miR-106b is overexpressed in medulloblastomas and interacts directly with PTEN

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.

Regulatory networks and 5' partner usage of miRNA host gene fusions in breast cancer

Genomic rearrangements in cancer cells can create gene fusions where the juxtaposition of two different genes leads to the production of chimeric proteins or altered gene expression through promoter‐swapping. We have previously shown that fusion transcripts involving microRNA (miRNA) host genes contribute to deregulation of miRNA expression regardless of the protein‐coding potential of these transcripts. Many different genes can also be used as 5′ partners by a miRNA host gene in what we named recurrent miRNA‐convergent fusions. Here, we have explored the properties of 5′ partners in fusion transcripts that involve miRNA hosts in breast tumours from The Cancer Genome Atlas (TCGA). We hypothesised that firstly, 5′ partner genes should belong to pathways and transcriptional programmes that reflect the tumour phenotype and secondly, there should be a selection for fusion events that shape miRNA expression to benefit the tumour cell through the known hallmarks of cancer. We found that the set of 5′ partners in miRNA host fusions is non‐random, with overrepresentation of highly expressed genes in pathways active in cancer including epithelial‐to‐mesenchymal transition, translational regulation and oestrogen signalling. Furthermore, many miRNAs were upregulated in samples with host gene fusions, including established oncogenic miRNAs such as mir‐21 and the mir‐106b~mir‐93~mir‐25 cluster. To the list of mechanisms for deregulation of miRNA expression, we have added fusion transcripts that change the promoter region. We propose that this adds material for genetic selection and tumour evolution in cancer cells and that miRNA host fusions can act as tumour ‘drivers’.

Spectrum of microRNAs and their target genes in cancer: intervention in diagnosis and therapy

Till date, several groups have studied the mechanism of microRNA (miRNA) biogenesis, processing, stability, silencing, and their dysregulation in cancer. The miRNA coding genes recurrently go through abnormal amplification, deletion, transcription, and epigenetic regulation in cancer. Some miRNAs function as tumor promoters while few others are tumor suppressors based on the transcriptional regulation of target genes. A review of miRNAs and their target genes in a wide range of cancers is attempted in this article, which may help in the development of new diagnostic tools and intervention therapies. The contribution of miRNAs for drug sensitivity or resistance in cancer therapy and opportunities of miRNAs in cancer prognosis or diagnosis and therapy is also presented in detail.

Role of MicroRNAs in the Development and Progression of the Four Medulloblastoma Subgroups

Medulloblastoma is the most frequent malignant brain tumour in children. Medulloblastoma originate during the embryonic stage. They are located in the cerebellum, which is the area of the central nervous system (CNS) responsible for controlling equilibrium and coordination of movements. In 2012, medulloblastoma were divided into four subgroups based on a genome-wide analysis of RNA expression. These subgroups are named Wingless, Sonic Hedgehog, Group 3 and Group 4. Each subgroup has a different cell of origin, prognosis, and response to therapies. Wingless and Sonic Hedgehog medulloblastoma are so named based on the main mutation originating these tumours. Group 3 and Group 4 have generic names because we do not know the key mutation driving these tumours. Gene expression at the post-transcriptional level is regulated by a group of small single-stranded non-coding RNAs. These microRNA (miRNAs or miRs) play a central role in several cellular functions such as cell differentiation and, therefore, any malfunction in this regulatory system leads to a variety of disorders such as cancer. The role of miRNAs in medulloblastoma is still a topic of intense clinical research; previous studies have mostly concentrated on the clinical entity of the single disease rather than in the four molecular subgroups. In this review, we summarize the latest discoveries on miRNAs in the four medulloblastoma subgroups.

Noncoding RNAs in pediatric brain tumors: Molecular functions and pathological implications

Brain tumors are common solid pediatric malignancies and the main reason for cancer-related death in the pediatric setting. Recently, evidence has revealed that noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), play a critical role in brain tumor development and progression. Therefore, in this review article, we describe the functions and molecular mechanisms of ncRNAs in multiple types of cancer, including medulloblastoma, pilocytic astrocytoma, ependymoma, atypical teratoid/rhabdoid tumor, glioblastoma, diffuse intrinsic pontine glioma, and craniopharyngioma. We also mention the limitations of using ncRNAs as therapeutic targets because of the nonspecificity of ncRNA targets and the delivery methods of ncRNAs. Due to the critical role of ncRNAs in brain oncogenesis, targeting aberrantly expressed ncRNAs might be an effective strategy to improve the outcomes of pediatric patients with brain tumors.

The Role of MicroRNAs in Therapeutic Resistance of Malignant Primary Brain Tumors

Brain tumors in children and adults are challenging tumors to treat. Malignant primary brain tumors (MPBTs) such as glioblastoma have very poor outcomes, emphasizing the need to better understand their pathogenesis. Developing novel strategies to slow down or even stop the growth of brain tumors remains one of the major clinical challenges. Modern treatment strategies for MPBTs are based on open surgery, chemotherapy, and radiation therapy. However, none of these treatments, alone or in combination, are considered effective in controlling tumor progression. MicroRNAs (miRNAs) are 18-22 nucleotide long endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level by interacting with 3'-untranslated regions (3'-UTR) of mRNA-targets. It has been proven that miRNAs play a significant role in various biological processes, including the cell cycle, apoptosis, proliferation, differentiation, etc. Over the last decade, there has been an emergence of a large number of studies devoted to the role of miRNAs in the oncogenesis of brain tumors and the development of resistance to radio- and chemotherapy. Wherein, among the variety of molecules secreted by tumor cells into the external environment, extracellular vesicles (EVs) (exosomes and microvesicles) play a special role. Various elements were found in the EVs, including miRNAs, which can be transported as part of these EVs both between neighboring cells and between remotely located cells of different tissues using biological fluids. Some of these miRNAs in EVs can contribute to the development of resistance to radio- and chemotherapy in MPBTs, including multidrug resistance (MDR). This comprehensive review examines the role of miRNAs in the resistance of MPBTs (e.g., high-grade meningiomas, medulloblastoma (MB), pituitary adenomas (PAs) with aggressive behavior, and glioblastoma) to chemoradiotherapy and pharmacological treatment. It is believed that miRNAs are future therapeutic targets in MPBTs and such the role of miRNAs needs to be critically evaluated to focus on solving the problems of resistance to therapy this kind of human tumors.

microRNAs in liver and kidney ischemia reperfusion injury: insight to improve transplantation outcome

Ischemia reperfusion injury (IRI) is a condition that occurs wherever blood flow and oxygen is reduced or absent, such as trauma, vascular disease, stroke, and solid organ transplantation. This condition can lead to tissue damage, especially during organ transplantation. Under such circumstances, some signaling pathways are activated, leading to up- or down- regulation of several genes such as microRNAs (miRNAs) that might attenuate or ameliorate this status. Therefore, by manipulating miRNAs level, they can be used as a biomarker for early diagnosis of IRI or suggestive to be therapeutic agents in clinical situation in future.

The Non-coding Side of Medulloblastoma

Medulloblastoma (MB) is the most common pediatric brain tumor and a primary cause of cancer-related death in children. Until a few years ago, only clinical and histological features were exploited for MB pathological classification and outcome prognosis. In the past decade, the advancement of high-throughput molecular analyses that integrate genetic, epigenetic, and expression data, together with the availability of increasing wealth of patient samples, revealed the existence of four molecularly distinct MB subgroups. Their further classification into 12 subtypes not only reduced the well-characterized intertumoral heterogeneity, but also provided new opportunities for the design of targets for precision oncology. Moreover, the identification of tumorigenic and self-renewing subpopulations of cancer stem cells in MB has increased our knowledge of its biology. Despite these advancements, the origin of MB is still debated, and its molecular bases are poorly characterized. A major goal in the field is to identify the key genes that drive tumor growth and the mechanisms through which they are able to promote tumorigenesis. So far, only protein-coding genes acting as oncogenic drivers have been characterized in each MB subgroup. The contribution of the non-coding side of the genome, which produces a plethora of transcripts that control fundamental biological processes, as the cell choice between proliferation and differentiation, is still unappreciated. This review wants to fill this major gap by summarizing the recent findings on the impact of non-coding RNAs in MB initiation and progression. Furthermore, their potential role as specific MB biomarkers and novel therapeutic targets is also highlighted.

miR-196B-5P and miR-200B-3P Are Differentially Expressed in Medulloblastomas of Adults and Children

Medulloblastoma is a highly aggressive brain tumor that typically affects children, while in adults it represents ~1% of all brain tumors. Little is known about microRNA expression profile of the rare adult medulloblastoma. The main aim of this study was to identify peculiar differences in microRNA expression between childhood and adult medulloblastoma. Medulloblastomas were profiled for microRNA expression using the Exiqon Human miRNome panel (I + II) analyzing 752 microRNAs in a training set of six adult and six childhood cases. Then, the most differentially expressed microRNAs were validated in a total of 21 adult and 19 childhood cases. Eight microRNAs (miR-196b-5p, miR-183-5p, miR-200b-3p, miR-196a-5p, miR-193a-3p, miR-29c-3p, miR-33b-5p, and miR-200a-3p) were differentially expressed in medulloblastoma of adults and children. Analysis of the validation set confirmed that miR-196b-5p and miR-200b-3p were significantly overexpressed in medulloblastoma of adults as compared with those of children. We followed an in silico approach to investigate direct targets and the pathways involved for the two microRNAs (miR-196b and miR-200b) differently expressed between adult and childhood medulloblastoma. Adult and childhood medulloblastoma have different miRNA expression profiles. In particular, the differential dysregulation of miR-196b-5p and miR-200b-3p characterizes the miRNA profile of adult medulloblastoma and suggests potential targets for novel diagnostic, prognostic, or therapeutic strategies.

Aberrantly expressed microRNAs and their implications in childhood central nervous system tumors

Even though the treatment of childhood cancer has evolved significantly in recent decades, aggressive central nervous system (CNS) tumors are still a leading cause of morbidity and mortality in this population. Consequently, the identification of molecular targets that can be incorporated into diagnostic practice, effectively predict prognosis, follow treatment response, and materialize into potential targeted therapeutic approaches are still warranted. Since the first evidence of the participation of miRNAs in cancer development and progression 20 years ago, notable progress has been made in the basic understanding of the contribution of their dysregulation as epigenetic driver of tumorigenesis. Nevertheless, among the plethora of articles in the literature, microRNA profiling of pediatric tumors are scarce. This article gives an overview of the recent advances in the diagnostic/prognostic potential of miRNAs in a selection of pediatric CNS tumors: medulloblastoma, ependymoma, pilocytic astrocytoma, glioblastoma, diffuse intrinsic pontine glioma, atypical teratoid/rhabdoid tumors, and choroid plexus tumors.

The therapeutic and diagnostic potential of regulatory noncoding RNAs in medulloblastoma

Medulloblastoma, a central nervous system tumor that predominantly affects children, always requires aggressive therapy. Nevertheless, it frequently recurs as resistant disease and is associated with high morbidity and mortality. While recent efforts to subclassify medulloblastoma based on molecular features have advanced our basic understanding of medulloblastoma pathogenesis, optimal targets to increase therapeutic efficacy and reduce side effects remain largely undefined. Noncoding RNAs (ncRNAs) with known regulatory roles, particularly long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), are now known to participate in medulloblastoma biology, although their functional significance remains obscure in many cases. Here we review the literature on regulatory ncRNAs in medulloblastoma. In providing a comprehensive overview of ncRNA studies, we highlight how different lncRNAs and miRNAs have oncogenic or tumor suppressive roles in medulloblastoma. These ncRNAs possess subgroup specificity that can be exploited to personalize therapy by acting as theranostic targets. Several of the already identified ncRNAs appear specific to medulloblastoma stem cells, the most difficult-to-treat component of the tumor that drives metastasis and acquired resistance, thereby providing opportunities for therapy in relapsing, disseminating, and therapy-resistant disease. Delivering ncRNAs to tumors remains challenging, but this limitation is gradually being overcome through the use of advanced technologies such as nanotechnology and rational biomaterial design.

MicroRNA-106b serves as a prognostic biomarker and is associated with cell proliferation, migration, and invasion in osteosarcoma

MicroRNAs (miRNAs) have been demonstrated to be involved in tumor progression of various human malignancies. The purpose of this study was to investigate the expression patterns and prognostic value of microRNA-106b (miR-106b) in osteosarcoma (OS) and to examine its functional role in OS progression. Reverse transcription-quantitative PCR (RT-qPCR) was used to estimate the expression of miR-106b in OS tissues and cells. The prognostic value of miR-106b in OS was evaluated by plotting Kaplan-Meier survival curves and performing Cox analyses. Cell experiments were carried out to examine the effects of miR-106b on OS cell proliferation, migration, and invasion. The expression of miR-106b was elevated in both OS tissues and cells compared with the expression in normal control tissues and cells (P<0.001). miR-106b expression was associated with metastasis (P=0.028) and Tumor-Node-Metastasis stage (P=0.017). Patients with high miR-106b expression levels had a poorer overall survival rate compared with those with low miR-106b expression levels (log-rank P=0.001). Multivariate Cox analyses indicated that miR-106b expression was an independent prognostic factor for patients with OS (hazard ratio=2.769; 95% confidence interval=1.369-5.599; P=0.005). The results of cell experiments implied that the upregulation of miR-106b could promote OS cell proliferation, migration and invasion, whereas the downregulation of miR-106b could suppress these functions (P<0.05). Taken together, this study's results indicated that the overexpression of miR-106b is associated with a poor prognosis for patients with OS and that overexpression promotes OS cell proliferation, migration, and invasion. This study may provide a novel prognostic biomarker and a candidate therapeutic target for OS treatment.

MicroRNA-32 targeting PTEN enhances M2 macrophage polarization in the glioma microenvironment and further promotes the progression of glioma

This study was aimed to explore the molecular mechanism of macrophage polarization and its effect on glioma progression. THP1 cells were cocultured in conditioned medium from U87 human glioblastoma cells to simulate the glioma microenvironment. The expression of miR-32 and PTEN in THP1 cells was detected by real-time PCR. A luciferase reporter assay was conducted to confirm the target relation between miR-32 and PTEN. Western blot assays and ELISA were performed to detect PTEN, M2 macrophage-specific markers, PI3K/AKT signaling proteins, and apoptosis-related proteins. U87 cell proliferation was evaluated by CCK-8 and colony forming assays, and the migration ability of the cells was evaluated by Transwell and wound healing assays. The U87 culture supernatant promoted the M2 phenotype of THP1 cells. miR-32 was upregulated and PTEN was downregulated in THP1 cells with the M2 phenotype in the glioma microenvironment. Luciferase assays confirmed that PTEN expression was suppressed by miR-32 through interaction with the 3'UTR of PTEN. Overexpression of miR-32 suppressed PTEN expression in THP1 cells. Overexpression of miR-32 or downregulation of PTEN promoted the expression of M2 macrophage-specific markers, thereby enhancing M2 macrophage polarization. Additionally, miR-32 inhibited THP1 cell apoptosis via suppressing the PI3K/AKT signaling pathway. Most importantly, the proliferation and migration capacities of U87 cells treated with the THP1 culture supernatant after miR-32 overexpression were enhanced, and these effects could be reversed by cotransfection with pcDNA3.1-PTEN. miR-32 negatively modulates PTEN, thereby promoting M2 macrophage transformation through PI3K/AKT signaling, enhancing glioma proliferation and migration abilities.

miR miR on the wall, who's the most malignant medulloblastoma miR of them all?

microRNAs (miRNAs) have wide-ranging effects on large-scale gene regulation. As such, they play a vital role in dictating normal development, and their aberrant expression has been implicated in cancer. There has been a large body of research on the role of miRNAs in medulloblastoma, the most common malignant brain tumor of childhood. The identification of the 4 molecular subgroups with distinct biological, genetic, and transcriptional features has revolutionized the field of medulloblastoma research over the past 5 years. Despite this, the growing body of research on miRNAs in medulloblastoma has largely focused on the clinical entity of a single disease rather than the molecular subgroups. This review begins by highlighting the role of miRNAs in development and progresses to explore their myriad of implications in cancer. Medulloblastoma is characterized by increased proliferation, inhibition of apoptosis, and maintenance of stemness programs-features that are inadvertently regulated by altered expression patterns in miRNAs. This review aims to contextualize the large body of work on miRNAs within the framework of medulloblastoma subgroups. The goal of this review is to stimulate new areas of research, including potential therapeutics, within a rapidly growing field.

Role of GLI Transcription Factors in Pathogenesis and Their Potential as New Therapeutic Targets

GLI transcription factors have important roles in intracellular signaling cascade, acting as the main mediators of the HH-GLI signaling pathway. This is one of the major developmental pathways, regulated both canonically and non-canonically. Deregulation of the pathway during development leads to a number of developmental malformations, depending on the deregulated pathway component. The HH-GLI pathway is mostly inactive in the adult organism but retains its function in stem cells. Aberrant activation in adult cells leads to carcinogenesis through overactivation of several tightly regulated cellular processes such as proliferation, angiogenesis, EMT. Targeting GLI transcription factors has recently become a major focus of potential therapeutic protocols.

The emerging roles of the polycistronic miR-106b∼25 cluster in cancer - A comprehensive review

MicroRNAs (miRNAs) are short, non-coding RNA molecules that regulate gene expression at the post-transcriptional level by inhibiting translation and decreasing the stability of the targeted transcripts. Over the last two decades, miRNAs have been recognized as important regulators of cancer cell biology, acting either as oncogenes or tumor suppressors. The polycistronic miR-106b∼25 cluster, located within an intron of MCM7 gene, consists of three highly conserved miRNAs: miR-25, miR-93 and miR-106b. A constantly growing body of evidence indicates that these miRNAs are overexpressed in numerous human malignancies and regulate multiple cellular processes associated with cancer development and progression, including: cell proliferation and survival, invasion, metastasis, angiogenesis and immune evasion. Furthermore, recent studies revealed that miR-106b∼25 cluster miRNAs modulate cancer stem cells characteristics and might promote resistance to anticancer therapies. In light of these novel discoveries, miRNAs belonging to the miR-106b∼25 cluster have emerged as key oncogenic drivers as well as potential biomarkers and plausible therapeutic targets in different tumor types. Herein, we comprehensively review novel findings on the roles of miR-106b∼25 cluster in human cancer, and provide a broad insight into the molecular mechanisms underlying its oncogenic properties.

Identification of microRNA signature in different pediatric brain tumors

Understanding pediatric brain tumor biology is essential to help on disease stratification, and to find novel markers for early diagnosis. MicroRNA (miRNA) expression has been linked to clinical outcomes and tumor biology. Here, we aimed to detect the expression of different miRNAs in different pediatric brain tumor subtypes to discover biomarkers for early detection and develop novel therapies. Expression of 82 miRNAs was detected in 120 pediatric brain tumors from fixed-formalin paraffin-embedded tissues, low-grade glioma, high-grade glioma, ependymoma, and medulloblastoma, using quantitative real-time PCR. Low-expression of miR-221, miR-9, and miR-181c/d and over-expression of miR-101, miR-222, miR-139, miR-1827, and miR-34c was found in medulloblastoma; low expression of miR-10a and over-expression of miR-10b and miR-29a in ependymoma; low expression of miR-26a and overexpression of miR-19a/b, miR-24, miR-27a, miR- 584, and miR-527 in low-grade glioma. Cox regression showed differential miRNA expression between responders and non-responders. The most specific were miR-10a and miR-29a low expression in LGG non-responders, miR-135a and miR-146b over-expression in ependymoma non-responders, and miR-135b overexpression in medulloblastoma non-responders. MicroRNAs are differentially expressed in subtypes of brain tumors suggesting that they may help diagnosis. A greater understanding of aberrant miRNA in pediatric brain tumors may support development of novel therapies.

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.

Exosomes derived from pancreatic cancer cells induce insulin resistance in C2C12 myotube cells through the PI3K/Akt/FoxO1 pathway

Prospective epidemiological studies have consistently suggested that pancreatic cancer-associated new-onset diabetes mellitus (PC-DM) represents a potential platform for early diagnose of pancreatic cancer (PC). Despite the studies performed, the mechanism behind this phenomenon remains ambiguous. In this study, we explored the effects of two types of exosomes released by murine pancreatic cancer and ductal epithelial cells on murine skeletal muscle cells. The results show that PC-derived exosomes can readily enter C2C12 myotubes, triggering lipidosis and glucose intake inhibition. We also demonstrate that PC-derived exosomes can inhibit insulin and PI3K/Akt signalling, in which insulin-induced FoxO1 nuclear exclusion is preserved and Glut4 trafficking is impaired. Microarray and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses show that exosomal microRNAs (miRNAs) probably play key roles in this process, an assumption that is corroborated by in vitro studies. These results confirm that the insulin resistance (IR) of skeletal muscle cells is governed by PC-derived exosomes through the insulin and PI3K/Akt/FoxO1 signalling pathways, where exosomal miRNAs potentially contribute to this phenomenon. These novel findings pave the way towards a comprehensive understanding of the cancer theories: "metabolic reprogramming" and "metabolic crosstalk".

Effect of miR-106b on Invasiveness of Pituitary Adenoma via PTEN-PI3K/AKT

Background

Pituitary adenomas are mostly benign tumors, although certain cases have invasiveness, which might be related with high expression of miR-106b. The PTEN-PI3K/AKT signal pathway is known to be related with cell migration and invasion. Among these, PTEN is the target gene for miR-106b. Whether miR-106b affects invasiveness of pituitary adenoma via PTEN-PI3K/AKT is unclear.

Material/Methods

Both invasive and non-invasive pituitary adenoma tissue samples were collected from our Neurosurgery Department, in parallel with brain tissues after head contusion surgery. Pituitary adenoma cell line HP75 was cultured in vitro and divided into NC and miR-106b inhibitor groups for measuring cell cycle/proliferation. Malignant growth of cells was measured by agarose gel clonal assay, while cell migration and invasion were reflected by starch assay and Transwell assay, respectively. The expression of PTEN, PI3K/AKT, and MMP-9 was measured.

Results

MiR-106b was significantly up-regulated in pituitary adenoma but PTEN was down-regulated, especially in invasive tumors. The inhibition of miR-106b remarkably suppressed proliferation and anchorage-independent growth of HP75 cells, with major arrest of cell cycles. The inhibition of miR-106b significantly depressed starch healing and invasive potency of cells. A negative targeted regulation existed between miR-106b and PTEN, as the inhibition of miR-106b significantly enhanced PTEN expression, affecting the activity of downstream PI3K/AKT signaling pathway, thus affecting migration and invasion of pituitary adenoma.

Conclusions

MiR-106b can affect migration and invasion of pituitary adenoma cells via regulating PTEN and further activity of the PI3K/AKT signaling pathway and MMP-9 expression.

MiR-106b promotes migration and invasion through enhancing EMT via downregulation of Smad 7 in Kazakh's esophageal squamous cell carcinoma

Accumulated evidence suggests that miR-106b played a key role in the promotion of the metastases of cancer; however, little is known about miR-106b in esophageal squamous cell carcinoma (ESCC). To investigate expression level of miR-106b in ESCC tissues, quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect miR-106b expression in 35 Kazakh's ESCC and paired normal adjacent tissues (NATs). To evaluate the role mediated by miR-106b in the proliferation, migration, and invasion, MTT, wound healing, and transwell assays were employed, respectively. Luciferase reporter assay was used to identify the downstream target through miR-106b. To understand the regulation between miR-106b and Smad 7, qRT-PCR and western blot were performed. The present study showed that miR-106b was pronouncedly upregulated in ESCC relative to paired NAT and that upregulated miR-106b was significantly associated with lymph node metastases. MiR-106b was found to be able to promote proliferation, migration, and invasion of ESCC cells in vitro. Smad 7 was confirmed as a downstream target of miR-106b in our experimental setting. Smad 7 was remarkably downregulated in ESCC compared with paired NAT. In addition, upregulation of miR-106b can promote epithelial mesenchymal transition (EMT) in ESCC cell in vitro. Our results indicated that miR-106b can promote migration and invasion of ESCC cells through enhancing EMT process via downregulation of Smad 7, suggesting that miR-106b can be a potential molecular phenotype in ESCC metastases.

Elevated serum miR-106b and miR-146a in patients with focal and generalized epilepsy

BACKGROUND

Epilepsy is a chronic neurological disorder characterized by recurring seizures. Although scalp electroencephalograms (EEG) and neuroimaging have been used in clinical diagnosis of epilepsy, the more economical, rapid and non-invasive biomarker is still desirable, contributing to the accurate clinical diagnosis and facilitating the appropriate treatment.

METHODS

The expression of four epilepsy-associated miRNAs (miR-106b, miR-146a, miR-194-5p and miR-301a) was measured by quantitative RT-PCR in the serum of 90 epilepsy patients and control populations.

RESULTS

It was found that the serum miR-106b, miR-146a and miR-301a were significantly increased but serum miR-194-5p was significantly decreased in epilepsy patients compared with healthy control populations. In addition, serum miR-106b (r=0.6412) and miR-146a (r=0.5896) were correlated with NHS3 score in epilepsy patients. Furthermore, the ROC result of serum miR-106b for prediction of epilepsy was 0.786, higher than those of serum miR-146a (AUC=0.774), miR-194 (AUC=0.686) or miR-310a (AUC=0.696). The combination of serum miR-106b and miR-146a gained a better sensitivity/specificity for prediction of epilepsy (AUC=0.887).

CONCLUSION

Our preliminary findings indicate that upregulated serum miR-106b and miR-146a might be a potential biomarker for epilepsy evaluation.

MicroRNA and gene co-expression networks characterize biological and clinical behavior of rhabdomyosarcomas

Rhabdomyosarcomas (RMS) in children and adolescents are heterogeneous sarcomas broadly defined by skeletal muscle features and the presence/absence of PAX3/7-FOXO1 fusion genes. MicroRNAs are small non-coding RNAs that regulate gene expression in a cell context specific manner. Sequencing analyses of microRNAs in 64 RMS revealed expression patterns separating skeletal muscle, fusion gene positive and negative RMS. Integration with parallel gene expression data assigned biological functions to 12 co-expression networks/modules that reassuringly included myogenic roles strongly correlated with microRNAs known in myogenesis and RMS development. Modules also correlated with clinical outcome and fusion status. Regulation of microRNAs by the fusion protein was demonstrated after PAX3-FOXO1 reduction, exemplified by miR-9-5p. MiR-9-5p levels correlated with poor outcome, even within fusion gene positive RMS, and were higher in metastatic versus non-metastatic disease. MiR-9-5p reduction inhibited RMS cell migration. Our findings reveal microRNAs in a regulatory framework of biological and clinical significance in RMS.

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RNAseq profiled miRNA expression in 64 rhabdomyosarcomas (RMS).

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MiRNA expression distinguished muscle and RMS on the basis of fusion gene status.

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Co-expression networks linked to function, clinical data and fusion gene status.

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Identified miRNAs, including miR-9-5p, altered by the PAX3-FOXO1 fusion protein.

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Demonstrated clinical and functional role for miR-9-5p in RMS.

MicroRNA-106b promotes pituitary tumor cell proliferation and invasion through PI3K/AKT signaling pathway by targeting PTEN

The purpose of this study was to investigate the expression of microRNA-106b (miR-106b) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in pituitary tumor and to confirm whether miR-106b promotes proliferation and invasion of pituitary tumor cells through the PI3K/AKT signaling pathway by targeted regulation of PTEN expression, and thereby to find new targets for the treatment of pituitary tumor. Fifty-five cases of pituitary tumor tissue samples were collected, including 29 cases of invasive pituitary tumor, non-invasive 26 cases, and 8 normal pituitaries. The expression level of miR-106b in pituitary tumor tissue was detected by quantitative real-time PCR, and the expression of PTEN protein was detected by immunohistochemistry. PTEN 3'-untranslated region (UTR) luciferase vector was constructed, and dual-luciferase reporter gene assay was employed to examine the effect of miR-106b on PTEN 3'-UTR luciferase activity. AtT-20 cells were transfected with miR-106b mimics, miR-106b inhibitor, PTEN expression plasmid, and miR-106b mimics + PTEN expression plasmid respectively, and the changes in cellular proliferation and invasion were observed via MTT method and transwell assay respectively. PTEN messenger RNA (mRNA) expression was determined by quantitative real-time PCR, and western blotting was performed to detect the expression of PTEN, PI3K, AKT, and pAKT. miR-106b showed up-regulation in invasive pituitary tumor tissue: the expression level was significantly up-regulated compared with normal tissues and the non-invasive pituitary tumor tissue (P < 0.05). The positive rate of PTEN protein expression in invasive pituitary tumor tissues was significantly lower than in normal and non-invasive tissues (P < 0.01). Dual-luciferase reporter gene assay showed that miR-106b could bind to the 3'-UTR of PTEN specifically and significantly inhibited the luciferase activity, cutting the 46 % (P < 0.01). Down-regulation of miR-106b or up-regulation of PTEN could suppress cell proliferation and invasion of AtT-20 cells, and PTEN expression plasmid could partially simulate the function of miR-106b. Expression of PTEN mRNA and protein decreased significantly in AtT-20 cells overexpressing miR-106b. The expression levels of PI3K and p-AKT were significantly inhibited by miR-106b inhibitor and increased by miR-106b mimics. The expression of miR-106b showed up-regulation in pituitary tumor tissues, while the protein expression of PTEN presented opposite results. The findings of this study further demonstrated that miR-106b as an oncogene regulated the pituitary tumor cell proliferation and invasion in vitro by directly targeting PTEN through the PI3K/AKT signaling pathway. Our study suggests that miR-106b and PTEN are likely to serve as potential diagnostic biomarkers or therapeutic targets for pituitary tumor treatment in the future.

Sox2: regulation of expression and contribution to brain tumors

Tumors of the CNS are composed of a complex mixture of neoplastic cells, in addition to vascular, inflammatory and stromal components. Similar to most other tumors, brain tumors contain a heterogeneous population of cells that are found at different stages of differentiation. The cancer stem cell hypothesis suggests that all tumors are composed of subpopulation of cells with stem-like properties, which are capable of self-renewal, display resistance to therapy and lead to tumor recurrence. One of the most important transcription factors that regulate cancer stem cell properties is SOX2. In this review, we focus on SOX2 and the complex network of signaling molecules and transcription factors that regulate its expression and function in brain tumor initiating cells. We also highlight important findings in the literature about the role of SOX2 in glioblastoma and medulloblastoma, where it has been more extensively studied.

MicroRNA: a connecting road between apoptosis and cholesterol metabolism

Resistance to apoptosis leads to tumorigenesis and failure of anti-cancer therapy. Recent studies also highlight abrogated lipid/cholesterol metabolism as one of the root causes of cancer that can lead to metastatic transformations. Cancer cells are dependent on tremendous supply of cellular cholesterol for the formation of new membranes and continuation of cell signaling. Cholesterol homeostasis network tightly regulates this metabolic need of cancer cells on cholesterol and other lipids. Genetic landscape is also shared between apoptosis and cholesterol metabolism. MicroRNAs (miRNAs) are the new fine tuners of signaling pathways and cellular processes and are known for their ability to post-transcriptionally repress gene expression in a targeted manner. This review summarizes the current knowledge about the cross talk between apoptosis and cholesterol metabolism via miRNAs. In addition, we also emphasize herein recent therapeutic modulations of specific miRNAs and their promising potential for the treatment of deadly diseases including cancer and cholesterol related pathologies. Understanding of the impact of miRNA-based regulation of apoptosis and metabolic processes is still at its dawn and needs further research for the development of future miRNA-based therapies. As both these physiological processes affect cellular homeostasis, we believe that this comprehensive summary of miRNAs modulating both apoptosis and cholesterol metabolism will open uncharted territory for scientific exploration and will provide the foundation for discovering novel drug targets for cancer and metabolic diseases.

Dysregulation of renal microRNA expression after deep hypothermic circulatory arrest in rats

OBJECTIVES

Acute kidney injury (AKI) is a severe complication of cardiopulmonary bypass-deep hypothermic circulatory arrest (DHCA) surgery. Non-coding microRNAs (miRNAs) are considered as key players in kidney physiology and pathology. However, whether they are implicated in DHCA-induced AKI at the early stage post-surgery is less studied, and requires for further investigation.

METHODS

In this study, kidney tissues were removed at 2 h post-surgery from Sprague-Dawley rats that underwent a 60-min DHCA (18°C), with samples from sham-operated rats as control. Renal RNA isolates were analysed with Affymetrix miRNA microarray 4.0 containing 728 mature rat miRNA probes.

RESULTS

Seventy-one miRNAs were down-regulated and 4 were up-regulated in the kidneys of DHCA rats [log2 (fold change, FC) > 1, P < 0.05]. Novel differentially expressed miRNAs, such as miRNA-3068, miR-1949 and miR-3473, were identified in the injured kidney tissues. Putative target genes of the down-regulated miR-30b-5p, miR-199a-5p, miR-148b-3p and miR-10a-3p were subjected to analyses of gene ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results indicated that these miRNAs targeted a large set of genes involved in essential biological processes related to AKI pathogenesis, such as apoptotic process and response to hypoxia, as well as genes implicated in critical signalling pathways, such as chemokine, lysosome and FoxO signalling pathways (false discovery rate-corrected, P < 0.05).

CONCLUSIONS

The identified 75 differentially expressed miRNAs hold the potential to serve as novel early markers and novel therapeutic targets for DHCA-AKI.

MicroRNA Biogenesis and Hedgehog-Patched Signaling Cooperate to Regulate an Important Developmental Transition in Granule Cell Development

The Dicer1, Dcr-1 homolog (Drosophila) gene encodes a type III ribonuclease required for the canonical maturation and functioning of microRNAs (miRNAs). Subsets of miRNAs are known to regulate normal cerebellar granule cell development, in addition to the growth and progression of medulloblastoma, a neoplasm that often originates from granule cell precursors. Multiple independent studies have also demonstrated that deregulation of Sonic Hedgehog (Shh)-Patched (Ptch) signaling, through miRNAs, is causative of granule cell pathologies. In the present study, we investigated the genetic interplay between miRNA biogenesis and Shh-Ptch signaling in granule cells of the cerebellum by way of the Cre/lox recombination system in genetically engineered models of Mus musculus (mouse). We demonstrate that, although the miRNA biogenesis and Shh-Ptch-signaling pathways, respectively, regulate the opposing growth processes of cerebellar hypoplasia and hyperplasia leading to medulloblastoma, their concurrent deregulation was nonadditive and did not bring the growth phenotypes toward an expected equilibrium. Instead, mice developed either hypoplasia or medulloblastoma, but of a greater severity. Furthermore, some genotypes were bistable, whereby subsets of mice developed hypoplasia or medulloblastoma. This implies that miRNAs and Shh-Ptch signaling regulate an important developmental transition in granule cells of the cerebellum. We also conclusively show that the Dicer1 gene encodes a haploinsufficient tumor suppressor gene for Ptch1-induced medulloblastoma, with the monoallielic loss of Dicer1 more severe than biallelic loss. These findings exemplify how genetic interplay between pathways may produce nonadditive effects with a substantial and unpredictable impact on biology. Furthermore, these findings suggest that the functional dosage of Dicer1 may nonadditively influence a wide range of Shh-Ptch-dependent pathologies.

RNA-Sequencing Analysis of Messenger RNA/MicroRNA in a Rabbit Aneurysm Model Identifies Pathways and Genes of Interest

BACKGROUND AND PURPOSE

Rabbit aneurysm models are used for the testing of embolization devices and elucidating the mechanisms of human intracranial aneurysm growth and healing. We used RNA-sequencing technology to identify genes relevant to induced rabbit aneurysm biology and to identify genes and pathways of potential clinical interest. This process included sequencing microRNAs, which are important regulatory noncoding RNAs.

MATERIALS AND METHODS

Elastase-induced saccular aneurysms were created at the origin of the right common carotid artery in 6 rabbits. Messenger RNA and microRNA were isolated from the aneurysm and from the control left common carotid artery at 12 weeks and processed by using RNA-sequencing technology. The results from RNA sequencing were analyzed by using the Ingenuity Pathway Analysis tool.

RESULTS

A total of 9396 genes were analyzed by using RNA sequencing, 648 (6.9%) of which were found to be significantly differentially expressed between the aneurysms and control tissues (P < .05; false-discovery rate, <0.01; fold change, >2 or <.5). Of these genes, 614 were mapped successfully, 143 were down-regulated, and 471 were up-regulated in the aneurysms as compared with controls. Using the same criteria for significance, 3 microRNAs were identified as down-regulated and 5 were identified as up-regulated. Pathway analysis associated these genes with inflammatory response, cellular migration, and coagulation, among other functions and pathologies.

CONCLUSIONS

RNA-sequencing analysis of rabbit aneurysms revealed differential regulation of some key pathways, including inflammation and antigen presentation. ANKRD1 and TACR1 were identified as genes of interest in the regulation of matrix metalloproteinases.

MicroRNAs in pediatric central nervous system embryonal neoplasms: the known unknown

MicroRNAs (miRNAs) are endogenous short non-coding RNAs that repress post-transcriptional regulation of gene expression, while embryonal central nervous system tumors are the foremost cause of mortality in children suffering from a neoplasm. MiRNAs and their regulatory mechanisms are new to understand, while pediatric CNS tumors are difficult to comprehend. Therefore, identification of the link between them composes a major scientific challenge. The present study, reviewed the current knowledge on the role of miRNA in pediatric CNS embryonal tumors, attempting to collect the existing information in one piece of work that could ideally be used as a guide for future reference and research.

MicroRNA signatures as biomarkers and therapeutic target for CNS embryonal tumors: the pros and the cons

Embryonal tumors of the central nervous system represent a heterogeneous group of childhood cancers with an unknown pathogenesis; diagnosis, on the basis of histological appearance alone, is controversial and patients’ response to therapy is difficult to predict. They encompass medulloblastoma, atypical teratoid/rhabdoid tumors and a group of primitive neuroectodermal tumors. All are aggressive tumors with the tendency to disseminate throughout the central nervous system. The large amount of genomic and molecular data generated over the last 5–10 years encourages optimism that new molecular targets will soon improve outcomes. Recent neurobiological studies have uncovered the key role of microRNAs (miRNAs) in embryonal tumors biology and their potential use as biomarkers is increasingly being recognized and investigated. However the successful use of microRNAs as reliable biomarkers for the detection and management of pediatric brain tumors represents a substantial challenge. This review debates the importance of miRNAs in the biology of central nervous systemembryonal tumors focusing on medulloblastoma and atypical teratoid/rhabdoid tumors and highlights the advantages as well as the limitations of their prospective application as biomarkers and candidates for molecular therapeutic targets.