Spontaneous premature chromosome condensation and mitotic catastrophe following irradiation of HeLa S3 cells
Spontaneous premature chromosome condensation and mitotic catastrophe following irradiation of HeLa S3 cells
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DOI：
10.1080/095530097143185
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发表时间：
1997-10-01
影响因子：
2.6
通讯作者：
Mackey, MA
中科院分区：
文献类型：
--
作者：
Ianzini, F;Mackey, MA
目的：为研究电离辐射对人肿瘤细胞G（2）/M检查点控制丧失导致有丝分裂灾难的机制，材料和方法：用5、10和20戈伊X射线照射人HeLa S3细胞。细胞周期的进展和细胞周期蛋白B1的水平进行了测量，使用双变量流式细胞术技术作为照射后的时间的函数。作为有丝分裂灾难的指标，使用显微镜分析了自发性过早染色体凝聚（SPCC）和呈现核碎裂的细胞的外观。免疫沉淀和凝胶电泳分析测定细胞周期蛋白B1依赖性激酶活性。结果：HeLa细胞经X射线照射后，细胞周期的S期和G（2）期延迟，随后出现SPCC和核碎裂，均提示有丝分裂灾难。明显经历有丝分裂灾难的细胞外观动力学（即表现出核碎裂的细胞比例）与剂量依赖性辐射诱导的分裂延迟无关，而碎裂程度（表示为每个碎裂细胞的核碎片数量）确实随剂量增加。还观察到晚期S/G（2）细胞中细胞周期蛋白BI水平升高5倍，这与观察到的细胞周期晚期延迟在时间上相关。随着细胞周期蛋白水平的升高，细胞周期蛋白B1相关的组蛋白H1激酶活性也表现出类似的增加;这些激酶活性的增加发生在表现出核碎裂的细胞比例增加之前。在人类细胞中，细胞周期蛋白B1基因表达发生在晚期3和G（2）期，因此在该蛋白质中观察到的增加可能是由于细胞在这些阶段中花费的时间增加，这是由于辐射暴露引起的细胞周期延迟的结果。在这些条件下，细胞周期蛋白B1的过度积累可能会稀释weel或其他抑制途径的有丝分裂抑制作用。因此，这项研究提出了一个可能的机制，G（2）/M检查点废除后，电离辐射，这可能仅仅取决于与干扰细胞周期进程的影响。
Purpose: To study the mechanisms underlying the loss of G(2)/M checkpoint control which leads to mitotic catastrophe in human tumour cells following exposure to ionizing radiation.Materials and methods: Asynchronous HeLa S3 cells were irradiated with doses of 5, 10 and 20 Gy X-rays. Cell-cycle progression and cyclin B1 levels were measured using bivariate flow-cytometric techniques as a function of time after irradiation. As indicators of mitotic catastrophe, the appearance of spontaneous premature chromosome condensation (SPCC) and cells presenting nuclear fragmentation were analysed using microscopy. Cyclin B1-dependent kinase activity was determined in immunoprecipitates and analysed using gel electrophoresis.Results: After X-irradiation of HeLa cells, delays in late S and G(2) phases of the cell cycle were followed by SPCC and nuclear fragmentation, both indicative of mitotic catastrophe. The kinetics of appearance of cells that had apparently undergone mitotic catastrophe (i.e. the fraction of cells exhibiting nuclear fragmentation) was independent of the dose-dependent radiation-induced division delay, while the extent of fragmentation (expressed as the number of nuclear fragments per fragmented cell) did increase with dose. Also observed was a 5-fold elevation of cyclin BI levels in late S/G(2) cells, which correlated temporally with the observed delays late in the cell cycle. Following the appearance of elevated cyclin levels, cyclin B1-associated histone H1 kinase activity showed similar increases; these increases in kinase activity occurred prior to increases in the fraction of cells exhibiting nuclear fragmentation.Conclusions: In human cells, cyclin B1 gene expression occurs in late 3 and G(2) phases, and thus the increase observed in this protein may be due to the increased time spent by cells in these phases as a result of cell-cycle delays caused by the radiation exposure. It is possible that, under these conditions, over accumulation of cyclin B1 dilutes the mitosis-inhibitory action of the weel or other inhibitory pathways. Thus, this study presents a possible mechanism for G(2)/M checkpoint abrogation following ionizing radiation which may depend solely on effects associated with perturbed cell-cycle progression.