BRCA2 reversion mutation-independent resistance to PARP inhibition through impaired DNA prereplication complex function

• 成果类型: Article
• 署名作者: Pappas, Kyrie; Ferrari, Matteo; Smith, Perianne; Nandakumar, Subhiksha; Khan, Zahra; Young, Serina B.; Laclair, Justin; Russo, Marco Vincenzo; Hobbs, Emmet Huang; Schultz, Nikolaus; Abida, Wassim; Karthaus, Wouter; Jasin, Maria; Sawyers, Charles L.
• 署名单位: Memorial Sloan Kettering Cancer Center; Memorial Sloan Kettering Cancer Center; University of Minnesota System; University of Minnesota Twin Cities; Memorial Sloan Kettering Cancer Center; Memorial Sloan Kettering Cancer Center; Columbia University; NewYork-Presbyterian Hospital; Albany Medical College; University of Miami; Memorial Sloan Kettering Cancer Center; Swiss Institute Experimental Cancer Research; Swiss Federal Institutes of Technology Domain; Ecole Polytechnique Federale de Lausanne; Howard Hughes Medical Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13568
• DOI: 10.1073/pnas.2426743122
• 发表日期: 2025-06-03
• 关键词: repair; roles

摘要

Recent approvals of polymeric adenosine diphosphate ribose (poly(ADP-ribose) polymerase inhibitors (PARPi) for BRCA-mutant metastatic castration resistant prostate cancer necessitate an understanding of the factors that shape sensitivity and resistance. Reversion mutations that restore homologous recombination (HR) repair are detected in similar to 50 to 80% of BRCA-mutant patients who respond but subsequently relapse, but there is currently little insight into why only similar to 50% of BRCA-mutant patients display upfront resistance. To address this question, we performed a genome-wide CRISPR screen to identify genomic determinants of PARPi resistance in murine Brca2 Delta/Delta prostate organoids genetically engineered in a manner that precludes the development of reversion mutations. Remarkably, we recovered multiple independent single guide RNAs (sgRNAs) targeting three different members (Cdt1, Cdc6, and Dbf4) of the DNA prereplication complex (pre-RC), each of which independently conferred resistance to olaparib and the next-generation PARP-1 selective inhibitorAZD5305. Moreover, sensitivity to PARP inhibition was restored in Brca2 Delta/Delta, Cdc6-depleted prostate cells by knockdown of geminin, a negative regulator of Cdt1, further implicating the critical role of a functional pre-RC complex in PARPi sensitivity. Furthermore, similar to 50% of CRPC tumors have copy number loss of pre-RC complex genes, particularly CDT1. Mechanistically, prostate cells with impaired pre-RC activity displayed rapid resolution of olaparib-induced DNA damage as well as protection from replication fork degradation caused by Brca2 loss, providing insight into how Brca2-mutant cancer cells can escape cell death from replication stress induced by PARP inhibition in the absence of HR repair. Of note, a pharmacologic inhibitor that targets the CDT1/geminin complex (AF615) restored sensitivity to AZD5305, providing a potential translational avenue to enhance sensitivity to PARP inhibition.