Leukocytes as a reservoir of circulating oncogenic DNA and regulatory targets of tumor-derived extracellular vesicles

Utilizing Extracellular Vesicles for Eliminating 'Unwanted Molecules': Harnessing Nature's Structures in Modern Therapeutic Strategies

Extracellular vesicles (EVs) are small phospholipid bilayer-bond structures released by diverse cell types into the extracellular environment, maintaining homeostasis of the cell by balancing cellular stress. This article provides a comprehensive overview of extracellular vesicles, their heterogeneity, and diversified roles in cellular processes, emphasizing their importance in the elimination of unwanted molecules. They play a role in regulating oxidative stress, particularly by discarding oxidized toxic molecules. Furthermore, endoplasmic reticulum stress induces the release of EVs, contributing to distinct results, including autophagy or ER stress transmission to following cells. ER stress-induced autophagy is a part of unfolded protein response (UPR) and protects cells from ER stress-related apoptosis. Mitochondrial-derived vesicles (MDVs) also play a role in maintaining homeostasis, as they carry damaged mitochondrial components, thereby preventing inflammation. Moreover, EVs partake in regulating aging-related processes, and therefore they can potentially play a crucial role in anti-aging therapies, including the treatment of age-related diseases such as Alzheimer's disease or cardiovascular conditions. Overall, the purpose of this article is to provide a better understanding of EVs as significant mediators in both physiological and pathological processes, and to shed light on their potential for therapeutic interventions targeting EV-mediated pathways in various pathological conditions, with an emphasis on age-related diseases.

Exosomes in metastasis of colorectal cancers: Friends or foes?

Colorectal cancer (CRC), the third most common type of cancer worldwide, threaten human health and quality of life. With multidisciplinary, including surgery, chemotherapy and/or radiotherapy, patients with an early diagnosis of CRC can have a good prognosis. However, metastasis in CRC patients is the main risk factor causing cancer-related death. To elucidate the underlying molecular mechanisms of CRC metastasis is the difficult and research focus on the investigation of the CRC mechanism. On the other hand, the tumor microenvironment (TME) has been confirmed as having an essential role in the tumorigenesis and metastasis of malignancies, including CRCs. Among the different factors in the TME, exosomes as extracellular vesicles, function as bridges in the communication between cancer cells and different components of the TME to promote the progression and metastasis of CRC. MicroRNAs packaged in exosomes can be derived from different sources and transported into the TME to perform oncogenic or tumor-suppressor roles accordingly. This article focuses on CRC exosomes and illustrates their role in regulating the metastasis of CRC, especially through the packaging of miRNAs, to evoke exosomes as novel biomarkers for their impact on the metastasis of CRC progression.

Exosomes and circular RNAs: promising partners in hepatocellular carcinoma from bench to bedside

Hepatocellular carcinoma (HCC) is characterized by high morbidity and mortality, and a low 5-year survival rate. Exploring the potential molecular mechanisms, finding diagnostic biomarkers with high sensitivity and specificity, and determining new therapeutic targets for HCC are urgently needed. Circular RNAs (circRNAs) have been found to play a key role in the occurrence and development of HCC, while exosomes play an important role in intercellular communication; thus, the combination of circRNAs and exosomes may have inestimable potential in early diagnosis and curative therapy. Previous studies have shown that exosomes can transfer circRNAs from normal or abnormal cells to surrounding or distant cells; thereafter, circRNAs influence target cells. This review summarizes the recent progress regarding the roles of exosomal circRNAs in the diagnosis, prognosis, occurrence and development and immune checkpoint inhibitor and tyrosine kinase inhibitor resistance of HCC to provide inspiration for further research.

Biochemistry of exosomes and their theranostic potential in human diseases

Exosomes are classified as special extracellular vesicles in the eukaryotic system having diameters ranging from 30 to 120 nm. These vesicles carry various endogenous molecules including DNA, mRNA, microRNA, circular RNA, and proteins, crucial for numerous metabolic reactions and can be proposed as therapeutic or diagnostic targets for several disorders. The donor exosomes release their content to recipient cells and further establish the significant intercellular communication showing biological effects by triggering environmental alterations. Exosomes derived from mesenchymal and dendritic cells have demonstrated their therapeutic potential against organ injury. Yet, various intricacies are involved in exosomal transport and its inclusion in cancer and other disease pathogenesis needs to be explored. The exosomes represent profound potential as diagnostic biomarkers and therapeutic carriers in various pathophysiological conditions such as neurodegenerative diseases, chronic cancers, infectious diseases, female reproductive diseases and cardiovascular diseases. In the current study, we demonstrate the advancements in the implication of exosomes as one of the irrefutable prognostic biological targets in human health and diseases.

Heterogeneity of Extracellular Vesicles and Particles: Molecular Voxels in the Blood Borne "Hologram" of Organ Function, Disfunction and Cancer

Extracellular vesicles (EVs) and particles (EPs) serve as unique carriers of complex molecular information with increasingly recognized roles in health and disease. Individual EVs/EPs collectively contribute to the molecular fingerprint of their producing cell, reflecting its identity, state, function and phenotype. This property is of particular interest in cancer where enormous heterogeneity of cancer cells is compounded by the presence of altered stromal, vascular and immune cell populations, which is further complicated by systemic responses elicited by the disease in individual patients. These diverse and interacting cellular compartments are dynamically represented by myriads of EVs/EPs released into the circulating biofluids (blood) during cancer progression and treatment. Current approaches of liquid biopsy seek to follow specific elements of the EV/EP cargo that may have diagnostic utility (as biomarkers), such as cancer cell-derived mutant oncoproteins or nucleic acids. However, with emerging technologies enabling high-throughput EV/EP analysis at a single particle level, a more holistic approach may be on the horizon. Indeed, each EV/EP carries multidimensional information (molecular "voxel") that could be integrated across thousands of particles into a larger and unbiased landscape (EV/EP "hologram") reflecting the true cellular complexity of the disease, along with cellular interactions, systemic responses and effects of treatment. Thus, the longitudinal molecular mapping of EV/EP populations may add a new dimension to crucial aspects of cancer biology, personalized diagnostics, and therapy.

TP53 mutation detected in circulating exosomal DNA is associated with prognosis of patients with hepatocellular carcinoma

Exosome DNA (exoDNA) can be used for liquid biopsy. This study was the first to use droplet digital PCR (ddPCR) to detect tumor-specific mutations in exoDNA and to evaluate the prognosis of hepatocellular carcinoma (HCC) patients. 60 HCC patients were enrolled in the study. We used ddPCR to detect c.747 G > T mutation in TP53 gene. We analyzed the correlation between detectable mutation in exoDNA and clinicopathologic characteristics using Multivariate logistics regression analysis. We performed Cox regression to assess the correlation between mutation frequency (mutant droplets/total droplets, MD/TD) and prognostic. We found that 48 of 60 patients had c.747 G > T mutation in TP53 gene in exoDNA (80.0%). We found that detectable mutation in exoDNA and age were associated with microvascular invasion (MVI) (P < .01). The ROC curve analysis revealed that the best cutoff value of mutation frequency to predict MVI was 67% (sensitivity 48.15%, specificity 93.94%,), the corresponding AUC was 0.761 (95%CI, 0.640–0.866; P < .01). Furthermore, we found that patients suffered high-frequency mutation (>67%) had shorted median recurrence-free survival (RFS) with 63 days (range, 53–202 days), compared with 368 days (range, 51–576 days) for patients with low-frequency mutation (<67%) (HR:4.61; 95% CI, 1.70–12.48; P = 0 .003). We also found that high-frequency mutation was associated with poor prognosis though patients had better pathological characteristics, such as AFP (<400 ng/mL), Liver cirrhosis (Negative), Tumor thrombus (Negative), Tumor numbers (Single) and Post-operation TACE (Executed). We provided evidence that the mutations in exoDNA might be used to predict patients with poor RFS.

Abbreviations: TP53: Tumor protein p53; ExoDNA: Exosomal DNA; HCC: Hepatocellular carcinoma; ddPCR: Droplet digital Polymerase Chain Reaction (PCR); MD/TD: The ratio of mutant droplets/total droplets; AFP: Alpha-fetoprotein; MVI: Microvascular invasion; RFS: Recurrence-free survival.

Hypothesis: can transfer of primary neoplasm-derived extracellular vesicles and mitochondria contribute to the development of donor cell-derived hematologic neoplasms after allogeneic hematopoietic cell transplantation?

Allogeneic hematopoietic cell transplantation (allo-HCT) is an essential treatment option for various neoplastic and non-neoplastic hematologic diseases. Although its efficacy is modest, a significant proportion of patients experience relapse, graft-versus-host disease, infection or impaired hematopoiesis. Among these, the most frequent cause of post-transplant mortality is relapse, whereas the development of de novo hematologic neoplasms from donor cells after allo-HCT occurs on some occasion as a rare complication. The mechanisms involved in the pathogenesis of the de novo hematologic neoplasms from donor cells are complex, and a multifactorial process contributes to the development of this complication. Recently, extracellular vesicles, particularly exosomes, and mitochondria have been shown to play crucial roles in intercellular communication through the transfer of specific constituents, such as deoxyribonucleic acids, ribonucleic acids, lipids, metabolites and cytosolic and cell-surface proteins. Here, I discuss the potential causative roles of these subcellular components in the development of de novo hematologic neoplasms from donor cells after allo-HCT, in addition to other etiologies.

Role of extracellular vesicles in cancer-specific interactions between tumour cells and the vasculature

Cancer progression impacts and exploits the vascular system in several highly consequential ways. Among different types of vascular cells, blood cells and mediators that are engaged in these processes, endothelial cells are at the centre of the underlying circuitry, as crucial constituents of angiogenesis, angiocrine stimulation, non-angiogenic vascular growth, interactions with the coagulation system and other responses. Tumour-vascular interactions involve soluble factors, extracellular matrix molecules, cell-cell contacts, as well as extracellular vesicles (EVs) carrying assemblies of molecular effectors. Oncogenic mutations and transforming changes in the cancer cell genome, epigenome and signalling circuitry exert important and often cancer-specific influences upon pathways of tumour-vascular interactions, including the biogenesis, content, and biological activity of EVs and responses of cancer cells to them. Notably, EVs may carry and transfer bioactive, oncogenic macromolecules (oncoproteins, RNA, DNA) between tumour and vascular cells and thereby elicit unique functional changes and forms of vascular growth and remodeling. Cancer EVs influence the state of the vasculature both locally and systemically, as exemplified by cancer-associated thrombosis. EV-mediated communication pathways represent attractive targets for therapies aiming at modulation of the tumour-vascular interface (beyond angiogenesis) and could also be exploited for diagnostic purposes in cancer.

The Effect of Extracellular Vesicles on Thrombosis

The risk of cardiovascular events caused by acute thrombosis is high, including acute myocardial infarction, acute stroke, acute pulmonary embolism, and deep vein thrombosis. In this review, we summarize the roles of extracellular vesicles of different cellular origins in various cardiovascular events associated with acute thrombosis, as described in the current literature, to facilitate the future development of a precise therapy for thrombosis caused by such vesicles. We hope that our review will indicate a new horizon in the field of cardiovascular research with regard to the treatment of acute thrombosis, especially targeting thrombosis caused by extracellular vesicles secreted by individual cells. As more emerging technologies are being developed, new diagnostic and therapeutic strategies related to EVs are expected to be identified for related diseases in the future.

Tumor-derived extracellular vesicles modulate innate immune responses to affect tumor progression

Immune cells are capable of influencing tumor progression in the tumor microenvironment (TME). Meanwhile, one mechanism by which tumor modulate immune cells function is through extracellular vesicles (EVs), which are cell-derived extracellular membrane vesicles. EVs can act as mediators of intercellular communication and can deliver nucleic acids, proteins, lipids, and other signaling molecules between cells. In recent years, studies have found that EVs play a crucial role in the communication between tumor cells and immune cells. Innate immunity is the first-line response of the immune system against tumor progression. Therefore, tumor cell-derived EVs (TDEVs) which modulate the functional change of innate immune cells serve important functions in the context of tumor progression. Emerging evidence has shown that TDEVs dually enhance or suppress innate immunity through various pathways. This review aims to summarize the influence of TDEVs on macrophages, dendritic cells, neutrophils, and natural killer cells. We also summarize their further effects on the progression of tumors, which may provide new ideas for developing novel tumor therapies targeting EVs.

Targeting Endocytosis and Cell Communications in the Tumor Immune Microenvironment

The existence of multiple endocytic pathways is well known, and their exact biological effects in tumors have been intensively investigated. Endocytosis can affect the connection between tumor cells and determine the fate of tumor cells. Many relationships between endocytosis and tumor cells have been elucidated, but the mechanism of endocytosis between different types of cells in tumors needs to be explored in greater depth. Endocytic receptors sense the environment and are induced by specific ligands to trigger communication between tumor and immune cells. Crosstalk in the tumor microenvironment can occur through direct contact between cell adhesion molecules or indirectly through exosomes. So a better understanding of the endocytic pathways that control cell adhesion molecules and function is expected to lead to new candidates for cancer treatment. In additional, tumor-derived exosomes may changes immune cell function, which may be a key role for tumors to evade immune detection and response. The overall understanding of exosomes through endocytosis is also expected to bring new candidates for therapeutic regulation of tumor immune microenvironment. In this case, endocytic pathways coordinate cell adhesion molecules and exosomes and can be used as targets in the tumor immune microenvironment for cancer treatment.

The Significance of Neutrophil Extracellular Traps in Colorectal Cancer and Beyond: From Bench to Bedside

Neutrophil extracellular traps (NETs), products of neutrophil death when exposed to certain stimuli, were first proposed as a type of response to bacterial infection in infectious diseases. Since then, extensive studies have discovered its involvement in other non-infectious inflammatory diseases including thromboembolism, autoimmune diseases, and cancer. Colorectal cancer (CRC) is one of the most common malignancies in the world. NET formation is closely associated with tumorigenesis, progression, and metastasis in CRC. Therefore, the application of NETs in clinical practice as diagnostic biomarkers, therapeutic targets, and prognostic predictors has a promising prospect. In addition, therapeutics targeting NETs are significantly efficient in halting tumor progression in preclinical cancer models, which further indicates its potential clinical utility in cancer treatment. This review focuses on the stimuli of NETosis, its pro-tumorigenic activity, and prospective clinical utility primarily in but not limited to CRC.

Detection of Temozolomide-Induced Hypermutation and Response to PD-1 Checkpoint Inhibitor In Recurrent Glioblastoma

Background

Despite aggressive upfront treatment in glioblastoma (GBM), recurrence remains inevitable for most patients. Accumulating evidence has identified hypermutation induced by temozolomide (TMZ) as an emerging subtype of recurrent GBM. However, its biological and therapeutic significance has yet to be described.

Methods

We combined GBM patient and derive GBM stem cells (GSCs) from tumors following TMZ to explore response of hypermutant and non-hypermutant emergent phenotypes and explore the immune relevance of hypermutant and non-hypermutant states in vivo.

Results

Hypermutation emerges as one of two possible mutational subtypes following TMZ treatment in vivo and demonstrates distinct phenotypic features compared to non-hypermutant recurrent GBM. Hypermutant tumors elicited robust immune rejection in subcutaneous contexts which was accompanied by increased immune cell infiltration. In contrast, immune rejection of hypermutant tumors were stunted in orthotopic settings where we observe limited immune infiltration. Use of anti-PD-1 immunotherapy showed that immunosuppression in orthotopic contexts was independent from the PD-1/PD-L1 axis. Finally, we demonstrate that mutational burden can be estimated from DNA contained in extracellular vesicles (EVs).

Conclusion

Hypermutation post-TMZ are phenotypically distinct from non-hypermutant GBM and requires personalization for appropriate treatment. The brain microenvironment may be immunosuppressive and exploration of the mechanisms behind this may be key to improving immunotherapy response in this subtype of recurrent GBM.

Rational Development of Liquid Biopsy Analysis in Renal Cell Carcinoma

Simple Summary

Among patients affected by renal cell carcinoma (RCC), the most common type of kidney cancer, it remains difficult to identify those who are at high risk for relapse or metastasis. This is in part due to the absence of reliable clinical biomarkers and robust methods to capture them. The aim of our study was to develop an improved assay to capture prognostic genomic biomarkers in circulating tumor DNA (ctDNA) in RCC. For this purpose, we first established a next generation sequencing (NGS) assay, targeting genes that are tailored for RCC and that are largely excluded from commercially available assays. Next, we showed the reliable performance of this assay to detect prognostic gene mutations in tumor DNA isolated from plasma, and from extracellular vesicles. Thus, our study provides a resource to facilitate ctDNA analysis for precision medicine in RCC.

Abstract

Renal cell carcinoma (RCC) is known for its variable clinical behavior and outcome, including heterogeneity in developing relapse or metastasis. Recent data highlighted the potential of somatic mutations as promising biomarkers for risk stratification in RCC. Likewise, the analysis of circulating tumor DNA (ctDNA) for such informative somatic mutations (liquid biopsy) is considered an important advance for precision oncology in RCC, allowing to monitor molecular disease evolution in real time. However, our knowledge about the utility of ctDNA analysis in RCC is limited, in part due to the lack of RCC-appropriate assays for ctDNA analysis. Here, by interrogating different blood compartments in xenograft models, we identified plasma cell-free (cf) DNA and extracellular vesicles (ev) DNA enriched for RCC-associated ctDNA. Additionally, we developed sensitive targeted sequencing and bioinformatics workflows capable of detecting somatic mutations in RCC-relevant genes with allele frequencies ≥ 0.5%. Applying this assay to patient-matched tumor and liquid biopsies, we captured tumor mutations in cf- and ev-DNA fractions isolated from the blood, highlighting the potentials of both fractions for ctDNA analysis. Overall, our study presents an RCC-appropriate sequencing assay and workflow for ctDNA analysis and provides a proof of principle as to the feasibility of detecting tumor-specific mutations in liquid biopsy in RCC patients.

Emerging role of tumor-derived extracellular vesicles in T cell suppression and dysfunction in the tumor microenvironment

Immunotherapeutic drugs including immune checkpoint blockade antibodies have been approved to treat patients in many types of cancers. However, some patients have little or no reaction to the immunotherapy drugs. The mechanisms underlying resistance to tumor immunotherapy are complicated and involve multiple aspects, including tumor-intrinsic factors, formation of immunosuppressive microenvironment, and alteration of tumor and stromal cell metabolism in the tumor microenvironment. T cell is critical and participates in every aspect of antitumor response, and T cell dysfunction is a severe barrier for effective immunotherapy for cancer. Emerging evidence indicates that extracellular vesicles (EVs) secreted by tumor is one of the major factors that can induce T cell dysfunction. Tumor-derived EVs are widely distributed in serum, tissues, and the tumor microenvironment of patients with cancer, which serve as important communication vehicles for cancer cells. In addition, tumor-derived EVs can carry a variety of immune suppressive signals driving T cell dysfunction for tumor immunity. In this review, we explore the potential mechanisms employed by tumor-derived EVs to control T cell development and effector function within the tumor microenvironment. Especially, we focus on current understanding of how tumor-derived EVs molecularly and metabolically reprogram T cell fates and functions for tumor immunity. In addition, we discuss potential translations of targeting tumor-derived EVs to reconstitute suppressive tumor microenvironment or to develop antigen-based vaccines and drug delivery systems for cancer immunotherapy.

Blood cell-derived extracellular vesicles: diagnostic biomarkers and smart delivery systems

Extracellular vesicles (EVs) are released by most of the cells or tissues and act as nanocarriers to transfer nucleic acids, proteins, and lipids. The blood system is the most abundant source of extracellular vesicles for purification, and it has attracted considerable attention as a source of diagnostic biomarkers. Blood-derived extracellular vesicles, especially vesicles released from erythrocytes and platelets, are highly important in nanoplatform-based therapeutic interventions as potentially ideal drug delivery vehicles. We reviewed the latest research progress on the paracrine effects and biological functions of extracellular vesicles derived from erythrocytes, leukocytes, platelets, and plasma. From a clinical perspective, we summarize selected useful diagnostic biomarkers for therapeutic intervention and diagnosis. Especially, we describe and discuss the potential application of erythrocyte-derived extracellular vesicles as a new nano-delivery platform for the desired therapeutics. We suggest that blood-derived extracellular vesicles are an ideal nanoplatform for disease diagnosis and therapy.

Extracellular vesicles are the primary source of blood-borne tumour-derived mutant KRAS DNA early in pancreatic cancer

Up to now, the field of liquid biopsies has focused on circulating tumour DNA and cells, though extracellular vesicles (EVs) have been of increasing interest in recent years. Thus, reported sources of tumour-derived nucleic acids include leukocytes, platelets and apoptotic bodies (AB), as well as large (LEV) and small (SEV) EVs. Despite these competing claims, there has yet to be a standardized comparison of the tumour-derived DNA associated with different components of blood. To address this issue, we collected twenty-three blood samples from seventeen patients with pancreatic cancers of known mutant KRAS G12 genotype, and divided them into two groups based on the time of patient survival following sampling. After collecting red and white blood cells, we subjected 1 ml aliquots of platelet rich plasma to differential centrifugation in order to separate the platelets, ABs, LEVs, SEVs and soluble proteins (SP) present. We then confirmed the enrichment of specific blood components in each differential centrifugation fraction using electron microscopy, Western blotting, nanoparticle tracking analysis and bead-based multiplex flow cytometry assays. By targeting wild type and tumour-specific mutant KRAS alleles using digital PCR, we found that the levels of mutant KRAS DNA were highest in association with LEVs and SEVs early, and with SEVs and SP late in disease progression. Importantly, we established that SEVs were the most enriched in tumour-derived DNA throughout disease progression, and verified this association using size exclusion chromatography. This work provides important direction for the rapidly expanding field of liquid biopsies by supporting an increased focus on EVs as a source of tumour-derived DNA.

Small Extracellular Vesicles in the Development, Diagnosis, and Possible Therapeutic Application of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) persists among the most lethal and broad-spreading malignancies in China. The exosome is a kind of extracellular vesicle (EV) from about 30 to 200 nm in diameter, contributing to the transfer of specific functional molecules, such as metabolites, proteins, lipids, and nucleic acids. The paramount role of exosomes in the formation and development of ESCC, which relies on promoting intercellular communication in the tumor microenvironment (TME), is manifested with immense amounts. Tumor-derived exosomes (TDEs) participate in most hallmarks of ESCC, including tumorigenesis, invasion, angiogenesis, immunologic escape, metastasis, radioresistance, and chemoresistance. Published reports have delineated that exosome-encapsulated cargos like miRNAs may have utility in the diagnosis, as prognostic biomarkers, and in the treatment of ESCC. This review summarizes the function of exosomes in the neoplasia, progression, and metastasis of ESCC, which improves our understanding of the etiology and pathogenesis of ESCC, and presents a promising target for early diagnostics in ESCC. However, recent studies of exosomes in the treatment of ESCC are sparse. Thus, we introduce the advances in exosome-based methods and indicate the possible applications for ESCC therapy in the future.

Genetic and epigenetic regulation of cancer coagulome - lessons from heterogeneity of cancer cell populations

Cancer-associated thrombosis (CAT) is a morbid, potentially life threatening and biologically impactful paraneoplastic state. At least in part, CAT is likely driven by cancer-specific mechanisms the nature of which is still poorly understood, hampering diagnostic, prophylactic and therapeutic efforts. It is increasingly appreciated that cancer-specific drivers of CAT include a constellation of oncogenic mutations and their superimposed epigenetic states that shape the transcriptome, phenotype and secretome of cancer cell populations, including the repertoire of genes impacting the vascular and coagulation systems. High-grade brain tumours, such as glioblastoma multiforme (GBM) represent a paradigm of locally initiated haemostatic abnormalities that propagate systemically, likely through circulating mediators, such as extracellular vesicles and soluble factors. Reciprocally, CAT impacts the biology of cancer cells and may drive tumour evolution. The constituent, oncogene-transformed cancer cell populations form complex ecosystems, the intricate architecture of which has been recently revealed by single cell sequencing technologies. Amidst this phenotypic heterogeneity, several alternative pathways of CAT may exist both between and within individual tumours and their subtypes, including GBM. Indeed, different contributions of cells expressing key coagulant mediators, such as tissue factor, or podoplanin, have been identified in GBM subtypes driven by oncogenic mutations in EGFR, IDH1 and other transforming genes. Thus, a better understanding of cellular sources of CAT, including dominant cancer cell phenotypes and their dynamic shifts, may help design more personalised approaches to thrombosis in cancer patients to improve outcomes.

Cancer-Associated Thrombosis: Risk Factors, Molecular Mechanisms, Future Management

Venous thromboembolism (VTE) is a major health problem in patients with cancer. Cancer augments thrombosis and causes cancer-associated thrombosis (CAT) and vice versa thrombosis amplifies cancer progression, termed thrombosis-associated cancer (TAC). Risk factors that lead to CAT and TAC include cancer type, chemotherapy, radiotherapy, hormonal therapy, anti-angiogenesis therapy, surgery, or supportive therapy with hematopoietic growth factors. There are some other factors that have an effect on CAT and TAC such as tissue factor, neutrophil extracellular traps (NETs) released in response to cancer, cancer procoagulant, and cytokines. Oncogenes, estrogen hormone, and thyroid hormone with its integrin αvβ3 receptor promote angiogenesis. Lastly, patient-related factors can play a role in development of thrombosis in cancer. Low-molecular-weight heparin and direct oral anticoagulants (DOACs) are used in VTE prophylaxis and treatment rather than vitamin K antagonist. Now, there are new directions for potential management of VTE in patients with cancer such as euthyroid, blockade of thyroid hormone receptor on integrin αvβ3, sulfated non-anticoagulant heparin, inhibition of NETs and stratifying low and high-risk patients with significant bleeding problems with DOACs.

Oncogenic RAS drives the CRAF-dependent extracellular vesicle uptake mechanism coupled with metastasis

Oncogenic RAS impacts communication between cancer cells and their microenvironment, but it is unclear how this process influences cellular interactions with extracellular vesicles (EVs). This is important as intercellular EV trafficking plays a key role in cancer invasion and metastasis. Here we report that overexpression of mutant RAS drives the EV internalization switch from endocytosis (in non-transformed cells) to macropinocytosis (in cancer cells) resulting in enhanced EV uptake. This process depends on the surface proteoglycan, fibronectin and EV engulfment mechanism regulated by CRAF. Both mutant RAS and activated CRAF expression is associated with formation of membrane ruffles to which they colocalize along with actin, sodium-hydrogen exchangers (NHEs) and phosphorylated myosin phosphatase (pMYPT). RAS-transformed cells internalize EVs in the vicinity of ruffled structures followed by apparent trafficking to lysosome and degradation. NHE inhibitor (EIPA) suppresses RAS-driven EV uptake, along with adhesion-independent clonal growth and experimental metastasis in mice. Thus, EV uptake may represent a targetable step in progression of RAS-driven cancers.

Exosomes in Liquid Biopsy: The Nanometric World in the Pursuit of Precision Oncology

Among the different components that can be analyzed in liquid biopsy, the utility of exosomes is particularly promising because of their presence in all biological fluids and their potential for multicomponent analyses. Exosomes are extracellular vesicles with an average size of ~100 nm in diameter with an endosomal origin. All eukaryotic cells release exosomes as part of their active physiology. In an oncologic patient, up to 10% of all the circulating exosomes are estimated to be tumor-derived exosomes. Exosome content mirrors the features of its cell of origin in terms of DNA, RNA, lipids, metabolites, and cytosolic/cell-surface proteins. Due to their multifactorial content, exosomes constitute a unique tool to capture the complexity and enormous heterogeneity of cancer in a longitudinal manner. Due to molecular features such as high nucleic acid concentrations and elevated coverage of genomic driver gene sequences, exosomes will probably become the "gold standard" liquid biopsy analyte in the near future.

The Role of Tumor-Derived Exosomes in the Abscopal Effect and Immunotherapy

Exosomes are microvesicles that can be secreted by various cells and carry a variety of contents; thus, they play multiple biological functions. For instance, the tumor-derived exosomes (TEXs) have been proven to have the effect of immunostimulatory in addition to immunosuppression, making TEXs attractive in clinical immunotherapy and targeted therapy for cancer patients. In addition, TEXs as biomarkers have important clinical diagnostic and prognostic value. Recently, TEXs have been recognized to play important roles in the abscopal effect (AbE), a newly discovered mechanism by which the distant tumors are effectively targeted and repressed during immunotherapy and radiotherapy. Therefore, TEXs has demonstrated great clinical potential in the diagnosis, prognosis and treatment of cancer patients in the future. This review summarizes and discusses the role of TEXs in clinical therapy and their role in AbE in recent studies.

Selection of Fluorescent, Bioluminescent, and Radioactive Tracers to Accurately Reflect Extracellular Vesicle Biodistribution in Vivo

The ability to track extracellular vesicles (EVs) in vivo without influencing their biodistribution is a key requirement for their successful development as drug delivery vehicles and therapeutic agents. Here, we evaluated the effect of five different optical and nuclear tracers on the in vivo biodistribution of EVs. Expi293F EVs were labeled using either a noncovalent fluorescent dye DiR, or covalent modification with ¹¹¹indium-DTPA, or bioengineered with fluorescent (mCherry) or bioluminescent (Firefly and NanoLuc luciferase) proteins fused to the EV marker, CD63. To focus specifically on the effect of the tracer, we compared EVs derived from the same cell source and administered systemically by the same route and at equal dose into tumor-bearing BALB/c mice. ¹¹¹Indium and DiR were the most sensitive tracers for in vivo imaging of EVs, providing the most accurate quantification of vesicle biodistribution by ex vivo imaging of organs and analysis of tissue lysates. Specifically, NanoLuc fused to CD63 altered EV distribution, resulting in high accumulation in the lungs, demonstrating that genetic modification of EVs for tracking purposes may compromise their physiological biodistribution. Blood kinetic analysis revealed that EVs are rapidly cleared from the circulation with a half-life below 10 min. Our study demonstrates that radioactivity is the most accurate EV tracking approach for a complete quantitative biodistribution study including pharmacokinetic profiling. In conclusion, we provide a comprehensive comparison of fluorescent, bioluminescent, and radioactivity approaches, including dual labeling of EVs, to enable accurate spatiotemporal resolution of EV trafficking in mice, an essential step in developing EV therapeutics.

A Comprehensive Review on Factors Influences Biogenesis, Functions, Therapeutic and Clinical Implications of Exosomes

Exosomes are nanoscale-sized membrane vesicles secreted by almost all cell types into the extracellular environment upon fusion of multivesicular bodies and plasma membrane. Biogenesis of exosomes is a protein quality control mechanism, and once released, exosomes transmit signals to other cells. The applications of exosomes have increased immensely in biomedical fields owing to their cell-specific cargos that facilitate intercellular communications with neighboring cells through the transfer of biologically active compounds. The diverse constituents of exosomes reflect their cell of origin and their detection in biological fluids represents a diagnostic marker for various diseases. Exosome research is expanding rapidly due to the potential for clinical application to therapeutics and diagnosis. However, several aspects of exosome biology remain elusive. To discover the use of exosomes in the biomedical applications, we must better understand the basic molecular mechanisms underlying their biogenesis and function. In this comprehensive review, we describe factors involved in exosomes biogenesis and the role of exosomes in intercellular signaling and cell-cell communications, immune responses, cellular homeostasis, autophagy, and infectious diseases. In addition, we discuss the role of exosomes as diagnostic markers, and their therapeutic and clinical implications. Furthermore, we addressed the challenges and outstanding developments in exosome research, and discuss future perspectives.

The Significance of Exosomal RNAs in the Development, Diagnosis, and Treatment of Gastric Cancer

Gastric cancer (GC) is one of the most common malignancies in the world. Exosomes, a subset of extracellular vesicles with an average diameter of 100 nm, contain and transfer a variety of functional macromolecules such as proteins, lipids, and nucleic acids. A large number of studies indicated that exosomes can play a significant role in the initiation and development of GC via facilitating intercellular communication between gastric cancer cells and microenvironment. Exosomal RNAs, one of the key functional cargos, are involved in the pathogenesis, development, and metastasis of GC. In addition, recent studies elucidated that exosomal RNAs may serve as diagnostic and prognostic biomarkers or therapeutic targets for GC. In this review, we summarized the function of exosomal RNA in the tumorigenesis, progression, diagnosis, and treatment of GC, which may further unveil the functions of exosome and promote the potentially diagnostic and therapeutic application of exosomes in GC.

Tumor-Derived Extracellular Vesicles and the Immune System-Lessons From Immune-Competent Mouse-Tumor Models

Tumor-derived extracellular vesicles (TEVs) are important regulators of the immune response in cancer; however, most research so far has been carried out using cell culture systems. Immune-competent murine tumor models currently provide the best platform to assess proposed roles of TEVs using in vivo animal models and therefore are important for examining interactions between TEVs and the immune system. In this review, we present the current knowledge on TEVs using in vivo tumor-bearing animal models, with a focus on the role of TEVs in mediating crosstalk between tumor cells and both adaptive and innate immune cells. In particular, we address the question how animal models can clarify the reported heterogeneity of TEV effects in both anti-tumor responses and evasion of immune surveillance. The potential of TEVs in mediating direct antigen-presenting functions supports their potential as cancer vaccine therapeutics, therefore, we provide an overview of key findings of TEV trials that have the potential as novel immunotherapies, and shed light on challenges in the path toward the first in-human trials. We also highlight the important updates on the methods that continue to enhance the rigor and reproducibility of EV studies, particularly in functional animal models.

Endothelium-Derived Extracellular Vesicles Associate with Poor Prognosis in Metastatic Colorectal Cancer

Elevated, tumor-derived extracellular vesicle (tdEV) and circulating tumor cell (CTC) loads in metastatic cancer are associated with poor clinical outcome. Herein, we investigate whether endothelium-derived extracellular vesicles (edEVs) can be detected in the blood of metastatic colorectal cancer (mCRC) patients, and whether those vesicles associate with prognosis. The open-source ACCEPT (Automated CTC Classification, Enumeration, and Phenotyping) software was used to enumerate edEVs, tdEVs, and other objects from digitally stored CellSearch images acquired after CTC and circulating endothelial cell (CEC) enrichment from the blood of 395 mCRC patients before the initiation of a new therapy. Patients had participated in the prospective phase III CAIRO2 study. The presence of edEVs was found 5- to 10-fold higher than CECs. The hazard ratio (HR) (95% CI) of progression-free survival (PFS) for increased CTCs (≥3 in 7.5 mL), tdEVs (≥40 in 7.5 mL), and edEVs (≥287 in 4.0 mL.) was 1.4 (1.1-1.9), 2.0 (1.5-2.6), and 1.7 (1.2-2.5), respectively. The HR of Overall Survival (OS) for increased CTCs, tdEVs and edEVs was 2.2 (1.7-3.0), 2.7 (2.0-3.5), and 2.1 (1.5-2.8), respectively. There was no cut-off value for CECs, leading to a dichotomization of patients with a significant HR. Only tdEVs remained a significant predictor of OS in the final multivariable model.

The Influence of a Stressful Microenvironment on Tumor Exosomes: A Focus on the DNA Cargo

Exosomes secreted by tumor cells, through the transport of bioactive molecules, reprogram the surroundings, building a microenvironment to support the development of the tumor. The discovery that exosomes carry genomic DNA reflecting that of the tumor cell of origin has encouraged studies to use them as non-invasive biomarkers. The exosome-mediated transfer of oncogenes suggested a new mechanism of malignant transformation that could play a role in the formation of metastases. Several studies have examined the role of tumor exosomes on the modulation of the tumor microenvironment, but relatively few have been directed to assess how stressful stimuli can influence their production and cargo. Understanding the changes in exosome loads and the production pattern of the stressed tumor cell may uncover actionable mechanisms responsible for tumor progression.

Primary tumor and metastasis-sectioning the different steps of the metastatic cascade

Patients with lung cancer in the majority die of metastases. Treatment options include surgery, chemo- and radiotherapy, targeted therapy by tyrosine kinase inhibitors (TKIs), and immuno-oncologic treatment. Despite the success with these treatment options, cure of lung cancer is achieved in only a very small proportion of patients. In most patients’ recurrence and metastasis will occur, and finally kill the patient. Metastasis is a multistep procedure. It requires a change in adhesion of tumor cells for detachment from their neighboring cells. The next step is migration either as single cells [epithelial-mesenchymal transition (EMT)], or as cell clusters (hybrid-EMT or bulk migration). A combination of genetic changes is required to facilitate migration. Then tumor cells have to orient themselves along matrix proteins, detect oxygen concentrations, prevent attacks by immune cells, and induce a tumor-friendly switch of stroma cells (macrophages, myofibroblasts, etc.). Having entered the blood stream tumor cells need to adapt to shear stress, avoid being trapped by coagulation, but also use coagulation in small veins for adherence to endothelia, and express homing molecules for extravasation. Within a metastatic site, tumor cells need a well-prepared niche to establish a metastatic focus. Tumor cells again have to establish a vascular net for maintaining nutrition and oxygen supply, communicate with stroma cells, grow out and set further metastases. In this review the different steps will be discussed with a focus on pulmonary carcinomas. The vast amount of research manuscripts published so far are not easy to analyze: in most reports’ single steps of the metastatic cascade are interpreted as evidence for the whole process; for example, migration is interpreted as evidence for metastasis. In lung cancer most often latency periods are shorter, in between 1–5 years. In other cases, despite widespread migration occurs, tumor cells die within the circulation and do not reach a metastatic site. Therefore, migration is a requisite, but does not necessarily predict metastasis. The intention of this review is to point to these different aspects and hopefully provoke research directed into a more functional analysis of the metastatic process.

A Rosetta Stone for Breast Cancer: Prognostic Value and Dynamic Regulation of Neutrophil in Tumor Microenvironment

Increasing evidence has revealed that the initiation and progression of breast cancer are greatly affected by the immune environment. Neutrophils are the most abundant leucocytes in circulation and act as the spearhead in inflammation, including in breast cancer. Circulating neutrophils are closely related to the prognosis of breast cancer patients, and tumor-infiltrating neutrophils have varied functions at different stages of breast cancer, such as antitumor or tumor-promoting neutrophils, which are termed N1 and N2 neutrophils, respectively. In this review, we will discuss the utility of circulating neutrophils for predicting prognosis and therapeutic efficacy and the underlying mechanisms of their chemotaxis, the dynamic regulation of their antitumor or protumor functions and their different spatial distributions in tumor microenvironment. Finally, we also discuss the possibility of targeting neutrophils as a therapeutic strategy in breast cancer.

Extracellular vesicles from genetically unstable, oncogene-driven cancer cells trigger micronuclei formation in endothelial cells

Oncogenic transformation impacts cancer cell interactions with their stroma, including through formation of abnormal blood vessels. This influence is often attributed to angiogenic growth factors, either soluble, or associated with tumor cell-derived extracellular vesicles (EVs). Here we examine some of the cancer-specific components of EV-mediated tumor-vascular interactions, including the impact of genetic driver mutations and genetic instability. Cancer cells expressing mutant HRAS oncogene exhibit aberrations of chromatin architecture, aneuploidy, cytoplasmic chromatin deposition and formation of micronuclei with a non-random chromosome content. EVs released from such HRAS-driven cells carry genomic DNA, including oncogenic sequences, and transfer this material to endothelial cells while inducing abnormal formation of micronuclei, along with cell migration and proliferation. Micronuclei were also triggered following treatment with EVs derived from glioma cells (and stem cells) expressing EGFRvIII oncogene, and in both endothelial cells and astrocytes. EVs from HRAS and EGFRvIII-driven cancer cells carry 19 common proteins while EVs from indolent control cells exhibit more divergent proteomes. Immortalized endothelial cell lines with disrupted TP53 pathway were refractory to EV-mediated micronuclei induction. We suggest that oncogenic transformation and intercellular trafficking of cancer-derived EVs may contribute to pathological vascular responses in cancer due to intercellular transmission of genomic instability.

The biology function and biomedical applications of exosomes

The study of extracellular vesicles (EVs) has the potential to identify unknown cellular and molecular mechanisms in intercellular communication and in organ homeostasis and disease. Exosomes, with an average diameter of ~100 nanometers, are a subset of EVs. The biogenesis of exosomes involves their origin in endosomes, and subsequent interactions with other intracellular vesicles and organelles generate the final content of the exosomes. Their diverse constituents include nucleic acids, proteins, lipids, amino acids, and metabolites, which can reflect their cell of origin. In various diseases, exosomes offer a window into altered cellular or tissue states, and their detection in biological fluids potentially offers a multicomponent diagnostic readout. The efficient exchange of cellular components through exosomes can inform their applied use in designing exosome-based therapeutics.

Fluids and their mechanics in tumour transit: shaping metastasis

Metastasis is a dynamic succession of events involving the dissemination of tumour cells to distant sites within the body, ultimately reducing the survival of patients with cancer. To colonize distant organs and, therefore, systemically disseminate within the organism, cancer cells and associated factors exploit several bodily fluid systems, which provide a natural transportation route. Indeed, the flow mechanics of the blood and lymphatic circulatory systems can be co-opted to improve the efficiency of cancer cell transit from the primary tumour, extravasation and metastatic seeding. Flow rates, vessel size and shear stress can all influence the survival of cancer cells in the circulation and control organotropic seeding patterns. Thus, in addition to using these fluids as a means to travel throughout the body, cancer cells exploit the underlying physical forces within these fluids to successfully seed distant metastases. In this Review, we describe how circulating tumour cells and tumour-associated factors leverage bodily fluids, their underlying forces and imposed stresses during metastasis. As the contribution of bodily fluids and their mechanics raises interesting questions about the biology of the metastatic cascade, an improved understanding of this process might provide a new avenue for targeting cancer cells in transit.

Leukobiopsy - A Possible New Liquid Biopsy Platform for Detecting Oncogenic Mutations

Detection of unique oncogenic alterations encoded by the sequence or biochemical modification in cancer-associated transforming macromolecules has revolutionized diagnosis, classification and management of human cancers. While these signatures were traditionally regarded as largely intracellular and confined to the tumor mass, oncogenic mutations and actionable cancer-related molecular alterations can also be accessed remotely through their recovery from biofluids of either rare circulating tumor cells (CTCs), or of more abundant non-cellular carriers, such as extracellular vesicles (EVs), protein complexes, or cell-free tumor DNA (ctDNA). Tumor-related macromolecules may also accumulate in circulating platelets. Collectively, these approaches are known as liquid biopsy and hold promise as non-invasive, real-time opportunities to access to the evolving molecular landscape of human malignancies. More recently, a possibility of recovering cancer-specific DNA sequences from circulating leukocytes has also been postulated using experimental models. While it is often assumed that these and other liquid biopsy approaches rely on material passively shed from the tumor mass or its debris, recent evidence suggests that several regulated processes contribute to the abundance, nature, half-life, and turnover of different circulating cancer-related molecular signals. Moreover, many of these signals possess biological activity and may elicit local and systemic regulatory responses. Thus, a better understanding of the biology of liquid biopsy platforms and analytes may enable achieving improved performance of this promising and emerging diagnostic strategy in cancer.

Neutrophil extracellular traps in breast cancer and beyond: current perspectives on NET stimuli, thrombosis and metastasis, and clinical utility for diagnosis and treatment

The formation of neutrophil extracellular traps (NETs), known as NETosis, was first observed as a novel immune response to bacterial infection, but has since been found to occur abnormally in a variety of other inflammatory disease states including cancer. Breast cancer is the most commonly diagnosed malignancy in women. In breast cancer, NETosis has been linked to increased disease progression, metastasis, and complications such as venous thromboembolism. NET-targeted therapies have shown success in preclinical cancer models and may prove valuable clinical targets in slowing or halting tumor progression in breast cancer patients. We will briefly outline the mechanisms by which NETs may form in the tumor microenvironment and circulation, including the crosstalk between neutrophils, tumor cells, endothelial cells, and platelets as well as the role of cancer-associated extracellular vesicles in modulating neutrophil behavior and NET extrusion. The prognostic implications of cancer-associated NETosis will be explored in addition to development of novel therapeutics aimed at targeting NET interactions to improve outcomes in patients with breast cancer.

Mapping Subpopulations of Cancer Cell-Derived Extracellular Vesicles and Particles by Nano-Flow Cytometry

The elusive complexity of membranous extracellular vesicle (EV) and membrane-less extracellular particle (EP) populations released from various cellular sources contains clues as to their biological functions and diagnostic utility. In this study, we employed optimized multicolor nano-flow cytometry, structured illumination (SIM), and atomic force microscopy (AFM) to bridge sensitive detection at the single EV/EP level and high-throughput analysis of cancer cell secretomes. We applied these approaches to particles released from intact cells driven by several different transforming mechanisms or to cells under therapeutic stress imposed by pharmacological inhibition of their oncogenic drivers, such as epidermal growth factor receptor (EGFR). We demonstrate a highly heterogeneous distribution of biologically relevant elements of the EV/EP cargo, including oncoproteins (EGFR), clotting factors (tissue factor), pro-metastatic integrins (ITGA6, ITGA4), tetraspanins (CD63), and genomic DNA across the entire particulate secretome of cancer cells. We observed that targeting EGFR activity with irreversible kinase inhibitors (dacomitinib) triggers emission of DNA containing EP/EV subpopulations, including particles (chromatimeres) harboring both EGFR and DNase-resistant chromatin. While nano-flow cytometry enables quantification of these changes across the entire particular secretome, SIM reveals individual molecular topography of EV/EP subsets and AFM exposes some of their physical properties, including the presence of nanofilaments and other substructures. We describe differential uptake rates of distinct EV subsets, resulting in preferential internalization of exosome-like small EVs by cancer cells to the exclusion of larger EVs. Thus, our study illustrates the potential of nano-flow cytometry coupled with high-resolution microscopy to explore the cancer-related EV/EP landscape.

Resectable lung lesions malignancy assessment and cancer detection by ultra-deep sequencing of targeted gene mutations in plasma cell-free DNA

Background

Early detection of lung cancer to allow curative treatment remains challenging. Cell-free circulating tumour (ct) DNA (ctDNA) analysis may aid in malignancy assessment and early cancer diagnosis of lung nodules found in screening imagery.

Methods

The multicentre clinical study enrolled 192 patients with operable occupying lung diseases. Plasma ctDNA, white cell count genomic DNA (gDNA) and tumour tissue gDNA of each patient were analysed by ultra-deep sequencing to an average of 35 000× of the coding regions of 65 lung cancer-related genes.

Results

The cohort consists of a quarter of benign lung diseases and three quarters of cancer patients with all histopathology subtypes. 64% of the cancer patients are at stage I. Gene mutations detection in tissue gDNA and plasma ctDNA results in a sensitivity of 91% and specificity of 88%. When ctDNA assay was used as the test, the sensitivity was 69% and specificity 96%. As for the lung cancer patients, the assay detected 63%, 83%, 94% and 100%, for stages I, II, III and IV, respectively. In a linear discriminant analysis, combination of ctDNA, patient age and a panel of serum biomarkers boosted the overall sensitivity to 80% at a specificity of 99%. 29 out of the 65 genes harboured mutations in the patients with lung cancer with the largest number found in TP53 (30% plasma and 62% tumour tissue samples) and EGFR (20% and 40%, respectively).

Conclusion

Plasma ctDNA was analysed in lung nodule assessment and early cancer detection, while an algorithm combining clinical information enhanced the test performance.

Trial registration number

NCT03081741.

Extracellular vesicles in autoimmune vasculitis - Little dirts light the fire in blood vessels

Systemic vasculitis is diverse group of autoimmune disorders which are characterized by inflammation of blood vessel walls with deep aching and burning pain. Their underlying etiology and pathophysiology still remain poorly understood. Extracellular vesicles (EVs), including exosomes, microvesicles (MVs), and apoptotic bodies, are membrane vesicular structures that are released either during cell activation, or when cells undergo programmed cell death, including apoptosis, necroptosis, and pyroptosis. Although EVs were thought as cell dusts, but now they have been found to be potently active since they harbor bioactive molecules, such as proteins, lipids, nucleic acids, or multi-molecular complexes. EVs can serve as novel mediators for cell-to-cell communications by delivery bioactive molecules from their parental cells to the recipient cells. Earlier studies mainly focused on MVs budding from membrane surface. Recent studies demonstrated that EVs may also carry molecules from cytoplasm or even from nucleus of their parental cells, and these EVs may carry autoantigens and are important in vasculitis. EVs may play important roles in vasculitis through their potential pathogenic involvements in inflammation, autoimmune responses, procoagulation, endothelial dysfunction/damage, angiogenesis, and intimal hyperplasia. EVs have also been used as specific biomarkers for diagnostic use or disease severity monitoring. In this review, we have focused on the aspects of EV biology most relevant to the pathogenesis of vasculitis, discussed their perspective insights, and summarized the exist literature on EV relevant studies in vasculitis, therefore provides an integration of current knowledge regarding the novel role of EVs in systemic vasculitis.

Extracellular vesicles in the tumor microenvironment: old stories, but new tales

Mammalian cells synthesize and release heterogeneous extracellular vesicles (EVs) which can be generally recognized as subclasses including exosomes, microvesicles (MVs), and apoptotic bodies (ABs), each differing in their biogenesis, composition and biological functions from others. EVs can originate from normal or cancer cells, transfer bioactive cargoes to both adjacent and distant sites, and orchestrate multiple key pathophysiological events such as carcinogenesis and malignant progression. Emerging as key messengers that mediate intercellular communications, EVs are being paid substantial attention in various disciplines including but not limited to cancer biology and immunology. Increasing lines of research advances have revealed the critical role of EVs in the establishment and maintenance of the tumor microenvironment (TME), including sustaining cell proliferation, evading growth suppression, resisting cell death, acquiring genomic instability and reprogramming stromal cell lineages, together contributing to the generation of a functionally remodeled TME. In this article, we present updates on major topics that document how EVs are implicated in proliferative expansion of cancer cells, promotion of drug resistance, reprogramming of metabolic activity, enhancement of metastatic potential, induction of angiogenesis, and escape from immune surveillance. Appropriate and insightful understanding of EVs and their contribution to cancer progression can lead to new avenues in the prevention, diagnosis and treatment of human malignancies in future medicine.

Oncogenic Regulation of Extracellular Vesicle Proteome and Heterogeneity

Mutational and epigenetic driver events profoundly alter intercellular communication pathways in cancer. This effect includes deregulated release, molecular composition, and biological activity of extracellular vesicles (EVs), membranous cellular fragments ranging from a few microns to less than 100 nm in diameter and filled with bioactive molecular cargo (proteins, lipids, and nucleic acids). While EVs are usually classified on the basis of their physical properties and biogenetic mechanisms, recent analyses of their proteome suggest a larger than expected molecular diversity, a notion that is also supported by multicolour nano-flow cytometry and other emerging technology platforms designed to analyze single EVs. Both protein composition and EV diversity are markedly altered by oncogenic transformation, epithelial to mesenchymal transition, and differentiation of cancer stem cells. Interestingly, only a subset of EVs released from mutant cells may carry oncogenic proteins (e.g., EGFRvIII), hence, these EVs are often referred to as "oncosomes". Indeed, oncogenic transformation alters the repertoire of EV-associated proteins, increases the presence of pro-invasive cargo, and alters the composition of distinct EV populations. Molecular profiling of single EVs may reveal a more intricate effect of transforming events on the architecture of EV populations in cancer and shed new light on their biological role and diagnostic utility.

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

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