title: Potent interaction of flavopiridol with MRP1.
abstract: The multidrug resistance protein 1 (MRP1) is an ATP-dependent transport protein for organic anions, as well as neutral or positively charged anticancer agents. In this study we show that flavopiridol, a synthetic flavonoid currently studied in phase 1 trials for its antiproliferative characteristics, interacts with MRP1 in a potent way. Flavopiridol, as well as other (iso)flavonoids stimulate the ATPase activity of MRP1 in a dose-dependent way at low micromolar concentrations. A new specific monoclonal antibody against MRP1 (MIB6) inhibits the (iso)flavonoid-induced ATPase activity of plasma membrane vesicles prepared from the MRP1 overexpressing cell line GLC4/ADR. The accumulation of daunorubicin in GLC4/ADR cells is increased by flavopiridol and by other non-glycosylated (iso)flavonoids that interact with MRP1 ATPase activity. However, flavopiridol is the only tested compound that affects the daunorubicin accumulation when present at concentrations below 1 microM. Glycosylated (iso)flavonoids do not affect MRP1-mediated transport or ATPase activity. Finally, MRP1 overexpressing and transfected cells are resistant to flavopiridol, but not to other (iso)flavonoids tested. These findings may be of relevance for the development of anticancer therapies with flavopiridol.
authors.affiliation: Department of Medical Oncology, Academisch Ziekenhuis Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: J H
authors.initials: JH
authors.lastname: Hooijberg
authors.forename: H J
authors.initials: HJ
authors.lastname: Broxterman
authors.forename: G L
authors.initials: GL
authors.lastname: Scheffer
authors.forename: C
authors.initials: C
authors.lastname: Vrasdonk
authors.forename: M
authors.initials: M
authors.lastname: Heijn
authors.forename: M C
authors.initials: MC
authors.lastname: de Jong
authors.forename: R J
authors.initials: RJ
authors.lastname: Scheper
authors.forename: J
authors.initials: J
authors.lastname: Lankelma
authors.forename: H M
authors.initials: HM
authors.lastname: Pinedo
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D010880:Piperidines / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
chemical_list: D000251:Adenosine Triphosphatases; D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D010880:Piperidines; C078444:MSH3 protein, human; C077990:alvocidib; C421109:multidrug resistance-associated protein 1