title: E3 ubiquitin ligase HOIP attenuates apoptotic cell death induced by cisplatin.
abstract: The genotoxin cisplatin is commonly used in chemotherapy to treat solid tumors, yet our understanding of the mechanism underlying the drug response is limited. In a focused siRNA screen, using an siRNA library targeting genes involved in ubiquitin and ubiquitin-like signaling, we identified the E3 ubiquitin ligase HOIP as a key regulator of cisplatin-induced genotoxicity. HOIP forms, with SHARPIN and HOIL-1L, the linear ubiquitin assembly complex (LUBAC). We show that cells deficient in the HOIP ligase complex exhibit hypersensitivity to cisplatin. This is due to a dramatic increase in caspase-8/caspase-3-mediated apoptosis that is strictly dependent on ATM-, but not ATR-mediated DNA damage checkpoint activation. Moreover, basal and cisplatin-induced activity of the stress response kinase JNK is enhanced in HOIP-depleted cells and, conversely, JNK inhibition can increase cellular resistance to cisplatin and reverse the apoptotic hyperactivation in HOIP-depleted cells. Furthermore, we show that HOIP depletion sensitizes cancer cells, derived from carcinomas of various origins, through an enhanced apoptotic cell death response. We also provide evidence that ovarian cancer cells classified as cisplatin-resistant can regain sensitivity following HOIP downregulation. Cumulatively, our study identifies a HOIP-regulated antiapoptotic signaling pathway, and we envisage HOIP as a potential target for the development of combinatorial chemotherapies to potentiate the efficacy of platinum-based anticancer drugs.
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Science, University of Dundee, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: MacKay
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Science, University of Dundee, UK.
authors.forename: Eilís
authors.initials: E
authors.lastname: Carroll
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Science, University of Dundee, UK.
authors.forename: Adel F M
authors.initials: AFM
authors.lastname: Ibrahim
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Science, University of Dundee, UK.
authors.forename: Amit
authors.initials: A
authors.lastname: Garg
authors.affiliation: Division of Cancer Research, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK.
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Inman
authors.affiliation: Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, UK.
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Hay
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Science, University of Dundee, UK.
authors.forename: Arno F
authors.initials: AF
authors.lastname: Alpi
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D059447:Cell Cycle Checkpoints / Q000502:physiology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002945:Cisplatin / Q000494:pharmacology*; D004249:DNA Damage; D005260:Female; D045325:HCT116 Cells; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D034741:RNA, Small Interfering; C558338:RNF31 protein, human; D044767:Ubiquitin-Protein Ligases; D048670:MAP Kinase Kinase 4; D002945:Cisplatin