title: The effect of glutathione on the ATPase activity of MRP1 in its natural membranes.
abstract: The transport mechanism by which the multidrug resistance protein 1 (MRP1) effluxes cytotoxic agents out of cells is still not completely understood. However, the cellular antioxidant glutathione (GSH) has been shown to have an important role in MRP1-mediated drug transport. In this study we show that GSH stimulates the ATPase activity of MRP1 in a natural plasma membrane environment. This stimulation was dose-dependent up to 5 mM. The MRP1 substrates vincristine and daunorubicin do not induce MRP1 ATPase activity. In addition, the effect of GSH on the MRP1 ATPase activity is not increased by daunorubicin or by vincristine. In contrast, a GSH conjugate of daunorubicin (WP811) does induce the ATPase activity of MRP1. In the presence of GSH the effect of WP811 was not significantly increased. Finally, (iso)flavonoid-induced MRP1 ATPase activity is not synergistically increased by the presence of GSH. In conclusion, we show that GSH has no apparent influence on the ATPase reaction induced by several MRP1 substrates and/or modulators. The subclasses of molecules had different effects on the MRP1 ATPase activity, which supports the existence of different drug binding sites.
authors.affiliation: Department of Medical Oncology, Academisch Ziekenhuis Vrije Universiteit, Room BR 232, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands.
authors.forename: J H
authors.initials: JH
authors.lastname: Hooijberg
authors.forename: H M
authors.initials: HM
authors.lastname: Pinedo
authors.forename: C
authors.initials: C
authors.lastname: Vrasdonk
authors.forename: W
authors.initials: W
authors.lastname: Priebe
authors.forename: J
authors.initials: J
authors.lastname: Lankelma
authors.forename: H J
authors.initials: HJ
authors.lastname: Broxterman
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003630:Daunorubicin / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000494:pharmacology
chemical_list: D000251:Adenosine Triphosphatases; D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D004268:DNA-Binding Proteins; D003630:Daunorubicin; D005419:Flavonoids; D005978:Glutathione; D008565:Membrane Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D014750:Vincristine; C078444:MSH3 protein, human; C421109:multidrug resistance-associated protein 1