BRCA2 reversion mutation–independent resistance to PARP inhibition through impaired DNA prereplication complex function Journal Article
| Authors: | Pappas, K.; Ferrari, M.; Smith, P.; Nandakumar, S.; Khan, Z.; Young, S. B.; LaClair, J.; Russo, M. V.; Huang-Hobbs, E.; Schultz, N.; Abida, W.; Karthaus, W.; Jasin, M.; Sawyers, C. L. |
| Article Title: | BRCA2 reversion mutation–independent resistance to PARP inhibition through impaired DNA prereplication complex function |
| Abstract: | 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 ~50 to 80% of BRCA-mutant patients who respond but subsequently relapse, but there is currently little insight into why only ~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 Brca2Δ/Δ 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 inhibitor AZD5305. Moreover, sensitivity to PARP inhibition was restored in Brca2Δ/Δ, 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, ~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. Copyright © 2025 the Author(s). |
| Keywords: | immunohistochemistry; controlled study; protein expression; gene mutation; genetics; mutation; nonhuman; dna replication; sensitivity analysis; cell proliferation; cell cycle protein; animal cell; mouse; phenotype; animal; metabolism; animals; cell cycle proteins; mice; animal tissue; cell death; cell viability; homologous recombination; gene expression; animal experiment; animal model; immunofluorescence; drug effect; drug resistance; drug resistance, neoplasm; brca2 protein; prostate cancer; prostate; cell culture; immunoblotting; nicotinamide adenine dinucleotide adenosine diphosphate ribosyltransferase inhibitor; piperazines; castration; drug therapy; piperazine derivative; nicotinamide adenine dinucleotide adenosine diphosphate ribosyltransferase; histone h2ax; olaparib; castration resistant prostate cancer; genotyping; phthalazine derivative; phthalazines; cdt1; replication licensing factor cdt1; cell cycle protein 6; parp; recombination repair; humans; human; male; article; prostatic neoplasms, castration-resistant; clustered regularly interspaced short palindromic repeat; revertant; organoid; poly(adp-ribose) polymerase inhibitors; crispr-cas9 system; geminin; saruparib; brca2 protein, mouse |
| Journal Title: | Proceedings of the National Academy of Sciences of the United States of America |
| Volume: | 122 |
| Issue: | 23 |
| ISSN: | 0027-8424 |
| Publisher: | National Academy of Sciences |
| Publication status: | Published |
| Date Published: | 2025-06-01 |
| Start Page: | e2426743122 |
| Language: | English |
| DOI: | 10.1073/pnas.2426743122 |
| PUBMED: | 40460119 |
| PROVIDER: | scopus |
| PMCID: | PMC12167974 |
| DOI/URL: | |
| Notes: | The MSK Cancer Center Support Grant (P30 CA008748) is acknowledged in the PubMed record. Corresponding MSK author is Charles L. Sawyers -- Source: Scopus |
Altmetric
Citation Impact
BMJ Impact Analytics
MSK Authors
Related MSK Work