Brain tumor microvesicles: insights into intercellular communication in the nervous system

Engineered exosome therapeutics for neurodegenerative diseases

An increase in life expectancy comes with a higher risk for age-related neurological and cognitive dysfunctions. Given the psycho-socioeconomic burden due to unhealthy aging in the coming decades, the United Nations has declared 2021-2030 as a decade of healthy aging. In this line, multipotent mesenchymal stromal cell-based therapeutics received special interest from the research community. Based on decades of research on cell therapy, a consensus has emerged that the therapeutic effects of cell therapy are due to the paracrine mechanisms rather than cell replacement. Exosomes, a constituent of the secretome, are nano-sized vesicles that have been a focus of intense research in recent years as a possible therapeutic agent or as a cargo to deliver drugs of interest into the central nervous system to induce neurogenesis, reduce neuroinflammation, confer neuroregeneration/neuroprotection, and improve cognitive and motor functions. In this review, we have discussed the neuroprotective properties of exosomes derived from adult mesenchymal stem cells, with a special focus on the role of exosomal miRNAs. We also reviewed various strategies to improve exosome production and their content for better therapeutic effects. Further, we discussed the utilization of ectomesenchymal stem cells like dental pulp stem cells and their exosomes in treating neurodegenerative diseases.

Pathological Deficit of Cystatin B Impairs Synaptic Plasticity in EPM1 Human Cerebral Organoids

Cystatin B (CSTB) is a small protease inhibitor protein being involved in cell proliferation and neuronal differentiation. Loss-of-function mutations in CSTB gene cause progressive myoclonic epilepsy 1 (EPM1). We previously demonstrated that CSTB is locally synthesized in synaptic nerve terminals from rat brain and secreted into the media, indicating its role in synaptic plasticity. In this work, we have further investigated the involvement of CSTB in synaptic plasticity, using synaptosomes from human cerebral organoids (hCOs) as well as from rodents' brain. Our data demonstrate that CSTB is released from synaptosomes in two ways: (i) as a soluble protein and (ii) in extracellular vesicles-mediated pathway. Synaptosomes isolated from hCOs are enriched in pre-synaptic proteins and contain CSTB at all developmental stages analyzed. CSTB presence in the synaptic territories was also confirmed by immunostaining on human neurons in vitro. To investigate if the depletion of CSTB affects synaptic plasticity, we characterized the synaptosomes from EPM1 hCOs. We found that the levels of presynaptic proteins and of an initiation factor linked to local protein synthesis were both reduced in EPM1 hCOs and that the extracellular vesicles trafficking pathway was impaired. Moreover, EPM1 neurons displayed anomalous morphology with longer and more branched neurites bearing higher number of intersections and nodes, suggesting connectivity alterations. In conclusion, our data strengthen the idea that CSTB plays a critical role in the synapse physiology and reveal that pathologically low levels of CSTB may affect synaptic plasticity, leading to synaptopathy and altered neuronal morphology.

Extracellular Vesicles: A New Approach to Study the Brain's Neural System and Its Diseases

In normal and pathophysiological conditions our cells secrete vesicular bodies known as extracellular particles. Extracellular vesicles are lipid-bound extracellular particles. A majority of these extracellular vesicles are linked to cell-to-cell communication. Brain consists of tightly packed neural cells. Neural cell releases extracellular vesicles in cerebrospinal fluid. Extracellular vesicle mediated crosstalk maintains neural homeostasis in the central nervous system via transferring cargos between neural cells. In neurodegenerative diseases, small extracellular vesicle transfer misfolded proteins to healthy cells in the neural microenvironment. They can also cross blood-brain barrier (BBB) and stimulate peripheral immune response inside central nervous system. In today's world different approaches employ extracellular vesicle in various therapeutics. This review gives a brief knowledge about the biological relevance of extracellular vesicles in the central nervous system and relevant advances in the translational application of EV in brain disorders.

Recent Advancements on the Use of Exosomes as Drug Carriers for the Treatment of Glioblastoma

Glioblastoma (GBM) is the most common and aggressive cancer of the brain. Presently, GBM patients have a poor prognosis, and therapy primarily aims to extend the life expectancy of affected patients. The current treatment of GBM in adult cases and high-grade gliomas in the pediatric population involves a multimodal approach that includes surgical resection followed by simultaneous chemo/radiotherapy. Exosomes are nanoparticles that transport proteins and nucleic acids and play a crucial role in mediating intercellular communication. Recent evidence suggests that these microvesicles may be used as biological carriers and offer significant advantages in targeted therapy. Due to their inherent cell-targeting properties, circulation stability, and biocompatibility, exosomes are emerging as promising new carriers for drugs and biotherapeutics. Furthermore, these nanovesicles are a repository of potential diagnostic and prognostic markers. In this review, we focus on the therapeutic potentials of exosomes in nano-delivery and describe the latest evidence of their use as a therapeutic tool in GBM.

Next-Generation Sequencing Comparative Analysis of DNA Mutations between Blood-Derived Extracellular Vesicles and Matched Cancer Tissue in Patients with Grade 4 Glioblastoma

The biological heterogeneity of glioblastoma, IDH-wildtype (GBM, CNS WHO grade 4), the most aggressive type of brain cancer, is a critical hallmark, caused by changes in the genomic mutational asset and influencing clinical progression over time. The understanding and monitoring of the mutational profile is important not only to reveal novel therapeutic targets in this set of patients, but also to ameliorate the clinical stratification of subjects and the prognostic significance. As neurosurgery represents the primary technique to manage GBM, it is of utmost importance to optimize alternative and less invasive methods to monitor the dynamic mutation profile of these patients. Extracellular vesicles (EVs) are included in the liquid biopsy analysis and have emerged as the biological mirror of escaping and surviving mechanisms by many tumors, including glioblastoma. Very few studies have investigated the technical feasibility to detect and analyze the genomic profile by Next-Generation Sequencing (UMI system) in circulating EVs of patients with grade IV glioblastoma. Here, we attempted to characterize and to compare the corresponding matched tissue samples and potential variants with pathogenic significance of the DNA contained in peripheral-blood-derived EVs. The NGS analysis has revealed that patients with grade IV glioblastoma exhibited lesser DNA content in EVs than controls and that, both in EVs and matched cancer tissues, the NF1 gene was consistently mutated in all patients, with the c.2568C>G as the most common pathogenic variant expressed. This study supports the clinical utility of circulating EVs in glioblastoma as an eligible tool for personalized medicine.

Validation of a CE-IVD, urine exosomal RNA expression assay for risk assessment of prostate cancer prior to biopsy

Improved risk stratification of patients suspected of prostate cancer prior to biopsy continues to be an unmet clinical need. ExoDx Prostate (IntelliScore) “EPI” is a non-invasive urine test utilizing RNA from exosomes to provide a risk score that correlates with the likelihood of finding high grade prostate cancer at biopsy. Here, we present the results from a prospective clinical validation study of EPI-CE, a CE-marked in-vitro diagnostic (IVD) assay, specifically developed for use in European clinical laboratories. The study (NCT04720599) enrolled patients with ≥ 50 years, PSA 2–10 ng/mL, prior to MRI, who were scheduled for initial biopsy. First catch urine samples were collected from participants without prior digital rectal examination or prostate massage. Exosomal RNA was isolated and expression levels of three biomarkers ERG, PCA3 and SPDEF were analyzed according to the EPI-CE Instructions For Use. In the study cohort of N = 109 patients, EPI-CE was validated to have a Negative Predictive Value of 89%, a Sensitivity of 92% and a superior performance to two commonly used multiparametric risk calculators (PCPT and ERSPC) in both Receiver Operating Characteristics with a higher Area Under the Curve for EPI-CE 0.67 (95% CI 0.56–0.77) versus PCPT 0.59 (95% CI 0.47–0.71) and ERSPC 0.60 (95% CI 0.49–0.72) and higher Net Benefits analysis across a wide range of risk acceptance levels. This is the first clinical study reporting on the performance of EPI-CE. We demonstrate that EPI-CE provides information beyond standard clinical parameters and provides a better risk assessment prior to MRI, of patients suspected of prostate cancer, than the commonly used multiparametric risk calculators.

Non-Coding RNAs in Glioma Microenvironment and Angiogenesis

Glioma, especially glioblastoma, is the most common and lethal brain tumor. In line with the complicated vascularization processes and the strong intratumoral heterogeneity, tumor-associated blood vessels in glioma are regulated by multiple types of cells through a variety of molecular mechanisms. Components of the tumor microenvironment, including tumor cells and tumor-associated stromata, produce various types of molecular mediators to regulate glioma angiogenesis. As critical regulatory molecules, non-coding RNAs (ncRNAs) inside cells or secreted to the tumor microenvironment play essential roles in glioma angiogenesis. In this review, we briefly summarize recent studies about the production, delivery, and functions of ncRNAs in the tumor microenvironment, as well as the molecular mechanisms underlying the regulation of angiogenesis by ncRNAs. We also discuss the ncRNA-based therapeutic strategies in the anti-angiogenic therapy for glioma treatment.

Systemic Proteomic Analysis Reveals Distinct Exosomal Protein Profiles in Rheumatoid Arthritis

Objective

Rheumatoid arthritis (RA) is a complex disease with unknown pathogenesis. In recent years, fewer have paid attention to the broad spectrum of systemic markers of RA. The aim of this study was to identify exosomal candidate proteins in the pathogenesis of RA.

Methods

Totally, 12 specimens of plasma from 6 RA patients and 6 age- and gender-matched controls from the Chinese population were obtained for nanoscale liquid chromatography coupled to tandem mass spectrometry (nano-LC-MS/MS) analysis to identify exosomal profiles.

Results

A total of 278 exosomal proteins were detected. Among them, 32 proteins were significantly upregulated (FC ≥ 2.0 and P < 0.05) and 5 proteins were downregulated (FC ≤ 0.5 and P < 0.05). Bioinformatics analysis revealed that transthyretin (TTR), angiotensinogen (AGT), lipopolysaccharide-binding protein (LBP), monocyte differentiation antigen CD14 (CD14), cartilage oligomeric matrix protein (COMP), serum amyloid P (SAP/APCS), and tenascin (TNC) can interact with each other. Subsequently, these cross-linked proteins may be mainly involved in the inflammatory-related pathways to mediate the onset of RA. Noteworthy, the LBP/CD14 complex can promote the expression of IL-8 and TNF-α, eventually leading to the development of RA.

Conclusions

Our findings suggest distinct plasmatic exosomal protein profiles in RA patients. These proteins not only take important parts in the vicious circle in the pathogenic process of RA but also serve as novel biomarkers in RA diagnosis and prognosis.

Exosomes: Small EVs with Large Immunomodulatory Effect in Glioblastoma

Glioblastomas are among the most aggressive tumors, and with low survival rates. They are characterized by the ability to create a highly immunosuppressive tumor microenvironment. Exosomes, small extracellular vesicles (EVs), mediate intercellular communication in the tumor microenvironment by transporting various biomolecules (RNA, DNA, proteins, and lipids), therefore playing a prominent role in tumor proliferation, differentiation, metastasis, and resistance to chemotherapy or radiation. Exosomes are found in all body fluids and can cross the blood-brain barrier due to their nanoscale size. Recent studies have highlighted the multiple influences of tumor-derived exosomes on immune cells. Owing to their structural and functional properties, exosomes can be an important instrument for gaining a better molecular understanding of tumors. Furthermore, they qualify not only as diagnostic and prognostic markers, but also as tools in therapies specifically targeting aggressive tumor cells, like glioblastomas.

Liquid biopsies for the diagnosis and surveillance of primary pediatric central nervous system tumors: a review for practicing neurosurgeons

OBJECTIVE

Primary brain tumors are the most common cause of cancer-related deaths in children and pose difficult questions for the treating physician regarding issues such as the risk/benefit of performing a biopsy, the accuracy of monitoring methods, and the availability of prognostic indicators. It has been recently shown that tumor-specific DNA and proteins can be successfully isolated in liquid biopsies, and it may be possible to exploit this potential as a particularly useful tool for the clinician in addressing these issues.

METHODS

A review of the current literature was conducted by searching PubMed and Scopus. MeSH terms for the search included "liquid biopsy," "brain," "tumor," and "pediatrics" in all fields. Articles were reviewed to identify the type of brain tumor involved, the method of tumor DNA/protein analysis, and the potential clinical utility. All articles involving primary studies of pediatric brain tumors were included, but reviews were excluded.

RESULTS

The successful isolation of circulating tumor DNA (ctDNA), extracellular vesicles, and tumor-specific proteins from liquid biopsies has been consistently demonstrated. This most commonly occurs through CSF analysis, but it has also been successfully demonstrated using plasma and urine samples. Tumor-related gene mutations and alterations in protein expression are identifiable and, in some cases, have been correlated to specific neoplasms. The quantity of ctDNA isolated also appears to have a direct relationship with tumor progression and response to treatment.

CONCLUSIONS

The use of liquid biopsies for the diagnosis and monitoring of primary pediatric brain tumors is a foreseeable possibility, as the requisite developmental steps have largely been demonstrated. Increasingly advanced molecular methods are being developed to improve the identification of tumor subtypes and tumor grades, and they may offer a method for monitoring treatment response. These minimally invasive markers will likely be used in the clinical treatment of pediatric brain tumors in the future.

Role of extracellular vesicles in neurodegenerative diseases

Extracellular vesicles (EVs) are heterogeneous cell-derived membranous structures that arise from the endosome system or directly detach from the plasma membrane. In recent years, many advances have been made in the understanding of the clinical definition and pathogenesis of neurodegenerative diseases, but translation into effective treatments is hampered by several factors. Current research indicates that EVs are involved in the pathology of diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Besides, EVs are also involved in the process of myelin formation, and can also cross the blood-brain barrier to reach the sites of CNS injury. It is suggested that EVs have great potential as a novel therapy for the treatment of neurodegenerative diseases. Here, we reviewed the advances in understanding the role of EVs in neurodegenerative diseases and addressed the critical function of EVs in the CNS. We have also outlined the physiological mechanisms of EVs in myelin regeneration and highlighted the therapeutic potential of EVs in neurodegenerative diseases.

Infrared Nanospectroscopy of Individual Extracellular Microvesicles

Extracellular vesicles are membrane-delimited structures, involved in several inter-cellular communication processes, both physiological and pathological, since they deliver complex biological cargo. Extracellular vesicles have been identified as possible biomarkers of several pathological diseases; thus, their characterization is fundamental in order to gain a deep understanding of their function and of the related processes. Traditional approaches for the characterization of the molecular content of the vesicles require a large quantity of sample, thereby providing an average molecular profile, while their heterogeneity is typically probed by non-optical microscopies that, however, lack the chemical sensitivity to provide information of the molecular cargo. Here, we perform a study of individual microvesicles, a subclass of extracellular vesicles generated by the outward budding of the plasma membrane, released by two cultures of glial cells under different stimuli, by applying a state-of-the-art infrared nanospectroscopy technique based on the coupling of an atomic force microscope and a pulsed laser, which combines the label-free chemical sensitivity of infrared spectroscopy with the nanometric resolution of atomic force microscopy. By correlating topographic, mechanical and spectroscopic information of individual microvesicles, we identified two main populations in both families of vesicles released by the two cell cultures. Subtle differences in terms of nucleic acid content among the two families of vesicles have been found by performing a fitting procedure of the main nucleic acid vibrational peaks in the 1000–1250 cm⁻¹ frequency range.

Exosomal prostate-specific G-protein-coupled receptor induces osteoblast activity to promote the osteoblastic metastasis of prostate cancer

Background

Prostate cancer (PCa) is the second leading cause of cancer-related deaths worldwide. Prostate-specific G-protein-coupled receptor (PSGR) has been identified as a new potential biomarker and therapeutic target for PCa. However, the influence of exosomal PSGR on PCa metastasis remains unknown. This study aimed to identify the regulatory role of exosomal PSGR in the bone microenvironment, prior to metastasis of PCa and the underlying mechanism.

Methods

hFOB1.19 cells were co-cultured with PC-3 exosomes exhibiting PSGR overexpression. Alkaline phosphatase (ALP) and von Kossa staining methods were used to measure the osteogenesis of hFOB1.19 cells. RNA sequencing was used to screen the downstream target genes of PSGR and the signaling pathways involved. The expression of the candidate genes was verified using quantitative real-time polymerase chain reaction (qRT-PCR).

Results

ALP and von Kossa staining results showed that PC-3 exosomes with overexpressed PSGR enhanced osteogenesis of hFOB1.19 cells. A total of 853 mRNAs were differentially expressed in hFOB1.19 cells of the PSGR-overexpressing PC3 cell (PC3^PSGR+ exosome) group compared to the negative exosome control (NC) group, among which 182 mRNAs were significantly upregulated and 671 were downregulated. The functional enrichment and pathway analysis showed that differentially expressed mRNAs were mainly involved in cellular responses to interleukin-1 (IL1), chemotaxis, inflammation, transcriptional misregulation in cancer, and MAKP and NF-κB signaling pathways. qRT-PCR showed that levels of intercellular adhesion molecule-1 (ICAM1), RELB proto-oncogene, NF-κB subunit (RELB), and IL1 beta (IL1B) were significantly decreased in hFOB1.19 cells of the PSGR-overexpression group.

Conclusions

This study suggests that PSGR may regulate the MAKP and NF-κB signaling pathways involved in the process of bony metastases by targeting ICAM1, RELB, and IL1B.

A urine-based Exosomal gene expression test stratifies risk of high-grade prostate Cancer in men with prior negative prostate biopsy undergoing repeat biopsy

Background

Initial prostate biopsy often fails to identify prostate cancer resulting in patient anxiety, especially when clinical features such as prostate specific antigen (PSA) remain elevated, leading to the need for repeat biopsies. Prostate biomarker tests, such as the ExoDx™ Prostate (IntelliScore), or EPI test, have been shown to provide individualized risk assessment of clinically significant prostate cancer at initial biopsy; however, the performance in the repeat biopsy setting is not well established.

Methods

As part of a previous prospective clinical validation study evaluating the performance of the EPI test, we collected first-catch, non-DRE urine samples across 22 sites from men with at least one prior negative biopsy scheduled to undergo a repeat prostate biopsy to rule out prostate cancer. All men were 50 years or older with a PSA 2–10 ng/mL. Exosomal mRNA was extracted and expression of three genomic markers, PCA3, ERG and SPDEF was measured. The resulting EPI score was correlated with biopsy results.

Results

229 men with a prior negative biopsy underwent repeat biopsies. ExoDx Prostate demonstrated good performance ruling out high-grade (Grade group 2, GG2, or higher) prostate cancer (HGPCa) using the previously validated 15.6 cut point in the initial biopsy setting. The EPI test yielded an NPV of 92% independent of other clinical features and would have avoided 26% of unnecessary biopsies while missing only five patients with HGPCa (2.1%). Furthermore, the EPI test provided additional information at a cut-point of 20 and 29.6 with an NPV of 94%, potentially delaying 35 and 61% of unnecessary biopsies, respectively. AUC curves and Net Health Benefit Analyses demonstrated superior performance of ExoDx Prostate over PSA and clinical only risk calculators, i.e. ERSPC.

Conclusions

The EPI test provided good performance using the 15.6 cut-point for ruling out HGPCa / GG2 or higher in men undergoing a repeat prostate biopsy with a PSA of 2–10 ng/ml. Furthermore, the test utilizes gene expression data independent of clinical features to predict the likelihood of HGPCa / GG2 on a subsequent needle biopsy.

Identification of biomarkers associated with extracellular vesicles based on an integrative pan-cancer bioinformatics analysis

Extracellular vesicle (EV) has received increasing attention over the last decade. However, biomarkers and mechanisms underlying remain largely limited. Three microarray profiles, GSE78718 (K562 leukemia cell line), GSE45301 (U87-MG glioblastoma cell line), and GSE9589 (SW480 colon cancer cell line), were analyzed for the overlapped differentially expressed genes (DEGs). SurvExpress was used for the prognostic analysis of hub genes signature. Predicted transcription factors networks were built by NetworkAnalysis. Characterization between hub genes and immune cells was analyzed by the tumor immune estimation resources (TIMER) and single-sample gene set enrichment analysis (ssGSEA). The most significantly enriched pathway was lysosome. Hub genes included lysosomal-associated membrane protein 1 (LAMP1), heat shock protein family A (Hsp70) member 5 (HSPA5), lysosomal-associated membrane protein 2 (LAMP2), integrin subunit alpha V (ITGAV), and transmembrane protein 30A (TMEM30A). Significant prognostic values of hub genes signature were identified in glioblastoma (P-value = 0.006), but not colon cancer. In colon cancer, ITGAV displayed remarkably high correlation with tumor immune infiltrating cells. In glioblastoma, the highest correlation was found between HSPA5 and dendritic cell. Moreover, distinct association of immune cells between cell and EV were identified via ssGSEA. This study identified biomarkers in EV with potential immunological insights and clinical values.

The Emerging Role of Extracellular Vesicles in the Glioma Microenvironment: Biogenesis and Clinical Relevance

Gliomas are a diverse group of brain tumors comprised of malignant cells ('tumor' cells) and non-malignant 'normal' cells, including neural (neurons, glia), inflammatory (microglia, macrophage) and vascular cells. Tumor heterogeneity arises in part because, within the glioma mass, both 'tumor' and 'normal' cells secrete factors that form a unique microenvironment to influence tumor progression. Extracellular vesicles (EVs) are critical mediators of intercellular communication between immediate cellular neighbors and distantly located cells in healthy tissues/organs and in tumors, including gliomas. EVs mediate cell-cell signaling as carriers of nucleic acid, lipid and protein cargo, and their content is unique to cell types and physiological states. EVs secreted by non-malignant neural cells have important physiological roles in the healthy brain, which can be altered or co-opted to promote tumor progression and metastasis, acting in combination with glioma-secreted EVs. The cell-type specificity of EV content means that 'vesiculome' data can potentially be used to trace the cell of origin. EVs may also serve as biomarkers to be exploited for disease diagnosis and to assess therapeutic progress. In this review, we discuss how EVs mediate intercellular communication in glioma, and their potential role as biomarkers and readouts of a therapeutic response.

Extracellular Vesicles in Viral Infections of the Nervous System

Almost all types of cells release extracellular vesicles (EVs) into the extracellular space. EVs such as exosomes and microvesicles are membrane-bound vesicles ranging in size from 30 to 1000 nm in diameter. Under normal conditions, EVs mediate cell to cell as well as inter-organ communication via the shuttling of their cargoes which include RNA, DNA and proteins. Under pathological conditions, however, the number, size and content of EVs are found to be altered and have been shown to play crucial roles in disease progression. Emerging studies have demonstrated that EVs are involved in many aspects of viral infection-mediated neurodegenerative diseases. In the current review, we will describe the interactions between EV biogenesis and the release of virus particles while also reviewing the role of EVs in various viral infections, such as HIV-1, HTLV, Zika, CMV, EBV, Hepatitis B and C, JCV, and HSV-1. We will also discuss the potential uses of EVs and their cargoes as biomarkers and therapeutic vehicles for viral infections.

Large and small extracellular vesicles released by glioma cells in vitro and in vivo

Tumour cells release diverse populations of extracellular vesicles (EVs) ranging in size, molecular cargo, and function. We sought to characterize mRNA and protein content of EV subpopulations released by human glioblastoma (GBM) cells expressing a mutant form of epidermal growth factor receptor (U87EGFRvIII) in vitro and in vivo with respect to size, morphology and the presence of tumour cargo. The two EV subpopulations purified from GBM U87EGFRvIII cancer cells, non-cancer human umbilical vein endothelial cells (HUVEC; control) and serum of U87EGFRvIII glioma-bearing mice using differential centrifugation (EVs that sediment at 10,000 × g or 100,000 × g are termed large EVs and small EVs, respectively) were characterized using transmission electron microscopy (TEM), confocal microscopy, nanoparticle tracking analysis (NTA), flow cytometry, immunofluorescence (IF), quantitative-polymerase chain reaction (qPCR), droplet digital polymerase chain reaction (ddPCR) and micro-nuclear magnetic resonance (μNMR). We report that both U87EGFRvIII and HUVEC release a similar number of small EVs, but U87EGFRvIII glioma cells alone release a higher number of large EVs compared to non-cancer HUVEC. The EGFRvIII mRNA from the two EV subpopulations from U87EGFRvIII glioma cells was comparable, while the EGFR protein (wild type + vIII) levels are significantly higher in large EVs. Similarly, EGFRvIII mRNA in large and small EVs isolated from the serum of U87EGFRvIII glioma-bearing mice is comparable, while the EGFR protein (wild type + vIII) levels are significantly higher in large EVs. Here we report for the first time a direct comparison of large and small EVs released by glioma U87EGFRvIII cells and from serum of U87EGFRvIII glioma-bearing mice. Both large and small EVs contain tumour-specific EGFRvIII mRNA and proteins and combining these platforms may be beneficial in detecting rare mutant events in circulating biofluids.

Emerging Roles of Long Non-Coding RNAs as Drivers of Brain Evolution

Mammalian genomes encode tens of thousands of long-noncoding RNAs (lncRNAs), which are capable of interactions with DNA, RNA and protein molecules, thereby enabling a variety of transcriptional and post-transcriptional regulatory activities. Strikingly, about 40% of lncRNAs are expressed specifically in the brain with precisely regulated temporal and spatial expression patterns. In stark contrast to the highly conserved repertoire of protein-coding genes, thousands of lncRNAs have newly appeared during primate nervous system evolution with hundreds of human-specific lncRNAs. Their evolvable nature and the myriad of potential functions make lncRNAs ideal candidates for drivers of human brain evolution. The human brain displays the largest relative volume of any animal species and the most remarkable cognitive abilities. In addition to brain size, structural reorganization and adaptive changes represent crucial hallmarks of human brain evolution. lncRNAs are increasingly reported to be involved in neurodevelopmental processes suggested to underlie human brain evolution, including proliferation, neurite outgrowth and synaptogenesis, as well as in neuroplasticity. Hence, evolutionary human brain adaptations are proposed to be essentially driven by lncRNAs, which will be discussed in this review.

Differential proteomic analysis of serum exosomes reveals alterations in progression of Parkinson disease

Exosomes are nanometer-sized vesicles with intercellular communication functions, and their encapsulated proteins may participate in the pathological process of neurodegenerative disorders. The aim of this study was to identify the protein changes of serum exosomes in Parkinson disease (PD) patients with different disease progress types, and to identify potential biomarkers. The exosomes of PD patients with different severity and healthy control group were isolated from serum. The exosome proteins were analyzed by mass spectrometry with label-free quantitative proteomics. A total of 429 proteins were identified, of which 14 were significantly different in mild and severe PD patients. The expression levels of 7 proteins, including pigmented epithelium-derived factor, afamin, apolipoprotein D and J, were significantly increased in PD patients. The expression levels of 7 proteins, including complement C1q and protein Immunoglobulin Lambda Variable 1-33 (IGLV1-33)Cluster -33, were decreased in PD patients. These differentially expressed proteins were analyzed by gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis, which confirmed that the interaction between prion diseases and ECM receptors was the most significant pathways of enrichment. The changes of proteins and pathways may be related to the pathophysiological mechanism of PD. Therefore, some of these proteins could be considered as potential biomarkers for early PD diagnosis.

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.

Exosomes and their implications in central nervous system tumor biology

Exosomes are 20-100 nm cellular derived vesicles that upon discovery, were thought to be a form of cellular recycling of intracellular contents. More recently, these vesicles are under investigation for their purported significant roles in intercellular communication in both healthy and diseased states. Herein, we focus on the secretion of exosomes associated with glioblastoma, as most exosome studies on brain tumors have been performed in this tumor type. However, we included exosomes secreted from other forms of brain tumors for comparison as available. Exosomes contain intracellular content that can be transferred to other cells in the tumor or to cells of the immune system and endothelial cells. These recipient cells may subsequently take on oncogenic properties, including therapeutic resistance, cancer progression, and angiogenesis. Genetic components (DNA, RNA and miRNA) of the cell of origin may be included in the secreted exosomes. The presence of genetic material in the exosomes could serve as a biomarker for mutations in tumors, potentially leading to novel treatment strategies. In the last decade, exosomes have been identified as having a major impact on multiple aspects of medicine and tumor biology, and appear to be primed for a critical position in cancer diagnosis, prognosis, and treatment.

Genomic biomarkers in prostate cancer

Prostate cancer is the most common non-cutaneous cancer among men in the United States. In the last decade there has been a rapid expansion in the field of biomarker assays for diagnosis, prognosis, and treatment prediction in prostate cancer. The evidence base for these assays is rapidly evolving. With several commercial assays available at each stage of the disease, deciding which genomic assays are appropriate for which patients can be nuanced for physicians. In an effort to help guide these decisions in clinical practice, we aim to give an update on the current status of the biomarker field of prostate cancer.

Regulation and mechanisms of extracellular vesicle biogenesis and secretion

EV (extracellular vesicle) biology is a rapidly expanding field. These heterogeneous membrane vesicles, which are shed from virtually all cell types, collectively represent a new dimension of intercellular communication in normal physiology and disease. They have been shown to deliver infectious and pathogenic agents to non-infected cells whereas in cancers they are thought to condition the tumor microenvironment. Their presence in body fluids and inherent capacity for systemic delivery point to their clinical promise. All of the above only intensifies the need to better understand the classification, mode of biogenesis, and contents of the different subtypes of EVs. This article focusses on vesicle subtypes labeled as exosomes and MVs (microvesicles) and discusses the biogenesis and release of these vesicles from cells.

Cardiac-specific delivery by cardiac tissue-targeting peptide-expressing exosomes

Naturally occurring RNA carriers such as exosomes might be an untapped source of effective delivery vehicles. However, if exosomes are to be exploited for therapeutic applications, they must target specific tissues or cell types to avoid off-target effects. This study evaluated whether genetic modification of exosomes could enhance exosome delivery to heart cells and heart tissue without toxicity. Exosomes expressing cardiac-targeting peptide (CTP)-Lamp2b on the exosomal membrane (CTP-Exo) were generated by introducing vectors encoding CTP-Lamp2b into HEK 293 cells. The expression of CTP-Lamp2b peptide on exosomes was stabilized by attaching glycosylation sequences. Exosomes expressing only Lamp2b on exosomal membranes (CTL-Exo) were generated as a control. The in vitro and in vivo uptake of CTL-Exo and CTP-Exo was evaluated in cell lines and mice. Both exosomes were delivered to HEK 293 and H9C2 cells. The delivery of the exosome was not different between CTP-Exo and CTL-Exo in HEK 293 cells, whereas the delivery of CTP-Exo was 16% greater than that of CTL-Exo in H9C2 cells (P = 0.047). Cell viability was maintained at almost 100% with different dosages of both CTL-Exo and CTP-Exo. Moreover, compared with CTL-Exo, the in vivo delivery of exosomes to the hearts of mice was increased by 15% with CTP-Exo (P = 0.035). The delivery to livers and spleens was not different between the two exosomes. Genetic modification of exosomes by expressing CTP-Lamp2b on the exosomal membrane enhanced exosome delivery to heart cells and the heart tissue. These results suggested that CTP-Exo might be used as a therapeutic tool for heart disease.

Molecular Determinants of Malignant Brain Cancers: From Intracellular Alterations to Invasion Mediated by Extracellular Vesicles

Malignant glioma cells invade the surrounding brain parenchyma, by migrating along the blood vessels, thus promoting cancer growth. The biological bases of these activities are grounded in profound alterations of the metabolism and the structural organization of the cells, which consequently acquire the ability to modify the surrounding microenvironment, by altering the extracellular matrix and affecting the properties of the other cells present in the brain, such as normal glial-, endothelial- and immune-cells. Most of the effects on the surrounding environment are probably exerted through the release of a variety of extracellular vesicles (EVs), which contain many different classes of molecules, from genetic material to defined species of lipids and enzymes. EV-associated molecules can be either released into the extracellular matrix (ECM) and/or transferred to neighboring cells: as a consequence, both deep modifications of the recipient cell phenotype and digestion of ECM components are obtained, thus causing cancer propagation, as well as a general brain dysfunction. In this review, we first analyze the main intracellular and extracellular transformations required for glioma cell invasion into the brain parenchyma; then we discuss how these events may be attributed, at least in part, to EVs that, like the pawns of a dramatic chess game with cancer, open the way to the tumor cells themselves.

Long non-coding RNA HOTAIR enhances angiogenesis by induction of VEGFA expression in glioma cells and transmission to endothelial cells via glioma cell derived-extracellular vesicles

Gliomas are one the most prevalent malignant carcinomas of the central nervous system, and angiogenesis plays a critical role in the progression of these blood vessel-rich tumors. HOTAIR, a long non-coding RNA (lncRNA), acts as an oncogene in gliomas; however, its role in glioma angiogenesis remains unclear. In the present study, we identified a pro-angiogenic activity of HOTAIR. Silencing HOTAIR inhibited glioma-induced endothelial cell proliferation, migration, and tube formation. Further studies showed that vascular endothelial growth factor A (VEGFA) was involved in the HOTAIR-induced glioma angiogenesis. Our study also showed that HOTAIR was present in the glioma cell culture supernatant and was protected by membranes, suggesting that HOTAIR may affect glioma angiogenesis not only via regulation of VEGFA expression in the glioma cells, but also by transmission into endothelial cells via glioma cell-derived extracellular vesicles.

miRNA in Circulating Microvesicles as Biomarkers for Age-Related Cognitive Decline

Community dwelling older individuals from the North Florida region were examined for health status and a comprehensive neuropsychological battery, including the Montreal Cognitive Assessment (MoCA), was performed on each participant. A subpopulation (58 females and 39 males) met the criteria for age (60–89) and no evidence of mild cognitive impairment, with a MoCA score ≥23. Despite the stringent criteria for participation, MoCA scores were negatively correlated within the limited age range. Extracellular microvesicles were isolated from the plasma and samples were found to be positive for the exosome marker CD63, with an enrichment of particles within the size range for exosomes. miRNA was extracted and examined using next generation sequencing with a stringent criterion (average of ≥10 counts per million reads) resulting in 117 miRNA for subsequent analysis. Characterization of expression confirmed pervious work concerning the relative abundance and overall pattern of expression of miRNA in plasma. Correlation analysis indicated that most of the miRNAs (74 miRNAs) were positively correlated with age (p <0.01). Multiple regression was employed to identify the relationship of miRNA expression and MoCA score, accounting for age. MoCA scores were negatively correlated with 13 miRNAs. The pattern of expression for cognition-related miRNA did not match that previously described for Alzheimer’s disease. Enrichment analysis was employed to identify miRNA–gene interactions to reveal possible links to brain function.

Perspective Insights of Exosomes in Neurodegenerative Diseases: A Critical Appraisal

Exosomes are small membranous entities of endocytic origin. Their production by a wide variety of cells in eukaryotes implicates their roles in the execution of essential processes, especially cellular communication. Exosomes are secreted under both physiological and pathophysiological conditions, and their actions on neighboring and distant cells lead to the modulations of cellular behaviors. They also assist in the delivery of disease causing entities, such as prions, α-syn, and tau, and thus, facilitate spread to non-effected regions and accelerate the progressions of neurodegenerative diseases. The characterization of exosomes, provides information on aberrant processes, and thus, exosome analysis has many clinical applications. Because they are associated with the transport of different cellular entities across the blood-brain barrier (BBB), exosomes might be useful for delivering drugs and other therapeutic molecules to brain. Herein, we review roles played by exosomes in different neurodegenerative diseases, and the possibilities of using them as diagnostic biomarkers of disease progression, drug delivery vehicles and in gene therapy.

Application of liquid biopsy in precision medicine: opportunities and challenges

Precision medicine for cancer patients aims to adopt the most suitable treatment options during diagnosis and treatment of individuals. Detecting circulating tumor cell (CTC) or circulating tumor DNA (ctDNA) in plasma or serum could serve as liquid biopsy, which would be useful for numerous diagnostic applications. Liquid biopsies can help clinicians screen and detect cancer early, stratify patients to the most suitable treatment and real-time monitoring of treatment response and resistance mechanisms in the tumor, evaluate the risk for metastatic relapse, and estimate prognosis.We summarized the advantages and disadvantages of tissue and liquid biopsies.We also further compared and analyzed the advantages and limitations of detecting CTCs, ctDNAs, and exosomes. Furthermore, we reviewed the literature related with the application of serum or plasma CTCs, ctDNAs, and exosomes for diagnosis and prognosis of cancer.We also analyzed their opportunities and challenges as future biomarkers. In the future, liquid biopsies could be used to guide cancer treatment. They could also provide the ideal scheme to personalize treatment in precision medicine.

Extracellular Vesicles: Satellites of Information Transfer in Cancer and Stem Cell Biology

The generation and shedding of extracellular vesicles (EVs), including exosomes and microvesicles (MVs), by cells has emerged as a form of intercellular communication with important roles in several physiological processes and diseases such as cancer. These membrane-enclosed packets can transfer specific proteins, RNA transcripts, microRNAs, and even DNA to target cells, thereby altering their function. Despite the exponential growth of the EV field, a great deal remains unclear about the mechanisms that regulate exosome and MV biogenesis, as well as about how to isolate different classes of EVs and how to best take advantage of them for clinical applications.

Cell-based therapy using miR-302-367 expressing cells represses glioblastoma growth

Glioblastomas are incurable primary brain tumors that affect patients of all ages. The aggressiveness of this cancer has been attributed in part to the persistence of treatment-resistant glioblastoma stem-like cells. We have previously discovered the tumor-suppressor properties of the microRNA cluster miR-302-367, representing a potential treatment for glioblastoma. Here, we attempted to develop a cell-based therapy by taking advantage of the capability of glioma cells to secrete exosomes that enclose small RNA molecules. We engineered primary glioma cells to stably express the miR-302-367. Remarkably, these cells altered, in a paracrine-dependent manner, the expression of stemness markers, the proliferation and the tumorigenicity of neighboring glioblastoma cells. Further characterization of the secretome derived from miR-302-367 expressing cells showed that a large amount of miR-302-367 was enclosed in exosomes, which were internalized by the neighboring glioblastoma cells. This miR-302-367 cell-to-cell transfer resulted in the inhibition of its targets such as CXCR4/SDF1, SHH, cyclin D, cyclin A and E2F1. Orthotopic xenograft of miR-302-367-expressing cells together with glioblastoma stem-like cells efficiently altered the tumor development in mice brain.

Comparison of microRNA expression profiles in K562-cells-derived microvesicles and parental cells, and analysis of their roles in leukemia

Microvesicles (MVs) are 30-1,000-nm extracellular vesicles that are released from a multitude of cell types and perform diverse cellular functions, including intercellular communication, antigen presentation, and transfer of proteins, messenger RNA and microRNA (also known as miR). MicroRNAs have been demonstrated to be aberrantly expressed in leukemia, and the overall microRNA expression profile may differentiate normal blood cells vs. leukemia cells. MVs containing microRNAs may enable intercellular cross-talk in vivo. This prompted us to investigate specific variations of microRNA expression patterns in MVs derived from leukemia cells. The present study examined the microRNA expression profile of MVs from chronic myeloid leukemia K562 cells and that of MVs from normal human volunteers' peripheral blood cells. The potential targets of the differentially expressed microRNAs were predicted using computational searches. Bioinformatic analyses of the predicted target genes were performed for further evaluation. The present study analyzed microRNAs of MVs derived from leukemia and normal cells, and characterized specific microRNAs expression. The results revealed that MVs derived from K562 cells expressed 181 microRNAs of the 888 microRNAs assessed. Further analysis revealed that 16 microRNAs were downregulated, while 7 were upregulated in these MVs. In addition, significant differences in microRNA expression profiles between MVs derived from K562 cells and K562 cells were identified. The present results revealed that 77 and 122 microRNAs were only expressed in MVs derived from K562 cells and in K562 cells, respectively. There were 104 microRNAs co-expressed in MVs derived from K562 cells and in K562 cells. Target gene-related pathway analyses demonstrated that the majority of the dysregulated microRNAs were involved in pathways associated with leukemia, particularly the mitogen-activated protein kinase (MAPK) and the p53 signaling pathways. By further conducting microRNA gene network analysis, the present study revealed that the miR-15a/b, miR-16, miR-17 and miR-30 families were likely to play a role in the regulation of the MAPK signaling pathway. Since K562 cells presented the t(9;22) translocation, the current study further examined the predicted function of 12 microRNAs located in chromosomes 9 [Homo sapiens (hsa)-let-7a, hsa-let-7f, miR-126, miR-126*, miR-23b, miR-24, miR-27b and miR-7] and 22 (hsa-let-7b, miR-1249, miR-130b and miR-185), which were expressed both in MVs derived from K562 cells and in K562 cells. The present study identified microRNAs of MVs from leukemia and normal cells, and characterized the expression of specific microRNAs. The current study is also the first to identify and characterize distinct microRNA expression between MVs derived from K562 cells and K562 cells. These findings highlight that a number of microRNAs from leukemia-derived MVs may contribute to the development of hematopoietic malignancies. Further investigation may reveal the function of these differentially expressed microRNAs and may provide potential targets for novel therapeutic strategies.

HIV-1 Viral Protein R Activates NLRP3 Inflammasome in Microglia: implications for HIV-1 Associated Neuroinflammation

Human Immunodeficiency virus (HIV) enters the brain soon after seroconversion and induces chronic neuroinflammation by infecting and activating brain macrophages. Inflammasomes are cytosolic protein complexes that mediate caspase-1 activation and ensuing cleavage and release of IL-1β and -18 by macrophages. Our group recently showed that HIV-1 infection of human microglia induced inflammasome activation in NLRP3-dependent manner. The HIV-1 viral protein R (Vpr) is an accessory protein that is released from HIV-infected cells, although its effects on neuroinflammation are undefined. Infection of human microglia with Vpr-deficient HIV-1 resulted in reduced caspase-1 activation and IL-1β production, compared to cells infected with a Vpr-encoding HIV-1 virus. Vpr was detected at low nanomolar concentrations in cerebrospinal fluid from HIV-infected patients and in supernatants from HIV-infected primary human microglia. Exposure of human macrophages to Vpr caused caspase-1 cleavage and IL-1β release with reduced cell viability, which was dependent on NLRP3 expression. Increased NLRP3, caspase-1, and IL-1β expression was evident in HIV-1 Vpr transgenic mice compared to wild-type littermates, following systemic immune stimulation. Treatment with the caspase-1 inhibitor, VX-765, suppressed NLRP3 expression with reduced IL-1β expression and associated neuroinflammation. Neurobehavioral deficits showed improvement in Vpr transgenic animals treated with VX-765. Thus, Vpr-induced NLRP3 inflammasome activation, which contributed to neuroinflammation and was abrogated by caspase-1 inhibition. This study provides a new therapeutic perspective for HIV-associated neuropsychiatric disease.

From glioblastoma to endothelial cells through extracellular vesicles: messages for angiogenesis

Glioblastoma has one of the highest mortality rates among cancers, and it is the most common and malignant form of brain cancer. Among the typical features of glioblastoma tumors, there is an aberrant vascularization: all gliomas are among the most vascularized/angiogenic tumors. In recent years, it has become clear that glioblastoma cells can secrete extracellular vesicles which are spherical and membrane-enclosed particles released, in vitro or in vivo, by both normal and tumor cells; they are involved in the regulation of both physiological and pathological processes; among the latter, cancer is the most widely studied. Extracellular vesicles from tumor cells convey messages to other tumor cells, but also to normal stromal cells in order to create a microenvironment that supports cancer growth and progression and are implicated in drug resistance, escape from immunosurveillance and from apoptosis, as well as in metastasis formation; they are also involved in angiogenesis stimulation, inducing endothelial cells proliferation, and other pro-angiogenic activities. To this aim, the present paper assesses in detail the extracellular vesicles phenomenon in the human glioblastoma cell line U251 and evaluates extracellular vesicles ability to promote the processes required to achieve the formation of new blood vessels in human brain microvascular endothelial cells, highlighting that they stimulate proliferation, motility, and tube formation in a dose-response manner. Moreover, a molecular characterization shows that extracellular vesicles are fully equipped for angiogenesis stimulation in terms of proteolytic enzymes (gelatinases and plasminogen activators), pro-angiogenic growth factors (VEGF and TGFβ), and the promoting-angiogenic CXCR4 chemokine receptor.

Extracellular vesicles and intercellular communication within the nervous system

Extracellular vesicles (EVs, including exosomes) are implicated in many aspects of nervous system development and function, including regulation of synaptic communication, synaptic strength, and nerve regeneration. They mediate the transfer of packets of information in the form of nonsecreted proteins and DNA/RNA protected within a membrane compartment. EVs are essential for the packaging and transport of many cell-fate proteins during development as well as many neurotoxic misfolded proteins during pathogenesis. This form of communication provides another dimension of cellular crosstalk, with the ability to assemble a "kit" of directional instructions made up of different molecular entities and address it to specific recipient cells. This multidimensional form of communication has special significance in the nervous system. How EVs help to orchestrate the wiring of the brain while allowing for plasticity associated with learning and memory and contribute to regeneration and degeneration are all under investigation. Because they carry specific disease-related RNAs and proteins, practical applications of EVs include potential uses as biomarkers and therapeutics. This Review describes our current understanding of EVs and serves as a springboard for future advances, which may reveal new important mechanisms by which EVs in coordinate brain and body function and dysfunction.

Extracellular Vesicles in Brain Tumor Progression

Brain tumors can be viewed as multicellular 'ecosystems' with increasingly recognized cellular complexity and systemic impact. While the emerging diversity of malignant disease entities affecting brain tissues is often described in reference to their signature alterations within the cellular genome and epigenome, arguably these cell-intrinsic changes can be regarded as hardwired adaptations to a variety of cell-extrinsic microenvironmental circumstances. Conversely, oncogenic events influence the microenvironment through their impact on the cellular secretome, including emission of membranous structures known as extracellular vesicles (EVs). EVs serve as unique carriers of bioactive lipids, secretable and non-secretable proteins, mRNA, non-coding RNA, and DNA and constitute pathway(s) of extracellular exit of molecules into the intercellular space, biofluids, and blood. EVs are also highly heterogeneous as reflected in their nomenclature (exosomes, microvesicles, microparticles) attempting to capture their diverse origin, as well as structural, molecular, and functional properties. While EVs may act as a mechanism of molecular expulsion, their non-random uptake by heterologous cellular recipients defines their unique roles in the intercellular communication, horizontal molecular transfer, and biological activity. In the central nervous system, EVs have been implicated as mediators of homeostasis and repair, while in cancer they may act as regulators of cell growth, clonogenicity, angiogenesis, thrombosis, and reciprocal tumor-stromal interactions. EVs produced by specific brain tumor cell types may contain the corresponding oncogenic drivers, such as epidermal growth factor receptor variant III (EGFRvIII) in glioblastoma (and hence are often referred to as 'oncosomes'). Through this mechanism, mutant oncoproteins and nucleic acids may be transferred horizontally between cellular populations altering their individual and collective phenotypes. Oncogenic pathways also impact the emission rates, types, cargo, and biogenesis of EVs, as reflected by preliminary analyses pointing to differences in profiles of EV-regulating genes (vesiculome) between molecular subtypes of glioblastoma, and in other brain tumors. Molecular regulators of vesiculation can also act as oncogenes. These intimate connections suggest the context-specific roles of different EV subsets in the progression of specific brain tumors. Advanced efforts are underway to capture these events through the use of EVs circulating in biofluids as biomarker reservoirs and to guide diagnostic and therapeutic decisions.

Extracellular Vesicles and MicroRNAs: Their Role in Tumorigenicity and Therapy for Brain Tumors

MicroRNAs are small non-coding RNAs which mediate post-transcriptional gene regulation. Recently, microRNAs have also been found to be localized to the extracellular space, often encapsulated in secreted extracellular vesicles (EVs). This tandem of EVs and tissue-specific expressed/secreted microRNAs that can be taken up by neighboring or distant recipient cells, leading to changes in gene expression-suggests a cell-specialized role in physiological and pathological conditions. The complexity of solid tumors and their distinct pathophysiology relies on interactive communications between the various cell types in the neoplasm (tumor, endothelial, or macrophages, for instance). Understanding how such EV/microRNA-mediated communication occurs may actually lead to avenues for therapeutic exploitation and/or intervention, particularly for the most formidable cancers, such as those in the brain. In this review, the role of microRNAs/EVs in brain tumors will be discussed with emphasis on how these molecules could be utilized for tumor therapy.

Glutaminase-containing microvesicles from HIV-1-infected macrophages and immune-activated microglia induce neurotoxicity

BACKGROUND

HIV-1-infected and/or immune-activated microglia and macrophages are pivotal in the pathogenesis of HIV-1-associated neurocognitive disorders (HAND). Glutaminase, a metabolic enzyme that facilitates glutamate generation, is upregulated and may play a pathogenic role in HAND. Our previous studies have demonstrated that glutaminase is released to the extracellular fluid during HIV-1 infection and neuroinflammation. However, key molecular mechanisms that regulate glutaminase release remain unknown. Recent advances in understanding intercellular trafficking have identified microvesicles (MVs) as a novel means of shedding cellular contents. We posit that during HIV-1 infection and immune activation, microvesicles may mediate glutaminase release, generating excessive and neurotoxic levels of glutamate.

RESULTS

MVs isolated through differential centrifugation from cell-free supernatants of monocyte-derived macrophages (MDM) and BV2 microglia cell lines were first confirmed in electron microscopy and immunoblotting. As expected, we found elevated number of MVs, glutaminase immunoreactivities, as well as glutaminase enzyme activity in the supernatants of HIV-1 infected MDM and lipopolysaccharide (LPS)-activated microglia when compared with controls. The elevated glutaminase was blocked by GW4869, a neutral sphingomyelinase inhibitor known to inhibit MVs release, suggesting a critical role of MVs in mediating glutaminase release. More importantly, MVs from HIV-1-infected MDM and LPS-activated microglia induced significant neuronal injury in rat cortical neuron cultures. The MV neurotoxicity was blocked by a glutaminase inhibitor or GW4869, suggesting that the neurotoxic potential of HIV-1-infected MDM and LPS-activated microglia is dependent on the glutaminase-containing MVs.

CONCLUSIONS

These findings support MVs as a potential pathway/mechanism of excessive glutamate generation and neurotoxicity in HAND and therefore MVs may serve as a novel therapeutic target.

Extracellular Membrane Vesicles as Vehicles for Brain Cell-to-Cell Interactions in Physiological as well as Pathological Conditions

Extracellular vesicles are involved in a great variety of physiological events occurring in the nervous system, such as cross talk among neurons and glial cells in synapse development and function, integrated neuronal plasticity, neuronal-glial metabolic exchanges, and synthesis and dynamic renewal of myelin. Many of these EV-mediated processes depend on the exchange of proteins, mRNAs, and noncoding RNAs, including miRNAs, which occurs among glial and neuronal cells. In addition, production and exchange of EVs can be modified under pathological conditions, such as brain cancer and neurodegeneration. Like other cancer cells, brain tumours can use EVs to secrete factors, which allow escaping from immune surveillance, and to transfer molecules into the surrounding cells, thus transforming their phenotype. Moreover, EVs can function as a way to discard material dangerous to cancer cells, such as differentiation-inducing proteins, and even drugs. Intriguingly, EVs seem to be also involved in spreading through the brain of aggregated proteins, such as prions and aggregated tau protein. Finally, EVs can carry useful biomarkers for the early diagnosis of diseases. Herein we summarize possible roles of EVs in brain physiological functions and discuss their involvement in the horizontal spreading, from cell to cell, of both cancer and neurodegenerative pathologies.

A molecular signature of PCA3 and ERG exosomal RNA from non-DRE urine is predictive of initial prostate biopsy result

BACKGROUND

New screening methods that can add predictive diagnostic value for aggressive (high-grade, Gleason score ⩾ 7) prostate cancer (PCa) are needed to reduce unnecessary biopsies for patients with non-aggressive PCa. This is particularly important for men presenting for an initial biopsy with an equivocal PSA in the 2-10 ng ml(-1) range. PCA3 and ERG are biomarkers that can add predictive value for PCa in urine; however, with a limited utility as a digital rectal exam (DRE) is required.

METHODS

First-catch urine samples were collected at six sites from men scheduled to undergo a prostate biopsy. Exosomal RNA was extracted, RNA copy numbers of ERG and PCA3 were measured by reverse transcription-quantitative PCR (RT-qPCR), and the EXO106 score (the sum of normalized PCA3 and ERG RNA levels) was computed. Performance was compared with standard of care (SOC; PSA, age, race or family history) parameters. Contingency table, logistic regression, receiver operating characteristics curve and box-plot analyses were performed.

RESULTS

In this cohort (N=195), a dichotomous EXO106 score demonstrated good clinical performance in predicting biopsy result for both any cancer and high-grade disease. For high-grade disease, the negative and positive predictive values were 97.5% and 34.5%, respectively. The discrimination between high-grade and Gleason score ⩽ 6 (including benign) biopsy results by a combination of EXO106 and SOC (area under the curve (AUC)=0.803) was significantly improved compared with SOC without EXO106 (AUC=0.6723, P=0.0009). The median EXO106 score correlated (P<0.001; Spearman's rank order) with histologic grade.

CONCLUSIONS

A novel molecular signature (EXO106 score) derived from non-DRE urine demonstrated independent, negative predictive value for the diagnosis of high-grade PCa from initial biopsy for men with 'gray zone' serum PSA levels. Its use in the biopsy decision process could result in fewer prostate biopsies for clinically insignificant disease.

The RNA-centred view of the synapse: non-coding RNAs and synaptic plasticity

If mRNAs were the only RNAs made by a neuron, there would be a simple mapping of mRNAs to proteins. However, microRNAs and other non-coding RNAs (ncRNAs; endo-siRNAs, piRNAs, BC1, BC200, antisense and long ncRNAs, repeat-related transcripts, etc.) regulate mRNAs via effects on protein translation as well as transcriptional and epigenetic mechanisms. Not only are genes ON or OFF, but their ability to be translated can be turned ON or OFF at the level of synapses, supporting an enormous increase in information capacity. Here, I review evidence that ncRNAs are expressed pervasively within dendrites in mammalian brain; that some are activity-dependent and highly enriched near synapses; and that synaptic ncRNAs participate in plasticity responses including learning and memory. Ultimately, ncRNAs can be viewed as the post-it notes of the neuron. They have no literal meaning of their own, but derive their functions from where (and to what) they are stuck. This may explain, in part, why ncRNAs differ so dramatically from protein-coding genes, both in terms of the usual indicators of functionality and in terms of evolutionary constraints. ncRNAs do not appear to be direct mediators of synaptic transmission in the manner of neurotransmitters or receptors, yet they orchestrate synaptic plasticity—and may drive species-specific changes in cognition.

On-chip immunoelectrophoresis of extracellular vesicles released from human breast cancer cells

Extracellular vesicles (EVs) including exosomes and microvesicles have attracted considerable attention in the fields of cell biology and medicine. For a better understanding of EVs and further exploration of their applications, the development of analytical methods for biological nanovesicles has been required. In particular, considering the heterogeneity of EVs, methods capable of measuring individual vesicles are desired. Here, we report that on-chip immunoelectrophoresis can provide a useful method for the differential protein expression profiling of individual EVs. Electrophoresis experiments were performed on EVs collected from the culture supernatant of MDA-MB-231 human breast cancer cells using a measurement platform comprising a microcapillary electrophoresis chip and a laser dark-field microimaging system. The zeta potential distribution of EVs that reacted with an anti-human CD63 (exosome and microvesicle marker) antibody showed a marked positive shift as compared with that for the normal immunoglobulin G (IgG) isotype control. Thus, on-chip immunoelectrophoresis could sensitively detect the over-expression of CD63 glycoproteins on EVs. Moreover, to explore the applicability of on-chip immunoelectrophoresis to cancer diagnosis, EVs collected from the blood of a mouse tumor model were analyzed by this method. By comparing the zeta potential distributions of EVs after their immunochemical reaction with normal IgG, and the anti-human CD63 and anti-human CD44 (cancer stem cell marker) antibodies, EVs of tumor origin circulating in blood were differentially detected in the real sample. The result indicates that the present method is potentially applicable to liquid biopsy, a promising approach to the low-invasive diagnosis of cancer.

Highly-purified exosomes and shed microvesicles isolated from the human colon cancer cell line LIM1863 by sequential centrifugal ultrafiltration are biochemically and functionally distinct

Secretion and exchange of extracellular vesicles (EVs) by most cell types is emerging as a fundamental biological process. Although much is known about EVs, there is still a lack of definition as to how many naturally occurring EV subtypes there are and how their properties and functionalities might differ. This vexing issue is critical if EVs are to be fully harnessed for therapeutic applications. To address this question we have developed and describe here a sequential centrifugal ultrafiltration (SCUF) method to examine, in an unbiased manner, what EV subtypes are released in vitro into cell culture medium using the human colon carcinoma cell line LIM1863 as a model system. Using the culture medium from ∼7.2×10(9) LIM1863 cells, SCUF was performed using hydrophilic PVDF membranes with low protein binding properties (Millipore Durapore™ Ultrafree-CL filters with 0.1, 0.22, 0.45 and 0.65 μm pore size). EV particle sizing was measured using both dynamic light scattering and cryo-electron microscopy. Comparative proteome profiling was performed by GeLC-MS/MS and qualitative protein differences between EV subtypes determined by label-free spectral counting. The results showed essentially two EV subtypes; one subtype (fraction Fn1) comprised heterogeneous EVs with particle diameters of 30-1300 nm, the other (fraction Fn5) being homogeneous EVs of 30-100 nm diameter; based on cryo-EM both EV subtypes were round shaped. Western blot analysis showed Fn5 (SCUF-Exos) contained traditional exosome marker proteins (Alix(+), TSG101(+), CD81(+), CD63(+)), while Fn1 (SCUF-sMVs) lacked these protein markers. These findings were consistent with sMVs isolated by differential centrifugation (10,000 g, DC-sMVs) and exosomes (100,000 g EVs depleted of 10,000 g material). The buoyant density of sMVs determined by OptiPrep™ density gradient centrifugation was 1.18-1.19 g/mL and exosomes 1.10-1.11 g/mL. Comparative protein profiling of SCUF-Exos/-sMVs revealed 354 and 606 unambiguous protein identifications, respectively, with 256 proteins in common. A salient finding was the first report of 350 proteins uniquely identified in sMVs may of which have the potential to enable discrimination of this EV subtype from exosomes (notably, members of the septin family, kinesin-like protein (KIF23), exportin-2/chromosome segregation like-1 protein (CSE1L), and Rac GTPase-activating protein 1 (RACGAP1)). We report for the first time that both SCUF-Exos and SCUF-sMVs isolated from LIM1863 colon cancer cells induce invasion of recipient NIH3T3 cells. Interestingly, the SCUF-sMVs promote invasion to a significantly greater extent (3-fold) than SCUF-Exos. This analytical SCUF method for fractionating EVs is potentially scalable using tangential flow filtration, thereby providing a solid foundation for future in-depth functional studies of EV subtypes using diverse cell types and functional assays.

Extracellular vesicles in the biology of brain tumour stem cells--Implications for inter-cellular communication, therapy and biomarker development

Extracellular vesicles (EVs) act as carriers of molecular and oncogenic signatures present in subsets of tumour cells and tumour-associated stroma, and as mediators of intercellular communication. These processes likely involve cancer stem cells (CSCs). EVs represent a unique pathway of cellular export and cell-to-cell transfer of insoluble molecular regulators such as membrane receptors, signalling proteins and metabolites, thereby influencing the functional integration of cancer cell populations. While mechanisms that control biogenesis, cargo and uptake of different classes of EVs (exosomes, microvesicles, ectosomes, large oncosomes) are poorly understood, they likely remain under the influence of stress-responses, microenvironment and oncogenic processes that define the biology and heterogeneity of human cancers. In glioblastoma (GBM), recent molecular profiling approaches distinguished several disease subtypes driven by distinct molecular, epigenetic and mutational mechanisms, leading to formation of proneural, neural, classical and mesenchymal tumours. Moreover, molecularly distinct clonal cellular lineages co-exist within individual GBM lesions, where they differentiate according to distinct stem cell hierarchies resulting in several facets of tumour heterogeneity and the related potential for intercellular interactions. Glioma stem cells (GSCs) may carry signatures of either proneural or mesenchymal GBM subtypes and differ in several biological characteristics that are, at least in part, represented by the output and repertoire of EV production (vesiculome). We report that vesiculomes differ between known GBM subtypes. EVs may also reflect and influence the equilibrium of the stem cell hierarchy, contain oncogenic drivers and modulate the microenvironment (vascular niche). The GBM/GSC subtype-specific differentials in EV cargo of proteins, transcripts, microRNA and DNA may enable detection of the dynamics of the stem cell compartment and result in biological effects that remain to be fully characterized.

Gliomas and the vascular fragility of the blood brain barrier

Astrocytes, members of the glial family, interact through the exchange of soluble factors or by directly contacting neurons and other brain cells, such as microglia and endothelial cells. Astrocytic projections interact with vessels and act as additional elements of the Blood Brain Barrier (BBB). By mechanisms not fully understood, astrocytes can undergo oncogenic transformation and give rise to gliomas. The tumors take advantage of the BBB to ensure survival and continuous growth. A glioma can develop into a very aggressive tumor, the glioblastoma (GBM), characterized by a highly heterogeneous cell population (including tumor stem cells), extensive proliferation and migration. Nevertheless, gliomas can also give rise to slow growing tumors and in both cases, the afflux of blood, via BBB is crucial. Glioma cells migrate to different regions of the brain guided by the extension of blood vessels, colonizing the healthy adjacent tissue. In the clinical context, GBM can lead to tumor-derived seizures, which represent a challenge to patients and clinicians, since drugs used for its treatment must be able to cross the BBB. Uncontrolled and fast growth also leads to the disruption of the chimeric and fragile vessels in the tumor mass resulting in peritumoral edema. Although hormonal therapy is currently used to control the edema, it is not always efficient. In this review we comment the points cited above, considering the importance of the BBB and the concerns that arise when this barrier is affected.

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

The complexity of glioblastoma multiforme (GBM) and its distinct pathophysiology belong to a unique brain microenvironment and its cellular interactions. Despite extensive evidence of a role for microRNAs in GBM cells, little is known about microRNA-dependent communication between different cellular compartments of the microenvironment that may contribute to the tumor phenotype. While the majority of microRNAs are found intracellularly, a significant number of microRNAs have been observed outside of cells, often encapsulated in secreted extracellular vesicles (EVs). The function of these circulating/secreted microRNAs has not been explored in the context of the brain tumor microenvironment. Establishing how microRNAs are involved in the regulation of oncogenic signaling networks between tumor cells and stroma is likely to add a needed additional layer of complexity to the tumor network, consisting of intercellular communication. More importantly, microRNA/EV signaling may provide an additional therapeutic target for this deadly disease.