Clinical and Experimental Pharmacology Group, Paterson Institute for Cancer Research, University of Manchester, Manchester, UK.
Br J Pharmacol. 2010 Mar;159(6):1326-38. doi: 10.1111/j.1476-5381.2009.00607.x. Epub 2010 Jan 28.
Checkpoint kinase 2 (CHK2) is activated by DNA damage and can contribute to p53 stabilization, modulating growth arrest and/or apoptosis. We investigated the contribution of CHK2 to oxaliplatin-mediated toxicity in a colorectal cancer model.
We evaluated the ability of CHK2 small molecule inhibitors to potentiate oxaliplatin-induced toxicity. The role of CHK2 in oxaliplatin-induced apoptosis was investigated in HCT116 cells that were wild-type (WT) or KO for CHK2. Small molecule inhibitors of CHK2 were used in combination studies with oxaliplatin in this cell model.
In oxaliplatin-treated CHK2 KO cells, accelerated apoptosis was accompanied by attenuated p53 stabilization and p21(WAF-1) up-regulation correlating with increased Bax expression, cytochrome c release and elevated caspase activity. The higher levels of apoptosis in CHK2 KO cells were restored to control (WT) levels when CHK2 was re-introduced. This 'uncoupling' of p53 stabilization and Bax up-regulation in CHK2 KO cells suggested oxaliplatin-induced apoptosis was due to a p53-independent response. Combination studies revealed that CHK2 inhibitor II or debromohymenialdisine antagonized the responses to oxaliplatin. This inhibitory effect correlated with decreases in apoptosis, p53 stabilization and DNA inter-strand cross-link formation, and was dependent on the presence (but not activity) of CHK2.
Combinations of CHK2 inhibitors with oxaliplatin should further sensitize cells to oxaliplatin treatment. However, these inhibitors produced an antagonistic effect on the response to oxaliplatin, which was reversed on the re-introduction of CHK2. These observations may have implications for the use of oxaliplatin in colorectal cancer therapy in combination with therapies targeting CHK2.
DNA 损伤可激活细胞检验点激酶 2（CHK2），从而稳定 p53，调节细胞生长停滞和/或细胞凋亡。我们在结直肠癌细胞模型中研究了 CHK2 对奥沙利铂介导的细胞毒性的作用。
我们评估了 CHK2 小分子抑制剂增强奥沙利铂诱导毒性的能力。在野生型（WT）或 CHK2 敲除（KO）的 HCT116 细胞中，研究了 CHK2 在奥沙利铂诱导的细胞凋亡中的作用。在该细胞模型中，将 CHK2 小分子抑制剂与奥沙利铂联合使用进行组合研究。
在奥沙利铂处理的 CHK2 KO 细胞中，加速的细胞凋亡伴随着 p53 稳定的减弱和 p21（WAF-1）的上调，这与 Bax 表达的增加、细胞色素 c 的释放和 caspase 活性的升高相关。当 CHK2 被重新引入时，CHK2 KO 细胞中的细胞凋亡水平恢复到对照（WT）水平。在 CHK2 KO 细胞中，p53 稳定和 Bax 上调的“解偶联”表明奥沙利铂诱导的细胞凋亡是由于 p53 非依赖性反应。组合研究表明，CHK2 抑制剂 II 或 debromohymenialdisine 拮抗了奥沙利铂的反应。这种抑制作用与细胞凋亡、p53 稳定和 DNA 链间交联形成的减少相关，并且依赖于 CHK2 的存在（而非活性）。
CHK2 抑制剂与奥沙利铂的组合应进一步增强细胞对奥沙利铂治疗的敏感性。然而，这些抑制剂对奥沙利铂反应产生拮抗作用，在重新引入 CHK2 时逆转。这些观察结果可能对结直肠癌治疗中奥沙利铂与靶向 CHK2 的治疗联合使用具有重要意义。
