title: Differential effect of HIV protease inhibitors on adipogenesis: intracellular ritonavir is not sufficient to inhibit differentiation.
abstract: OBJECTIVE
  Lipodystrophy is a major side effect of HIV protease inhibitor (PI) antiretroviral therapy. It has been shown that protease inhibitors interfere in vitro with adipocyte differentiation. However, there is no evidence that PIs accumulate into preadipocytes and adipocytes and that intra-cellular accumulation is sufficient to alter differentiation. We assessed the effect of six different PIs on the differentiation of cells from four clonal lines. We also studied the capacity of ritonavir to accumulate both into drug-sensitive and drug-resistant cultured adipocytes.
  
  
  METHODS
  Adipocyte differentiation of mouse 3T3-F442A, 3T3-L1 and Ob1771 cells as well as embryonic stem cells were investigated at pharmacological concentrations of indinavir, saquinavir, ritonavir, amprenavir, nelfinavir and lopinavir. We used a sensitive ELISA to determine intracellular concentration of ritonavir from 3T3-L1 and Ob1771 preadipocytes.
  
  
  RESULTS
  Nelfinavir and lopinavir inhibited adipocyte differentiation whereas amprenavir was ineffective. Indinavir, saquinavir and ritonavir inhibited differentiation of 3T3-L1 and 3T3-F442A cells but did not alter differentiation of either Ob1771 or embryonic stem cells. We showed that ritonavir accumulated in preadipocytes and fully differentiated 3T3-L1 adipocytes as a function of its extracellular concentration. Although Ob1771 cells were resistant and 3T3-L1 cells were sensitive to ritonavir, the drug accumulated to similar levels in both cases.
  
  
  CONCLUSIONS
  Protease inhibitors inhibit adipocyte differentiation depending on the cell model used. We showed for the first time that ritonavir accumulates into preadipocytes and adipocytes, suggesting a direct effect on intracellular targets. However, intracellular accumulation was clearly not sufficient as Ob1771 cells remained resistant to the inhibitory effect of ritonavir.
authors.affiliation: Institute of Signalling, Development Biology and Cancer Research, Biochemistry Centre, UMR 6543 CNRS, Faculty of Science, Nice, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Vernochet
authors.forename: Stéphane
authors.initials: S
authors.lastname: Azoulay
authors.forename: Danièle
authors.initials: D
authors.lastname: Duval
authors.forename: Roger
authors.initials: R
authors.lastname: Guedj
authors.forename: Gérard
authors.initials: G
authors.lastname: Ailhaud
authors.forename: Christian
authors.initials: C
authors.lastname: Dani
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D002219:Carbamates; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005663:Furans; D017320:HIV Protease Inhibitors / Q000378:metabolism*; D019469:Indinavir / Q000494:pharmacology; D061466:Lopinavir; D051379:Mice; D008815:Mice, Inbred Strains; D019888:Nelfinavir / Q000494:pharmacology; D011744:Pyrimidinones / Q000494:pharmacology; D019438:Ritonavir / Q000493:pharmacokinetics / Q000494:pharmacology*; D019258:Saquinavir / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D002219:Carbamates; D005663:Furans; D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D013449:Sulfonamides; D061466:Lopinavir; C095108:amprenavir; D019469:Indinavir; D019888:Nelfinavir; D019258:Saquinavir; D019438:Ritonavir