Stabilization of IGFBP-1 mRNA by ethanol in hepatoma cells involves the JNK pathway.
OBJECTIVE
Insulin-like growth factor-binding protein-1 (IGFBP-1) modulates cell growth and metabolism in a variety of physiopathological conditions. The aim of this study was to determine the molecular mechanisms involved in IGFBP-1 upregulation by ethanol.


METHODS
We studied IGFBP-1 regulation by ethanol at the protein, mRNA and gene promoter levels in the human hepatocarcinoma cell line, HepG2, which does not express significantly ethanol-metabolizing enzymes.


RESULTS
Ethanol (35-150mM) induced the IGFBP-1 mRNA and protein up to 5-fold in a dose-dependent manner. A similar effect was observed using primary cultures of human hepatocytes. Various inhibitors of ethanol metabolism and the antioxidant N-acetylcysteine did not prevent ethanol effects. While ethanol did not modify the IGFBP-1 gene promoter activity, it elicited a 2- to 3-fold increase in IGFBP-1 mRNA half-life and this stabilization required the 5' and the 3' untranslated mRNA region. Ethanol triggered a rapid activation of c-Jun N-terminal Kinase (JNK) in HepG2 cells and IGFBP-1 induction was significantly decreased by a specific inhibitor of JNK.


CONCLUSIONS
This study reveals a novel pathway of gene regulation by alcohol which involves the activation of JNK and the consequent mRNA stabilization.
Magne
Laurent
L
INSERM U747, Laboratoire de Pharmacologie, Toxicologie et Signalisation Cellulaire, Paris F-75006, France.
Blanc
Etienne
E
Marchand
Alexandre
A
Fafournoux
Pierre
P
Barouki
Robert
R
Rouach
Hélène
H
Garlatti
Michèle
M
D000975:Antioxidants / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D045744:Cell Line, Tumor; D002492:Central Nervous System Depressants / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D000431:Ethanol / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000235:genetics* / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D020871:RNA Stability / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D000975:Antioxidants; D002492:Central Nervous System Depressants; C032231:IGFBP1 protein, human; D018970:Insulin-Like Growth Factor Binding Protein 1; D012333:RNA, Messenger; D000431:Ethanol; D048031:JNK Mitogen-Activated Protein Kinases