MicroRNA-155 promotes glioma cell proliferation via the regulation of MXI1

Methyltransferase METTL3-mediated maturation of miR-4654 facilitates high glucose-induced apoptosis and oxidative stress in lens epithelial cells via decreasing SOD2

N6-methyladenosine (m6 A) modification has been reported to have roles in modulating the development of diabetic cataract (DC). Methyltransferase-like 3 (METTL3) is a critical m6 A methyltransferase involving in m6 A modification activation. Here, we aimed to explore the action and mechanism of METTL3-mediated maturation of miR-4654 in DC progression. Human lens epithelial cells (HLECs) were exposed to high glucose (HG) to imitate DC condition in vitro. Levels of genes and proteins were tested via qRT-PCR and western blotting assays. The proliferation and apoptosis of HLECs were evaluated by cell counting kit-8, 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Oxidative stress was analyzed by detecting the contents of reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA). The binding of miR-4654 and SOD2 was confirmed by dual-luciferase reporter assay. The m6 A-RNA immunoprecipitation (MeRIP) assay detected the m6 A modification profile. Thereafter, we found that miR-4654 expression was elevated in DC samples and HG-induced HLECs. MiR-4654 knockdown reversed HG-mediated apoptosis and oxidative stress in HLECs. Mechanistically, miR-4654 directly targeted SOD2, silencing of SOD2 abolished the protective effects of miR-4654 knockdown on HLECs under HG condition. In addition, METTL3 induced miR-4654 maturation through promoting pri-miR-4654 m6 A modification, thereby increasing miR-4654 content in HLECs. METTL3 was highly expressed in DC samples and HG-induced HLECs, METTL3 deficiency protected HLECs against HG-mediated apoptotic and oxidative injury via down-regulating miR-4654. In all, METTL3 induced miR-4654 maturation in a m6 A-dependent manner, which was then reduced SOD2 expression, thus promoting apoptosis and oxidative stress in HLECs, suggesting a novel path for DC therapy.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Roles of the miR-155 in Neuroinflammation and Neurological Disorders: A Potent Biological and Therapeutic Target

Neuroinflammation plays a crucial role in the development and progression of neurological disorders. MicroRNA-155 (miR-155), a miR is known to play in inflammatory responses, is associated with susceptibility to inflammatory neurological disorders and neurodegeneration, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis as well as epilepsy, stroke, and brain malignancies. MiR-155 damages the central nervous system (CNS) by enhancing the expression of pro-inflammatory cytokines, like IL-1β, IL-6, TNF-α, and IRF3. It also disturbs the blood-brain barrier by decreasing junctional complex molecules such as claudin-1, annexin-2, syntenin-1, and dedicator of cytokinesis 1 (DOCK-1), a hallmark of many neurological disorders. This review discusses the molecular pathways which involve miR-155 as a critical component in the progression of neurological disorders, representing miR-155 as a viable therapeutic target.

Exosomal miR-155-5p derived from glioma stem-like cells promotes mesenchymal transition via targeting ACOT12

Tumor-associated exosomes play essential roles in intercellular communication and the foundation of cancer microenvironment in glioma. Many mRNAs, microRNAs (miRNAs) and proteins contained in tumor-associated exosomes can be transferred to recipient cells and contribute to the progression of tumor. Nevertheless, the cellular communication between malignant cells with different heterogeneities or characteristics and resultant tumor progression are still unclear in glioma. Here, we show that exosomes released from glioma stem-like cells (GSCs) contain a significant increasing level of miR-155-5p and could be horizontally transferred to surrounding glioma cells. High expression of miR-155-5p in plasma exosomes from patients was associated with glioma diagnosis and grading. Mechanically, we found that miR-155-5p markedly reduced the expression of acetyl-CoA thioesterase 12 (ACOT12), which played as a tumor suppressor in glioma. Furthermore, mesenchymal transition was significantly promoted in glioma cells treated with GSCs-derived exosomes. In conclusion, GSCs-derived exosomal miR-155-5p play a critical role in glioma progression and facilitating tumor aggressive growth by targeting ACOT12 and promoting mesenchymal transition. Exosomal miR-155-5p is also a potential predictive biomarker for glioma, which may provoke the development of novel diagnostic and therapeutic strategies against glioma.

Oxidative Stress and Inflammation in Cardiovascular Diseases and Cancer: Role of Non-coding RNAs

High oxidative stress, Th1/Th17 immune response, M1 macrophage inflammation, and cell death are associated with cardiovascular diseases. Controlled oxidative stress, Th2/Treg anti-tumor immune response, M2 macrophage inflammation, and survival are associated with cancer. MiR-21 protects against cardiovascular diseases but may induce tumor growth by retaining the anti-inflammatory M2 macrophage and Treg phenotypes and inhibiting apoptosis. Down-regulation of let-7, miR-1, miR-9, miR-16, miR-20a, miR-22a, miR-23a, miR-24a, miR-26a, miR-29, miR-30a, miR-34a, miR-124, miR-128, miR-130a, miR-133, miR-140, miR-143-145, miR-150, miR-153, miR-181a, miR-378, and miR-383 may aid cancer cells to escape from stresses. Upregulation of miR-146 and miR-223 may reduce anti-tumor immune response together with miR-21 that also protects against apoptosis. MiR-155 and silencing of let-7e, miR-125, and miR-126 increase anti-tumor immune response. MiR expression depends on oxidative stress, cytokines, MYC, and TGF-β, and expression of silencing lncRNAs and circ-RNAs. However, one lncRNA or circ-RNA may have opposite effects by targeting several miRs. For example, PVT1 induces apoptosis by targeting miR-16a and miR-30a but inhibits apoptosis by silencing miR-17. In addition, levels of a non-coding RNA in a cell type depend not only on expression in that cell type but also on an exchange of microvesicles between cell types and tumors. Although we got more insight into the function of a growing number of individual non-coding RNAs, overall, we do not know enough how several of them interact in functional networks and how their expression changes at different stages of disease progression.

Downregulation of long non-protein coding RNA MVIH impairs glioblastoma cell proliferation and invasion through an miR-302a-dependent mechanism

Glioblastoma (GB) is the most frequent and malignant type of brain tumor, for which no effective therapy exists. The high proliferative and invasive nature of GB, as well as its acquired resistance to chemotherapy, makes this type of cancer extremely lethal shortly after diagnosis. Long non-protein coding RNAs (lncRNA) are a class of regulatory RNAs whose levels can be dysregulated in the context of diseases, unbalancing several physiological processes. The lncRNA associated with microvascular invasion in hepatocellular carcinoma (lncRNA-MVIH), overexpressed in several cancers, was described to co-precipitate with phosphoglycerate kinase 1 (PGK1), preventing secretion of this enzyme to the extracellular environment and promoting cell migration and invasion. We hypothesized that, by silencing the expression of lncRNA-MVIH, the secretion of PGK1 would increase, reducing GB cell migration and invasion capabilities. We observed that lncRNA-MVIH silencing in human GB cells significantly decreased glycolysis, cell growth, migration, and invasion and sensitized GB cells to cediranib. However, no increase in extracellular PGK1 was observed as a consequence of lncRNA-MVIH silencing, and therefore, we investigated the possibility of a mechanism of miRNA sponge of lncRNA-MVIH being in place. We found that the levels of miR-302a loaded onto RISC increased in GB cells after lncRNA-MVIH silencing, with the consequent downregulation of several miR-302a molecular targets. Our findings suggest a new mechanism of action of lncRNA-MVIH as a sponge of miR-302a. We suggest that lncRNA-MVIH knockdown may be a promising strategy to address GB invasiveness and chemoresistance, holding potential towards its future application in a clinical context.

Extracellular Vesicles Loaded miRNAs as Potential Modulators Shared Between Glioblastoma, and Parkinson's and Alzheimer's Diseases

Glioblastoma (GBM) is the deadliest brain tumor. Its poor prognosis is due to cell heterogeneity, invasiveness, and high vascularization that impede an efficient therapeutic approach. In the past few years, several molecular links connecting GBM to neurodegenerative diseases (NDDs) were identified at preclinical and clinical level. In particular, giving the increasing critical role that epigenetic alterations play in both GBM and NDDs, we deeply analyzed the role of miRNAs, small non-coding RNAs acting epigenetic modulators in several key biological processes. Specific miRNAs, transported by extracellular vesicles (EVs), act as intercellular communication signals in both diseases. In this way, miRNA-loaded EVs modulate GBM tumorigenesis, as they spread oncogenic signaling within brain parenchyma, and control the aggregation of neurotoxic protein (Tau, Aβ-amyloid peptide, and α-synuclein) in NDDs. In this review, we highlight the most promising miRNAs linking GBM and NDDs playing a significant pathogenic role in both diseases.

Targeting AGTR1/NF-κB/CXCR4 axis by miR-155 attenuates oncogenesis in glioblastoma

Glioblastoma (GBM) represents the most aggressive malignancy of the central nervous system. Increased expression of Angiotensin II Receptor Type 1 (AGTR1) has been associated with proliferative and infiltrative properties of glioma cells. However, the underlying mechanism of AGTR1 upregulation in GBM is still unexplored. To understand the post-transcriptional regulation of AGTR1 in GBM, we screened 3'untranslated region (3'UTR) of AGTR1 for putative miRNA binding by using prediction algorithms. Interestingly, miR-155 showed conserved binding on the 3'UTR of AGTR1, subsequently confirmed by luciferase reporter assay. Furthermore, miR-155 overexpressing GBM cells show decrease in AGTR1 expression accompanied with reduced cell proliferation, invasion, foci formation and anchorage-independent growth. Strikingly, immunodeficient mice implanted with stable miR-155 overexpressing SNB19 cells show negligible tumor growth. Notably, miR-155 attenuates NF-κB signaling downstream of AGTR1 leading to reduced CXCR4 as well as AGTR1 levels. Mechanistically, miR-155 mitigates AGTR1-mediated angiogenesis, epithelial-to-mesenchymal transition, stemness, and MAPK signaling. Similar effects were observed by using pharmacological inhibitor of IκB Kinase (IKK) complex in multiple cell-based assays. Taken together, we established that miRNA-155 post-transcriptionally regulates AGTR1 expression, abrogates AGTR1/NF-κB/CXCR4 signaling axis and elicits pleiotropic anticancer effects in GBM. This study opens new avenues for using IKK inhibitors and miRNA-155 replacement therapies for the treatment of AGTR1-positive malignancies.

MiR-93/miR-375: Diagnostic Potential, Aggressiveness Correlation and Common Target Genes in Prostate Cancer

Dysregulation of miRNAs has a fundamental role in the initiation, development and progression of prostate cancer (PCa). The potential of miRNA in gene therapy and diagnostic applications is well documented. To further improve miRNAs’ ability to distinguish between PCa and benign prostatic hyperplasia (BPH) patients, nine miRNA (-21, -27b, -93, -141, -205, -221, -182, -375 and let-7a) with the highest reported differentiation power were chosen and for the first time used in comparative studies of serum and prostate tissue samples. Spearman correlations and response operating characteristic (ROC) analyses were applied to assess the capability of the miRNAs present in serum to discriminate between PCa and BPH patients. The present study clearly demonstrates that miR-93 and miR-375 could be taken into consideration as single blood-based non-invasive molecules to distinguish PCa from BPH patients. We indicate that these two miRNAs have six common, PCa-related, target genes (CCND2, MAP3K2, MXI1, PAFAH1B1, YOD1, ZFYVE26) that share the molecular function of protein binding (GO:0005515 term). A high diagnostic value of the new serum derived miR-182 (AUC = 0.881, 95% confidence interval, CI = 0.816–0.946, p < 0.0001, sensitivity and specificity were 85% and 79%, respectively) is also described.

FTO Inhibition Enhances the Antitumor Effect of Temozolomide by Targeting MYC-miR-155/23a Cluster-MXI1 Feedback Circuit in Glioma

Malignant glioma constitutes one of the fatal primary brain tumors in adults. Such poor prognosis calls for a better understanding of cancer-related signaling pathways of this disease. Here we elucidate a MYC-miRNA-MXI1 feedback loop that regulates proliferation and tumorigenesis in glioma. MYC suppressed MXI1 expression via microRNA-155 (miR-155) and the microRNA-23a∼27a∼24-2 cluster (miR-23a cluster), whereas MXI1, in turn, inhibited MYC expression by binding to its promoter. Overexpression of miR-155 and the miR-23a cluster promoted tumorigenesis in U87 glioma cells. Furthermore, fat mass and obesity-associated protein (FTO), an N⁶-methyladenosine (m⁶A) RNA demethylase, regulated the loop by targeting MYC. The ethyl ester form of meclofenamic acid (MA2) inhibited FTO and enhanced the effect of the chemotherapy drug temozolomide on suppressing proliferation of glioma cells and negatively regulated the loop. These data collectively highlight a key regulatory circuit in glioma and provide potential targets for clinical treatment. SIGNIFICANCE: These findings elucidate a novel feedback loop that regulates proliferation in glioma and can be targeted via inhibition of FTO to enhance the efficacy of temozolomide.

Emerging Roles and Potential Applications of Non-Coding RNAs in Glioblastoma

Non-coding RNAs (ncRNAs) comprise a diversity of RNA species, which do not have the potential to encode proteins. Non-coding RNAs include two classes of RNAs, namely: short regulatory ncRNAs and long non-coding RNAs (lncRNAs). The short regulatory RNAs, containing up to 200 nucleotides, include small RNAs, such as microRNAs (miRNA), short interfering RNAs (siRNAs), piwi-interacting RNAs (piRNAs), and small nucleolar RNAs (snoRNAs). The lncRNAs include long antisense RNAs and long intergenic RNAs (lincRNAs). Non-coding RNAs have been implicated as master regulators of several biological processes, their expression being strictly regulated under physiological conditions. In recent years, particularly in the last decade, substantial effort has been made to investigate the function of ncRNAs in several human diseases, including cancer. Glioblastoma is the most common and aggressive type of brain cancer in adults, with deregulated expression of small and long ncRNAs having been implicated in onset, progression, invasiveness, and recurrence of this tumor. The aim of this review is to guide the reader through important aspects of miRNA and lncRNA biology, focusing on the molecular mechanism associated with the progression of this highly malignant cancer type.

MiR-330-3p functions as a tumor suppressor that regulates glioma cell proliferation and migration by targeting CELF1

INTRODUCTION

Glioma is a common type of neoplasm that occurs in the central nervous system. miRNAs have been demonstrated to act as critical regulators of carcinogenesis and tumor progression in multiple cancers, but the molecular mechanism of miR-330-3p in glioma remained unclear. The purpose of the study was to explore the role of miR-330-3p in glioma cell reproduction and migration.

MATERIAL AND METHODS

The expression levels of miR-330-3p and CELF1 in 27 glioma tissue specimens and human glioma cell lines were examined by qRT-PCR and western blot. The TargetScan database was used to predict the relationship between miR-330-3p and CELF1. Then the target relationship was verified using dual-luciferase reporter assay. The effects of miR-330-3p/CELF1 on glioma cell proliferation were evaluated by MTT and colony formation assay. Wound healing assay was employed to measure the migration ability of glioma cells.

RESULTS

MiR-330-3p was found lowly expressed in glioma tissues and cells compared with adjacent tissues and normal astrocytes, while CELF1 expression was relatively high in the glioma tissues and cells. Dual-luciferase reporter assay confirmed that miR-330-3p could directly target CELF1. Furthermore, miR-330-3p could down-regulate the expression of CELF1, therefore suppressing glioma cell reproduction and migration.

CONCLUSIONS

MiR-330-3p inhibited the propagation and migration of glioma cells by repressing CELF1 expression.

Blocking lncRNA MIR155HG/miR-155-5p/-3p inhibits proliferation, invasion and migration of clear cell renal cell carcinoma

This study aimed to investigate the effect of blocking the MIR155HG/miR-155-5p/-3p axis on proliferation, invasion and migration of clear cell renal cell carcinoma. RT-qPCR was used to detect the expression of MIR155HG, miR-155-5p, miR-155-3p in clear cell renal cell carcinoma cell lines. To study the effects of blocking LncRNA MIR155HG and interfering with miR-155-5p and miR-155-3p on the biological function. The g proliferation of tumor was detected by CCK-8, and the cell invasion and migration abilities were detected by wound healing and transwell experiments. Western blot analyzed protein levels of KI67, PCNA, MMP2 and MMP9. Furthermore, TargetScan and miRDB were used to predict the co-target gene of miR-155-3p and miR-155-5p, and the functional analysis of co-target genes was performed using the DAVID. In the current research, the expression of MIR155HG was increased in ccRCC. Interference of MIR155HG inhibited the cellular functions of ccRCC cells, which was reversed by overexpression of miR-155-3p and miR-155-5p. In addition, MIR155HG interference repressed the expression of miR-155-5p and miR-155-3p in ccRCCs, while inhibition of miR-155-5p and miR-155-3p restrained the proliferation, invasion and migration of ccRCCs. Bioinformatics software analysis showed 13 co-targeting genes of miR-155-3p and miR-155-5p. Functional analysis presented that the target genes of miR-31-3p were involved in numerous of biochemical processes and pathways.Blocking lncRNA MIR155HG/miR-155-5p/-3p inhibits proliferation, invasion and migration of renal clear cell carcinoma, which provided a new method for early diagnosis and precise treatment of ccRCC.

Demonstrating specificity of bioactive peptide nucleic acids (PNAs) targeting microRNAs for practical laboratory classes of applied biochemistry and pharmacology

Practical laboratory classes teaching molecular pharmacology approaches employed in the development of therapeutic strategies are of great interest for students of courses in Biotechnology, Applied Biology, Pharmaceutic and Technology Chemistry, Translational Oncology. Unfortunately, in most cases the technology to be transferred to learning students is complex and requires multi-step approaches. In this respect, simple and straightforward experimental protocols might be of great interest. This study was aimed at presenting a laboratory exercise focusing (a) on a very challenging therapeutic strategy, i.e. microRNA therapeutics, and (b) on the employment of biomolecules of great interest in applied biology and pharmacology, i.e. peptide nucleic acids (PNAs). The aims of the practical laboratory were to determine: (a) the possible PNA-mediated arrest in RT-qPCR, to be eventually used to demonstrate PNA targeting of selected miRNAs; (b) the possible lack of activity on mutated PNA sequences; (c) the effects (if any) on the amplification of other unrelated miRNA sequences. The results which can be obtained support the following conclusions: PNA-mediated arrest in RT-qPCR can be analyzed in a easy way; mutated PNA sequences are completely inactive; the effects of the employed PNAs are specific and no inhibitory effect occurs on other unrelated miRNA sequences. This activity is simple (cell culture, RNA extraction, RT-qPCR are all well-established technologies), fast (starting from isolated and characterized RNA, few hours are just necessary), highly reproducible (therefore easily employed by even untrained students). On the other hand, these laboratory lessons require some facilities, the most critical being the availability of instruments for PCR. While this might be a problem in the case these instruments are not available, we would like to underline that determination of the presence or of a lack of amplified product can be also obtained using standard analytical approaches based on agarose gel electrophoresis.

Expression-based decision tree model reveals distinct microRNA expression pattern in pediatric neuronal and mixed neuronal-glial tumors

Background

The understanding of the molecular biology of pediatric neuronal and mixed neuronal-glial brain tumors is still insufficient due to low frequency and heterogeneity of those lesions which comprise several subtypes presenting neuronal and/or neuronal-glial differentiation. Important is that the most frequent ganglioglioma (GG) and dysembryoplastic neuroepithelial tumor (DNET) showed limited number of detectable molecular alterations. In such cases analyses of additional genomic mechanisms seem to be the most promising. The aim of the study was to evaluate microRNA (miRNA) profiles in GGs, DNETs and pilocytic asytrocytomas (PA) and test the hypothesis of plausible miRNA connection with histopathological subtypes of particular pediatric glial and mixed glioneronal tumors.

Methods

The study was designed as the two-stage analysis. Microarray testing was performed with the use of the miRCURY LNA microRNA Array technology in 51 cases. Validation set comprised 107 samples used during confirmation of the profiling results by qPCR bioinformatic analysis.

Results

Microarray data was compared between the groups using an analysis of variance with the Benjamini-Hochberg procedure used to estimate false discovery rates. After filtration 782 miRNAs were eligible for further analysis. Based on the results of 10 × 10-fold cross-validation J48 algorithm was identified as the most resilient to overfitting. Pairwise comparison showed the DNETs to be the most divergent with the largest number of miRNAs differing from either of the two comparative groups. Validation of array analysis was performed for miRNAs used in the classification model: miR-155-5p, miR-4754, miR-4530, miR-628-3p, let-7b-3p, miR-4758-3p, miRPlus-A1086 and miR-891a-5p. Model developed on their expression measured by qPCR showed weighted AUC of 0.97 (95% CI for all classes ranging from 0.91 to 1.00). A computational analysis was used to identify mRNA targets for final set of selected miRNAs using miRWalk database. Among genomic targets of selected molecules ZBTB20, LCOR, PFKFB2, SYNJ2BP and TPD52 genes were noted.

Conclusions

Our data showed the existence of miRNAs which expression is specific for different histological types of tumors. miRNA expression analysis may be useful in in-depth molecular diagnostic process of the tumors and could elucidate their origins and molecular background.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5739-5) contains supplementary material, which is available to authorized users.

MicroRNAs and Regeneration in Animal Models of CNS Disorders

microRNAs (miRNAs) are recently identified small RNA molecules that regulate gene expression and significantly influence the essential cellular processes associated with CNS repair after trauma and neuropathological conditions including stroke and neurodegenerative disorders. A number of specific miRNAs are implicated in regulating the development and propagation of CNS injury, as well as its subsequent regeneration. The review focuses on the functions of the miRNAs and their role in brain recovery following CNS damage. The article introduces a brief description of miRNA biogenesis and mechanisms of miRNA-induced gene suppression, followed by an overview of miRNAs involved in the processes associated with CNS repair, including neuroprotection, neuronal plasticity and axonal regeneration, vascular reorganization, neuroinflammation, and endogenous stem cell activation. Specific emphasis is placed on the role of multifunctional miRNA miR-155, as it appears to be involved in multiple neurorestorative processes during different CNS pathologies. In association with our own studies on miR-155, I introduce a new and unexplored approach to cerebral regeneration: regulation of brain tissue repair through a direct modulation of specific miRNA activity. The review concludes with discussion on the challenges and the future potential of miRNA-based therapeutic approaches to CNS repair.

Long noncoding RNAs: regulation, function and cancer

Long noncoding RNAs (lncRNAs) are non-protein-coding RNA transcripts that exert a key role in many cellular processes and have potential toward addressing disease etiology. Here, we review existing noncoding RNA classes and then describe a variety of mechanisms and functions by which lncRNAs regulate gene expression such as chromatin remodeling, genomic imprinting, gene transcription and post-transcriptional processing. We also examine several lncRNAs that contribute significantly to pathogenesis, oncogenesis, tumor suppression and cell cycle arrest of diverse cancer types and also give a summary of the pathways that lncRNAs might be involved in.

Blocking MIR155HG/miR-155 axis inhibits mesenchymal transition in glioma

Background

MIR155 host gene (MIR155HG) is a long noncoding RNA that has been considered as the primary micro (mi)RNA of miR-155. MIR155HG plays an essential role in hematopoiesis, inflammation, and tumorigenesis. Our study investigated the clinical significance, biological function, mechanisms, and small-molecule inhibitors of the MIR155HG/miR-155 axis in glioma.

Methods

We analyzed the expression of the MIR155HG/miR-155 axis and the correlation with glioma grade and patient survival using 2 different glioma gene expression datasets. Biological significance was elucidated through a series of in vitro and in vivo experiments. Furthermore, we conducted a high-throughput screening for small molecules to identify a potential inhibitor of the MIR155HG/miR-155 axis.

Results

Increased MIR155HG was associated with glioma grade, mesenchymal transition, and poor prognosis. Functionally, MIR155HG reduction by small interfering RNA inhibited cell proliferation, migration, invasion, and orthotopic glioma growth by repressing the generation of its derivatives miR-155-5p and miR-155-3p. Bioinformatics and luciferase reporter assays revealed that protocadherin 9 and protocadherin 7, which act as tumor suppressors by inhibiting the Wnt/β-catenin pathway, were direct targets of miR-155-5p and miR-155-3p, respectively. Finally, we identified NSC141562 as a potent small-molecule inhibitor of the MIR155HG/miR-155 axis.

Conclusions

Our results demonstrate that the MIR155HG/miR-155 axis plays a critical role in facilitating glioma progression and serves as a prognostic factor for patient survival in glioblastoma. High-throughput screening indicated that the MIR155HG/miR-155 axis inhibitor NSC141562 may be a useful candidate anti-glioma drug.

Multiplexed microRNA Expression Profiling by Combined Asymmetric PCR and Label-Free Detection using Silicon Photonic Sensor Arrays

Analysis methods based upon the quantitative, real-time polymerase chain reaction are extremely powerful; however, they face intrinsic limitations in terms of target multiplexing. In contrast, silicon photonic microring resonators represent a modularly multiplexable sensor array technology that is well-suited to the analysis of targeted biomarker panels. In this manuscript we employ an asymmetric polymerase chain reaction approach to selectively amplify copies of cDNAs generated from targeted miRNAs before multiplexed, label-free quantitation through hybridization to microring resonator arrays pre-functionalized with capture sequences. This method, which shows applicability to low input amounts and a large dynamic range, was demonstrated for the simultaneous detection of eight microRNA targets from twenty primary brain tumor samples with expression profiles in good agreement with literature precedent.

Silencing a Multifunctional microRNA Is Beneficial for Stroke Recovery

Stroke-induced endothelial cell injury leads to destruction of cerebral microvasculature and significant damage to the brain tissue. A subacute phase of cerebral ischemia is associated with regeneration involving the activation of vascular remodeling, neuroplasticity, neurogenesis, and neuroinflammation processes. Effective restoration and improvement of blood supply to the damaged brain tissue offers a potential therapy for stroke. microRNAs (miRNAs) are recently identified small RNA molecules that regulate gene expression and significantly influence the essential cellular processes associated with brain repair following stroke. A number of specific miRNAs are implicated in regulating the development and propagation of the ischemic tissue damage as well as in mediating post-stroke regeneration. In this review, I discuss the functions of the miRNA miR-155 and the effect of its in vivo inhibition on brain recovery following experimental cerebral ischemia. The article introduces new and unexplored approach to cerebral regeneration: regulation of brain tissue repair through a direct modulation of specific miRNA activity.

Prognostic relevance of miRNA-155 methylation in anaplastic glioma

The outcome of patients with anaplastic gliomas varies considerably depending on single molecular markers, such as mutations of the isocitrate dehydrogenase (IDH) genes, as well as molecular classifications based on epigenetic or genetic profiles. Remarkably, 98% of the RNA within a cell is not translated into proteins. Of those, especially microRNAs (miRNAs) have been shown not only to have a major influence on physiologic processes but also to be deregulated and prognostic in malignancies.To find novel survival markers and treatment options we performed unbiased DNA methylation screens that revealed 12 putative miRNA promoter regions with differential DNA methylation in anaplastic gliomas. Methylation of these candidate regions was validated in different independent patient cohorts revealing a set of miRNA promoter regions with prognostic relevance across data sets. Of those, miR-155 promoter methylation and miR-155 expression were negatively correlated and especially the methylation showed superior correlation with patient survival compared to established biomarkers.Functional examinations in malignant glioma cells further cemented the relevance of miR-155 for tumor cell viability with transient and stable modifications indicating an onco-miRNA activity. MiR-155 also conferred resistance towards alkylating temozolomide and radiotherapy as consequence of nuclear factor (NF)κB activation.Preconditioning glioma cells with an NFκB inhibitor reduced therapy resistance of miR-155 overexpressing cells. These cells resembled tumors with a low methylation of the miR-155 promoter and thus mir-155 or NFκB inhibition may provide treatment options with a special focus on patients with IDH wild type tumors.

S6K1 phosphorylation-dependent degradation of Mxi1 by β-Trcp ubiquitin ligase promotes Myc activation and radioresistance in lung cancer

Rationale: Mxi1 is regarded as a potential tumor suppressor protein that antagonizes the transcriptional activity of proto-oncogene Myc. However, the clinical significances and underlying mechanisms by which Mxi1 is regulated in lung cancer remain poorly understood.

Methods: Mass spectrometry analysis and immunoprecipitation assay were utilized to detect the protein-protein interaction. The phosphorylation of Mxi1 was evaluated by in vitro kinase assays. Poly-ubiquitination of Mxi1 was examined by in vivo ubiquitination assay. Lung cancer cells stably expressing wild-type Mxi1 or Mxi1-S160A were used for functional analyses. The expression levels of Mxi1 and S6K1 were determined by immunohistochemistry in lung cancer tissues and adjacent normal lung tissues.

Results: We found that Mxi1 is downregulated and correlated with poor prognosis in lung cancer. Using tandem affinity purification technology, we provided evidence that β-Trcp E3 ubiquitin ligase interacts with and promotes the ubiquitination and degradation of Mxi1. Furthermore, we demonstrated that Mxi1 is phosphorylated at S160 site by the protein kinase S6K1 and subsequently degraded via the ubiquitin ligase β-Trcp. Moreover, a phosphorylation mutant form of Mxi1 (Mxi1-S160A), which cannot be degraded by S6K1 and β-Trcp, is much more stable and efficient in suppressing the transcriptional activity of Myc and radioresistance in lung cancer cells. More importantly, a strong inverse correlation between S6K1 and Mxi1 expression was observed in human lung cancer tissues.

Conclusion: Our findings not only establish a crosstalk between the mTOR/S6K1 signaling pathway and Myc activation, but also suggest that targeting S6K1/Mxi1 pathway is a promising therapeutic strategy for the treatment of lung cancer.

Optimizing prognosis-related key miRNA-target interactions responsible for cancer metastasis

Increasing evidence suggests that the abnormality of microRNAs (miRNAs) and their downstream targets is frequently implicated in the pathogenesis of human cancers, however, the clinical benefit of causal miRNA-target interactions has been seldom studied. Here, we proposed a computational method to optimize prognosis-related key miRNA-target interactions by combining transcriptome and clinical data from thousands of TCGA tumors across 16 cancer types. We obtained a total of 1,956 prognosis-related key miRNA-target interactions between 112 miRNAs and 1,443 their targets. Interestingly, these key target genes are specifically involved in tumor progression-related functions, such as ‘cell adhesion’ and ‘cell migration’. Furthermore, they are most significantly correlated with ‘tissue invasion and metastasis’, a hallmark of metastasis, in ten distinct types of cancer through the hallmark analysis. These results implicated that the prognosis-related key miRNA-target interactions were highly associated with cancer metastasis. Finally, we observed that the combination of these key miRNA-target interactions allowed to distinguish patients with good prognosis from those with poor prognosis both in most TCGA cancer types and independent validation sets, highlighting their roles in cancer metastasis. We provided a user-friendly database named miRNATarget (freely available at http://biocc.hrbmu.edu.cn/miRNATar/), which provides an overview of the prognosis-related key miRNA-target interactions across 16 cancer types.

MicroRNAs in glioblastoma pathogenesis and therapy: A comprehensive review

Glioblastoma (GBM), also known as grade IV astrocytoma, is the most aggressive primary intracranial tumor of the adult brain. MicroRNAs (miRNAs), a class of small non-coding RNA species, have critical functions across various biological processes. A great deal of progress has been made recently in dissecting miRNA pathways associated with the pathogenesis of GBM. miRNA expression signatures called gene signatures also characterize and contribute to the phenotypic diversity of GBM subclasses through their ability to regulate developmental growth and differentiation. miRNA molecules have been identified as diagnostic and prognostic biomarkers for patient stratification and may also serve as therapeutic targets and agents. This review summarizes: (i) the current understanding of the roles of miRNAs in the pathogenesis of GBM, (ii) the potential use of miRNAs in GBM diagnosis and glioma grading, (iii) further prospects of developing miRNAs as novel biomarkers and therapeutic targets for GBM, and (iv) important practical considerations when considering miRNA therapy for GBM patients.

Nociceptin/orphanin FQ antagonizes lipopolysaccharide-stimulated proliferation, migration and inflammatory signaling in human glioblastoma U87 cells

Glioblastoma is among the most aggressive brain tumors and has an exceedingly poor prognosis. Recently, the importance of the tumor microenvironment in glioblastoma cell growth and progression has been emphasized. Toll-like receptor 4 (TLR4) recognizes bacterial lipopolysaccharide (LPS) and endogenous ligands originating from dying cells or the extracellular matrix involved in host defense and in inflammation. G-protein coupled receptors (GPCRs) have gained interest in anti-tumor drug discovery due to the role that they directly or indirectly play by transactivating other receptors, causing cell migration and proliferation. A proteomic analysis showed that the nociceptin receptor (NOPr) is among the GPCRs significantly expressed in glioblastoma cells, including U87 cells. We describe a novel role of the peptide nociceptin (N/OFQ), the endogenous ligand of the NOPr that counteracts cell migration, proliferation and increase in IL-1β mRNA elicited by LPS via TLR4 in U87 glioblastoma cells. Signaling pathways through which N/OFQ inhibits LPS-mediated cell migration and elevation of [Ca2+]i require β-arrestin 2 and are sensitive to TNFR-associated factor 6, c-Src and protein kinase C (PKC). LPS-induced cell proliferation and increase in IL-1β mRNA are counteracted by N/OFQ via β-arrestin 2, PKC and extracellular signal-regulated kinase 1/2; furthermore, the contributions of the transcription factors NF-kB and AP-1 were investigated. Independent of LPS, N/OFQ induces a significant increase in cell apoptosis. Contrary to what was observed in other cell models, a prolonged exposure to this endotoxin did not promote any tolerance of the cellular effects above described, including NOPr down-regulation while N/OFQ loses its inhibitory role.

Downregulation of SMARCB1/INI1 expression in pediatric chordomas correlates with upregulation of miR-671-5p and miR-193a-5p expressions

Loss of SMARCB1/INI1 expression is considered to be a hallmark for childhood chordomas (CCs). Although mutation/loss of 22q has strongly established the loss of SMARCB1/INI1 in cancers, the cause in CCs remains elusive. Recent studies suggest role of miRNAs in regulation of SMARCB1/INI1 expressions. We examined 5 reported/target predicted miRNAs to SMARCB1/INI1 in SMARCB1/INI1 immunonegative and immunopositive cases, and found upregulation of miR-671-5p and miR-193a-5p in SMARCB1/INI1-immunonegative cases. Notably, these two miRNAs were significantly predicted to target TGF-β signaling, suggestive of dysregulation of developmental and osteoblast regulation pathway in CCs. Overall, we suggest miR-671-5p- and miR-193a-5p-mediated epigenetic mode of SMARCB1/INI1 loss and downregulated TGF-β pathway in CCs.

miRNA Regulation in Gliomas: Usual Suspects in Glial Tumorigenesis and Evolving Clinical Applications

In recent years, an increasing role for noncoding small RNAs (miRNA) has been uncovered in carcinogenesis. These oligonucleotides can promote degradation and/or inhibit translation of key mRNAs. Recent studies have also highlighted a possible role for miRNAs in adult and pediatric brain tumors, including high- and low-grade gliomas, medulloblastoma, ependymoma, and neoplasms associated with neurofibromatosis type 1. Gliomas represent the most common category of primary intraparenchymal brain tumors, and, for example, manipulation of signaling pathways, through inhibition of PTEN transcription appears to be an important function of miRNA dysregulation through miR-21, miR-106b, and miR-26a. Moreover, altered miRNA expression in gliomas play roles in the regulation of common tumorigenic processes, including receptor tyrosine kinase signaling, angiogenesis, invasion, suppression of differentiation, cell cycle enhancement, and inhibition of apoptosis. Suppression of differentiation requires the downregulation of a number of miRNAs that are both enriched in the brain and required for terminal glial differentiation, including miR-219 and miR-338. Our evolving understanding about the biology of gliomas make them attractive for miRNA study, given that recent evidence suggests that epigenetic and subtle genetic changes may contribute to their pathogenesis. Identification of key miRNAs also provides a rationale for developing robust biomarkers and inhibitory RNA strategies for therapeutic purposes in glioma patients.

Mxi1-0 regulates the growth of human umbilical vein endothelial cells through extracellular signal-regulated kinase 1/2 (ERK1/2) and interleukin-8 (IL-8)-dependent pathways

Mxi1 plays an important role in the regulation of cell proliferation. Mxi1-0, a Mxi1 isoform, has a different N-terminal amino acid sequence, intracellular location and expression profile from Mxi1. However, the precise role of Mxi1-0 in cell proliferation and the molecular mechanism underlying its function remain poorly understood. Here, we showed that Mxi1-0 suppression decreased the proliferation of human umbilical vein endothelial cells (HUVECs) along with cell accumulation in the G2/M phase. Mxi1-0 suppression also significantly decreased the expression and secretion of interleukin (IL-8). Neutralizing IL-8 in conditioned medium (CM) from Mxi1-0-overexpressed HUVECs significantly eliminated CM-induced proliferation of HUVECs. In addition, Mxi1-0 suppression significantly decreased the activity of MAP kinase ERK1/2. Treatment of HUVECs with U0126, an ERK1/2 signaling inhibitor, attenuated autocrine production of IL-8 induced by Mxi1-0 overexpression. On the other hand, Mxi1-0 overexpression-induced IL-8 increased the level of phosphorylated ERK1/2 in HUVECs, and such increasing was diminished in cells incubated with CM, which neutralized with anti-IL-8 antibody. Taken together, our results suggest that Mxi1-0 regulates the growth of HUVECs via the IL-8 and ERK1/2 pathways, which apparently reciprocally activate each other.

An integrative analysis of DNA methylation in osteosarcoma

Background

The study aimed to analyze aberrantly methylated genes, relevant pathways and transcription factors (TFs) in osteosarcoma (OS) development.

Methods

Based on the DNA methylation microarray data GSE36002 that were downloaded from GEO database, the differentially methylated genes in promoter regions were identified between OS and normal samples. Pathway and function enrichment analyses of differentially methylated genes was performed. Subsequently, protein-protein interaction (PPI) network was constructed, followed by identification of cancer-associated differentially methylated genes and significant differentially methylated TFs.

Results

A total of 1379 hyper-methylation regions and 169 hypo-methylation regions in promoter regions were identified in OS samples compared to normal samples. The differentially hyper-methylated genes were significantly enriched in Neuroactive ligand-receptor interaction pathway, and Peroxisome proliferator activated receptor (PPAR) signaling pathway. The differentially hypo-methylated genes were significantly enriched in Toll-like receptor signaling pathway. In PPI network, signal transducers and activators of transcription (STAT3) had high degree (degree=21). MAX interactor 1, dimerization protein (MXI1), STAT3 and T-cell acute lymphocytic leukemia 1 (TAL1) were significant TFs enriched with target genes in OS samples. They were found to be cancer-associated and hyper-methylated in OS samples.

Conclusion

Neuroactive ligand-receptor interaction, PPAR signaling, Toll-like receptor signaling pathways are implicated in OS. MXI1, STAT3, and TAL1 may be important TFs involved in OS development.

Integration of MicroRNA, mRNA, and Protein Expression Data for the Identification of Cancer-Related MicroRNAs

MicroRNAs (miRNAs) are responsible for the regulation of target genes involved in various biological processes, and may play oncogenic or tumor suppressive roles. Many studies have investigated the relationships between miRNAs and their target genes, using mRNA and miRNA expression data. However, mRNA expression levels do not necessarily represent the exact gene expression profiles, since protein translation may be regulated in several different ways. Despite this, large-scale protein expression data have been integrated rarely when predicting gene-miRNA relationships. This study explores two approaches for the investigation of gene-miRNA relationships by integrating mRNA expression and protein expression data. First, miRNAs were ranked according to their effects on cancer development. We calculated influence scores for each miRNA, based on the number of significant mRNA-miRNA and protein-miRNA correlations. Furthermore, we constructed modules containing mRNAs, proteins, and miRNAs, in which these three molecular types are highly correlated. The regulatory interactions between miRNA and genes in these modules have been validated based on the direct regulations, indirect regulations, and co-regulations through transcription factors. We applied our approaches to glioblastomas (GBMs), ranked miRNAs depending on their effects on GBM, and obtained 52 GBM-related modules. Compared with the miRNA rankings and modules constructed using only mRNA expression data, the rankings and modules constructed using mRNA and protein expression data were shown to have better performance. Additionally, we experimentally verified that miR-504, highly ranked and included in the identified modules, plays a suppressive role in GBM development. We demonstrated that the integration of both expression profiles allows a more precise analysis of gene-miRNA interactions and the identification of a higher number of cancer-related miRNAs and regulatory mechanisms.

microRNA-137 promotes apoptosis in ovarian cancer cells via the regulation of XIAP

Background:

microRNAs (miRNAs) have regulatory roles in various cellular processes, including apoptosis. Recently, X-linked inhibitor of apoptosis protein (XIAP) has been reported to be dysregulated in epithelial ovarian cancer (EOC). However, the mechanism underlying this dysregulation is largely unknown.

Methods:

Using bioinformatics and a literature analysis, a panel of miRNAs dysregulated in EOC was chosen for further experimental confirmation from hundreds of miRNAs that were predicted to interact with the XIAP 3′UTR. A dual-luciferase reporter assay was employed to detect the interaction by cellular co-transfection of an miRNA expression vector and a reporter vector with the XIAP 3′UTR fused to a Renilla luciferase reporter. DAPI and TUNEL approaches were used to further determine the effects of an miR-137 mimic and inhibitor on cisplatin-induced apoptosis in ovarian cancer cells.

Results:

We identified eight miRNAs by screening a panel of dysregulated miRNAs that may target the XIAP 3′UTR. The strongest inhibitory miRNA, miR-137, suppressed the activity of a luciferase reporter gene fused with the XIAP 3′UTR and decreased the levels of XIAP protein in SKOV3 ovarian cancer cells. Furthermore, forced expression of miR-137 increased cisplatin-induced apoptosis, and the depressed expression of miR-137 decreased cisplatin-induced apoptosis in SKOV3 and primary EOC cells. Consistently, the disruption of miR-137 via CRISPR/Cas9 inhibited apoptosis and upregulated XIAP in A2780 cells. Furthermore, the effect of miR-137 on apoptosis could be rescued by XIAP in SKOV3 cells. In addition, miR-137 expression is inversely correlated with the level of XIAP protein in both ovarian cancer tissues and cell lines.

Conclusions:

Our data suggest that multiple miRNAs can regulate XIAP via its 3′UTR. miR-137 can sensitise ovarian cancer cells to cisplatin-induced apoptosis, providing new insight into overcoming drug resistance in ovarian cancer.

MicroRNAs in glioblastoma multiforme pathogenesis and therapeutics

Glioblastoma multiforme (GBM) is the most common and lethal cancer of the adult brain, remaining incurable with a median survival time of only 15 months. In an effort to identify new targets for GBM diagnostics and therapeutics, recent studies have focused on molecular phenotyping of GBM subtypes. This has resulted in mounting interest in microRNAs (miRNAs) due to their regulatory capacities in both normal development and in pathological conditions such as cancer. miRNAs have a wide range of targets, allowing them to modulate many pathways critical to cancer progression, including proliferation, cell death, metastasis, angiogenesis, and drug resistance. This review explores our current understanding of miRNAs that are differentially modulated and pathologically involved in GBM as well as the current state of miRNA-based therapeutics. As the role of miRNAs in GBM becomes more well understood and novel delivery methods are developed and optimized, miRNA-based therapies could provide a critical step forward in cancer treatment.

MicroRNA-155 promotes apoptosis in SKOV3, A2780, and primary cultured ovarian cancer cells

MicroRNAs (miRNAs) are a large group of small non-coding RNAs that can negatively regulate gene expression at the post-transcriptional level. The deregulation of miRNAs has been associated with tumorigenesis, drug resistance, and prognosis in cancers. Deregulated miR-155 has been reported in numerous cancers; however, its function remains unclear. 4',6-Diamidino-2-phenylindole (DAPI) staining and terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) techniques were used to determine the effects of a miR-155 mimic or inhibitor on the apoptotic ratio of ovarian cancer cells induced by cisplatin. Bioinformatic predictions, the dual-luciferase reporter assay, and western blot analysis were used to detect how miR-155 regulates X-linked inhibitor of apoptosis protein (XIAP). We demonstrated that a miR-155 mimic could decrease the IC50 value of cisplatin in SKOV3 ovarian cancer cells. Subsequently, gain- and loss-of-function analyses with a miR-155 mimic and inhibitor showed that miR-155 sensitizes ovarian cancer cells to cisplatin. Furthermore, the results from the luciferase assays and western blot analysis identified XIAP as the direct target of miR-155. In addition, introducing XIAP cDNA without a three prime untranslated region (3'-UTR) rescued the miR-155 promotion of apoptosis. These results indicate that miR-155 mediates cisplatin-induced apoptosis by targeting XIAP in ovarian cancer cells and that miR-155 could be a potential therapeutic target to increase the efficiency of ovarian cancer interventions.

microRNA-762 promotes breast cancer cell proliferation and invasion by targeting IRF7 expression

OBJECTIVES

miRNAs play crucial roles in human tumourigenesis. This study was performed to measure expression and function of miR-762 in breast cancer.

MATERIALS AND METHODS

Expression of miR-762 in breast tissues and cell lines (SK-BR-3, DA-MB-435s, MCF-7 and MDA-MB-231, HBL-100) was measured by using real-time RT-PCR. We restored expression of miR-762 in MCF-7 cells to measure its functional roles. Luciferase assays were performed to reveal the target gene of miR-762.

RESULTS

Expression of miR-762 was high in both breast cancer cell lines and specimens, and its overexpression increased breast cancer cell proliferation and invasion. Interferon regulatory factor 7 (IRF7) is a direct target of miR-762 and overexpression of miR-762 reduced expression of IRF7. Moreover, IRF7 was repressed, its levels inversely correlated to miR-762 expression. IRF7 rescued miR-762-induced cell invasion and proliferation.

CONCLUSIONS

These results demonstrate that miR-762 tumour effect was achieved by targeting IRF7 in human breast cancer specimens.

The role of miRNAs in cutaneous squamous cell carcinoma

MicroRNAs (miRs) are small, noncoding RNAs that negatively regulate gene expressions at posttranscriptional level. Each miR can control hundreds of gene targets and play important roles in various biological and pathological processes such as hematopoiesis, organogenesis, cell apoptosis and proliferation. Aberrant miR expression contributes to initiation and cell progression of cancers. Accumulating studies have found that miRs play a significant role in cutaneous squamous cell carcinoma (cSCC). Deregulations of miRs may contribute to cSCC carcinogenesis is through acting as oncogenic or tumour suppressive miRs. In this study, we summarized the recent data available on cSCC‐associated miRs. In particular, we will discuss the contribution of miR to the initiation and progression of cSCCs. Although there are many obstacles to be overcome, clinical use of miRs as biomarkers for diagnosis, prediction of prognosis and target for therapies, will be a promising area in the future with more expression and functional role of miRs revealed.

Identification of low miR-105 expression as a novel poor prognostic predictor for human glioma

Glioma is the most common and aggressive brain tumor with poor clinical outcome. Identification and development of new biomarkers could be beneficial for diagnosis and prognosis of glioma patients. Recent studies have showed evidences that dysregulation of microRNAs (miRNAs) is involved in glioma tumorigenesis. Therefore, we attempted to identify specific miRNAs as prognostic and predictive markers for glioma. We statistically compared expression profile of 365 miRNAs between WHO grade IV and grade III gliomas, by qRT-PCR. MiR-105 was identified as a remarkably decreased miRNA in grade IV gliomas compared with grade III gliomas (P=0.012, fold change =0.04). We subsequently examined its expression levels in an independent series of gliomas, and statistically analyzed the associations between miR-105 expression and clinicopathological characteristics and survivals of these glioma patients. MiR-105 showed remarkably decreased expression in gliomas as compared to non-neoplastic brains. And grade IV gliomas had significantly lower miR-105 expression compared with grade III and II gliomas (both P<0.001). Additionally, low miR-105 expression was statistically associated with advanced tumor grade, advanced patient's age and low pre-operative Karnofsky performance score (all P<0.001). Furthermore, patients with low miR-105 expression had significantly poorer survival by Kaplan-Meier method (P<0.001). Multivariate analysis indicated miR-105 as an independent prognostic indicator for glioma patients (P=0.018, risk ratio =4.2). Our results suggested that low expression of miR-105 may correlate with unfavorable clinical outcome and be involved in tumorigenesis and aggressive progression of glioma. And miR-105 may be a novel biomarker in prognostic prediction for glioma.

Downregulation of miR-95-3p inhibits proliferation, and invasion promoting apoptosis of glioma cells by targeting CELF2

Gliomas are the most common and aggressive types of tumors in human brain, of which the prognosis remains dismal because of their biological behavior. The involvement of miRNAs in tumorigenesis of various kinds of cancers drives us to explore new miRNAs related to gliomas. We measured expression level of miR‑95‑3p by qRT-PCR in human glioma and non-neoplasm brain tissues and found that higher level of miR‑95‑3p in glioma tissues of higher grade. Biological functions of miR‑95‑3p on glioma cells were investigated by MTT assay, flow cytometry and transwell assay. We discovered the cell lines transfected with miR‑95‑3p ASO (antisense oligonucleotide) had retarded proliferation and invasion but enhanced apoptosis ability. We searched on-line tool Targetscan and selected CELF (CUGBP- and ETR-3-like family 2) as a putative target. Luciferase reporter was employed to confirm the binding sites in 3'UTR region of CELF2 for miR‑95‑3p. The correlation between expression of CELF2 and miR‑95‑3p was determined by western blotting and qRT-PCR both in cell lines and human samples. Results showed CELF2 was a direct target of miR‑95‑3p and expression levels of CELF2 and miR‑95‑3p were negatively correlated. Finally, CELF2 largely abrogated the effects of miR‑95‑3p on proliferation, invasion and apoptosis of glioma cells in rescue experiments, which verified the role of CELF2 in miR‑95‑3p regulating glioma biological behavior. In conclusion, our data suggest the expression level of miR‑95‑3p is positively related to glioma grade and downregulation of miR‑95‑3p affects proliferation, invasion and apoptosis of glioma cells by targeting CELF2. We identified miR‑95‑3p as a putative therapeutic target and CELF2 as a potential tumor suppressor.

High miR-196a and low miR-367 cooperatively correlate with unfavorable prognosis of high-grade glioma

Identification of microRNAs (miRNAs) could be beneficial for the diagnosis and prognosis of glioma. Therefore, we attempted to identify and develop specific miRNAs as prognostic and predictive markers for glioma patients. We compared the expression profiles of 365 miRNAs between 4 glioblastomas (GBMs, WHO grade IV) and 4 anaplastic astrocytomas (AAs, WHO grade III) using miRNA qPCR Array. MiR-196a (P = 0.004, fold change = 289.86) and miR-367 (P = 0.044, fold change = 0.03) were identified as the most up-regulated and down-regulated miRNAs in GBMs compared with AAs, respectively. We subsequently examined miR-196a and miR-367 expression levels in an independent series of 63 gliomas including 50 GBMs and 13 AAs, as well as 10 non-neoplastic brain tissues, and statistically analyzed the associations between miRNA expression and clinicopathological characteristics and survivals of these glioma patients. MiR-196a and miR-367 showed significant increased and decreased expression in high-grade gliomas relative to non-neoplastic brains, as well as in GBMs versus AAs, respectively. Additionally, high-miR-196a and low-miR-367 expression, alone or in combination, statistically correlated with aggressive clinicopathological features of gliomas. Furthermore, overall survivals of glioma patients with high-miR-196a, low-miR-367 and high-miR-196a/low-miR-367 expression tended to be shorter than the corresponding control groups (all P ≤ 0.001). Moreover, multivariate analysis indicated high-miR-196a/low-miR-367 as an independent prognostic indicator for glioma patients (P = 0.005, risk ratio = 1.8). Our results suggested that both high-miR-196a and low-miR-367 expression may be associated with aggressive progression and unfavorable clinical outcome in glioma patients. And combination of high-miR-196a and low-miR-367 expression may be a novel biomarker in identifying a poor prognosis group of high-grade glioma.

Differential expression and clinical significance of three inflammation-related microRNAs in gangliogliomas

PURPOSE

miR21, miR146, and miR155 represent a trio of microRNAs which has been shown to play a key role in the regulation of immune and inflammatory responses. In the present study, we investigated the differential expression and clinical significance of these three miRNAs in glioneuronal tumors (gangliogliomas, GGs) which are characterized by prominent activation of the innate immune response.

METHODS

The expression levels of miR21, miR146, and miR155 were evaluated using Taqman PCR in 34 GGs, including 15 cases with sufficient amount of perilesional cortex. Their expression was correlated with the tumor features and the clinical history of epilepsy. In addition, in situ hybridization was used to evaluate their cellular distribution in both tumor and peritumoral cortex.

RESULTS

Increased expression of miR146a was observed in both tumor and peritumoral cortex compared to control samples. miR146a was detected in both neuronal and astroglial cells. Tumor and peritumoral miR146a expression was negatively correlated with frequency of seizures and the density of activated microglial cells. Neuronal and astroglial expression was observed for both miR21 and miR155 with increased expression of miR21 within the tumor and miR155 in the peritumoral region. Negative correlations were observed between the miRNA levels and the expression of putative targets within the astroglial component of the tumor.

CONCLUSION

We report a differential regulation of three miRNAs, known to be related to inflammation, in both tumor and peritumoral cortex of patients with GG. Moreover, our findings suggest a functional relationship between miR146a expression and epilepsy, either directly in epileptogenesis or as modulation of seizure activity.

Comprehensive analysis of microRNA expression profile in malignant glioma tissues

Malignant gliomas represent the most devastating group of brain tumors in adults, among which glioblastoma multiforme (GBM) exhibits the highest malignancy rate. Despite combined modality treatment, GBM recurs and is invariably fatal. A further insight into the molecular background of gliomagenesis is required to improve patient outcomes. The primary aim of this study was to gain broad information on the miRNA expression pattern in malignant gliomas, mainly GBM. We investigated the global miRNA profile of malignant glioma tissues with miRNA microarrays, deep sequencing and meta-analysis. We selected miRNAs that were most frequently deregulated in glioblastoma tissues, as well as in peritumoral areas, in comparison with normal human brain. We identified candidate miRNAs associated with the progression from glioma grade III to glioma grade IV. The meta-analysis of miRNA profiling studies in GBM tissues summarizes the past and recent advances in the investigation of the miRNA signature in GBM versus noncancerous human brain and provides a comprehensive overview. We propose a list of 35 miRNAs whose expression is most frequently deregulated in GBM patients and of 30 miRNA candidates recognized as novel GBM biomarkers.

A major role for microRNAs in glioblastoma cancer stem-like cells

Studies have demonstrated that miRNAs contribute to the maintenance and phenotype of in several cancer types. This review will focus on the roles of a few well studied miRNAs in cancer stem-like cells of glioblastoma.

miR-155 contributes to the progression of glioma by enhancing Wnt/β-catenin pathway

As the most common brain tumor, glioma is featured with poor prognosis due to its resistance to current therapeutic strategies. The elucidation of etiology is believed to facilitate the development of novel effective anti-glioma treatment modalities. As a confirmed oncogenic microRNA (miRNA) in many other types of cancers, the role of miR-155 in glioma is still unknown. This study is aimed to study the role of miR-155 in the progression of glioma. Our results revealed that miR-155 was overexpressed in the collected glioma specimen, compared with noncancerous brain tissues. The suppression of miR-155 attenuated the proliferation of glioma cells and the activation of Wnt pathway. Silencing miR-155 was also able to suppress the growth of U-87 MG glioma xenografts in mice. Pearson analysis indicated that miR-155 level was inversely correlated with the abundance of HMG-box transcription factor 1 (HBP1), a strong Wnt pathway inhibitor, in glioma samples. Further experiments confirmed that miR-155 suppressed the expression of HBP1 by targeting the putative miRNA recognition elements (MREs) within its messenger RNA (mRNA) 3' untranslated region (UTR). Furthermore, HBP1 small interfering RNA (siRNA) abolished the effect of miR-155 suppression on the proliferation of glioma and the activation of Wnt pathway. Taken together, miR-155 promoted the progression of glioma by enhancing the activation of Wnt pathway. Thus, targeting miR-155 may be an effective strategy for glioma treatment.

miR-494-3p Regulates Cellular Proliferation, Invasion, Migration, and Apoptosis by PTEN/AKT Signaling in Human Glioblastoma Cells

Malignant gliomas are the most common primary brain tumors, and the molecular mechanisms involving their progression and recurrence are still largely unclear. Substantial data indicate that the oncogene miR-494-3p is significantly elevated in gliomas, but the molecular functions of miR-494-3p in gliomagenesis are largely unknown. The present study aimed to explore the role of miR-494-3p and its molecular mechanism in human brain gliomas, malignant glioma cell lines, and cancer stem-like cells. The expression level of miR-494-3p in 48 human glioma issues and 8 normal brain tissues was determined using stem-loop real-time polymerase chain reaction (PCR). To study the function of miR-494-3p inhibitor in glioma cells, the miR-494-3p inhibitor lentivirus was used to transfect glioma cells. Transwell invasion system was used to estimate the effects of miR-494-3p inhibitor on the invasiveness of glioma cells. A mouse model was used to test the effect of miR-494-3p inhibitor on glioma proliferation and invasion in vivo. Results showed that the expression of miR-494-3p in human brain glioma tissues was higher than in normal brain tissues. Downregulated expression of miR-494-3p can inhibit the invasion and proliferation and promote apoptosis in glioma cells. Quantitative reverse transcription PCR and Western blotting analysis revealed that the expression of PTEN was increased after downexpression of miR-494-3p in glioma cells (U87 and U251). miR-494-3p inhibitor could prevent migration, invasion, proliferation, and promote apotosis in gliomas through PTEN/AKT pathway. Therefore, the study results have shown that miR-494-3p may act as a therapeutic target in gliomas.

PCAF-mediated Akt1 acetylation enhances the proliferation of human glioblastoma cells

Glioblastoma is the most aggressive malignant primary brain tumor in humans. The activation of PI3K/Akt1 signaling pathway is involved in the proliferation of glioblastoma; however, the underlying mechanism of Akt1 activation during the development of glioblastoma remains largely unclear. Recently, the modification of molecular molecules at protein level such as acetylation has been shown to be related to the function of these molecules. Thus, in our present studies, the acetylation of Akt1 molecule and its role in the proliferation of glioblastoma cells was explored. The results showed that Akt1 was markedly acetylated in glioblastoma cells compared to normal human astrocytes. Mechanistically, PCAF-mediated Akt1 acetylation enhanced Akt1 phosphorylation at both sites of Thr(308) and Ser(473) and further promoted the proliferation of glioblastoma cells. Together, these data implicate that, as a post-translational regulation, PCAF-mediated Akt1 acetylation plays an important role in the proliferation of human glioblastoma, suggesting a novel target for clinical application.

Risk Score based on microRNA expression signature is independent prognostic classifier of glioblastoma patients

Glioblastoma multiforme (GBM) is the most malignant primary brain tumor. The prognosis of GBM patients varies considerably and the histopathological examination is not sufficient for individual risk estimation. MicroRNAs (miRNAs) are small, non-coding RNAs that function as post-transcriptional regulators of gene expression and were repeatedly proved to play important roles in pathogenesis of GBM. In our study, we performed global miRNA expression profiling of 58 glioblastoma tissue samples obtained during surgical resections and 10 non-tumor brain tissues. The subsequent analysis revealed 28 significantly deregulated miRNAs in GBM tissue, which were able to precisely classify all examined samples. Correlation with clinical data led to identification of six-miRNA signature significantly associated with progression free survival [hazard ratio (HR) 1.98, 95% confidence interval (CI) 1.33-2.94, P < 0.001] and overa+ll survival (HR 2.86, 95% CI 1.91-4.29, P < 0.001). O(6)-methylguanine-DNA methyltransferase methylation status was evaluated as reference method and Risk Score based on six-miRNA signature indicated significant superiority in prediction of clinical outcome in GBM patients. Multivariate Cox analysis indicated that the Risk Score based on six-miRNA signature is an independent prognostic classifier of GBM patients. We suggest that the Risk Score presents promising prognostic algorithm with potential for individualized treatment decisions in clinical management of GBM patients.

MicroRNA-188 suppresses G1/S transition by targeting multiple cyclin/CDK complexes

BACKGROUND

Accelerated cell cycle progression is the common feature of most cancers. MiRNAs can act as oncogenes or tumor suppressors by directly modulating cell cycle machinery. It has been shown that miR-188 is upregulated in UVB-irradiated mouse skin and human nasopharyngeal carcinoma CNE cells under hypoxic stress. However, little is known about the function of miR-188 in cell proliferation and growth control.

RESULTS

Overexpression of miR-188 inhibits cell proliferation, tumor colony formation and G1/S cell cycle transition in human nasopharyngeal carcinoma CNE cells. Using bioinformatics approach, we identify a series of genes regulating G1/S transition as putative miR-188 targets. MiR-188 inhibits both mRNA and protein expression of CCND1, CCND3, CCNE1, CCNA2, CDK4 and CDK2, suppresses Rb phosphorylation and downregulates E2F transcriptional activity. The expression level of miR-188 also inversely correlates with the expression of miR-188 targets in human nasopharyngeal carcinoma (NPC) tissues. Moreover, studies in xenograft mouse model reveal that miR-188 is capable of inhibiting tumor initiation and progression by suppressing target genes expression and Rb phosphorylation.

CONCLUSIONS

This study demonstrates that miR-188 exerts anticancer effects, via downregulation of multiple G1/S related cyclin/CDKs and Rb/E2F signaling pathway.

MicroRNA-363-mediated downregulation of S1PR1 suppresses the proliferation of hepatocellular carcinoma cells

S1PR1 plays a crucial role in promoting proliferation of hepatocellular carcinoma (HCC). Over expression of S1PR1 is observed in HCC cell lines. The mechanisms underlying the aberrant expression of S1PR1 are not known well. MircroRNAs are important regulators of gene expression and disproportionate microRNAs can result in dysregulation of oncogenes in cancer cells. In this study, we found that miR-363, a potential tumor suppressor microRNA, downregulated the expression of S1PR1 and inhibited the proliferation of HCC cells. Bioinformatic analysis predicted a putative binding site of miR-363 within the 3'-UTR of S1PR1 mRNA. Luciferase reporter assay showed that miR-363 directly targeted the 3'-UTR of S1PR1 mRNA. Transfection of miR-363 mimics suppressed S1PR1 expression in HCC cells, followed by the repression of the activation of ERK and STAT3. Moreover, we found that the expression of downstream genes of ERK and STAT3, including PDGF-A, PDGF-B, MCL-1 and Bcl-xL, was suppressed after miR-363 transfection. Taken together, the present study demonstrated that miR-363 was a negative regulator of S1PR1 expression in HCC cells and inhibited cell proliferation, suggesting that the miR-363/S1PR1 pathway might be a novel target for the treatment of HCC.