Yingyi Wang

Long Non-Coding RNA H19 Promotes Glioma Cell Invasion by Deriving miR-675

H19 RNA has been characterized as an oncogenic long non-coding RNA (lncRNA) in breast and colon cancer. However, the role and function of lncRNA H19 in glioma development remain unclear. In this study, we identified that H19/miR-675 signaling was critical for glioma progression. By analyzing glioma gene expression data sets, we found increased H19 in high grade gliomas. H19 depletion via siRNA inhibited invasion in glioma cells. Further, we found H19 positively correlated with its derivate miR-675 expression and reduction of H19 inhibited miR-675 expression. Bioinformatics and luciferase reporter assays showed that miR-675 modulated Cadherin 13 expression by directly targeting the binding site within the 3′ UTR. Finally, introduction of miR-675 abrogated H19 knockdown-induced cell invasion inhibition in glioma cells. To our knowledge, it is first time to demonstrate that H19 regulates glioma development by deriving miR-675 and provide important clues for understanding the key roles of lncRNA-miRNA functional network in glioma.

HOTAIR, a cell cycle-associated long noncoding RNA and a strong predictor of survival, is preferentially expressed in classical and mesenchymal glioma.

BACKGROUND Long noncoding RNA Hox transcript antisense intergenic RNA (HOTAIR) has been characterized as a negative prognostic factor in breast and colon cancer patients. The clinical significance and function of HOTAIR in glioma remains unclear. METHODS We analyzed the clinical significance of HOTAIR in 3 different glioma cohorts with gene expression data, including correlation with tumor grade, prognosis, and molecular subtype. The function of HOTAIR in glioma was explored by performing gene set enrichment analysis and in vitro and in vivo experiments. RESULTS HOTAIR expression was closely associated with glioma grade and poor prognosis. Multivariate Cox regression analysis revealed that HOTAIR was an independent prognostic factor in glioblastoma multiforme patients. HOTAIR expression correlated with glioma molecular subtype, including those of The Cancer Genome Atlas. HOTAIR was preferentially expressed in the classical and mesenchymal subtypes compared with the neural and proneural subtypes. A gene set enrichment analysis designed to show gene set differences between patients with high and low HOTAIR expression indicated that HOTAIR expression was associated with gene sets involved in cell cycle progression. HOTAIR reduction induced colony formation suppression, cell cycle G0/G1 arrest, and orthotopic tumor growth inhibition. CONCLUSION Our data establish that HOTAIR is an important long noncoding RNA that primarily serves as a prognostic factor for glioma patient survival, as well as a biomarker for identifying glioma molecular subtypes, a critical regulator of cell cycle progression.

High level of miR-221/222 confers increased cell invasion and poor prognosis in glioma

BackgroundMiR-221 and miR-222 (miR-221/222), upregulated in gliomas, can regulate glioma cell cycle progression and apoptosis, respectively. However, the association of miR-221/222 with glioma cell invasion and survival remains unknown.MethodsInvasion capability of miR-221/222 was detected by mutiple analyses, including diffusion tensor imaging (DTI), transwell, wound healing and nude mouse tumor xenograft model assay. Further, the target of miR-221/222 was determined by luciferase reporter, western blot and gene rescue assay. The association of miR-221/222 with outcome was examined in fifty glioma patients.ResultsMiR-221/222 expression was significantly increased in high-grade gliomas compared with low-grade gliomas, and positively correlated with the degree of glioma infiltration. Over-expression of miR-221/222 increased cell invasion, whereas knockdown of miR-221/222 decreased cell invasion via modulating the levels of the target, TIMP3. Introduction of a TIMP3 cDNA lacking 3’ UTR abrogated miR-221/222-induced cell invasion. In addition, knockdown of miR-221/222 increased TIMP3 expression and considerably inhibited tumor growth in a xenograft model. Finally, the increased level of miR-221/222 expression in high-grade gliomas confers poorer overall survival.ConclusionsThe present data indicate that miR-221 and miR-222 directly regulate cell invasion by targeting TIMP3 and act as prognostic factors for glioma patients.

MiR-181d acts as a tumor suppressor in glioma by targeting K-ras and Bcl-2

PurposeRecently, several microRNAs (miRNAs) were reported to be involved in the modulation of glioma development. The aim of our study was to determine the effect of miR-181d on the growth of glioma and to investigate whether this growth is modulated by targeting K-ras and Bcl-2.MethodsReal-time PCR was used to analyze the expression of miR-181d in human glioma samples and glioma cell lines. Apoptosis, cell cycle, and proliferation (MTT) assays were performed to assess the phenotypic changes in glioma cells. Immunohistochemistry was used to determine the expression of K-ras and Bcl-2 in glioma tissues, and a luciferase reporter assay was carried out to confirm whether K-ras and Bcl-2 are direct targets of miR-181d. Western blotting was used to identify the potential signaling pathways affected glioma cell growth by miR-181d. In vivo, xenograft tumors were examined for an anti-glioma effect of miR-181d.ResultsMiR-181d was down-regulated in human glioma samples and up-regulated in transfected glioma cells. Ectopic expression of miR-181d suppressed proliferation and triggered cell cycle arrest and apoptosis in glioma cell lines. K-ras and Bcl-2 were identified as direct targets of miR-181d and were up-regulated in glioma samples. The results showed evidence linking the tumor suppressor activity of miR-181d in glioma cells with the K-ras-related PI3K/AKT and MAPK/ERK pathways. Furthermore, xenograft tumors from miR-181d-treated U251 cells were suppressed in vivo.ConclusionMiR-181d may act as a glioma suppressor by targeting K-ras and Bcl-2.

Overexpression of osteopontin induces angiogenesis of endothelial progenitor cells via the avβ3/PI3K/AKT/eNOS/NO signaling pathway in glioma cells

Angiogenesis, a hallmark of tumor growth, is regulated by various angiogenic factors. Recent studies have shown that osteopontin (OPN) is a secreted, integrin-binding protein that contributes to glioma progression. However, its effect on the angiogenesis of gliomas is not fully understood. To elucidate the role of OPN in the process of glioma angiogenesis, endothelial progenitor cells (EPCs) were treated with conditioned media of human glioma SHG44 cells overexpressing OPN. Here, we identified that OPN secreted by glioma cells accelerated EPCs angiogenesis in vitro, including proliferation, migration, and tube formation. OPN also induced the activation of AKT and endothelial nitric oxide synthase (eNOS) and increased NO production without affecting the expression of VEGF, VEGFR-1, or VEGFR-2. Moreover, the avβ3 antibody, the PI3-K inhibitor LY294002 and the eNOS inhibitor NMA suppressed the OPN-mediated increase in NO production and angiogenesis in EPCs. Taken together, these results demonstrate that OPN directly stimulates angiogenesis via the avβ3/PI3-K/AKT/eNOS/NO signaling pathway and may play an important role in tumorigenesis by enhancing angiogenesis in gliomas.

Clinical significance of Hiwi gene expression in gliomas

Piwi, highly conserved during evolution, has been reported to play a key role in stem cell self-renewal in several different organisms. As one of the four human homologues of the Piwi family, Hiwi has been demonstrated to be significantly overexpressed in some human cancer. However, the relationship between Hiwi and human gliomas is unclear. In this study, we investigated the clinical significance of Hiwi in human gliomas. Hiwi was found to be specifically expressed in the majority of glioma tissues, and the expression was greatly increased with the ascending of tumor grades. In addition, it was statistically significant that the patients with high Hiwi positive had poorer outcome than the patients with low Hiwi positive. Our results suggest that Hiwi may be a critical factor in glioma progression and could be used as a potential molecular marker for pathological diagnosis and prognosis evaluation for malignant gliomas.

High β-catenin/Tcf-4 activity confers glioma progression via direct regulation of AKT2 gene expression

Recent data suggest that the β-catenin/Tcf-4 signaling pathway plays an important role in human cancer tumorigenesis. However, the mechanism of β-catenin/Tcf-4 signaling in tumorigenesis is poorly understood. In this study, we show that Tcf-4 protein levels were significantly elevated in high-grade gliomas in comparison with low-grade gliomas and that Tcf-4 levels correlated with levels of AKT2. Reduction of β-catenin/Tcf-4 activity inhibited glioma cell proliferation and invasion in vitro and tumor growth in vivo. This effect of β-catenin/Tcf-4 activity was mediated by AKT2, and in vivo binding of β-catenin/Tcf-4 to the AKT2 promoter was validated using the chromatin immunoprecipitation assay and luciferase reporter assays. Taken together, we have demonstrated that Tcf-4 is associated with glioma progression and that AKT2 is a new member of the genes that are regulated by β-catenin/Tcf-4.

MiR‐21 Modulates hTERT Through a STAT3‐Dependent Manner on Glioblastoma Cell Growth

As an important oncogenic miRNA, miR‐21 has been reported to play crucial roles in glioblastoma (GBM) carcinogenesis. However, the precise biological function and molecular mechanism of miR‐21 in GBM remain elusive. This study is designed to explore the mechanism of miR‐21 involved in the control of GBM cell growth.

Long noncoding RNA profiles reveal three molecular subtypes in glioma.

Gliomas are the most lethal type of primary brain tumor in adult. Long noncoding RNAs (lncRNAs), which are involved in the progression of various cancers, may offer a potential gene therapy target in glioma.

Overexpressed let-7a inhibits glioma cell malignancy by directly targeting K-ras, independently of PTEN

BACKGROUND Altered expression of micro(mi)RNAs has been shown to be associated with tumorigenesis and tumor progression. The expression of phosphatase and tensin homolog (PTEN) plays an important role in glioma and is regarded as a prognostic marker of glioma patients. The goal of this study was to investigate the function of lethal (let)-7a miRNA in glioma cell lines with different PTEN phenotypes. METHODS One hundred ninety-eight glioma tissues were used to profile miRNA expression. RESULTS Let-7a was shown to have lower expression in high-grade glioma than in low-grade glioma. Low expression of let-7a was correlated with poor prognosis of primary glioblastoma patients. We demonstrated that K-ras was a functional target for let-7a to induce cell cycle arrest, apoptosis, and inhibition of cell migration and invasion in vitro. Our further results showed no difference in malignancy inhibition induced by let-7a in 4 glioma cells, including U87 (PTEN null), U251 (PTEN mutant), LN229 (PTEN wild type), and LN229 (PTEN small interfering RNA). The phosphatidylinositol-3 kinase/Akt and mitogen-activated protein kinase/extracellular signal-regulated kinase pathways were inhibited by let-7a, and the inhibition effects had no difference in 4 glioma cells. We demonstrated that let-7a could induce suppression of glioma in vivo by generating a glioma xenograft model. CONCLUSION Our results indicated that let-7a suppresses its target transcript K-ras and inhibits glioma malignancy independent of PTEN expression.