INTRODUCTION:Chronic liver disease is driven by a prolonged wound healing response leading to fibrogenesis, potentially progressing to cirrhosis. Hepatic stellate cells (HSCs) are the primary cells driving hepatic fibrosis because they are major producers of extracellular matrix. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ΚB) pathway is a key regulator of inflammatory signaling, and survival of activated HSCs has been found to be NF-KB dependent. Our team previously synthesized HJC0416-a signal transducer and activator of transcription three inhibitor with potent anti-inflammatory effects. In HSCs, HJC0416 reduced cell viability, extracellular matrix production, and-notably-NF-KB activation. However, HJC0416's antifibrogenetic mechanism remains unknown. This study examined the effects of HJC0416 on NF-KB and its associate factor HSP-90 in HSCs.
METHODS:The activated human HSC line LX-2 was treated with either HJC0416 or 17-AAG, then exposed to TNFα as indicated. Nuclear and cytosolic proteins were isolated for Western blot or immunofluorescence assay.
RESULTS:HJC0416 significantly attenuated TNFα-induced IκBα phosphorylation, NF-KBp65 nuclear translocation, and DNA binding activity. Endogenous and TNFα-induced p65 phosphorylation of S536 was suppressed by HJC0416. Notably, HJC0416 dose-dependently attenuated the expression of FAK, IKKα, and signal transducer and activator of transcription three which are Heat Shock Protein 90 (HSP90) interacting proteins. The expression of other HSP90 interacting proteins-RIP1, AKT, FAK, and cyclin-dependent kinase nine-were decreased. HSP90-specific inhibitor 17-AAG significantly attenuated TNFα-induced IκBα phosphorylation and degradation, p65 nuclear translocation, DNA binding, and production of collagen type I and fibronectin.
CONCLUSIONS:The HSP90 chaperone protein may be a key intermediary linking HJC0416's ability to inhibit NF-κB activity. HJC0416 may be a promising drug candidate for liver fibrosis.
