Natural and synthetic STAT3 inhibitors reduce hepcidin expression in differentiated mouse hepatocytes expressing the active phosphorylated STAT3 form
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During the inflammatory process, hepcidin overexpression favours the development of anaemia of chronic diseases which represents the second most common form of anaemia worldwide. The identification of therapeutic agents decreasing hepcidin expression is therefore an important goal. The aim of this study was to target the STAT3 signalling involved in the development of increased hepcidin expression related to chronic inflammation. In a co-culture model associating mouse hepatocytes and rat liver epithelial cells, the mRNA levels of hepcidin1, albumin, aldolase B, Cyp3a4, Stat3, Smad4 and iron regulatory genes were measured by real-time PCR. STAT3 and phosphorylated SMAD1/5/8 proteins were analysed by Western blot. At variance of hepatocyte pure culture, co-culture provided high levels of hepcidin1 mRNA, reaching 400% of the freshly isolated hepatocyte values after 6 days of culture. Hepcidin expression was associated with the maintenance of hepatocyte phenotype, STAT3 phosphorylation and functional BMP/SMAD pathway. Stat3 siRNAs inhibited the hepcidin1 mRNA expression. STAT3 inhibitors, including curcumin, AG490 and a peptide (PpYLKTK), reduced hepcidin1 mRNA expression even when cells were additionally exposed to IL-6. Hepcidin1 mRNA was expressed at high levels by hepatocytes in the co-culture model, and STAT3 pathway activation was controlled through STAT3 inhibitors. Such inhibitors could be useful to prevent anaemia related to hepcidin overexpression during chronic inflammation.
KeywordsHepcidin STAT3 Hepatocytes Co-culture Inflammation Iron Gene expression
This work was supported by grants from the EEC FP6 programme: LSHM-CT-2006-037296 Euroiron1, Région Bretagne (PRIR 139) and the “Association pour la Recherche contre le Cancer” (NF), Villejuif, France. We thank André Guillouzo and Christiane Guguen-Guillouzo for their critical reading of the manuscript and Catherine Ribault for her helpful technical contribution.
Disclosure of potential conflict of interests
The authors declare that they have no conflicting interests related to this study.
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