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

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 express...

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Bibliographic Details
Published in:Molecular and cellular biochemistry 2011-05, Vol.351 (1-2), p.157-164
Main Authors: Zhu, Ni, Zhang, Dongze, Xie, Haoping, Zhou, Zhe, Chen, Huyan, Hu, Tiantian, Bai, Yuan, Shen, Yuan, Yuan, Wenjun, Jing, Qing, Qin, Yongwen
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Biochemistry
Biomedical and Life Sciences
Breast cancer
Breast Neoplasms - enzymology
Breast Neoplasms - genetics
Breast Neoplasms - metabolism
Cardiology
Cells, Cultured
DNA Primers
Down-Regulation
Endothelium
Endothelium, Vascular - metabolism
Female
Gene expression
Humans
Introns
Life Sciences
Luciferase
Male
Medical Biochemistry
MicroRNA
MicroRNAs - genetics
Oncology
Phosphatidylinositol 3-Kinases - metabolism
Polymerase Chain Reaction
Proteins
Rats
Rats, Sprague-Dawley
Real time
Signal Transduction
Vascular endothelial growth factor
Vascular Endothelial Growth Factor A - metabolism
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Summary: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.
ISSN:0300-8177
1573-4919
DOI:10.1007/s11010-011-0723-7