title: Nitric oxide donors or nitrite counteract copper-[dithiocarbamate](2)-mediated tumor cell death and inducible nitric oxide synthase down-regulation: possible role of a nitrosyl-copper [dithiocarbamate](2) complex.
abstract: In contrast to other metal-dithiocarbamate [DEDTC] complexes, the copper-DEDTC complex is highly cytotoxic, inducing oxidative stress, preferentially in tumor cells. Because nitric oxide (NO) forms adducts with Cu[DEDTC](2), we investigated whether NO donors like S-nitroso-N-acetyl penicillamine (SNAP) or sodium nitroprusside (SNP), and nitrite, a NO decomposition product, modulate Cu[DEDTC](2) cytotoxicity against human tumor cells. We show that apoptosis-associated PARP cleavage and inducible nitric oxide synthase (iNOS) down-regulation induced by nanomolar Cu[DEDTC](2), are counteracted by 50 muM SNAP, SNP, or CoCl(2), an inducer of hypoxia and NO signaling. Nitrite was stochiometrically effective in antagonizing Cu[DEDTC](2) cytotoxicity and inducing shifts in the absorption spectrum of the binary complex in the 280 and 450 nm regions. Subtoxic concentrations of Cu[DEDTC](2) became lethal when tumor cells were pretreated with c-PTIO, a membrane-impermeable scavenger for extracellular NO. Our results suggest that: (a) reactive oxygen species induced by Cu[DEDTC](2) are scavenged by nitrite released from NO, (b) the extent of lethality of Cu[DEDTC](2) is dependent on the reciprocal formation of an inactive ternary Cu[DEDTC](2)NO copper-nitrosyl complex.
authors.affiliation: Instituto Venezolano de Investigaciones Cientificas (IVIC), Centre for Microbiology & Cell Biology, Tumor Cell Biology Laboratory, Apartado 20632, Caracas 1020-A, Venezuela.
authors.forename: Maricela Viola
authors.initials: MV
authors.lastname: Rhenals
authors.forename: Mary
authors.initials: M
authors.lastname: Strasberg-Rieber
authors.forename: Manuel
authors.initials: M
authors.lastname: Rieber
mesh_terms: D016923:Cell Death; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003035:Cobalt / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D015536:Down-Regulation; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008545:Melanoma; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis*; D009573:Nitrites / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D009603:Nitroso Compounds / Q000494:pharmacology; D009942:Organometallic Compounds / Q000378:metabolism* / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D012977:Sodium Nitrite / Q000494:pharmacology
chemical_list: D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D007093:Imidazoles; D020030:Nitric Oxide Donors; D009573:Nitrites; D009603:Nitroso Compounds; D009942:Organometallic Compounds; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D009599:Nitroprusside; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D009569:Nitric Oxide; D003035:Cobalt; D026423:S-Nitroso-N-Acetylpenicillamine; D052247:Nitric Oxide Synthase Type II; D011065:Poly(ADP-ribose) Polymerases; C018021:cobaltous chloride; D012977:Sodium Nitrite