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  • Pharmacological application of caffeine inhibits TGF-beta-stimulated connective tissue growth factor expression in hepatocytes via PPARgamma and SMAD2/3-dependent pathways.

Pharmacological application of caffeine inhibits TGF-beta-stimulated connective tissue growth factor expression in hepatocytes via PPARgamma and SMAD2/3-dependent pathways.

Journal of hepatology (2008-05-20)
Olav A Gressner, Birgit Lahme, Katharina Rehbein, Monika Siluschek, Ralf Weiskirchen, Axel M Gressner
ABSTRACT

Epidemiological studies suggest that coffee drinking is inversely correlated with the risk of development of liver fibrosis but the molecular basis is unknown. We investigated the pharmacological mechanisms involved in caffeine-dependent regulation of CTGF expression, an important modulator protein of fibrogenic TGF-beta, in rat hepatocytes using Western-blot, co-immunoprecipitations, reporter-gene-assays and ELISAs. It is demonstrated that caffeine, similar to 8-Br-cAMP, suppresses CTGF expression, decreases SMAD2 protein levels and inhibits SMAD1/3-phosphorylation. The SMAD2 level can be restored by a proteasome inhibitor. Additionally, caffeine leads to an up-regulation of PPARgamma expression, that enhances the inhibitory effect of the natural PPARgamma agonist 15-PGJ(2) on CTGF expression by inducing a dissociation of the SMAD2/3-CBP/p300-transcriptional complex. We show that caffeine strongly down-modulates TGF-beta-induced CTGF expression in hepatocytes by stimulation of degradation of the TGF-beta effector SMAD 2, inhibition of SMAD3 phosphorylation and up-regulation of the PPARgamma-receptor. Long-term caffeinization might be an option for anti-fibrotic trials in chronic liver diseases.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-p300/CBP antibody, Mouse monoclonal antibody produced in mouse, clone NM11, purified from hybridoma cell culture
Sigma-Aldrich
Caffeine, anhydrous, tested according to Ph. Eur.