title: Werner syndrome helicase has a critical role in DNA damage responses in the absence of a functional fanconi anemia pathway.
abstract: Werner syndrome is genetically linked to mutations in WRN that encodes a DNA helicase-nuclease believed to operate at stalled replication forks. Using a newly identified small-molecule inhibitor of WRN helicase (NSC 617145), we investigated the role of WRN in the interstrand cross-link (ICL) response in cells derived from patients with Fanconi anemia, a hereditary disorder characterized by bone marrow failure and cancer. In FA-D2(-/-) cells, NSC 617145 acted synergistically with very low concentrations of mitomycin C to inhibit proliferation in a WRN-dependent manner and induce double-strand breaks (DSB) and chromosomal abnormalities. Under these conditions, ataxia-telangiectasia mutated activation and accumulation of DNA-dependent protein kinase, catalytic subunit pS2056 foci suggested an increased number of DSBs processed by nonhomologous end-joining (NHEJ). Rad51 foci were also elevated in FA-D2(-/-) cells exposed to NSC 617145 and mitomycin C, suggesting that WRN helicase inhibition interferes with later steps of homologous recombination at ICL-induced DSBs. Thus, when the Fanconi anemia pathway is defective, WRN helicase inhibition perturbs the normal ICL response, leading to NHEJ activation. Potential implication for treatment of Fanconi anemia-deficient tumors by their sensitization to DNA cross-linking agents is discussed.
authors.affiliation: Laboratory of Molecular Gerontology, National Institute on Aging, NIH Biomedical Research Center, NIH, Baltimore, MD 21224, USA.
authors.forename: Monika
authors.initials: M
authors.lastname: Aggarwal
authors.forename: Taraswi
authors.initials: T
authors.lastname: Banerjee
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Sommers
authors.forename: Chiara
authors.initials: C
authors.lastname: Iannascoli
authors.forename: Pietro
authors.initials: P
authors.lastname: Pichierri
authors.forename: Robert H
authors.initials: RH
authors.lastname: Shoemaker
authors.forename: Robert M
authors.initials: RM
authors.lastname: Brosh
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002843:Chromatin / Q000235:genetics; D043171:Chromosomal Instability; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D004261:DNA Replication / Q000187:drug effects; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005090:Exodeoxyribonucleases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D005199:Fanconi Anemia / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045325:HCT116 Cells; D006367:HeLa Cells; D006801:Humans; D008301:Maleimides / Q000494:pharmacology*; D016685:Mitomycin / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051135:Rad51 Recombinase / Q000378:metabolism; D053484:RecQ Helicases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000071657:Werner Syndrome Helicase
chemical_list: D000477:Alkylating Agents; D002843:Chromatin; D004791:Enzyme Inhibitors; D008301:Maleimides; C584579:NSC 617145; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D016685:Mitomycin; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D051135:Rad51 Recombinase; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase