AP-1 Inhibition by SR 11302 Protects Human Hepatoma HepG2 Cells from Bile Acid-Induced Cytotoxicity by Restoring the NOS-3 Expression

PLoS One. 2016 Aug 4;11(8):e0160525. doi: 10.1371/journal.pone.0160525. eCollection 2016.

Abstract

The harmful effects of bile acid accumulation occurring during cholestatic liver diseases have been associated with oxidative stress increase and endothelial nitric oxide synthase (NOS-3) expression decrease in liver cells. We have previously reported that glycochenodeoxycholic acid (GCDCA) down-regulates gene expression by increasing SP1 binding to the NOS-3 promoter in an oxidative stress dependent manner. In the present study, we aimed to investigate the role of transcription factor (TF) AP-1 on the NOS-3 deregulation during GCDCA-induced cholestasis. The cytotoxic response to GCDCA was characterized by 1) the increased expression and activation of TFs cJun and c-Fos; 2) a higher binding capability of these at position -666 of the NOS-3 promoter; 3) a decrease of the transcriptional activity of the promoter and the expression and activity of NOS-3; and 4) the expression increase of cyclin D1. Specific inhibition of AP-1 by the retinoid SR 11302 counteracted the cytotoxic effects induced by GCDCA while promoting NOS-3 expression recovery and cyclin D1 reduction. NOS activity inhibition by L-NAME inhibited the protective effect of SR 11302. Inducible NOS isoform was no detected in this experimental model of cholestasis. Our data provide direct evidence for the involvement of AP-1 in the NOS-3 expression regulation during cholestasis and define a critical role for NOS-3 in regulating the expression of cyclin D1 during the cell damage induced by bile acids. AP-1 appears as a potential therapeutic target in cholestatic liver diseases given its role as a transcriptional repressor of NOS-3.

MeSH terms

  • Apoptosis / drug effects*
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology
  • Cyclin D1 / antagonists & inhibitors
  • Cyclin D1 / metabolism
  • Down-Regulation / drug effects*
  • Genes, Reporter
  • Glycochenodeoxycholic Acid / toxicity*
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Nitric Oxide Synthase Type III / antagonists & inhibitors
  • Nitric Oxide Synthase Type III / metabolism*
  • Oxidative Stress / drug effects
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-fos / metabolism
  • Proto-Oncogene Proteins c-jun / metabolism
  • Retinoids / chemistry
  • Retinoids / metabolism
  • Retinoids / pharmacology*
  • Transcription Factor AP-1 / antagonists & inhibitors
  • Transcription Factor AP-1 / metabolism*
  • Up-Regulation / drug effects

Substances

  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogene Proteins c-jun
  • Retinoids
  • SR 11302
  • Transcription Factor AP-1
  • Cyclin D1
  • Glycochenodeoxycholic Acid
  • NOS3 protein, human
  • Nitric Oxide Synthase Type III
  • NG-Nitroarginine Methyl Ester

Grants and funding

The authors have no support or funding to report.