Distinct roles for p53 transactivation and repression in preventing UCN-01-mediated abrogation of DNA damage-induced arrest at S and G2 cell cycle checkpoints
Distinct roles for p53 transactivation and repression in preventing UCN-01-mediated abrogation of DNA damage-induced arrest at S and G2 cell cycle checkpoints
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DOI：
10.1038/sj.onc.1208451
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发表时间：
2005-05-26
期刊：
影响因子：
8
通讯作者：
Eastman, A
中科院分区：
文献类型：
--
作者：
Levesque, AA;Kohn, EA;Eastman, A
拓扑异构酶 I 抑制剂 SN38 以不依赖 p53 的方式主要在细胞周期的 S 或 G(2) 期阻止细胞周期进展。 Chk1 抑制剂 7-羟基星孢菌素 (UCN-01) 可优先克服 p53 突变细胞中的 S 和 G(2) 阻滞，驱动细胞进行致命的有丝分裂，从而增强细胞毒性。本文研究了 p53 维持 S 和 G(2) 停滞的机制。通过与 SN38 孵育 24 小时，将 p53 野生型 MCF10A 细胞阻滞在 S 期。随后与 UCN-01 的孵育未能消除逮捕。为了检查 p53 的影响，开发了 MCF10A 细胞，该细胞表达 p53 四聚化结构域以抑制内源性 p53 功能。这些细胞在 SN38 介导的 p21(WAF1) 诱导中减弱，UCN-01 诱导 S，但不诱导 G(2) 进展。相比之下，表达短发夹RNA以消除p53表达的MCF10A细胞在UCN-01的作用下经历了S和G(2)期进展。 G(2)进展的差异归因于p53介导的基因抑制；表达四聚化结构域的 MCF10A 细胞保留了 p53 蛋白并抑制细胞周期蛋白 B 和 Chk1，而消除 p53 的细胞则不抑制这些蛋白。因此，抑制 p53 激活子功能可以消除 S 期，而需要额外抑制 p53 阻遏物功能才能消除 G(2) 阻滞。这些研究为这种治疗策略如何选择性地靶向肿瘤细胞提供了机制解释。
The topoisomerase I inhibitor SN38 arrests cell cycle progression primarilyin S or G(2) phases of the cell cycle in a p53-independent manner. The Chk1 inhibitor, 7-hydroxystaurosporine (UCN-01), overcomes both S and G(2) arrest preferentiallyin cells mutated for p53, driving cells through a lethal mitosis and thereby enhancing cytotoxicity. The mechanism by which p53 maintains S and G(2) arrest was investigated here. The p53 wild-type MCF10A cells were arrested in S phase by incubation with SN38 for 24 h. Subsequent incubation with UCN-01 failed to abrogate arrest. To examine the impact of p53, MCF10A cells were developed, which express the tetramerization domain of p53 to inhibit endogenous p53 function. These cells were attenuated in SN38-mediated induction of p21(WAF1), and UCN-01 induced S, but not G(2) progression. In contrast, MCF10A cells expressing short hairpin RNA to ablate p53 expression underwent both S and G(2) phase progression with UCN-01. The difference in G(2) progression was attributed to p53-mediated gene repression; the MCF10A cells expressing the tetramerization domain retained p53 protein and repressed both cyclin B and Chk1, while cells ablated for p53 did not repress these proteins. Hence, inhibition of p53 activator function permits S phase abrogation, while additional inhibition of p53 repressor function is required for abrogation of G(2) arrest. These studies provide a mechanistic explanation for how this therapeutic strategy can selectively target tumor cells.