The CRUK Gene Function Laboratory, London, UK.
Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, UK.
Nat Cell Biol. 2022 Jan;24(1):62-73. doi: 10.1038/s41556-021-00807-6. Epub 2022 Jan 10.
Poly (ADP-ribose) polymerase (PARP) inhibitors elicit antitumour activity in homologous recombination-defective cancers by trapping PARP1 in a chromatin-bound state. How cells process trapped PARP1 remains unclear. Using wild-type and a trapping-deficient PARP1 mutant combined with rapid immunoprecipitation mass spectrometry of endogenous proteins and Apex2 proximity labelling, we delineated mass spectrometry-based interactomes of trapped and non-trapped PARP1. These analyses identified an interaction between trapped PARP1 and the ubiquitin-regulated p97 ATPase/segregase. We found that following trapping, PARP1 is SUMOylated by PIAS4 and subsequently ubiquitylated by the SUMO-targeted E3 ubiquitin ligase RNF4, events that promote recruitment of p97 and removal of trapped PARP1 from chromatin. Small-molecule p97-complex inhibitors, including a metabolite of the clinically used drug disulfiram (CuET), prolonged PARP1 trapping and enhanced PARP inhibitor-induced cytotoxicity in homologous recombination-defective tumour cells and patient-derived tumour organoids. Together, these results suggest that p97 ATPase plays a key role in the processing of trapped PARP1 and the response of tumour cells to PARP inhibitors.
聚（ADP-核糖）聚合酶（PARP）抑制剂通过将 PARP1 捕获在染色质结合状态下，在同源重组缺陷型癌症中发挥抗肿瘤活性。细胞如何处理捕获的 PARP1 尚不清楚。本研究使用野生型和捕获缺陷型 PARP1 突变体，结合内源性蛋白质的快速免疫沉淀质谱分析和 Apex2 邻近标记，描绘了捕获和未捕获 PARP1 的基于质谱的相互作用组。这些分析确定了捕获的 PARP1 与泛素调节的 p97 ATPase/segregase 之间的相互作用。研究发现，在捕获后，PARP1 被 PIAS4 进行 SUMO 化，随后被 SUMO 靶向 E3 泛素连接酶 RNF4 进行泛素化，这些事件促进了 p97 的招募和从染色质上除去捕获的 PARP1。小分子 p97 复合物抑制剂，包括临床使用药物双硫仑（disulfiram）的代谢产物（CuET），延长了 PARP1 的捕获，并增强了同源重组缺陷型肿瘤细胞和患者来源的肿瘤类器官对 PARP 抑制剂的细胞毒性。这些结果表明，p97 ATPase 在捕获的 PARP1 的处理和肿瘤细胞对 PARP 抑制剂的反应中发挥关键作用。
