TY - JOUR T1 - Transporter Studies with the 3-<em>O</em>-Sulfate Conjugate of 17α-Ethinylestradiol: Assessment of Human Kidney Drug Transporters JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 1064 LP - 1071 DO - 10.1124/dmd.109.031526 VL - 38 IS - 7 AU - Yong-Hae Han AU - Dennis Busler AU - Yang Hong AU - Yuan Tian AU - Cliff Chen AU - A. David Rodrigues Y1 - 2010/07/01 UR - http://dmd.aspetjournals.org/content/38/7/1064.abstract N2 - 17α-Ethinylestradiol (EE2), a synthetic and potent estrogen receptor agonist, is extensively metabolized in both intestine and liver and is largely excreted in bile and urine as the 3-O-sulfate (EE2-Sul) and 3-O-glucuronide. In the present study, EE2-Sul was evaluated as a substrate of various transporters known to be expressed in the kidney. Uptake studies were performed with human epithelial cells [human embryonic kidney (HEK)-293] that contained individually expressed organic cation transporter 2 (OCT2), organic anion transporter (OAT) forms 3 and 4, and multidrug and toxin extrusion 1 (MATE1). The transporter phenotyping studies were extended to include insect cell (Sf9) membrane vesicles that expressed multidrug resistance-associated protein 4 (MRP4) and Madin-Darby canine kidney cells that expressed OAT1. Based on the results obtained, we concluded that EE2-Sul serves as a substrate of OAT3 and OAT4, but not OCT2, OAT1, MATE1, and MRP4. First, EE2-Sul uptake was highly increased in OAT3/HEK-293 cells (versus mock/HEK-293 cells) and was inhibited by OAT3 inhibitors such as bromosulfophthalein (BSP), cimetidine, and probenecid. OAT3-mediated uptake also conformed to single-Km (Michaelis constant) kinetics (Km = 21.1 μM). Second, EE2-Sul uptake was also significantly higher in OAT4/HEK-293 cells and was inhibited by BSP, methotrexate, and probenecid. In contrast to OAT3, OAT4-dependent uptake was characterized by a two-Km model (Km1 = 1.6 μM; Km2 = 195 μM). Based on the results of this study, we hypothesize that EE2-Sul is taken up into renal proximal tubule cells by OAT3, and OAT4 plays a role in its secretion into the renal brush border lumen. Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics ER -