title: Triggering autophagic cell death with a di-manganese(II) developmental therapeutic.
abstract: There is an unmet need for novel metal-based chemotherapeutics with alternative modes of action compared to clinical agents such as cisplatin and metallo-bleomycin. Recent attention in this field has focused on designing intracellular ROS-mediators as powerful cytotoxins of human cancers and identifying potentially unique toxic mechanisms underpinning their utility. Herein, we report the developmental di-manganese(II) therapeutic [Mn2(μ-oda)(phen)4(H2O)2][Mn2(μ-oda)(phen)4(oda)2]·4H2O (Mn-Oda) induces autophagy-promoted apoptosis in human ovarian cancer cells (SKOV3). The complex was initially identified to intercalate DNA by topoisomerase I unwinding and circular dichroism spectroscopy. Intracellular DNA damage, detected by γH2AX and the COMET assay, however, is not linked to direct Mn-Oda free radical generation, but is instead mediated through the promotion of intracellular reactive oxygen species (ROS) leading to autophagic vacuole formation and downstream nuclear degradation. To elucidate the cytotoxic profile of Mn-Oda, a wide range of biomarkers specific to apoptosis and autophagy including caspase release, mitochondrial membrane integrity, fluorogenic probe localisation, and cell cycle analysis were employed. Through these techniques, the activity of Mn-Oda was compared directly to i.) the pro-apoptotic clinical anticancer drug doxorubicin, ii.) the multimodal histone deacetylase inhibitor suberoyanilide hydroxamic acid, and iii.) the autophagy inducer rapamycin. In conjunction with ROS-specific trapping agents and established inhibitors of autophagy, we have identified autophagy-induction linked to mitochondrial superoxide production, with confocal image analysis of SKOV3 cells further supporting autophagosome formation.
authors.affiliation: School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Creina
authors.initials: C
authors.lastname: Slator
authors.affiliation: School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Zara
authors.initials: Z
authors.lastname: Molphy
authors.affiliation: School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Vickie
authors.initials: V
authors.lastname: McKee
authors.affiliation: School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland. Electronic address: andrew.kellett@dcu.ie.
authors.forename: Andrew
authors.initials: A
authors.lastname: Kellett
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D000071182:Autophagosomes / Q000378:metabolism*; D001343:Autophagy; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002942:Circular Dichroism; D004317:Doxorubicin / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008345:Manganese / Q000737:chemistry / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism; D015394:Molecular Structure; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077337:Vorinostat
chemical_list: C000626586:(Mn2(mu-oda)(phen)4(H2O)2)(Mn2(mu-oda)(phen)4(oda)2) 4H2O; D000970:Antineoplastic Agents; D006877:Hydroxamic Acids; D009942:Organometallic Compounds; D017382:Reactive Oxygen Species; D008345:Manganese; D000077337:Vorinostat; D004317:Doxorubicin
keywords: Apoptosis; Autophagy; Cancer; Manganese; Superoxide