ATR-CHK1途径在DNA损伤反应中起着重要作用,因此是癌症治疗中一个有吸引力的靶标。ATR抑制剂的抗肿瘤作用至少部分由ATR和各种DNA修复基因之间的合成致死性引起。在以往的研究中,我们已经确定B家族DNA聚合酶的成员是ATR的潜在致死伴侣,即POLD1和PRIM1。在这项研究中,我们验证并表征了ATR和POLA1之间的合成致死性。首先,我们应用ATR缺陷型DLD-1人结直肠癌细胞模型,通过化学抑制POLA1来确认合成致死性.通过FACS和Western印迹分析细胞周期和凋亡标志物,我们能够证明细胞凋亡和S期阻滞有助于ATR缺陷型癌细胞对POLA1抑制剂的敏感性增加.重要的是,在ATR缺陷型细胞中siRNA介导的POLA1耗竭在受损的细胞活力和凋亡标志物的累积方面引起了类似的作用,从而排除了化学POLA1抑制作用的毒性作用。相反,我们证明了siRNA介导的POLA1耗竭使几种癌细胞对ATR及其主要效应激酶CHK1的化学抑制敏感。总之,ATR/CHK1和POLA1之间的合成致死性可能代表了一种新颖且有希望的个体化癌症治疗方法:POLA1的改变可以作为对ATR和CHK1抑制剂敏感性增加的筛选参数.第二,ATR-CHK1通路的改变可能预示着对POLA1抑制剂的敏感性增加.
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ATR-CHK1 pathway plays a fundamental role in the DNA damage response and is therefore an attractive target in cancer therapy. The antitumorous effect of
ATR inhibitors is at least partly caused by synthetic lethality between
ATR and various DNA repair genes. In previous studies, we have identified members of the B-family DNA polymerases as potential lethal partner for
ATR, i.e. POLD1 and PRIM1. In this study, we validated and characterized the synthetic lethality between
ATR and POLA1. First, we applied a model of ATR-deficient DLD-1 human colorectal cancer cells to confirm synthetic lethality by using chemical POLA1 inhibition. Analyzing cell cycle and apoptotic markers via FACS and Western blotting, we were able to show that apoptosis and S phase arrest contributed to the increased sensitivity of ATR-deficient cancer cells towards POLA1 inhibitors. Importantly, siRNA-mediated POLA1 depletion in
ATR-deficient cells caused similar effects in regard to impaired cell viability and cumulation of apoptotic markers, thus excluding toxic effects of chemical POLA1 inhibition. Conversely, we demonstrated that siRNA-mediated POLA1 depletion sensitized several cancer cell lines towards chemical inhibition of ATR and its main effector kinase CHK1. In conclusion, the synthetic lethality between ATR/CHK1 and POLA1 might represent a novel and promising approach for individualized cancer therapy: First, alterations of POLA1 could serve as a screening parameter for increased sensitivity towards ATR and CHK1 inhibitors. Second, alterations in the ATR-CHK1 pathway might predict in increased sensitivity towards POLA1 inhibitors.