title: Identification of an organic anion transport system in the human colon carcinoma cell line HT29 clone 19A.
abstract: The human colon carcinoma cell line HT29 c1.19A was studied for organic anion transporter activity by determining intracellular fluo-3 and fura-red accumulation and by measuring fluo-3 efflux. Modulators of organic anion transport systems were used to identify the transporters that are involved in dye extrusion. Addition of probenecid to the dye-loading medium, containing 10 microM fluo-3/AM and fura-red/AM, resulted in a dose-dependent increase in fluo-3 and fura-red accumulation in the cells. The increase in fluo-3 accumulation in the cells in the presence of probenecid was explained by the inhibitory effect of this compound on fluo-3 efflux. Fluo-3 efflux from the cells was also inhibited by sulfinpyrazone, another inhibitor of organic anion transport. Substrates of renal probenecid-sensitive organic anion exchange mechanisms as well as modulators of multidrug resistance associated protein (MRP) activity did not influence fluo-3 extrusion rates. However, reducing intracellular ATP contents completely blocked fluo-3 extrusion. Moreover, MK571, an inhibitor of MRP, significantly stimulated dye accumulation, whereas inhibitors of the multidrug resistance gene (MDR1) product Pglycoprotein, cyclosporin A and verapamil, did not. As probenecid inhibits fluo-3 efflux across the apical membrane of cells grown on permeable supports, we conclude that a probenecid-sensitive organic anion transporter is present in the apical membrane of HT29 c1.19A cells. This organic anion transport system differs from MDRI and MRP2.
authors.affiliation: Surgical Laboratory, Academic Medical Center, Amsterdam, The Netherlands. s.l.abrahamse@amc.uva.nl
authors.forename: S L
authors.initials: SL
authors.lastname: Abrahamse
authors.forename: G
authors.initials: G
authors.lastname: Rechkemmer
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000255:Adenosine Triphosphate / Q000378:metabolism; D000814:Aniline Compounds / Q000378:metabolism; D000838:Anions; D001572:Benzofurans / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism*; D017097:Electric Impedance; D005456:Fluorescent Dyes / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D007093:Imidazoles / Q000378:metabolism; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D011339:Probenecid / Q000494:pharmacology; D014966:Xanthenes / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000814:Aniline Compounds; D000838:Anions; D001572:Benzofurans; D002352:Carrier Proteins; D005456:Fluorescent Dyes; D007093:Imidazoles; D014966:Xanthenes; C082877:fura red; C059715:Fluo-3; D000255:Adenosine Triphosphate; D011339:Probenecid