Decreased Expression Of ACSS2 Promotes Metastasis And Predicts Poor Prognosis In Hepatocellular Carcinoma

Objectives:Metastasis is a serious problem of in the diagnosis and treatment of hepatocellular carcinoma(HCC),which makes many patients lose the chance of surgery and results in poor prognosis.Hypoxia inducible factors have been proved an important inducement for the occurrence of metastasis through EMT pathway.ACSS2,with the full name of acetyl-CoA synthase 2,may provide acetyl group to the acetylation of HIF-2? and plays a role on its epigenetic modifications and EMT.Our work aimed to investigate the relationship between the expression of ACSS2 and the metastasis,prognosis of HCC and explore the mechanism of ACSS2 on HIF-2? acetylation modulation.Methods:The ACSS2 expression of HCC cells and tissue specimens were detected by Western blot(WB),Real-time PCR(RT-PCR)and Immunohistochemistry(IHC).Si RNA interference technology was used to make ACSS2 down-regulated,transwell invasive assay and scratch test were performed to study the invasion and migration capacity of HCC cells.WB and RT-PCR were also used to detect expression of E-cadherin,N-cadherin,HIF-2? and its downstream molecules.Then immunoprecipitation assay was performed to detect the acetylation levels.All the results and data were analysed by SPSS 18.0(Chicago,USA)software and expressed as the means±SD.T tests were used to evaluate the differences between two groups.Survival curves(OS,DFS)of patients were calculated by Kaplan–Meier analysis.The chi-square test was used to explore the relationship between two variables.Results:1.Western blot(WB)results revealed that the MHCC97 L and Hep3 B cells exhibited higher ACSS2 expression than the more malignant MHCC97 H and LM3 cell lines.WB and RT-PCR data of HCC samples showed that the non-carcinoma tissues exhibited higher ACSS2 expression than carcinoma.2.Scratch test and transwell invasive assay demonstrated that ACSS2 knockdown promoted the invasion and migration ability of HCC cells in hypoxia condition.3.The morphology of MHCC97 H after siRNA interference in normoxia and hypoxia condition revealed the phenomenon of EMT.Moreover,WB assay of relevant indicators of EMT displayed that ACSS2 konckdown promoted epithelial-mesenchymal transition(EMT)of HCC cells without HIF-2? elevation in hypoxia condition.4.Immunoprecipitation assay revealed that there was a down-regulation in acetylation levels of HIF-2? after ACSS2 konckdown in hypoxia condition.This deacetylation process enhances the function of HIF-2?.5.IHC assay indicated that low expression of ACSS2 associates with poor prognosis and clinical stage.Loss of ACSS2 may be related to more metastasis risk.A small sample of WB showed that loss of ACSS2 may occur gradually in the process of HCC development.Conclusions: ACSS2 plays an important role in the acetylation of HIF-2?.Loss of ACSS2 promotes HIF-2? deacetylation and enhances part function of HIF-2? under hypoxia condition,which results in metastasis and poor prognosis of HCC.