Abrogation of the S phase DNA damage checkpoint results in S phase progression or premature mitosis depending on the concentration of 7-hydroxystaurosporine and the kinetics of Cdc25C activation
Abrogation of the S phase DNA damage checkpoint results in S phase progression or premature mitosis depending on the concentration of 7-hydroxystaurosporine and the kinetics of Cdc25C activation
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DOI：
10.1074/jbc.m202040200
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发表时间：
2002-07-19
影响因子：
4.8
通讯作者：
Eastman, A
中科院分区：
文献类型：
--
作者：
Kohn, EA;Ruth, ND;Eastman, A
DNA损伤导致细胞周期停滞在G（1），S或G（2），以防止受损DNA的复制或防止异常的有丝分裂。G（1）阻滞需要p53肿瘤抑制因子，然而拓扑异构酶I抑制剂SN 38在G（1）检查点之后诱导p53，使得细胞仅阻滞在S或G（2）。因此，SN 38有助于比较p53野生型和突变型细胞在Abrogate S和G（2）阻滞药物（如7-羟基星孢菌素（UCN-01））的疗效方面。UCN-01在p53突变乳腺肿瘤细胞系MDA-MB-231中消除了S和G（2）阻滞，但在p53野生型乳腺细胞系MCF 10a中没有。p53野生型细胞对UCN-01的耐药性与细胞周期蛋白A和B的抑制相关。在p53突变细胞中，低浓度的UCN-01导致S期细胞在经历有丝分裂和死亡之前进展到G（2），而高浓度的UCN-01导致S期细胞的快速过早有丝分裂和死亡。UCN-01抑制Chk 1/2，Chk 1/2应激活有丝分裂诱导磷酸酶Cdc 25 C，但在低浓度UCN-01诱导的S期进展期间，该磷酸酶保持无活性，这可能是因为Cdc 25 C也被组成性激酶GTAK 1抑制。高浓度的UCN-01引起Cdc 25 C的快速活化，这归因于C-TAK 1以及Chk 1/2的抑制。因此，UCN-01具有多种效应，这取决于浓度和细胞表型，在研究检查点调控机制时必须考虑这些效应。
DNA damage causes cell cycle arrest in G(1), S, or G(2) to prevent replication on damaged DNA or to prevent aberrant mitosis. The G(1) arrest requires the p53 tumor suppressor, yet the topoisomerase I inhibitor SN38 induces p53 after the G(1) checkpoint such that the cells only arrest in S or G(2). Hence, SN38 facilitates comparison of p53 wild-type and mutant cells with regard to the efficacy of drugs such as 7-hydroxystaurosporine (UCN-01) that Abrogate S and G(2) arrest. UCN-01 abrogated S and G(2) arrest in the p53 mutant breast tumor cell line MDA-MB-231 but not in the p53 wild-type breast line, MCF10a. This resistance to UCN-01 in the p53 wild-type cells correlated with suppression of cyclins A and B. In the p53 mutant cells, low concentrations of UCN-01 caused S phase cells to progress to G(2) before undergoing mitosis and death, whereas high concentrations caused rapid premature mitosis and death of S phase cells. UCN-01 inhibits Chk1/2, which should activate the mitosis-inducing phosphatase Cdc25C, yet this phosphatase remained inactive during S phase progression induced by low concentrations of UCN-01, probably because Cdc25C is also inhibited by the constitutive kinase, G TAK1. High concentrations of UCN-01 caused rapid activation of Cdc25C, which is attributed to inhibition of C-TAK1, as well as Chk1/2. Hence, UCN-01 has multiple effects depending on concentration and cell phenotype that must be considered when investigating mechanisms of checkpoint regulation.