title: Functional characterization of the organic cation transporters (OCTs) in human airway pulmonary epithelial cells.
abstract: Organic cation transporters (OCT1-3) mediate the transport of organic cations including inhaled drugs across the cell membrane, although their role in lung epithelium hasn't been well understood yet. We address here the expression and functional activity of OCT1-3 in human airway epithelial cells A549, Calu-3 and NCl-H441. Kinetic and inhibition analyses, employing [(3)H]1-methyl-4-phenylpyridinium (MPP+) as substrate, and the compounds quinidine, prostaglandine E2 (PGE2) and corticosterone as preferential inhibitors of OCT1, OCT2, and OCT3, respectively, have been performed. A549 cells present a robust MPP+ uptake mediated by one high-affinity component (Km~50μM) which is identifiable with OCT3. Corticosterone, indeed, completely inhibits MPP+ transport, while quinidine and PGE2 are inactive and SLC22A3/OCT3 silencing with siRNA markedly lowers MPP+ uptake. Conversely, Calu-3 exhibits both a high (Km<20μM) and a low affinity (Km>0.6mM) transport components, referable to OCT3 and OCT1, respectively, as demonstrated by the inhibition analysis performed at proper substrate concentrations and confirmed by the use of specific siRNA. These transporters are active also when cells are grown under air-liquid interface (ALI) conditions. Only a very modest saturable MPP+ uptake is measurable in NCl-H441 cells and the inhibitory effect of quinidine points to OCT1 as the subtype functionally involved in this model. Finally, the characterization of MPP+ transport in human bronchial BEAS-2B cells suggests that OCT1 and OCT3 are operative. These findings could help to identify in vitro models to be employed for studies concerning the specific involvement of each transporter in drug transportation.
authors.affiliation: Dept. of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Ingoglia
authors.affiliation: Dept. of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy.
authors.forename: Rossana
authors.initials: R
authors.lastname: Visigalli
authors.affiliation: Dept. of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy.
authors.forename: Bianca Maria
authors.initials: BM
authors.lastname: Rotoli
authors.affiliation: Dept. of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy.
authors.forename: Amelia
authors.initials: A
authors.lastname: Barilli
authors.affiliation: Preclinical Pharmacokinetics, Biochemistry & Metabolism Dept., Chiesi Farmaceutici, Largo F. Belloli 11/A, 43122 Parma, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Riccardi
authors.affiliation: Preclinical Pharmacokinetics, Biochemistry & Metabolism Dept., Chiesi Farmaceutici, Largo F. Belloli 11/A, 43122 Parma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Puccini
authors.affiliation: Dept. of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy. Electronic address: valeria.dallasta@unipr.it.
authors.forename: Valeria
authors.initials: V
authors.lastname: Dall'Asta
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000378:metabolism / Q000493:pharmacokinetics; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D003345:Corticosterone / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008168:Lung / Q000166:cytology; D027701:Organic Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D027702:Organic Cation Transporter 1 / Q000235:genetics / Q000378:metabolism*; D000075102:Organic Cation Transporter 2; D011802:Quinidine / Q000494:pharmacology; D034622:RNA Interference; D013997:Time Factors; D000099254:Organic Cation Transporter 3
chemical_list: D015655:1-Methyl-4-phenylpyridinium; D003345:Corticosterone; D015232:Dinoprostone; D027701:Organic Cation Transport Proteins; D027702:Organic Cation Transporter 1; D000075102:Organic Cation Transporter 2; D011802:Quinidine; D000099254:Organic Cation Transporter 3; C491013:SLC22A2 protein, human
keywords: Cationic drug transporters; OCT1; OCT2; OCT3; Organic cation transporters; Pulmonary epithelium