title: The Effect of Albumin on MRP2 and BCRP in the Vesicular Transport Assay.
abstract: The ABC transporters multidrug resistance associated protein 2 (MRP2) and breast cancer resistance protein (BCRP) are of interest in drug development, since they affect the pharmacokinetics of several drugs. Membrane vesicle transport assays are widely used to study interactions with these proteins. Since albumin has been found to affect the kinetics of metabolic enzymes in similar membrane preparations, we investigated whether albumin affects the kinetic parameters of efflux transport. We found that albumin increased the Vmax of 5(6)-carboxy-2',7'-dichlorofluorescein (CDCF) and estradiol-17-β-D-glucuronide uptake into MRP2 vesicles in the presence of 0.1% bovine serum albumin (BSA) by 2 and 1.5-fold, respectively, while BSA increased Lucifer yellow uptake by 30% in BCRP vesicles. Km values increased slightly, but the change was not statistically significant. The effect of BSA on substrate uptake was dependent on the vesicle amount, while increasing BSA concentration did not significantly improve substrate uptake. These results indicate a minor effect of albumin on MRP2 and BCRP, but it should be considered if albumin is added to transporter assays for example as a solubilizer, since the effect may be substrate or transporter specific.
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
authors.forename: Feng
authors.initials: F
authors.lastname: Deng
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
authors.forename: Noora
authors.initials: N
authors.lastname: Sjöstedt
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Kidron
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2 / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects*; D004958:Estradiol / Q000031:analogs & derivatives / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D012709:Serum Albumin / Q000494:pharmacology*; D061987:Sf9 Cells
chemical_list: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D004958:Estradiol; D005452:Fluoresceins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D012709:Serum Albumin; C000715087:ABCC2 protein, human; C116614:ABCG2 protein, human; C053897:5(6)-carboxy-2',7'-dichlorofluorescein; C025483:estradiol-17 beta-glucuronide