title: Ritonavir induces P-glycoprotein expression, multidrug resistance-associated protein (MRP1) expression, and drug transporter-mediated activity in a human intestinal cell line.
abstract: The present study characterized the response of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP1) to chronic ritonavir (RIT) exposure by assessing increases in P-gp and MRP1 protein expression and activity. LS-180V intestinal carcinoma cells were exposed for 3 days to 1-100 microM RIT concurrently with controls. P-gp and MRP1 protein was quantified by Western blot analysis. Cell accumulation assays, using the P-gp substrate rhodamine 123 (RH123), the P-gp/MRP1 substrate doxorubicin (DOX), and the MRP substrate carboxyfluorescein (CBF), were performed as a measure of transporter activity. RIT strongly induced P-gp and MRP1 expression (maximum 6-fold and 3-fold increases, respectively) in a concentration-dependent fashion. Following extended exposure to RIT (> 10 microM), cells accumulated < 50% of the RH123 and DOX compared with controls, whereas accumulation of CBF was decreased by 30% at 30 microM. Differences in cell accumulation of RH123 could be eliminated with verapamil (100 microM; a P-gp inhibitor), whereas decreased DOX cell accumulation was only partially reversed by verapamil. Indomethacin (100 microM; an MRP1 inhibitor) had no significant effect on RH123 or DOX accumulation, suggesting limited MRP1-mediated activity. Thus, RIT induced protein expression of P-gp and MRP1 and increased cellular drug exclusion of RH123, DOX, and CBF. Similar in vivo phenomena may occur during anti-HIV drug therapy, explaining potential decrements in therapeutic efficacy due to decreases in bioavailability or alterations in drug distribution.
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Perloff
authors.forename: L L
authors.initials: LL
authors.lastname: Von Moltke
authors.forename: J E
authors.initials: JE
authors.lastname: Marchand
authors.forename: D J
authors.initials: DJ
authors.lastname: Greenblatt
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000230:Adenocarcinoma / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D006801:Humans; D026901:Membrane Transport Proteins / Q000502:physiology*; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D019438:Ritonavir / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004268:DNA-Binding Proteins; D017320:HIV Protease Inhibitors; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D019438:Ritonavir; C078444:MSH3 protein, human; C421109:multidrug resistance-associated protein 1