Etoposide-induced apoptosis in human HL-60 cells is associated with intracellular acidification.
Etoposide-induced apoptosis in human HL-60 cells is associated with intracellular acidification.
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发表时间：
1993-05
期刊：
影响因子：
11.2
通讯作者：
M. Barry;J. Reynolds;A. Eastman
中科院分区：
文献类型：
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作者：
M. Barry;J. Reynolds;A. Eastman
细胞凋亡是以基因组DNA的核小体间消化为特征的细胞死亡途径。这种DNA消化可以通过生理刺激和许多抗癌剂的细胞毒性治疗来诱导。这种消化通常被认为是由Ca 2 +/Mg（2+）依赖性核酸内切酶介导的，该核酸内切酶通过细胞内Ca 2+的增加而被激活。然而，我们认为，一种替代的核酸内切酶，DNA酶II，可能是一个更可能的候选人。在这些研究中，通过与拓扑异构酶II抑制剂依托泊苷孵育30分钟诱导人HL-60细胞凋亡。细胞凋亡特征的DNA消化在除去依托泊苷后3小时内开始。同时观察细胞凋亡的形态学指标。此时只有约20%的细胞发生凋亡;这些细胞在依托泊苷处理时似乎处于S期。剩余的细胞进展到G2期，并在那里停滞至少48小时。通过流式细胞术测量单个细胞中的细胞内Ca 2+和pH。没有观察到细胞内Ca 2+的变化，但在约15%的细胞中发生了高达1个pH单位的酸化，并与DNA消化出现的时间过程相关。根据细胞内pH值对细胞进行分选，只有酸性细胞显示出凋亡的形态和DNA消化特征。这些结果表明，DNA酶II参与细胞凋亡的DNA消化，并建议作为调节细胞凋亡的pH稳态的机制。
Apoptosis is a pathway of cell death characterized by internucleosomal digestion of genomic DNA. Such DNA digestion can be induced by both physiological stimuli and cytotoxic treatment with many anticancer agents. This digestion has generally been considered to be mediated by a Ca2+/Mg(2+)-dependent endonuclease that is activated by increases in intracellular Ca2+. However, we suggest that an alternate endonuclease, DNase II, may be a more likely candidate. In these studies, apoptosis was induced in human HL-60 cells by a 30-min incubation with the topoisomerase II inhibitor etoposide. DNA digestion characteristic of apoptosis began within 3 h of removal of etoposide. Morphological indication of apoptosis was observed concurrently. Only about 20% of the cells underwent apoptosis at this time; these appeared to be cells in S phase at the time of etoposide treatment. The remainder of the cells progressed to the G2 phase and arrested there for at least 48 h. Intracellular Ca2+ and pH were measured in individual cells by flow cytometry. No changes in intracellular Ca2+ were observed, but an acidification of up to 1 pH unit occurred in about 15% of the cells and correlated with the time course of appearance of DNA digestion. Cells were sorted on the basis of intracellular pH and only the acidic cells showed the morphology and DNA digestion characteristic of apoptosis. These results demonstrate the involvement of DNase II in apoptotic DNA digestion and suggest mechanisms of pH homeostasis as regulators of apoptosis.