Dataset Information

MiR-124 governs glioma growth and angiogenesis and enhances chemosensitivity by targeting R-Ras and N-Ras.

ABSTRACT:

Background

Glioma is one of the most aggressive and lethal human brain tumors. Accumulating evidence shows that microRNAs play important roles in cancers, including glioma. Previous studies reported that miR-124 levels were downregulated in glioma specimens. Here, we further investigate the potential role of miR-124 in glioma.

Methods

The expression levels of miR-124 were detected in glioma specimens by quantitative reverse transcriptase PCR. The direct targets of miR-124 were identified by bioinformatics analysis and were further validated by immunoblotting and luciferase reporter assay. The effects of miR-124 on glioma cell proliferation and chemosensitivity to temozolomide were analyzed by Cell-Counting Kit 8 assay. Apoptosis was evaluated by fluorescence activated cell sorting analysis. A xenograft model was used to study the effect of miR-124 on tumor growth and angiogenesis.

Results

Expression levels of miR-124 were greatly downregulated in glioma specimens. related Ras viral oncogene homolog (R-Ras) and neuroblastoma Ras viral oncogene homolog (N-Ras) were identified as direct targets of miR-124. MiR-124 inhibited glioma cell growth, invasion, angiogenesis, and tumor growth and increased chemosensitivity to temozolomide treatment by negatively regulating the Ras family and its downstream signaling pathways: phosphatidylinositol-3 kinase/Akt and Raf/extracellular signal-regulated kinase 1/2. Furthermore, overexpression of R-Ras rescued the inhibitory effects of miR-124. Meanwhile, overexpression of R-Ras and N-Ras restored miR-124-inhibited vascular endothelial growth factor (VEGF) transcription activation. In clinical glioma specimens, protein levels of R-Ras and N-Ras were upregulated and inversely correlated with miR-124 expression levels.

Conclusions

Taken together, these results revealed that miR-124 levels in tumor tissues are associated with glioma occurrence, angiogenesis, and chemoresistance and that miR-124 may be used as a new diagnostic marker and therapeutic target for glioma in the future.

SUBMITTER: Shi Z

PROVIDER: S-EPMC4165420 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Publications

MiR-124 governs glioma growth and angiogenesis and enhances chemosensitivity by targeting R-Ras and N-Ras.

Shi Zhumei Z Chen Qiudan Q Li Chongyong C Wang Lin L Qian Xu X Jiang Chengfei C Liu Xue X Wang Xiefeng X Li Hai H Kang Chunsheng C Jiang Tao T Liu Ling-Zhi LZ You Yongping Y Liu Ning N Jiang Bing-Hua BH

Neuro-oncology 20140525 10

<h4>Background</h4>Glioma is one of the most aggressive and lethal human brain tumors. Accumulating evidence shows that microRNAs play important roles in cancers, including glioma. Previous studies reported that miR-124 levels were downregulated in glioma specimens. Here, we further investigate the potential role of miR-124 in glioma.<h4>Methods</h4>The expression levels of miR-124 were detected in glioma specimens by quantitative reverse transcriptase PCR. The direct targets of miR-124 were ide ...[more]

PMID: 24861879

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Project description:BACKGROUND:Chemoresistance to temozolomide (TMZ) is a major challenge in the treatment of glioblastoma (GBM). We previously found that miR-519a functions as a tumor suppressor in glioma by targeting the signal transducer and activator of transcription 3 (STAT3)-mediated autophagy oncogenic pathway. Here, we investigated the effects of miR-519a on TMZ chemosensitivity and autophagy in GBM cells. Furthermore, the underlying molecular mechanisms and signaling pathways were explored. METHODS:In the present study, two stable TMZ-resistant GBM cell lines were successfully generated by exposure of parental cells to a gradually increasing TMZ concentration. After transfecting U87-MG/TMZ and U87-MG cells with miR-519a mimic or inhibitor, a series of biochemical assays such as MTT, apoptosis, and colony formation were performed to determine the chemosensitive response to TMZ. The autophagy levels in GBM cells were detected by transmission electron microscopy, LC3B protein immunofluorescence, and Western blotting analysis. Stable knockdown and overexpression of miR-519a in GBM cells were established using lentivirus. A xenograft nude mouse model and in situ brain model were used to examine the in vivo effects of miR-519a. Tumor tissue samples were collected from 48 patients with GBM and were used to assess the relationship between miR-519a and STAT3 expression. RESULTS:TMZ treatment significantly upregulated miR-519a in U87-MG cells but not in U87-MG/TMZ cells. Moreover, the expression of miR-519a and baseline autophagy levels was lower in U87-MG/TMZ cells as compared to U87-MG cells. miR-519a dramatically enhanced TMZ-induced autophagy and apoptotic cell death in U87-MG/TMZ cells, while inhibition of miR-519a promoted TMZ resistance and reduced TMZ-induced autophagy in U87-MG cells. Furthermore, miR-519a induced autophagy through modification of STAT3 expression. The in vivo results showed that miR-519a can enhance apoptosis and sensitized GBM to TMZ treatment by promoting autophagy and targeting the STAT3/Bcl-2/Beclin-1 pathway. In human GBM tissues, we found an inverse correlation between miR-519a and STAT3 expression. CONCLUSIONS:Our results suggested that miR-519a increased the sensitivity of GBM cells to TMZ therapy. The positive effects of miR-519a may be mediated through autophagy. In addition, miR-519a overexpression can induce autophagy by inhibiting STAT3/Bcl-2 pathway. Therefore, a combination of miR-519a and TMZ may represent an effective therapeutic strategy in GBM.

Dataset Information

MiR-124 governs glioma growth and angiogenesis and enhances chemosensitivity by targeting R-Ras and N-Ras.

Background

Methods

Results

Conclusions

Publications

MiR-124 governs glioma growth and angiogenesis and enhances chemosensitivity by targeting R-Ras and N-Ras.

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