Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic.
Nat Commun. 2024 Aug 27;15(1):7375. doi: 10.1038/s41467-024-51667-1.
PARP inhibitors (PARPi), known for their ability to induce replication gaps and accelerate replication forks, have become potent agents in anticancer therapy. However, the molecular mechanism underlying PARPi-induced fork acceleration has remained elusive. Here, we show that the first PARPi-induced effect on DNA replication is an increased replication fork rate, followed by a secondary reduction in origin activity. Through the systematic knockdown of human DNA polymerases, we identify POLA1 as mediator of PARPi-induced fork acceleration. This acceleration depends on both DNA polymerase α and primase activities. Additionally, the depletion of POLA1 increases the accumulation of replication gaps induced by PARP inhibition, sensitizing cells to PARPi. BRCA1-depleted cells are especially susceptible to the formation of replication gaps under POLA1 inhibition. Accordingly, BRCA1 deficiency sensitizes cells to POLA1 inhibition. Thus, our findings establish the POLA complex as important player in PARPi-induced fork acceleration and provide evidence that lagging strand synthesis represents a targetable vulnerability in BRCA1-deficient cells.
聚腺苷二磷酸核糖聚合酶（PARP）抑制剂以诱导复制间隙和加速复制叉而闻名，已成为癌症治疗中的有效药物。然而，PARPi 诱导的叉加速的分子机制仍难以捉摸。在这里，我们表明 PARPi 对 DNA 复制的第一个影响是复制叉速率的增加，随后是原点活性的二次降低。通过对人 DNA 聚合酶的系统敲低，我们鉴定出 POLA1 是 PARPi 诱导的叉加速的介质。这种加速依赖于 DNA 聚合酶α和引物酶的活性。此外，POLA1 的耗竭会增加 PARP 抑制诱导的复制间隙的积累，使细胞对 PARPi 敏感。BRCA1 缺失细胞在 POLA1 抑制下特别容易形成复制间隙。因此，BRCA1 缺陷使细胞对 POLA1 抑制敏感。因此，我们的研究结果确立了 POLA 复合物是 PARPi 诱导的叉加速的重要参与者，并提供了证据表明滞后链合成是 BRCA1 缺陷细胞中可靶向的脆弱性。
