title: The liver-selective nitric oxide donor O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO) protects HepG2 cells against cytochrome P450 2E1-dependent toxicity.
abstract: HepG2 cells expressing CYP2E1 (E47 cells) are more susceptible to toxicity by arachidonic acid (AA) or after glutathione depletion with an inhibitor of glutamate-cysteine ligase, l-buthionine-(S,R)-sulfoximine (BSO), compared with control HepG2 cells (C34 cells). The ability of nitric oxide (NO) to protect against CYP2E1-dependent toxicity has not been evaluated. We therefore studied the ability of O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO), a liver-selective NO donor, to protect against CYP2E1-dependent toxicity and compared this with protection by chemical NO donors. E47 cells incubated with V-PYRRO/NO produced NO, whereas C34 cells did not. Incubation of E47 cells with 50 microM AA or 100 microM BSO for 2 days resulted in a 50% loss of cell viability. VPYRRO/NO (1 mM) blocked this toxicity of AA and BSO by a mechanism involving NO release via CYP2E1 metabolism of VPYRRO/NO. NO scavengers hemoglobin and 2-(4-carboxophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide blocked the protective effects of V-PYRRO/NO. V-PYRRO/NO inhibited CYP2E1 activity and production of reactive oxygen species, whereas hemoglobin prevented these events. AA and BSO induced lipid peroxidation and decreased mitochondrial membrane potential; both of these effects were blocked by V-PYRRO/NO. Unlike V-PYRRO/NO, the chemical donors spermine/NO and (S)-nitroso-N-acetylpenicillamine release NO directly when added to the medium; however, they could partially protect against the CYP2E1-dependent toxicity. These results suggest that VPYRRO/NO protects HepG2 cells against CYP2E1-dependent toxicity through inhibition of CYP2E1-derived reactive oxygen species production and lipid peroxidation by the generated NO and that this compound may be valuable in protecting against CYP2E1-dependent toxicity via liver P450-specific generation of NO.
authors.affiliation: Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, NY 10029.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Gong
authors.forename: Arthur I
authors.initials: AI
authors.lastname: Cederbaum
authors.forename: Natalia
authors.initials: N
authors.lastname: Nieto
mesh_terms: D016718:Arachidonic Acid / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019328:Buthionine Sulfoximine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism*; D004347:Drug Interactions; D006801:Humans; D015227:Lipid Peroxidation; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D020011:Protective Agents / Q000494:pharmacology*; D011759:Pyrrolidines / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D020030:Nitric Oxide Donors; C107010:O(2)-vinyl-1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate; D020011:Protective Agents; D011759:Pyrrolidines; D017382:Reactive Oxygen Species; D016718:Arachidonic Acid; D009569:Nitric Oxide; D019328:Buthionine Sulfoximine; D019392:Cytochrome P-450 CYP2E1