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Role of Chk1 and Chk2 in Ara‐C‐induced differentiation of human leukemia K562 cells
Author(s) -
Takagaki Kazuchika,
Katsuma Susumu,
Kaminishi Yoshinori,
Horio Tatsuya,
Tanaka Teruo,
Ohgi Tadaaki,
Yano Junichi
Publication year - 2005
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2005.00821.x
Subject(s) - k562 cells , biology , leukemia , chek1 , checkpoint kinase 2 , kinase , dna damage , cell culture , apoptosis , microbiology and biotechnology , biochemistry , cancer research , cell cycle , dna , cell cycle checkpoint , immunology , genetics
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 Gö6976, 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.