MicroRNA in Human Glioma

MicroRNA-124-3p targets Sp1 transcription factor to regulate glioma progression in rats

Gliomas are the most prevalent malignancies of the central nervous system (CNS). Downregulation of microRNA‑124 (miR‑124) has been identified in glioma; however, its biological functions in glioma are not yet fully understood. Specificity protein 1 (SP1) is a type of transcription factor that is involved in cancer progression. In this study, we examined the targeting of Sp1 mRNA by miR-124-3p in a rat glioma model. After confirming and selecting the binding of Sp1 to miR-124 with the help of bioinformatics methods, adult male Wistar rats were used to induce glioma by microinjection of 1 × 106 C6 cells into the striatum area of brain. The rats were divided into 3 groups; intact, sham and glioma groups. The presence of glioma was confirmed 21 days after implantation through histological analysis. The expression levels of miR-124 and SP1 genes in the experimental groups were examined using quantitative real-time polymerase chain reaction (qRT-PCR). Our data showed that the expression of miR-124 was significantly downregulated in glioma group compared to the sham and intact group, while the expression of SP1 was significantly upregulated. We found that the expression levels of miR-124 and Sp1 were decreased and increased in C6 cell line compared to the normal brain tissue cell line, respectively. The results indicated that Sp1 was identified as a direct target of miR‑124 through luciferase reporter assays. In summary, this study demonstrated for the first time that miR-124 expression is downregulated and Sp1 expression is upregulated in an animal model of glioma, which, in turn, may be involved in the development of glioma brain cancer.

MicroRNA as a potential diagnostic and prognostic biomarker in brain gliomas: a systematic review and meta-analysis

Introduction

Brain neoplasms and central nervous system (CNS) disorders, particularly gliomas, have shown a notable increase in incidence over the last three decades, posing significant diagnostic and therapeutic challenges. MicroRNAs (miRNAs) have emerged as promising biomarkers due to their regulatory role in gene expression, offering potential enhancements in glioma diagnosis and prognosis.

Methods

This systematic review and meta-analysis, adhering to PRISMA guidelines, included 25 studies for diagnostic accuracy and 99 for prognostic analysis, published until August 27th, 2023. Studies were identified through comprehensive searches of PubMed, Web of Science, and Scopus databases. Inclusion criteria encompassed peer-reviewed original research providing sensitivity, specificity, and area under the curve (AUC) for miRNAs in glioma diagnosis, as well as survival outcomes with hazard ratios (HRs) or mean survival.

Results and discussion

Meta-analysis demonstrated miRNAs' high diagnostic accuracy, with a pooled sensitivity of 0.821 (95% CI: 0.781-0.855) and specificity of 0.831 (95% CI: 0.792-0.865), yielding an AUC of 0.893. Subgroup analysis by specimen type revealed consistent accuracy across blood, cerebrospinal fluid (CSF), and tissue samples. Our results also showed miRNAs can be potential prognostic biomarkers. miRNAs showed significant associations with overall survival (OS) (pooled HR: 2.0221; 95% CI: 1.8497-2.2105), progression-free survival (PFS) (pooled HR: 2.4248; 95% CI: 1.8888-3.1128), and disease-free survival (DFS) (pooled HR: 1.8973; 95% CI: 1.1637-3.0933) in tissue specimens. These findings underscore miRNAs' potential as valuable biomarkers for improving glioma diagnosis and prognosis, offering insights for enhancing clinical decision-making and patient outcomes.

The evidence for repurposing anti-epileptic drugs to target cancer

Antiepileptic drugs are versatile drugs with the potential to be used in functional drug formulations with drug repurposing approaches. In the present review, we investigated the anticancer properties of antiepileptic drugs and interlinked cancer and epileptic pathways. Our focus was primarily on those drugs that have entered clinical trials with positive results and those that provided good results in preclinical studies. Many contributing factors make cancer therapy fail, like drug resistance, tumor heterogeneity, and cost; exploring all alternatives for efficient treatment is important. It is crucial to find new drug targets to find out new antitumor molecules from the already clinically validated and approved drugs utilizing drug repurposing methods. The advancements in genomics, proteomics, and other computational approaches speed up drug repurposing. This review summarizes the potential of antiepileptic drugs in different cancers and tumor progression in the brain. Valproic acid, oxcarbazepine, lacosamide, lamotrigine, and levetiracetam are the drugs that showed potential beneficial outcomes against different cancers. Antiepileptic drugs might be a good option for adjuvant cancer therapy, but there is a need to investigate further their efficacy in cancer therapy clinical trials.

Circular RNA circ_0000212 accelerates cervical cancer progression by acting as a miR-625-5p sponge to upregulate PTP4A1

Cervical cancer is one of the most common malignant tumors in women. Circular RNA (circRNA) has been shown to play a crucial role in cervical cancer. Here, the aim of this study was to explore the functions and a novel miRNA/mRNA network underlying circ_0000212 in cervical cancer regulation. The expression of circ_000212, miR-625-5p and Protein Tyrosine Phosphatase 4A1 (PTP4A1) mRNA was measured by quantitative real-time PCR (qRT-PCR). 5-ethynyl-2'-deoxyuridine assay was conducted to detect the proliferation of cervical cancer cells. Wound healing and transwell assays were employed to assess cell migration and invasion. The angiogenesis abilities of cervical cancer cells were evaluated by tube formation assay. Flow cytometry was performed for analyzing cell apoptosis. The expression of PTP4A1 protein and apoptosis-relative protein were detected via western blot. The dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed to clarify the interaction between circ_0000212 or PTP4A1 and miR-625-5p. The impact of circ_0000212 on cervical cancer growth in vivo was detected by xenograft assay. Circ_0000212 and PTP4A1 were highly expressed and miR-625-5p expression level was decreased in cervical cancer. Circ_0000212 silencing suppressed cervical cancer cell proliferation, migration, invasion and angiogenesis while promoting apoptosis. MiR-625-5p was targeted by circ_0000212, and miR-625-5p inhibition reversed the effects of circ_0000212 knockdown. MiR-625-5p directly targeted PTP4A1, and the inhibitory effect of miR-625-5p on the malignant progression of cervical cancer was reversed after PTP4A1 overexpression. In-vivo assays validated that circ_0000212 promoted cervical cancer tumor growth in vivo . circ_0000212 acted as an oncogene in cervical cancer progression, and knockdown of circ_0000212 repressed cervical cancer development by increasing miR-625-5p and decreasing PTP4A1.

The role of microRNA-induced apoptosis in diverse radioresistant cancers

Resistance to cancer radiotherapy is one of the biggest concerns for success in treating and preventing recurrent disease. Malignant tumors may develop when they block genetic mutations associated with apoptosis or abnormal expression of apoptosis; Tumor treatment may induce the expression of apoptosis-related genes to promote tumor cell apoptosis. MicroRNAs have been shown to contribute to forecasting prognosis, distinguishing between cancer subtypes, and affecting treatment outcomes in cancer. Constraining these miRNAs may be an attractive treatment strategy to help overcome radiation resistance. The delivery of these future treatments is still challenging due to the excess downstream targets that each miRNA can control. Understanding the role of miRNAs brings us one step closer to attaining patient treatment and improving patient outcomes. This review summarized the current information on the role of microRNA-induced apoptosis in determining the radiosensitivity of various cancers.

MicroRNAs as prognostic markers and therapeutic targets in gliomas

Gliomas are invasive brain tumors characterized by high rates of recurrence and mortality. Glioblastoma (GBM), a grade IV brain tumor, is known for its heterogenicity and its resistance to the current treatment regimen. MicroRNA (miRNAs) are small non-coding sequences of RNA that regulate and influence the expression of multiple genes. The detection of certain types of micro-RNA in tissues and blood serum can be used for diagnosis and prognosis, including the response of a particular patient to therapy. The purpose of this review is to analyze studies and experimental results concerning changes in microRNA expression profiles characteristic of gliomas. Furthermore, miRNAs also contribute to autophagy at multiple stages. In this review, we summarize the functions of miRNAs in GBM pathways linked to dysregulation of cell cycle control, apoptosis and resistance to treatment, and the possible use of miRNAs in clinical settings as treatment and prediction biomarkers.

Circ_CLIP2 promotes glioma progression through targeting the miR-195-5p/HMGB3 axis

BACKGROUND

Circular RNA (circRNA) has been demonstrated to play key roles in regulating glioma progression. Understanding the regulatory mechanism of circRNA in glioma is vital to reveal the pathogenesis of glioma and develop novel therapeutic strategies. Therefore, our study focuses on the role and underlying mechanism of Circ_CLIP2 in glioma.

METHODS

The expression of Circ_CLIP2, miR-195-5p and HMGB3 in glioma cells and tissues were analyzed using qRT-PCR. Cell proliferation was determined with colony formation and MTT assays. Cell cycle and apoptosis were examined by flow cytometry. Western blot was conducted for analyzing HMGB3, PCNA, Bax, Bcl-2, cleaved-caspase 3, Wnt-1 and β-catenin. Dual-luciferase reporter assay was measured to investigate the interaction among Circ_CLIP2, miR-195-5p and HMGB3.

RESULTS

The expression of Circ_CLIP2 and HMGB3 were increased while miR-195-5p was down-regulated in glioma cells and patients. Silencing of Circ_CLIP2 inhibited cell proliferation, enhanced cell apoptosis and inhibited the Wnt/β-catenin signaling pathway. Circ_CLIP2 suppressed miR-195-5p expression by directly sponging miR-195-5p. MiR-195-5p inhibited HMGB3 expression via directly targeting HMGB3. Knockdown of miR-195-5p facilitated cell proliferation, inhibited cell apoptosis and activated Wnt/β-catenin signaling, which were reversed by silencing of HMGB3.

CONCLUSION

Knockdown of Circ_CLIP2 suppresses glioma progression by targeting miR-195-5p/HMGB3 thus inhibiting Wnt/β-catenin signaling. This study may provide potential therapeutic targets against glioma.

Unique Interplay Between Molecular miR-181b/d Biomarkers and Health Related Quality of Life Score in the Predictive Glioma Models

In the last decade, an increasing amount of research has been conducted analyzing microRNA expression changes in glioma tissue and its expressed exosomes, but there is still sparse information on microRNAs or other biomarkers and their association with patients’ functional/psychological outcomes. In this study, we performed a combinational analysis measuring miR-181b and miR-181d expression levels by quantitative polymerase chain reaction (qPCR), evaluating isocitrate dehydrogenase 1 (IDH1) single nucleotide polymorphism (SNP), and O-6-methylguanine methyltransferase (MGMT) promoter methylation status in 92 post-surgical glioma samples and 64 serum exosomes, including patients’ quality of life evaluation applying European Organization for Research and Treatment of Cancer (EORTC) questionnaire for cancer patients (QLQ-30), EORTC the Brain Cancer-Specific Quality of Life Questionnaire (QLQ-BN20), and the Karnofsky performance status (KPS). The tumoral expression of miR-181b was lower in grade III and glioblastoma, compared to grade II glioma patients (p < 0.05). Additionally, for the first time, we demonstrated the association between miR-181 expression levels and patients’ quality of life. A positive correlation was observed between tumoral miR-181d levels and glioma patients’ functional parameters (p < 0.05), whereas increased exosomal miR-181b levels indicated a worse functional outcome (p < 0.05). Moreover, elevated miR-181b exosomal expression can indicate a significantly shorter post-surgical survival time for glioblastoma multiforme (GBM) patients. In addition, both tumoral and exosomal miR-181 expression levels were related to patients’ functioning and tumor-related symptoms. Our study adds to previous findings by demonstrating the unique interplay between molecular miR-181b/d biomarkers and health related quality of life (HRQOL) score as both variables remained significant in the predictive glioma models.

MicroRNA-585 inhibits human glioma cell proliferation by directly targeting MDM2

Background

MicroRNAs (miRNAs) are important regulators for cancer cell proliferation. miR-585 has been shown to inhibit the proliferation of several types of cancer, however, little is known about its role in human glioma cells.

Methods

miR-585 levels in human glioma clinical samples and cell lines were examined by quantitative real-time PCR (qRT-PCR) analysis. Cell proliferation was measured by Cell Counting Kit-8 (CCK-8) and EdU incorporation assays in vitro. For in vivo investigations, U251 cells were intracranially inoculated in BALB/c nude mice and xenografted tumors were visualized by magnetic resonance imaging (MRI).

Results

miR-585 expression is downregulated in human glioma tissues and cell lines compared with non-cancerous counterparts. Additionally, miR-585 overexpression inhibits and its knockdown promotes human glioma cell proliferation in vitro. Moreover, miR-585 overexpression also inhibits the growth of glioma xenografts in vivo, suggesting that miR-585 may act as a tumor suppressor to inhibit the proliferation of human glioma. Furthermore, miR-585 directly targets and decreases the expression of oncoprotein murine double minute 2 (MDM2). More importantly, the restoration of MDM2 via enforced overexpression markedly rescues miR-585 inhibitory effect on human glioma cell proliferation, thus demonstrating that targeting MDM2 is a critical mechanism by which miR-585 inhibits human glioma cell proliferation.

Conclusions

Our study unveils the anti-proliferative role of miR-585 in human glioma cells, and also implicates its potential application in clinical therapy.

Lnc00462717 regulates the permeability of the blood-brain tumor barrier through interaction with PTBP1 to inhibit the miR-186-5p/Occludin signaling pathway

Blood-brain tumor barrier (BTB) severely restricts the efficient delivery of chemotherapeutic drugs into brain tumor tissue, which is a critical obstacle for glioma treatment. Recently, long noncoding RNAs (lncRNAs) have shown as regulation factors of numerous biological processes. In this study, we identified that Lnc00462717 was upregulated in glioma endothelial cells (GECs), and that knockdown of Lnc00462717 significantly increased the BTB permeability. Both bioinformatics and RNA immunoprecipitation (RIP) results revealed that Lnc00462717 interacts with polypyrimidine tract binding protein (PTBP1). Moreover, overexpression of PTBP1 significantly reversed the increase in BTB permeability caused by siLnc00462717. Furthermore, the binding sites between miR-186 and PTBP1 as well as between miR-186 and 3'UTR of Occludin mRNA were confirmed by RIP and luciferase assays, respectively. And the interaction of Lnc00462717 and PTBP1 significantly facilitated the binding of PTBP1 to 3'UTR of Occludin mRNA and then blocked the miR-186-5p-induced downregulation of Occludin. In addition, we identified that knockdown of Lnc00462717 or overexpression of miR-186-5p increased the accumulation of doxorubicin (Dox) in brain glioma via the ultrafast liquid chromatography-mass spectrometry system (UFLC-MS/MS system) and decreased the intracranial glioma volume in BALB/c nude mice. Taken together, these results show a novel molecular pathway in BTB that may provide a potential innovative strategy for glioma therapy.

microRNAs and Markers of Neutrophil Activation as Predictors of Early Incidental Post-Surgical Pulmonary Embolism in Patients with Intracranial Tumors

Venous thromboembolism (VTE) is a common complication of cancer that severely increases morbidity and mortality. Patients with intracranial tumors are more likely to develop VTE than patients with cancers at other sites. Conversely, limited tools exist to identify patients with high thrombotic risk. Upon activation, neutrophils release their content through different mechanisms triggering thrombosis. We explored the ability of microRNAs (miRNAs) and plasma markers of neutrophil activation measured before surgery to predict the risk of early post-surgical pulmonary embolism (PE) in glioma and meningioma patients. We recruited and prospectively followed 50 patients with glioma and 50 with meningioma, 34% of whom in each group developed an early objectively-diagnosed post-surgical PE. We measured miRNA expression and neutrophil markers (cell-free DNA, nucleosomes, calprotectin and myeloperoxidase) before surgery. In glioma patients, we adjusted and validated a predictive model for post-surgical PE with 6 miRNAs: miR-363-3p, miR-93-3p, miR-22-5p, miR-451a, miR-222-3p and miR-140-3p (AUC = 0.78; 95% Confidence Interval (CI) [0.63, 0.94]) and another with cfDNA and myeloperoxidase as predictors (AUC = 0.71; 95% CI [0.52, 0.90]). Furthermore, we combined both types of markers and obtained a model with myeloperoxidase and miR-140-3p as predictors (AUC = 0.79; 95% CI [0.64, 0.94]). In meningioma patients we fitted and validated a predictive model with 6 miRNAs: miR-29a-3p, miR-660-5p, miR-331-3p, miR-126-5p, miR-23a-3p and miR-23b-3p (AUC = 0.69; 95% CI [0.52, 0.87]). All our models outperformed the Khorana score. This is the first study that analyzes the capability of plasma miRNAs and neutrophil activation markers to predict early post-surgical PE in glioma and meningioma patients. The estimation of the thrombotic risk before surgery may promote a tailored thromboprophylaxis in a selected group of high-risk patients, in order to minimize the incidence of PE and avoid bleedings.

MiRNA-7 Replacement Effect on Proliferation and Tarceva-Sensitivity in U373-MG Cell Line

BACKGROUND

Deregulation of the EGFR signaling pathway activity has been shown to can be effective in resistance to EGFR-TKIs, such as Tarceva (erlotinib), in glioblastoma cells. In addition, reports have shown that the reduction of miRNA-7 expression levels is associated with an increase in the expression of EGFR. Here, we evaluated the effect of miRNA-7 on EGFR expression and sensitivity of the U373-MG glioblastoma to erlotinib.

METHODS

The effect of miRNA-7 on EGFR expression was examined using RT-qPCR and western blotting. Trypan blue and MTT assays were performed to explore the effect of treatments on cell growth and survival, respectively. The combination index analysis was used to evaluate the interaction between drugs. Apoptosis was measured by ELISA cell death assay.

RESULTS

We showed that miRNA-7 markedly inhibited the expression of EGFR and decreased the growth of glioblastoma cells, relative to blank control and negative control miRNA (p < 0.05). Introduction of miRNA-7 synergistically increased the sensitivity of the U373-MG cells to erlotinib. Results of apoptosis assay demonstrated that miRNA-7 can trigger apoptosis and enhance the erlotinib-mediated apoptosis.

CONCLUSIONS

Our results show that miRNA-7 plays a critical role in the growth, survival and sensitivity of the U373-MG cells to erlotinib by targeting EGFR. Thus, miRNA-7 replacement therapy can become an effective therapeutic procedure in glioblastoma.

MiRNA-7 enhances erlotinib sensitivity of glioblastoma cells by blocking the IRS-1 and IRS-2 expression

Objectives

Down-regulation of miRNA-7 is correlated with over-expression of IRS-1 and IRS-2 proteins, the upstream regulators of IGF-1R/Akt pathway, in glioblastoma cells. In this study, the effect of miRNA-7 on expression of IRS-1 and IRS-2 and sensitivity of the U373-MG glioblastoma cells to erlotinib was explored.

Methods

After miRNA-7 transfection, the expression of IRS-1 and IRS-2 mRNAs was measured by RT-qPCR. Trypan blue assay was used to assess the effect of miRNA-7 on cell proliferation. The effects of miRNA-7 and erlotinib, alone and in combination, on cell survival and apoptosis were measured using MTT assay and ELISA cell death assay, respectively.

Key findings

Our data showed that miRNA-7 markedly inhibited the expression of IRS-1 and IRS-2 in a time-dependent manner, inhibited the proliferation of glioblastoma cells and enhanced apoptosis (P &lt; 0.05, relative to control). Pretreatment with miRNA-7 synergistically inhibited the cell survival rate and decreased the IC50 of erlotinib. Furthermore, miRNA-7 significantly augmented the apoptotic effect of erlotinib.

Conclusions

Our data propose that inhibition of IRS-1 and IRS-2 by miRNA-7 can effectively induce apoptosis and sensitize glioblastoma cell to EGFR-TKIs. Therefore, miRNA-7 may be a potential therapeutic target in patients with glioblastoma.

Decreased expression of miR-410-3p correlates with poor prognosis and tumorigenesis in human glioma

Background

Gliomas are the most common type of primary tumors in the central nervous system. This study aimed to investigate the biological role of miR-410-3p in glioma and elucidate the potential molecular mechanisms involved.

Methods

The expression levels of miR-410-3p in clinical tissue samples and glioma cell lines were determined using qRT-PCR analysis. The clinical significance of miR-410-3p in glioma was evaluated using Kaplan-Meier survival analysis and Fisher’s exact test. The effects of miR-410-3p on glioma cell proliferation, apoptosis, migration and invasion were investigated using MTT assays, flow cytometry, transwell migration and invasion assays. Besides, corresponding mechanistic studies were carried out.

Results

miR-410-3p was significantly down-regulated in glioma tissues. Besides, Kaplan-Meier analysis demonstrated that patients with low miR-410-3p expression had a shorter overall survival. Decreased miR-410-3p expression was associated with larger tumor size, lower Karnofsky performance score (KPS), and higher World Health Organization (WHO) grade. Over-expression of miR-410-3p suppressed cell proliferation, migration, and invasion, and accelerated apoptosis; whereas depletion of miR-410-3p facilitated cell proliferation, migration, and invasion, and inhibited apoptosis. Mechanistic investigations demonstrated that Ras-related protein 1A (RAP1A) was a direct target of miR-410-3p, and that rescue of RAP1A expression reversed miR-410-3p over-expression-induced inhibitory effects on cell proliferation, migration, and invasion. Notably, miR-410-3p over-expression repressed tumor growth in mouse xenograft models.

Conclusion

Our findings indicate that miR-410-3p functions as a tumor suppressor in glioma by directly targeting RAP1A. Thus, this study may provide some new insights into gliomagenesis and progression.

Extracellular Vesicles in Glioma: From Diagnosis to Therapy

Increasing evidence indicates that extracellular vesicles (EVs) secreted from tumor cells play a key role in the overall progression of the disease state. EVs such as exosomes are secreted by a wide variety of cells and transport a varied population of proteins, lipids, DNA, and RNA species within the body. Gliomas constitute a significant proportion of all primary brain tumors and majority of brain malignancies. Glioblastoma multiforme (GBM) represents grade IV glioma and is associated with very poor prognosis despite the cumulative advances in diagnostic procedures and treatment strategies. Here, the authors describe the progress in understanding the role of EVs, especially exosomes, in overall glioma progression, and how new research is unraveling the utilities of exosomes in glioma diagnostics and development of next-generation therapeutic systems. Finally, based on an understanding of the latest scientific literature, a model for the possible working of therapeutic exosomes in glioma treatment is proposed.

Artificial microenvironment of in vitro glioblastoma cell cultures changes profile of miRNAs related to tumor drug resistance

Purpose: The in vitro environment can influence not only the molecular background of glioblastoma drug-resistance and treatment efficiency, but also the mechanisms and pathways of cell death. Both crucial molecular pathways and the deregulation of miRNAs are thought to participate in tumor therapy-resistance. The aim of our study is to examine the potential influence of ex vivo conditions on the expression of miRNAs engaged in the machinery of tumor-drug resistance, since in vitro models are commonly used for testing new therapeutics.

Methods: Glioblastoma-derived cells, cultured under three different sets of conditions, were used as experimental models in vitro. The expression of 84 miRNAs relevant to brain tumorigenesis was evaluated by multi-miRNA profiling for initial tumors and their corresponding cultures. Finally, the expression of selected miRNAs related to temozolomide-resistance (miR-125b, miR-130a, miR-21, miR-221, miR-222, miR-31, miR-149, miR-210, miR-181a) was assessed by real-time PCR for each tumor and neoplastic cells in cultures.

Results: Our results demonstrate significant discrepancies in the expression of several miRNAs between tumor cells in vivo and in vitro, with miR-130a, miR-221, miR-31, miR-21, miR-222, miR-210 being the most marked. Also differences were observed between particular models in vitro. The results of computational analysis revealed the interplay between examined miRNAs and their targets involved in processes of glioblastoma chemosensitivity, including the genes relevant to temozolomide response (MGMT, PTEN, MDM2, TP53, BBC3A).

Conclusion: The artificial environment may influence the selective proliferation of cell populations carrying specific patterns of miRNAs and/or the phenotype of neoplastic cells (eg differentiation) by the action of molecular events including miRNAs. These phenomena may influence the tumor-responsiveness to particular drugs, disturbing the evaluation of their efficacy in vitro, with unpredictable results caused by the interdependency of molecular pathways.

LINC00470 Coordinates the Epigenetic Regulation of ELFN2 to Distract GBM Cell Autophagy

The epigenetics and genomics of glioblastoma (GBM) are complicated. Previous reports indicate that ELFN2 is widely distributed in the cerebral cortex neurons, striatum, and hippocampus cone and in granular cells. However, the function and mechanism of ELFN2, particularly in GBM, have rarely been explored. In this study, we identified ELFN2 as a new hypomethylation gene that acts as an oncogene in GBM. ELFN2 promoted cell autophagy by interacting with AurkA and eIF2α and inhibiting the activation of AurkA. We also demonstrated that aberrantly high ELFN2 expression is obtained due to hypomethylation of its promoter and abnormal miR-101 and LINC00470 expression in GBM. LINC00470 not only enhanced the expression of ELFN2 through adsorption of miR-101 but also affected the methylation level of ELFN2 by decreasing H3K27me3 occupancy. In addition, LINC00470 played a dominant role in the regulation of GBM cell autophagy, even though it upregulated ELFN2 expression. The results indicate that the combination of LINC00470 and ELFN2 has important significance for evaluating the prognosis of astrocytoma patients.

MiR-433-3p suppresses cell growth and enhances chemosensitivity by targeting CREB in human glioma

Previous studies reported that miR-433 exerts function widely in human tumorigenesis and development. Here, we further investigate the potential role of miR-433 in glioma. Quantitative real-time PCR demonstrated that miR-433-3p and miR-433-5p were low expressed in glioma tissues and cell lines. Functional studies suggested that the overexpression of miR-433-3p suppressed proliferation, induced apoptosis and inhibited invasion and migration of human glioma cells. But the growth and metastasis of glioma cells were not significantly influenced by overexpression of miR-433-5p. In a xenograft model, we also showed that miR-433-3p had an inhibitory effect on the growth of glioma. Bioinformatics coupled with luciferase and western blot assays revealed that CREB is a direct target of miR-433-3p, and the overexpression of CREB can rescue the phenotype changes induced by miR-433-3p overexpression. Besides, miR-433-3p could increase chemosensitivity of glioma to temozolomide by targeting CREB in vitro and in vivo. Taken together, these results suggest that miR-433-3p may function as a potential marker in diagnostic and therapeutic target for glioma.

Role of the microRNA 181 family in glioma development

MicroRNAs (miRNAs) are small, noncoding regulatory RNAs that regulate protein expression by reducing mRNA stability and/or translation, via base pairing with full or partial sequence‑complementary target mRNAs. Recent evidence indicates that miRNAs have roles as tumor suppressors and oncogenes. The members of the miRNA181 (miR181) family have been reported to be downregulated in early stage human glioma, and to be involved in glioma development. The current study demonstrated that all subtypes of the miRNA 181 family were downregulated at stages of human glioma, including miR181a1, a2, b1, b2, c and d. In the present study, the family members were detected by reverse transcription-quantitative polymerase chain reaction in glioma tissues of different stages. miR181c declined the most in the samples from patients with World Health Organization (WHO) grade I glioma. As glioma development progressed from grade I to IV, the expression of miRN181 family members continued to decline, with miR181b1 exhibiting the fastest decline rate. Furthermore, a lentivirus was used to overexpress miR181c in primary glioma cells; the result indicated that miR181c overexpression was able to significantly inhibit glioma cell proliferation. Thus, miR181 may be a useful biomarker for human glioma at early stages. Detection of the level of miR181 family members may be a potential method for glioma diagnosis, determining the tumor WHO grade and guiding clinical treatment.

MiRNA-154-5p inhibits cell proliferation and metastasis by targeting PIWIL1 in glioblastoma

MicroRNAs (miRNAs) play a critical role in glioblastoma initiation and progression. PIWIL1, a human homolog of the PIWI family, has a critical effect on glioblastoma progression. In present study, we found that the expression of miR-154-5p was significantly lower in glioblastoma. Our results suggested that the overexpression of miR-154-5p suppressed proliferation and metastasis, induced apoptosis, whereas inhibiting the expression of miR-154-5p significantly promoted proliferation and metastasis of glioblastoma. We further proved that miR-154-5p directly integrated with the 3'-UTR of PIWIL1 and reintroduction of PIWIL1 can rescue the phenotype changes induced by miR-154-5p. Taken together, our study reveals that miR-154-5p can counteract the malignant phenotypes of glioblastoma by targeting PIWIL1, which might be beneficial to reveal new therapeutic targets for glioblastoma.

miR-30a inhibits glioma progression and stem cell‑like properties by repression of Wnt5a

miR-30a has been found to be dysregulated in diverse cancers and involved in the regulation of tumor progression. However, there is scarce research on the role of miR-30a in glioma. In the present study, we assessed the expression level of miR-30a in glioma tissues and cell lines. The microRNA microarray analysis revealed low expression of miR-30a in glioma tissues and cells vs. the control. Furthermore, we found that stable miR-30a inhibited cell proliferation, G1 phase arrest and stem cell-like formation in glioma. Moreover, to investigate the molecular mechanism of miR-30a on glioma cell phenotypes, we identified Wnt5a as a new direct target gene for miR-30a by bioinformatic assay, luciferase assay and western blot analysis. Further functional studies suggested that miR-30a suppressed metastasis, sphere formation and glioma growth by targeting Wnt5a signal pathway. Collectively, our findings suggested for the first time that miR-30a may function as a tumor suppressor in glioma by targeting Wnt5a.

A Comprehensive Review of Genomics and Noncoding RNA in Gliomas

Glioblastoma (GBM) is the most malignant primary adult brain tumor. In spite of our greater understanding of the biology of GBMs, clinical outcome of GBM patients remains poor, as their median survival with best available treatment is 12 to 18 months. Recent efforts of The Cancer Genome Atlas (TCGA) have subgrouped patients into 4 molecular/transcriptional subgroups: proneural, neural, classical, and mesenchymal. Continuing efforts are underway to provide a comprehensive map of the heterogeneous makeup of GBM to include noncoding transcripts, genetic mutations, and their associations to clinical outcome. In this review, we introduce key molecular events (genetic and epigenetic) that have been deemed most relevant as per studies such as TCGA, with a specific focus on noncoding RNAs such as microRNAs (miRNA) and long noncoding RNAs (lncRNA). One of our main objectives is to illustrate how miRNAs and lncRNAs play a pivotal role in brain tumor biology to define tumor heterogeneity at molecular and cellular levels. Ultimately, we elaborate how radiogenomics-based predictive models can describe miRNA/lncRNA-driven networks to better define heterogeneity of GBM with clinical relevance.

The role of micro-RNA in the regulation of signal pathways in gliomas

Gliomas are invasive brain tumors with high rates of recurrence and mortality. Glioblastoma multiforme (GBM) is the most deadly form of glioma with nearly 100% rate of recurrence and unfavorable prognosis in patients. Micro-RNAs (miR) are the class of wide-spread short non-coding RNAs that inhibit translation via binding to the mRNA of target genes. The aim of the present review is to analyze recent studies and experimental results concerning aberrant expression profiles of miR, which target components of the signaling pathways Hedgehog, Notch, Wnt, EGFR, TGFb, HIF1a in glioma/glioblastoma. Particularly, the interactions of miR with targets of 2-hydroxyglutarate (the product of mutant isocytrate dehydrogenase, R132H IDH1, which is specific for the glioma pathogenesis) have been considered in the present review. Detecting specific miRNAs in tissue and serum may serve as a diagnostic and prognostic tool for glioma, as well as for predicting treatment response of an individual patient, and potentially serving as a mechanism for creating personalized treatment strategies

Effect of rs11614913 Polymorphism on Mature miR196a2 Expression and its Target Gene HOXC8 Expression in Human Glioma

miRNA polymorphisms are recently identified as a risk factor for various cancers, and it is associated with change in the expression of target genes in vitro. rs11614913 polymorphism in miR196a2 was associated with risk of glioma in Chinese population. In this study, we have evaluated the role of rs11614913 polymorphism and glioma risk in Indian population in 180 cases and controls. Seventy-two glioma tissue-blood pairs were also assessed for mutation in this SNP. Further, the effect of this polymorphism on mature miR196a2 expression and HOXC8 gene expression was analysed in 33 glioma tissue samples with different genotypes. Allelic discrimination assay was performed for genotyping and quantitative real time PCR for the expression of miR196a2 and HOXC8 gene. We could not find any association between rs11614913 polymorphism and glioma risk in Indian population. The rs11614913 genotyping of glioma tissue and blood pair revealed presence of mutations showing changes from C to T allele in majority of samples. The expression of the mature miR196a2 was significantly high in glioma samples, but there was no difference in expression with genotype. HOXC8 gene expression was not significantly different in glioma tissue when compared to non-glioma and interestingly there was a significant difference in expression with different genotypes, especially TT genotype was showing over expression when compared to other genotypes. Our study suggests that the rs11614913 polymorphism does not affect the mature miRNA expression, but shows its effect through target gene HOXC8 expression in glioma.

MicroRNA-34a inhibits cell proliferation and induces cell apoptosis of glioma cells via targeting of Bcl-2

Glioblastoma is a highly malignant brain tumor, characterized by the poor prognosis and high recurrence rates. Despite therapeutic strategies including surgery, radiotherapy and chemotherapy, the median survival of patients is only 14.6 months. MicroRNAs (miRNAs) have been considered as a novel type of gene regulator. Previous studies have demonstrated that the expression of miRNA‑34a (miR‑34a) is significantly associated with the grade and prognosis of glioma. However, the exact function of miR‑34a on glioma progression and underlying mechanisms remain to be elucidated. The present study investigated the function of miR‑34a in U87 human glioma cells by exogenously transfecting cells with an miR‑34a mimic. Overexpression of miR‑34a inhibited proliferation, and induced apoptosis of U87 cells. The current study also demonstrated that B‑cell lymphoma 2 (Bcl‑2) was the target gene of miR‑34a, as demonstrated by luciferase assays. Furthermore, restoring the expression of Bcl‑2 was indicated to partially block the miR‑34a‑induced apoptosis. Thus, data from the present study identified miR‑34a as a tumor suppressor in glioma by, at least partially, targeting Bcl‑2. This may provide future novel diagnostic and therapeutic strategies for human glioma.

Let-7f Inhibits Glioma Cell Proliferation, Migration, and Invasion by Targeting Periostin

Glioma is one of the most aggressive and malignant tumor types. Despite advances in surgery, imaging, chemotherapy, and radiation, glioma patient prognosis remains poor. Glioma pathogenesis is an urgent problem that must be solved. MicroRNAs (miRNAs) are endogenous small non-coding RNAs that are key post-transcriptional regulators of gene expression. miRNA deregulation commonly occurs in human tumorigenesis. In the present study, the expression levels of Let-7f were down-regulated in both glioma tissues and glioma cells. The enhanced expression of Let-7f suppressed glioma cells proliferation, migration, and invasion via direct targeting perisotin oncogenic activity. Experiments with periostin siRNA or over-expression further suggest that Let-7f may serve as tumor suppressors through perisotin signal. These findings provide insights regarding the role and mechanism of Let-7f in regulating biological behavior of glioma cells via the Let-7f/periostin axis, and Let-7f may serve as a potential therapeutic target in glioma.

Analysis of EZH2: micro-RNA network in low and high grade astrocytic tumors

Enhancer of Zeste homologue2 (EZH2) is an epigenetic regulator that functions as oncogene in astrocytic tumors, however, EZH2 regulation remains little studied. In this study, we measured EZH2 levels in low (Gr-II,DA) and high grade (Gr-IV,GBM) astrocytic tumors and found significant increased EZH2 transcript level with grade(median DA-8.5, GBM-28.9).However, a different trend was reflected in protein levels, with GBMs showing high EZH2 LI(median-26.5) compared to DA (median 0.3). This difference in correlation of EZH2 protein and RNA levels suggested post-transcriptional regulation of EZH2, likely mediated by miRNAs. We selected eleven miRNAs that strongly predicted to target EZH2 and measured their expression. Three miRNAs (miR-26a-5p,miR27a-3p and miR-498) showed significant correlation with EZH2 protein, suggesting them as regulators of EZH2, however miR-26a-5p levels decreased with grade. ChIP analyses revealed H3K27me3 modifications in miR-26a promoter suggesting feedback loop between EZH2 and miR26a. We further measured six downstream miRNA targets of EZH2 and found significant downregulation of four (miR-181a/b and 200b/c) in GBM. Interestingly, EZH2 associated miRNAs were predicted to target 25 genes in glioma-pathway, suggesting their role in tumor formation or progression. Collectively, our work suggests EZH2 and its miRNA interactors may serve as promising biomarkers for progression of astrocytic tumors and may offer novel therapeutic strategies.

The challenges and the promise of molecular targeted therapy in malignant gliomas

Malignant gliomas are the most common malignant primary brain tumors and one of the most challenging forms of cancers to treat. Despite advances in conventional treatment, the outcome for patients remains almost universally fatal. This poor prognosis is due to therapeutic resistance and tumor recurrence after surgical removal. However, over the past decade, molecular targeted therapy has held the promise of transforming the care of malignant glioma patients. Significant progress in understanding the molecular pathology of gliomagenesis and maintenance of the malignant phenotypes will open opportunities to rationally develop new molecular targeted therapy options. Recently, therapeutic strategies have focused on targeting pro-growth signaling mediated by receptor tyrosine kinase/RAS/phosphatidylinositol 3-kinase pathway, proangiogenic pathways, and several other vital intracellular signaling networks, such as proteasome and histone deacetylase. However, several factors such as cross-talk between the altered pathways, intratumoral molecular heterogeneity, and therapeutic resistance of glioma stem cells (GSCs) have limited the activity of single agents. Efforts are ongoing to study in depth the complex molecular biology of glioma, develop novel regimens targeting GSCs, and identify biomarkers to stratify patients with the individualized molecular targeted therapy. Here, we review the molecular alterations relevant to the pathology of malignant glioma, review current advances in clinical targeted trials, and discuss the challenges, controversies, and future directions of molecular targeted therapy.

MicroRNAs and Chinese Medicinal Herbs: New Possibilities in Cancer Therapy

In recent decades Chinese medicine has been used worldwide as a complementary and alternative medicine to treat cancer. Plenty of studies have shown that microRNAs (miRNAs) play fundamental roles in many pathological processes, including cancer, while the anti-cancer mechanisms of Chinese medicinal herbs targeting miRNAs also have been extensively explored. Our previous studies and those of others on Chinese medicinal herbs and miRNAs in various cancer models have provided a possibility of new cancer therapies, for example, up-regulating the expression of miR-23a may activate the positive regulatory network of p53 and miR-23a involved in the mechanism underlying the anti-tumor effect of berberine in hepatocellular carcinoma (HCC). In this review, we survey the role of Chinese medicinal herbal products in regulating miRNAs in cancer and the use of mediating miRNAs for cancer treatment. In addition, the controversial roles of herb-derived exogenous miRNAs in cancer treatment are also discussed. It is expected that targeting miRNAs would provide a novel therapeutic approach in cancer therapy by improving overall response and survival outcomes in cancer treatment, especially when combined with conventional therapeutics and Chinese medicinal herbal products.

Associations between SOX2 and miR-200b expression with the clinicopathological characteristics and prognosis of patients with glioma

The aim of the present study was to investigate the associations between microRNA (miR)-200b and sex determining region Y-box 2 (SOX2) expression with gender, age, clinical staging and pathological staging in 123 patients with glioma. The results revealed higher miR-200b expression levels in the glioma tissue than in the normal brain tissues, and a reduction in miR-200b expression with increasing pathological grading of the gliomas. Immunohistochemistry revealed a 53.7% gross expression rate of SOX2 in the glioma tissues. SOX2 and miR-200b expression levels were significantly correlated with the histological grading of the gliomas (P<0.05); however, no associations were observed with patient gender, age, pathological classification or clinical staging of the glioma (P>0.05). In patients with grade I and II gliomas, no correlation was detected between miR-200b and SOX2, while a significant correlation was observed in grade III and IV gliomas. A median 52-month follow-up revealed 1-, 3- and 5-year gross survival rates of 82.1, 50.0 and 30.7%, respectively, in the 123 patients with a glioma. Univariate analysis revealed no association between survival rate and patient age, gender, Karnofsky Performance Scale score, histological grading or clinical staging (P>0.05). However, miR-200b and SOX2 were independent prognostic factors for glioma (P<0.05). Patients with positive SOX2 expression exhibited a significantly reduced 5-year survival rate, compared with those with negative SOX2 expression (P<0.001). Furthermore, a significantly higher 5-year survival rate was observed in patients with high miR-200b expression than those with low miR-200b expression (P<0.001). The results indicated that SOX2 and miR-200b expression levels are associated with the histological grading of gliomas, but do not correlate with patient gender or age, or the pathological classification or clinical staging of the gliomas. Thus, miR-200b and SOX2 offer useful independent prognostic factors for glioma.

Serum microRNA-210 as a potential noninvasive biomarker for the diagnosis and prognosis of glioma

BACKGROUND

MicroRNA-210 (miR-210) is an oncogenic miRNA previously associated with prognosis in human gliomas, an incurable tumour type of the central nervous system. Here miR-210 was investigated as a potential serum biomarker in the diagnosis and prognosis of glioma.

METHODS

Serum was immediately prepared from blood samples collected from patients with glioma grades I-IV at primary diagnosis (n=136) and healthy controls (n=50) from February 2007 to March 2014 in the Department of Neurosurgery of the First Affiliated Hospital of Wannan Medical College (Wuhu, China). Total RNA was isolated from serum. cDNA was synthesised with primers specific for miR-210 and miR-16-1 (internal control), and quantitative real-time RT-PCR was performed. Results were statistically analysed to determine the role of miR-210 in the diagnosis and prognosis of human glioma patients.

RESULTS

An approximately seven-fold increase in miR-210 expression was detected in serum samples from glioblastoma patients relative to healthy controls. A threshold expression value (2.259) was chosen from receiver operator characteristic curves (ROC), and the low and high miR-210 expression groups were analysed by multivariate Cox proportional hazard regression and Kaplan-Meier analyses. Results revealed an association of high serum miR-210 expression with tumour grade and poor patient outcome (P-values <0.001).

CONCLUSIONS

Serum miR-210 is a promising diagnostic and prognostic biomarker that can be detected in the peripheral blood of patients with glioma.

MicroRNA-184 inhibits cell proliferation and invasion, and specifically targets TNFAIP2 in Glioma

Background

miRNA-184 is an oncogene in human hepatocellular carcinoma but acts as a tumor suppressor in tongue squamous cell carcinoma. Studies have shown that miR-184 was down-regulated in glioma and TNFα-induced protein 2 (TNFAIP2) was closely related to tumorigenesis. This study aimed to determine the functions of miR-184 in glioma and the mechanisms of miRNA-184-TNFAIP2 mediated glioma progression.

Methods

Real-time reverse-transcription PCR detected expression of miR-184 and TNFAIP2. U87 and U251 cells were transfected with miR-184 mimic, inhibitor, or negative control miRNA, and their invasion abilities were assayed. Cellular proliferation was measured by the cell counting kit-8 assay. miR-184 effects on glioma cell apoptosis and cell cycle were assessed by flow cytometer. Biological information software have predicted that miR-184 could target TNFα-induced protein 2 (TNFAIP2), Which was further validated by Western blot and qRT-PCR in glioma cells. In vivo, U87 cells transduced with either lentiviral over-expressed miR-184 or control lentivirus were injected into nude mice subcutaneously and intracranial respectively.

Results

Expression of miR-184 was significantly lower in glioma tissues and cell-lines compared to normal brain tissues. Protein and mRNA expression of TNFAIP2 were inversely correlated with miR-184 in glioma. In vitro, proliferation and invasion abilities were also decreased in U87 and U251 cells after transfection with miR-184 mimic. In vivo, the xenografted tumor size in the miR-184 overexpressing group were smaller than the miR-NC group. Concordantly, U87 and U251 cells transfected with miR-184 mimic had a higher apoptosis rate, triggering an accumulation of cells at the G0/G1 phase and decreased cells in S-phase.

Conclusions

miR-184 could regulate TNFAIP2 expression and affected its translation in glioma. miR-184 could also inhibit glioma progression and might serve as a novel therapeutic target in glioma.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0142-9) contains supplementary material, which is available to authorized users.

Current Therapeutic Advances Targeting EGFR and EGFRvIII in Glioblastoma

Epidermal growth factor receptor (EGFR) and EGFRvIII analysis is of current interest in glioblastoma – the most common malignant primary CNS tumor, because of new EGFRvIII vaccine trials underway. EGFR activation in glioblastoma promotes cellular proliferation via activation of MAPK and PI3K–Akt pathways, and EGFRvIII is the most common variant, leading to constitutively active EGFR. This review explains EGFR and EGFRvIII signaling in GBM; describes targeted therapy approaches to date including tyrosine kinase inhibitor, antibody-based therapies, vaccines and pre-clinical RNA-based therapies, and discusses the difficulties encountered with these approaches including pathway redundancy and intratumoral heterogeneity.

The methylation of a panel of genes differentiates low-grade from high-grade gliomas

Epigenetic changes play an important role in the pathogenesis of gliomas and have the potential to become clinically useful biomarkers. The aim of this study was the evaluation of the profile of promoter methylation of 13 genes selected based on their anticipated diagnostic and/or prognostic value. Methylation-specific PCR (MSP) was used to assess the methylation status of MGMT, ERCC1, hMLH1, ATM, CDKN2B (p15INK4B), p14ARF, CDKN2A (p16INK4A), RASSF1A, RUNX3, GATA6, NDRG2, PTEN, and RARβ in a subset of 95 gliomas of different grades. Additionally, the methylation status of MGMT and NDRG2 was analyzed using pyrosequencing (PSQ). The results revealed that the methylation index of individual glioma patients correlates with World Health Organization (WHO) tumor grade and patient's age. RASSF1A, RUNX3, GATA6, and MGMT were most frequently methylated, whereas the INK4B-ARF-INK4A locus, PTEN, RARβ, and ATM were methylated to a lesser extent. ERCC1, hMLH1, and NDRG2 were unmethylated. RUNX3 methylation correlated with WHO tumor grade and patient's age. PSQ confirmed significantly higher methylation levels of MGMT and NDRG2 as compared with normal, non-cancerous brain tissue. To conclude, DNA methylation of a whole panel of selected genes can serve as a tool for glioma aggressiveness prediction.

Identification of microRNAs as novel biomarkers for glioma detection: a meta-analysis based on 11 articles

BACKGROUND

Glioma is the most common and lethal primary brain tumors, and is regarded as one of the deadliest of human cancers. To date, a growing number of studies have tested the diagnostic accuracy of microRNAs (miRNAs) in glioma detection and altered levels of characteristic miRNAs have also been identified in glioma. However, there are some conflicting conclusions. Thus, we conducted this meta-analysis to evaluate the overall accuracy of miRNAs in the diagnosis of glioma.

METHODS

A comprehensive literature search was conducted using a combination of keywords. The random effect model was used to calculate the pooled diagnostic parameters. The summary receiver operator characteristic (SROC) curves were plotted to assess the overall diagnostic performance of miRNAs. Subgroup and sensitivity analyses were conducted to analyze the potential sources of heterogeneity.

RESULTS

In total, 28 studies from 11 articles covering 1729 patients and 1491 controls were available in this meta-analysis. The pooled sensitivity, specificity, PLR, NLR, DOR, and AUC were 0.87 (95% CI: 0.83-0.91), 0.87 (95% CI: 0.81-0.91), 6.6 (95% CI: 4.5-9.6), 0.15 (95% CI: 0.10-0.21), 45 (95% CI: 23-90), and 0.93 (95% CI: 0.91-0.95), respectively. Subgroup analysis demonstrated that panels of multiple miRNAs could largely improve the diagnostic accuracy. An independent meta-analysis of five included studies was conducted to evaluate the diagnostic efficacy of miR-21 in patients with glioma, with a pooled sensitivity of 0.82, specificity of 0.94, PLR of 13.2, NLR of 0.19, DOR of 69 and AUC of 0.95.

CONCLUSION

This meta-analysis indicated the great potential of miRNAs, especially panels of multiple miRNAs, as promising biomarkers in glioma detection and monitoring. As one of the most representative miRNAs, we also found that a single miR-21 could be a powerful clinical biomarker in glioma diagnosis.

MiR-21 up-regulation mediates glioblastoma cancer stem cells apoptosis and proliferation by targeting FASLG

To investigate whether miR-21 can affect the apoptosis and proliferation of glioblastoma cancer stem cells (GSCs) from down-regulating FASLG. The expression of miRNA-21 was detected by quantitative real-time PCR in normal brain tissue and glioblastoma samples, and the changes of miRNA-21 expression between GSCs and non-GSCs were also detected. The apoptosis and proliferation ability of miR-21 in GSCs were analyzed by MTT and flow cytometry assay after anti-miR-21 transfection. For the regulation mechanism analysis of miR-21, TargetScan, PicTar and microRNA were selected to predict some potential target genes of miR-21. The predicted gene was identified to be the direct and specific target gene of miR-21 by luciferase activities assay and western blot. RNA interference technology was used to confirm the apoptosis and proliferation effects of miR-21 were directly induced by FASLG. The expression of miR-21 increased significantly in glioblastoma contrast to normal brain tissue, and miR-21 up-regulated in GSCs remarkably. The proliferation of GSCs cell could be inhibited with high-expression of miR-21 and this effect could be restored by miR-21 knocked down. Mechanism analysis revealed that FASLG was a specific and direct target gene of miR-21. The advanced effects of anti-miR-21 on GSCs apoptosis and proliferation were mediated by expression of silenced FASLG. In summary, aberrantly expressed miR-21 regulates GSCs apoptosis and proliferation partly through directly down-regulating FASLG protein expression in GSCs and this might offer a new potential therapeutic stratagem for glioblastoma.

Identification of dysregulated miRNAs and their regulatory signature in glioma patients using the partial least squares method

Using microarray data, the present study identified differentially expressed microRNAs (miRNAs) and evaluated their regulatory characteristics in high-grade glioma patients, with the aim to further the understanding into the underlying etiology of the condition. Previously, studies have generally implemented regression or variance analysis, which ignores various background biological factors. However, in the present study, analysis was performed with microarray data collected from the Gene Expression Omnibus database using a partial least squares-based method, which is more sensitive in handling microarray data. Among the six identified differentially expressed miRNAs, hsa-miR-21 and hsa-miR-612 have been previously reported to be associated with glioma. In addition, the remaining miRNAs, hsa-miR-4680, hsa-miR-1908, hsa-miR-4656 and hsa-miR-4467, may also contribute to glioma progression since they are all associated with the tumorigenesis of other types of cancer. Moreover, the expression levels of hsa-miR-1908, hsa-miR-4656 and hsa-miR-4680 have been identified to significantly correlate with the survival rate. Enrichment analysis of the dysregulated target genes revealed that the selected miRNAs primarily affect biological processes in the nervous system and the protein phosphorylation process. Therefore, the results may offer a new understanding into the pathogenesis of high-grade glioma.

miR-96/HBP1/Wnt/β-catenin regulatory circuitry promotes glioma growth

We found that miR-96 is overexpressed in glioma, and its level inversely correlates with the survival of patients. The reduction in miR-96 abundance suppresses the proliferation and colony formation of glioma cells. The tumorigenicity of U-87 MG cells is reduced by miR-96 silencing. miR-96 contributes to the activation of Wnt/β-catenin pathway in glioma cells. HMG-box transcription factor 1 (HBP-1), a Wnt/β-catenin pathway inhibitor, is suppressed by miR-96. The reactivation of Wnt/β-catenin signaling causes an increase in the proliferation of glioma cells, and a decrease in miR-96 expression. On the other hand, HBP1 silencing promotes miR-96 expression. Collectively, miR-96 contributes to the progression of glioma by enhancing the activation of the Wnt/β-catenin pathway, and the miR-96/HBP1/Wnt/β-catenin regulatory circuitry promotes the proliferation of glioma cells.

Overexpression of microRNA-155 predicts poor prognosis in glioma patients

MicroRNA-155 is highly expressed in many malignant tumors with poor prognosis, which regulates cell apoptosis, proliferation, invasion, metastasis, tumor angiogenesis, and metabolism. This study aims at investigating the clinical significance of miR-155 expression in human gliomas. Real-time quantitative PCR was used to detect the expression levels of miR-155 in 131 glioma and 16 normal brain tissues. The association of miR-155 expression with clinicopathological factors and prognosis of glioma patients were analyzed. The expression levels of miR-155 were significantly higher in glioma tissues than that in normal brain tissues (P < 0.001), which was associated with high pathological grade (P < 0.001) and low Karnofsky Performance Status score (P = 0.022). As a result of Kaplan-Meier survival and Cox regression analyses, overall survival (OS) rates and progression-free survival were significantly poorer in high-expression group relative to low-expression group (both P < 0.001). Furthermore, miR-155 expression was significantly associated with poor OS (P < 0.001) and PFS (P = 0.001) in glioma patients who had high pathological grades (III-IV) as calculated by subgroup analyses. These findings reveal that miR-155 expression might be an independent prognostic factor and a therapeutic target for human glioma.