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Findlay VJ, Townsend DM, Saavedra JE, Buzard GS, Citro ML, Keefer LK, Ji X, Tew KD
Tumor cell responses to a novel glutathione S-transferase-activated nitric oxide-releasing prodrug
Molecular Pharmacology (2004) 65:1070-9.
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.
Publication Date: 2004-05-01.
Last updated on Thursday, April 02, 2020