title: Role of glutathione in the export of compounds from cells by the multidrug-resistance-associated protein.
abstract: Multidrug-resistance-associated protein (MRP) is a plasma membrane glycoprotein that can confer multidrug resistance (MDR) by lowering intracellular drug concentration. Here we demonstrate that depletion of intracellular glutathione by DL-buthionine (S,R)-sulfoximine results in a complete reversal of resistance to doxorubicin, daunorubicin, vincristine, and VP-16 in lung carcinoma cells transfected with a MRP cDNA expression vector. Glutathione depletion had less effect on MDR in cells transfected with MDR1 cDNA encoding P-glycoprotein and did not increase the passive uptake of daunorubicin by cells, indicating that the decrease of MRP-mediated MDR was not due to nonspecific membrane damage. Glutathione depletion resulted in a decreased efflux of daunorubicin from MRP-transfected cells, but not from MDR1-transfected cells, suggesting that glutathione is specifically required for the export of drugs from cells by MRP. We also show that MRP increases the export of glutathione from the cell and this increased export is further elevated in the presence of arsenite. Our results support the hypothesis that MRP functions as a glutathione S-conjugate carrier.
authors.affiliation: Division of Molecular Biology, Netherlands Cancer Institute, Amsterdam.
authors.forename: G J
authors.initials: GJ
authors.lastname: Zaman
authors.forename: J
authors.initials: J
authors.lastname: Lankelma
authors.forename: O
authors.initials: O
authors.lastname: van Tellingen
authors.forename: J
authors.initials: J
authors.lastname: Beijnen
authors.forename: H
authors.initials: H
authors.lastname: Dekker
authors.forename: C
authors.initials: C
authors.lastname: Paulusma
authors.forename: R P
authors.initials: RP
authors.lastname: Oude Elferink
authors.forename: F
authors.initials: F
authors.lastname: Baas
authors.forename: P
authors.initials: P
authors.lastname: Borst
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000633:toxicity*; D018053:Arsenites / Q000494:pharmacology; D019328:Buthionine Sulfoximine; D002289:Carcinoma, Non-Small-Cell Lung; D002455:Cell Division; D003545:Cysteine / Q000378:metabolism; D018432:Drug Resistance, Multiple; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008175:Lung Neoplasms; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives* / Q000494:pharmacology; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D018053:Arsenites; D019328:Buthionine Sulfoximine; D003545:Cysteine; D005978:Glutathione; D008717:Methionine Sulfoximine; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011994:Recombinant Proteins; C015001:arsenite