title: Nitric oxide-dependent pro-oxidant and pro-apoptotic effect of metallothioneins in HL-60 cells challenged with cupric nitrilotriacetate.
abstract: Intracellular safeguarding functions of metallothioneins (MTs) include sequestering transition and heavy metals, scavenging free radicals and protecting against electrophiles. We report that MT protection against Cu-induced cytotoxicity can be reversed and pro-oxidant and pro-apoptotic effects can be induced in HL-60 cells exposed to NO. We demonstrate that in ZnCl(2)-pretreated HL-60 cells loaded with copper nitrilotriacetate (Cu-NTA), exposure to an NO donor, S-nitroso-N-acetyl penicillamine, resulted in S-nitrosylation and oxidation of MT cysteines. This disruption of MT Cu-binding thiolate clusters caused loosening and release of redox-active Cu, enhanced redox-cycling activity of Cu and increased peroxidation of major classes of membrane phospholipids. We also found that Cu-induced oxidative stress in ZnCl(2)-pretreated/Cu-NTA-loaded HL-60 cells was accompanied by apoptosis documented by characteristic changes of nuclear morphology, internucleosomal DNA cleavage, externalization of phosphatidylserine, release of cytochrome c from mitochondria into cytosol and activation of caspase-3. We conclude that in Cu-challenged cells, NO can reverse the protective role of MTs and convert them into pro-oxidant, pro-apoptotic implements.
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, 260 Kappa Drive, Pittsburgh, PA 15238, U.S.A.
authors.forename: S
authors.initials: S
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Kawai
authors.forename: V A
authors.initials: VA
authors.lastname: Tyurin
authors.forename: Y Y
authors.initials: YY
authors.lastname: Tyurina
authors.forename: G G
authors.initials: GG
authors.lastname: Borisenko
authors.forename: J P
authors.initials: JP
authors.lastname: Fabisiak
authors.forename: P J
authors.initials: PJ
authors.lastname: Quinn
authors.forename: B R
authors.initials: BR
authors.lastname: Pitt
authors.forename: V E
authors.initials: VE
authors.lastname: Kagan
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002273:Carcinogens / Q000494:pharmacology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation; D018922:HL-60 Cells; D006801:Humans; D015227:Lipid Peroxidation; D008668:Metallothionein / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000378:metabolism; D009571:Nitrilotriacetic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*; D009942:Organometallic Compounds / Q000494:pharmacology*; D016877:Oxidants / Q000378:metabolism*; D010084:Oxidation-Reduction; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D017304:Annexin A5; D002273:Carcinogens; D002712:Chlorides; D003574:Cytochrome c Group; D020030:Nitric Oxide Donors; D009942:Organometallic Compounds; D016877:Oxidants; D010743:Phospholipids; C110881:S-nitro-N-acetylpenicillamine; D017967:Zinc Compounds; D009569:Nitric Oxide; C016837:zinc chloride; D008668:Metallothionein; C060581:cupric nitrilotriacetate; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D010396:Penicillamine; D009571:Nitrilotriacetic Acid