PRMT1 Promotes EMT Via TGF-?/Smad Pathway In Hepatocellular Carcinoma Cells

Objective: Protein arginine methyltransferase 1(PRMT1)is dysregulated in a number of human cancers.However,the role of PRMT1 in hepatocellular carcinoma progression is still unclear.The aim of the present study is to investigate the effects of protein arginine methyltransferase 1(PRMT1)on cell proliferation,migration,invasion and EMT in hepatocellular carcinoma cells and further detect the molecular mechanism.This study might provide a new therapeutic target for the clinical treatment of hepatocellular carcinoma.Methods: Firstly,we analysed the m RNA and protein expression of PRMT1 in normal liver tissues and hepatocellular carcinoma tissues in few databases.Then,we analysed the association between PRMT1 expression and liver tumor clinical outcomes.We first examined the expression level of PRMT1 in Hep G2,Bel-7402 and SMMC-7721 cells using real-time PCR and Western blot.The plasmid sh-PRMT1 was used to package lentivirus to infect cells that express higher level of PRMT1.Stable cells were selected by puromycin.The plasmid Flag-PRMT1 was constructed and tranfected into cells that express lower level of PRMT1.Stable cells were selected by G418.The efficiency of these plasmids was tested by Western blot and Real-time PCR.CCK-8 assay,plate colony assay,migration assay and invasion assay were taken to detect the abilities of cell proliferation,migration and invasion in hepatocellular carcinoma cells.Invasion-related protein,MMP2 and MMP9,were detected by Western blot.EMT markers E-cadherin,N-cadherin,Vimentin and Snail were detected by Western blot.Moreover,the related protein level of TGF-?/Smad pathway was detected by Western blot.Results: Firstly,we find that PRMT1 expression is higher in hepatocellular carcinoma tissues than that in normal liver tissues at both m RNA and protein levels,and higher expression of PRMT1 correlates with poor survival in liver tumors.PRMT1 m RNA and protein levels were highest in Bel-7402 cell than that of SMMC-7721 and Hep G2 cells,the least is Hep G2 cells.The plasmid sh-PRMT1 was transfected into Bel-7402 and SMMC-7721 cells.The expression of PRMT1 was efficiently down-regulated at both protein and m RNA levels(P<0.05).The plasmid Flag-PRMT1 was successfully constructed and transfected into Hep G2 and SMMC-7721 cells.The expression of PRMT1 was strongly up-regulated at both protein and m RNA levels(P<0.05).The data in vitro reveals that PRMT1 knockdown inhibits the abilities of proliferation,migration and invasion and reduces the protein levels of MMP2 and MMP9 in hepatocellular carcinoma cells.Further studies indicate that PRMT1 knockdown remarkably decreases the expression of mesenchymal markers including Vimentin,Snail and N-cadherin,and up-regulates expression of epithelial markers E-cadherin(P<0.05).Additionally,we identify that PRMT1 knockdown results in down-regulation of TGF-?,p-Smad2 and p-Smad3(P<0.05).Conversely,PRMT1 overexpression results in the opposite effects.Conclusion: PRMT1 is overexpressed in hepatocellular carcinoma tissues and associated with patient outcome of hepatocellular carcinoma.Our work suggested that PRMT1 promoted the ability of proliferation and migration in hepatocellular carcinoma cells.Accordingly,it is suggested that PRMT1 promotes EMT in hepatocellular carcinoma cells probably via TGF-?/Smad pathway,and might represent a novel anti-liver cancer strategy.