MiR-7-5p is frequently downregulated in glioblastoma microvasculature and inhibits vascular endothelial cell proliferation by targeting RAF1
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The aberrant expression of microRNAs (miRNAs) is always associated with tumor development and progression. Microvascular proliferation is one of the unique pathologic features of glioblastoma (GBM) . In this study, the microvasculature from GBM or normal brain tissue derived from neurosurgeries was purified and total RNA was isolated from purified microvasculature. The difference of miRNA expression profiles between glioblastoma microvasculature and normal brain capillaries was investigated. It was found that miR-7-5p in GBM microvessels was significantly reduced compared with that in normal brain capillaries. In the in vitro experiments, overexpression of miR-7-5p significantly inhibited human umbilical vein endothelial cell proliferation. Forced expression of miR-7-5p in human umbilical vein endothelial cells in vitro significantly reduced the protein level of RAF1 and repressed the activity of the luciferase, a reporter vector carrying the 3′-untranslated region of RAF1. These findings indicate that RAF1 is one of the miR-7-5p target genes. Furthermore, a significant inverse correlation between miR-7-5p expression and RAF1 protein level in GBM microvasculature was found. These data suggest that miR-7-5p functions as a tumor suppressor gene to regulate GBM microvascular endothelial cell proliferation potentially by targeting the RAF1 oncogene, implicating an important role for miR-7-5p in the pathogenesis of GBM. It may serve as a guide for the antitumor angiogenesis drug development.
KeywordsMicrovasculature MiR-7-5p Glioblastoma RAF1 Proliferation
Real-time quantitative reverse transcriptase PCR
We thank Yan Song, Meng Zhang, and Yubao Zhang for the administrative and operational support; Drs. Guiyan Xu, Guangming Qu, Deze Jia, and Donghai Wang for their helpful discussions and critical reading of the manuscript.
Ethics approval was provided by the National Hospital for Neurology and Neurosurgery Research Ethics Committee.
Conflicts of interest
None, there are no conflict of interest.
This work was supported by the National Natural Scientific Foundation of China (NO.81141088) and by the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province. (NO. 2004BS02010). JYL was supported by North Shore-LIJ Cancer Institute.
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