The Molecular Mechanism Of Histone Deacetylase Inhibitors Inducing Epithelia-mesenchymal Transitions In Hepatocellular Carcinoma

Objective:To explore the specific mechanism of HDACi which have limited effects in the treatment of hepatocellular carcinoma,and to provide theoretical basis for the combination of HDACi and other drugs in the treatment of hepatocellular carcinoma.Methods: Experiments were divided into three parts.Part I: The hepatoma cell lines HepG2 and QGY-7703 were cultured in vitro to construct the EMT models.The expressions of EMT markers Fn,Vim and N-cad were analyzed by WB and RT-PCR.Part II: Mechanism of HDACi(SAHA,NaB)promote hepatocellular carcinoma EMT by maintaining the stability of Snai1 protein by IP and so on.Part III: Molecular mechanism of HDACi(SAHA,NaB)promote hepatocellular carcinom EMT by activating Snail transcription through Smads signaling pathway by IF?EMSA?the dual luciferase reporter gene assay and so on.Results:1.HDACi(SAHA,NaB)can induce hepatocellular carcinoma cell lines HepG2 and QGY-7703 morphological changes and EMT to promote cells invasion and metastasis,and enhance the movement ability of cells.2.Snail regulates HDACi(SAHA,NaB)-induced hepatocellular carcinoma EMT.3.HDACi(SAHA,NaB)can significantly delay the degradation of Snail protein and mRNA and promote the occurrence of EMT in hepatocellular carcinoma cell lines HepG2 and QGY-7703.4.HDACi(SAHA,NaB)activates the Smads pathway to enhance the phosphorylation and nuclear translocation of Smad2 and Smad3 in HepG2 and QGY-7703 cells,which promote the binding of Smads to the Snail promoter,inducing Snail transcription and up-regulation of Snail protein to promote hepatocellular carcinoma EMT.Conclusion : In this study,we demonstrated that HDACi(SAHA,NaB)can promote EMT in hepatocellular carcinoma cell lines HepG2 and QGY-7703,and enhance cells invasion and migration.Further mechanism research demonstrated that HDACi(SAHA,NaB)induced the expression of CSN2,then binded to Snail,promoting acetylation of Snail,blocked its phosphorylation and ubiquitination sites,which delay the degradation of Snail proteins and mRNA.Furthermore,HDACi(SAHA,NaB)can upregulate the expression of Snail protein by activating of Smadssignaling pathway to promote smads combined with Snail promoter.All the upregulated Snail protein can induce EMT in hepatocellular carcinoma.Therefore,this study provided the foundation for the application of HDACi,which suggests that HDACi combines with other drugs to inhibit EMT maybe the best way to take full advantage of HDACi in the treatment of hepatocellular carcinoma.