title: P-gp efflux pump inhibition potential of common environmental contaminants determined in vitro.
abstract: Across different species, cellular efflux pumps such as P-glycoprotein (P-gp; also termed multidrug resistance protein 1 [MDR1]) serve as a first line of defense by transporting toxic xenobiotics out of the cell. This mechanism is also active in aquatic organisms such as mussels, fish, and their larvae. Modulation of this resistance mechanism by chemical agents occurring in the environment could result in either higher or lower internal concentrations of toxic or endogenous compounds in cells. The aim of the present study was to explore and quantify the inhibition of the P-gp efflux pumps by several ubiquitous aquatic contaminants. The calcein-acetoxymethyl ester (calcein-AM) assay commonly used in pharmacological research was established with P-gp-overexpressing Madin-Darby canine kidney cells (MDCKII-MDR1) in a 96-well plate, avoiding extra washing, centrifugation, and lysis steps. This calcein-AM-based P-gp cellular efflux pump inhibition assay (CEPIA) was used to study the inhibition by commonly occurring environmental contaminants. Among others, the compounds pentachlorophenol, perfluorooctane sulfonate, and perfluorooctanoate strongly inhibited the P-gp-mediated efflux of calcein-AM while the chloninated alkanes did not seem to interact with the transporter. The fact that common pollutants can be potent modulators of the efflux transporters is a motive to further study whether this increases the toxicity of other contaminants present in the same matrices.
authors.affiliation: Division of Toxicology, Wageningen University, Wageningen, The Netherlands; Nutrition and Toxicology Unit, Department of the Environment and Agro-Biotechnologies, Gabriel Lippmann Center for Public Research, Belvaux, Luxembourg.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Georgantzopoulou
authors.forename: Ewa
authors.initials: E
authors.lastname: Skoczyńska
authors.forename: Johannes H J
authors.initials: JH
authors.lastname: Van den Berg
authors.forename: Walter
authors.initials: W
authors.lastname: Brand
authors.forename: Sylvain
authors.initials: S
authors.lastname: Legay
authors.forename: Sebastian G
authors.initials: SG
authors.lastname: Klein
authors.forename: Ivonne M C M
authors.initials: IM
authors.lastname: Rietjens
authors.forename: Albertinka J
authors.initials: AJ
authors.lastname: Murk
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001681:Biological Assay; D004285:Dogs; D004785:Environmental Pollutants / Q000633:toxicity*; D005452:Fluoresceins / Q000378:metabolism*; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D014162:Transfection
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004785:Environmental Pollutants; D005452:Fluoresceins; C085925:calcein AM
keywords: Calcein-AM; Efflux pumps; P-glycoprotein; Pentachlorophenol; multixenobiotic resistance; perfluorooctane sulfonate