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: Monika Aggarwal, Taraswi Banerjee, Joshua A Sommers, Chiara Iannascoli, Pietro Pichierri, Robert H Shoemaker, Robert M Brosh Jr
• Journal: Cancer research (Cancer Res) Vol. 73 Issue 17 Pg. 5497-507 (Sep 01 2013) ISSN: 1538-7445 [Electronic] United States
• PMID: 23867477 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)
• Copyright: ©2013 AACR.

Chemical References

• Alkylating Agents
• Chromatin
• Enzyme Inhibitors
• Maleimides
• NSC 617145
• Nuclear Proteins
• RNA, Small Interfering
• Mitomycin
• ATM protein, human
• Ataxia Telangiectasia Mutated Proteins
• DNA-Activated Protein Kinase
• PRKDC protein, human
• Rad51 Recombinase
• Exodeoxyribonucleases
• RecQ Helicases
• WRN protein, human
• Werner Syndrome Helicase

Topics

• Alkylating Agents (pharmacology)
• Apoptosis (drug effects)
• Ataxia Telangiectasia Mutated Proteins (metabolism)
• Blotting, Western
• Cell Proliferation (drug effects)
• Chromatin (genetics)
• Chromosomal Instability
• DNA Breaks, Double-Stranded (drug effects)
• DNA Repair (drug effects)
• DNA Replication (drug effects)
• DNA-Activated Protein Kinase (metabolism)
• Drug Synergism
• Drug Therapy, Combination
• Enzyme Inhibitors (pharmacology)
• Exodeoxyribonucleases (antagonists & inhibitors, genetics, metabolism)
• Fanconi Anemia (drug therapy, genetics, pathology)
• HCT116 Cells
• HeLa Cells
• Humans
• Maleimides (pharmacology)
• Mitomycin (pharmacology)
• Nuclear Proteins (metabolism)
• RNA, Small Interfering (genetics)
• Rad51 Recombinase (metabolism)
• RecQ Helicases (antagonists & inhibitors, genetics, metabolism)
• Werner Syndrome Helicase