Epigenetic silencing of miR-126 contributes to tumor invasion and angiogenesis in colorectal cancer

Oncol Rep. 2013 Oct;30(4):1976-84. doi: 10.3892/or.2013.2633. Epub 2013 Jul 23.

Abstract

microRNAs (miRNAs) have been reported to play a crucial role in regulating a variety of genes pivotal for tumor metastasis. miR-126 is well known as one of the angiogenesis regulatory miRNAs. Recent studies have reported controversial roles of miR-126 in tumor progression. In this study, we sought to investigate the potential roles of miR-126 in colorectal cancer (CRC). By real-time PCR, miR-126 was shown to be downregulated in primary CRC tissues and cell lines. Restoration of miR-126 in CRC cells inhibited cell growth, migration and invasion. Using both in silico prediction and immunoblotting, we found that vascular endothelial growth factor (VEGF) was a target of miR-126. The interaction of miR-126 on the 3'UTR of VEGF mRNA was validated by luciferase reporter assay. Mechanistically, we found that the silencing of miR-126 was induced by promoter methyl-ation of its host gene, EGFL7. Treatment with 5-aza-CdR restored miR-126 expression and thereby led to a decline in VEGF expression. Functionally, due to suppression of VEGF, enhanced miR-126 expression inhibited tumor neovasculature triggered by CRC cells. In conclusion, our findings suggest that DNA methylation-induced silencing of miR-126 contributes, at least in part, to tumor invasion and angiogenesis in CRC, through upregulation of VEGF expression. miR-126 may be a potential target for the therapeutic strategy against CRC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions / genetics
  • Azacitidine / analogs & derivatives
  • Azacitidine / pharmacology
  • Calcium-Binding Proteins
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Cell Proliferation
  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms / pathology*
  • Cytidine Triphosphate / analogs & derivatives
  • Cytidine Triphosphate / pharmacology
  • DNA Methylation / genetics
  • EGF Family of Proteins
  • Endothelial Growth Factors / genetics
  • Epigenesis, Genetic / genetics
  • Gene Expression Regulation, Neoplastic
  • HCT116 Cells
  • HEK293 Cells
  • HT29 Cells
  • Humans
  • MicroRNAs / biosynthesis
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Neoplasm Invasiveness / genetics*
  • Neoplasm Invasiveness / pathology
  • Neovascularization, Pathologic / genetics*
  • Promoter Regions, Genetic
  • RNA, Messenger / metabolism
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism*

Substances

  • 3' Untranslated Regions
  • Calcium-Binding Proteins
  • EGF Family of Proteins
  • EGFL7 protein, human
  • Endothelial Growth Factors
  • MIRN126 microRNA, human
  • MicroRNAs
  • RNA, Messenger
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • Cytidine Triphosphate
  • 5-aza-2'-deoxycytidine-5'-triphosphate
  • Azacitidine