CHK1 Inhibition Synergizes with Gemcitabine Initially by Destabilizing the DNA Replication Apparatus
CHK1 Inhibition Synergizes with Gemcitabine Initially by Destabilizing the DNA Replication Apparatus
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DOI：
10.1158/0008-5472.can-14-3347
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发表时间：
2015-09-01
期刊：
影响因子：
11.2
通讯作者：
Jodrell, Duncan I.
中科院分区：
文献类型：
--
作者：
Koh, Siang-Boon;Courtin, Aurelie;Jodrell, Duncan I.
将细胞周期检查点激酶抑制剂与DNA损伤化疗剂吉西他滨联合使用提供了临床吸引力，其机制原理主要基于消除吉西他滨诱导的G（2）-M检查点激活。然而，从化疗增敏研究中得到的支持这一机制原理的证据并不一致。在这里，我们报告了一个系统的定义如何携带突变p53的胰腺癌细胞对这种联合治疗，通过结合数学模型与大规模的定量生物学分析的单细胞和细胞群体。值得注意的是，我们发现了吉西他滨和CHK 1抑制剂在不同比例下的机制效应的动态范围。值得注意的是，即使细胞表现出明显的功能性G（2）-M监视机制，也能获得有效的协同作用，如缺乏明显的过早CDK 1激活和S期有丝分裂进入。与这些发现相一致的是，在处理过的细胞中，S-G（2）持续时间延长，导致一组可定义的谱系依赖性灾难性结局。在协同药物浓度下，全局复制应激是化学增敏的一个独特指标，其分子特征是S期细胞积累高水平的超磷酸化RPA负载的单链DNA。在这些细胞的一小部分中，观察到持续的基因组损伤，包括染色体片段化和着丝粒区域的丢失，这阻止了正确的着丝粒微管附着。总之，我们的研究结果表明了药物协同作用的“临门一脚”机制，其中细胞不是通过坦率的G（2）-M期废除而被破坏，而是通过启动解除DNA合成调节的累积遗传毒性。（C）2015年AACR。
Combining cell-cycle checkpoint kinase inhibitors with the DNA-damaging chemotherapeutic agent gemcitabine offers clinical appeal, with a mechanistic rationale based chiefly on abrogation of gemcitabine-induced G(2)-M checkpoint activation. However, evidence supporting this mechanistic rationale from chemosensitization studies has not been consistent. Here we report a systematic definition of how pancreatic cancer cells harboring mutant p53 respond to this combination therapy, by combining mathematical models with large-scale quantitative biologic analyses of single cells and cell populations. Notably, we uncovered a dynamic range of mechanistic effects at different ratios of gemcitabine and CHK1 inhibitors. Remarkably, effective synergy was attained even where cells exhibited an apparently functional G(2)-M surveillance mechanism, as exemplified by a lack of both overt premature CDK1 activation and S-phase mitotic entry. Consistent with these findings, S-G(2) duration was extended in treated cells, leading to a definable set of lineage-dependent catastrophic fates. At synergistic drug concentrations, global replication stress was a distinct indicator of chemosensitization as characterized molecularly by an accumulation of S-phase cells with high levels of hyperphosphorylated RPA-loaded single-stranded DNA. In a fraction of these cells, persistent genomic damage was observed, including chromosomal fragmentation with a loss of centromeric regions that prevented proper kinetochore-microtubule attachment. Together, our results suggested a "foot-in-the-door" mechanism for drug synergy where cells were destroyed not by frank G(2)-M phase abrogation but rather by initiating a cumulative genotoxicity that deregulated DNA synthesis. (C)2015 AACR.