MicroRNA-520b affects the proliferation of human glioblastoma cells by directly targeting cyclin D1

Abstract

Glioblastoma (GBM) represents one of most common tumors in humans. However, the biological processes and molecular mechanisms of GBM are still unclear. It is known that microRNA-520b (miR-520b) participates in the development of various tumor progressions. The present study was to evaluate the level of miR-520b in GBM tissues and cells. We further investigated the molecular mechanisms of miR-520b in U87 and U251 cell lines. Here, our data showed that the expression levels of miR-520b were significantly reduced in clinical GBM tissues and cell lines. Accordingly, the expression levels of cyclin D1 were significantly increased in clinical GBM tissues and cell lines. Ectopic expression of miR-520b in U87 and U251 cells resulted in decreased cell proliferation and enhanced cell apoptosis. Further study characterized the 3' untranslated region (3'-UTR) of cyclin D1 gene as a direct target of miR-520b in U87 and U251 cells as determined by luciferase reporter assays. In addition, ectopic expression of miR-520b led to the down-regulation of phosphorylated retinoblastoma (p-Rb, a downstream effector of cyclin D1), while the overexpression of cyclin D1 reversed the miR-520b-induced inhibition of p-Rb expression. In conclusion, this study highlights the importance of miR-520b in regulating the proliferation and apoptosis of GBM by directly targeting cyclin D1, and miR-520b may represent a potential therapeutic strategy for GBM.

RETRACTED ARTICLE: MiR-124 Functions as a Tumor Suppressor via Targeting hCLOCK1 in Glioblastoma

“…MicroRNAs (miRNAs) are a recently discovered category of small (19~24 nucleotides), non-protein-coding and singlestranded endogenous RNA molecules [7]. miRNAs function as regulators of approximately 60 % protein-coding gene expression mainly at the posttranscriptional level by binding to the sequences in the 3′ untranslated region (3′-UTR) of their targeted messenger RNAs (mRNAs) resulting in translational repression or gene silencing [8].…”

Identification of microRNAs associated with the aggressiveness of prolactin pituitary tumors using bioinformatic analysis

“…However, the roles of hsa-miR-489 in pituitary tumors, especially aggressive prolactinomas, have not been previously studied. Additionally, hsa-miR-520b was reported to have a suppressive effect on tumor cell proliferation, migration, invasion and epithelial-to-mesenchymal transition (EMT) in colorectal cancer (49), glioblastoma (50), hepatoma (51), head-neck cancer (52), breast cancer (53), lung cancer (54) and gastric cancer (55). Expression of hsa-miR-520b is lower in tumor tissues than in normal tissues, significantly promoting the proliferation, migration, and invasion of tumor cells.…”