title: BRCA2 and RAD51 promote double-strand break formation and cell death in response to gemcitabine.
abstract: Replication inhibitors cause replication fork stalling and double-strand breaks (DSB) that result from processing of stalled forks. During recovery from replication blocks, the homologous recombination (HR) factor RAD51 mediates fork restart and DSB repair. HR defects therefore sensitize cells to replication inhibitors, with clear implications for cancer therapy. Gemcitabine is a potent replication inhibitor used to treat cancers with mutations in HR genes such as BRCA2. Here, we investigate why, paradoxically, mutations in HR genes protect cells from killing by gemcitabine. Using DNA replication and DNA damage assays in mammalian cells, we show that even short gemcitabine treatments cause persistent replication inhibition. BRCA2 and RAD51 are recruited to chromatin early after removal of the drug, actively inhibit replication fork progression, and promote the formation of MUS81- and XPF-dependent DSBs that remain unrepaired. Our data suggest that HR intermediates formed at gemcitabine-stalled forks are converted into DSBs and thus contribute to gemcitabine-induced cell death, which could have implications for the treatment response of HR-deficient tumors.
authors: School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors: Rebecca M
authors: RM
authors: Jones
authors: School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors: Panagiotis
authors: P
authors: Kotsantis
authors: School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors: Grant S
authors: GS
authors: Stewart
authors: Science for Life Laboratory, Karolinska Institutet Science Park, Solna, Sweden.
authors: Petra
authors: P
authors: Groth
authors: School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom. e.petermann@bham.ac.uk.
authors: Eva
authors: E
authors: Petermann
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D024682:BRCA2 Protein / Q000235:genetics* / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival; D053903:DNA Breaks, Double-Stranded; D004261:DNA Replication / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D061986:MCF-7 Cells; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D051135:Rad51 Recombinase / Q000235:genetics* / Q000378:metabolism; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D024682:BRCA2 Protein; C551750:BRCA2 protein, human; D003841:Deoxycytidine; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000093542:Gemcitabine