Cell cycle and growth response of CHO cells to X-irradiation:: Threshold-free repair at low doses
Cell cycle and growth response of CHO cells to X-irradiation:: Threshold-free repair at low doses
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DOI：
10.1016/s0360-3016(01)01455-9
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发表时间：
2001-05-01
影响因子：
7
通讯作者：
Röttinger, EM
中科院分区：
文献类型：
--
作者：
Bartkowiak, D;Högner, S;Röttinger, EM
目的：为验证低剂量X射线照射诱导DNA损伤修复（IR）和辐射超敏感性（HRS）的阈值假说，方法和材料：用0.2 ~ 8戈伊剂量X射线照射指数生长期的中国仓鼠卵巢细胞（CHO），通过常规集落形成实验和流式细胞术计数建立存活数据。结果：克隆形成数据与HRS一致，但统计学意义不显著。群体计数提供了高度可重复的存活曲线，其与线性二次（LQ）模型完全雅阁。主要的细胞周期反应是G2 M期和S期晚期的剂量依赖性延迟。结论：没有证据表明X射线照射CHO细胞的IR阈值和低剂量HRS。这表明DNA损伤修复活性在S期组成性表达，并在S期晚期和G2以剂量依赖性和无阈值的方式额外诱导，由此产生的存活率由LQ模型精确描述。(C)2001 Elsevier Science Inc.
Purpose: To test the hypothesis of a threshold for induced repair of DNA damage (IR) and, secondarily, of hyperradiosensitivity (HRS) to low-dose X-irradiation,Methods and Materials: Exponentially growing Chinese hamster ovary cells (CHO) were X-irradiated with doses from 0.2 to 8 Gy, Survival data were established by conventional colony-forming assay and flow-cytometric population counting. The early cell cycle response to radiation was studied based on DNA-profiles and bromodeoxyuridine pulse-labeling experiments.Results: Colony-forming data were consistent with HRS, However, these data were of low statistic significance. Population counting provided highly reproducible survival curves that were in perfect accord with the linear-quadratic (LQ) model. The dominant cell cycle reaction was a dose-dependent delay of G2 M and late S-phase,Conclusion: There was no evidence for a threshold of IR and for low-dose HRS in X-irradiated CHO cells. It is suggested that DNA damage repair activity is constitutively expressed during S-phase and is additionally induced in a dose-dependent and threshold-free manner in late S-phase and G2, The resulting survival is precisely described by the LQ model. (C) 2001 Elsevier Science Inc.