16HBE14o- human bronchial epithelial cell layers express P-glycoprotein, lung resistance-related protein, and caveolin-1.
OBJECTIVE
To study the expression of P-glycoprotein (P-gp), lung resistance-related protein (LRP), and caveolin-1 (cav-1) in the human bronchial epithelial cell line 16HBE14o-.


METHODS
The presence of P-gp, LRP, and cav-1 in 16HBE14o- cell layers was evaluated using immunocytochemical staining and visualization with confocal laser scanning microscopy (CLSM). Functionality of P-gp was determined by bidirectional transport of rhodamine-123 with and without a P-gp inhibitor, verapamil. Caveolae were visualized using transmission electron microscopy (TEM). Flux of fluorescein-Na was also studied as a paracellular transport marker.


RESULTS
Immunocytochemical staining showed expression of P-gp localized at the apical membrane of 16HBE14o- cell layers. The flux of rhodamine 123 across cell layers exhibited a greater Papp value for the secretory (i.e., basolateral-to-apical) direction. This asymmetry disappeared in the presence of verapamil. CLSM provided evidence for the expression of LRP and cav-1. TEM further showed typically shaped caveolae at the apical and basolateral membranes.


CONCLUSIONS
Cell layers of 16HBE14o- express drug transport systems that are also present in the human bronchus in vivo, indicating that the 16HBE14o- cell line may be a suitable candidate for an in vitro model for mechanistic studies of drug transport processes involved in the smaller airways.
Ehrhardt
Carsten
C
Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, 66123 Saarbrücken, Germany. c.ehrhardt@mx.uni-saarland.de
Kneuer
Carsten
C
Laue
Michael
M
Schaefer
Ulrich Friedrich
UF
Kim
Kwang-Jin
KJ
Lehr
Claus-Michael
CM
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001980:Bronchi / Q000166:cytology* / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism*; D011817:Rabbits; D020394:Vault Ribonucleoprotein Particles / Q000378:metabolism*; D000099187:Major Vault Protein
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D051242:Caveolin 1; D022461:Caveolins; D009363:Neoplasm Proteins; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein; C495540:CAV1 protein, human