title: Effluxing ABC transporters in human corneal epithelium.
abstract: ATP-binding cassette (ABC) transporters are able to efflux their substrate drugs from the cells. We compared expression of efflux proteins in normal human corneal epithelial tissue, primary human corneal epithelial cells (HCEpiC), and corneal epithelial cell culture model (HCE model) based on human immortal cell line. Expression of multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1-6 (MRP1-6) and breast cancer resistance protein (BCRP) was studied using quantitative RT-PCR, Western blot, and immunohistochemistry. Only MRP1, MRP5, and BCRP were expressed in the freshly excised human corneal epithelial tissue. Expression of MRP1 and MRP5 was localized predominantly in the basal cells of the central cornea and limbus. Functional efflux activity was shown in the cell models, but they showed over-expression of most efflux transporters compared to that of normal corneal epithelium. In conclusion, MRP1, MRP5, and BCRP are expressed in the corneal epithelium, but MDR1, MRP2, MRP3, MRP4, and MRP6 are not significantly expressed. HCE cell model and commercially available primary cells deviate from this expression profile.
authors.affiliation: Centre for Drug Research, University of Helsinki, Helsinki, Finland.
authors.forename: Kati-Sisko
authors.initials: KS
authors.lastname: Vellonen
authors.forename: Eliisa
authors.initials: E
authors.lastname: Mannermaa
authors.forename: Helen
authors.initials: H
authors.lastname: Turner
authors.forename: Marika
authors.initials: M
authors.lastname: Häkli
authors.forename: J Mario
authors.initials: JM
authors.lastname: Wolosin
authors.forename: Timo
authors.initials: T
authors.lastname: Tervo
authors.forename: Paavo
authors.initials: P
authors.lastname: Honkakoski
authors.forename: Arto
authors.initials: A
authors.lastname: Urtti
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism; D019573:Epithelium, Corneal / Q000378:metabolism*; D005452:Fluoresceins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018528:ATP-Binding Cassette Transporters; D005452:Fluoresceins; D012333:RNA, Messenger; C053897:5(6)-carboxy-2',7'-dichlorofluorescein; D002118:Calcium