Title: Loss of E2F7 confers resistance to poly-ADP-ribose polymerase (PARP) inhibitors in BRCA2-deficient cells.
Authors: Clements, Kristen E; Thakar, Tanay; Nicolae, Claudia M; Liang, Xinwen; Wang, Hong-Gang; Moldovan, George-Lucian
Published In Nucleic Acids Res, (2018 09 28)
Abstract: BRCA proteins are essential for homologous recombination (HR) DNA repair, and their germline or somatic inactivation is frequently observed in human tumors. Understanding the molecular mechanisms underlying the response of BRCA-deficient tumors to chemotherapy is paramount for developing improved personalized cancer therapies. While PARP inhibitors have been recently approved for treatment of BRCA-mutant breast and ovarian cancers, not all patients respond to this therapy, and resistance to these novel drugs remains a major clinical problem. Several mechanisms of chemoresistance in BRCA2-deficient cells have been identified. Rather than restoring normal recombination, these mechanisms result in stabilization of stalled replication forks, which can be subjected to degradation in BRCA2-mutated cells. Here, we show that the transcriptional repressor E2F7 modulates the chemosensitivity of BRCA2-deficient cells. We found that BRCA2-deficient cells are less sensitive to PARP inhibitor and cisplatin treatment after E2F7 depletion. Moreover, we show that the mechanism underlying this activity involves increased expression of RAD51, a target for E2F7-mediated transcriptional repression, which enhances both HR DNA repair, and replication fork stability in BRCA2-deficient cells. Our work describes a new mechanism of therapy resistance in BRCA2-deficient cells, and identifies E2F7 as a putative biomarker for tumor response to PARP inhibitor therapy.
PubMed ID: 30032296
MeSH Terms: Antineoplastic Agents/pharmacology*; BRCA2 Protein/deficiency*; CRISPR-Cas Systems; Cell Line, Tumor; DNA Replication/drug effects; DNA Replication/physiology; DNA, Neoplasm/genetics; DNA, Neoplasm/metabolism; Drug Resistance, Neoplasm/physiology*; E2F7 Transcription Factor/deficiency; E2F7 Transcription Factor/physiology*; Enzyme Inhibitors/pharmacology*; Gene Knockout Techniques; Genes, BRCA2; Humans; Neoplasm Proteins/deficiency; Neoplasm Proteins/physiology*; Phthalazines/pharmacology; Piperazines/pharmacology; Poly(ADP-ribose) Polymerases; Rad51 Recombinase/biosynthesis; Rad51 Recombinase/genetics; Recombinational DNA Repair/drug effects; Recombinational DNA Repair/physiology