title: Glutathione peptidomimetic drug modulator of multidrug resistance-associated protein.
abstract: The peptidomimetic drug gamma-glutamyl-S-(benzyl)cysteinyl-R-(-)-phenyl glycine diethyl ester (TER199) is an analog of glutathione designed to be an isozyme-specific inhibitor of GSTP1-1 protein1-1. This compound (and the de-esterified moiety) is shown to be an effective inhibitor of multidrug resistance-associated protein1 (MRP1)-mediated drug resistance. Kinetic analyses revealed that gamma-glutamyl-S-(benzyl)cysteinyl-R-(-)-phenyl glycine reversibly inhibits the transport of 2,4-dinitrophenyl-S-glutathione with a K(i) of 752 microM. TER199 reversed the accumulation deficit of daunorubicin in MRP1-transfected NIH3T3 fibroblasts and maintained intracellular levels for >2 h after daunorubicin removal. Cytotoxicity assays revealed that TER199 significantly reversed the resistance of MRP1-transfected NIH3T3 cells for vincristine, doxorubicin, etoposide, and mitoxantrone. HL-60 cells made resistant to TER199 by chronic, long-term selection had increased mRNA and protein levels of multidrug resistance-associated protein, MRP1, and gamma-glutamyl cysteine synthetase heavy and light subunits (the rate-limiting enzyme in GSH synthesis). In spite of increased gamma-glutamyl cysteine synthetase, their glutathione content was reduced approximately 35% from that of parental HL-60 cells. These cells also exhibited a drug resistance profile commensurate with the previously described MRP1 overexpressing phenotype, with resistance to Vinca alkaloids, epipodophyllotoxins, and anthracyclines; additional cross-resistance to paclitaxel (Taxol), mitoxantrone, and 5-fluorouracil was observed.
authors.affiliation: Department of Pharmacology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: O'Brien
authors.forename: B
authors.initials: B
authors.lastname: Vulevic
authors.forename: S
authors.initials: S
authors.lastname: Freer
authors.forename: J
authors.initials: J
authors.lastname: Boyd
authors.forename: H
authors.initials: H
authors.lastname: Shen
authors.forename: K D
authors.initials: KD
authors.lastname: Tew
mesh_terms: D016475:3T3 Cells; D018528:ATP-Binding Cassette Transporters / Q000187:drug effects* / Q000235:genetics; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003630:Daunorubicin / Q000378:metabolism; D004140:Dinitrophenols / Q000378:metabolism; D018432:Drug Resistance, Multiple; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D051379:Mice; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018528:ATP-Binding Cassette Transporters; D000903:Antibiotics, Antineoplastic; D003630:Daunorubicin; D004140:Dinitrophenols; D004791:Enzyme Inhibitors; D005978:Glutathione; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C096329:gamma-Glu-S-BzCys-PhGly diethyl ester