Energy-requiring uptake of prostasomes and PC3 cell-derived exosomes into non-malignant and malignant cells

Increased levels of thymidine kinase 1 in malignant cell-derived extracellular vesicles

Extracellular vesicles (EVs), whose main subtypes are exosomes, microparticles, and apoptotic bodies, are secreted by all cells and harbor biomolecules such as DNA, RNA, and proteins. They function as intercellular messengers and, depending on their cargo, may have multiple roles in cancer development. Thymidine kinase 1 (TK1) is a cell cycle-dependent enzyme used as a biomarker for cell proliferation. TK1 is usually elevated in cancer patients' serum, making the enzyme a valuable tumor proliferation biomarker that strongly correlates with cancer stage and metastatic capabilities. Here, we investigated the presence of TK1 in EVs derived from three prostate cancer cell lines with various p53 mutation statuses (LNCaP, PC3, and DU145), EVs from the normal prostate epithelial cell line RWPE-1 and EVs isolated from human seminal fluid (prostasomes). We measured the TK1 activity by a real-time assay for these EVs. We demonstrated that the TK1 enzyme activity is higher in EVs derived from the malignant cell lines, with the highest activity from cells deriving from the most aggressive cancer, compared to the prostasomes and RWPE-1 EVs. The measurement of TK1 activity in EVs may be essential in future prostate cancer studies.

Characterization of spinal cord tissue-derived extracellular vesicles in neuroinflammation

Extracellular vesicles (EVs) are released by all cells, can cross the blood-brain barrier, and have been shown to play an important role in cellular communication, substance shuttling, and immune modulation. In recent years EVs have shifted into focus in multiple sclerosis (MS) research as potential plasma biomarkers and therapeutic vehicles. Yet little is known about the disease-associated changes in EVs in the central nervous system (CNS). To address this gap, we characterized the physical and proteomic changes of mouse spinal cord-derived EVs before and at 16 and 25 days after the induction of experimental autoimmune encephalomyelitis (EAE), a neuroinflammatory model of MS. Using various bioinformatic tools, we found changes in inflammatory, glial, and synaptic proteins and pathways, as well as a shift in the predicted contribution of immune and glial cell types over time. These results show that EVs provide snapshots of crucial disease processes such as CNS-compartmentalized inflammation, re/de-myelination, and synaptic pathology, and might also mediate these processes. Additionally, inflammatory plasma EV biomarkers previously identified in people with MS were also altered in EAE spinal cord EVs, suggesting commonalities of EV-related pathological processes during EAE and MS and overlap of EV proteomic changes between CNS and circulating EVs.

Immersed in a reservoir of potential: amniotic fluid-derived extracellular vesicles

This review aims to encapsulate the current knowledge in extracellular vesicles extracted from amniotic fluid and amniotic fluid derived stem/stromal cells. Amniotic fluid (AF) bathes the developing fetus, providing nutrients and protection from biological and mechanical dangers. In addition to containing a myriad of proteins, immunoglobulins and growth factors, AF is a rich source of extracellular vesicles (EVs). These vesicles originate from cells in the fetoplacental unit. They are biological messengers carrying an active cargo enveloped within the lipid bilayer. EVs in reproduction are known to play key roles in all stages of pregnancy, starting from fertilisation through to parturition. The intriguing biology of AF-derived EVs (AF-EVs) in pregnancy and their untapped potential as biomarkers is currently gaining attention. EV studies in numerous animal and human disease models have raised expectations of their utility as therapeutics. Amniotic fluid stem cell and mesenchymal stromal cell-derived EVs (AFSC-EVs) provide an established supply of laboratory-made EVs. This cell-free mode of therapy is popular as an alternative to stem cell therapy, revealing similar, if not better therapeutic outcomes. Research has demonstrated the successful application of AF-EVs and AFSC-EVs in therapy, harnessing their anti-inflammatory, angiogenic and regenerative properties. This review provides an overview of such studies and discusses concerns in this emerging field of research.

Exosomes as Theranostic Agents in Reproduction System

Exosomes (Exos), belonging to extracellular vesicles, are cell-derived nano-sized vesicles with the potential to carry different kinds of biological molecules. Many studies have proved the impacts of exosomal cargo on several biological processes in female and male reproductive systems. It is also hypothesized that changes in exosomal cargo are integral to the promotion of certain pathological conditions, thus Exos can be used as valid biomarkers for the diagnosis of infertility and other abnormal conditions. Here, efforts are made to collect some recent data related to the physiological significance of Exos in the reproductive system, and their potential therapeutic effects. It is anticipated that the current review article will lay the groundwork for elucidating the source and mechanisms by which Exos control the reproductive system additionally supplying fresh methods and concepts for the detection and treatment of disorders associated with fertility for future studies.

The multifaceted role of extracellular ATP in sperm function: From spermatogenesis to fertilization

Extracellular adenosine 5'-triphosphate (ATP) is a vital signaling molecule involved in various physiological processes within the body. In recent years, studies have revealed its significant role in male reproduction, particularly in sperm function. This review explores the multifaceted role of extracellular ATP in sperm function, from spermatogenesis to fertilization. We discuss the impact of extracellular ATP on spermatogenesis, sperm maturation and sperm-egg fusion, highlighting the complex regulatory mechanisms and potential clinical applications in the context of male infertility. By examining the latest research, we emphasize the crucial role of extracellular ATP in sperm function and propose future research directions to further.

Prostate cancer-derived small extracellular vesicle proteins: the hope in diagnosis, prognosis, and therapeutics

Current diagnostic tools for prostate cancer (PCa) diagnosis and risk stratification are insufficient. The hidden onset and poor efficacy of traditional therapies against metastatic PCa make this disease a heavy burden in global men's health. Prostate cancer-derived extracellular vesicles (PCDEVs) have garnered attention in recent years due to their important role in communications in tumor microenvironment. Recent advancements have demonstrated PCDEVs proteins play an important role in PCa invasion, progression, metastasis, therapeutic resistance, and immune escape. In this review, we briefly discuss the applications of sEV proteins in PCa diagnosis and prognosis in liquid biopsy, focus on the roles of the PCa-derived small EVs (sEVs) proteins in tumor microenvironment associated with cancer progression, and explore the therapeutic potential of sEV proteins applied for future metastatic PCa therapy.

Extracellular vesicle-based liquid biopsy biomarkers and their application in precision immuno-oncology

While the field of precision oncology is rapidly expanding and more targeted options are revolutionizing cancer treatment paradigms, therapeutic resistance particularly to immunotherapy remains a pressing challenge. This can be largely attributed to the dynamic tumor-stroma interactions that continuously alter the microenvironment. While to date most advancements have been made through examining the clinical utility of tissue-based biomarkers, their invasive nature and lack of a holistic representation of the evolving disease in a real-time manner could result in suboptimal treatment decisions. Thus, using minimally-invasive approaches to identify biomarkers that predict and monitor treatment response as well as alert to the emergence of recurrences is of a critical need. Currently, research efforts are shifting towards developing liquid biopsy-based biomarkers obtained from patients over the course of disease. Liquid biopsy represents a unique opportunity to monitor intercellular communication within the tumor microenvironment which could occur through the exchange of extracellular vesicles (EVs). EVs are lipid bilayer membrane nanoscale vesicles which transfer a plethora of biomolecules that mediate intercellular crosstalk, shape the tumor microenvironment, and modify drug response. The capture of EVs using innovative approaches, such as microfluidics, magnetic beads, and aptamers, allow their analysis via high throughput multi-omics techniques and facilitate their use for biomarker discovery. Artificial intelligence, using machine and deep learning algorithms, is advancing multi-omics analyses to uncover candidate biomarkers and predictive signatures that are key for translation into clinical trials. With the increasing recognition of the role of EVs in mediating immune evasion and as a valuable biomarker source, these real-time snapshots of cellular communication are promising to become an important tool in the field of precision oncology and spur the recognition of strategies to block resistance to immunotherapy. In this review, we discuss the emerging role of EVs in biomarker research describing current advances in their isolation and analysis techniques as well as their function as mediators in the tumor microenvironment. We also highlight recent lung cancer and melanoma studies that point towards their application as predictive biomarkers for immunotherapy and their potential clinical use in precision immuno-oncology.

Extracellular vesicles and particles as mediators of long-range communication in cancer: connecting biological function to clinical applications

Over the past decade, extracellular vesicles and particles (EVPs) have emerged as critical mediators of intercellular communication, participating in numerous physiological and pathological processes. In the context of cancer, EVPs exert local effects, such as increased invasiveness, motility, and reprogramming of tumor stroma, as well as systemic effects, including pre-metastatic niche formation, determining organotropism, promoting metastasis and altering the homeostasis of various organs and systems, such as the liver, muscle, and circulatory system. This review provides an overview of the critical advances in EVP research during the past decade, highlighting the heterogeneity of EVPs, their roles in intercellular communication, cancer progression, and metastasis. Moreover, the clinical potential of systemic EVPs as useful cancer biomarkers and therapeutic agents is explored. Last but not least, the progress in EVP analysis technologies that have facilitated these discoveries is discussed, which may further propel EVP research in the future.

Biogenesis, Isolation, and Detection of Exosomes and Their Potential in Therapeutics and Diagnostics

The increasing research and rapid developments in the field of exosomes provide insights into their role and significance in human health. Exosomes derived from various sources, such as mesenchymal stem cells, cardiac cells, and tumor cells, to name a few, can be potential therapeutic agents for the treatment of diseases and could also serve as biomarkers for the early detection of diseases. Cellular components of exosomes, several proteins, lipids, and miRNAs hold promise as novel biomarkers for the detection of various diseases. The structure of exosomes enables them as drug delivery vehicles. Since exosomes exhibit potential therapeutic applications, their efficient isolation from complex biological/clinical samples and precise real-time analysis becomes significant. With the advent of microfluidics, nano-biosensors are being designed to capture exosomes efficiently and rapidly. Herein, we have summarized the history, biogenesis, characteristics, functions, and applications of exosomes, along with the isolation, detection, and quantification techniques. The implications of surface modifications to enhance specificity have been outlined. The review also sheds light on the engineered nanoplatforms being developed for exosome detection and capture.

Exosomes released from cisplatin-resistant ovarian cancer cells modulate the reprogramming of cells in tumor microenvironments toward the cancerous cells

Exosomes released from cancer cells are involved in the reorganization of the tumor microenvironment which is the essential aspect of cancer pathogenesis. The intercommunications between cancer cells and diverse cell types in the microenvironment are accomplished by exosomes in ovarian cancer. Internalization pathway, intracellular fate, and biological functions in recipient cells mediated by exosomes released from cisplatin-resistant A2780cis have been studied. Also, histopathological evaluation of tumor, ovary, liver tissues and lymph nodes in vivo studies have been performed. The recipient cells internalized the exosomes via active uptake mechanisms, as shown by confocal microscopy. However, inhibitor studies and flow cytometry analysis showed that each recipient cell line used different uptake pathways. Also, confocal microscopy imaging indicated that the internalized exosomes trapped in the endosomes or phagosomes were distributed to the different cellular compartments including ER, Golgi, and lysosome. The transfer of exosomal oncogenic cargo into the cells modified the intracellular signaling of recipient cells including invasion and metastasis by Boyden-Chamber assay, proliferation by ATP analysis, epithelial-mesenchymal transition (EMT) markers at protein and mRNA levels by western blotting and real-time PCR, and protein kinases in the phospho-kinase array. This remodeling contributed to the initiation of carcinogenesis in ovarian epithelial and peritoneal mesothelial cells, and the progression of carcinogenesis in ovarian cancer cells. In addition, intraperitoneal tumor model studies show that exosomes released from cisplatin-resistant A2780cis cells may play role in the enlargement of lymph nodes, and tumor formations integrated with the liver, attached to the stomach and in the ovarian tissues.

Lactoferrin perturbs intracellular trafficking, disrupts cholesterol-rich lipid rafts and inhibits glycolysis of highly metastatic cancer cells harbouring plasmalemmal V-ATPase

The milk-derived bovine lactoferrin (bLf) is an iron-binding glycoprotein with remarkable selective anticancer activity towards highly metastatic cancer cells displaying the proton pump V-ATPase at the plasma membrane. As studies aiming to dissect the bLf mechanisms of action are critical to improve its efficacy and boost its targeted clinical use, herein we sought to further uncover the molecular basis of bLf anticancer activity. We showed that bLf co-localizes with V-ATPase and cholesterol-rich lipid rafts at the plasma membrane of highly metastatic cancer cells. Our data also revealed that bLf perturbs cellular trafficking, induces intracellular accumulation of cholesterol and lipid rafts disruption, downregulates PI3K, and AKT or p-AKT and inhibits glycolysis of cancer cells harbouring V-ATPase at the plasma membrane lipid rafts. Altogether, our results can lay the foundation for future bLf-based targeted anticancer strategies as they unravel a novel cascade of molecular events that explains and further reinforces bLf selectivity for cancer cells displaying plasmalemmal V-ATPase.

Extracellular vesicles and particles impact the systemic landscape of cancer

Intercellular cross talk between cancer cells and stromal and immune cells is essential for tumor progression and metastasis. Extracellular vesicles and particles (EVPs) are a heterogeneous class of secreted messengers that carry bioactive molecules and that have been shown to be crucial for this cell-cell communication. Here, we highlight the multifaceted roles of EVPs in cancer. Functionally, transfer of EVP cargo between cells influences tumor cell growth and invasion, alters immune cell composition and function, and contributes to stromal cell activation. These EVP-mediated changes impact local tumor progression, foster cultivation of pre-metastatic niches at distant organ-specific sites, and mediate systemic effects of cancer. Furthermore, we discuss how exploiting the highly selective enrichment of molecules within EVPs has profound implications for advancing diagnostic and prognostic biomarker development and for improving therapy delivery in cancer patients. Altogether, these investigations into the role of EVPs in cancer have led to discoveries that hold great promise for improving cancer patient care and outcome.

Interplay between purinergic signalling and extracellular vesicles in health and disease

Purinergic signalling is a receptor-mediated process characterized by the binding of extracellular nucleotides and nucleosides to purinergic receptors, which results in the activation intracellular signalling pathways, and, ultimately, leads to changes in cell physiology. Purinergic signalling has been related to the regulation of important physiological processes (e.g., renal electrolyte reabsorption; platelet aggregation; immune response). In addition, it has been associated with pathophysiological situations such as cancer and inflammation. Extracellular vesicles (EVs) are nanoparticles released by all cells of the organism, which play a key role in cell-cell communication. In this regard, EVs can mediate effects on target cells located at distant locations. Within their cargo, EVs contain molecules with the potential to affect purinergic signalling at the target cells and tissues. Here, we review the studies addressing the regulation of purinergic signalling by EVs based on the cell type or tissue where the regulation takes place. In this regard, EVs are found to play a major role in modulating the extracellular ATP levels and, specially, adenosine. This has a clear impact on, for instance, the inflammatory and immune response against cancer cells. Furthermore, we discuss the data available on the regulation of EV secretion and its cargo by purinergic signalling. Here, a major role of the purinergic receptor P2X7 and again, an impact on processes such as inflammation, immune response and cancer pathogenesis has been established. Finally, we highlight uninvestigated aspects of these two regulatory networks and address their potential as therapeutic targets.

Dynamic Interactions between Tumor Cells and Brain Microvascular Endothelial Cells in Glioblastoma

Simple Summary

In glioblastoma (GBM), tumor cells develop a symbiotic relation with brain microvascular endothelial cells (BMECs) to shift tissue homeostasis toward a tumor-supporting context. Disentangling the molecular mechanisms that govern this dynamic interaction in the context of GBM represents an exciting challenge for the update of conventional treatment and for the development of novel therapeutic targets for this aggressive and lethal brain tumor.

Abstract

GBM is the most aggressive brain tumor among adults. It is characterized by extensive vascularization, and its further growth and recurrence depend on the formation of new blood vessels. In GBM, tumor angiogenesis is a multi-step process involving the proliferation, migration and differentiation of BMECs under the stimulation of specific signals derived from the cancer cells through a wide variety of communication routes. In this review, we discuss the dynamic interaction between BMECs and tumor cells by providing evidence of how tumor cells hijack the BMECs for the formation of new vessels. Tumor cell–BMECs interplay involves multiple routes of communication, including soluble factors, such as chemokines and cytokines, direct cell–cell contact and extracellular vesicles that participate in and fuel this cooperation. We also describe how this interaction is able to modify the BMECs structure, metabolism and physiology in a way that favors tumor growth and invasiveness. Finally, we briefly reviewed the recent advances and the potential future implications of some high-throughput 3D models to better understanding the complexity of BMECs–tumor cell interaction.

Energy Sources for Exosome Communication in a Cancer Microenvironment

Simple Summary

Exosomal communication in the tumor microenvironment plays a crucial role in cancer development, progression, and metastasis, and is achieved by either short-distance communication with neighboring cells or long-distance communication with distant organs. Nevertheless, how exosomes gain energy to establish such communication and the different sources of energy are unclear. Recently, a handful of studies have demonstrated the presence of mitochondria, adenosine triphosphate, and glycolytic enzymes, which may serve as potential energy sources for exosomes. This review clarifies how exosomes maintain their structural integrity and stability during their intracellular communication, and reviews evidence of their energy source.

Abstract

Exosomes are crucial extracellular vesicles (EVs) with a diameter of approximately 30–200 nm. They are released by most cell types in their extracellular milieu and carry various biomolecules, including proteins and nucleic acids. Exosomes are increasingly studied in various diseases, including cancer, due to their role in local and distant cell–cell communication in which they can promote tumor growth, cancer progression, and metastasis. Interestingly, a tremendous number of exosomes is released by malignant cancer cells, and these are then taken up by autologous and heterologous recipient stromal cells such as immune cells, cancer stem cells, and endothelial cells. All these events demand an enormous amount of energy and require that exosomes remain stable while having the capacity to reach distant sites and cross physical barriers. Nevertheless, there is a dearth of research pertaining to the energy sources of exosomes, and questions remain about how they maintain their motility in the tumor microenvironment (TME) and beyond. Moreover, exosomes can produce adenosine triphosphate (ATP), an important energy molecule required by all cells, and mitochondria have been identified as one of the exosomal cargoes. These findings strengthen the prospect of exosomal communication via transfer of mitochondria and the bioenergetics of target recipient cells. In the TME, the accumulation of ATP and lactate may facilitate the entry of exosomes into cancer cells to promote metastasis, as well as help to target cancer cells at the tumor site. This review highlights how exosomes obtain sufficient energy to thrive in the TME and communicate with distant physiological destinations.

Amniotic fluid stem cell-derived extracellular vesicles are independent metabolic units capable of modulating inflammasome activation in THP-1 cells

An immunoregulatory role of stem cells, often mediated by their secretome, has been claimed by several studies. Stem cell-derived extracellular vesicles (EVs) are crucial components of the secretome. EVs, a heterogeneous group of membranous vesicles released by many cell types into the extracellular space, are now considered as an additional mechanism for intercellular communication. In this study, we aimed at investigating whether human amniotic stem cell-derived extracellular vesicles (HASC-EVs) were able to interfere with inflammasome activation in the THP-1 cell line. Two subsets of HASC-EVs were collected by sequential centrifugation, namely HASC-P10 and HASC-P100. We demonstrated that HASC-EVs were neither internalized into nor undertake a direct interaction with THP-1 cells. We showed that HASC-P10 and P100 were able to intrinsically produce ATP, which was further converted to adenosine by 5'-nucleotidase (CD73) and ectonucleoside triphosphate diphosphohydrolase-1 (CD39). We found that THP-1 cells conditioned with both types of HASC-EVs failed to activate the NLRP3/caspase-1/inflammasome platform in response to LPS and ATP treatment by a mechanism involving A2a adenosine receptor activation. These results support a role for HASC-EVs as independent metabolic units capable of modifying the cellular functions, leading to anti-inflammatory effects in monocytic cells.

The role of the metabolite cargo of extracellular vesicles in tumor progression

Metabolomic reprogramming in tumor and stroma cells is a hallmark of cancer but understanding its effects on the metabolite composition and function of tumor-derived extracellular vesicles (EVs) is still in its infancy. EVs are membrane-bound sacs with a complex molecular composition secreted by all living cells. They are key mediators of intercellular communication both in normal and pathological conditions and play a crucial role in tumor development. Although lipids are major components of EVs, most of the EV cargo studies have targeted proteins and nucleic acids. The potential of the EV metabolome as a source for biomarker discovery has gained recognition recently, but knowledge on the biological activity of tumor EV metabolites still remains limited. Therefore, we aimed (i) to compile the list of metabolites identified in tumor EVs isolated from either clinical specimens or in vitro samples and (ii) describe their role in tumor progression through literature search and pathway analysis.

A validated analysis pipeline for mass spectrometry-based vitreous proteomics: new insights into proliferative diabetic retinopathy

Background

Vitreous is an accessible, information-rich biofluid that has recently been studied as a source of retinal disease-related proteins and pathways. However, the number of samples required to confidently identify perturbed pathways remains unknown. In order to confidently identify these pathways, power analysis must be performed to determine the number of samples required, and sample preparation and analysis must be rigorously defined.

Methods

Control (n = 27) and proliferative diabetic retinopathy (n = 23) vitreous samples were treated as biologically distinct individuals or pooled together and aliquoted into technical replicates. Quantitative mass spectrometry with tandem mass tag labeling was used to identify proteins in individual or pooled control samples to determine technical and biological variability. To determine effect size and perform power analysis, control and proliferative diabetic retinopathy samples were analyzed across four 10-plexes. Pooled samples were used to normalize the data across plexes and generate a single data matrix for downstream analysis.

Results

The total number of unique proteins identified was 1152 in experiment 1, 989 of which were measured in all samples. In experiment 2, 1191 proteins were identified, 727 of which were measured across all samples in all plexes. Data are available via ProteomeXchange with identifier PXD025986. Spearman correlations of protein abundance estimations revealed minimal technical (0.99–1.00) and biological (0.94–0.98) variability. Each plex contained two unique pooled samples: one for normalizing across each 10-plex, and one to internally validate the normalization algorithm. Spearman correlation of the validation pool following normalization was 0.86–0.90. Principal component analysis revealed stratification of samples by disease and not by plex. Subsequent differential expression and pathway analyses demonstrated significant activation of metabolic pathways and inhibition of neuroprotective pathways in proliferative diabetic retinopathy samples relative to controls.

Conclusions

This study demonstrates a feasible, rigorous, and scalable method that can be applied to future proteomic studies of vitreous and identifies previously unrecognized metabolic pathways that advance understanding of diabetic retinopathy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12014-021-09328-8.

Multiple Myeloma Cell-Derived Exosomes: Implications on Tumorigenesis, Diagnosis, Prognosis and Therapeutic Strategies

Multiple myeloma (MM) is a hematological disease that is still not curable. The bone marrow milieu, with cellular and non-cellular elements, participate in the creation of a pro-tumoral environment enhancing growth and survival of MM plasma cells. Exosomes are vesicles oscillating in dimension between 50 nm and 100 nm in size that can be released by various cells and contribute to the pathogenesis and progression of MM. Exosomes enclose proteins, cytokines, lipids, microRNAs, long noncoding RNAs, and circular RNAs able to regulate interactions between MM plasma cells and adjacent cells. Through exosomes, mesenchymal stem cells confer chemoresistance to MM cells, while myeloma cells promote angiogenesis, influence immune response, cause bone lesions, and have an impact on the outcome of MM patients. In this review, we analyze the role played by exosomes in the progression of monoclonal gammopathies and the effects on the proliferation of neoplastic plasma cells, and discuss the possible employment of exosomes as potential targets for the treatment of MM patients.

DAL-1/4.1B promotes the uptake of exosomes in lung cancer cells via Heparan Sulfate Proteoglycan 2 (HSPG2)

DAL-1/4.1B is frequently absent in lung cancer tissues, which is significantly related to the occurrence and development of lung cancer. In this research, we found that DAL-1/4.1B affected the uptake of exosomes by lung cancer cells. When the expression of DAL-1/4.1B increased and decreased, the ability of exosome uptake enhanced and attenuated correspondingly. And we found that when cells were treated with different vesicles uptake inhibitors (chlorpromazine, methyl-β-cyclodextrin (MβCD), cytochalasin D, chloroquine and heparin) and heparinase (HSPE), only heparin and HSPE counteracted the uptake enhancement effect caused by DAL-1/4.1B. Therefore, we speculated that DAL-1/4.1B might promote the uptake of exosomes through the heparan sulfate proteoglycans (HSPGs) pathway. After screening the expression of HSPGs and HSPE in H292 cells, the expression of heparan sulfate proteoglycan 2 (HSPG2) increased with overexpression of DAL-1/4.1B and decreased with knockdown of DAL-1/4.1B. Meanwhile, exosome uptake decreased with HSPG2 knockdown in H292 and DAL-1/4.1B-overexpressing H292 cells. Moreover, knockdown of DAL-1/4.1B and HSPG2 in lung cancer A549 cells resulted in a similar decrease in exosome uptake, and the expression of HSPG2 was also decreased with DAL-1/4.1B knockdown. These results indicated that HSPG2 directly affected the uptake of exosomes, while DAL-1/4.1B positively affected the expression of HSPG2. Therefore, DAL-1/4.1B may promote cellular adhesion and inhibit migration in cancer cells.

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.

Extracellular Vesicles in Cancer Metabolism: Implications for Cancer Diagnosis and Treatment

Metabolic reprogramming is one of the most common characteristics of cancer cells. The metabolic alterations of glucose, amino acids and lipids can support the aggressive phenotype of cancer cells. Exosomes, a kind of extracellular vesicles, participate in the intercellular communication through transferring bioactive molecules. Increasing evidence has demonstrated that enzymes, metabolites and non-coding RNAs in exosomes are responsible for the metabolic alteration of cancer cells. In this review, we summarize the past and recent findings of exosomes in altering cancer metabolism and elaborate on the role of the specific enzymes, metabolites and non-coding RNAs transferred by exosomes. Moreover, we give evidence of the role of exosomes in cancer diagnosis and treatment. Finally, we discuss the existing problems in the study and application of exosomes in cancer diagnosis and treatment.

PROKR1 delivery by cell-derived vesicles restores the myogenic potential of Prokr1-deficient C2C12 myoblasts

Cell-derived vesicles (CDVs) have been investigated as an alternative to exosomes. Here, we generated CDVs from Prokineticin receptor 1 (PROKR1) overexpressing HEK293T cells using micro-extrusion. More than 60 billion PROKR1-enriched CDV (PROKR1^Tg CDVs) particles with canonical exosome properties were recovered from 10⁷ cells. With 25 μg/mL of PROKR1^Tg CDVs, we observed delivery of PROKR1, significant reduction of apoptosis, and myotube formation in C2C12^Prokr1-/- myoblasts that have lost their myogenic potential but underwent apoptosis following myogenic commitment. Expression levels of early and late myogenic marker genes and glucose uptake capacity were restored to equivalent levels with wild-type control. Furthermore, PROKR1^Tg CDVs were accumulated in soleus muscle comparable to the liver without significant differences. Therefore, CDVs obtained from genetically engineered cells appear to be an effective method of PROKR1 protein delivery and offer promise as an alternative therapy for muscular dystrophy.

Seminal exosomes - An important biological marker for various disorders and syndrome in human reproduction

BACKGROUND

Exosomes are nano-sized membrane vesicles, secreted by different types of cells into the body's biological fluids. They are found in abundance in semen as compared to other fluids. Exosomes contain a cargo of lipid molecules, proteins, phospholipids, cholesterol, mRNAs, and miRNAs. Each molecule of seminal exosomes (SE) has a potential role in male reproduction for childbirth. Many potential candidates are available within the seminal exosomes that can be used as diagnostic markers for various diseases or syndromes associated with male reproduction. Also these seminal exospmes play a major role in female reproductive tract for effective fertilization.

AIM

The aim of this review is to focus on the advancement of human seminal exosomal research and its various properties.

METHODS

We used many databases like Scopus, Google scholar, NCBI-NLM and other sources to filter the articles of interest published in exosomes. We used phrases like "Exosomes in human semen", "Composition of exosomes in human semen" and other relevant words to filter the best articles.

RESULTS

Seminal exosomes play a major role in sperm functions like cell-to-cell communication, motility of the sperm cells, maintaining survival capacity for the sperm in the female reproductive tract and spermatogenesis. Also, seminal exosomes are used as a carrier for many regulatory elements using small RNA molecules. miRNAs of the seminal exosomes can be used as a diagnostic marker for prostate cancer instead of prostate specific antigen (PSA). Epididymosomes can be used as a biomarker for reproductive diseases and male infertility.

CONCLUSION

Seminal exosomes could be used as biological markers for various reproductive disorders, male infertility diagnosis, and it can be used in anti-retroviral research for the identification of novel therapeutics for HIV-1 infection and transmission.

Long non-coding RNA NORAD promotes the prostate cancer cell extracellular vesicle release via microRNA-541-3p-regulated PKM2 to induce bone metastasis of prostate cancer

BACKGROUND

Bone metastasis is the leading cause of mortality and reduced quality of life in patients with metastatic prostate cancer (PCa). Long non-coding RNA activated by DNA damage (NORAD) has been observed to have an abnormal expression in various cancers. This article aimed to explore the molecular mechanism underlying the regulatory role of NORAD in bone metastasis of PCa.

METHODS

NORAD expression in clinical PCa tissues and cell lines was detected with the application of qRT-PCR. Cancer cells were then transfected with plasmids expressing NORAD, after which Transwell assay and CCK-8 assay were carried out to detect proliferation, migration, and bone metastasis of PCa. NORAD downstream target molecules were screened through bioinformatics analysis, followed by further verification using dual luciferase assay. Extracellular vesicles (EVs) were labeled with PKH67 and interacted with bone marrow stromal cells. The gain- and loss-function method was applied to determine the internalization and secretion of PCa cells-derived EVs under the intervention of downstream target molecules or NORAD.

RESULTS

PCa tissues and cell lines were observed to have a high expression of NORAD, particularly in tissues with bone metastasis. NORAD knockdown resulted in reduced secretion and internalization of EVs, and suppressed proliferation, migration, and bone metastasis of PCa cells. It was indicated that NORAD interacted with miR-541-3p, leading to the upregulation of PKM2. Forced expression of PKM2 promoted the transfer of PKH67-labeled EVs to bone marrow stromal cells.

CONCLUSIONS

NORAD might serve as a ceRNA of miR-541-3p to promote PKM2 expression, thereby enhancing the development of bone metastasis in PCa by promoting internalization and transfer of EVs of cancer cells, providing an insight into a novel treatment for the disorder.

Molecular cargo in myeloid-derived suppressor cells and their exosomes

Collaborative research is reviewed in which mass spectrometry-based proteomics and next generation sequencing were used qualitatively and quantitatively to interrogate proteins and RNAs carried in intact myeloid-derived suppressor cells (MDSC) and exosomes shed in vitro by MDSC. In aggregate exosomes more than 4000 proteins were identified, including annexins and immunosuppressive mediators. Bioassays showed that exosomes induce MDSC chemotaxis dependent on S100A8 and S100A9 in their cargo. Surface selective chemistry identified glycoproteins on MDSC and exosome surfaces, including CD47 and thrombospondin 1, which both facilitate exosome-catalyzed chemotaxis. Large numbers of mRNAs and microRNAs were identified in aggregate exosomes, whose potential functions in receptor cells include angiogenesis, and proinflammatory and immunosuppressive activities. Inflammation was found to have asymmetric effects on MDSC and exosomal cargos. Collectively, our findings indicate that the exosomes shed by MDSC provide divergent and complementary functions that support the immunosuppression and tumor promotion activities of MDSC.

Cooperation and Interplay between EGFR Signalling and Extracellular Vesicle Biogenesis in Cancer

Epidermal growth factor receptor (EGFR) takes centre stage in carcinogenesis throughout its entire cellular trafficking odyssey. When loaded in extracellular vesicles (EVs), EGFR is one of the key proteins involved in the transfer of information between parental cancer and bystander cells in the tumour microenvironment. To hijack EVs, EGFR needs to play multiple signalling roles in the life cycle of EVs. The receptor is involved in the biogenesis of specific EV subpopulations, it signals as an active cargo, and it can influence the uptake of EVs by recipient cells. EGFR regulates its own inclusion in EVs through feedback loops during disease progression and in response to challenges such as hypoxia, epithelial-to-mesenchymal transition and drugs. Here, we highlight how the spatiotemporal rules that regulate EGFR intracellular function intersect with and influence different EV biogenesis pathways and discuss key regulatory features and interactions of this interplay. We also elaborate on outstanding questions relating to EGFR-driven EV biogenesis and available methods to explore them. This mechanistic understanding will be key to unravelling the functional consequences of direct anti-EGFR targeted and indirect EGFR-impacting cancer therapies on the secretion of pro-tumoural EVs and on their effects on drug resistance and microenvironment subversion.

Extracellular Vesicles in Glioblastoma Tumor Microenvironment

Glioblastomas (GBM) are highly aggressive primary brain tumors. Complex and dynamic tumor microenvironment (TME) plays a crucial role in the sustained growth, proliferation, and invasion of GBM. Several means of intercellular communication have been documented between glioma cells and the TME, including growth factors, cytokines, chemokines as well as extracellular vesicles (EVs). EVs carry functional genomic and proteomic cargo from their parental cells and deliver that information to surrounding and distant recipient cells to modulate their behavior. EVs are emerging as crucial mediators of establishment and maintenance of the tumor by modulating the TME into a tumor promoting system. Herein we review recent literature in the context of GBM TME and the means by which EVs modulate tumor proliferation, reprogram metabolic activity, induce angiogenesis, escape immune surveillance, acquire drug resistance and undergo invasion. Understanding the multifaceted roles of EVs in the niche of GBM TME will provide invaluable insights into understanding the biology of GBM and provide functional insights into the dynamic EV-mediated intercellular communication during gliomagenesis, creating new opportunities for GBM diagnostics and therapeutics.

Characterization of protein, long noncoding RNA and microRNA signatures in extracellular vesicles derived from resting and degranulated mast cells

Mast cells (MCs) are known to participate in a variety of patho-physiological processes depending largely on the intragranular mediators and the production of cytokines and chemokines during degranulation. Recently, extracellular vesicles (EVs) have been implicated important functions for MCs, but the components of MC-derived EVs have not yet been well-characterized. In this study, we aimed to identify signatures of proteins, long non-coding RNAs (lncRNAs), and microRNAs (miRNAs) in EVs derived from resting (Rest-EV) and degranulated (Sti-EV) MCs by differential ultracentrifugation. Using tandem mass tag (TMT)-based quantitative proteomics technology and RNA sequencing, we identified a total of 1988 proteins, 397 lncRNAs, and 272 miRNAs in Rest-EV and Sti-EV. The proteins include common EVs markers (cytoskeletal proteins), MCs markers (FcεRI and tryptase), and some preformed MCs mediators (lysosomal enzymes) as well. The global expression profiles of lncRNAs and miRNAs identified, for the first time, from Rest-EV and Sti-EV, strongly suggest a potential regulatory function of MC-derived EVs. We have also performed Western blotting and qRT-PCR analysis to further verify some of the proteins, lncRNAs, and miRNAs identified from Rest-EV and Sti-EV. Our findings will help to elucidate the functions of MC-derived EVs, and provide a reference dataset for future translational studies involving MC-derived EVs.

Top-Down Proteomic Characterization of Truncated Proteoforms

A top-down proteomic strategy with semiautomated analysis of data sets has proven successful for the global identification of truncated proteins without the use of chemical derivatization, enzymatic manipulation, immunoprecipitation, or other enrichment. This approach provides the reliable identification of internal polypeptides formed from precursor gene products by proteolytic cleavage of both the N- and C-termini, as well as truncated proteoforms that retain one or the other termini. The strategy has been evaluated by application to the immunosuppressive extracellular vesicles released by myeloid-derived suppressor cells. More than 1000 truncated proteoforms have been identified, from which binding motifs are derived to allow characterization of the putative proteases responsible for truncation.

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.

Extracellular vesicles and energy metabolism

Glycolytic enzymes are among the most frequently identified proteins in proteomics of exosomes/extracellular vesicles. This review brings up the possibility that exosomes/extracellular vesicles during their life-time in bodily fluids power important energy-consuming functions by glycolytic conversion of glucose or fructose into ATP. It was seen that prostasomes (exosomes of the prostate) could produce ATP by glycolysis and that the produced ATP quickly was consumed by adjacent prostasomal ATPases. The glycolytic ATP production appeared to be coupled to self-sustaining energy requirements. It will also be discussed how a failure in this machinery (lowered activity of ATPases) with a resultant polluting leakage of extracellular ATP could affect cancer development.

Exosomes and cardiovascular cell–cell communication

Exosomes have become an important player in intercellular signaling. These lipid microvesicles can stably transfer miRNA, protein, and other molecules between cells and circulate throughout the body. Exosomes are released by almost all cell types and are present in most if not all biological fluids. The biologically active cargo carried by exosomes can alter the phenotype of recipient cells. Exosomes increasingly are recognized as having an important role in the progression and treatment of cardiac disease states. Injured cardiac cells can release exosomes with important pathological effects on surrounding tissue, in addition to effecting other organs. But of equal interest is the possible benefit(s) conferred by exosomes released from stem cells for use in treatment and possible repair of cardiac damage.

A new role for extracellular vesicles: how small vesicles can feed tumors' big appetite

Cancer cells must adapt their metabolism in order to meet the energy requirements for cell proliferation, survival in nutrient-deprived environments, and dissemination. In particular, FA metabolism is emerging as a critical process for tumors. FA metabolism can be modulated through intrinsic changes in gene expression or signaling between tumor cells and also in response to signals from the surrounding microenvironment. Among these signals, extracellular vesicles (EVs) could play an important role in FA metabolism remodeling. In this review, we will present the role of EVs in tumor progression and especially in metabolic reprogramming. Particular attention will be granted to adipocytes. These cells, which are specialized in storing and releasing FAs, are able to shift tumor metabolism toward the use of FAs and, subsequently, increase tumor aggressiveness. Recent work demonstrates the involvement of EVs in this metabolic symbiosis.

Ubiquitin Conjugation Probed by Inflammation in Myeloid-Derived Suppressor Cell Extracellular Vesicles

Ubiquitinated proteins carried by the extracellular vesicles (EV) released by myeloid-derived suppressor cells (MDSC) have been investigated using proteomic strategies to examine the effect of tumor-associated inflammation. EV were collected from MDSC directly following isolation from tumor-bearing mice with low and high inflammation. Among the 1092 proteins (high inflammation) and 925 proteins (low inflammation) identified, more than 50% were observed as ubiquitinated proteoforms. More than three ubiquitin-attachment sites were characterized per ubiquitinated protein, on average. Multiple ubiquitination sites were identified in the pro-inflammatory proteins S100 A8 and S100 A9, characteristic of MDSC and in histones and transcription regulators among other proteins. Spectral counting and pathway analysis suggest that ubiquitination occurs independently of inflammation. Some ubiquitinated proteins were shown to cause the migration of MDSC, which has been previously connected with immune suppression and tumor progression. Finally, MDSC EV are found collectively to carry all the enzymes required to catalyze ubiquitination, and the hypothesis is presented that a portion of the ubiquitinated proteins are produced in situ.

Protein and Molecular Characterization of a Clinically Compliant Amniotic Fluid Stem Cell-Derived Extracellular Vesicle Fraction Capable of Accelerating Muscle Regeneration Through Enhancement of Angiogenesis

The secretome of human amniotic fluid stem cells (AFSCs) has great potential as a therapeutic agent in regenerative medicine. However, it must be produced in a clinically compliant manner before it can be used in humans. In this study, we developed a means of producing a biologically active secretome from AFSCs that is free of all exogenous molecules. We demonstrate that the full secretome is capable of promoting stem cell proliferation, migration, and protection of cells against senescence. Furthermore, it has significant anti-inflammatory properties. Most importantly, we show that it promotes tissue regeneration in a model of muscle damage. We then demonstrate that the secretome contains extracellular vesicles (EVs) that harbor much, but not all, of the biological activity of the whole secretome. Proteomic characterization of the EV and free secretome fraction shows the presence of numerous molecules specific to each fraction that could be key regulators of tissue regeneration. Intriguingly, we show that the EVs only contain miRNA and not mRNA. This suggests that tissue regeneration in the host is mediated by the action of EVs modifying existing, rather than imposing new, signaling pathways. The EVs harbor significant anti-inflammatory activity as well as promote angiogenesis, the latter may be the mechanistic explanation for their ability to promote muscle regeneration after cardiotoxin injury.

Metastatic state of parent cells influences the uptake and functionality of prostate cancer cell-derived extracellular vesicles

Extracellular vesicles (EVs), including microvesicles and exosomes, mediate intercellular signalling which has a profound role in cancer progression and in the development of metastasis. Internalisation of EVs can prompt functional changes in the recipient cells, the nature of which depends on the molecular composition and the cargo of the EVs. We hypothesised that the metastatic stage of cancerous parent cells would determine the uptake efficacy and the subsequent functional effects of the respective cancer cell-derived EVs. To address this question, we compared the internalisation of EVs derived from two metastatic site-derived prostate cancer cell lines (PC-3 and LNCaP), human telomerase reverse transcriptase immortalised primary malignant prostate epithelial cells (RC92a/hTERT), and a benign epithelial prostate cell line (PNT2). EVs isolated from the metastatic site-derived PC-3 and LNCaP cells were more efficiently internalised by the PC-3 and PNT2 cells compared to the EVs from the primary malignant RC92a/hTERT cells or the benign PNT2 cells, as determined by high content microscopy, confocal microscopy, and flow cytometry. EV uptake was also influenced by the phase of the cell cycle, so that an increased EV-derived fluorescence signal was observed in the cells at the G₂/M phase compared to the G₀/G₁ or S phases. Finally, differences were also observed in the functions of the recipient cells based on the EV source. Proliferation of PNT2 cells and to a lesser extent also PC-3 cells was enhanced particularly by the EVs from the metastatic-site-derived prostate cancer cells in comparison to the EVs from the benign cells or primary cancer cells, whereas migration of PC-3 cells was enhanced by all cancerous EVs. RESPONSIBLE EDITOR Takahiro Ochiya, National Cancer Center, Japan.

Exosomes as agents of change in the cardiovascular system

Exosomes have an evolving role in paracrine and autocrine signaling, which is enhanced because these lipid vesicles are quite stable and can deliver miRNA, DNA, protein and other molecules to cells throughout the body. Most cell types release exosomes, and exosomes are found in all biological fluids, making them accessible biomarkers. Significantly, exosomes can carry a biologically potent cargo, which can alter the phenotype of recipient cells. In the cardiovascular system exosomes have been primarily studied for their role in mediating the beneficial effects of mesenchymal stem cells after myocardial injury. Exosomes released by cardiac cells in disease states, such as myocardial ischemia, can potentially have important pathophysiologic effects on other cardiac cells as well as on distant organs.

Exosomes: promising sacks for treating ischemic heart disease?

Ischemic heart disease(IHD) is the leading cause of death worldwide. Despite the development of continuously improving therapeutic strategies, morbidity and mortality of patients with IHD remain relatively high. Exosomes are a subpopulation of vesicles that are universally recognized as major mediators in intercellular communication. Numerous preclinical studies have shown that these tiny vesicles were protective in IHD, through such actions as alleviating myocardial ischemia-reperfusion injury, promoting angiogenesis, inhibiting fibrosis, and facilitating cardiac regeneration. Our review focused on these beneficial exosome-mediated processes. In addition, we discuss in detail how to fully exploit the therapeutic potentials of exosomes in the field of IHD. Topics include identifying robust sources of exosomes, loading protective agents into exosomes, developing heart-specific exosomes, optimizing isolation methods, and translating the cardioprotective effects of exosomes into clinical practice. Finally, both the advantages and disadvantages of utilizing exosomes in clinical settings are addressed.

Extracellular vesicles for liquid biopsy in prostate cancer: where are we and where are we headed?

Background:

Extracellular vesicles (EVs) are a heterogeneous class of lipid bound particles shed by any cell in the body in physiological and pathological conditions. EVs play critical functions in intercellular communication. EVs can actively travel in intercellular matrices and eventually reach the circulation. They can also be released directly in biological fluids where they appear to be stable. Because the molecular content of EVs reflects the composition of the cell of origin, they have recently emerged as a promising source of biomarkers in a number of diseases. EV analysis is particularly attractive in cancer patients that frequently present with increased numbers of circulating EVs.

Methods:

We sought to review the current literature on the molecular profile of prostate cancer-derived EVs in model systems and patient biological fluids in an attempt to draw some practical and universal conclusions on the use of EVs as a tool for liquid biopsy in clinical specimens.

Results:

We discuss advantages and limitations of EV-based liquid biopsy approaches summarizing salient studies on protein, DNA and RNA. Several candidate biomarkers have been identified so far but these results are difficult to apply to the clinic. However, the field is rapidly moving toward the implementation of novel tools to isolate cancer-specific EVs that are free of benign EVs and extra-vesicular contaminants. This can be achieved by identifying markers that are exquisitely present in tumor cell-derived EVs. An important contribution might also derive from a better understanding of EV types that may play specific functions in tumor progression and that may be a source of cancer-specific markers.

Conclusions:

EV analysis holds strong promises for the development of non-invasive biomarkers in patients with prostate cancer. Implementation of modern methods for EV isolation and characterization will enable to interrogate circulating EVs in vivo.

Exosomes and Exosomal MicroRNAs in Prostate Cancer Radiation Therapy

Despite current risk stratification systems using traditional clinicopathologic factors, many localized and locally advanced prostate cancers fail radical treatment (ie, radical prostatectomy, radiation therapy with or without androgen deprivation therapy). Therefore, a pressing need exists for enhanced methods of disease stratification through novel prognostic and predictive tools that can reliably be applied in clinical practice. Exosomes are 50- to 150-nm small vesicles released by cancer cells that reflect the genetic and nongenetic materials of parent cancer cells. Cancer cells can contain distinct sets of microRNA profiles, the expression of which can change owing to stress such as radiation therapy. These alterations or distinctions in contents allow exosomes to be used as prognostic and/or predictive biomarkers and to monitor the treatment response. Additionally, microRNAs have been shown to influence multiple processes in prostate tumorigenesis, including cell proliferation, induction of apoptosis, migration, oncogene inhibition, and radioresistance. Thus, comparative exosomal microRNA profiling at different levels could help portray tumor aggressiveness and response to radiation therapy. Although technical challenges persist in exosome isolation and characterization, recent improvements in microRNA profiling have evolved toward in-depth analyses of the exosomal cargo and its functions. We have reviewed the role of exosomes and exosomal microRNAs in biologic processes of prostate cancer progression and radiation therapy response, with a particular focus on the development of clinical assays for treatment personalization.

Obstacles and opportunities in the functional analysis of extracellular vesicle RNA - an ISEV position paper

The release of RNA-containing extracellular vesicles (EV) into the extracellular milieu has been demonstrated in a multitude of different in vitro cell systems and in a variety of body fluids. RNA-containing EV are in the limelight for their capacity to communicate genetically encoded messages to other cells, their suitability as candidate biomarkers for diseases, and their use as therapeutic agents. Although EV-RNA has attracted enormous interest from basic researchers, clinicians, and industry, we currently have limited knowledge on which mechanisms drive and regulate RNA incorporation into EV and on how RNA-encoded messages affect signalling processes in EV-targeted cells. Moreover, EV-RNA research faces various technical challenges, such as standardisation of EV isolation methods, optimisation of methodologies to isolate and characterise minute quantities of RNA found in EV, and development of approaches to demonstrate functional transfer of EV-RNA in vivo. These topics were discussed at the 2015 EV-RNA workshop of the International Society for Extracellular Vesicles. This position paper was written by the participants of the workshop not only to give an overview of the current state of knowledge in the field, but also to clarify that our incomplete knowledge – of the nature of EV(-RNA)s and of how to effectively and reliably study them – currently prohibits the implementation of gold standards in EV-RNA research. In addition, this paper creates awareness of possibilities and limitations of currently used strategies to investigate EV-RNA and calls for caution in interpretation of the obtained data.

Extracellular vesicles swarm the cancer microenvironment: from tumor-stroma communication to drug intervention

Intercellular communication sets the pace for transformed cells to survive and to thrive. Extracellular vesicles (EVs), such as exosomes, microvesicles and large oncosomes, are involved in this process shuttling reciprocal signals and other molecules between transformed and stromal cells, including fibroblasts, endothelial and immune cells. As a result, these cells are adapted or recruited to a constantly evolving cancer microenvironment. Moreover, EVs take part in the response to anticancer therapeutics not least by promoting drug resistance throughout the targeted tumor. Finally, circulating EVs can also transport important molecules to remote destinations in order to prime metastatic niches in an otherwise healthy tissue. Although the understanding of EV biology remains a major challenge in the field, their characteristics create new opportunities for advances in cancer diagnostics and therapeutics.

Caspase-3-dependent cleavage of Bcl-xL in the stroma exosomes is required for their uptake by hematological malignant cells

The intercellular crosstalk between hematological malignancies and the tumor microenvironment is mediated by cell-to-cell interactions and soluble factors. One component of the secretome that is gaining increasing attention is the extracellular vesicles and, in particular, the exosomes. Apart from the role as vectors of molecular information, exosomes have been shown to possess intrinsic biological activity. In this study, we found that caspase-3 is activated in L88 bone marrow stroma cell-derived exosomes and identified 1 of the substrates to be the antiapoptotic protein Bcl-xL. The cleaved Bcl-xL is found in a panel of normal and cancer cell-derived exosomes and is localized on the outer leaflet of the exosomal membrane. Incubation of the exosomes with a caspase-3 inhibitor or the pan-caspase inhibitor prevents the cleavage of Bcl-xL. Importantly, MCF-7 cell-derived exosomes that are caspase-3-deficient are enriched in full-length Bcl-xL, whereas ectopic expression of caspase-3 restores the cleavage of Bcl-xL. Chemical inhibition of Bcl-xL with ABT737 or molecular inhibition by using the D61A and D76A Bcl-xL mutant leads to a significant decrease in the uptake of exosomes by hematopoietic malignant cells. These data indicate that the cleaved Bcl-xL is required for the uptake of exosomes by myeloma and lymphoma cells, leading to their increased proliferation. In summary, we demonstrate for the first time that Bcl-xL is an exosomal caspase-3 substrate and that this processing is required for the uptake of exosomes by recipient cells.