Center for Tumor Biology and Immunology, Department of Gastroenterology, Endocrinology and Metabolism, University Hospital of Marburg, Philipps-University Marburg, Marburg, Germany; Department of Medicine A - Hematology, Oncology and Pneumology, University Hospital Münster, Muenster, Germany.
Center for Tumor Biology and Immunology, Department of Gastroenterology, Endocrinology and Metabolism, University Hospital of Marburg, Philipps-University Marburg, Marburg, Germany.
Neoplasia. 2024 Nov;57:101038. doi: 10.1016/j.neo.2024.101038. Epub 2024 Aug 10.
The 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.
ATR-CHK1 通路在 DNA 损伤反应中起着至关重要的作用，因此是癌症治疗的一个有吸引力的靶点。ATR 抑制剂的抗肿瘤作用至少部分是由于 ATR 与各种 DNA 修复基因之间的合成致死性。在以前的研究中，我们已经确定 B 族 DNA 聚合酶的成员是 ATR 的潜在致死性伙伴，即 POLD1 和 PRIM1。在这项研究中，我们验证并描述了 ATR 和 POLA1 之间的合成致死性。首先，我们应用 ATR 缺陷的 DLD-1 人结直肠癌细胞模型，通过化学 POLA1 抑制来证实合成致死性。通过 FACS 和 Western blot 分析细胞周期和凋亡标志物，我们能够表明凋亡和 S 期阻滞导致 ATR 缺陷型癌细胞对 POLA1 抑制剂的敏感性增加。重要的是，siRNA 介导的 POLA1 在 ATR 缺陷型细胞中的耗竭在细胞活力受损和凋亡标志物累积方面产生了类似的效果，从而排除了化学 POLA1 抑制的毒性作用。相反，我们证明了 siRNA 介导的 POLA1 耗竭使几种癌细胞系对 ATR 和其主要效应激酶 CHK1 的化学抑制更加敏感。总之，ATR/CHK1 和 POLA1 之间的合成致死性可能代表一种新的、有前途的个体化癌症治疗方法：首先，POLA1 的改变可以作为增加对 ATR 和 CHK1 抑制剂敏感性的筛选参数。其次，ATR-CHK1 通路的改变可能预示着对 POLA1 抑制剂的敏感性增加。
