Extracellular Vesicle-Mediated Communication between the Glioblastoma and Its Microenvironment

Research progress on astrocyte-derived extracellular vesicles in the pathogenesis and treatment of neurodegenerative diseases

Neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD), pose significant global health risks and represent a substantial public health concern in the contemporary era. A primary factor in the pathophysiology of these disorders is aberrant accumulation and aggregation of pathogenic proteins within the brain and spinal cord. Recent investigations have identified extracellular vesicles (EVs) in the central nervous system (CNS) as potential carriers for intercellular transport of misfolded proteins associated with neurodegenerative diseases. EVs are involved in pathological processes that contribute to various brain disorders including neurodegenerative disorders. Proteins linked to neurodegenerative disorders are secreted and distributed from cell to cell via EVs, serving as a mechanism for direct intercellular communication through the transfer of biomolecules. Astrocytes, as active participants in CNS intercellular communication, release astrocyte-derived extracellular vesicles (ADEVs) that are capable of interacting with diverse target cells. This review primarily focuses on the involvement of ADEVs in the development of neurological disorders and explores their potential dual roles - both advantageous and disadvantageous in the context of neurological disorders. Furthermore, this review examines the current studies investigating ADEVs as potential biomarkers for the diagnosis and treatment of neurodegenerative diseases. The prospects and challenges associated with the application of ADEVs in clinical settings were also comprehensively reviewed.

Extracellular vesicles in glioblastoma: Biomarkers and therapeutic tools

Glioblastoma (GBM) is the most aggressive tumor among the gliomas and intracranial tumors and to date prognosis for GBM patients remains poor, with a median survival typically measured in months to a few years depending on various factors. Although standardized therapies are routinely employed, it is clear that these strategies are unable to cope with heterogeneity and invasiveness of GBM. Furthermore, diagnosis and monitoring of responses to therapies are directly dependent on tissue biopsies or magnetic resonance imaging (MRI) techniques. From this point of view, liquid biopsies are arising as key sources of a variety of biomarkers with the advantage of being easily accessible and monitorable. In this context, extracellular vesicles (EVs), physiologically shed into body fluids by virtually all cells, are gaining increasing interest both as natural carriers of biomarkers and as specific signatures even for GBM. What makes these vesicles particularly attractive is they are also emerging as therapeutical vehicles to treat GBM given their native ability to cross the blood-brain barrier (BBB). Here, we reviewed recent advances on the use of EVs as biomarker for liquid biopsy and nanocarriers for targeted delivery of anticancer drugs in glioblastoma.

Expression of brain-derived neurotrophic factor and formation of migrasome increases in the glioma cells induced by the adipokinetic hormone

OBJECTIVE

It has been previously shown that brain-derived neurotrophic factor is linked with various types of cancer. Brain-derived neurotrophic factor is found to be highly expressed in multiple human cancers and associated with tumor growth, invasion, and metastasis. Adipokinetic hormones are functionally related to the vertebrate glucagon, as they have similar functionalities that manage the nutrient-dependent secretion of these two hormones. Migrasomes are new organelles that contain numerous small vesicles, which aid in transmitting signals between the migrating cells. Therefore, the aim of this study was to investigate the effects of Anax imperator adipokinetic hormone on brain-derived neurotrophic factor expression and ultrastructure of cells in the C6 glioma cell line.

METHODS

The rat C6 glioma cells were treated with concentrations of 5 and 10 Anax imperator adipokinetic hormone for 24 h. The effects of the Anax imperator adipokinetic hormone on the migrasome formation and brain-derived neurotrophic factor expression were analyzed using immunocytochemistry and transmission electron microscope.

RESULTS

The rat C6 glioma cells of the 5 and 10 μM Anax imperator adipokinetic hormone groups showed significantly high expressions of brain-derived neurotrophic factor and migrasomes numbers, compared with the control group.

CONCLUSION

A positive correlation was found between the brain-derived neurotrophic factor expression level and the formation of migrasome, which indicates that the increased expression of brain-derived neurotrophic factor and the number of migrasomes may be involved to metastasis of the rat C6 glioma cell line induced by the Anax imperator adipokinetic hormone. Therefore, the expression of brain-derived neurotrophic factor and migrasome formation may be promising targets for preventing tumor proliferation, invasion, and metastasis in glioma.

A tale of two tumors: differential, but detrimental, effects of glioblastoma extracellular vesicles (EVs) on normal human brain cells

Glioblastomas (GBMs) are dreadful brain tumors with abysmal survival outcomes. GBM EVs dramatically affect normal brain cells (largely astrocytes) constituting the tumor microenvironment (TME). EVs from different patient-derived GBM spheroids induced differential transcriptomic, secretomic, and proteomic effects on cultured astrocytes/brain tissue slices as GBM EV recipients. The net outcome of brain cell differential changes nonetheless converges on increased tumorigenicity. GBM spheroids and brain slices were derived from neurosurgical patient tissues following informed consent. Astrocytes were commercially obtained. EVs were isolated from conditioned culture media by ultrafiltration, ultraconcentration, and ultracentrifugation. EVs were characterized by nanoparticle tracking analysis, electron microscopy, biochemical markers, and proteomics. Astrocytes/brain tissues were treated with GBM EVs before downstream analyses. EVs from different GBMs induced brain cells to alter secretomes with pro-inflammatory or TME-modifying (proteolytic) effects. Astrocyte responses ranged from anti-viral gene/protein expression and cytokine release to altered extracellular signal-regulated protein kinase (ERK1/2) signaling pathways, and conditioned media from EV-treated cells increased GBM cell proliferation. Thus, astrocytes/brain slices treated with different GBM EVs underwent non-identical changes in various 'omics readouts and other assays, indicating "personalized" tumor-specific GBM EV effects on the TME. This raises concern regarding reliance on "model" systems as a sole basis for translational direction. Nonetheless, net downstream impacts from differential cellular and TME effects still led to increased tumorigenic capacities for the different GBMs.

Extracellular vesicles as modulators of glioblastoma progression and tumor microenvironment

Glioblastoma is the most aggressive brain tumor with extremely poor prognosis in adults. Routine treatments include surgery, chemotherapy, and radiotherapy; however, these may lead to rapid relapse and development of therapy-resistant tumor. Glioblastoma cells are known to communicate with macrophages, microglia, endothelial cells, astrocytes, and immune cells in the tumor microenvironment (TME) to promote tumor preservation. It was recently demonstrated that Glioblastoma-derived extracellular vesicles (EVs) participate in bidirectional intercellular communication in the TME. Apart from promoting glioblastoma cell proliferation, migration, and angiogenesis, EVs and their cargos (primarily proteins and miRNAs) can act as biomarkers for tumor diagnosis and prognosis. Furthermore, they can be used as therapeutic tools. In this review, the mechanisms of Glioblastoma-EVs biogenesis and intercellular communication with TME have been summarized. Moreover, there is discussion surrounding EVs as novel diagnostic structures and therapeutic tools for glioblastoma. Finally, unclear questions that require future investigation have been reviewed.

Revealing protein trafficking by proximity labeling-based proteomics

Protein trafficking is a fundamental process with profound implications for both intracellular and intercellular functions. Proximity labeling (PL) technology has emerged as a powerful tool for capturing precise snapshots of subcellular proteomes by directing promiscuous enzymes to specific cellular locations. These enzymes generate reactive species that tag endogenous proteins, enabling their identification through mass spectrometry-based proteomics. In this comprehensive review, we delve into recent advancements in PL-based methodologies, placing particular emphasis on the label-and-fractionation approach and TransitID, for mapping proteome trafficking. These methodologies not only facilitate the exploration of dynamic intracellular protein trafficking between organelles but also illuminate the intricate web of intercellular and inter-organ protein communications.

Detection and characterization of circulating microvesicles containing Shiga toxin type 2 in a rat model of Hemolytic Uremic Syndrome

Shiga toxin producing Escherichia coli (STEC) are foodborne pathogens that release Shiga toxin (Stx), virulence factor responsible for the development of Hemolytic Uremic Syndrome (HUS). Stx causes endothelial cell damage, which leads to platelets deposition and thrombi formation within the microvasculature. It has been described that Stx activates blood cells and induces the shedding of proinflammatory and prothrombotic microvesicles (MVs) containing the toxin. In this sense, it has been postulated that MVs containing Stx2 (MVs-Stx2+) can contribute to the physiopathology of HUS, allowing Stx2 to reach the target organs while evading the immune system. In this work, we propose that circulating MVs-Stx2+ can be a potential biomarker for the diagnosis and prognosis of STEC infections and HUS progression. We developed a rat HUS model by the intraperitoneal injection of a sublethal dose of Stx2 and observed: decrease in body weight, increase of creatinine and urea levels, decrease of creatinine clearance and histological renal damages. After characterization of renal damages, we investigated circulating total MVs and MVs-Stx2+ by flow cytometry at different times after Stx2 injection. Additionally, we evaluated the correlation of biochemical parameters such as creatinine and urea in plasma with MVs-Stx2+. As a result, we found a significant circulation of MVs-Stx2+ at 72 and 96 h after Stx2 injection, nevertheless no correlation with creatinine and urea plasma levels were detected. Our results suggest that MVs-Stx2+ may be an additional biomarker for the characterization and diagnosis of HUS progression. A further analysis is required in order to validate MVs-Stx2+ as biomarker of the disease.

Roles of extracellular vesicles in glioblastoma: foes, friends and informers

Glioblastoma (GB) tumors are one of the most insidious cancers which take over the brain and defy therapy. Over time and in response to treatment the tumor and the brain cells in the tumor microenvironment (TME) undergo many genetic/epigenetic driven changes in their phenotypes and this is reflected in the cellular contents within the extracellular vesicles (EVs) they produce. With the result that some EVs try to subdue the tumor (friends of the brain), while others participate in the glioblastoma takeover (foes of the brain) in a dynamic and ever changing process. Monitoring the contents of these EVs in biofluids can inform decisions based on GB status to guide therapeutic intervention. This review covers primarily recent research describing the different cell types in the brain, as well as the tumor cells, which participate in this EV deluge. This includes EVs produced by the tumor which manipulate the transcriptome of normal cells in their environment in support of tumor growth (foes), as well as responses of normal cells which try to restrict tumor growth and invasion, including traveling to cervical lymph nodes to present tumor neo-antigens to dendritic cells (DCs). In addition EVs released by tumors into biofluids can report on the status of living tumor cells via their cargo and thus serving as biomarkers. However, EVs released by tumor cells and their influence on normal cells in the tumor microenvironment is a major factor in immune suppression and coercion of normal brain cells to join the GB "band wagon". Efforts are being made to deploy EVs as therapeutic vehicles for drugs and small inhibitory RNAs. Increasing knowledge about EVs in the TME is being utilized to track tumor progression and response to therapy and even to weaponize EVs to fight the tumor.

Clinical Theranostics Trademark of Exosome in Glioblastoma Metastasis

Glioblastoma (GBM) is an aggressive type of cancer that has led to the death of a large population. The traditional approach fails to develop a solution for GBM's suffering life. Extensive research into tumor microenvironments (TME) indicates that TME extracellular vesicles (EVs) play a vital role in cancer development and progression. EVs are classified into microvacuoles, apoptotic bodies, and exosomes. Exosomes are the most highlighted domains in cancer research. GBM cell-derived exosomes participate in multiple cancer progression events such as immune suppression, angiogenesis, premetastatic niche formation (PMN), ECM (extracellular matrix), EMT (epithelial-to-mesenchymal transition), metastasis, cancer stem cell development and therapeutic and drug resistance. GBM exosomes also carry the signature of a glioblastoma-related status. The exosome-based GBM examination is part of the new generation of liquid biopsy. It also solved early diagnostic limitations in GBM. Traditional therapeutic approaches do not cross the blood-brain barrier (BBB). Exosomes are a game changer in GBM treatment and it is emerging as a potential platform for effective, efficient, and specific therapeutic development. In this review, we have explored the exosome-GBM interlink, the clinical impact of exosomes on GBM biomarkers, the therapeutics signature of exosomes in GBM, exosome-based research challenges, and future directions in GBM. Therefore, the GBM-derived exosomes offer unique therapeutic opportunities, which are currently under preclinical and clinical testing.

Looking to the Future of the Role of Macrophages and Extracellular Vesicles in Neuroinflammation in ALS

Neuroinflammation is a common pathological feature of amyotrophic lateral sclerosis (ALS). Although scientific evidence to date does not allow defining neuroinflammation as an ALS trigger, its role in exacerbating motor neuron (MNs) degeneration and disease progression is attracting research interest. Activated CNS (Central Nervous System) glial cells, proinflammatory peripheral and infiltrated T lymphocytes and monocytes/macrophages, as well as the immunoreactive molecules they release, represent the active players for the role of immune dysregulation enhancing neuroinflammation. The crosstalk between the peripheral and CNS immune cells significantly correlates with the survival of ALS patients since the modification of peripheral macrophages can downregulate inflammation at the periphery along the nerves and in the CNS. As putative vehicles for misfolded protein and inflammatory mediators between cells, extracellular vesicles (EVs) have also drawn particular attention in the field of ALS. Both CNS and peripheral immune cells release EVs, which are able to modulate the behavior of neighboring recipient cells; unfortunately, the mechanisms involved in EVs-mediated communication in neuroinflammation remain unclear. This review aims to synthesize the current literature regarding EV-mediated cell-to-cell communication in the brain under ALS, with a particular point of view on the role of peripheral macrophages in responding to inflammation to understand the biological process and exploit it for ALS management.

Exosomes as Novel Diagnostic Biomarkers and Therapeutic Tools in Gliomas

Exosomes constitute small extracellular vesicles that contain lipids, proteins, nucleic acids, and glycoconjugates from the secreted cells and are capable of transmitting signals between cells and coordinating cellular communication. By this means, they are ultimately involved in physiology and disease, including development, homeostasis, and immune system regulation, as well as contributing to tumor progression and neurodegenerative diseases pathology. Recent studies have shown that gliomas secrete a panel of exosomes which have been associated with cell invasion and migration, tumor immune tolerance, potential for malignant transformation, neovascularization, and resistance to treatment. Exosomes have therefore emerged as intercellular communicators, which mediate the tumor-microenvironment interactions and exosome-regulated glioma cell stemness and angiogenesis. They may induce tumor proliferation and malignancy in normal cells by carrying pro-migratory modulators from cancer cells as well as many different molecular cancer modifiers, such as oncogenic transcripts, miRNAs, mutant oncoproteins, etc., which promote the communication of cancer cells with the surrounding stromal cells and provide valuable information on the molecular profile of the existing tumor. Moreover, engineered exosomes can provide an alternative system for drug delivery and enable efficient treatment. In the present review, we discuss the latest findings regarding the role of exosomes in glioma pathogenesis, their utility in non-invasive diagnosis, and potential applications to treatment.

Extracellular vesicles in the glioblastoma microenvironment: A diagnostic and therapeutic perspective

Glioblastoma (GBM), is the most malignant form of gliomas and the most common and lethal primary brain tumor in adults. Conventional cancer treatments have limited to no efficacy on GBM. GBM cells respond and adapt to the surrounding brain parenchyma known as tumor microenvironment (TME) to promote tumor preservation. Among specific TME, there are 3 of particular interest for GBM biology: the perivascular niche, the subventricular zone neurogenic niche, and the immune microenvironment. GBM cells and TME cells present a reciprocal feedback which results in tumor maintenance. One way that these cells can communicate is through extracellular vesicles. These vesicles include exosomes and microvesicles that have the ability to carry both cancerous and non-cancerous cargo, such as miRNA, RNA, proteins, lipids, and DNA. In this review we will discuss the booming topic that is extracellular vesicles, and how they have the novelty to be a diagnostic and targetable vehicle for GBM.

Cellular Conversations in Glioblastoma Progression, Diagnosis and Treatment

Glioblastoma (GBM) is the most frequent malignancy among primary brain tumors in adults and one of the worst 5-year survival rates (< 7%) among all human cancers. Till now, treatments that target particular cell or intracellular metabolism have not improved patients' survival. GBM recruits healthy brain cells and subverts their processes to create a microenvironment that contributes to supporting tumor progression. This microenvironment encompasses a complex network in which malignant cells interact with each other and with normal and immune cells to promote tumor proliferation, angiogenesis, metastasis, immune suppression, and treatment resistance. Communication can be direct via cell-to-cell contact, mainly through adhesion molecules, tunneling nanotubes, gap junctions, or indirect by conventional paracrine signaling by cytokine, neurotransmitter, and extracellular vesicles. Understanding these communication routes could open up new avenues for the treatment of this lethal tumor. Hence, therapeutic approaches based on glioma cells` communication have recently drawn attention. This review summarizes recent findings on the crosstalk between glioblastoma cells and their tumor microenvironment, and the impact of this conversation on glioblastoma progression. We also discuss the mechanism of communication of glioma cells and their importance as therapeutic targets and diagnostic and prognostic biomarkers. Overall, understanding the biological mechanism of specific interactions in the tumor microenvironment may help in predicting patient prognosis and developing novel therapeutic strategies to target GBM.

Coculture with Neural Stem Cells May Shift the Transcription Profile of Glioblastoma Multiforme towards Cancer-Specific Stemness

Glioblastoma multiforme (GBM) possesses a small but significant population of cancer stem cells (CSCs) thought to play a role in its invasiveness, recurrence, and metastasis. The CSCs display transcriptional profiles for multipotency, self-renewal, tumorigenesis, and therapy resistance. There are two possible theories regarding the origin of CSCs in the context of neural stem cells (NSCs); i.e., NSCs modify cancer cells by conferring them with cancer-specific stemness, or NSCs themselves are transformed into CSCs due to the tumor environment created by cancer cells. To test the theories and to investigate the transcriptional regulation of the genes involved in CSC formation, we cocultured NSC and GBM cell lines together. Where genes related to cancer stemness, drug efflux, and DNA modification were upregulated in GBM, they were downregulated in NSCs upon coculture. These results indicate that cancer cells shift the transcriptional profile towards stemness and drug resistance in the presence of NSCs. Concurrently, GBM triggers NSCs differentiation. Because the cell lines were separated by a membrane (0.4 µm pore size) to prevent direct contact between GBM and NSCs, cell-secreted signaling molecules and extracellular vesicles (EVs) are likely involved in reciprocal communication between NSCs and GBM, causing transcription modification. Understanding the mechanism of CSC creation will aid in the identification of precise molecular targets within the CSCs to exterminate them, which, in turn, will increase the efficacy of chemo-radiation treatment.

Antibody Profiling and In Silico Functional Analysis of Differentially Reactive Antibody Signatures of Glioblastomas and Meningiomas

Studies on tumor-associated antigens in brain tumors are sparse. There is scope for enhancing our understanding of molecular pathology, in order to improve on existing forms, and discover new forms, of treatment, which could be particularly relevant to immuno-oncological strategies. To elucidate immunological differences, and to provide another level of biological information, we performed antibody profiling, based on a high-density protein array (containing 8173 human transcripts), using IgG isolated from the sera of n = 12 preoperative and n = 16 postoperative glioblastomas, n = 26 preoperative and n = 29 postoperative meningiomas, and n = 27 healthy, cancer-free controls. Differentially reactive antigens were compared to gene expression data from an alternate public GBM data set from OncoDB, and were analyzed using the Reactome pathway browser. Protein array analysis identified approximately 350-800 differentially reactive antigens, and revealed different antigen profiles in the glioblastomas and meningiomas, with approximately 20-30%-similar and 10-15%-similar antigens in preoperative and postoperative sera, respectively. Seroreactivity did not correlate with OncoDB-derived gene expression. Antigens in the preoperative glioblastoma sera were enriched for signaling pathways, such as signaling by Rho-GTPases, COPI-mediated anterograde transport and vesicle-mediated transport, while the infectious disease, SRP-dependent membrane targeting cotranslational proteins were enriched in the meningiomas. The pre-vs. postoperative seroreactivity in the glioblastomas was enriched for antigens, e.g., platelet degranulation and metabolism of lipid pathways; in the meningiomas, the antigens were enriched in infectious diseases, metabolism of amino acids and derivatives, and cell cycle. Antibody profiling in both tumor entities elucidated several hundred antigens and characteristic signaling pathways that may provide new insights into molecular pathology and may be of interest for the development of new treatment strategies.

Mesenchymal stem cell-derived exosomes as a new therapeutic strategy in the brain tumors

Brain tumors are one of the most mortal cancers, leading to many deaths among kids and adults. Surgery, chemotherapy, and radiotherapy are available options for brain tumor treatment. However, these methods are not able to eradicate cancer cells. The blood-brain barrier (BBB) is one of the most important barriers to treat brain tumors that prevents adequate drug delivery to brain tissue. The connection between different brain parts is heterogeneous and causes many challenges in treatment. Mesenchymal stem cells (MSCs) migrate to brain tumor cells and have anti-tumor effects by delivering cytotoxic compounds. They contain very high regenerative properties, as well as support the immune system. MSCs-based therapy involves cell replacement and releases various vesicles, including exosomes. Exosomes receive more attention due to their excellent stability, less immunogenicity and toxicity compare to cells. Exosomes derived from MSCs can develop a powerful therapeutic strategy for different diseases and be a hopeful candidate for cell-based and cell-free regenerative medicine. These nanoparticles contain nucleic acid, proteins, lipids, microRNAs, and other biologically active substances. Many studies show that each microRNA can prevent angiogenesis, migration, and metastasis in glioblastoma. These exosomes can-act as a suitable nanoparticle carrier for therapeutic applications of brain tumors by passing through the BBB. In this review, we discuss potential applications of MSC and their produced exosomes in the treatment of brain tumors.

Extracellular vesicles, from the pathogenesis to the therapy of neurodegenerative diseases

Extracellular vesicles (EVs) are small bilipid layer-enclosed vesicles that can be secreted by all tested types of brain cells. Being a key intercellular communicator, EVs have emerged as a key contributor to the pathogenesis of various neurodegenerative diseases (NDs) including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease through delivery of bioactive cargos within the central nervous system (CNS). Importantly, CNS cell-derived EVs can be purified via immunoprecipitation, and EV cargos with altered levels have been identified as potential biomarkers for the diagnosis and prognosis of NDs. Given the essential impact of EVs on the pathogenesis of NDs, pathological EVs have been considered as therapeutic targets and EVs with therapeutic effects have been utilized as potential therapeutic agents or drug delivery platforms for the treatment of NDs. In this review, we focus on recent research progress on the pathological roles of EVs released from CNS cells in the pathogenesis of NDs, summarize findings that identify CNS-derived EV cargos as potential biomarkers to diagnose NDs, and comprehensively discuss promising potential of EVs as therapeutic targets, agents, and drug delivery systems in treating NDs, together with current concerns and challenges for basic research and clinical applications of EVs regarding NDs.

Biological implications and clinical potential of invasion and migration related miRNAs in glioma

Gliomas are the most common primary malignant brain tumors and are highly aggressive. Invasion and migration are the main causes of poor prognosis and treatment resistance in gliomas. As migration and invasion occur, patient survival and prognosis decline dramatically. MicroRNAs (miRNAs) are small, non-coding 21–23 nucleotides involved in regulating the malignant phenotype of gliomas, including migration and invasion. Numerous studies have demonstrated the mechanism and function of some miRNAs in glioma migration and invasion. However, the biological and clinical significance (including diagnosis, prognosis, and targeted therapy) of glioma migration and invasion-related miRNAs have not been systematically discussed. This paper reviews the progress of miRNAs-mediated migration and invasion studies in glioma and discusses the clinical value of migration and invasion-related miRNAs as potential biomarkers or targeted therapies for glioma. In addition, these findings are expected to translate into future directions and challenges for clinical applications. Although many biomarkers and their biological roles in glioma invasion and migration have been identified, none have been specific so far, and further exploration of clinical treatment is still in progress; therefore, we aimed to further identify specific markers that may guide clinical treatment and improve the quality of patient survival.

Exosomes to control glioblastoma multiforme: Investigating the effects of mesenchymal stem cell-derived exosomes on C6 cells in vitro

Glioblastoma multiforme (GBM) is a common, aggressive, fast-growing tumor of the central nervous system that currently has no effective treatment. Although stem cell therapy has shown promising in vitro achievements, the blood-brain barrier (BBB) has always been a major hurdle to clinical success. To overcome this challenge, exosomes have been targeted as attractive drug delivery agents in numerous studies since they are small enough to enter the BBB. Furthermore, exosomes' characteristics and compositions are directly determined by the parent cell and these heritable traits affect their cell interactions. This article focuses on exosomes as an alternative to stem cell therapy to regulate glioma cell activity. Exosomes were isolated from rat bone marrow mesenchymal stem cells (rBMMSCs) by ultracentrifugation method and then characterized via western blot, dynamic light scattering, scanning, and transmission electron microscopy. Next, various concentrations of the exosomes were incubated with C6 cells and their effects at different time points were evaluated in vitro. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Annexin/Pi assay results confirmed that the isolated exosomes cause cell death mostly through apoptosis, and a linear correlation was observed between exosomes' concentration and their cytotoxicity. Following that, the scratch test, colony formation test, and Transwell assay confirmed exosomes' significant impact on the migration and invasion behavior of C6 cells. For the first time, rBMMSC-derived exosomes have been used as a single treatment for GBM rather than in combination with other treatments or as a pharmaceutical carrier.

AQP4-dependent glioma cell features affect the phenotype of surrounding cells via extracellular vesicles

Background

Extracellular vesicles (EVs) are membrane-enclosed particles released systemically by all cells, including tumours. Tumour EVs have been shown to manipulate their local environments as well as distal targets to sustain the tumour in a variety of tumours, including glioblastoma (GBM).

We have previously demonstrated the dual role of the glial water channel aquaporin-4 (AQP4) protein in glioma progression or suppression depending on its aggregation state. However, its possible role in communication mechanisms in the microenvironment of malignant gliomas remains to be unveiled.

Results

Here we show that in GBM cells AQP4 is released via EVs that are able to affect the GBM microenvironment. To explore this role, EVs derived from invasive GBM cells expressing AQP4-tetramers or apoptotic GBM cells expressing orthogonal arrays of particles (AQP4-OAPs) were isolated, using a differential ultracentrifugation method, and were added to pre-seeded GBM cells. Confocal microscopy analysis was used to visualize the interaction and uptake of AQP4-containing EVs by recipient cells. Chemoinvasion and Caspase3/7 activation assay, performed on recipient cells after EVs uptake, revealed that EVs produced by AQP4-tetramers expressing cells were able to drive surrounding tumour cells toward the migratory phenotype, whereas EVs produced by AQP4-OAPs expressing cells drive them toward the apoptosis pathway.

Conclusion

This study demonstrates that the different GBM cell phenotypes can be transferred by AQP4-containing EVs able to influence tumour cell fate toward invasiveness or apoptosis.

This study opens a new perspective on the role of AQP4 in the brain tumour microenvironment associated with the EV-dependent communication mechanism.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00888-2.

Canine B Cell Lymphoma- and Leukemia-Derived Extracellular Vesicles Moderate Differentiation and Cytokine Production of T and B Cells In Vitro

Extracellular vesicles (EVs) are formed in physiological and pathological conditions by almost all mammalian cells. They are known as submicron “molecules” that transport and horizontally transfer their cargo from maternal cells to donor cells. Moreover, cancer cells produce tumor-derived EVs (TEVs), which are present in blood of patients with solid tumors and those with hematological malignancies. Their role in evading immune system surveillance and induction of immunosuppression in hematological cancer is limited. According to the authors’ best knowledge, there is no information about the impact of TEVs from canine lymphoma (CLBL-1) and leukemia (CLB70) on lymphocytes isolated from peripheral blood mononuclear cells (PBMCs). In conclusion, we demonstrate in in vitro experiments that CLBL-1 EVs and CLB70 EVs are effectively taken up by T and B lymphocytes. TEVs decrease the percentage of B lymphocytes and increase that of T lymphocytes, and change T cells’ phenotype into the effector memory (EM) or terminally differentiated effector memory (TEMRA) subtype after in vitro co-culturing. Moreover, CLBL70 EVs have pro-tumorogenic properties by inhibiting the production of CD8+IL-17+ cells.

Alternating exosomes and their mimetics as an emergent strategy for targeted cancer therapy

Exosomes, a subtype of the class of extracellular vesicles and nano-sized particles, have a specific membrane structure that makes them an alternative proposition to combat with cancer through slight modification. As constituents of all most all the primary body fluids, exosomes establish the status of intercellular communication. Exosomes have specific proteins/mRNAs and miRNAs which serve as biomarkers, imparting a prognostic tool in clinical and disease pathologies. They have efficient intrinsic targeting potential and efficacy. Engineered exosomes are employed to deliver therapeutic cargos to the targeted tumor cell or the recipient. Exosomes from cancer cells bring about changes in fibroblast via TGFβ/Smad pathway, augmenting the tumor growth. These extracellular vesicles are multidimensional in terms of the functions that they perform. We herein discuss the uptake and biogenesis of exosomes, their role in various facets of cancer studies, cell-to-cell communication and modification for therapeutic and diagnostic use.

miRNome and Proteome Profiling of Small Extracellular Vesicles Secreted by Human Glioblastoma Cell Lines and Primary Cancer Stem Cells

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. Despite available therapeutic interventions, it is very difficult to treat, and a cure is not yet available. The intra-tumoral GBM heterogeneity is a crucial factor contributing to poor clinical outcomes. GBM derives from a small heterogeneous population of cancer stem cells (CSCs). In cancer tissue, CSCs are concentrated within the so-called niches, where they progress from a slowly proliferating phase. CSCs, as most tumor cells, release extracellular vesicles (EVs) into the surrounding microenvironment. To explore the role of EVs in CSCs and GBM tumor cells, we investigated the miRNA and protein content of the small EVs (sEVs) secreted by two GBM-established cell lines and by GBM primary CSCs using omics analysis. Our data indicate that GBM-sEVs are selectively enriched for miRNAs that are known to display tumor suppressor activity, while their protein cargo is enriched for oncoproteins and tumor-associated proteins. Conversely, among the most up-regulated miRNAs in CSC-sEVs, we also found pro-tumor miRNAs and proteins related to stemness, cell proliferation, and apoptosis. Collectively, our findings support the hypothesis that sEVs selectively incorporate different miRNAs and proteins belonging both to fundamental processes (e.g., cell proliferation, cell death, stemness) as well as to more specialized ones (e.g., EMT, membrane docking, cell junction organization, ncRNA processing).

Ribosomes and Ribosomal Proteins Promote Plasticity and Stemness Induction in Glioma Cells via Reprogramming

Glioblastoma multiforme (GBM) is a lethal tumor that develops in the adult brain. Despite advances in therapeutic strategies related to surgical resection and chemo-radiotherapy, the overall survival of patients with GBM remains unsatisfactory. Genetic research on mutation, amplification, and deletion in GBM cells is important for understanding the biological aggressiveness, diagnosis, and prognosis of GBM. However, the efficacy of drugs targeting the genetic abnormalities in GBM cells is limited. Investigating special microenvironments that induce chemo-radioresistance in GBM cells is critical to improving the survival and quality of life of patients with GBM. GBM cells acquire and maintain stem-cell-like characteristics via their intrinsic potential and extrinsic factors from their special microenvironments. The acquisition of stem-cell-like phenotypes and aggressiveness may be referred to as a reprogramming of GBM cells. In addition to protein synthesis, deregulation of ribosome biogenesis is linked to several diseases including cancer. Ribosomal proteins possess both tumor-promotive and -suppressive functions as extra-ribosomal functions. Incorporation of ribosomes and overexpression of ribosomal protein S6 reprogram and induce stem-cell-like phenotypes in GBM cells. Herein, we review recent literature and our published data on the acquisition of aggressiveness by GBM and discuss therapeutic options through reprogramming.

Potential Neurotoxic Effects of Glioblastoma-Derived Exosomes in Primary Cultures of Cerebellar Neurons via Oxidant Stress and Glutathione Depletion

High-grade gliomas are the most fatal brain tumors. Grade 4 gliomas are called glioblastoma multiforme (GBM), which are associated with the poorest survival and a 5-year survival rate of less than 4%. Many patients with GBM developed concomitant cognitive dysfunctions and epilepsy. Although the cognitive decline is well defined in glioblastomas, the neurotoxic factors underlying this pathology are not well understood in GBM patients. In this study, we aimed to investigate whether GBM-derived exosomes play a role in neuronal toxicity. For this purpose, exosomes obtained from T98G and U373 GBM cells were applied to primary neuron culture at different concentrations. Subsequently, MTT, LDH, GSH, TAS, and TOS tests were performed. Both GBM-derived exosomes induced a dose-dependent and statistically significant increase of LDH release in cerebellar neurons. MTT assay revealed as both T98G and U373 GBM-derived exosomes induced dose-dependent neurotoxic effects in cerebellar neurons. To the best of our knowledge, this study is the first study demonstrating the toxic potential of GBM-derived exosomes to primary neurons, which may explain the peritumoral edema and cognitive decline in GBM patients.

Glioma extracellular vesicles for precision medicine: prognostic and theragnostic application

EV produced by tumour cells carry a diverse population of proteins, lipids, DNA, and RNA molecules throughout the body and appear to play an important role in the overall development of the disease state, according to growing data. Gliomas account for a sizable fraction of all primary brain tumours and the vast majority of brain malignancies. Glioblastoma multiforme (GBM) is a kind of grade IV glioma that has a very dismal prognosis despite advancements in diagnostic methods and therapeutic options. The authors discuss advances in understanding the function of extracellular vesicles (EVs), in overall glioma growth, as well as how recent research is uncovering the utility of EVs in glioma diagnostics, prognostic and therapeutics approaches.

HOTAIRM1 Maintained the Malignant Phenotype of tMSCs Transformed by GSCs via E2F7 by Binding to FUS

Objective. Mesenchymal stromal/stem cells (MSCs) are an important part of the glioma microenvironment and are involved in the malignant progression of glioma. In our previous study, we showed that MSCs can be induced to a malignant phenotype (tMSCs) by glioma stem cells (GSCs) in the microenvironment. However, the potential mechanism by which tMSCs maintain their malignant phenotype after malignant transformation has not been fully clarified. Methods. The expression of HOTAIRM1, FUS, and E2F7 was detected by qRT-PCR. Clone formation, EdU, and Transwell assay were used to explore the role of HOTAIRM1, FUS, and E2F7 on the proliferation, migration, and invasion of tMSCs. Bioinformatics analysis and RNA immunoprecipitation were used to explore the relation among HOTAIRM1, FUS, and E2F7. Results. HOTAIRM1 was upregulated in tMSCs compared with MSCs. Loss- and gain-of-function assays showed that HOTAIRM1 promoted the proliferation, migration, and invasion of tMSCs. qRT-PCR and functional assays revealed that E2F7 might be the downstream target of HOTAIRM1. A further study of the mechanism showed that HOTAIRM1 could bind to FUS, an RNA-binding protein (RBP), and thus regulate E2F7, which could promote the malignant phenotype of tMSCs. Conclusion. Our study revealed that the HOTAIRM1/FUS/E2F7 axis is involved in the malignant progression of tMSCs transformed by GSCs in the glioma microenvironment and may function as a novel target for glioma therapy.

Emerging Concepts on the Role of Extracellular Vesicles and Its Cargo Contents in Glioblastoma-Microglial Crosstalk

Glioblastoma multiforme is the most common, highly aggressive malignant brain tumor which is marked by highest inter- and intra-tumoral heterogeneity. Despite, immunotherapy, and combination therapies developed; the clinical trials often result into large number of failures. Often cancer cells are known to communicate with surrounding cells in tumor microenvironment (TME). Extracellular vesicles (EVs) consisting of diverse cargo mediates this intercellular communication and is believed to modulate the immune function against GBM. Tumor-associated microglia (TAM), though being the resident innate immune cell of CNS, is known to attain pro-tumorigenic M2 phenotype, and this immunomodulation is aided by extracellular vesicle-mediated transfer of oncogenic, immunomodulatory molecules. Besides, oncogenic proteins, long non-coding RNAs (lncRNAs), are believed to carry oncogenic potential, and therefore, understanding the mechanism leading to microglial dysregulation mediated by GBM-derived extracellular vesicle (GDEV) lncRNAs becomes crucial. This review focuses on current understanding of role of GDEV and lncRNA in microglial dysfunction and its potential as a therapeutic target.

Exosomal miR-205-5p enhances angiogenesis and nasopharyngeal carcinoma metastasis by targeting desmocollin-2

The aim of this study was to investigate whether and how exosomal miR-205-5p regulated angiogenesis and nasopharyngeal carcinoma (NPC) metastasis. We found that up-regulated serum exosomal miR-205-5p levels were associated with NPC progression and worse overall survival of NPC patients. miR-205-5p over-expression significantly increased tube formation, wound healing, migration and invasion of NPC cells, and lung metastasis of NPC tumors, whereas miR-205-5p inhibition had opposite effects. Exosomal miR-205-5p from NPC cells promoted the migration, tube formation, and microvessel density (MVD) of HUVECs in vitro and in vivo. Furthermore, bioinformatics-, luciferase reporter-, and biotinylated miR-205-5p-based pull-down assays indicated that miR-205-5p directly bound to the 3′ UTR of desmocollin-2 (DSC2). Exosomal miR-205-5p targeted DSC2 to enhance the EGFR/ERK signaling and MMP2/MMP9 expression, promoting angiogenesis and NPC metastasis, which was abrogated by DSC2 over-expression. Finally, the levels of miR-205-5p transcripts were positively correlated with MVD but negatively with DSC2 expression in NPC tissues, and patients with miR-205^high/DSC2^low NPC had worse overall survival. In conclusion, exosomal miR-205-5p promotes angiogenesis and NPC metastasis by targeting DSC2 to enhance EGFR/ERK signaling and MMP expression. This exosomal/miR-205-5p/EGFR/ERK axis may be a new therapeutic target for intervention of NPC metastasis.

Liquid Biopsy for Monitoring EC Patients: Towards Personalized Treatment

Simple Summary

Although the field of liquid biopsy is clearly having an effect on other tumour types, in endometrial cancer (EC) there is important work to do to implement the analysis of circulating biomarkers into the clinical routine. One of the most evident contexts of application is the disease follow-up in both localized and advanced diseases, which at present is primarily made by imaging techniques. In the present review, we conducted an overview of the circulating biomarkers with the potential to be used as monitoring biomarkers in endometrial tumours and highlighted the key challenges for their translation into the patients’ management in order to help researchers to better focus their work in this field.

Abstract

Endometrial cancer (EC) is the most frequent gynecological cancer in developed countries and its incidence shows an increasing trend. Fortunately, the prognosis of the disease is good when the tumour is diagnosed in an early phase, but some patients recur after surgery and develop distant metastasis. The therapy options for EC for advanced disease are more limited than for other tumours. Therefore, the application of non-invasive strategies to anticipate the recurrence of localized tumours and guide the treatment in advanced stages represents a clear requirement to improve the survival and quality of life of patients with EC. To achieve this desired precision oncology, it is necessary to invest in the identification and validation of circulating markers that allow a more effective stratification and monitoring of patients. We here review the main advances made for the evaluation of circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), circulating extracellular vesicles (cEVs), and other non-invasive biomarkers as a monitoring tool in the context of localized and advanced endometrial tumours, with the aim of providing a global perspective of the achievements and the key areas in which the use of these markers can be developed into a real clinical tool.

Adenosinergic Signaling as a Key Modulator of the Glioma Microenvironment and Reactive Astrocytes

Astrocytes are numerous glial cells of the central nervous system (CNS) and play important roles in brain homeostasis. These cells can directly communicate with neurons by releasing gliotransmitters, such as adenosine triphosphate (ATP) and glutamate, into the multipartite synapse. Moreover, astrocytes respond to tissue injury in the CNS environment. Recently, astrocytic heterogeneity and plasticity have been discussed by several authors, with studies proposing a spectrum of astrocytic activation characterized by A1/neurotoxic and A2/neuroprotective polarization extremes. The fundamental roles of astrocytes in communicating with other cells and sustaining homeostasis are regulated by purinergic signaling. In the CNS environment, the gliotransmitter ATP acts cooperatively with other glial signaling molecules, such as cytokines, which may impact CNS functions by facilitating/inhibiting neurotransmitter release. Adenosine (ADO), the main product of extracellular ATP metabolism, is an important homeostatic modulator and acts as a neuromodulator in synaptic transmission via P1 receptor sensitization. Furthermore, purinergic signaling is a key factor in the tumor microenvironment (TME), as damaged cells release ATP, leading to ADO accumulation in the TME through the ectonucleotidase cascade. Indeed, the enzyme CD73, which converts AMP to ADO, is overexpressed in glioblastoma cells; this upregulation is associated with tumor aggressiveness. Because of the crucial activity of CD73 in these cells, extracellular ADO accumulation in the TME contributes to sustaining glioblastoma immune escape while promoting A2-like activation. The present review describes the importance of ADO in modulating astrocyte polarization and simultaneously promoting tumor growth. We also discuss whether targeting of CD73 to block ADO production can be used as an alternative cancer therapy.

Liquid biopsy in gliomas: A RANO review and proposals for clinical applications

BACKGROUND

There is an extensive literature highlighting the utility of blood-based liquid biopsies in several extracranial tumors for diagnosis and monitoring.

METHODS

The RANO (Response Assessment in Neuro-Oncology) group developed a multidisciplinary international Task Force to review the English literature on liquid biopsy in gliomas focusing on the most frequently used techniques, that is circulating tumor DNA, circulating tumor cells, and extracellular vesicles in blood and CSF.

RESULTS

ctDNA has a higher sensitivity and capacity to represent the spatial and temporal heterogeneity in comparison to circulating tumor cells. Exosomes have the advantages to cross an intact blood-brain barrier and carry also RNA, miRNA, and proteins. Several clinical applications of liquid biopsies are suggested: to establish a diagnosis when tissue is not available, monitor the residual disease after surgery, distinguish progression from pseudoprogression, and predict the outcome.

CONCLUSIONS

There is a need for standardization of biofluid collection, choice of an analyte, and detection strategies along with rigorous testing in future clinical trials to validate findings and enable entry into clinical practice.

Tissue-derived extracellular vesicles in cancers and non-cancer diseases: Present and future

Extracellular vesicles (EVs) are lipid‐bilayer membrane structures secreted by most cell types. EVs act as messengers via the horizontal transfer of lipids, proteins, and nucleic acids, and influence various pathophysiological processes in both parent and recipient cells. Compared to EVs obtained from body fluids or cell culture supernatants, EVs isolated directly from tissues possess a number of advantages, including tissue specificity, accurate reflection of tissue microenvironment, etc., thus, attention should be paid to tissue‐derived EVs (Ti‐EVs). Ti‐EVs are present in the interstitium of tissues and play pivotal roles in intercellular communication. Moreover, Ti‐EVs provide an excellent snapshot of interactions among various cell types with a common histological background. Thus, Ti‐EVs may be used to gain insights into the development and progression of diseases. To date, extensive investigations have focused on the role of body fluid‐derived EVs or cell culture‐derived EVs; however, the number of studies on Ti‐EVs remains insufficient. Herein, we summarize the latest advances in Ti‐EVs for cancers and non‐cancer diseases. We propose the future application of Ti‐EVs in basic research and clinical practice. Workflows for Ti‐EV isolation and characterization between cancers and non‐cancer diseases are reviewed and compared. Moreover, we discuss current issues associated with Ti‐EVs and provide potential directions.

Current landscape of tumor-derived exosomal ncRNAs in glioma progression, detection, and drug resistance

Glioma is the most common and fatal tumor of the central nervous system in humans. Despite advances in surgery, radiotherapy, and chemotherapeutic agents, glioma still has a poor prognosis. The tumor microenvironment (TME) of glioma is of highly complex heterogeneity, which relies on a network-based communication between glioma cells and other stromal cell types. Exosomes are the most common type of naturally occurring extracellular vesicles, ranging in size from 40 to 160 nm, and can serve as carriers for proteins, RNAs, and other biologically active molecules. Recent evidence has shown that glioma-derived exosomes (GDEs) can be integrally detected in the local tissue and circulatory blood samples, and also can be transferred to recipient cells to mediate transmission of genetic information. Non-coding RNAs (ncRNAs) mainly including microRNA, long non-coding RNA, and circular RNA, account for a large portion of the human transcriptome. A broad range of ncRNAs encapsulated in GDEs is reported to exert regulatory functions in various pathophysiological processes of glioma. Herein, this review summarizes the latest findings on the fundamental roles of GDE ncRNAs that have been implicated in glioma behaviors, immunological regulation, diagnosis potential, and treatment resistance, as well as the current limitations and perspectives. Undoubtedly, a thorough understanding of this area will provide comprehensive insights into GDE-based clinical applications for combating gliomas.

Roles of Microvesicles in Tumor Progression and Clinical Applications

Microvesicles are extracellular vesicles with diameter ranging from 100 to 1000 nm that are secreted by tumor cells or other cells in the tumor microenvironment. A growing number of studies demonstrate that tumor-derived microvesicles are involved in tumor initiation and progression, as well as drug resistance. In addition, tumor-derived microvesicles carry a variety of immunogenic molecules and inhibit tumor response to immunotherapy; therefore, they can be exploited for use in tumor vaccines. Moreover, because of their high stability, tumor-derived microvesicles extracted from body fluids can be used as biomarkers for cancer diagnosis or assessment of prognosis. Tumor-derived microvesicles can also be deployed to reverse drug resistance of tumor regenerative cells, or to deliver chemotherapeutic drugs and oncolytic adenovirus for the treatment of cancer patients. This review summarizes the general characteristics of tumor-derived microvesicles, focusing on their biological characteristics, their involvement in tumor progression, and their clinical applications.

BSA-MnO2-SAL multifunctional nanoparticle-mediated M1 macrophages polarization for glioblastoma therapy

Glioblastoma (GBM) is a type of brain tumour with a very high fatality rate. Owing to the presence of the blood-brain barrier (BBB), it is difficult for drugs to reach the tumour site; thus, there has been little progress in GBM chemotherapeutics. Furthermore, the malignant growth of tumours largely depends on the tumour microenvironment. GBM is especially prevalent in slightly acidic, hydrogen peroxide (H₂O₂)-rich, hypoxic, and immunosuppressive microenvironments. Tumour-supporting macrophages (M₂ macrophages) are a type of immune cell that promote tumour growth. Therefore, targeting M₂ macrophages and repolarizing them into tumour-suppressor macrophages (M₁ macrophages) are important strategies for GBM treatment. Salinomycin (SAL) is an anti-tumour drug that can improve the tumour immune microenvironment. Interestingly, we found that SAL promoted the expression of M₁ macrophages in vitro, but its ability was limited in vivo because of the presence of the BBB. In this study, we combined SAL and MnO₂ to design bovine serum albumin-MnO₂-SAL (BMS), a nanoparticle that responds to acidic and H₂O₂-rich microenvironments. Our experimental results showed that BMS reduced GBM growth efficiency and had the ability to penetrate the BBB. It also enhanced the repolarization ability of SAL owing to the production of Mn²⁺ after decomposition, which could be applied in Magnetic Resonance Imaging (MRI). This study demonstrated that the multifunctional nanoparticle BMS is of great significance in inhibiting orthotopic GBM growth and improving immunosuppressive microenvironments.

SOX transcription factors and glioma stem cells: Choosing between stemness and differentiation

Glioblastoma (GBM) is the most common, most aggressive and deadliest brain tumor. Recently, remarkable progress has been made towards understanding the cellular and molecular biology of gliomas. GBM tumor initiation, progression and relapse as well as resistance to treatments are associated with glioma stem cells (GSCs). GSCs exhibit a high proliferation rate and self-renewal capacity and the ability to differentiate into diverse cell types, generating a range of distinct cell types within the tumor, leading to cellular heterogeneity. GBM tumors may contain different subsets of GSCs, and some of them may adopt a quiescent state that protects them against chemotherapy and radiotherapy. GSCs enriched in recurrent gliomas acquire more aggressive and therapy-resistant properties, making them more malignant, able to rapidly spread. The impact of SOX transcription factors (TFs) on brain tumors has been extensively studied in the last decade. Almost all SOX genes are expressed in GBM, and their expression levels are associated with patient prognosis and survival. Numerous SOX TFs are involved in the maintenance of the stemness of GSCs or play a role in the initiation of GSC differentiation. The fine-tuning of SOX gene expression levels controls the balance between cell stemness and differentiation. Therefore, innovative therapies targeting SOX TFs are emerging as promising tools for combatting GBM. Combatting GBM has been a demanding and challenging goal for decades. The current therapeutic strategies have not yet provided a cure for GBM and have only resulted in a slight improvement in patient survival. Novel approaches will require the fine adjustment of multimodal therapeutic strategies that simultaneously target numerous hallmarks of cancer cells to win the battle against GBM.

Old Stars and New Players in the Brain Tumor Microenvironment

In recent years, the direct interaction between cancer cells and tumor microenvironment (TME) has emerged as a crucial regulator of tumor growth and a promising therapeutic target. The TME, including the surrounding peritumoral regions, is dynamically modified during tumor progression and in response to therapies. However, the mechanisms regulating the crosstalk between malignant and non-malignant cells are still poorly understood, especially in the case of glioma, an aggressive form of brain tumor. The presence of unique brain-resident cell types, namely neurons and glial cells, and an exceptionally immunosuppressive microenvironment pose additional important challenges to the development of effective treatments targeting the TME. In this review, we provide an overview on the direct and indirect interplay between glioma and neuronal and glial cells, introducing new players and mechanisms that still deserve further investigation. We will focus on the effects of neural activity and glial response in controlling glioma cell behavior and discuss the potential of exploiting these cellular interactions to develop new therapeutic approaches with the aim to preserve proper brain functionality.

Extracellular vesicles: the key for precision medicine in glioblastoma

Glioblastoma (GBM) represents the most aggressive and lethal disease of the central nervous system. Diagnosis is delayed following the occurrence of symptoms, and treatment is based on standardized approaches that are unable to cope with its heterogeneity, mutability, and invasiveness. The follow-up of patients relies on burdensome schedules for magnetic resonance imaging (MRI). However, to personalize treatment, biomarkers and liquid biopsy still represent unmet clinical needs. Extracellular vesicles (EVs) may be the key to revolutionize the entire process of care for patients with GBM. EVs can be collected noninvasively (eg, blood) and impressively possess multilayered information, which is constituted by their concentration and molecular cargo. EV-based liquid biopsy may facilitate GBM diagnosis and enable the implementation of personalized treatment, resulting in customized care for each patient and for each analyzed time point of the disease, thereby tackling the distinctive heterogeneity and mutability of GBM that confounds effective treatment. Herein, we discuss the limitations of current GBM treatment options and the rationale behind the need for personalized care. We also review the evidence supporting GBM-associated EVs as a promising tool capable of fulfilling the still unmet clinical need for effective and timely personalized care of patients with GBM.

Revisiting the Immunological Aspects of Temozolomide Considering the Genetic Landscape and the Immune Microenvironment Composition of Glioblastoma

The microenvironment (ME) plays a critical role in causing glioblastoma (GBM) to be a moving and incurable target. The main features governing the interaction between cancer cells and the ME include dependency, promotion, and in rare cases, even competition. In the original Stupp protocol, the alkylating agent temozolomide (TMZ) is the first-line chemotherapy drug to treat GBM, and it is broadly used together or after radiotherapy. Some studies have described TMZ as an adjuvant to other therapeutic approaches including immunotherapy because of its ability to induce an immunogenic death of cancer cells. TMZ also exerts immunomodulatory effects on the tumor and immune ME. These findings support the coexistence of two circuits, i.e., one that subverts local immunosuppressive mechanisms and another that exerts a harmful influence on the peripheral immune response. A bias toward the latter can drive the failure of treatments based on the combination of chemotherapy and immunotherapy approaches. In this review, we will reanalyze how intrinsic and acquired resistance to TMZ impacts the immunomodulatory effects previously described by way of inducing a functional alteration of local immune cells and promoting immunosuppression and how different components of the immune ME, with particular attention to tumor-associated macrophages and microglia, can cause TMZ resistance to circumvent potential local immunogenic mechanisms.

The Interplay between Glioblastoma and Its Microenvironment

GBM is the most common primary brain tumor in adults, and the aggressive nature of this tumor contributes to its extremely poor prognosis. Over the years, the heterogeneous and adaptive nature of GBM has been highlighted as a major contributor to the poor efficacy of many treatments including various immunotherapies. The major challenge lies in understanding and manipulating the complex interplay among the different components within the tumor microenvironment (TME). This interplay varies not only by the type of cells interacting but also by their spatial distribution with the TME. This review highlights the various immune and non-immune components of the tumor microenvironment and their consequences f the efficacy of immunotherapies. Understanding the independent and interdependent aspects of the various sub-populations encapsulated by the immune and non-immune components will allow for more targeted therapies. Meanwhile, understanding how the TME creates and responds to different environmental pressures such as hypoxia may allow for other multimodal approaches in the treatment of GBM. Ultimately, a better understanding of the GBM TME will aid in the development and advancement of more effective treatments and in improving patient outcomes.

Microglia extracellular vesicles: focus on molecular composition and biological function

Extracellular vesicles (EVs) are a heterogeneous family of cell-derived lipid bounded vesicles comprising exosomes and microvesicles. They are potentially produced by all types of cells and are used as a cell-to-cell communication method that allows protein, lipid, and genetic material exchange. Microglia cells produce a large number of EVs both in resting and activated conditions, in the latter case changing their production and related biological effects. Several actions of microglia in the central nervous system are ascribed to EVs, but the molecular mechanisms by which each effect occurs are still largely unknown. Conflicting functions have been ascribed to microglia-derived EVs starting from the neuronal support and ending with the propagation of inflammation and neurodegeneration, confirming the crucial role of these organelles in tuning brain homeostasis. Despite the increasing number of studies reported on microglia-EVs, there is also a lot of fragmentation in the knowledge on the mechanism at the basis of their production and modification of their cargo. In this review, a collection of literature data about the surface and cargo proteins and lipids as well as the miRNA content of EVs produced by microglial cells has been reported. A special highlight was given to the works in which the EV molecular composition is linked to a precise biological function.

The 3.0 Cell Communication: New Insights in the Usefulness of Tunneling Nanotubes for Glioblastoma Treatment

Simple Summary

Communication between cells helps tumors acquire resistance to chemotherapy and makes the struggle against cancer more challenging. Tunneling nanotubes (TNTs) are long channels able to connect both nearby and distant cells, contributing to a more malignant phenotype. This finding might be useful in designing novel strategies of drug delivery exploiting these systems of connection. This would be particularly important to reach tumor niches, where glioblastoma stem cells proliferate and provoke immune escape, thereby increasing metastatic potential and tumor recurrence a few months after surgical resection of the primary mass. Along with the direct inhibition of TNT formation, TNT analysis, and targeting strategies might be useful in providing innovative tools for the treatment of this tumor.

Abstract

Glioblastoma (GBM) is a particularly challenging brain tumor characterized by a heterogeneous, complex, and multicellular microenvironment, which represents a strategic network for treatment escape. Furthermore, the presence of GBM stem cells (GSCs) seems to contribute to GBM recurrence after surgery, and chemo- and/or radiotherapy. In this context, intercellular communication modalities play key roles in driving GBM therapy resistance. The presence of tunneling nanotubes (TNTs), long membranous open-ended channels connecting distant cells, has been observed in several types of cancer, where they emerge to steer a more malignant phenotype. Here, we discuss the current knowledge about the formation of TNTs between different cellular types in the GBM microenvironment and their potential role in tumor progression and recurrence. Particularly, we highlight two prospective strategies targeting TNTs as possible therapeutics: (i) the inhibition of TNT formation and (ii) a boost in drug delivery between cells through these channels. The latter may require future studies to design drug delivery systems that are exchangeable through TNTs, thus allowing for access to distant tumor niches that are involved in tumor immune escape, maintenance of GSC plasticity, and increases in metastatic potential.

BICD Cargo Adaptor 1 (BICD1) Downregulation Correlates with a Decreased Level of PD-L1 and Predicts a Favorable Prognosis in Patients with IDH1-Mutant Lower-Grade Gliomas

Simple Summary

The hypoxic inducible factor 1A (HIF1A) pathway has been known to play an important role in tumor progression in various cancers, including lower-grade (Grade II/III) gliomas (LGGs). An in silico analysis using 34 genes associated with the activity of the HIF1A pathway demonstrated that the BICD cargo adaptor 1 (BICD1) gene is a potential prognostic marker in LGGs. Moreover, BICD1 gene (BICD1) expression was positively correlated with CD274, GSK3B, HGF, and STAT3 expression in LGGs. Importantly, BICD1 downregulation was significantly associated with well-known favorable prognostic markers, such as a higher Karnofsky performance score (KPS), IDH1/TP53/ATRX mutations, wild-type EGFR and younger patient age, in LGGs. Therefore, our findings present BICD1 as a new prognostic biomarker to more precisely predict the clinical outcomes of LGG patients in coordination with those well-known biomarkers.

Abstract

Although several biomarkers have been identified to predict the prognosis of lower-grade (Grade II/III) gliomas (LGGs), we still need to identify new markers to facilitate those well-known markers to obtain more accurate prognosis prediction in LGGs. Bioinformatics data from The Cancer Genome Atlas (TCGA), the Chinese Glioma Genome Atlas (CGGA), and the Cancer Cell Line Encyclopedia (CCLE) datasets were used as the research materials. In total, 34 genes associated with the HIF1A pathway were analyzed using the hierarchical method to search for the most compatible gene. The BICD cargo adaptor 1 (BICD1) gene (BICD1) was shown to be significantly correlated with The hypoxic inducible factor 1A (HIF1A) expression, the World Health Organization (WHO) grade, and IDH1 mutation status. In addition, BICD1 downregulation was significantly correlated with a higher Karnofsky performance score (KPS), IDH1/TP53/ATRX mutations, wild-type EGFR, and younger patient age in the enrolled LGG cohort. Moreover, BICD1 expression was significantly upregulated in wild-type IDH1 LGGs with EGFR mutations. Kaplan–Meier survival analysis revealed that BICD1 downregulation predicts a favorable overall survival (OS) in LGG patients, especially in those with IDH1 mutations. Intriguingly, we found a significant correlation between BICD1 downregulation and a decreased level of CD274, GSK3B, HGF, or STAT3 in LGGs. Our findings suggest that BICD1 downregulation could be a potential biomarker for a favorable prognosis of LGGs.

Molecular and Cellular Mechanisms of Glioblastoma

Glioblastoma is the most malignant primary brain tumor [...].

Effects of the DRD2/3 antagonist ONC201 and radiation in glioblastoma

BACKGROUND

Glioblastoma (GBM) is the deadliest of all brain cancers in adults. The current standard-of-care is surgery followed by radiotherapy and temozolomide, leading to a median survival time of only 15 months. GBM are organized hierarchically with a small number of glioma-initiating cells (GICs), responsible for therapy resistance and tumor recurrence, suggesting that targeting GICs could improve treatment response. ONC201 is a first-in-class anti-tumor agent with clinical efficacy in some forms of high-grade gliomas. Here we test its efficacy against GBM in combination with radiation.

METHODS

Using patient-derived GBM lines and mouse models of GBM we test the effects of radiation and ONC201 on GBM self-renewalin vitro and survivalin vivo.A possible resistance mechanism is investigated using RNA-Sequencing.

RESULTS

Treatment of GBM cells with ONC201 reduced self-renewal, clonogenicity and cell viabilityin vitro. ONC201 exhibited anti-tumor effects on radioresistant GBM cells indicated by reduced self-renewal in secondary and tertiary glioma spheres. Combined treatment of ONC201 and radiation prolonged survival in syngeneic and patient-derived orthotopic xenograft mouse models of GBM. Subsequent transcriptome analyses after combined treatment revealed shifts in gene expression signatures related to quiescent GBM populations, GBM plasticity, and GBM stem cells.

CONCLUSIONS

Our findings suggest that combined treatment with the DRD2/3 antagonist ONC201 and radiation improves the efficacy of radiation against GBMin vitroandin vivothrough suppression of GICs without increasing toxicity in mouse models of GBM. A clinical assessment of this novel combination therapy against GBM is further warranted.

The role of Exosomes in the Pathogenesis of Nasopharyngeal Carcinoma and the involved Clinical Application

Exosomes are nanoscale membrane vesicles, which carry biologically active substances of their cell of origin and play an important role in signal transduction and intercellular communication. At present, exosomes have been identified as a promising non-invasive liquid biopsy biomarker in the tissues and circulating blood of nasopharyngeal carcinoma (NPC) and found to participate in regulating pathophysiological process of the tumor. We here review recent insights gained into the molecular mechanisms of exosome-induced cell growth, angiogenesis, metastasis, immunosuppression, radiation resistance and chemotherapy resistance in the development and progression of NPC, as well as the clinical application of exosomes as diagnostic biomarkers and therapeutic agents. We also discuss the limitations and challenges in exosome application. We hope this review may provide some references for the use of exosomes in clinical intervention.

Clinical Implications of Exosomes: Targeted Drug Delivery for Cancer Treatment

Exosomes are nanoscale vesicles generated by cells for intercellular communication. Due to their composition, significant research has been conducted to transform these particles into specific delivery systems for various disease states. In this review, we discuss the common isolation and loading methods of exosomes, some of the major roles of exosomes in the tumor microenvironment, as well as discuss recent applications of exosomes as drug delivery vessels and the resulting clinical implications.

Warburg effect-promoted exosomal circ_0072083 releasing up-regulates NANGO expression through multiple pathways and enhances temozolomide resistance in glioma

Background

Temozolomide (TMZ) resistance limits its application in glioma. Exosome can carry circular RNAs (circRNAs) to regulate drug resistance via sponging microRNAs (miRNAs). miRNAs can control mRNA expression by regulate the interaction with 3’UTR and methylation. Nanog homeobox (NANOG) is an important biomarker for TMZ resistance. Hitherto, it is unknown about the role of exosomal hsa_circ_0072083 (circ_0072083) in TMZ resistance in glioma, and whether it is associated with NANOG via regulating miRNA sponge and methylation.

Methods

TMZ-resistant (n = 36) and sensitive (n = 33) patients were recruited. The sensitive cells and constructed resistant cells were cultured and exposed to TMZ. circ_0072083, miR-1252-5p, AlkB homolog H5 (ALKBH5) and NANOG levels were examined via quantitative reverse transcription polymerase chain reaction and western blot. The half maximal inhibitory concentration (IC50) of TMZ, cell proliferation, apoptosis, migration and invasion were analyzed via Cell Counting Kit-8, colony formation, flow cytometry, wound healing and transwell assays. The in vivo function was assessed using xenograft model. The N6-methyladenosine (m6A) level was analyzed via methylated RNA immunoprecipitation (MeRIP). Target relationship was investigated via dual-luciferase reporter assay and RNA immunoprecipitation. Warburg effect was investigated via lactate production, glucose uptake and key enzymes expression. Exosome was isolated and confirmed via transmission electron microscopy and specific protein expression.

Results

circ_0072083 expression was increased in TMZ-resistant glioma tissues and cells. circ_0072083 knockdown restrained the resistance of resistant cells via decreasing IC50 of TMZ, proliferation, migration, invasion and xenograft tumor growth and increasing apoptosis. circ_0072083 silence reduced NANOG expression via blocking ALKBH5-mediated demethylation. circ_0072083 could regulate NANOG and ALKBH5 via targeting miR-1252-5p to control TMZ resistance. Warburg effect promoted the release of exosomal circ_0072083 in resistant cells. Exosomal circ_0072083 from resistant cells increased the resistance of sensitive cells to TMZ in vitro and xenograft model. Exosomal circ_0072083 level was enhanced in resistant patients, and it had a diagnostic value and indicated a lower overall survival in glioma.

Conclusion

Exosomal circ_0072083 promoted TMZ resistance via increasing NANOG via regulating miR-1252-5p-mediated degradation and demethylation in glioma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01942-6.

Exosomes derived from microRNA-512-5p-transfected bone mesenchymal stem cells inhibit glioblastoma progression by targeting JAG1

In this study, we demonstrate that bone mesenchymal stem cell (BMSC)-derived exosomes alter tumor phenotypes by delivering miR-512-5p. miR-512-5p was downregulated in glioblastoma tissues and cells, and Jagged 1 (JAG1) was the target gene of miR-512-5p. We clarified the expression patterns of miR-512-5p and JAG1 along with their interactions in glioblastoma. Additionally, we observed that BMSC-derived exosomes could contain and transport miR-512-5p to glioblastoma cells in vitro. BMSC-derived exosomal miR-512-5p inhibited glioblastoma cell proliferation and induced cell cycle arrest by suppressing JAG1 expression. In vivo assays validated the in vitro findings, with BMSC-exosomal miR-512-5p inhibiting glioblastoma growth and prolonging survival in mice. These results suggest that BMSC-derived exosomes transport miR-512-5p into glioblastoma and slow its progression by targeting JAG1. This study reveals a new molecular mechanism for glioblastoma treatment and validates miRNA packaging into exosomes for glioblastoma cell communication.