title: microRNA-146a inhibits cancer metastasis by downregulating VEGF through dual pathways in hepatocellular carcinoma.
abstract: Growing evidence indicates that miR-146a is involved in carcinogenesis and tumor progression in several human malignancies. However, the molecular details underlying miR-146a mediated regulation of its target genes and its precise biological function in cancer, especially in hepatocellular carcinoma (HCC) remains unclear.
  
  
  METHODS
  The expression levels of genes including miR-146a, APC, VEGF and HAb18G were examined in HCC cell lines and patient specimens were compared with control levels using quantitative reverse transcription-PCR. The functions of miR-146a and HAb18G in migration/invasion and liver metastasis formation were determined by transwell and spleen injection assays, respectively. miR-146a related genes were determined by PCR array. The potential regulatory targets of miR-146a were determined by bioinformatics and prediction tools, correlation with target protein expression, and luciferase reporter assay. DNA methylation status of miR-146a promoter were performed by PCR analysis of bisulfite-modified genomic DNA.
  
  
  RESULTS
  We demonstrated that miR-146a expression was markedly downregulated in hepatoma cells and hepatoma tissues compared to immortalized normal liver epithelial cells and normal hepatic tissues. DNA methylation of miR-146a promoter correlated with its downexpression and with liver cancer metastasis. The restoration of miR-146a dramatically suppressed HCC cell invasion and metastasis by repressing VEGF expression through upregulating APC, which inhibits β-catenin accumulation in nucleus, and downregulating NF-κB p65 by targeting HAb18G. In human HCC, miR-146a expression was negative correlated with increased HAb18G, VEGF, NF-κB p65 and beneficial prognosis.
  
  
  CONCLUSIONS
  This study identified a novel target of miR-146a and defined miR-146a as a crucial tumor suppressor in human HCC that acts through multiple pathways and mechanisms to suppress HCC invasion or metastasis.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiu-Xuan
authors.initials: XX
authors.lastname: Sun
authors.forename: Xi
authors.initials: X
authors.lastname: Ma
authors.affiliation: Cell Engineering Research Center & Department of Cell Biology, State Key Laboratory of Cancer Biology, Fourth Military Medical University, Xi'an 710032, P, R, China. znchen@fmmu.edu.cn.
authors.forename: Zhi-Nan
authors.initials: ZN
authors.lastname: Chen
mesh_terms: D020413:3' Untranslated Regions; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051926:Basigin / Q000235:genetics; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D045744:Cell Line, Tumor; D019175:DNA Methylation; D004195:Disease Models, Animal; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D064593:Heterografts; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics*; D009362:Neoplasm Metastasis; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D015398:Signal Transduction; D042442:Vascular Endothelial Growth Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D025601:Adenomatous Polyposis Coli Protein; C497886:BSG protein, human; C542542:MIRN146 microRNA, human; D035683:MicroRNAs; D042442:Vascular Endothelial Growth Factors; D051926:Basigin