 cells and the two repair-deficient strains, EM-C11 （DNA single strand break repair deficient） and XR-C1 （DNA double strand break repair deficient）, were irradiated with a priming dose of 0.08 Gy or 0.016 Gy. After 4 or 7 hours, they were irradiated again with a challenging dose of 1 Gy. The micronucleus induction and plating efficiency of the ceils were assayed. Under 0.08 Gy priming dose and 4-h interval, just the CHO-9 cells showed RAR, while with the 7-h interval the CHO-9 and EM-Cll showed RAR, but XR-C1 did not. When the cells were pretreated with a lower priming dose of 0.016 Gy in a 4-h time interval, all the three cell lines showed RAR to subsequent 1 Gy irradiation. It can be concluded that RAR is not only related to the priming dose and time interval, but also has close dependence on the ability of DNA damage repair.