title: Tumor cell responses to a novel glutathione S-transferase-activated nitric oxide-releasing prodrug.
abstract: We have used structure-based design techniques to introduce the drug O(2)-[2,4-dinitro-5-(N-methyl-N-4-carboxyphenylamino) phenyl] 1-N,N-dimethylamino)diazen-1-ium-1,2-diolate (PABA/NO), which is efficiently metabolized to potentially cytolytic nitric oxide by the pi isoform of glutathione S-transferase, an enzyme expressed at high levels in many tumors. We have used mouse embryo fibroblasts (MEFs) null for GSTpi (GSTpi(-/-)) to show that the absence of GSTpi results in a decreased sensitivity to PABA/NO. Cytotoxicity of PABA/NO was also examined in a mouse skin fibroblast (NIH3T3) cell line that was stably transfected with GSTpi and/or various combinations of gamma-glutamyl cysteine synthetase and the ATP-binding cassette transporter MRP1. Overexpression of MRP1 conferred the most significant degree of resistance, and in vitro transport studies confirmed that a GSTpi-activated metabolite of PABA/NO was effluxed by MRP1 in a GSH-dependent manner. Additional studies showed that in the absence of MRP1, PABA/NO activated the extracellular-regulated and stress-activated protein kinases ERK, c-Jun NH(2)-terminal kinase (JNK), and p38. Selective inhibition studies showed that the activation of JNK and p38 were critical to the cytotoxic effects of PABA/NO. Finally, PABA/NO produced antitumor effects in a human ovarian cancer model grown in SCID mice.
authors.affiliation: Department of Pharmacology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Findlay
authors.forename: Danyelle M
authors.initials: DM
authors.lastname: Townsend
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Saavedra
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Buzard
authors.forename: Michael L
authors.initials: ML
authors.lastname: Citro
authors.forename: Larry K
authors.initials: LK
authors.lastname: Keefer
authors.forename: Xinhua
authors.initials: X
authors.lastname: Ji
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Tew
mesh_terms: D016475:3T3 Cells; D010129:4-Aminobenzoic Acid / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001391:Azo Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D017997:Leukotriene C4 / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D011355:Prodrugs / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases; D062366:para-Aminobenzoates
chemical_list: D010129:4-Aminobenzoic Acid; D001391:Azo Compounds; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D007527:Isoenzymes; D048031:JNK Mitogen-Activated Protein Kinases; D017997:Leukotriene C4; D020928:Mitogen-Activated Protein Kinases; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009569:Nitric Oxide; D020030:Nitric Oxide Donors; D010879:Piperazines; D011355:Prodrugs; D048051:p38 Mitogen-Activated Protein Kinases; D062366:para-Aminobenzoates; C485370:O(2)-(2,4-dinitro-5-(N-methyl-N-4-carboxyphenylamino)phenyl 1-N,N-dimethylamino)diazen-1-ium-1,2-diolate; C474958:O(2)-(2,4-dinitrophenyl) 1-((4-ethoxycarbonyl)piperazin-1-yl)diazen-1-ium-1,2-diolate; C496557:Gstp1 protein, mouse