Chk1 is essential for tumor cell viability following activation of the replication checkpoint

被引:101
作者
Cho, SH [1 ]
Toouli, CD [1 ]
Fujii, GH [1 ]
Crain, C [1 ]
Parry, D [1 ]
机构
[1] DNAX Res Inst Mol & Cellular Biol Inc, Dept Discovery Res, Palo Alto, CA 94304 USA
关键词
Chk1; p53; Chk2; replication checkpoint; cell cycle; apoptosis; DNA damage;
D O I
10.4161/cc.4.1.1299
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
Chk1 ( checkpoint kinase 1) is an evolutionarily conserved serine/threonine kinase involved in DNA damage responses. Originally identified as a kinase regulating the G(2)/ M transition checkpoint, its role has broadened to include the S-phase checkpoint response and essential functions in early embryonic development. In this manuscript we investigated the potential of chemo-sensitization via ablation of Chk1 in cells treated with anti-metabolite cancer drugs, hydroxyurea (HU) and cytosine arabinoside (ara-C). Exposure to these replication interfering drugs in cells carrying Chk1 targeted siRNA provoked markedly increased rates of apoptosis. Although cell death was accompanied by an increase in p53 and activation of Chk2, the increased susceptibility to apoptosis was not dependent on p53 or Chk2. Additionally, we found that cells with reduced Chk1 expression displayed increased gamma-H2A. X expression, a marker for damaged DNA, and phosphorylated 32kDa subunit of replication protein A (RPA). Thus, Chk1 may play an essential role in maintaining DNA integrity during the replication block. Significantly, normal cells such as WS1 did not exhibit increased DNA damage or subsequent increases in apoptosis following replication stress, in the absence of Chk1. Thus, the essential role Chk1 plays in maintaining viability during the replication block in cancer cell lines can be exploited to sensitize cancer cells when abrogation of Chk1 is combined with DNA anti-metabolite chemotherapeutic drugs. Taken together, these data suggest that inhibition of Chk1 in combination with DNA anti-metabolite chemotherapy is a viable therapeutic strategy.
引用
收藏
页码:131 / 139
页数:9
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