Role of Chk1 and Chk2 in Ara-C-induced differentiation of human leukemia K562 cells
Role of Chk1 and Chk2 in Ara-C-induced differentiation of human leukemia K562 cells
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DOI：
10.1111/j.1365-2443.2005.00821.x
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发表时间：
2005-02-01
期刊：
影响因子：
2.1
通讯作者：
Yano, J
中科院分区：
文献类型：
--
作者：
Takagaki, K;Katsuma, S;Yano, J
人慢性髓性白血病K562细胞对抗代谢物阿糖胞苷（Ara-C）具有相对抗性，并且当用Ara-C处理时，它们分化成红细胞而不经历凋亡。本研究探讨了阿糖胞苷诱导K562细胞分化的机制。我们首先观察到，Ara-C诱导的这些细胞的分化完全抑制的放射增敏剂咖啡因，ATM和ATR蛋白激酶的抑制剂。我们接下来发现，Ara-C激活细胞中的Chk 1和Chk 2，并且Chk 1的激活几乎完全被咖啡因抑制，而不是Chk 2。蛋白酶体介导的Cdc 25 A的降解和Cdc 25 C的磷酸化诱导Ara-C处理，推测是由于Chk 2和Chk 1的激活，分别。为了直接观察检查点激酶激活在Ara-C诱导分化中的作用，我们用Chk 1特异性抑制剂Go 6976抑制Chk 1或Chk 2，通过产生稳定过表达Chk 2的显性阴性形式的细胞系，或通过siRNA介导的Chk 1或Chk 2基因敲低。结果提示，阿糖胞苷诱导K562细胞向红系分化依赖于Chk 1和Chk 2两条途径。
Human chronic myelogenous leukemia K562 cells are relatively resistant to the anti-metabolite cytosine arabinoside (Ara-C) and, when treated with Ara-C, they differentiate into erythrocytes without undergoing apoptosis. In this study we investigated the mechanism by which Ara-C induces K562 cells to differentiate. We first observed that Ara-C-induced differentiation of these cells is completely inhibited by the radiosensitizing agent caffeine, an inhibitor of ATM and ATR protein kinases. We next found that Ara-C activates Chk1 and Chk2 in the cells, and that the activation of Chk1, but not of Chk2, was almost completely inhibited by caffeine. Proteasome-mediated degradation of Cdc25A and phosphorylation of Cdc25C were induced by Ara-C treatment, presumably due to the activation of Chk2 and Chk1, respectively. To directly observe the effects of checkpoint kinase activation in Ara-C-induced differentiation, we suppressed Chk1 or Chk2 with the Chk1-specific inhibitor Go6976, by generating cell lines stably over-expressing dominant-negative forms of Chk2, or by siRNA-mediated knock-down of the Chk1 or the Chk2 gene. The results suggest that Ara-C-induced erythroid differentiation of K562 cells depends on both Chk1 and Chk2 pathways.