Kinetics and dose-response of residual 53BP1/γ-H2AX foci:: Co-localization, relationship with DSB repair and clonogenic survival
Kinetics and dose-response of residual 53BP1/γ-H2AX foci:: Co-localization, relationship with DSB repair and clonogenic survival
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DOI：
10.1080/09553000601170469
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发表时间：
2007-01-01
影响因子：
2.6
通讯作者：
Belyaev, I. Y.
中科院分区：
文献类型：
--
作者：
Markova, E.;Schultz, N.;Belyaev, I. Y.
目的：最近的研究表明，与辐射诱导的DNA双链断裂(DSB)共定位的磷酸化组蛋白2A家族成员X(Gamma-H2AX)和抑癌基因P53结合蛋白1(53BP1)产生的一些病灶在照射后较长时间内仍留在细胞内，表明细胞的放射敏感性与残留的病灶可能存在相关性。在这项研究中，我们研究了辐射诱导的53BP1/伽马-H_2AX病灶形成的剂量效应和动力学与它们的共定位、DSB修复和细胞存活的关系。材料和方法：分别用克隆形成法、脉冲场凝胶电泳法(PFGE)和激光共聚焦显微镜分析正常人成纤维细胞(VH-10)和癌细胞系(HeLa)的细胞存活、DSB和病灶。结果：我们发现，即使在剂量降至1cGy时，也能观察到具有统计学意义的53BP1病灶的诱发。虽然病灶的数量随着照射后时间的延长而不断减少，但在照射后约4小时的时间窗口内，每个细胞的病灶归一化面积并没有变化。伽马-H_2AX和53BP1焦点的共定位显示出依赖于剂量和照射后的时间。由于~(53)BP1/γ-H_2AX焦点的剂量效应可能依赖于照射后的时间和细胞周期的持续时间，因此在辐射敏感性和病灶形成之间没有明确的相关性。我们发现，照射后24小时内病灶消失的动力学与DSB修复的动力学并不一致。结论：这些数据表明，用于通过对残留病灶进行评分来评估治疗相关低剂量(例如，~lt；3GY)对增殖细胞的放射敏感性的照射后时间应受到细胞周期的持续时间的限制，并且不可能直接比较DSB修复和DSB共定位病灶消失的动力学。因此，应谨慎地从DSB修复的角度来解释病灶计数的结果。
Purpose: Recent studies revealed that some foci produced by phosphorylated histone 2A family member X (gamma-H2AX) and tumor suppressor p53 binding protein 1 (53BP1) that co-localize with radiation-induced DNA double-strand breaks (DSB) remain in cells at relatively long times after irradiation and indicated a possible correlation between cellular radiosensitivity and residual foci. In this study, we investigated dose-responses and kinetics for radiation-induced 53BP1/gamma-H2AX foci formation in relation to their co-localization, DSB repair and cell survival.Materials and methods: Cell survival, DSB and foci were analyzed by clonogenic assay, pulsed field gel electrophoresis (PFGE), and confocal laser microscopy, respectively, in normal human fibroblasts (VH-10) and in a cancer cell line (HeLa). Computer analysis was used to determine both the number and the area of foci.Results: We show that even at doses down to 1 cGy a statistically significant induction of 53BP1 foci is observed. While the number of foci was found to constantly decrease with post-irradiation time, the per-cell normalized area of foci does not change within a time window of approximately 4 h post-irradiation. Co-localization of gamma-H2AX and 53BP1 foci is shown to depend on dose and post-irradiation time. No clear correlations were established between radiosensitivity and foci formation because the dose response for 53BP1/gamma-H2AX foci may depend on time after irradiation and duration of the cell cycle. We show that the kinetics of foci disappearance within 24 h post-irradiation do not coincide with those of DSB repair.Conclusions: The data suggest that the post-irradiation time used for estimation of radiosensitivity at therapeutically relevant low doses (e.g., < 3 Gy) in proliferating cells by scoring residual foci should be limited by the duration of the cell cycle, and ;that direct comparison of the kinetics of DSB repair and disappearance of DSB-co-localizing foci is not possible. Therefore, results obtained from the counting of foci should be interpreted with caution in terms of DSB repair.