Adenosine triphosphate-dependent transport of estradiol-17beta(beta-D-glucuronide) in membrane vesicles by MDR1 expressed in insect cells

Hepatology. 1998 Nov;28(5):1371-7. doi: 10.1002/hep.510280528.


MDR1, an ABC transporter that confers multidrug resistance in tumor cells, is constitutively expressed in normal liver canalicular membrane. Human MDR1-expressing multidrug-resistant cells display increased resistance to estradiol-17beta(beta-D-glucuronide) (E217G). MDR1 substrates/modulators inhibit adenosine triphosphate (ATP)-dependent transport of E217G in the rat canalicular membrane and protect against E217G-mediated cholestasis in isolated perfused rat liver. The present studies were designed to determine if E217G is a substrate for MDR1 using a baculovirus expression system and if other estrogen glucuronides interact with MDR1. ATP-dependent transport of E217G (10 micromol/L) was linear for up to 2 minutes and yielded a rate of 45.6 pmol/min/mg protein in membrane vesicles from Sf9 cells infected with MDR1-baculovirus. This transport was saturable (Km = 62 micromol/L) and occurred into an osmotically sensitive space. ATP-dependent transport of E217G (10 micromol/L) was inhibited 63% by 10 micromol/L daunomycin, but not by 100 micromol/L S-(2,4-dinitrophenyl)glutathione (GS-DNP) (a substrate for canalicular multispecific organic anion transporter [cMOAT]). Glucuronide conjugates of the estrogen D-ring (100 micromol/L), estriol-17beta(beta-D-glucuronide) (E317G) and estriol-16(beta-D-glucuronide) (E316G), inhibited MDR1-mediated E217G transport by 58% and 35%, respectively. In contrast, noncholestatic glucuronides, estradiol-3-(beta-D-glucuronide) (E23G) or estradiol-3-sulfate-17beta(beta-D-glucuronide) (E23SO417G), had no effect. E217G neither stimulated MDR1 ATPase activity nor inhibited verapamil-stimulated ATPase activity. Infusion of 1.5 micromol/L doxorubicin or 1 micromol/L taxol protected against cholestasis induced by E316G and E317G in isolated perfused rat liver. These studies identify E217G, and probably E316G and E317G, as endogenous substrates for MDR1.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Adenosine Triphosphatases / metabolism
  • Adenosine Triphosphate / pharmacology*
  • Animals
  • Baculoviridae / genetics
  • Biological Transport, Active / drug effects
  • Cell Line
  • Cell Membrane / metabolism*
  • Cholestasis / chemically induced
  • Cholestasis / prevention & control
  • Doxorubicin / therapeutic use
  • Estradiol / analogs & derivatives*
  • Estradiol / metabolism
  • Estradiol / toxicity
  • Gene Expression*
  • Kinetics
  • Liposomes / metabolism
  • Male
  • Paclitaxel / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Spodoptera
  • Transfection


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Liposomes
  • estradiol-17 beta-glucuronide
  • Estradiol
  • Doxorubicin
  • Adenosine Triphosphate
  • Adenosine Triphosphatases
  • Paclitaxel