title: Resistance of human multidrug resistance-associated protein 1-overexpressing lung tumor cells to the anticancer drug arsenic trioxide.
abstract: The human multidrug-resistance protein (MRP1) confers resistance to some heavy metals such as arsenic and antimony, mainly through mediating an increased cellular efflux of metal. However, it was recently suggested that arsenic, used under its trioxide derivative form as anticancer drug, is not handled by MRP1. The aim of the present study was to test this hypothesis in MRP1-overexpressing human lung tumor GLC4/Sb30 cells. Using the cytotoxicity MTT assay, GLC4/Sb30 cells were found to be 10.8-fold more resistant to arsenic trioxide (As2O3) than parental GLC4 cells. MK571, a potent inhibitor of MRP1 activity, almost totally reversed resistance of GLC4/Sb30 cells, but did not alter the sensitivity of GLC4 cells. Moreover, As2O3-loaded GLC4/Sb30 cells poorly accumulated arsenic through an increased MK571-sensitive efflux of metal. Finally, depletion of cellular glutathione levels in buthionine sulfoximine-treated GLC4/Sb30 cells was found to result in increased accumulation and reduced efflux of arsenic in cells exposed to As2O3, outlining the glutathione-dependence of MRP1-mediated transport of the metal. These results indicate that MRP1 overexpression in human tumor cells can confer resistance to As2O3, which may limit the clinical use of this anticancer drug for treatment of MRP1-positive tumors.
authors.affiliation: INSERM U456, Détoxication et Réparation Tissulaire, Faculté des Sciences Pharmaceutiques et Biologiques, 2 avenue Léon Benard, F-35043 céedex, Rennes, France. laurent.vernhet@rennes.inserm.fr
authors.forename: L
authors.initials: L
authors.lastname: Vernhet
authors.forename: N
authors.initials: N
authors.lastname: Allain
authors.forename: L
authors.initials: L
authors.lastname: Payen
authors.forename: J P
authors.initials: JP
authors.lastname: Anger
authors.forename: A
authors.initials: A
authors.lastname: Guillouzo
authors.forename: O
authors.initials: O
authors.lastname: Fardel
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000502:physiology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010087:Oxides / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D000077237:Arsenic Trioxide; D001152:Arsenicals; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010087:Oxides