title: Modulation of liver canalicular transport processes by the tyrosine-kinase inhibitor genistein: implications of genistein metabolism in the rat.
abstract: Rat liver cells express the multispecific organic anion transporter (cmoat, cmrp, mrp2) and P-glycoprotein (Pgp) in their canalicular membranes, proteins that are homologous to the multidrug-resistance related protein (MRP) and multidrug resistance (MDR) gene products in multidrug resistant tumor cells. We tested whether genistein, a modulator of drug resistance in tumor cells, affects biliary secretion of substrates of canalicular multispecific organic anion transporter (cmoat) (glucuronides of bilirubin and rhodamine, glutathione conjugate of bromsulphthalein) and of P-glycoprotein (Pgp) (rhodamine), respectively. Using the isolated perfused rat liver of control Wistar rats (TR+) and of a mutant strain (TR-) that expresses Pgp but not cmoat, we show that genistein effectively inhibits the secretion of anionic substrates of cmoat in Wistar rats but stimulates secretion of cationic rhodamine in TR- rats. Genistein is subject to glucuronidation and sulfatation and secretion of genistein and its metabolites stimulates bile flow in Wistar rats, but secretion is nearly absent in TR- rats. Because genistein and its metabolites are substrates for cmoat, inhibition of anion secretion by genistein is partially explained by competition for this transporter. Genistein is also a substrate of uridindiphosphate (UDP)-glucuronyltransferase isoenzyme(s). Inhibition of glucuronidation reduces the availability of bilirubin and rhodamine glucuronates for transport via cmoat, but unconjugated cationic rhodamine becomes available for transport via Pgp at an increased cellular concentration. Daidzein, a genistein analogue with no effect on protein tyrosine kinase (PTK) shows Similar effects on secretion of organic anions and cations supporting the conclusion that genistein affects transport in liver mainly through competition with other substrates at the sites of glucuronidation and transport via cmoat.
authors.affiliation: Institute of Pharmaceutical Chemistry, Vienna, Austria.
authors.forename: W
authors.initials: W
authors.lastname: Jäger
authors.forename: O
authors.initials: O
authors.lastname: Winter
authors.forename: B
authors.initials: B
authors.lastname: Halper
authors.forename: A
authors.initials: A
authors.lastname: Salamon
authors.forename: M
authors.initials: M
authors.lastname: Sartori
authors.forename: L
authors.initials: L
authors.lastname: Gajdzik
authors.forename: G
authors.initials: G
authors.lastname: Hamilton
authors.forename: G
authors.initials: G
authors.lastname: Theyer
authors.forename: J
authors.initials: J
authors.lastname: Graf
authors.forename: T
authors.initials: T
authors.lastname: Thalhammer
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D027321:Anion Transport Proteins; D001646:Bile / Q000378:metabolism; D001663:Bilirubin / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D019833:Genistein / Q000378:metabolism / Q000494:pharmacology*; D014453:Glucuronosyltransferase / Q000378:metabolism; D066298:In Vitro Techniques; D007529:Isoflavones / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009154:Mutation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D051381:Rats; D017208:Rats, Wistar; D012235:Rhodamines / Q000378:metabolism; D012457:Salicylamides / Q000494:pharmacology; D013448:Sulfobromophthalein / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D027321:Anion Transport Proteins; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D007529:Isoflavones; D012235:Rhodamines; D012457:Salicylamides; D013448:Sulfobromophthalein; C004742:daidzein; D019833:Genistein; D014453:Glucuronosyltransferase; D011505:Protein-Tyrosine Kinases; C031060:salicylamide; D001663:Bilirubin