Endothelial-specific intron-derived miR-126 is down-regulated in human breast cancer and targets both VEGFA and PIK3R2

Mol Cell Biochem. 2011 May;351(1-2):157-64. doi: 10.1007/s11010-011-0723-7. Epub 2011 Jan 20.


Endothelial cells are the key components of vascular intima and play pivotal roles in vasculogenesis, angiogenesis, and tumor growth. Using Northern blot and real-time PCR, we confirmed that miR-126 and its host gene EGF-like domain 7 (EGFL7) were widely expressed in rat tissues but strictly expressed in endothelial cells. In mammals, miR-126 gene is embedded in intron7 of EGFL7. To explore the biogenesis of miR-126, plasmid EGFL7(126)-pEGFPc1 containing segment of exon7-intron7-exon8 of EGFL7 was constructed and expressed in 293T. Expression of spliced exon7-8 and excised mature miR-126 was detected by PCR and Northern blot. Knocking-down of endothelial endogenous miR-126 did not affect EGFL7 expression at mRNA or protein level. To investigate the possible roles of miR-126, PicTar, miRBase, miRanda, Bibiserv, and Targetscan were used to screen the targets. VEGFA and PIK3R2 were confirmed as the targets of miR-126 by luciferase reporter assay and Western blot. Interestingly, Northern blot and western blot showed that miR-126 was down-regulated in breast tumors where the VEGF/PI3K/AKT signaling pathway was activated. Introduction of miR-126 mimics into MCF-7 could effectively decrease VEGF/PI3K/AKT signaling activity. In summary, miR-126 was strictly expressed in endothelial cells and excised from EGFL7 pre-mRNA without affecting splicing and expression of its host gene. In addition, miR-126 could target both VEGFA and PIK3R2, and its expression was decreased in human breast cancer, implying that miR-126 may play a role in tumor genesis and growth by regulating the VEGF/PI3K/AKT signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Breast Neoplasms / enzymology
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / metabolism
  • Cells, Cultured
  • DNA Primers
  • Down-Regulation
  • Endothelium, Vascular / metabolism*
  • Female
  • Humans
  • Introns*
  • Male
  • MicroRNAs / genetics*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Polymerase Chain Reaction
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Vascular Endothelial Growth Factor A / metabolism*


  • DNA Primers
  • MIRN126 microRNA, human
  • MicroRNAs
  • Vascular Endothelial Growth Factor A
  • Phosphatidylinositol 3-Kinases
  • phosphoinositol-3 kinase regulatory subunit 2, human