Gemcitabine sensitization by checkpoint kinase 1 inhibition correlates with inhibition of a Rad51 DNA damage response in pancreatic cancer cells.
Gemcitabine sensitization by checkpoint kinase 1 inhibition correlates with inhibition of a Rad51 DNA damage response in pancreatic cancer cells.
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DOI：
10.1158/1535-7163.mct-08-0662
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发表时间：
2009-01
影响因子：
5.7
通讯作者：
Maybaum J
中科院分区：
文献类型：
--
作者：
Parsels LA;Morgan MA;Tanska DM;Parsels JD;Palmer BD;Booth RJ;Denny WA;Canman CE;Kraker AJ;Lawrence TS;Maybaum J
蛋白激酶Chk 1被认为是细胞周期进程和DNA修复的关键调节剂，以及Chk 1的抑制剂（例如，UCN-01、EXEL-9844）增强化疗药物在肿瘤细胞中的细胞毒性作用。我们检查了PD-321852（一种小分子Chk 1抑制剂）在一组胰腺癌细胞系中增强吉西他滨（Gem）诱导的克隆性死亡的能力，并评估了与Chk 1抑制和化疗增敏相关的终点之间的关系。最低毒性浓度的PD-321852的Gem化学增敏范围从Panc 1细胞中的最小值（存活率变化< 3倍）到MiaPaCa 2细胞中的30倍以上。PD-321852抑制所有细胞系中的Chk 1，如Cdc 25 A的稳定所证明，并且与Gem联合使用时，在致敏性更高的细胞系中观察到Chk 1蛋白的协同损失。然而，Gem化疗增敏与S/M或G2/M检查点的消除无关; PD-321852未诱导Gem处理的BxPC 3或M-Panc 96细胞中的过早有丝分裂进入，这两种细胞分别对Gem致敏6.2倍和4.6倍。在更敏感的细胞系中，PD-321852不仅抑制GEM诱导的Rad 51病灶形成和从GEM诱导的复制应激中恢复，如γ-H2 AX的持续性所证明的，而且还耗尽这些细胞的Rad 51蛋白。我们的数据表明，这种Chk 1介导的Rad 51对GEM诱导的复制应激的反应的抑制是通过Chk 1抑制胰腺癌细胞来确定GEM化疗增敏的重要因素。
The protein kinase Chk1 has been implicated as a key regulator of cell cycle progression and DNA repair and inhibitors of Chk1 (e.g., UCN-01, EXEL-9844) potentiate the cytotoxic actions of chemotherapeutic drugs in tumor cells. We have examined the ability of PD-321852, a small-molecule Chk1 inhibitor, to potentiate gemcitabine (Gem)-induced clonogenic death in a panel of pancreatic cancer cell lines, and evaluated the relationship between endpoints associated with Chk1 inhibition and chemosensitization. Gem chemosensitization by minimally-toxic concentrations of PD-321852 ranged from minimal (< 3 fold change in survival) in Panc1 cells, to over 30-fold in MiaPaCa2 cells. PD-321852 inhibited Chk1 in all cell lines, as evidenced by stabilization of Cdc25A, and, in combination with Gem, a synergistic loss of Chk1 protein was observed in the more sensitized cell lines. Gem chemosensitization, however, did not correlate with abrogation of the S/M or G2/M checkpoint; PD-321852 did not induce premature mitotic entry in Gem-treated BxPC3 or M-Panc96 cells, which were sensitized to Gem 6.2- and 4.6-fold, respectively. In the more sensitized cells lines, PD-321852 not only inhibited Gem-induced Rad51 focus formation and the recovery from Gem-induced replication stress, as evidenced by persistence of γ-H2AX, but also depleted these cells of Rad51 protein. Our data suggest the inhibition of this Chk1-mediated Rad51 response to Gem-induced replication stress is an important factor in determining Gem chemosensitization by Chk1 inhibition in pancreatic cancer cells.