Epigallocatechin gallate and genistein attenuate glial fibrillary acidic protein elevation induced by fibrogenic cytokines in hepatic stellate cells

Abstract

Hepatic stellate cells (HSCs) play a pivotal role in hepatic fibrogenesis, and are considered a cellular target for therapeutic intervention. We recently established that a 2.2-kb hGFAP (human glial fibrillary acidic protein) promoter could be used to specifically target cultured HSCs. In the current study, we aimed to investigate whether the same transgene (2.2-kb hGFAP-lacZ) can be used as a biomarker for studying the inhibition of HSC activation. HSC-T6 cells stably transfected with the transgene were treated with two natural anti-fibrotic compounds, epigallocatechin gallate (EGCG) and genistein separately. Results showed that both transgenic ß-galactosidase activity and endogenous GFAP expression (mRNA and protein) were attenuated by EGCG or genistein treatment in a dose- and time-dependent manner. Our data further demonstrated that the suppression of fibrogenic endpoints was primarily mediated through the inhibition of AP-1 signaling (and to a lesser degree through the NFκB pathway) onto the GFAP promoter. In conclusion, the current findings provide a proof-of-concept for using GFAP for studying HSC activation and inhibition. It could be envisioned that a HSC-based high-throughput system can be constructed using the GFAP promoter in conjunction with a real-time reporter for the screening of anti-fibrotic and anti-inflammatory agents.