title: P-Glycoprotein and transporter MRP1 reduce HIV protease inhibitor uptake in CD4 cells: potential for accelerated viral drug resistance?
abstract: BACKGROUND
  The multidrug transporters P-glycoprotein (P-gp) and MRP1 are functionally expressed in several subclasses of lymphocytes. HIV-1 protease inhibitors interact with both; consequently the transporters could reduce the local concentration of HIV-1 protease inhibitors and, thus, influence the selection of viral mutants.
  
  
  OBJECTIVE
  To study the effect of the expression of P-gp and MRP1 on the transport and accumulation of HIV-1 protease inhibitors in human lymphocytes and to study the effects of specific P-gp and MRP1 inhibitors.
  
  
  METHODS
  The initial rate and the steady-state intracellular accumulation of radiolabelled ritonavir, indinavir, saquinavir and nelfinavir was measured in three human lymphocyte cell lines: control CEM cells, CEM-MDR cells, which express 30-fold more P-gp than CEM cells, and CEM-MRP cells, which express fivefold more MRP1 protein than CEM cells. The effect of specific inhibitors of P-gp (GF 120918) and MRP1 (MK 571) was also examined.
  
  
  RESULTS
  Compared with CEM cells, the initial rates of uptake and the steady-state intracellular concentrations of all protease inhibitors are significantly reduced in CEM-MDR cells. The intracellular concentrations of the protease inhibitors are increased upon co-administration with GF 120918, in some cases to levels approaching those in CEM cells. The intracellular concentrations of the protease inhibitors are also significantly reduced in CEM-MRP cells. Co-administration with MK -571 can partially overcome these effects.
  
  
  CONCLUSIONS
  The overexpression of multidrug transporters significantly reduces the accumulation of protease inhibitors at this major site of virus replication, which, potentially, could accelerate the acquisition of viral resistance. Targeted inhibition of P-gp may represent an important strategy by which this problem can be overcome.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK.
authors.forename: K
authors.initials: K
authors.lastname: Jones
authors.forename: P G
authors.initials: PG
authors.lastname: Bray
authors.forename: S H
authors.initials: SH
authors.lastname: Khoo
authors.forename: R A
authors.initials: RA
authors.lastname: Davey
authors.forename: E R
authors.initials: ER
authors.lastname: Meaden
authors.forename: S A
authors.initials: SA
authors.lastname: Ward
authors.forename: D J
authors.initials: DJ
authors.lastname: Back
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism* / Q000821:virology; D002460:Cell Line; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D017320:HIV Protease Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D019469:Indinavir / Q000378:metabolism / Q000494:pharmacology; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D019888:Nelfinavir / Q000378:metabolism / Q000494:pharmacology; D019438:Ritonavir / Q000378:metabolism / Q000494:pharmacology; D019258:Saquinavir / Q000378:metabolism / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D017320:HIV Protease Inhibitors; D019469:Indinavir; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D019888:Nelfinavir; D019438:Ritonavir; D019258:Saquinavir