Exosomes maintain cellular homeostasis by excreting harmful DNA from cells. Nat Commun. 2017;8:15287. [PMID: 28508895 PMCID: PMC5440838 DOI: 10.1038/ncomms15287]

The Role of Extracellular Vesicles in Cancer: Cargo, Function, and Therapeutic Implications

Extracellular vesicles (EVs) are a heterogeneous collection of membrane-bound structures that play key roles in intercellular communication. EVs are potent regulators of tumorigenesis and function largely via the shuttling of cargo molecules (RNA, DNA, protein, etc.) among cancer cells and the cells of the tumor stroma. EV-based crosstalk can promote proliferation, shape the tumor microenvironment, enhance metastasis, and allow tumor cells to evade immune destruction. In many cases these functions have been linked to the presence of specific cargo molecules. Herein we will review various types of EV cargo molecule and their functional impacts in the context of oncology.

Extracellular self-DNA as a damage-associated molecular pattern (DAMP) that triggers self-specific immunity induction in plants

Mammals sense self or non-self extracellular or extranuclear DNA fragments (hereinafter collectively termed eDNA) as indicators of injury or infection and respond with immunity. We hypothesised that eDNA acts as a damage-associated molecular pattern (DAMP) also in plants and that it contributes to self versus non-self discrimination. Treating plants and suspension-cultured cells of common bean (Phaseolus vulgaris) with fragmented self eDNA (obtained from other plants of the same species) induced early, immunity-related signalling responses such as H₂O₂ generation and MAPK activation, decreased the infection by a bacterial pathogen (Pseudomonas syringae) and increased an indirect defence to herbivores (extrafloral nectar secretion). By contrast, non-self DNA (obtained from lima bean, Phaseolus lunatus, and Acacia farnesiana) had significantly lower or no detectable effects. Only fragments below a size of 700 bp were active, and treating the eDNA preparation DNAse abolished its inducing effects, whereas treatment with RNAse or proteinase had no detectable effect. These findings indicate that DNA fragments, rather than small RNAs, single nucleotides or proteins, accounted for the observed effects. We suggest that eDNA functions a DAMP in plants and that plants discriminate self from non-self at a species-specific level. The immune systems of plants and mammals share multiple central elements, but further work will be required to understand the mechanisms and the selective benefits of an immunity response that is triggered by eDNA in a species-specific manner.

Exosomes in cancer: Small transporters with big functions

Exosomes are nanosized membrane-bound vesicles containing abundant proteins, DNA, mRNA, and non-coding RNAs. Exosomes are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material. Increasing studies have shown that exosomes play an important role in tumour initiation, growth, progression, metastasis, drug resistance and immune escape. In this article, we review recent advances in the biology of exosomes. We elaborate the specific mechanism by which exosomes affect the communication between tumours and the microenvironment. Finally, we report that exosomes may provide promising biomarkers for cancer diagnosis and represent new targets for cancer therapy.

The three-dimensional organization of the genome in cellular senescence and age-associated diseases

Recent advances in genomics and imaging technologies have increased our ability to interrogate the 3D conformation of chromosomes and to better understand principles of organization and dynamics, as well as how their alteration can lead to disease. In this review we describe how these technologies have shed new light into the role of the 3D organization of the genome in defining cellular states in aging and age-associated diseases. We compare the genomic organization in cellular senescence and cancer, discuss the role of the lamina in maintaining the structural and functional integrity of the genome, and we highlight the recent findings on how this organization breaks down in disease states.

Exosomes in the Oncobiology, Diagnosis, and Therapy of Hepatic Carcinoma: A New Player of an Old Game

Exosomes are emerging as essential vehicles mediated cross-talk between different types of cells in tumor microenvironment. The extensive exploration of exosomes in hepatocellular carcinoma (HCC) enhances our comprehension of cancer biology referring to tumor growth, metastasis, immune evasion, and chemoresistance. Besides, the versatile roles of exosomes provide reasonable explanations for the propensity for liver metastasis of gastric cancer, pancreatic ductal adenocarcinoma, breast cancer, and colorectal cancer. The selective-enriched components, especially some specific proteins and noncoding RNAs in exosomes, have great potential as noninvasive biomarkers of HCC with high sensitivity and specificity. The characteristics of exosomes further inspire frontier research to interrupt intercellular malignant signals by controlling the biogenesis, release, or contents of exosomes.

Comparative proteomics of soluble factors secreted by human breast adipose tissue from tumor and normal breast

Tumor progression depends on the tumor-stroma interaction. In the breast, adipose tissue is the predominant stromal type. We have previously demonstrated that conditioned media (CMs) from explants of human adipose tissue of tumor breasts (hATT) increase proliferation and migration of breast cancer epithelial cells when compared to human adipose tissue from normal breasts (hATN). In this work, we aim to identify specific proteins and molecular/biological pathways associated with the secretion profile of hATT and hATN explants.

hATT-CMs and hATN-CMs were separated by SDS-PAGE and analyzed by means of two-dimensional nano-liquid chromatography-mass spectrometry. The data was analyzed using ProteoIQ and FunRich software. In addition, 42 cytokines from hATT-CMs and hATN-CMs were assayed by a protein antibody assay. Compared to hATN-CMs, hATT-CMs showed greater protein diversity. We found that hATT-CMs presented a greater amount of proteins related to complement system activity, metabolism and immune system, as well as proteins involved in a variety of biological processes such as signal transduction and cell communication. Specifically, apolipoprotein AI and AII, complement component 3, and vimentin and desmin were significantly increased in hATT-CMs versus hATN-CMs. Moreover, a multivariate discriminant analysis of the cytokines detected by the array showed that IL-6, MCP-2 and GRO cytokines were sufficient and necessary to differentiate hATT-CMs from hATN-CMs. This analysis also showed that the levels of these three cytokines, taken together, correlated with stage and histological grade of the tumor in the hATT-CMs group, and with body mass index in the hATN-CMs group.

Detection of exosome miRNAs using molecular beacons for diagnosing prostate cancer

Prostate cancer is the fifth leading cause of cancer-related deaths among males worldwide. However, the biomarker for diagnosing prostate cancer that is used currently has limitations that must be overcome. Recently, several studies have demonstrated that the cancer liquid biopsy can be implemented by using exosome miRNAs. However, the current methods for the detection of exosome miRNAs are time-consuming, expensive, and laborious. Thus, we investigated a novel method for diagnosing prostate cancer that involves the use of molecular beacons for the in situ detection of miRNAs in exosomes from prostate cancer cells. We chose miRNA-375 and miRNA-574-3p as the target miRNAs for prostate cancer, and these markers in exosomes produced by prostate cancer cells including DU145 and PC-3 were successfully detected using molecular beacons. High fluorescent signals were obtained from MB and miRNA hybridization in exosomes in a concentration-dependent manner. In addition, exosome miRNAs can be detected even in the presence of human urine, so this method can be applied directly using human urine to perform liquid biopsies for prostate cancer. Overall, the in situ detection of exosome miRNAs using molecular beacons can be developed as a simple, cost effective, and non-invasive liquid biopsy for diagnosing prostate cancer.

Transcriptome reprogramming by cancer exosomes: identification of novel molecular targets in matrix and immune modulation

BACKGROUND

Exosomes are extracellular vesicles released by almost all cell types, including cancer cells, into bodily fluids such as saliva, plasma, breast milk, semen, urine, cerebrospinal fluid, amniotic fluid, synovial fluid and sputum. Their key function being intercellular communication with both neighbouring as well as distant cells. Cancer exosomes have been shown to regulate organ-specific metastasis. However, little is known about the functional differences and molecular consequences of normal cells responding to exosomes derived from normal cells compared to those derived from cancer cells.

METHODS

Here, we characterised and compared the transcriptome profiles of primary human normal oral keratinocytes (HNOK) in response to exosomes isolated from either primary HNOK or head and neck squamous cell carcinoma (HNSCC) cell lines.

RESULTS

In recipient HNOK cells, we found that regardless of normal or cancer derived, exosomes altered molecular programmes involved in matrix modulation (MMP9), cytoskeletal remodelling (TUBB6, FEZ1, CCT6A), viral/dsRNA-induced interferon (OAS1, IFI6), anti-inflammatory (TSC22D3), deubiquitin (OTUD1), lipid metabolism and membrane trafficking (BBOX1, LRP11, RAB6A). Interestingly, cancer exosomes, but not normal exosomes, modulated expression of matrix remodelling (EFEMP1, DDK3, SPARC), cell cycle (EEF2K), membrane remodelling (LAMP2, SRPX), differentiation (SPRR2E), apoptosis (CTSC), transcription/translation (KLF6, PUS7). We have also identified CEP55 as a potential cancer exosomal marker.

CONCLUSIONS

In conclusion, both normal and cancer exosomes modulated unique gene expression pathways in normal recipient cells. Cancer cells may exploit exosomes to confer transcriptome reprogramming that leads to cancer-associated pathologies such as angiogenesis, immune evasion/modulation, cell fate alteration and metastasis. Molecular pathways and biomarkers identified in this study may be clinically exploitable for developing novel liquid-biopsy based diagnostics and immunotherapies.

Perspective: bidirectional exosomal transport between cancer stem cells and their fibroblast-rich microenvironment during metastasis formation

Carcinomas are complex structures composed of hierarchically organized distinct cell populations such as cancer stem cells and non-stem (bulk) cancer cells. Their genetic/epigenetic makeup and the dynamic interplay between the malignant cell populations and their stromal fibroblasts are important determinants of metastatic tumor invasion. Important mediators of these interactions are the small, membrane-enclosed extracellular vesicles, in particular exosomes. Both cancer cell and fibroblast-derived exosomes carry a set of regulatory molecules, including proteins and different species of RNA, which cooperatively support metastatic tumor spread. Here, we briefly overview potential links between cancer stem cells and the exosome-mediated fibroblast-enriched metastatic niche formation to discuss their role in the promotion of tumor growth and metastatic expansion in breast carcinoma models.

Stimulation of exosome release by extracellular DNA is conserved across multiple cell types

Exosomes are distinguished from other types of extracellular vesicles by their small and relatively uniform size (30-100 nm) and their composition which reflects their endo-lysosomal origin. Involvement of these extracellular organelles in intercellular communication and their implication in pathological conditions has fuelled intensive research on mammalian exosomes; however, currently, very little is known about exosomes in lower vertebrates. Here we show that, in primary cultures of head kidney leukocytes from Atlantic salmon (Salmo salar), phosphorothioate CpG oligodeoxynucleotides induce secretion of vesicles with characteristics very similar to these of mammalian exosomes. Further experiments revealed that the oligonucleotide-induced exosome secretion did not depend on the CpG motifs but it relied on the phosphorothioate modification of the internucleotide linkage. Exosome secretion was also induced by genomic bacterial and eukaryotic DNA in toll-like receptor 9-negative piscine and human cell lines demonstrating that this is a phylogenetically conserved phenomenon which does not depend on activation of immune signaling pathways. In addition to exosomes, stimulation with phosphorothioate oligonucleotides and genomic DNA induced secretion of LC3B-II, an autophagosome marker, which was associated with vesicles of diverse size and morphology, possibly derived from autophagosome-related intracellular compartments. Overall, this work reveals a previously unrecognized biological activity of phosphorothioate ODNs and genomic DNA - their capacity to induce secretion of exosomes and other types of extracellular vesicles. This finding might help shed light on the side effects of therapeutic phosphorothioate oligodeoxynucleotides and the biological activity of extracellular genomic DNA which is often upregulated in pathological conditions.

Senescent Microvesicles: A Novel Advance in Molecular Mechanisms of Atherosclerotic Calcification

Atherosclerosis, a chronic inflammatory disease that causes the most heart attacks and strokes in humans, is the leading cause of death in the developing world; its principal clinical manifestation is coronary artery disease. The development of atherosclerosis is attributed to the aging process itself (biological aging) and is also associated with the development of chronic diseases (premature aging). Both aging processes produce an increase in risk factors such as oxidative stress, endothelial dysfunction and proinflammatory cytokines (oxi-inflamm-aging) that might generate endothelial senescence associated with damage in the vascular system. Cellular senescence increases microvesicle release as carriers of molecular information, which contributes to the development and calcification of atherosclerotic plaque, as a final step in advanced atherosclerotic plaque formation. Consequently, this review aims to summarize the information gleaned to date from studies investigating how the senescent extracellular vesicles, by delivering biological signalling, contribute to atherosclerotic calcification.

Priming of dendritic cells by DNA-containing extracellular vesicles from activated T cells through antigen-driven contacts

Interaction of T cell with antigen-bearing dendritic cells (DC) results in T cell activation, but whether this interaction has physiological consequences on DC function is largely unexplored. Here we show that when antigen-bearing DCs contact T cells, DCs initiate anti-pathogenic programs. Signals of this interaction are transmitted from the T cell to the DC, through extracellular vesicles (EV) that contain genomic and mitochondrial DNA, to induce antiviral responses via the cGAS/STING cytosolic DNA-sensing pathway and expression of IRF3-dependent interferon regulated genes. Moreover, EV-treated DCs are more resistant to subsequent viral infections. In summary, our results show that T cells prime DCs through the transfer of exosomal DNA, supporting a specific role for antigen-dependent contacts in conferring protection to DCs against pathogen infection. The reciprocal communication between innate and adaptive immune cells thus allow efficacious responses to unknown threats.

Emerging roles of extracellular vesicles in cardiac repair and rejuvenation

Cell therapy has received significant attention as a therapeutic approach to restore cardiac function after myocardial infarction. Accumulating evidence supports that beneficial effects observed with cell therapy are due to paracrine secretion of multiple factors from transplanted cells, which alter the tissue microenvironment and orchestrate cardiac repair processes. Of these paracrine factors, extracellular vesicles (EVs) have emerged as a key effector of cell therapy. EVs regulate cellular function through the transfer of cargo, such as microRNAs and proteins, which act on multiple biological pathways within recipient cells. These discoveries have led to the development of cell-free therapies using EVs to improve cardiac repair after a myocardial infarction. Here, we present an overview of the current use of EVs to enhance cardiac repair after myocardial infarction. We also discuss the emerging use of EVs for rejuvenation-based therapies. Finally, future directions for the use of EVs as therapeutic agents for cardiac regenerative medicine are also discussed.

Antitumor effect of oncolytic virus and paclitaxel encapsulated in extracellular vesicles for lung cancer treatment

Standard of care for cancer is commonly a combination of surgery with radiotherapy or chemoradiotherapy. However, in some advanced cancer patients this approach might still remaininefficient and may cause many side effects, including severe complications and even death. Oncolytic viruses exhibit different anti-cancer mechanisms compared with conventional therapies, allowing the possibility for improved effect in cancer therapy. Chemotherapeutics combined with oncolytic viruses exhibit stronger cytotoxic responses and oncolysis. Here, we have investigated the systemic delivery of the oncolytic adenovirus and paclitaxel encapsulated in extracellular vesicles (EV) formulation that, in vitro, significantly increased the transduction ratio and the infectious titer when compared with the virus and paclitaxel alone. We demonstrated that the obtained EV formulation reduced the in vivo tumor growth in animal xenograft model of human lung cancer. Indeed, we found that combined treatment of oncolytic adenovirus and paclitaxel encapsulated in EV has enhanced anticancer effects both in vitro and in vivo in lung cancer models. Transcriptomic comparison carried out on the explanted xenografts from the different treatment groups revealed that only 5.3% of the differentially expressed genes were overlapping indicating that a de novo genetic program is triggered by the presence of the encapsulated paclitaxel: this novel genetic program might be responsible of the observed enhanced antitumor effect. Our work provides a promising approach combining anticancer drugs and viral therapies by intravenous EV delivery as a strategy for the lung cancer treatment.

Fed-EXosome: extracellular vesicles and cell-cell communication in metabolic regulation

Extracellular vesicles (EVs) have emerged as a novel messaging system of the organism, mediating cell-cell and interorgan communication. Through their content of proteins and nucleic acids, as well as membrane proteins and lipid species, EVs can interact with and modulate the function of their target cells. The regulation of whole-body metabolism requires cross-talk between key metabolic tissues including adipose tissue (AT), the liver and skeletal muscle. Furthermore, the regulation of nutrient/energy allocation during pregnancy requires co-ordinated communication between the foetus and metabolic organs of the mother. A growing body of evidence is suggesting that EVs play a role in communication between and within key metabolic organs, both physiologically during metabolic homoeostasis but also contributing to pathophysiology during metabolic dysregulation observed in metabolic diseases such as obesity and diabetes. As obesity and its associated metabolic complications are reaching epidemic proportions, characterization of EV-mediated communication between key metabolic tissues may offer important insights into the regulation of metabolic functions during disease and offer global therapeutic opportunities. Here, we focus on the role of EVs in metabolic regulation and, in particular, EV-mediated cross-talk between cells of the AT.

Exosomes in Severe Asthma: Update in Their Roles and Potential in Therapy

Exosomes are nanosized vesicles and have recently been recognized as important players in cell-to-cell communication. Exosomes contain different mediators such as proteins, nucleic acids (DNA, mRNA, miRNAs, and other ncRNAs), and lipid mediators and can shuttle their exosomal content to both neighboring and distal cells. Exosomes are very effective in orchestrating immune responses in the airways and all cell types can contribute to the systemic exosome pool. Intracellular communication between the broad range of cell types within the lung is crucial in disease emphasizing the importance of exosomes. In asthma, exosomes affect the inflammatory microenvironment which ultimately determines the development or alleviation of the pathological symptoms. Recent studies in this area have provided insight into the underlying mechanisms of disease and led to interest in using exosomes as potential novel therapeutic agents.

Cellular senescence: Immunosurveillance and future immunotherapy

In response to persistent DNA damage, induction into cell senescence promotes an immunogenic program which facilitates immune clearance of these damaged cells. Under physiological conditions, senescent cells can activate both innate and adaptive immune responses, functioning to maintain tissue homeostasis. In addition, emerging findings suggest that programmed induction of cell senescence may be important for regulating reproductive processes, partly facilitated by immune clearance. However, likely owing to ageing of the immune system, a failure to eliminate senescent cells can contribute to their persistence in tissues, leading to the development and progression of age-related diseases. Such immune failure may in part be due to activation of the senescence program in immune cells, leading to their dysfunction. Furthermore, senescent cells under certain biological contexts have been shown to instead promote immune suppression, a response that may reflect differences between an acute verses chronic senescent phenotype. In this review, we provide an overview of the research to date concerning senescence immunosurviellance, including a focused discussion on the mechanisms by which macrophages may recognise senescent cells. Senescence immunotherapy strategies as an alternative to senolytics for the removal of senescent cells will also be discussed.

Adiponectin/T-cadherin system enhances exosome biogenesis and decreases cellular ceramides by exosomal release

Adiponectin, an adipocyte-derived circulating protein, accumulates in vasculature, heart, and skeletal muscles through interaction with a unique glycosylphosphatidylinositol-anchored cadherin, T-cadherin. Recent studies have demonstrated that such accumulation is essential for adiponectin-mediated cardiovascular protection. Here, we demonstrate that the adiponectin/T-cadherin system enhances exosome biogenesis and secretion, leading to the decrease of cellular ceramides. Adiponectin accumulated inside multivesicular bodies, the site of exosome generation, in cultured cells and in vivo aorta, and also in exosomes in conditioned media and in blood, together with T-cadherin. The systemic level of exosomes in blood was significantly affected by adiponectin or T-cadherin in vivo. Adiponectin increased exosome biogenesis from the cells, dependently on T-cadherin, but not on AdipoR1 or AdipoR2. Such enhancement of exosome release accompanied the reduction of cellular ceramides through ceramide efflux in exosomes. Consistently, the ceramide reduction by adiponectin was found in aortas of WT mice treated with angiotensin II, but not in T-cadherin-knockout mice. Our findings provide insights into adiponectin/T-cadherin-mediated organ protection through exosome biogenesis and secretion.

Extracellular Vesicles: Packages Sent With Complement

Cells communicate with other cells in their microenvironment by transferring lipids, peptides, RNA, and sugars in extracellular vesicles (EVs), thereby also influencing recipient cell functions. Several studies indicate that these vesicles are involved in a variety of critical cellular processes including immune, metabolic, and coagulatory responses and are thereby associated with several inflammatory diseases. Furthermore, EVs also possess anti-inflammatory properties and contribute to immune regulation, thus encouraging an emerging interest in investigating and clarifying mechanistic links between EVs and innate immunity. Current studies indicate complex interactions of the complement system with EVs, with a dramatic influence on local and systemic inflammation. During inflammatory conditions with highly activated complement, including after severe tissue trauma and during sepsis, elevated numbers of EVs were found in the circulation of patients. There is increasing evidence that these shed vesicles contain key complement factors as well as complement regulators on their surface, affecting inflammation and the course of disease. Taken together, interaction of EVs regulates complement activity and contributes to the pro- and anti-inflammatory immune balance. However, the molecular mechanisms behind this interaction remain elusive and require further investigation. The aim of this review is to summarize the limited current knowledge on the crosstalk between complement and EVs. A further aspect is the clinical relevance of EVs with an emphasis on their capacity as potential therapeutic vehicles in the field of translational medicine.

Emerging roles of extracellular vesicles in cellular senescence and aging

Cellular senescence is a cellular program that prevents the proliferation of cells at risk of neoplastic transformation. On the other hand, age-related accumulation of senescent cells promotes aging at least partially due to the senescence-associated secretory phenotype, whereby cells secrete high levels of inflammatory cytokines, chemokines, and matrix metalloproteinases. Emerging evidence, however, indicates that extracellular vesicles (EVs) are important mediators of the effects of senescent cells on their microenvironment. Senescent cells secrete more EphA2 and DNA via EVs, which can promote cancer cell proliferation and inflammation, respectively. Extracellular vesicles secreted from DNA-damaged cells can also affect telomere regulation. Furthermore, it has now become clear that EVs actually play important roles in many aspects of aging. This review is intended to summarize these recent progresses, with emphasis on relationships between cellular senescence and EVs.

Downregulation of cytoplasmic DNases is implicated in cytoplasmic DNA accumulation and SASP in senescent cells

Accumulating evidence indicates that the senescence-associated secretory phenotype (SASP) contributes to many aspects of physiology and disease. Thus, controlling the SASP will have tremendous impacts on our health. However, our understanding of SASP regulation is far from complete. Here, we show that cytoplasmic accumulation of nuclear DNA plays key roles in the onset of SASP. Although both DNase2 and TREX1 rapidly remove the cytoplasmic DNA fragments emanating from the nucleus in pre-senescent cells, the expression of these DNases is downregulated in senescent cells, resulting in the cytoplasmic accumulation of nuclear DNA. This causes the aberrant activation of cGAS-STING cytoplasmic DNA sensors, provoking SASP through induction of interferon-β. Notably, the blockage of this pathway prevents SASP in senescent hepatic stellate cells, accompanied by a decline of obesity-associated hepatocellular carcinoma development in mice. These findings provide valuable new insights into the roles and mechanisms of SASP and possibilities for their control.

Activation of DNA damage response induces the acquisition of senescence-associated secretory phenotype (SASP) in senescent cells, but precise mechanisms remain unclear. Here, the authors show that the cytoplasmic accumulation of nuclear DNA activated cytoplasmic DNA sensors to provoke SASP.

Extracellular Vesicles: Multimodal Envoys in Neural Maintenance and Repair

The physiology of the central nervous system (CNS) is built on a foundation of connection, integration, and the exchange of complex information among brain cells. Emerging evidence indicates that extracellular vesicles (EVs) are key players in the intercellular communication that underlies physiological processes such as synaptic plasticity and the maintenance of myelination. Furthermore, upon injury to the CNS, EVs may propagate inflammation across the blood-brain barrier and beyond, and also appear to mediate neuroprotection and modulate regenerative processes. In neurodegenerative diseases, EVs may play roles in the formation, spreading, and clearance of toxic protein aggregates. Here, we discuss the physiological roles of EVs in the healthy and the diseased CNS, with a focus on recent findings and emerging concepts.

The emerging roles of exosomes in the modulation of immune responses in cancer

Exosomes are promising tools for improving cancer care, but conversely may also contribute to tumor progression. Here, we highlight recently discovered roles of exosomes in modulating immune responses in cancer, with emphasis on exosomal surface proteins and on RNA and DNA content. We also discuss how exosomes could be exploited as biomarkers and delivery vehicles in cancer therapy.

The Unforeseen Non-Coding RNAs in Head and Neck Cancer

Previously ignored non-coding RNAs (ncRNAs) have become the subject of many studies. However, there is an imbalance in the amount of consideration that ncRNAs are receiving. Some transcripts such as microRNAs (miRNAs) or small interfering RNAs (siRNAs) have gained much attention, but it is necessary to investigate other “pieces of the RNA puzzle”. These can offer a more complete view over normal and pathological cell behavior. The other ncRNA species are less studied, either due to their recent discovery, such as stable intronic sequence RNA (sisRNA), YRNA, miRNA-offset RNAs (moRNA), telomerase RNA component (TERC), natural antisense transcript (NAT), transcribed ultraconserved regions (T-UCR), and pseudogene transcript, or because they are still largely seen as non-coding transcripts with no relevance to pathogenesis. Moreover, some are still considered housekeeping RNAs, for instance small nucleolar RNAs (snoRNAs) and TERC. Our review summarizes the biogenesis, mechanism of action and potential role of less known ncRNAs in head and neck cancer, with a particular focus on the installment and progress for this particular cancer type.

Biogenesis and function of extracellular vesicles in cancer

Extracellular vesicles (EVs) are heterogeneous multi-signal messengers that support cancer growth and dissemination by mediating the tumor-stroma crosstalk. Exosomes are a subtype of EVs that originate from the limiting membrane of late endosomes, and as such contain information linked to both the intrinsic cell "state" and the extracellular signals cells received from their environment. Resolving the signals affecting exosome biogenesis, cargo sorting and release will increase our understanding of tumorigenesis. In this review we highlight key cell biological processes that couple exosome biogenesis to cargo sorting in cancer cells. Moreover, we discuss how the bidirectional communication between tumor and non-malignant cells affect cancer growth and metastatic behavior.

New Technologies for Analysis of Extracellular Vesicles

Extracellular vesicles (EVs) are diverse, nanoscale membrane vesicles actively released by cells. Similar-sized vesicles can be further classified (e.g., exosomes, microvesicles) based on their biogenesis, size, and biophysical properties. Although initially thought to be cellular debris, and thus under-appreciated, EVs are now increasingly recognized as important vehicles of intercellular communication and circulating biomarkers for disease diagnoses and prognosis. Despite their clinical potential, the lack of sensitive preparatory and analytical technologies for EVs poses a barrier to clinical translation. New analytical platforms including molecular ones are thus actively being developed to address these challenges. Recent advances in the field are expected to have far-reaching impact in both basic and translational studies. This article aims to present a comprehensive and critical overview of emerging analytical technologies for EV detection and their clinical applications.

Exosomal proteins as potential markers of tumor diagnosis

Liquid biopsy especially that of exosomes carries tumor-specific molecules and provides useful information during tumor development and progression in "real time." Exosomes are membrane-encapsulated vesicles, constantly released by multiple cells, including cancer cells, in large quantities, and are widely present in body fluids. Tumor exosomes can remodel a tumor-supportive microenvironment via cross-talk with target cells. Recent research has mainly focused on exosomal miRNAs and to a small degree on proteins. However, detecting the genome output (active proteins such as phosphoproteins) can provide more direct information about disease progression, such as in the early discovery and monitoring of cancers. This review highlights the unique features of exosomal proteins over traditional serological markers and summarizes their recent use in cancer diagnosis and prognosis. Furthermore, we describe the general protocols of research on exosome proteomics with an emphasis on their clinical use.

Extracellular vesicles or free circulating DNA: where to search for BRAF and cKIT mutations?

Clinical evidence in oncology argues for the advantages of performing molecular analysis of blood biomarkers to provide information about systemic changes and tumor heterogeneity. Whereas the diagnostic value of cell-free circulating DNA (fcDNA) has successfully been demonstrated in several studies, DNA enclosed in extracellular vesicles (EV) has only recently been described, and its potential diagnostic value is unclear. We established a protocol for separation of EV and fc fractions and tested for presence of mutant BRAFV600E mediating resistance to Vemurafenib and cKITD816V mediating resistance to Imatinib in blood of patients with melanoma and mastocytosis. Our results show that EV contain significantly higher amounts of total DNA as compared to the fc fraction. However, about ten-fold higher copy numbers of the wild type and mutant BRAF and cKIT were detected in the fcDNA fraction supporting its diagnostic value and pointing to differences in fc and EV DNA content.

Isolation and characterization of urinary extracellular vesicles: implications for biomarker discovery

Urine is a valuable diagnostic medium and, with the discovery of urinary extracellular vesicles, is viewed as a dynamic bioactive fluid. Extracellular vesicles are lipid-enclosed structures that can be classified into three categories: exosomes, microvesicles (or ectosomes) and apoptotic bodies. This classification is based on the mechanisms by which membrane vesicles are formed: fusion of multivesicular bodies with the plasma membranes (exosomes), budding of vesicles directly from the plasma membrane (microvesicles) or those shed from dying cells (apoptotic bodies). During their formation, urinary extracellular vesicles incorporate various cell-specific components (proteins, lipids and nucleic acids) that can be transferred to target cells. The rigour needed for comparative studies has fueled the search for optimal approaches for their isolation, purification, and characterization. RNA, the newest extracellular vesicle component to be discovered, has received substantial attention as an extracellular vesicle therapeutic, and compelling evidence suggests that ex vivo manipulation of microRNA composition may have uses in the treatment of kidney disorders. The results of these studies are building the case that urinary extracellular vesicles act as mediators of renal pathophysiology. As the field of extracellular vesicle studies is burgeoning, this Review focuses on primary data obtained from studies of human urine rather than on data from studies of laboratory animals or cultured immortalized cells.

Exosomal miR-126 as a circulating biomarker in non-small-cell lung cancer regulating cancer progression

Lung cancer is one of the leading causes of cancer-related deaths. It is diagnosed mostly at the locally advanced or metastatic stage. Recently, micro RNAs (miRs) and their distribution in circulation have been implicated in physiological and pathological processes. In this study, miR-126 was evaluated in serum, exosome and exosome-free serum fractions in non-small cell lung cancer (NSCLC) patients at early and advanced stages, and compared with healthy controls. Down-regulation of miR-126 was found in serum of advanced stage NSCLC patients. In healthy controls, circulating miR-126 was equally distributed between exosomes and exosome-free serum fractions. Conversely, in both early and advanced stage NSCLC patients, miR-126 was mainly present in exosomes. Different fractions of miR-126 in circulation may reflect different conditions during tumour formation. Incubation of exosomes from early and advanced NSCLC patients induced blood vessel formation and malignant transformation in human bronchial epithelial cells. On the other hand, exosome-enriched miR-126 from normal endothelial cells inhibited cell growth and induces loss of malignancy of NSCLC cells. These findings suggest a role of exo-miRs in the modulation of the NSCLC microenvironmental niche. Exosome-delivered miRs thus hold a substantial promise as a diagnostics biomarker as well as a personalized therapeutic modality.

Isolation and characterization of urinary extracellular vesicles: implications for biomarker discovery

Urine is a valuable diagnostic medium and, with the discovery of urinary extracellular vesicles, is viewed as a dynamic bioactive fluid. Extracellular vesicles are lipid-enclosed structures that can be classified into three categories: exosomes, microvesicles (or ectosomes) and apoptotic bodies. This classification is based on the mechanisms by which membrane vesicles are formed: fusion of multivesicular bodies with the plasma membranes (exosomes), budding of vesicles directly from the plasma membrane (microvesicles) or those shed from dying cells (apoptotic bodies). During their formation, urinary extracellular vesicles incorporate various cell-specific components (proteins, lipids and nucleic acids) that can be transferred to target cells. The rigour needed for comparative studies has fueled the search for optimal approaches for their isolation, purification, and characterization. RNA, the newest extracellular vesicle component to be discovered, has received substantial attention as an extracellular vesicle therapeutic, and compelling evidence suggests that ex vivo manipulation of microRNA composition may have uses in the treatment of kidney disorders. The results of these studies are building the case that urinary extracellular vesicles act as mediators of renal pathophysiology. As the field of extracellular vesicle studies is burgeoning, this Review focuses on primary data obtained from studies of human urine rather than on data from studies of laboratory animals or cultured immortalized cells.

Extracellular Vesicles, Tunneling Nanotubes, and Cellular Interplay: Synergies and Missing Links

The process of intercellular communication seems to have been a highly conserved evolutionary process. Higher eukaryotes use several means of intercellular communication to address both the changing physiological demands of the body and to fight against diseases. In recent years, there has been an increasing interest in understanding how cell-derived nanovesicles, known as extracellular vesicles (EVs), can function as normal paracrine mediators of intercellular communication, but can also elicit disease progression and may be used for innovative therapies. Over the last decade, a large body of evidence has accumulated to show that cells use cytoplasmic extensions comprising open-ended channels called tunneling nanotubes (TNTs) to connect cells at a long distance and facilitate the exchange of cytoplasmic material. TNTs are a different means of communication to classical gap junctions or cell fusions; since they are characterized by long distance bridging that transfers cytoplasmic organelles and intracellular vesicles between cells and represent the process of heteroplasmy. The role of EVs in cell communication is relatively well-understood, but how TNTs fit into this process is just emerging. The aim of this review is to describe the relationship between TNTs and EVs, and to discuss the synergies between these two crucial processes in the context of normal cellular cross-talk, physiological roles, modulation of immune responses, development of diseases, and their combinatory effects in tissue repair. At the present time this review appears to be the first summary of the implications of the overlapping roles of TNTs and EVs. We believe that a better appreciation of these parallel processes will improve our understanding on how these nanoscale conduits can be utilized as novel tools for targeted therapies.

Exosomes: A Rising Star in Falling Hearts

Although exosomes were previously recognized as a mechanism for discharging useless cellular components, growing evidence has elucidated their roles in conveying information between cells. They contribute to cell-cell communication by carrying nucleic acids, proteins and lipids that can, in turn, regulate behavior of the target cells. Recent research suggested that exosomes extensively participate in progression of diverse cardiovascular diseases (CVDs), such as myocardial infarction, cardiomyopathy, pulmonary arterial hypertension and others. Here, we summarize effects of exosome-derived molecules (mainly microRNAs and proteins) on cardiac function, to examine their potential applications as biomarkers or therapeutics in CVDs.