title: Pentoxifylline and other protein kinase C inhibitors down-regulate HIV-LTR NF-kappa B induced gene expression.
abstract: BACKGROUND
  This investigation deals with the molecular mechanism of anti-human immunodeficiency virus type 1 (HIV-1) action of pentoxifylline (PTX) [1-(5'-oxohexyl)-3, 7-dimethylxanthine] a drug widely used for the treatment of conditions involving defective regional microcirculation.
  
  
  METHODS
  The inhibition by PTX of protein kinase C (PKC) or cAMP-dependent protein kinase (PKA)-mediated activation by phorbol ester (PMA) and tumor necrosis factor alpha (TNF-alpha) of HIV-1-LTR-regulated reporter gene expression was studied in human CD4+ T lymphocytes (Jurkat) and human embryo kidney cells (293-27-2). A protein kinase C is involved in activation of NF-kappa B in whole cells, identified by using inhibitors specific for PKC- or PKA-catalyzed NF-kappa B activation in whole cell and cell-free systems.
  
  
  RESULTS
  PTX inhibited PKC- or PKA-catalyzed activation of NF-kappa B in cytoplasmic extracts from unstimulated Jurkat or 293-27-2 cells, but not interaction of preactivated NF-kappa B with its motifs. Calphostin C, a specific inhibitor of PKC, inhibited NF-kappa B activation and HIV-1 LTR-driven reporter gene expression in both PMA- and TNF-alpha-treated cells. In contrast, although H88 specifically inhibited PKA activity in the cell-free extract, it did not affect NF-kappa B action in PMA- or TNF-alpha-treated cells.
  
  
  CONCLUSIONS
  The mechanism of inhibitory action of PTX on virus replication and NF-kappa B-induced transactivation of HIV-1 gene expression has been elucidated as due to blocking PKC-dependent PMA- or TNF-alpha-induced activation of NF-kappa B in Jurkat and 293-27-2 cells. Other protein kinase inhibitors may be useful in down regulating transcription of HIV-1 provirus and thereby virus replication in HIV-infected patients.
authors.affiliation: Division of Cell Growth and Regulation, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
authors.forename: D K
authors.initials: DK
authors.lastname: Biswas
authors.forename: C M
authors.initials: CM
authors.lastname: Ahlers
authors.forename: B J
authors.initials: BJ
authors.lastname: Dezube
authors.forename: A B
authors.initials: AB
authors.lastname: Pardee
mesh_terms: D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D016325:HIV Long Terminal Repeat / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D010431:Pentoxifylline / Q000378:metabolism / Q000494:pharmacology*; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D016328:NF-kappa B; D009281:Naphthalenes; D010703:Phorbol Esters; D014409:Tumor Necrosis Factor-alpha; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C058819:calphostin C; D010431:Pentoxifylline