title: Suppression of preadipocyte differentiation and promotion of adipocyte death by HIV protease inhibitors.
abstract: Many human immunodeficiency virus (HIV)-infected patients taking combination antiretroviral therapy that includes HIV protease inhibitors experience atrophy of peripheral subcutaneous adipose tissue. We investigated the effects of HIV protease inhibitors on adipogenesis and adipocyte survival using the 3T3-L1 preadipocyte cell line. Several HIV protease inhibitors were found either to inhibit preadipocyte differentiation or to promote adipocyte cell death. One protease inhibitor, nelfinavir, elicited both of these effects strongly. When induced to differentiate in the presence of nelfinavir, 3T3-L1 preadipocytes failed to accumulate cytoplasmic triacylglycerol and failed to express normal levels of the adipogenic transcription factors CCAAT/enhancer-binding protein alpha and peroxisome proliferator-activated receptor gamma. The level of the proteolytically processed, active 68-kDa form of sterol regulatory element-binding protein-1, a transcription factor known to promote lipogenic gene expression, also was reduced markedly in nelfinavir-treated cells, whereas the level of the 125-kDa precursor form of this protein was unaffected. The inhibitory effect of nelfinavir occurred subsequent to critical early events in preadipocyte differentiation, expression of CCAAT/enhancer-binding protein beta and completion of the mitotic clonal expansion phase, because these events were unaffected by nelfinavir treatment. In addition, nelfinavir treatment of fully differentiated 3T3-L1 adipocytes resulted in DNA strand cleavage and severe loss of cell viability. In contrast, cell proliferation and viability of preadipocytes were unaffected by nelfinavir treatment. Thus, molecular or cellular changes that occur during acquisition of the adipocyte phenotype promote susceptibility to nelfinavir-induced cell death. When considered together, these results suggest that nelfinavir may promote adipose tissue atrophy by compromising adipocyte viability and preventing replacement of lost adipocytes by inhibiting preadipocyte differentiation.
authors.affiliation: Departments of Biological Chemistry, Pharmacology and Molecular Sciences, and Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. dowellp@welchlink.welch.jhu.edu
authors.forename: P
authors.initials: P
authors.lastname: Dowell
authors.forename: C
authors.initials: C
authors.lastname: Flexner
authors.forename: P O
authors.initials: PO
authors.lastname: Kwiterovich
authors.forename: M D
authors.initials: MD
authors.lastname: Lane
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D020287:In Situ Nick-End Labeling; D051379:Mice; D008938:Mitosis / Q000187:drug effects; D019888:Nelfinavir / Q000494:pharmacology; D013234:Stem Cells / Q000187:drug effects* / Q000502:physiology; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D014280:Triglycerides / Q000378:metabolism
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D017320:HIV Protease Inhibitors; C497388:Srebf1 protein, mouse; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D014280:Triglycerides; D019888:Nelfinavir