Epigenetic Factors That Regulates Metastasis Of Hepatocellular Carcinoma

Objective:This study mainly focuses on the role of epigenetic factor SIRT6 in liver cancer metastasis,and discusses the molecular mechanism of primary liver cancer metastasis to other organs or tissues,so as to provide theoretical and experimental support for the development of new liver cancer targeting drugs for SIRT6 in the next stage of research.Methods:1.In vitro cytological experiments: SIRT6 overexpressed plasmid(Flag-SIRT6)and SIRT6 sh RNA fragment(sh SIRT6#1 and sh SIRT6#2,control sh Scram)were transfected into Hep G2 and SK-HEP1 cells,respectively.The transfection efficiency of SIRT6 was detected by WB.Cell slide scratch assay and Transwell cell migration assay were used to detect the migration and infiltration of HCC cells.The expression and localization of MMPs\SIRT6 in HCC cells after intervention were observed by chip-chromatin immunoprecipitation,QRT-PCR and immunofluorescence.2.In vivo zoological experiment: SIRT6 overexpression plasmid(Flag-SIRT6)and SIRT6 sh RNA fragment(sh SIRT6#1 and sh SIRT6#2,control sh Scram)were transfected into SK-HEP1 cells,and SK-HEP1 cells were injected into BALB/ C at the rate of 1×106 cells/mouse.In the caudal vein of SPF mice aged 3-4 weeks.The model of lung metastasis of hepatocellular carcinoma in mice was established.Mice were killed 4weeks after injection.The lung tissue was stained with hematoxylin and eosin and pulmonary nodules were counted.3.Statistical software SPSS17.0 and Graph Pad Prism5.0 were used for data analysis.All data were expressed as mean ± standard deviation.Homogeneity of variance test was performed for each group of data,independent sample T test was used for comparison between two groups of data,one-way analysis of variance(ANOVA)was used for comparison between multiple groups of data,and P < 0.05 was considered statistically significant.Results:1.SIRT6 knockdown significantly inhibited sk-HEP1 lung metastasis in animal models,and decreased the migration ability of SK-HEP1 and Hep G2 cells in vitro;2.SIRT6 knockdown results in morphological changes and epithelial-mesenchymal transition(EMT)phenotype transformation of HCC;3.SIRT6 overexpression but not enzyme inactivation(SIRT6H187Y)promotes EMT and migration in hepatocellular carcinoma epithelium;4.SIRT6 induces increased transcription of MMP7 and enhances the binding of transcription factors including C-Jun and TCF to the MMP7 promoter.MMP7 knockdown and JNK inhibitors completely eliminated SIRT6-mediated HCC cell migration.Conclusion:Our study reveals a novel mechanism for HCC metastasis: the interaction between SIRT6 and MMP7 controls EMT and HCC metastasis in HCC cells,and therapies targeting SIRT6 and/or MMP7 may provide novel strategies for HCC treatment.