Belonging to a network--microRNAs, extracellular vesicles, and the glioblastoma microenvironment

Glioma-Stem-Cell-Derived Exosomes Remodeled Glioma-Associated Macrophage via NEAT1/miR-125a/STAT3 Pathway

Glioblastoma (GBM), as the most common primary brain tumor, usually results in an extremely poor prognosis, in which glioma stem cells (GSCs) and their immunosuppressive microenvironment prominently intervene in the resistance to radiotherapy and chemotherapy that directly leads to tumor recurrence and shortened survival time. The specific mechanism through which exosomes generated from GSCs support the creation of an immunosuppressive microenvironment remains unknown, while it is acknowledged to be engaged in intercellular communication and the regulation of the glioma immunosuppressive microenvironment. The elevated expression of LncRNA-NEAT1 was found in glioma cells after radiotherapy, chemotherapy, and DNA damage stimulation, and NEAT1 could promote the malignant biological activities of GSCs. Emerging evidence suggests that lncRNAs may reply to external stimuli or DNA damage by playing a role in modulating different aspects of tumor biology. Our study demonstrated a promotive role of the carried NEAT1 by GSC-derived exosomes in the polarization of M2-like macrophages. Further experiments demonstrated the mediative role of miR-125a and its target gene STAT3 in NEAT1-induced polarization of M2-like macrophages that promote glioma progression. Our findings elucidate the mechanism by which GSCs influence the polarization of M2-like macrophages through exosomes, which may contribute to the formation of immunosuppressive microenvironments. Taken together, our study reveals the miR-125a-STAT3 pathway through which exosomal NEAT1 from treatment-resistant GSCs contributes to M2-like macrophage polarization, indicating the potential of exosomal NEAT1 for treating glioma.

From bench to bedside: The promising value of exosomes in precision medicine for CNS tumors

Exosomes are naturally present extracellular vesicles (EVs) released into the surrounding body fluids upon the fusion of polycystic and plasma membranes. They facilitate intercellular communication by transporting DNA, mRNA, microRNA, long non-coding RNA, circular RNA, proteins, lipids, and nucleic acids. They contribute to the onset and progression of Central Nervous System (CNS) tumors. In addition, they can be used as biomarkers of tumor proliferation, migration, and blood vessel formation, thereby affecting the Tumor Microenvironment (TME). This paper reviews the recent advancements in the diagnosis and treatment of exosomes in various CNS tumors, the promise and challenges of exosomes as natural carriers of CNS tumors, and the therapeutic prospects of exosomes in CNS tumors. Furthermore, we hope this research can contribute to the development of more targeted and effective treatments for central nervous system tumors.

MiR-128-3p - a gray eminence of the human central nervous system

MicroRNA-128-3p (miR-128-3p) is a versatile molecule with multiple functions in the physiopathology of the human central nervous system. Perturbations of miR-128-3p, which is enriched in the brain, contribute to a plethora of neurodegenerative disorders, brain injuries, and malignancies, as this miRNA is a crucial regulator of gene expression in the brain, playing an essential role in the maintenance and function of cells stemming from neuronal lineage. However, the differential expression of miR-128-3p in pathologies underscores the importance of the balance between its high and low levels. Significantly, numerous reports pointed to miR-128-3p as one of the most depleted in glioblastoma, implying it is a critical player in the disease's pathogenesis and thus may serve as a therapeutic agent for this most aggressive form of brain tumor. In this review, we summarize the current knowledge of the diverse roles of miR-128-3p. We focus on its involvement in the neurogenesis and pathophysiology of malignant and neurodegenerative diseases. We also highlight the promising potential of miR-128-3p as an antitumor agent for the future therapy of human cancers, including glioblastoma, and as the linchpin of brain development and function, potentially leading to the development of new therapies for neurological conditions.

A recognition of exosomes as regulators of epigenetic mechanisms in central nervous system diseases

Exosomes, vesicular structures originating from cells, participate in the conveyance of proteins and nucleic acids. Presently, the centrality of epigenetic modifications in neurological disorders is widely acknowledged. Exosomes exert influence over various epigenetic phenomena, thereby modulating post-transcriptional regulatory processes contingent upon their constituent makeup. Consequently, the heightened attention directed toward exosomes as instigators of epigenetic alterations has burgeoned in recent years. Notably, exosomes serve as vehicles for delivering methyltransferases to recipient cells. More significantly, non-coding RNAs, particularly microRNAs (miRNAs), represent pivotal contents within exosomes, wielding the capacity to influence the expression of diverse factors within the cerebral milieu. The transfer of these exosomal contents amidst brain cells, encompassing neuronal cells and microglia, assumes a critical role in the genesis and progression of neurological disorders, also, this role is not limited to neurological disorders, it may deal with any human disease, such as cancer, and cardiovascular diseases. This review will concentrate on elucidating the regulation of exosome-induced epigenetic events and its subsequent ramifications for neurological diseases. A more profound comprehension of the involvement of exosome-mediated epigenetic regulation in neurological disorders contributes to a heightened awareness of the etiology and advancement of cerebral afflictions.

Detailed role of microRNA-mediated regulation of PI3K/AKT axis in human tumors

The regulation of signal transmission and biological processes, such as cell proliferation, apoptosis, metabolism, migration, and angiogenesis are greatly influenced by the PI3K/AKT signaling pathway. Highly conserved endogenous non-protein-coding RNAs known as microRNAs (miRNAs) have the ability to regulate gene expression by inhibiting mRNA translation or mRNA degradation. MiRNAs serve key role in PI3K/AKT pathway as upstream or downstream target, and aberrant activation of this pathway contributes to the development of cancers. A growing body of research shows that miRNAs can control the PI3K/AKT pathway to control the biological processes within cells. The expression of genes linked to cancers can be controlled by the miRNA/PI3K/AKT axis, which in turn controls the development of cancer. There is also a strong correlation between the expression of miRNAs linked to the PI3K/AKT pathway and numerous clinical traits. Moreover, PI3K/AKT pathway-associated miRNAs are potential biomarkers for cancer diagnosis, therapy, and prognostic evaluation. The role and clinical applications of the PI3K/AKT pathway and miRNA/PI3K/AKT axis in the emergence of cancers are reviewed in this article.

Exosomal RNAs in the development and treatment of pituitary adenomas

Exosomes are small extracellular vesicles that carry various bioactive molecules including various RNAs that modulate the activities of recipient cells. It has drawn considerable attention as means of cell communication and drug delivery. Exosome plays important role in various tumors, but it is rarely summarized in pituitary adenoma (PA). PA is the second most common primary central nervous system tumor, and its recurrence and persistent postoperative hormone hypersecretion lead to compromised quality of life. How exactly exosomes impact tumor development and hormone secretion is important for the development of this tumor diagnosis and treatment. In this review, we discuss how exosomal RNAs impact PAs and their potential as future clinical therapies. In our literature review, first, we found that exosomal microRNA hsa-miR-1180-3p is a potential early biomarker for NFPAs. Since NFPAs are typically difficult to diagnose, this is an especially important finding. Second, exosomal protein transcripts are potential invasive biomarker, such as MMP1, N-cadherin, CDK6, RHOU, INSM1, and RASSF10. Third, exosomal contents such as hsa-miR-21-5p promote distant bone formation of GHPA patients. Fourth, tumor suppressors in the exosome constitute novel therapeutic application of exosome, including long noncoding RNA (lncRNA) H19, miR-149-5p, miR-99a-3p, and miR-423-5p. This review discusses the possible mechanisms of exosome and their contents in PA and promotes the use of exosomes in both clinical diagnosis and treatment of this tumor.

MicroRNA-based therapy for glioblastoma: Opportunities and challenges

Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor and is characterized by high mortality and morbidity rates and unpredictable clinical behavior. The disappointing prognosis for patients with GBM even after surgery and postoperative radiation and chemotherapy has fueled the search for specific targets to provide new insights into the development of modern therapies. MicroRNAs (miRNAs/miRs) act as oncomirs and tumor suppressors to posttranscriptionally regulate the expression of various genes and silence many target genes involved in cell proliferation, the cell cycle, apoptosis, invasion, stem cell behavior, angiogenesis, the microenvironment and chemo- and radiotherapy resistance, which makes them attractive candidates as prognostic biomarkers and therapeutic targets or agents to advance GBM therapeutics. However, one of the major challenges of successful miRNA-based therapy is the need for an effective and safe system to deliver therapeutic compounds to specific tumor cells or tissues in vivo, particularly systems that can cross the blood-brain barrier (BBB). This challenge has shifted gradually as progress has been achieved in identifying novel tumor-related miRNAs and their targets, as well as the development of nanoparticles (NPs) as new carriers to deliver therapeutic compounds. Here, we provide an up-to-date summary (in recent 5 years) of the current knowledge of GBM-related oncomirs, tumor suppressors and microenvironmental miRNAs, with a focus on their potential applications as prognostic biomarkers and therapeutic targets, as well as recent advances in the development of carriers for nontoxic miRNA-based therapy delivery systems and how they can be adapted for therapy.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Noncoding RNAs of Extracellular Vesicles in Tumor Angiogenesis: From Biological Functions to Clinical Significance

Extracellular vesicles (EVs) act as multifunctional regulators of intercellular communication and are involved in diverse tumor phenotypes, including tumor angiogenesis, which is a highly regulated multi-step process for the formation of new blood vessels that contribute to tumor proliferation. EVs induce malignant transformation of distinct cells by transferring DNAs, proteins, lipids, and RNAs, including noncoding RNAs (ncRNAs). However, the functional relevance of EV-derived ncRNAs in tumor angiogenesis remains to be elucidated. In this review, we summarized current research progress on the biological functions and underlying mechanisms of EV-derived ncRNAs in tumor angiogenesis in various cancers. In addition, we comprehensively discussed the potential applications of EV-derived ncRNAs as cancer biomarkers and novel therapeutic targets to tailor anti-angiogenic therapy.

Extracellular Vesicles Secreted by Glioma Stem Cells Are Involved in Radiation Resistance and Glioma Progression

Glioblastoma is the most aggressive brain tumour with short survival, partly due to resistance to conventional therapy. Glioma stem cells (GSC) are likely to be involved in treatment resistance, by releasing extracellular vesicles (EVs) containing specific molecular cargoes. Here, we studied the EVs secreted by glioma stem cells (GSC-EVs) and their effects on radiation resistance and glioma progression. EVs were isolated from 3 GSCs by serial centrifugation. NanoSight measurement, cryo-electron microscopy and live imaging were used to study the EVs size, morphology and uptake, respectively. The non-GSC glioma cell lines LN229 and U118 were utilised as a recipient cell model. Wound healing assays were performed to detect cell migration. Colony formation, cell viability and invadopodium assays were conducted to detect cell survival of irradiated recipient cells and cell invasion post GSC-EV treatment. NanoString miRNA global profiling was used to select for the GSC-EVs’ specific miRNAs. All three GSC cell lines secreted different amounts of EVs, and all expressed consistent levels of CD9 but different level of Alix, TSG101 and CD81. EVs were taken up by both LN229 and U118 recipient cells. In the presence of GSC-EVs, these recipient cells survived radiation exposure and initiated colony formation. After GSC-EVs exposure, LN229 and U118 cells exhibited an invasive phenotype, as indicated by an increase in cell migration. We also identified 25 highly expressed miRNAs in the GSC-EVs examined, and 8 of these miRNAs can target PTEN. It is likely that GSC-EVs and their specific miRNAs induced the phenotypic changes in the recipient cells due to the activation of the PTEN/Akt pathway. This study demonstrated that GSC-EVs have the potential to induce radiation resistance and modulate the tumour microenvironment to promote glioma progression. Future therapeutic studies should be designed to interfere with these GSC-EVs and their specific miRNAs.

Pediatric brain tumor cell lines exhibit miRNA-depleted, Y RNA-enriched extracellular vesicles

BACKGROUND

Medulloblastoma (MB) and diffuse infiltrative pontine glioma (DIPG) are malignant pediatric tumors. Extracellular vesicles (EVs) and their bioactive cargoes have been implicated in tumorigenesis. Most studies have focused on adult tumors, therefore the role of EVs and the noncoding RNA (ncRNA) landscape in pediatric brain tumors is not fully characterized. The overall aim of this pilot study was to isolate EVs from MB and DIPG patient-derived cell lines and to explore the small ncRNA transcriptome.

METHODS

EVs from 3 DIPG and 4 MB patient-derived cell lines were analyzed. High-throughput next generation sequencing interrogated the short non-coding RNA (ncRNA) transcriptome. Known and novel miRNAs were quantified. Differential expression analysis, in silico target prediction, and functional gene enrichment were performed.

RESULTS

EV secretomes from MB and DIPG patient-derived cell lines demonstrated discrete ncRNA biotypes. Notably, miRNAs were depleted and Y RNAs were enriched in EV samples. Hierarchical cluster analysis revealed high discrimination in miRNA expression between DIPG and MB cell lines and RNA-Seq identified novel miRNAs not previously implicated in MB or DIPG pathogenesis. Known and putative target genes of dysregulated miRNAs were identified. Functional annotation analysis of the target genes for differentially expressed EV-and parental-derived miRNAs revealed significant cancer-related pathway involvement.

CONCLUSIONS

This hypothesis-generating study demonstrated that pediatric brain tumor-derived cell lines secrete EVs comprised of various ncRNA cargoes. Validation of these findings in patient samples may provide new insights into the pediatric brain tumor microenvironment and identification of novel therapeutic candidates.

The effects of altered neurogenic microRNA levels and their involvement in the aggressiveness of periventricular glioblastoma

INTRODUCTION

Glioblastoma multiforme is the most common primary brain tumour, with the least favourable prognosis. Despite numerous studies and medical advances, it continues to be lethal, with an average life expectancy of 15 months after chemo-radiotherapy.

DEVELOPMENT

Recent research has addressed several factors associated with the diagnosis and prognosis of glioblastoma; one significant factor is tumour localisation, particularly the subventricular zone, which represents one of the most active neurogenic niches of the adult human brain. Glioblastomas in this area are generally more aggressive, resulting in unfavourable prognosis and a shorter life expectancy. Currently, the research into microRNAs (miRNA) has intensified, revealing different expression patterns under physiological and pathophysiological conditions. It has been reported that the expression levels of certain miRNAs, mainly those related to neurogenic processes, are dysregulated in oncogenic events, thus favouring gliomagenesis and greater tumour aggressiveness. This review discusses some of the most important miRNAs involved in subventricular neurogenic processes and their association with glioblastoma aggressiveness.

CONCLUSIONS

MiRNA regulation and function play an important role in the development and progression of glioblastoma; understanding the alterations of certain miRNAs involved in both differentiation and neural and glial maturation could help us to better understand the malignant characteristics of glioblastoma.

miR‑497/MIR497HG inhibits glioma cell proliferation by targeting CCNE1 and the miR‑588/TUSC1 axis

Emerging evidence has shown that microRNA (miR)-497 serves pivotal roles in tumorigenesis, cancer progression, metastasis and chemotherapy resistance in several types of cancer. In the present study, the expression and biological functions of miR-497 host gene (MIR497HG) were investigated in glioma tissue. The expression levels of miR-497 and MIR497HG were measured in glioma, adjacent non-cancerous and normal brain tissue and their association with the prognosis of patients with glioma were analyzed. The biological roles of miR-497 and MIR497HG were investigated in glioma cell lines. In addition, bioinformatics analysis, luciferase reporter assay and functional experiments were performed to identify and validate the downstream targets of miR-497 or MIR497HG. The expression levels of miR-497 and MIR497HG were downregulated in glioma tissue and cell lines compared with those in adjacent non-cancerous and normal brain tissue and normal human cortical neuron cell line. Patients with low miR-497 or MIR497HG expression levels exhibited a poor prognostic outcome. In addition, forced overexpression of miR-497 or MIR497HG significantly inhibited the proliferation and cell cycle progression of glioma cell lines. Furthermore, the results indicated that miR-497 and MIR497HG exerted their biological functions by direct targeting of cyclin E1 and miR-588/tumor suppressor candidate 1. In summary, the data indicated that miR-497 and MIR497HG served as tumor suppressors and may be used as potential therapeutic targets and prognostic biomarkers in glioma.

Inhibition of tumor progression and M2 microglial polarization by extracellular vesicle-mediated microRNA-124 in a 3D microfluidic glioblastoma microenvironment

Background: Glioblastoma (GBM) is one of the most aggressive types of brain cancer. GBM progression is closely associated with microglia activation; therefore, understanding the regulation of the crosstalk between human GBM and microglia may help develop effective therapeutic strategies. Elucidation of efficient delivery of microRNA (miRNA) via extracellular vesicles (EVs) and their intracellular communications is required for therapeutic applications in GBM treatment. Methods: We used human GBM cells (U373MG) and human microglia. MiRNA-124 was loaded into HEK293T-derived EVs (miR-124 EVs). Various anti-tumor effects (proliferation, metastasis, chemosensitivity, M1/M2 microglial polarization, and cytokine profile) were investigated in U373MG and microglia. Anti-tumor effect of miR-124 EVs was also investigated in five different patient-derived GBM cell lines (SNU-201, SNU-466, SNU-489, SNU-626, and SNU-1105). A three-dimensional (3D) microfluidic device was used to investigate the interactive microenvironment of the tumor and microglia. Results: MiR-124 EVs showed highly efficient anti-tumor effects both in GBM cells and microglia. The mRNA expression levels of tumor progression and M2 microglial polarization markers were decreased in response to miR-124 EVs. The events were closely related to signal transducer and activator of transcription (STAT) 3 signaling in both GBM and microglia. In 3D microfluidic experiments, both U373MG and microglia migrated to a lesser extent and showed less-elongated morphology in the presence of miR-124 EVs compared to the control. Analyses of changes in cytokine levels in the microfluidic GBM-microglia environment showed that the treatment with miR-124 EVs led to tumor suppression and anti-cancer immunity, thereby recruiting natural killer (NK) cells into the tumor. Conclusions: In this study, we demonstrated that EV-mediated miR-124 delivery exerted synergistic anti-tumor effects by suppressing the growth of human GBM cells and inhibiting M2 microglial polarization. These findings provide new insights toward a better understanding of the GBM microenvironment and provide substantial evidence for the development of potential therapeutic strategies using miRNA-loaded EVs.

The Role of Exosomal miRNAs in Glioma: Biological Function and Clinical Application

Gliomas are complex and heterogeneous central nervous system tumors with poor prognosis. Despite the increasing development of aggressive combination therapies, the prognosis of glioma is generally unsatisfactory. Exosomal microRNA (miRNA) has been successfully used in other diseases as a reliable biomarker and even therapeutic target. Recent studies show that exosomal miRNA plays an important role in glioma occurrence, development, invasion, metastasis, and treatment resistance. However, the association of exosomal miRNA between glioma has not been systemically characterized. This will provide a theoretical basis for us to further explore the relationship between exosomal miRNAs and glioma and also has a positive clinical significance in the innovative diagnosis and treatment of glioma.

Serum Exosomal microRNA-21, 222 and 124-3p as Noninvasive Predictive Biomarkers in Newly Diagnosed High-Grade Gliomas: A Prospective Study

Simple Summary

Diagnosis of relapse during post-surgery monitoring of patients with High-grade glioma is often challenging. This study was aimed to identify circulating biomarkers providing information about response to therapy and early diagnosis of progression during follow-up of these patients. Our findings, showing upregulation of exosomal miRNAs associated with relapse represent a proof of principle that these biomarkers may be clinically useful tools for diagnosing and monitoring of gliomas.

Abstract

Background: High-grade gliomas (HGG) are malignant brain tumors associated with frequent recurrent disease. Clinical management of HGG patients is currently devoid of blood biomarkers for early diagnosis, monitoring therapeutic effects and predicting recurrence. Different circulating miRNAs, both free and associated with exosomes, are described in patients with HGG. We previously identified miR-21, miR-222 and miR-124-3p purified from serum exosomes as molecular signature to help pre-operative clinical diagnosis and grading of gliomas. The aim of the present study was to verify this signature as a tool to assess the effect of treatment and for the early identification of progression in newly diagnosed HGG patients. Material and Methods: Major inclusion criteria were newly diagnosed, histologically confirmed HGG patients, no prior chemotherapy, ECOG PS 0-2 and patients scheduled for radiochemotherapy with temozolomide as first-line treatment after surgery. RANO criteria were used for response assessment. Serum was collected at baseline and subsequently at each neuroradiological assessment. mir-21, -222 and -124-3p expression in serum exosomes was measured in all samples. Results: A total number of 57 patients were enrolled; 41 were male, 52 with glioblastoma and 5 with anaplastic astrocytoma; 18 received radical surgery. HGG patients with higher exosomal miRNA expression displayed a statistically significant lower progression-free survival and overall survival. Increased expression of miR-21, -222 and -124-3p during post-operative follow-up was associated with HGG progression. Conclusions: These data indicate that miR-21, -222 and -124-3p in serum exosomes may be useful molecular biomarkers for complementing clinical evaluation of early tumor progression during post-surgical therapy in patients with HGG.

Gliomas Interact with Non-glioma Brain Cells via Extracellular Vesicles

Emerging evidence suggests that crosstalk between glioma cells and the brain microenvironment may influence brain tumor growth. To date, known reciprocal interactions among these cells have been limited to the release of paracrine factors. Combining a genetic strategy with longitudinal live imaging, we find that individual gliomas communicate with distinct sets of non-glioma cells, including glial cells, neurons, and vascular cells. Transfer of genetic material is achieved mainly through extracellular vesicles (EVs), although cell fusion also plays a minor role. We further demonstrate that EV-mediated communication leads to the increase of synaptic activity in neurons. Blocking EV release causes a reduction of glioma growth in vivo. Our findings indicate that EV-mediated interaction between glioma cells and non-glioma brain cells alters the tumor microenvironment and contributes to glioma development.

Potential of long non-coding RNAs as a therapeutic target and molecular markers in glioblastoma pathogenesis

Glioblastoma (GB) is by far the most hostile type of malignant tumor that primarily affects the brain and spine, derived from star-shaped glial cells that are astrocytes and oligodendrocytes. Despite of significant efforts in recent years in glioblastoma research, the clinical efficacy of existing medical intervention is still limited and very few potential diagnostic markers are available. Long non-coding RNAs (lncRNAs) that lacks protein-coding capabilities were previously thought to be "junk sequences" in mammalian genomes are quite indispensible epigenetic regulators that can positively or negatively regulate gene expression and nuclear architecture, with significant roles in the initiation and development of tumors. Nevertheless, the precise mechanism of these distortedly expressed lncRNAs in glioblastoma pathogenesis is not yet fully understood. Since the advent of high-throughput sequencing technologies, more and more research have elucidated that lncRNAs are one of the most promising prognostic biomarkers and therapeutic targets for glioblastoma. In this paper, I briefly outlined the existing findings of lncRNAs. And also summarizes the profiles of different lncRNAs that have been broadly classified in glioblastoma research, with emphasis on both their prognostic and therapeutic values.

The HOTAIR lncRNA: A remarkable oncogenic promoter in human cancer metastasis

Long non-coding RNA (lncRNA) is a new type of non-coding RNA that has an important regulatory influence on several human diseases, including cancer metastasis. HOX antisense intergenic RNA (HOTAIR), a newly discovered lncRNA, has an important effect on tumour proliferation, migration and metastasis. HOTAIR regulates cell proliferation, changes gene expression, and promotes tumour cell invasion and migration. However, its molecular mechanism of action remains unknown. The present review summarizes the molecular mechanism and role of HOTAIR in tumour invasion and metastasis, discusses the association between HOTAIR and tumour metastasis through different pathways, such as the transforming growth factor β, Wnt/β-catenin, PI3K/AKT/MAPK and vascular endothelial growth factor pathways, emphasizes the function of HOTAIR in human malignant tumour metastasis and provides a foundation for its application in the diagnosis, prognosis and medical treatment of various tumours.

Extracellular Vesicles Induce Mesenchymal Transition and Therapeutic Resistance in Glioblastomas through NF-κB/STAT3 Signaling

Glioblastoma (GBM) is the most common primary malignant brain tumor and despite optimal treatment, long-term survival remains uncommon. GBM can be roughly divided into three different molecular subtypes, each varying in aggressiveness and treatment resistance. Recent evidence shows plasticity between these subtypes in which the proneural (PN) glioma stem-like cells (GSCs) undergo transition into the more aggressive mesenchymal (MES) subtype, leading to therapeutic resistance. Extracellular vesicles (EVs) are membranous structures secreted by nearly every cell and are shown to play a key role in GBM progression by acting as multifunctional signaling complexes. Here, it is shown that EVs derived from MES cells educate PN cells to increase stemness, invasiveness, cell proliferation, migration potential, aggressiveness, and therapeutic resistance by inducing mesenchymal transition through nuclear factor-κB/signal transducer and activator of transcription 3 signaling. The findings could potentially help explore new treatment strategies for GBM and indicate that EVs may also play a role in mesenchymal transition of different tumor types.

Liquid biopsy in central nervous system tumors: the potential roles of circulating miRNA and exosomes

The Central nervous system (CNS) tumor still remains the most lethal cancer, and It is hard to diagnose at an earlier stage on most occasions. It is found that recurrent disease is finally observed in patients who occurred chemo-resistance after completely primary treatment. It is a challenge that monitoring treatment efficacy and tumor recurrence of CNS tumors are full of risks and difficulties by brain biopsies. However, the brain biopsies are considered as an invasive technique with low specificity and low sensitivity. In contrast, the liquid biopsy is based on blood and cerebrospinal fluid (CSF) test, which is going to acceptable among the patients through it's minimally invasive and serial bodily fluids. The advantages of liquid biopsy are to follow the development of tumors, provide new insights in real time, and accurate medical care. The major analytical constituents of liquid biopsy contain the Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating cell-free microRNAs (cfmiRNAs), and circulating exosomes. Liquid biopsy has been widely utilized in CNS tumors in recent years, and the CTCs and ctDNA have become the hot topics for researching. In this review, we are going to explain the clinical potential of liquid biopsy biomarkers in CNS tumor by testing circulating miRNAs and exosomes to evaluate diagnose, prognosis, and response to treatment.

miR-504 modulates the stemness and mesenchymal transition of glioma stem cells and their interaction with microglia via delivery by extracellular vesicles

Glioblastoma (GBM) is a highly aggressive tumor with poor prognosis. A small subpopulation of glioma stem cells (GSCs) has been implicated in radiation resistance and tumor recurrence. In this study we analyzed the expression of miRNAs associated with the functions of GSCs using miRNA microarray analysis of these cells compared with human neural stem cells. These analyses identified gene clusters associated with glioma cell invasiveness, axonal guidance, and TGF-β signaling. miR-504 was significantly downregulated in GSCs compared with NSCs, its expression was lower in GBM compared with normal brain specimens and further decreased in the mesenchymal glioma subtype. Overexpression of miR-504 in GSCs inhibited their self-renewal, migration and the expression of mesenchymal markers. The inhibitory effect of miR-504 was mediated by targeting Grb10 expression which acts as an oncogene in GSCs and GBM. Overexpression of exogenous miR-504 resulted also in its delivery to cocultured microglia by GSC-secreted extracellular vesicles (EVs) and in the abrogation of the GSC-induced polarization of microglia to M2 subtype. Finally, miR-504 overexpression prolonged the survival of mice harboring GSC-derived xenografts and decreased tumor growth. In summary, we identified miRNAs and potential target networks that play a role in the stemness and mesenchymal transition of GSCs and the miR-504/Grb10 pathway as an important regulator of this process. Overexpression of miR-504 exerted antitumor effects in GSCs as well as bystander effects on the polarization of microglia via delivery by EVs.

Modeling the Interaction between the Microenvironment and Tumor Cells in Brain Tumors

Despite considerable recent advances in understanding and treating many other cancers, malignant brain tumors remain associated with low survival or severe long-term sequelae. Limited progress, including development of immunotherapies, relates in part to difficulties in accurately reproducing brain microenvironment with current preclinical models. The cellular interactions among resident microglia, recruited tumor-associated macrophages, stromal cells, glial cells, neurons, and cancer cells and how they affect tumor growth or behavior are emerging, yet many questions remain. The role of the blood-brain barrier, extracellular matrix components, and heterogeneity among tumor types and within different regions of a single tumor further complicate the matter. Here, we focus on brain microenvironment features impacted by tumor biology. We also discuss limits of current preclinical models and how complementary models, such as humanized animals and organoids, will allow deeper mechanistic insights on cancer biology, allowing for more efficient testing of therapeutic strategies, including immunotherapy, for brain cancers.

Inter and Intracellular mitochondrial trafficking in health and disease

Neurons and glia maintain central nervous system (CNS) homeostasis through diverse mechanisms of intra- and intercellular signaling. Some of these interactions include the exchange of soluble factors between cells via direct cell-to-cell contact for both short and long-distance transfer of biological materials. Transcellular transfer of mitochondria has emerged as a key example of this communication. This transcellular transfer of mitochondria are dynamically involved in the cellular and tissue response to CNS injury and play beneficial roles in recovery. This review highlights recent research addressing the cause and effect of intra- and intercellular mitochondrial transfer with a specific focus on the future of mitochondrial transplantation therapy. We believe that mitochondrial transfer plays a crucial role during bioenergetic crisis/deficit, but the quality, quantity and mode of mitochondrial transfer determines the protective capacity for the receiving cells. Mitochondrial transplantation is a new treatment paradigm and will overcome the major bottleneck of traditional approach of correcting mitochondria-related disorders.

Practical Review on Preclinical Human 3D Glioblastoma Models: Advances and Challenges for Clinical Translation

Fifteen years after the establishment of the Stupp protocol as the standard of care to treat glioblastomas, no major clinical advances have been achieved and increasing patient’s overall survival remains a challenge. Nevertheless, crucial molecular and cellular findings revealed the intra-tumoral and inter-tumoral complexities of these incurable brain tumors, and the essential role played by cells of the microenvironment in the lack of treatment efficacy. Taking this knowledge into account, fulfilling gaps between preclinical models and clinical samples is necessary to improve the successful rate of clinical trials. Since the beginning of the characterization of brain tumors initiated by Bailey and Cushing in the 1920s, several glioblastoma models have been developed and improved. In this review, we focused on the most widely used 3D human glioblastoma models, including spheroids, tumorospheres, organotypic slices, explants, tumoroids and glioblastoma-derived from cerebral organoids. We discuss their history, development and especially their usefulness.

Oxidative Stress-Part of the Solution or Part of the Problem in the Hypoxic Environment of a Brain Tumor

Rapid growth of brain tumors such as glioblastoma often results in oxygen deprivation and the emergence of hypoxic zones. In consequence, the enrichment of reactive oxygen species occurs, harming nonmalignant cells and leading them toward apoptotic cell death. However, cancer cells survive such exposure and thrive in a hypoxic environment. As the mechanisms responsible for such starkly different outcomes are not sufficiently explained, we aimed to explore what transcriptome rearrangements are used by glioblastoma cells in hypoxic areas. Using metadata analysis of transcriptome in different subregions of the glioblastoma retrieved from the Ivy Glioblastoma Atlas Project, we created the reactive oxygen species-dependent map of the transcriptome. This map was then used for the analysis of differential gene expression in the histologically determined cellular tumors and hypoxic zones. The gene ontology analysis cross-referenced with the clinical data from The Cancer Genome Atlas revealed that the metabolic shift is one of the major prosurvival strategies applied by cancer cells to overcome hypoxia-related cytotoxicity.

Relationship between Sphk1/S1P and microRNAs in human cancers

Sphingosine kinases type 1 (SphK1) is a key enzyme in the phosphorylation of sphingosine to sphingosine 1-phosphate (S1P). Different abnormalities in SphK1 functions may correspond with poor prognosis in various cancers. Additionally, upregulated SphK1/S1P could promote cancer cell proliferation, angiogenesis, mobility, invasion, and metastasis. MicroRNAs as conserved small noncoding RNAs play major roles in cancer initiation, progression, metastasis, etc. Their posttranscriptionally mechanisms could affect the development of cancer growth or tumorigenesis suppression. The growing number of studies has described that various microRNAs can be regulated by SphK1, and its expression level can also be regulated by microRNAs. In this review, the relationship of SphK1 and microRNA functions and their interaction in human malignancies have been discussed. Based on them novel treatment strategies can be introduced.

Survival Risk Prediction Models of Gliomas Based on IDH and 1p/19q

Gliomas have been classified into different molecular subtypes based on their molecular features. To explore the prognostic factors of different subtypes of gliomas, we performed a univariate survival analysis based on the RNA-seq data of 653 patients obtained from The Cancer Genome Atlas. We identified 12205 (20.18%), 6125 (10.13%) and 5206 (8.61%) genes associated with the overall survival (OS) of the IDH-wildtype, IDH-mutation 1p/19q intact and IDH-mutation 1p/19q codeletion gliomas, respectively. Pathway enrichment analysis revealed that OS related genes were mainly involved in alcoholism, systemic lupus erythematosus, hematopoietic cell lineage and diabetes. The OS related genes were further selected using Lasso regression, and three prognostic risk score models were constructed to effectively predict the OS of the patients with different subtypes of gliomas. In total, 76 signature genes were identified and were selected to construct the three models. Moreover, neither of the 76 genes overlapped between different models, which suggested the enormous difference among the three subtypes, although some signature genes (SERPINA5, RP11.229A12.2 and RP11.62F24.2) were also identified as the OS related genes in different glioma subtypes. Interestingly, five genes (RP11.229A12.2, RP11.62F24.2, C3orf67, RP11.275H4.1 and TBX3) played opposing roles (protective or risk factor) in different subtypes. Additionally, the prognosis models consisted of a substantial proportion of non-coding RNA (58.74%, 70.13% and 58.11% in the IDH-wildtype, IDH-mutation 1p/19q intact and IDH-mutation 1p/19q codeletion). Furthermore, multivariate analysis integrating clinical variables demonstrated that risk group predicted by the prognostic models was an independent prognostic factor for gliomas. In conclusion, we have constructed and validated three models that have the potential to predict the prognosis of glioma patients. The genes and pathways identified in this study require further investigation for their underlying mechanisms and potential clinical significance in improving the OS of the glioma patients.

Exosomal noncoding RNAs in Glioma: biological functions and potential clinical applications

Gliomas are complex and heterogeneous brain tumors with poor prognosis. Glioma cells can communicate with their surroundings to create a tumor-permissive microenvironment. Exosomes represent a new means of intercellular communication by delivering various bioactive molecules, including proteins, lipids and nucleic acids, and participate in tumor initiation and progression. Noncoding RNAs (ncRNAs) including microRNA, long-noncoding RNA, and circular RNA, account for a large portion of human transcriptome and play important roles in various pathophysiological processes, especially in cancers. In addition, ncRNAs can be selectively packaged, secreted and transferred between cells in exosomes and modulate numerous hallmarks of glioma, such as proliferation, invasion, angiogenesis, immune-escape, and treatment resistance. Hence, the strategies of specifically targeting exosomal ncRNAs could be attractive therapeutic options. Exosomes are able to cross the blood brain barrier (BBB), and are readily accessible in nearly all types of human biofluids, which make them the promising biomarkers for gliomas. Additionally, given the biocompatibility of exosomes, they can be engineered to deliver therapeutic factors, such as RNA, proteins and drugs, to target cells for therapeutic applications. Here, we reviewed current research on the roles of exosomal ncRNAs in glioma progression. We also discussed their potential clinical applications as novel biomarkers and therapeutics.

Neisseria meningitidis Induces Pathology-Associated Cellular and Molecular Changes in Trigeminal Schwann Cells

Neisseria meningitidis, a common cause of sepsis and bacterial meningitis, infects the meninges and central nervous system (CNS), primarily via paracellular traversal across the blood-brain barrier (BBB) or blood-cerebrospinal fluid barrier. N. meningitidis is often present asymptomatically in the nasopharynx, and the nerves extending between the nasal cavity and the brain constitute an alternative route by which the meningococci may reach the CNS. To date, the cellular mechanisms involved in nerve infection are not fully understood. Peripheral nerve glial cells are phagocytic and are capable of eliminating microorganisms, but some pathogens may be able to overcome this protection mechanism and instead infect the glia, causing cell death or pathology. Here, we show that N. meningitidis readily infects trigeminal Schwann cells (the glial cells of the trigeminal nerve) in vitro in both two-dimensional and three-dimensional cell cultures. Infection of trigeminal Schwann cells may be one mechanism by which N. meningitidis is able to invade the CNS. Infection of the cells led to multinucleation and the appearance of atypical nuclei, with the presence of horseshoe nuclei and the budding of nuclei increasing over time. Using sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics followed by bioinformatics pathway analysis, we showed that N. meningitidis induced protein alterations in the glia that were associated with altered intercellular signaling, cell-cell interactions, and cellular movement. The analysis also suggested that the alterations in protein levels were consistent with changes occurring in cancer. Thus, infection of the trigeminal nerve by N. meningitidis may have ongoing adverse effects on the biology of Schwann cells, which may lead to pathology.

Differential Expression of miRNAs in Hypoxia ("HypoxamiRs") in Three Canine High-Grade Glioma Cell Lines

Dogs with spontaneous high-grade gliomas increasingly are being proposed as useful large animal pre-clinical models for the human disease. Hypoxia is a critical microenvironmental condition that is common in both canine and human high-grade gliomas and drives increased angiogenesis, chemo- and radioresistance, and acquisition of a stem-like phenotype. Some of this effect is mediated by the hypoxia-induced expression of microRNAs, small (~22 nucleotides long), non-coding RNAs that can modulate gene expression through interference with mRNA translation. Using an in vitro model with three canine high-grade glioma cell lines (J3T, SDT3G, and G06A) exposed to 72 h of 1.5% oxygen vs. standard 20% oxygen, we examined the global “hypoxamiR” profile using small RNA-Seq and performed pathway analysis for targeted genes using both Panther and NetworkAnalyst. Important pathways include many that are well-established as being important in glioma biology, general cancer biology, hypoxia, angiogenesis, immunology, and stem-ness, among others. This work provides the first examination of the effect of hypoxia on miRNA expression in the context of canine glioma, and highlights important similarities with the human disease.

Peptidylarginine Deiminase Isozyme-Specific PAD2, PAD3 and PAD4 Inhibitors Differentially Modulate Extracellular Vesicle Signatures and Cell Invasion in Two Glioblastoma Multiforme Cell Lines

Glioblastoma multiforme (GBM) is an aggressive adult brain tumour with poor prognosis. Roles for peptidylarginine deiminases (PADs) in GBM have recently been highlighted. Here, two GBM cell lines were treated with PAD2, PAD3 and PAD4 isozyme-specific inhibitors. Effects were assessed on extracellular vesicle (EV) signatures, including EV-microRNA cargo (miR21, miR126 and miR210), and on changes in cellular protein expression relevant for mitochondrial housekeeping (prohibitin (PHB)) and cancer progression (stromal interaction molecule 1 (STIM-1) and moesin), as well as assessing cell invasion. Overall, GBM cell-line specific differences for the three PAD isozyme-specific inhibitors were observed on modulation of EV-signatures, PHB, STIM-1 and moesin protein levels, as well as on cell invasion. The PAD3 inhibitor was most effective in modulating EVs to anti-oncogenic signatures (reduced miR21 and miR210, and elevated miR126), to reduce cell invasion and to modulate protein expression of pro-GBM proteins in LN229 cells, while the PAD2 and PAD4 inhibitors were more effective in LN18 cells. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for deiminated proteins relating to cancer, metabolism and inflammation differed between the two GBM cell lines. Our findings highlight roles for the different PAD isozymes in the heterogeneity of GBM tumours and the potential for tailored PAD-isozyme specific treatment.

The effects of altered neurogenic microRNA levels and their involvement in the aggressiveness of periventricular glioblastoma

INTRODUCTION

Glioblastoma multiforme is the most common primary brain tumour, with the least favourable prognosis. Despite numerous studies and medical advances, it continues to be lethal, with an average life expectancy of 15 months after chemo-radiotherapy.

DEVELOPMENT

Recent research has addressed several factors associated with the diagnosis and prognosis of glioblastoma; one significant factor is tumour localisation, particularly the subventricular zone, which represents one of the most active neurogenic niches of the adult human brain. Glioblastomas in this area are generally more aggressive, resulting in unfavourable prognosis and a shorter life expectancy. Currently, the research into microRNAs (miRNA) has intensified, revealing different expression patterns under physiological and pathophysiological conditions. It has been reported that the expression levels of certain miRNAs, mainly those related to neurogenic processes, are dysregulated in oncogenic events, thus favouring gliomagenesis and greater tumour aggressiveness. This review discusses some of the most important miRNAs involved in subventricular neurogenic processes and their association with glioblastoma aggressiveness.

CONCLUSIONS

MiRNA regulation and function play an important role in the development and progression of glioblastoma; understanding the alterations of certain miRNAs involved in both differentiation and neural and glial maturation could help us to better understand the malignant characteristics of glioblastoma.

Blocking lncRNA MALAT1/miR-199a/ZHX1 Axis Inhibits Glioblastoma Proliferation and Progression

Zinc fingers and homeoboxes 1 (ZHX1) is a transcription repressor that has been implicated in the tumorigenesis and progression of diverse tumors. The functional role and regulating mechanism of ZHX1 has not been elucidated in glioblastoma (GBM). Previous reports have suggested that a large number of non-coding RNAs play a vital role in glioma initiation and progression. This study aimed to investigate the functional role and co-regulatory mechanisms of the metastasis-associated lung adenocarcinoma transcript-1 (MALAT1)/ microRNA-199a (miR-199a)/ZHX1 axis in GBM. We analyzed the expression of the MALAT1/miR-199a/ZHX1 axis and its correlation with patients' overall survival using two different glioma gene-expression datasets. A series of in vitro and in vivo studies including dual luciferase reporter assay, fluorescence in situ hybridization (FISH), RNA immunoprecipitation, and pull-down experiments were completed to elucidate the biological significance of the MALAT1/miR-199a/ZHX1 axis in promoting glioma proliferation and progression. Elevated ZHX1 expression correlated with poor prognosis in GBM patients, and in vitro studies demonstrated that ZHX1 attenuated GBM cell apoptosis by downregulation of pro-apoptotic protein (Bax) and upregulation of anti-apoptotic protein (Bcl-2). Furthermore, knockdown of MALAT1 inhibited GBM proliferation and progression in vitro and reduced tumor volume and prolonged survival in an orthotopic GBM murine model. Finally, we demonstrated that MALAT1 promoted ZHX1 expression via acting as a competing endogenous RNA by sponging miR-199a. The MALAT1/miR-199a/ZHX1 axis promotes GBM cell proliferation and progression in vitro and in vivo, and its expression negatively correlates with GBM patient survival. Blocking the MALAT1/miR-199a/ZHX1 axis can serve as a novel therapeutic strategy for treating GBM.

LncRNA HOTAIR in Tumor Microenvironment: What Role?

lncRNAs participate in many cellular processes, including regulation of gene expression at the transcriptional and post-transcriptional levels. In addition, many lncRNAs can contribute to the development of different human diseases including cancer. The tumor microenvironment (TME) plays an important role during tumor growth and metastatic progression, and most of these lncRNAs have a key function in TME intracellular signaling. Among the numerous identified lncRNAs, several experimental evidences have shown the fundamental role of the lncRNA HOTAIR in carcinogenesis, also highlighting its use as a circulating biomarker. In this review we described the contribution of HOTAIR in the TME modulation, highlighting its relation with cellular and non-cellular components during tumor evolution and progression.

MicroRNA-451 Inhibits Migration of Glioblastoma while Making It More Susceptible to Conventional Therapy

Malignant glioblastoma (GBM, glioma) is the most common and aggressive primary adult brain tumor. The prognosis of GBM patients remains poor, despite surgery, radiation and chemotherapy. The major obstacles for successful remedy are invasiveness and therapy resistance of GBM cells. Invasive glioma cells leave primary tumor core and infiltrate surrounding normal brain leading to inevitable recurrence, even after surgical resection, radiation and chemotherapy. Therapy resistance allowing for selection of more aggressive and resistant sub-populations including GBM stem-like cells (GSCs) upon treatment is another serious impediment to successful treatment. Through their regulation of multiple genes, microRNAs can orchestrate complex programs of gene expression and act as master regulators of cellular processes. MicroRNA-based therapeutics could thus impact broad cellular programs, leading to inhibition of invasion and sensitization to radio/chemotherapy. Our data show that miR-451 attenuates glioma cell migration in vitro and invasion in vivo. In addition, we have found that miR-451 sensitizes glioma cells to conventional chemo- and radio-therapy. Our data also show that miR-451 is regulated in vivo by AMPK pathway and that AMPK/miR-451 loop has the ability to switch between proliferative and migratory pattern of glioma cells behavior. We therefore postulate that AMPK/miR-451 negative reciprocal feedback loop allows GBM cells/GSCs to adapt to tumor “ecosystem” by metabolic and behavioral flexibility, and that disruption of such a loop reduces invasiveness and diminishes therapy resistance.

Cannabidiol Affects Extracellular Vesicle Release, miR21 and miR126, and Reduces Prohibitin Protein in Glioblastoma Multiforme Cells

Glioblastoma multiforme (GBM) is the most common and aggressive form of primary malignant brain tumor in adults, with poor prognosis. Extracellular vesicles (EVs) are key-mediators for cellular communication through transfer of proteins and genetic material. Cancers, such as GBM, use EV release for drug-efflux, pro-oncogenic signaling, invasion and immunosuppression; thus the modulation of EV release and cargo is of considerable clinical relevance. As EV-inhibitors have been shown to increase sensitivity of cancer cells to chemotherapy, and we recently showed that cannabidiol (CBD) is such an EV-modulator, we investigated whether CBD affects EV profile in GBM cells in the presence and absence of temozolomide (TMZ). Compared to controls, CBD-treated cells released EVs containing lower levels of pro-oncogenic miR21 and increased levels of anti-oncogenic miR126; these effects were greater than with TMZ alone. In addition, prohibitin (PHB), a multifunctional protein with mitochondrial protective properties and chemoresistant functions, was reduced in GBM cells following 1 h CBD treatment. This data suggests that CBD may, via modulation of EVs and PHB, act as an adjunct to enhance treatment efficacy in GBM, supporting evidence for efficacy of cannabinoids in GBM.

MicroRNA in Brain pathology: Neurodegeneration the Other Side of the Brain Cancer

The mammalian brain is made up of billions of neurons and supporting cells (glial cells), intricately connected. Molecular perturbations often lead to neurodegeneration by progressive loss of structure and malfunction of neurons, including their death. On the other side, a combination of genetic and cellular factors in glial cells, and less frequently in neurons, drive oncogenic transformation. In both situations, microenvironmental niches influence the progression of diseases and therapeutic responses. Dynamic changes that occur in cellular transcriptomes during the progression of developmental lineages and pathogenesis are controlled through a variety of regulatory networks. These include epigenetic modifications, signaling pathways, and transcriptional and post-transcriptional mechanisms. One prominent component of the latter is small non-coding RNAs, including microRNAs, that control the vast majority of these networks including genes regulating neural stemness, differentiation, apoptosis, projection fates, migration and many others. These cellular processes are also profoundly dependent on the microenvironment, stemness niche, hypoxic microenvironment, and interactions with associated cells including endothelial and immune cells. Significantly, the brain of all other mammalian organs expresses the highest number of microRNAs, with an additional gain in expression in the early stage of neurodegeneration and loss in expression in oncogenesis. However, a mechanistic explanation of the concept of an apparent inverse correlation between the odds of cancer and neurodegenerative diseases is only weakly developed. In this review, we thus will discuss widespread de-regulation of microRNAome observed in these two major groups of brain pathologies. The deciphering of these intricacies is of importance, as therapeutic restoration of pre-pathological microRNA landscape in neurodegeneration must not lead to oncogenesis and vice versa. We thus focus on microRNAs engaged in cellular processes that are inversely regulated in these diseases. We also aim to define the difference in microRNA networks between pro-survival and pro-apoptotic signaling in the brain.

Protein Phosphatases-A Touchy Enemy in the Battle Against Glioblastomas: A Review

Glioblastoma (GBM) is the most common malignant tumor arising from brain parenchyma. Although many efforts have been made to develop therapies for GBM, the prognosis still remains poor, mainly because of the difficulty in total resection of the tumor mass from brain tissue and the resistance of the residual tumor against standard chemoradiotherapy. Therefore, novel adjuvant therapies are urgently needed. Recent genome-wide analyses of GBM cases have clarified molecular signaling mechanisms underlying GBM biology. However, results of clinical trials targeting phosphorylation-mediated signaling have been unsatisfactory to date. Protein phosphatases are enzymes that antagonize phosphorylation signaling by dephosphorylating phosphorylated signaling molecules. Recently, the critical roles of phosphatases in the regulation of oncogenic signaling in malignant tumor cells have been reported, and tumorigenic roles of deregulated phosphatases have been demonstrated in GBM. However, a detailed mechanism underlying phosphatase-mediated signaling transduction in the regulation of GBM has not been elucidated, and such information is necessary to apply phosphatases as a therapeutic target for GBM. This review highlights and summarizes the phosphatases that have crucial roles in the regulation of oncogenic signaling in GBM cells.

Peptidylarginine Deiminases Post-Translationally Deiminate Prohibitin and Modulate Extracellular Vesicle Release and MicroRNAs in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most aggressive form of adult primary malignant brain tumour with poor prognosis. Extracellular vesicles (EVs) are a key-mediator through which GBM cells promote a pro-oncogenic microenvironment. Peptidylarginine deiminases (PADs), which catalyze the post-translational protein deimination of target proteins, are implicated in cancer, including via EV modulation. Pan-PAD inhibitor Cl-amidine affected EV release from GBM cells, and EV related microRNA cargo, with reduced pro-oncogenic microRNA21 and increased anti-oncogenic microRNA126, also in combinatory treatment with the chemotherapeutic agent temozolomide (TMZ). The GBM cell lines under study, LN18 and LN229, differed in PAD2, PAD3 and PAD4 isozyme expression. Various cytoskeletal, nuclear and mitochondrial proteins were identified to be deiminated in GBM, including prohibitin (PHB), a key protein in mitochondrial integrity and also involved in chemo-resistance. Post-translational deimination of PHB, and PHB protein levels, were reduced after 1 h treatment with pan-PAD inhibitor Cl-amidine in GBM cells. Histone H3 deimination was also reduced following Cl-amidine treatment. Multifaceted roles for PADs on EV-mediated pathways, as well as deimination of mitochondrial, nuclear and invadopodia related proteins, highlight PADs as novel targets for modulating GBM tumour communication.

Extracellular Vesicles as Conduits of Non-Coding RNA Emission and Intercellular Transfer in Brain Tumors

Non-coding RNA (ncRNA) species have emerged in as molecular fingerprints and regulators of brain tumor pathogenesis and progression. While changes in ncRNA levels have been traditionally regarded as cell intrinsic there is mounting evidence for their extracellular and paracrine function. One of the key mechanisms that enables ncRNA to exit from cells is their selective packaging into extracellular vesicles (EVs), and trafficking in the extracellular space and biofluids. Vesicular export processes reduce intracellular levels of specific ncRNA in EV donor cells while creating a pool of EV-associated ncRNA in the extracellular space and biofluids that enables their uptake by other recipient cells; both aspects have functional consequences. Cancer cells produce several EV subtypes (exosomes, ectosomes), which differ in their ncRNA composition, properties and function. Several RNA biotypes have been identified in the cargo of brain tumor EVs, of which microRNAs are the most studied, but other species (snRNA, YRNA, tRNA, and lncRNA) are often more abundant. Of particular interest is the link between transforming oncogenes and the biogenesis, cargo, uptake and function of tumor-derived EV, including EV content of oncogenic RNA. The ncRNA repertoire of EVs isolated from cerebrospinal fluid and serum is being developed as a liquid biopsy platform in brain tumors.

Inhibition of microRNA-299-5p sensitizes glioblastoma cells to temozolomide via the MAPK/ERK signaling pathway

Glioblastomas (GBMs) are a lethal class of brain cancer, with a median survival <15 months in spite of therapeutic advances. The poor prognosis of GBM is largely attributed to acquired chemotherapy resistance, and new strategies are urgently needed to target resistant glioma cells. Here we report a role for miR-299-5p in GBM. The level of miR-299-5p expression was detected in glioma specimens and cell lines by qRT-PCR. Luciferase reporter assays and Western blots were performed to verify GOLPH3 as a direct target of miR-299-5p. In vitro cell proliferation, invasion, cell cycle distribution, and apoptosis were assessed to determine whether or not miR-299-5p knockdown sensitized GBM cells to temozolomide (TMZ). We demonstrated that miR-299-5p levels were up-regulated in the GBM groups compared with the normal control group. The highest expression of miR-129-5p occurred in the highest GBM stage. miR-299-5p knockdown significantly inhibited the MAPK/extracellular signal-regulated kinase (ERK) signaling pathway. We also showed that miR-299-5p knockdown enhanced sensitivity of GBM cells to TMZ both in vitro and in vivo by inhibiting cell proliferation and invasion and promoting apoptosis. In addition, we demonstrated that GOLPH3 is a novel functional target of miR-299-5p GOLPH3 regulates the MAPK/ERK axis under miR-299-5p regulation. In conclusion, we identified a link between miR-299-5p expression and the GOLPH3/MAPK/ERK axis, thus illustrating a novel role for miR-299-5p in GBM.

MicroRNAs as biomarkers for human glioblastoma: progress and potential

Glioblastoma multiforme (GBM) is the most common malignant glioma. Despite innovative research efforts in tumor therapy, the outcome for most diagnosed patients remains poor; therefore, early diagnosis of GBM is the most effective method for achieving better patient outcomes. In recent years, combined research efforts including cellular, molecular, genetic, and bioinformatics methods have been used to investigate GBM, and the results show that variations in miRNA expression occur in GBM tissues and biological fluids. Some highly stable miRNAs circulate in the blood and cerebrospinal fluid (CSF) of both healthy individuals and diagnosed patients, thus raising the possibility that miRNAs may serve as novel diagnostic markers. In addition, increased understanding of the miRNA and mRNA interactions involved in GBM progression may lead to discovering predictive biomarkers, some of which are clinically relevant for targeted therapy and predicting prognosis. However, as this field is relatively new, some studies have yielded conflicting results. To progress in the field, different advanced techniques must be combined, including bioinformatics methods and molecular and cellular techniques. In addition, we must overcome the various challenges in non-invasive GBM biomarker detection. Here, we discuss the progress and potential of miRNAs as biomarkers for GBM and related signaling pathways. Studying the clinical relevance and applicability of these biomarkers may alter GBM patient diagnosis and treatment.

Overexpression of the Kininogen-1 inhibits proliferation and induces apoptosis of glioma cells

Background

Glioma is the most common primary central nervous system tumor derived from glial cells. Kininogen-1 (KNG1) can exert antiangiogenic properties and inhibit proliferation of endothelial cells. The effect of KNG1 on the glioma is rarely reported, so our purpose in to explore its mechanism in glioma cells.

Methods

The differentially expressed genes (DEGs) were identified based on The Cancer Genome Atlas (TCGA) database. The KNG1-vector was transfected into the two glioma cells. The viability, apoptosis and cell cycle of glioma cells and microvessel density (MVD) were detected by cell counting kit-8 assay, flow cytometry and immunohistochemistry, respectively. The expression were measured by quantitative real-time PCR and Western blot, respectively. A tumor mouse model was established to determine apoptosis rate of brain tissue by terminal deoxynucleotidyl transfer-mediated dUTP nick end labeling (TUNEL) analysis.

Results

KNG1 was identified as the core gene and lowly expressed in the glioma cells. Overexpression of KNG1 inhibited cell viability and angiogenesis of glioma cells. Overexpression of KNG1 promoted the apoptosis and G1 phase cell cycle arrest of glioma cells. Moreover, the expressions of VEGF, cyclinD1, ki67, caspase-3/9 and XIAP were regulated by overexpression of KNG1. In addition, overexpression of KNG1 inhibited the activity of PI3K/Akt. Furthermore, overexpression of KNG1 decreased the tumor growth and promoted the apoptosis of decreased by overexpression of KNG1 in vivo. .

Conclusions

Overexpression of KNG1 suppresses glioma progression by inhibiting the proliferation and promoting apoptosis of glioma cells, providing a therapeutic strategy for the malignant glioma.

Molecular subtypes and differentiation programmes of glioma stem cells as determinants of extracellular vesicle profiles and endothelial cell-stimulating activities

We have previously uncovered the impact of oncogenic and differentiation processes on extracellular vesicles (EVs) in cancer. This is of interested in the context of glioma stem cells (GSC) that are responsible for recurrent nature of glioblastoma multiforme (GBM), while retaining the potential to undergo differentiation and self renewal.  GSCs reside in vascular niches where they interact with endothelial cells through a number of mediators including bioactive cargo of EVs. GSCs can be classified as proneural (PN) or mesenchymal (MES) subtypes on the basis of their gene expression profiles and distinct biological characteristics. In the present study we investigated how GSC diversity and differentiation programmes influence their EV-mediated communication potentials. Indeed, molecular subtypes of GBMs and GSCs differ with respect to their expression of EV-related genes (vesiculome) and GSCs with PN or MES phenotypes produce EVs with markedly different characteristics, marker profiles, proteomes and endothelial stimulating activities. For example, while EVs of PN GSC are largely devoid of exosomal markers their counterparts from MES GSCs express ample CD9, CD63 and CD81 tetraspanins. In both GSC subtypes serum-induced differentiation results in profound, but distinct changes of cellular phenotypes including the enhanced EV production, reconfiguration of their proteomes and the related functional pathways. Notably, the EV uptake was a function of both subtype and differentiation state of donor cells. Thus, while, EVs produced by differentiated MES GSCs were internalized less efficiently than those from undifferentiated cells they exhibited an increased stimulatory potential for human brain endothelial cells. Such stimulating activity was also observed for EVs derived from differentiated PN GSCs, despite their even weaker uptake by endothelial cells. These findings suggest that the role of EVs as biological mediators and biomarkers in GBM may depend on the molecular subtype and functional state of donor cancer cells, including cancer stem cells.

Abbreviations: CryoTEM: cryo-transmission electron microscopy; DIFF: differentiated GSCs; EGF: epidermal growth factor; DUC: differential ultracentrifugation; EV: extracellular vesicle; FGF: fibroblast growth factor; GBM: glioblastoma multiforme; GFAP: glial fibrillary acidic protein; GO: gene ontology; GSC: glioma stem cells; HBEC-5i: human brain endothelial cells; MES: mesenchymal cells; MTS - [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; PMT1: proneural-to-mesenchyman transition cell line 1; PN: proneural cells; TEM: transmission electron microscopy; WB: western blotting

The Impact of Oncogenic EGFRvIII on the Proteome of Extracellular Vesicles Released from Glioblastoma Cells

Glioblastoma multiforme (GBM) is a highly aggressive and heterogeneous form of primary brain tumors, driven by a complex repertoire of oncogenic alterations, including the constitutively active epidermal growth factor receptor (EGFRvIII). EGFRvIII impacts both cell-intrinsic and non-cell autonomous aspects of GBM progression, including cell invasion, angiogenesis and modulation of the tumor microenvironment. This is, at least in part, attributable to the release and intercellular trafficking of extracellular vesicles (EVs), heterogeneous membrane structures containing multiple bioactive macromolecules. Here we analyzed the impact of EGFRvIII on the profile of glioma EVs using isogenic tumor cell lines, in which this oncogene exhibits a strong transforming activity. We observed that EGFRvIII expression alters the expression of EV-regulating genes (vesiculome) and EV properties, including their protein composition. Using mass spectrometry, quantitative proteomic analysis and Gene Ontology terms filters, we observed that EVs released by EGFRvIII-transformed cells were enriched for extracellular exosome and focal adhesion related proteins. Among them, we validated the association of pro-invasive proteins (CD44, BSG, CD151) with EVs of EGFRvIII expressing glioma cells, and downregulation of exosomal markers (CD81 and CD82) relative to EVs of EGFRvIII-negative cells. Nano-flow cytometry revealed that the EV output from individual glioma cell lines was highly heterogeneous, such that only a fraction of vesicles contained specific proteins (including EGFRvIII). Notably, cells expressing EGFRvIII released EVs double positive for CD44/BSG, and these proteins also colocalized in cellular filopodia. We also detected the expression of homophilic adhesion molecules and increased homologous EV uptake by EGFRvIII-positive glioma cells. These results suggest that oncogenic EGFRvIII reprograms the proteome and uptake of GBM-related EVs, a notion with considerable implications for their biological activity and properties relevant for the development of EV-based cancer biomarkers.

Delivery of MGMT mRNA to glioma cells by reactive astrocyte-derived exosomes confers a temozolomide resistance phenotype

The glioma-astrocyte interaction plays an important role in tumor microenvironment remodeling; however, the underlying mechanism has not been completely clarified. In this study, we show that glioma cells stimulate normal human astrocyte (NHA) into reactive astrocyte (RAS) in a non-contact manner. Additionally, the amount of O6-alkylguanine DNA alkyltransferase (MGMT) mRNA in exosomes (EXOs) released by RAS was significantly increased compared with that in non-reactive NHA. Importantly, MGMT-negative glioma cells can take up RAS-EXOs and acquire a temozolomide (TMZ)-resistant phenotype via the translation of exogenous exosomal MGMT mRNA both in vitro and in vivo. Our findings illuminate a novel phenomenon that may be a potent mechanism underlying glioma recurrence in which glioma-associated NHAs protect MGMT-negative glioma cells from TMZ-induced apoptosis by the functional intercellular transfer of exosomal MGMT mRNA.