Notch Inhibition via Micro-RNA Blocks Glioma Development

ArticleinNeurosurgery 70(4):N20-2 · April 2012with1 Reads
DOI: 10.1227/01.neu.0000413225.95714.c9 · Source: PubMed
  • [Show abstract] [Hide abstract] ABSTRACT: Histone deacetylases (HDACs) constitute a family of enzymes that play important roles in the epigenetic regulation of gene expression and contribute to the growth, differentiation and apoptosis of cancer cells. However, the biological function of HDAC5 in glioma cells has not been fully understood. In the present study, we found that the mRNA and protein levels of HDAC5 are increased in human glioma tissues and cell lines. In addition, overexpression of HDAC5 promoted proliferation of glioma cells, as measured by the MTT assay. By contrast, HDAC5 gene silencing using small interfering RNA (siRNA) inhibited cell proliferation. Furthermore, we demonstrated that HDAC5 enhances Notch 1 expression at both the mRNA and the protein level in glioma cell lines. Taken together, these results demonstrated, for the first time to the best of our knowledge, that HDAC5 promotes glioma cell proliferation, and suggest that this effect involves the upregulation of Notch 1. Therefore, our study may provide a novel therapeutic target for treatment of gliomas.
    Article · Jul 2014
  • [Show abstract] [Hide abstract] ABSTRACT: Notch signaling has been reported to be oncogenic or tumor suppressive, depending on the tissue context. To investigate the effects of Notch2 knockdown on U87 human glioma cell proliferation in vitro and in vivo, and the associated mechanisms, U87 cells were stably transfected with p green fluorescent protein (GFP)‑V‑RS Notch2 short hairpin (sh) RNA plasmid and pGFP‑V‑RS scramble‑shRNA plasmid. The former was referred to as the Notch2‑shRNA group and the latter as the negative‑shRNA group. mRNA and protein expression, cell proliferation, cell cycle and apoptosis were measured by reverse transcription‑polymerase chain reaction, western blot analysis, 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide analysis and flow cytometry using propidium iodide, respectively. Tumor volume, tumor weight and cumulative survival rate were determined in a nude mouse xenograft tumor model. Notch2 mRNA and protein expression in the Notch2‑shRNA group were reduced by 87.6 and 94.5% compared with the negative‑shRNA group (P<0.001). Notch2 knockdown significantly inhibited U87 cell proliferation after three days of culture (P<0.05). Notch2 silencing induced cell cycle arrest at G0/G1 phase by upregulation of p21 protein expression and downregulation of mini chromosome maintenance complex 2 and cyclin‑D1 protein expression. Furthermore, knockdown of Notch2 also induced U87 cell apoptosis. On day 50 after inoculation, tumor weight in the Notch2‑shRNA group was significantly lower than that in the negative‑shRNA group (0.55±0.10 vs. 1.23±0.52 g; P<0.01). The cumulative survival rate was significantly longer in the Notch2‑shRNA group compared with the negative‑shRNA group (log rank test P=0.01). In conclusion, Notch2 silencing inhibited U87 glioma cell proliferation by inducing cell cycle arrest and apoptosis in vitro and in vivo. Thus, Notch2 may be a key therapeutic target for the treatment of glioma.
    Full-text · Article · Oct 2014