Department of Medical Biophysics, Faculty of Biology and Environmental Protection, Institute of Biophysics, University of Lodz, 90-236 Lodz, Poland.
Department of Genetics, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland.
Int J Mol Sci. 2020 Dec 19;21(24):9715. doi: 10.3390/ijms21249715.
Poly (ADP-ribose) polymerase inhibitor (PARPi, olaparib) impairs the repair of DNA single-strand breaks (SSBs), resulting in double-strand breaks (DSBs) that cannot be repaired efficiently in homologous recombination repair (HRR)-deficient cancers such as BRCA1/2-mutant cancers, leading to synthetic lethality. Despite the efficacy of olaparib in the treatment of BRCA1/2 deficient tumors, PARPi resistance is common. We hypothesized that the combination of olaparib with anticancer agents that disrupt HRR by targeting ataxia telangiectasia and Rad3-related protein (ATR) or checkpoint kinase 1 (CHK1) may be an effective strategy to reverse ovarian cancer resistance to olaparib. Here, we evaluated the effect of olaparib, the ATR inhibitor AZD6738, and the CHK1 inhibitor MK8776 alone and in combination on cell survival, colony formation, replication stress response (RSR) protein expression, DNA damage, and apoptotic changes in BRCA2 mutated (PEO-1) and HRR-proficient BRCA wild-type (SKOV-3 and OV-90) cells. Combined treatment caused the accumulation of DNA DSBs. PARP expression was associated with sensitivity to olaparib or inhibitors of RSR. Synergistic effects were weaker when olaparib was combined with CHK1i and occurred regardless of the BRCA2 status of tumor cells. Because PARPi increases the reliance on ATR/CHK1 for genome stability, the combination of PARPi with ATR inhibition suppressed ovarian cancer cell growth independently of the efficacy of HRR. The present results were obtained at sub-lethal doses, suggesting the potential of these inhibitors as monotherapy as well as in combination with olaparib.
聚（ADP-核糖）聚合酶抑制剂（PARPi，奥拉帕利）可损害 DNA 单链断裂（SSB）的修复，导致同源重组修复（HRR）缺陷的癌症（如 BRCA1/2 突变癌症）中无法有效修复的双链断裂（DSB），导致合成致死。尽管奥拉帕利在治疗 BRCA1/2 缺陷肿瘤方面有效，但 PARPi 耐药很常见。我们假设奥拉帕利与通过靶向共济失调毛细血管扩张症和 Rad3 相关蛋白（ATR）或检查点激酶 1（CHK1）破坏 HRR 的抗癌药物联合使用可能是逆转卵巢癌对奥拉帕利耐药的有效策略。在这里，我们评估了奥拉帕利、ATR 抑制剂 AZD6738 和 CHK1 抑制剂 MK8776 单独和联合使用对 BRCA2 突变（PEO-1）和 HRR 功能正常的 BRCA 野生型（SKOV-3 和 OV-90）细胞的细胞存活、集落形成、复制应激反应（RSR）蛋白表达、DNA 损伤和凋亡变化的影响。联合治疗导致 DNA DSB 的积累。PARP 表达与对奥拉帕利或 RSR 抑制剂的敏感性相关。当奥拉帕利与 CHK1i 联合使用时，协同作用较弱，并且与肿瘤细胞的 BRCA2 状态无关。由于 PARPi 增加了对 ATR/CHK1 的基因组稳定性的依赖，PARPi 与 ATR 抑制的联合抑制卵巢癌细胞生长独立于 HRR 的功效。这些结果是在亚致死剂量下获得的，表明这些抑制剂作为单药治疗以及与奥拉帕利联合使用具有潜在用途。
