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Nat Commun. 2018 May 10;9(1):1849. doi: 10.1038/s41467-018-03917-2.

Genome-wide and high-density CRISPR-Cas9 screens identify point mutations in PARP1 causing PARP inhibitor resistance.

Author information

1
The CRUK Gene Function Laboratory, The Institute of Cancer Research, London, SW3 6JB, UK.
2
Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, SW3 6JB, UK.
3
Institute of Molecular Biology "Roumen Tsanev", Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria.
4
University of Washington School of Medicine, 1959 NE Pacific St, Seattle, WA, 98195, USA.
5
Divison of Structural Biology, The Institute of Cancer Research, London, SW3 6JB, UK.
6
Tumour Profiling Unit, The Institute of Cancer Research, London, SW3 6JB, UK.
7
Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA.
8
Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK.
9
UCSF Helen Diller Family Comprehensive Cancer Center, 1450 3rd St, San Francisco, CA, 94158, USA. Alan.Ashworth@ucsf.edu.
10
The CRUK Gene Function Laboratory, The Institute of Cancer Research, London, SW3 6JB, UK. Chris.Lord@icr.ac.uk.
11
Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, SW3 6JB, UK. Chris.Lord@icr.ac.uk.

Abstract

Although PARP inhibitors (PARPi) target homologous recombination defective tumours, drug resistance frequently emerges, often via poorly understood mechanisms. Here, using genome-wide and high-density CRISPR-Cas9 "tag-mutate-enrich" mutagenesis screens, we identify close to full-length mutant forms of PARP1 that cause in vitro and in vivo PARPi resistance. Mutations both within and outside of the PARP1 DNA-binding zinc-finger domains cause PARPi resistance and alter PARP1 trapping, as does a PARP1 mutation found in a clinical case of PARPi resistance. This reinforces the importance of trapped PARP1 as a cytotoxic DNA lesion and suggests that PARP1 intramolecular interactions might influence PARPi-mediated cytotoxicity. PARP1 mutations are also tolerated in cells with a pathogenic BRCA1 mutation where they result in distinct sensitivities to chemotherapeutic drugs compared to other mechanisms of PARPi resistance (BRCA1 reversion, 53BP1, REV7 (MAD2L2) mutation), suggesting that the underlying mechanism of PARPi resistance that emerges could influence the success of subsequent therapies.

PMID:
29748565
PMCID:
PMC5945626
DOI:
10.1038/s41467-018-03917-2
[Indexed for MEDLINE]
Free PMC Article

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