title: Binary and ternary combinations of anti-HIV protease inhibitors: effect on gene expression and functional activity of CYP3A4 and efflux transporters.
abstract: BACKGROUND
  The purpose of this study is to identify the effect of binary and ternary combinations of anti-HIV protease inhibitors (PIs) on the expression of metabolizing enzyme (CYP3A4) and efflux transporters [multidrug resistance-associated protein 2 (MRP2), P-glycoprotein (P-gp) and breast cancer resistant protein (BCRP)] in a model intestinal cell line (LS-180).
  
  
  METHODS
  LS-180 cells were treated with various combinations of PIs (amprenavir, indinavir, saquinavir and lopinavir), and the mRNA expression levels of metabolizing enzyme and efflux transporters were measured using quantitative reverse transcription polymerase chain reaction. The alteration of gene expression was further correlated to the expression of nuclear hormone receptor PXR. Uptake of fluorescent and radioactive substrates was carried out to study the functional activity of these proteins. Cytotoxicity and adenosine triphosphate (ATP) assays were carried out to measure stress responses.
  
  
  RESULTS
  Binary and ternary combinations of PIs appeared to modulate the expression of CYP3A4, MRP2, P-gp and BCRP in a considerable manner. Unlike the individual PIs, their binary combinations showed much greater induction of metabolizing enzyme and efflux proteins. However, such pronounced induction was not observed in the presence of ternary combinations. The observed trend of altered mRNA expression was found to correlate well with the change in expression levels of PXR. The gene expression was found to correlate with activity assays. Lack of cytotoxicity and ATP activity was observed in the treatment samples, suggesting that these alterations in expression levels were probably not stress responses.
  
  
  CONCLUSIONS
  In the present study, we demonstrated that combinations of drugs can have serious consequences toward the treatment of HIV infection by altering their bioavailability and disposition.
authors.forename: Deep
authors.initials: D
authors.lastname: Kwatra
authors.forename: Aswani Dutt
authors.initials: AD
authors.lastname: Vadlapudi
authors.forename: Ramya Krishna
authors.initials: RK
authors.lastname: Vadlapatla
authors.forename: Varun
authors.initials: V
authors.lastname: Khurana
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Pal
authors.forename: Ashim K
authors.initials: AK
authors.lastname: Mitra
mesh_terms: D001682:Biological Availability; D018929:Cell Culture Techniques; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D051544:Cytochrome P-450 CYP3A / Q000235:genetics* / Q000378:metabolism; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D015870:Gene Expression / Q000187:drug effects*; D015658:HIV Infections / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D014018:Tissue Distribution
chemical_list: D017320:HIV Protease Inhibitors; D012333:RNA, Messenger; D051544:Cytochrome P-450 CYP3A