title: Tumor necrosis factor alpha increases P-glycoprotein expression in a BME-UV in vitro model of mammary epithelial cells.
abstract: P-glycoprotein is an efflux pump belonging to the ATP-binding cassette super-family that influences the bioavailability and disposition of many drugs. Mammary epithelial cells express various drug transporters including P-glycoprotein, albeit at low level during lactation. During inflammatory reactions, which can be associated with changes in epithelial barrier functions, pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) are elevated in milk and serum. In this study, the role of TNF-α in the regulation of P-glycoprotein was determined in cultured BME-UV cells, an immortalized bovine mammary epithelial cell line. The protein production of P-glycoprotein and mRNA expression of bABCB1, the gene encoding P-glycoprotein, were increased after 24 h of TNF-α exposure. The highest observed effects for TNF-α on the regulation of P-glycoprotein was after 72 h of exposure. Protein and mRNA expression also increased significantly after 120 h of TNF-α exposure, but was lower than the level observed in the cells exposed to TNF-α for 72 h. The apical to basolateral flux of digoxin, a P-glycoprotein substrate, was decreased in the TNF-α-exposed epithelium. This effect was reversed when verapamil or ketoconazole, compounds known to interact with P-glycoprotein, were added together with digoxin into the donor compartment. Probenecid, a compound known to interact with organic anion transporters, but not P-glycoprotein, did not increase the flux of digoxin. This model has important implications for understanding the barrier function of the mammary epithelium and provides insight into the role of P-glycoprotein in the accumulation and/or removal of xenobiotics from milk and/or plasma.
authors.affiliation: Department of Clinical Sciences, Kansas State University, Manhattan, KS 66505, USA.
authors.forename: Mohammad M
authors.initials: MM
authors.lastname: Al-Bataineh
authors.forename: Deon
authors.initials: D
authors.lastname: van der Merwe
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Schultz
authors.forename: Ronette
authors.initials: R
authors.lastname: Gehring
mesh_terms: D058888:14-alpha Demethylase Inhibitors / Q000494:pharmacology; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002417:Cattle; D002461:Cell Line, Transformed; D002463:Cell Membrane Permeability / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism*; D004077:Digoxin / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D007249:Inflammation / Q000378:metabolism; D007654:Ketoconazole / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D058888:14-alpha Demethylase Inhibitors; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D002121:Calcium Channel Blockers; D016207:Cytokines; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D004077:Digoxin; D014700:Verapamil; D007654:Ketoconazole