title: Germline missense pathogenic variants in the BRCA1 BRCT domain, p.Gly1706Glu and p.Ala1708Glu, increase cellular sensitivity to PARP inhibitor olaparib by a dominant negative effect.
abstract: BRCA1-deficient cells show defects in DNA repair and rely on other members of the DNA repair machinery, which makes them sensitive to PARP inhibitors (PARPi). Although carrying a germline pathogenic variant in BRCA1/2 is the best determinant of response to PARPi, a significant percentage of the patients do not show sensitivity and/or display increased toxicity to the agent. Considering previously suggested mutation-specific BRCA1 haploinsufficiency, we aimed to investigate whether there are any differences in cellular response to PARPi olaparib depending on the BRCA1 mutation type. Lymphoblastoid cell lines derived from carriers of missense pathogenic variants in the BRCA1 BRCT domain (c.5117G > A, p.Gly1706Glu and c.5123C > A, p.Ala1708Glu) showed higher sensitivity to olaparib than cells with truncating variants or wild types (WT). Response to olaparib depended on a basal PARP enzymatic activity, but did not correlate with PARP1 expression. Interestingly, cellular sensitivity to the agent was associated with the level of BRCA1 recruitment into γH2AX foci, being the lowest in cells with missense variants. Since these variants lead to partially stable protein mutants, we propose a model in which the mutant protein acts in a dominant negative manner on the WT BRCA1, impairing the recruitment of BRCA1 into DNA damage sites and, consequently, increasing cellular sensitivity to PARPi. Taken together, our results indicate that carriers of different BRCA1 mutations could benefit from olaparib in a distinct way and show different toxicities to the agent, which could be especially relevant for a potential future use of PARPi as prophylactic agents in BRCA1 mutation carriers.
authors.affiliation: Human Genetics Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: Tereza
authors.initials: T
authors.lastname: Vaclová
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, Molecular and Biochemical Etiology Program, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Nicholas T
authors.initials: NT
authors.lastname: Woods
authors.affiliation: Confocal Microscopy Core Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Megías
authors.affiliation: Human Genetics Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Gomez-Lopez
authors.affiliation: Cancer Epigenetics Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Biomedical Research Institute (IDIBELL), Barcelona, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Setién
authors.affiliation: Medical Oncology Section, Complejo Hospitalario Universitario de Albacete, Albacete, Spain.
authors.forename: José María
authors.initials: JM
authors.lastname: García Bueno
authors.affiliation: Hereditary Cancer Unit, Medical Oncology Service, Hospital Morales Meseguer, Murcia, Spain.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Macías
authors.affiliation: Human Genetics Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Barroso
authors.affiliation: Familial Cancer Unit, Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Urioste
authors.affiliation: Cancer Epigenetics Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Biomedical Research Institute (IDIBELL), Barcelona, Spain.|Department of Physiological Sciences II, School of Medicine, University of Barcelona, Barcelona, Spain.|Institucio Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
authors.forename: Manel
authors.initials: M
authors.lastname: Esteller
authors.affiliation: Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, Florida, FL, USA.
authors.forename: Alvaro N A
authors.initials: ANA
authors.lastname: Monteiro
authors.affiliation: Human Genetics Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.|Spanish Network on Rare Diseases (CIBERER), Madrid, Spain.|Genotyping Unit (CEGEN), Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Benítez
authors.affiliation: Human Genetics Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.|Spanish Network on Rare Diseases (CIBERER), Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Osorio
mesh_terms: D019313:BRCA1 Protein / Q000235:genetics*; D045744:Cell Line, Tumor; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D018095:Germ-Line Mutation / Q000235:genetics; D006801:Humans; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D010793:Phthalazines / Q000008:administration & dosage*; D010879:Piperazines / Q000008:administration & dosage*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors / Q000008:administration & dosage; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics*
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D010793:Phthalazines; D010879:Piperazines; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases; C531550:olaparib