Barriers to horizontal cell transformation by extracellular vesicles containing oncogenic H-ras

Extracellular vesicles promote activation of pro-inflammatory cancer-associated fibroblasts in oral cancer

Introduction: Oral squamous cell carcinoma (OSCC) is the most common form of head and neck cancer and has a survival rate of ∼50% over 5 years. New treatment strategies are sorely needed to improve survival rates-and a better understanding of the mechanisms underlying tumorigenesis is needed to develop these strategies. The role of the tumor microenvironment (TME) has increasingly been identified as crucial in tumor progression and metastasis. One of the main constituents of the TME, cancer-associated fibroblasts (CAFs), plays a key role in influencing the biological behavior of tumors. Multiple mechanisms contribute to CAF activation, such as TGFβ signaling, but the role of extracellular vesicles (EVs) in CAF activation in OSCC is poorly understood. Assessing the impact of oral cancer-derived EVs on CAF activation will help to better illuminate OSCC pathophysiology and may drive development of novel treatments options. Methods: EVs were isolated from OSCC cell lines (Cal 27, SCC-9, SCC-25) using differential centrifugation. Nanoparticle tracking analysis was used for EV characterization, and Western blot to confirm the presence of EV protein markers. Oral fibroblasts were co-cultured with enriched EVs, TGFβ, or PBS over 72 h to assess activation. Flow cytometry was used to evaluate CAF markers. RNA collected from fibroblasts was extracted and the transcriptome was sequenced. Conditioned media from the co-cultures was evaluated with cytokine array profiling. Results: OSCC-derived EVs can activate oral fibroblasts into CAFs that are different from those activated by TGFβ, suggesting different mechanisms of activation and different functional properties. Gene set enrichment analysis showed several upregulated inflammatory pathways in those CAFs exposed to OSCC-derived EVs. Marker genes for inflammatory CAF subtypes were also upregulated, but not in CAFs activated by TGFβ. Finally, cytokine array analysis on secreted proteins revealed elevated levels of several pro-inflammatory cytokines from EV-activated CAFs, for instance IL-8 and CXCL5. Discussion: Our results reveal the ability of OSCC-derived EVs to activate fibroblasts into CAFs. These CAFs seem to have unique properties, differing from TGFβ-activated CAFs. Gaining an understanding of the interplay between EVs and stromal cells such as CAFs could lead to further insights into OSCC tumorigenesis and potential novel therapeutics.

Horizontal Transfer of Malignant Traits and the Involvement of Extracellular Vesicles in Metastasis

Metastases are responsible for the vast majority of cancer deaths, yet most therapeutic efforts have focused on targeting and interrupting tumor growth rather than impairing the metastatic process. Traditionally, cancer metastasis is attributed to the dissemination of neoplastic cells from the primary tumor to distant organs through blood and lymphatic circulation. A thorough understanding of the metastatic process is essential to develop new therapeutic strategies that improve cancer survival. Since Paget's original description of the "Seed and Soil" hypothesis over a hundred years ago, alternative theories and new players have been proposed. In particular, the role of extracellular vesicles (EVs) released by cancer cells and their uptake by neighboring cells or at distinct anatomical sites has been explored. Here, we will outline and discuss these alternative theories and emphasize the horizontal transfer of EV-associated biomolecules as a possibly major event leading to cell transformation and the induction of metastases. We will also highlight the recently discovered intracellular pathway used by EVs to deliver their cargoes into the nucleus of recipient cells, which is a potential target for novel anti-metastatic strategies.

Cancer as an infective disease: the role of EVs in tumorigenesis

Cancer is conventionally considered an evolutionary disease where tumor cells adapt to the environment and evolve eventually leading to the formation of metastasis through the seeding and growth of metastasis-initiating cells in distant organs. Tumor cell and tumor-stroma communication via soluble factors and extracellular vesicles (EVs) are essential for the success of the metastatic process. As the field of EVs advances, growing data support the role of tumor-derived EVs not only in modifying the microenvironment to facilitate tumor progression but also in inducing changes in cells outside the primary tumor that may lead to a malignant transformation. Thus, an alternative hypothesis has emerged suggesting the conceptualization of cancer as an 'infective' disease. Still, tackling EVs as a possible cancer treatment has not been widely explored. A major understanding is needed to unveil possible additional contributions of EVs in progression and metastasis, which may be essential for the development of novel approaches to treat cancer patients. Here, we review the contribution of EVs to cancer progression and the possible implication of these factors in the oncogenic transformation of indolent cells.

CAR-T-Derived Extracellular Vesicles: A Promising Development of CAR-T Anti-Tumor Therapy

Extracellular vesicles (EVs) are a heterogenous population of plasma membrane-surrounded particles that are released in the extracellular milieu by almost all types of living cells. EVs are key players in intercellular crosstalk, both locally and systemically, given that they deliver their cargoes (consisting of proteins, lipids, mRNAs, miRNAs, and DNA fragments) to target cells, crossing biological barriers. Those mechanisms further trigger a wide range of biological responses. Interestingly, EV phenotypes and cargoes and, therefore, their functions, stem from their specific parental cells. For these reasons, EVs have been proposed as promising candidates for EV-based, cell-free therapies. One of the new frontiers of cell-based immunotherapy for the fight against refractory neoplastic diseases is represented by genetically engineered chimeric antigen receptor T (CAR-T) lymphocytes, which in recent years have demonstrated their effectiveness by reaching commercialization and clinical application for some neoplastic diseases. CAR-T-derived EVs represent a recent promising development of CAR-T immunotherapy approaches. This crosscutting innovative strategy is designed to exploit the advantages of genetically engineered cell-based immunotherapy together with those of cell-free EVs, which in principle might be safer and more efficient in crossing biological and tumor-associated barriers. In this review, we underlined the potential of CAR-T-derived EVs as therapeutic agents in tumors.

Exosomal transmission of viruses, a two-edged biological sword

As a common belief, most viruses can egress from the host cells as single particles and transmit to uninfected cells. Emerging data have revealed en bloc viral transmission as lipid bilayer-cloaked particles via extracellular vesicles especially exosomes (Exo). The supporting membrane can be originated from multivesicular bodies during intra-luminal vesicle formation and autophagic response. Exo are nano-sized particles, ranging from 40-200 nm, with the ability to harbor several types of signaling molecules from donor to acceptor cells in a paracrine manner, resulting in the modulation of specific signaling reactions in target cells. The phenomenon of Exo biogenesis consists of multiple and complex biological steps with the participation of diverse constituents and molecular pathways. Due to similarities between Exo biogenesis and virus replication and the existence of shared pathways, it is thought that viruses can hijack the Exo biogenesis machinery to spread and evade immune cells. To this end, Exo can transmit complete virions (as single units or aggregates), separate viral components, and naked genetic materials. The current review article aims to scrutinize challenges and opportunities related to the exosomal delivery of viruses in terms of viral infections and public health. Video Abstract.

Small extracellular vesicle DNA-mediated horizontal gene transfer as a driving force for tumor evolution: Facts and riddles

The basis of the conventional gene-centric view on tumor evolution is that vertically inherited mutations largely define the properties of tumor cells. In recent years, however, accumulating evidence shows that both the tumor cells and their microenvironment may acquire external, non-vertically inherited genetic properties via horizontal gene transfer (HGT), particularly through small extracellular vesicles (sEVs). Many phases of sEV-mediated HGT have been described, such as DNA packaging into small vesicles, their release, uptake by recipient cells, and incorporation of sEV-DNA into the recipient genome to modify the phenotype and properties of cells. Recent techniques in sEV separation, genome sequencing and editing, as well as the identification of new secretion mechanisms, shed light on a number of additional details of this phenomenon. Here, we discuss the key features of this form of gene transfer and make an attempt to draw relevant conclusions on the contribution of HGT to tumor evolution.

Leishmania parasites exchange drug-resistance genes through extracellular vesicles

Leishmania are eukaryotic parasites that have retained the ability to produce extracellular vesicles (EVs) through evolution. To date, it has been unclear if different DNA entities could be associated with Leishmania EVs and whether these could constitute a mechanism of horizontal gene transfer (HGT). Herein, we investigate the DNA content of EVs derived from drug-resistant parasites, as well as the EVs' potential to act as shuttles for DNA transfer. Next-generation sequencing and PCR assays confirm the enrichment of amplicons carrying drug-resistance genes associated with EVs. Transfer assays of drug-resistant EVs highlight a significant impact on the phenotype of recipient parasites induced by the expression of the transferred DNA. Recipient parasites display an enhanced growth and better control of oxidative stress. We provide evidence that eukaryotic EVs function as efficient mediators in HGT, thereby facilitating the transmission of drug-resistance genes and increasing the fitness of cells when encountering stressful environments.

Extracellular vesicles from thyroid cancer harbor a functional machinery involved in extracellular matrix remodeling

Extracellular vesicles (EVs) participate in cell-stroma crosstalk within the tumor microenvironment and fibroblasts (Fb) contribute to tumor promotion in thyroid cancer. However, the role of tumor-stroma derived EVs still needs to be deciphered. We hypothesized that the interaction of thyroid tumor cells with Fb would liberate EVs with a specific proteomic profile, which would have an impact on EV-functionality in thyroid tumor progression-related events. Tumor (TPC-1, 8505c) and non-tumor (NThyOri) thyroid cells were co-cultured with human Fb. EVs, obtained by ultracentrifugation of conditioned media, were characterized by nanoparticle tracking analysis and western blotting. EV-proteomic analysis was performed by mass-spectrometry, and metalloproteinases (MMPs) were studied by zymography. EV-exchange was evaluated using immunofluorescence, confocal microscopy and FACS. EVs expressed classical exosome markers, with EVs from thyroid tumor cell-Fb co-cultures showing a proteomic profile related to extracellular matrix (ECM) remodeling. Bidirectional crosstalk between Fb and TPC-1 cells produced significantly more EVs than their isolated cells, and potentiated EV-functionality. In line with this, Fb-TPC-1 derived EVs induced MMP2 activation in NThyOri supernatants, and MMP2 activity could be evidenced in Fb and TPC-1 contact-independent co-cultures. Besides, MMP2 interactors allowed us to discriminate between EVs from thyroid tumoral and non-tumoral milieus. Interestingly, Fb internalized more EVs from TPC-1 than from NThyOri producing cells. Fb and thyroid tumor cell crosstalk produces specialized EVs with an ECM remodeling proteomic profile, enabling activation of MMP2 and possibly facilitating ECM-degradation, which is potentially linked with thyroid tumor progression.

Roles of Exosome Genomic DNA in Colorectal Cancer

Exosomes are extracellular vesicles that mediate cell-to-cell communication. Bioactive substances such as DNA, RNA, lipids, and proteins are present in it, and they play an essential role in the pathogenesis of colorectal cancer (CRC). The role of RNA and protein in exosomes has been extensively studied. Exosome DNA has recently attracted the attention of a great deal of scientists. According to studies, exosome DNA mainly contains genomic DNA (gDNA) and mitochondrial DNA (mtDNA), of which exosome gDNA is widely used in liquid biopsy of CRC. It includes a variety of clinically relevant tumor-specific mutation genes. In addition to liquid biopsy, researchers find that exosome gDNA regulates immune and metabolic functions in CRC, making it an important research object. However, the primary research on exosome gDNA is still limited. Here, we describe the occurrence and composition of exosomes. Summarize the essential characteristics and mode of action of exosome gDNA. Remarkably, this paper constitutes a comprehensive summary on the role of exosome gDNA on CRC with the intent of providing a theoretical basis and reference for early diagnosis and clinical treatment of cancer.

Contribution of Tumor-Derived Extracellular Vesicles to Malignant Transformation of Normal Cells

Tumor-cell-derived extracellular vesicles (EVs) are known to carry biologically active molecules of parental cells, which can actively modulate the tumor microenvironment. EVs produced by tumor cells play significant roles in the development and maintenance of tumor growth, metastasis, immune escape, and other important processes. However, the ability of EVs to induce the transformation of normal cells has hardly been investigated. This review discusses studies that describe the ability of tumor-cell-derived EVs to alter the metabolism and morphology of normal cells, causing changes associated with malignant transformation. Additionally, the horizontal transfer of oncogenes through EVs of tumor cells and the induction of epigenetic changes in normal cells, which leads to genomic instability and subsequent oncogenic transformation of normal cells, are also discussed.

Insight into Extracellular Vesicle-Cell Communication: From Cell Recognition to Intracellular Fate

Extracellular vesicles (EVs) are heterogamous lipid bilayer-enclosed membranous structures secreted by cells. They are comprised of apoptotic bodies, microvesicles, and exosomes, and carry a range of nucleic acids and proteins that are necessary for cell-to-cell communication via interaction on the cells surface. They initiate intracellular signaling pathways or the transference of cargo molecules, which elicit pleiotropic responses in recipient cells in physiological processes, as well as pathological processes, such as cancer. It is therefore important to understand the molecular means by which EVs are taken up into cells. Accordingly, this review summarizes the underlying mechanisms involved in EV targeting and uptake. The primary method of entry by EVs appears to be endocytosis, where clathrin-mediated, caveolae-dependent, macropinocytotic, phagocytotic, and lipid raft-mediated uptake have been variously described as being prevalent. EV uptake mechanisms may depend on proteins and lipids found on the surfaces of both vesicles and target cells. As EVs have been shown to contribute to cancer growth and progression, further exploration and targeting of the gateways utilized by EVs to internalize into tumor cells may assist in the prevention or deceleration of cancer pathogenesis.

Tumor-Derived Exosomes in Tumor-Induced Immune Suppression

Exosomes are a class of small membrane-bound extracellular vesicles released by almost all cell types and present in all body fluids. Based on the studies of exosome content and their interactions with recipient cells, exosomes are now thought to mediate “targeted” information transfer. Tumor-derived exosomes (TEX) carry a cargo of molecules different from that of normal cell-derived exosomes. TEX functions to mediate distinct biological effects such as receptor discharge and intercellular cross-talk. The immune system defenses, which may initially restrict tumor progression, are progressively blunted by the broad array of TEX molecules that activate suppressive pathways in different immune cells. Herein, we provide a review of the latest research progress on TEX in the context of tumor-mediated immune suppression and discuss the potential as well as challenges of TEX as a target of immunotherapy.

Protective effects of physical activity in colon cancer and underlying mechanisms: A review of epidemiological and biological evidence

Numerous epidemiological studies indicate that physical activity has a protective effect against colon cancer development and progression. Further, the relevant biological mechanisms where physical activity or exercise may improve survival have also been initially examined. In this review, we provide an overview of the epidemiological evidence to date which comprises 16 cohort studies of the effects of physical activity on colon cancer outcomes including cancer recurrence, cancer-specific and overall survival. Moreover, we present four potential mechanisms involving shear pressure, systemic milieu alteration, extracellular vesicles, and immune function by which physical activity and exercise may favorably impact colon cancer. Research currently in progress will provide definitive evidence of survival benefits resulting from exercise and future work will help clarify the role of targeted exercise and the relevant mechanisms involved.

Potential Role of Exercise Induced Extracellular Vesicles in Prostate Cancer Suppression

Physical exercise is increasingly recognized as a valuable treatment strategy in managing prostate cancer, not only enhancing supportive care but potentially influencing disease outcomes. However, there are limited studies investigating mechanisms of the tumor-suppressive effect of exercise. Recently, extracellular vesicles (EVs) have been recognized as a therapeutic target for cancer as tumor-derived EVs have the potential to promote metastatic capacity by transferring oncogenic proteins, integrins, and microRNAs to other cells and EVs are also involved in developing drug resistance. Skeletal muscle has been identified as an endocrine organ, releasing EVs into the circulation, and levels of EV-containing factors have been shown to increase in response to exercise. Moreover, preclinical studies have demonstrated the tumor-suppressive effect of protein and microRNA contents in skeletal muscle-derived EVs in various cancers, including prostate cancer. Here we review current knowledge of the tumor-derived EVs in prostate cancer progression and metastasis, the role of exercise in skeletal muscle-derived EVs circulating levels and the alteration of their contents, and the potential tumor-suppressive effect of skeletal muscle-derived EV contents in prostate cancer. In addition, we review the proposed mechanism of exercise in the uptake of skeletal muscle-derived EVs in prostate cancer.

Pancreatic Cancer Small Extracellular Vesicles (Exosomes): A Tale of Short- and Long-Distance Communication

Simple Summary

Even today, pancreatic cancer still has a dismal prognosis. It is characterized by a lack of early symptoms and thus late diagnosis as well as early metastasis. The majority of patients suffer from pancreatic ductal adenocarcinoma (PDAC). PDACs communicate extensively with cellular components of their microenvironment, but also with distant metastatic niches to facilitate tumor progression and dissemination. This crosstalk is substantially enabled by small extracellular vesicles (sEVs, exosomes) with a size of 30–150 nm that are released from the tumor cells. sEVs carry bioactive cargos that reprogram target cells to promote tumor growth, migration, metastasis, immune evasion, or chemotherapy resistance. Interestingly, sEVs also carry novel diagnostic, prognostic and potentially also predictive biomarkers. Moreover, engineered sEVs may be utilized as therapeutic agents, improving treatment options. The role of sEVs for PDAC development, progression, diagnosis, prognosis, and treatment is the focus of this review.

Abstract

Even with all recent advances in cancer therapy, pancreatic cancer still has a dismal 5-year survival rate of less than 7%. The most prevalent tumor subtype is pancreatic ductal adenocarcinoma (PDAC). PDACs display an extensive crosstalk with their tumor microenvironment (TME), e.g., pancreatic stellate cells, but also immune cells to regulate tumor growth, immune evasion, and metastasis. In addition to crosstalk in the local TME, PDACs were shown to induce the formation of pre-metastatic niches in different organs. Recent advances have attributed many of these interactions to intercellular communication by small extracellular vesicles (sEVs, exosomes). These nanovesicles are derived of endo-lysosomal structures (multivesicular bodies) with a size range of 30–150 nm. sEVs carry various bioactive cargos, such as proteins, lipids, DNA, mRNA, or miRNAs and act in an autocrine or paracrine fashion to educate recipient cells. In addition to tumor formation, progression, and metastasis, sEVs were described as potent biomarker platforms for diagnosis and prognosis of PDAC. Advances in sEV engineering have further indicated that sEVs might once be used as effective drug carriers. Thus, extensive sEV-based communication and applications as platform for biomarker analysis or vehicles for treatment suggest a major impact of sEVs in future PDAC research.

Small Extracellular Vesicles and Metastasis-Blame the Messenger

Simple Summary

Due to their systemic nature, metastatic lesions are a major problem for curative cancer treatment. According to a common model for metastasis, tumor cells disseminate by local invasion, survival in the blood stream and extravasation into suitable tissue environments. At secondary sites, metastatic cells adapt, proliferate and foster vascularization to satisfy nutrient and oxygen demand. In recent years, tumors were shown to extensively communicate with cells in the local microenvironment and future metastatic sites by secreting small extracellular vesicles (sEVs, exosomes). sEVs deliver bioactive cargos, e.g., proteins, and in particular, several nucleic acid classes to reprogram target cells, which in turn facilitate tumor growth, cell motility, angiogenesis, immune evasion and establishment of pre-metastatic niches. sEV-cargos also act as biomarkers for diagnosis and prognosis. This review discusses how tumor cells utilize sEVs with nucleic acid cargos to progress through metastasis, and how sEVs may be employed for prognosis and treatment.

Abstract

Cancer is a complex disease, driven by genetic defects and environmental cues. Systemic dissemination of cancer cells by metastasis is generally associated with poor prognosis and is responsible for more than 90% of cancer deaths. Metastasis is thought to follow a sequence of events, starting with loss of epithelial features, detachment of tumor cells, basement membrane breakdown, migration, intravasation and survival in the circulation. At suitable distant niches, tumor cells reattach, extravasate and establish themselves by proliferating and attracting vascularization to fuel metastatic growth. These processes are facilitated by extensive cross-communication of tumor cells with cells in the primary tumor microenvironment (TME) as well as at distant pre-metastatic niches. A vital part of this communication network are small extracellular vesicles (sEVs, exosomes) with a size of 30–150 nm. Tumor-derived sEVs educate recipient cells with bioactive cargos, such as proteins, and in particular, major nucleic acid classes, to drive tumor growth, cell motility, angiogenesis, immune evasion and formation of pre-metastatic niches. Circulating sEVs are also utilized as biomarker platforms for diagnosis and prognosis. This review discusses how tumor cells facilitate progression through the metastatic cascade by employing sEV-based communication and evaluates their role as biomarkers and vehicles for drug delivery.

Extracellular Vesicles in Advanced Prostate Cancer: Tools to Predict and Thwart Therapeutic Resistance

Prostate cancer (PCa) is the second most frequent cancer and the fifth leading cause of cancer death among men worldwide. At first, advanced PCa is treated by androgen deprivation therapy with a good initial response. Nevertheless, recurrences occur, leading to Castrate-Resistance Prostate Cancer (CRPC). During the last decade, new therapies based on inhibition of the androgen receptor pathway or taxane chemotherapies have been used to treat CRPC patients leading to an increase in overall survival, but the occurrence of resistances limits their benefits. Numerous studies have demonstrated the implication of extracellular vesicles (EVs) in different cancer cellular mechanisms. Thus, the possibility to isolate and explore EVs produced by tumor cells in plasma/sera represents an important opportunity for the deciphering of those mechanisms and the discovery of biomarkers. Herein, we summarized the role of EVs in therapeutic resistance of advanced prostate cancer and their use to find biomarkers able to predict these resistances.

Fostering "Education": Do Extracellular Vesicles Exploit Their Own Delivery Code?

Extracellular vesicles (EVs), comprising large microvesicles (MVs) and exosomes (EXs), play a key role in intercellular communication, both in physiological and in a wide variety of pathological conditions. However, the education of EV target cells has so far mainly been investigated as a function of EX cargo, while few studies have focused on the characterization of EV surface membrane molecules and the mechanisms that mediate the addressability of specific EVs to different cell types and tissues. Identifying these mechanisms will help fulfill the diagnostic, prognostic, and therapeutic promises fueled by our growing knowledge of EVs. In this review, we first discuss published studies on the presumed EV “delivery code” and on the combinations of the hypothesized EV surface membrane “sender” and “recipient” molecules that may mediate EV targeting in intercellular communication. Then we briefly review the main experimental approaches and techniques, and the bioinformatic tools that can be used to identify and characterize the structure and functional role of EV surface membrane molecules. In the final part, we present innovative techniques and directions for future research that would improve and deepen our understandings of EV-cell targeting.

Pro-Inflammatory Microenvironment Modulates the Transfer of Mutated TP53 Mediated by Tumor Exosomes

Exosomes released from tumor cells are instrumental in shaping the local tumor microenvironment to allow cancer progression. Recently, it has been shown that tumor exosomes carry large fragments of dsDNA, which may reflect the mutational status of parental cells. Although it has been described that a stressful microenvironment can influence exosomal cargo, the effects on DNA packing and its transfer into recipient cells have yet to be investigated. Here, we report that exosomes derived from SW480 (human colorectal adenocarcinoma cell line) cells can carry dsDNA fragments containing the entire coding sequence of both TP53 and KRAS genes, harboring the SW480-related TP53 c.818G > A and KRAS c.35G > T typical mutations. We also report the following: that cell stimulation with lipopolysaccharides (LPS) promotes the selective packaging of the TP53 gene, but not the KRAS gene; that exosomes secreted by SW480 cells efficiently transfer the mutated sequences into normal CCD841-CoN colon epithelial and THLE-2 hepatic cells; that this mechanism is more efficient when the cells had been previously incubated with pro-inflammatory cytokines; that the TP53 gene appears actively transcribed in both recipient cells; and that mutated mRNA levels are not influenced by cytokine treatment. Our data strongly suggest that pro-inflammatory stimulation promotes the horizontal transfer of an oncogene by exosomes, although this remains a rare event. Further studies are needed to assess the impact of the oncogenic transfer by exosomes in malignant transformation and its role in tumor progression.

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

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

The Nexus of cfDNA and Nuclease Biology

Cell-free DNA (cfDNA) is a widely used noninvasive biomarker for diagnosis and prognosis of multiple disease states. Emerging evidence suggests that cfDNA might not just be passive waste products of cell death but could have a physiological and pathological function in inflammation and autoimmunity. The balance of cfDNA generation and clearance may thus be vital in health and disease. In particular, plasma nuclease activity has been linked to multiple pathologies including cancer and systemic lupus erythematosus (SLE) and associated with profound changes in the nonrandom fragmentation of cfDNA. Lastly, in this review, we explore the effects of DNA fragmentation factor B (DFFB), DNASE1L3, and DNASE1 on cfDNA levels and their fragmentomic profiles, and what these recent insights reveal about the biology of cfDNA.

Extracellular Vesicle Mediated Vascular Pathology in Glioblastoma

Glioblastoma (GBM) is an incurable, infiltrative high-grade brain tumour associated with dramatic vascular responses observed both locally (angiogenesis, vascular cooption, angiocrine effects, microthrombosis) and systemically (venous thromboembolism). GBM-associated vascular pathology is diagnostically relevant and constitutes a source of morbidity, mortality and progressive changes in tumour biology. Extracellular vesicles (EVs) have emerged as unique mediators of vascular effects in brain tumours acting as vehicles for intercellular transfer of oncoproteins (e.g. EGFRvIII), RNA, DNA and molecular effectors of angiogenesis and thrombosis. Vascular effects of GBM EVs are regulated by cancer cell genome, epigenome and microenvironment and differ between subtypes of cancer cells and stem cells. Understanding and targeting EV-driven vascular processes in GBM may offer new approaches to diagnose and treat these intractable tumours.

The forces driving cancer extracellular vesicle secretion

The discovery that cancer cells discharge vast quantities of extracellular vesicles (EVs), underscored the explosion of the EV field. A large body of evidence now supports their onco-functionality in an array of contexts; stromal crosstalk, immune evasion, metastatic site priming, and drug resistance - justifying therapeutic intervention. The current bottleneck is a lack of clear understanding of why and how EV biogenesis ramps up in cancer cells, and hence where exactly avenues for intervention may reside. We know that EVs also play an array of physiological roles, therefore effective anticancer inhibition requires a target distinct enough from physiology to achieve efficacy. Taking the perspective that EV upregulation may be a consequence of the tumor landscape, we examine classic mutational events and tumor characteristics for EV regulators. All the while, aiming to illuminate topics worth further research in therapeutic development.

Extracellular Vesicle-Mediated Bilateral Communication between Glioblastoma and Astrocytes

Glioblastoma the most aggressive form of brain cancer, comprises a complex mixture of tumor cells and nonmalignant stromal cells, including neurons, astrocytes, microglia, infiltrating monocytes/macrophages, lymphocytes, and other cell types. All nonmalignant cells within and surrounding the tumor are affected by the presence of glioblastoma. Astrocytes use multiple modes of communication to interact with neighboring cells. Extracellular vesicle-directed intercellular communication has been found to be an important component of signaling between astrocytes and glioblastoma in tumor progression. In this review, we focus on recent findings on extracellular vesicle-mediated bilateral crosstalk, between glioblastoma cells and astrocytes, highlighting the protumor and antitumor roles of astrocytes in glioblastoma development.

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

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

Uveal Melanoma-Derived Extracellular Vesicles Display Transforming Potential and Carry Protein Cargo Involved in Metastatic Niche Preparation

Extracellular vesicles (EVs) carry molecules derived from donor cells and are able to alter the properties of recipient cells. They are important players during the genesis and progression of tumors. Uveal melanoma (UM) is the most common primary intraocular tumor in adults and is associated with a high rate of metastasis, primarily to the liver. However, the mechanisms underlying this process are poorly understood. In the present study, we analyzed the oncogenic potential of UM-derived EVs and their protein signature. We isolated and characterized EVs from five UM cell lines and from normal choroidal melanocytes (NCMs). BRCA1-deficient fibroblasts (Fibro-BKO) were exposed to the EVs and analyzed for their growth in vitro and their reprograming potential in vivo following inoculation into NOD-SCID mice. Mass spectrometry of proteins from UM-EVs and NCM-EVs was performed to determine a protein signature that could elucidate potential key players in UM progression. In-depth analyses showed the presence of exosomal markers, and proteins involved in cell-cell and focal adhesion, endocytosis, and PI3K-Akt signaling pathway. Notably, we observed high expression levels of HSP90, HSP70 and integrin V in UM-EVs. Our data bring new evidence on the involvement of UM-EVs in cancer progression and metastasis.

Extracellular Vesicles as Innovative Tool for Diagnosis, Regeneration and Protection against Neurological Damage

Extracellular vesicles (EVs) have recently attracted a great deal of interest as they may represent a new biosignaling paradigm. According to the mode of biogenesis, size and composition, two broad categories of EVs have been described, exosomes and microvesicles. EVs have been shown to carry cargoes of signaling proteins, RNA species, DNA and lipids. Once released, their content is selectively taken up by near or distant target cells, influencing their behavior. Exosomes are involved in cell–cell communication in a wide range of embryonic developmental processes and in fetal–maternal communication. In the present review, an outline of the role of EVs in neural development, regeneration and diseases is presented. EVs can act as regulators of normal homeostasis, but they can also promote either neuroinflammation/degeneration or tissue repair in pathological conditions, depending on their content. Since EV molecular cargo constitutes a representation of the origin cell status, EVs can be exploited in the diagnosis of several diseases. Due to their capability to cross the blood–brain barrier (BBB), EVs not only have been suggested for the diagnosis of central nervous system disorders by means of minimally invasive procedures, i.e., “liquid biopsies”, but they are also considered attractive tools for targeted drug delivery across the BBB. From the therapeutic perspective, mesenchymal stem cells (MSCs) represent one of the most promising sources of EVs. In particular, the neuroprotective properties of MSCs derived from the dental pulp are here discussed.

The Role of Cancer-Associated Fibroblasts and Extracellular Vesicles in Tumorigenesis

Extracellular vesicles (EVs) play a key role in the communication between cancer cells and stromal components of the tumor microenvironment (TME). In this context, cancer cell-derived EVs can regulate the activation of a CAF phenotype in TME cells, which can be mediated by several EV cargos (e.g., miRNA, proteins, mRNA and lncRNAs). On the other hand, CAF-derived EVs can mediate several processes during tumorigenesis, including tumor growth, invasion, metastasis, and therapy resistance. This review aimed to discuss the molecular aspects of EV-based cross-talk between CAFs and cancer cells during tumorigenesis, in addition to assessing the roles of EV cargo in therapy resistance and pre-metastatic niche formation.

Large Extracellular Vesicles-A New Frontier of Liquid Biopsy in Oncology

Extracellular Vesicles (EVs) are emerging as pivotal elements in cancer. Many studies have focused on the role of Small- (S)-EVs but in recent years Large-(L)-EVs have progressively gained increasing interest due to their peculiar content and functions. Tumor-derived L-EVs carry a lot of oncogenic proteins, nucleic acids and lipids to recipient cells and are involved in the reshaping of the tumor microenvironment as well as in the metabolic rewiring and the promotion of the pro-metastatic attitude of cancer cells. Several techniques have been developed for the isolation of L-EVs and commercial kits are also available for efficient and easy recovery of these vesicles. Also, the improvement in DNA sequencing and “omics sciences” profoundly changed the way to analyze and explore the molecular content of L-EVs, thus providing novel and potentially useful cancer biomarkers. Herein, we review the most recent findings concerning the role of L-EVs in cancer and discuss their possible use in oncology as “liquid biopsy” tools as compared to the other classes of EVs.

DNA in extracellular vesicles: biological and clinical aspects

The study of extracellular vesicles (EVs), especially in the liquid biopsy field, has rapidly evolved in recent years. However, most EV studies have focused on RNA or protein content and DNA in EVs (EV‐DNA) has largely been unnoticed. In this review, we compile current evidence regarding EV‐DNA and provide an extensive discussion on EV‐DNA biology. We look into EV‐DNA biogenesis and mechanisms of DNA loading into EVs, as well as describe the particularly significant function of DNA‐carrying EVs in the maintenance of cellular homeostasis, intracellular communication, and immune response modulation. We also examine the current role of EV‐DNA in the clinical setting, specifically in cancer, infections, pregnancy, and prenatal diagnosis.

Liquid Biopsy in Uveal Melanoma: Are We There Yet?

In the era of precision oncology, major strides are being made to use individual tumor information for clinical decision-making. Differing from traditional biopsy methods, the emerging practice of liquid biopsy provides a minimally invasive way of obtaining tumor cells and derived molecules. Liquid biopsy provides a means to detect and monitor disease progression, recurrence, and treatment response in a noninvasive way, and to potentially complement classical biopsy. Uveal melanoma (UM) is a unique malignancy, with diagnosis heavily reliant on imaging, few repeat biopsies, and a high rate of metastasis, which occurs hematogenously and often many years after diagnosis. In this disease setting, a noninvasive biomarker to detect, monitor, and study the disease in real time could lead to better disease understanding and patient care. While advances have been made in the detection of tumor-disseminated components, sensitivity and specificity remain important challenges. Ambiguity remains in how to interpret current findings and in how liquid biopsy can have a place in clinical practice. Related publications in UM are few compared to other cancers, but with further studies we may be able to uncover more about the biology of disseminated molecules and the mechanisms involved in the progression to metastasis.

Tumor-Derived Exosomes in Immunosuppression and Immunotherapy

Tumor-derived exosomes (TEX) are involved in cancer development, metastasis, and disease progression. They can modulate angiogenesis to elevate the malignant degree of tumor cells. TEX carry immunosuppressive factors affecting the antitumor activities of immune cells. Tumor cells as well as immune cells secrete immunologically active exosomes which affect intercellular communication, antigen presentation, activation of immune cells, and immune surveillance. Cell proliferation and immune response suppression create a favorable microenvironment for tumor. TEX can inhibit immune cell proliferation, induce apoptosis of activated CD8+ Teffs, suppress NK cell activity, interfere with monocyte differentiation, and promote Treg as well as MDSC expansion. Exosomes of microenvironment cells may also contribute to the development of drug resistance in cancer therapy. An important role of TEX in modulating the sensitivity of tumor cells to immunotherapy is a promising area of research to make the cancer therapy more successful.

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

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

Cell Surface Labeling by Engineered Extracellular Vesicles

Extracellular vesicles (EVs) can mediate local and long-range intercellular communication via cell surface signaling. In order to perform in vivo studies of unmanipulated, endogenously released EVs, sensitive but stringent approaches able to detect EV-cell surface interactions are needed. However, isolation and reinfusion of EVs can introduce biases. A rigorous way to study EVs in vivo is by genetically engineering membrane-bound reporters into parental cells. Still, the amount of reporter molecules that EVs can carry is relatively small, and thus, the sensitivity of the approach is suboptimal. This work addresses this issue by engineering EVs to display a membrane-bound form of Sortase A (SrtA), a bacterial transpeptidase that can catalyze the transfer of reporter molecules on the much bigger surface of EV-binding cells. SrtA design and reaction requirements are optimized and validated. Efficient in vitro labeling of EV-binding cells is achieved, even in the presence of only one N-terminal glycine on cell surface proteins. As compared to indirect labeling of EV-binding cells (e.g., using CD63-GFP fusion), the SrtA-based approach shows 1-2 log increase in sensitivity, depending on the EV source. This novel approach will be useful to identify and study the full set of host cells interacting with native EVs in vivo.

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

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

Current Knowledge and Future Perspectives on Mesenchymal Stem Cell-Derived Exosomes as a New Therapeutic Agent

Mesenchymal stem cells (MSCs) are on the cusp of regenerative medicine due to their differentiation capacity, favorable culture conditions, ability to be manipulated in vitro, and strong immunomodulatory activity. Recent studies indicate that the pleiotropic effects of MSCs, especially their immunomodulatory potential, can be largely attributed to paracrine factors. Exosomes, vesicles that are 30-150 nanometers in diameter that function in cell-cell communication, are one of the key paracrine effectors. MSC-derived exosomes are enriched with therapeutic miRNAs, mRNAs, cytokines, lipids, and growth factors. Emerging evidences support the compelling possibility of using MSC-derived exosomes as a new form of therapy for treating several different kinds of disease such as heart, kidney, immune diseases, neural injuries, and neurodegenerative disease. This review provides a summary of current knowledge and discusses engineering of MSC-derived exosomes for their use in translational medicine.

Phenotypic Switching of Naïve T Cells to Immune-Suppressive Treg-Like Cells by Mutant KRAS

Oncogenic (mutant) Ras protein Kirsten rat sarcoma viral oncogene homolog (KRAS) promotes uncontrolled proliferation, altered metabolism, and loss of genome integrity in a cell-intrinsic manner. Here, we demonstrate that CD4⁺ T cells when incubated with tumor-derived exosomes from mutant (MT) KRAS non-small-cell lung cancer (NSCLC) cells, patient sera, or a mouse xenograft model, induce phenotypic conversion to FOXP3⁺ Treg-like cells that are immune-suppressive. Furthermore, transfecting T cells with MT KRAS cDNA alone induced phenotypic switching and mathematical modeling supported this conclusion. Single-cell sequencing identified the interferon pathway as the mechanism underlying the phenotypic switch. These observations highlight a novel cytokine-independent, cell-extrinsic role for KRAS in T cell phenotypic switching. Thus, targeting this new class of Tregs represents a unique therapeutic approach for NSCLC. Since KRAS is the most frequently mutated oncogene in a wide variety of cancers, the findings of this investigation are likely to be of broad interest and have a large scientific impact.

Tumor-derived extracellular vesicles: molecular parcels that enable regulation of the immune response in cancer

Extracellular vesicles (EVs) are a heterogeneous collection of membrane-bound vesicles released by cells that contain bioactive cargoes including proteins, lipids and nucleic acids. Multiple subpopulations of EVs have now been recognized and these include exosomes and microvesicles. EVs have been thought to facilitate intercellular and distal communication to bring about various processes that enable tumor progression and metastases. Here, we describe the current knowledge of the functional cargo contained within EVs, with a focus on tumor microvesicles, and review the emerging theory of how EVs support immune suppression in cancer.

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

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

Enhancement of therapeutic potential of mesenchymal stem cell-derived extracellular vesicles

After the initial investigations into applications of mesenchymal stem cells (MSCs) for cell therapy, there was increased interest in their secreted soluble factors. Following studies of MSCs and their secreted factors, extracellular vesicles (EVs) released from MSCs have emerged as a new mode of intercellular crosstalk. MSC-derived EVs have been identified as essential signaling mediators under both physiological and pathological conditions, and they appear to be responsible for many of the therapeutic effects of MSCs. In several in vitro and in vivo models, EVs have been observed to have supportive functions in modulating the immune system, mainly mediated by EV-associated proteins and nucleic acids. Moreover, stimulation of MSCs with biophysical or biochemical cues, including EVs from other cells, has been shown to influence the contents and biological activities of subsequent MSC-derived EVs. This review provides on overview of the contents of MSC-derived EVs in terms of their supportive effects, and it provides different perspectives on the manipulation of MSCs to improve the secretion of EVs and subsequent EV-mediated activities. In this review, we discuss the possibilities for manipulating MSCs for EV-based cell therapy and for using EVs to affect the expression of elements of interest in MSCs. In this way, we provide a clear perspective on the state of the art of EVs in cell therapy focusing on MSCs, and we raise pertinent questions and suggestions for knowledge gaps to be filled.

Cell Intrinsic and Extrinsic Mechanisms of Caveolin-1-Enhanced Metastasis

Caveolin-1 (CAV1) is a scaffolding protein with a controversial role in cancer. This review will initially discuss earlier studies focused on the role as a tumor suppressor before elaborating subsequently on those relating to function of the protein as a promoter of metastasis. Different mechanisms are summarized illustrating how CAV1 promotes such traits upon expression in cancer cells (intrinsic mechanisms). More recently, it has become apparent that CAV1 is also a secreted protein that can be included into exosomes where it plays a significant role in determining cargo composition. Thus, we will also discuss how CAV1 containing exosomes from metastatic cells promote malignant traits in more benign recipient cells (extrinsic mechanisms). This ability appears, at least in part, attributable to the transfer of specific cargos present due to CAV1 rather than the transfer of CAV1 itself. The evolution of how our perception of CAV1 function has changed since its discovery is summarized graphically in a time line figure.

Intercellular Transfer of Oncogenic KRAS via Tunneling Nanotubes Introduces Intracellular Mutational Heterogeneity in Colon Cancer Cells

Mutated forms of the RAS oncogene drive 30% of all cancers, but they cannot be targeted therapeutically using currently available drugs. The molecular and cellular mechanisms that create a heterogenous tumor environment harboring both mutant and wild-type RAS have not been elucidated. In this study, we examined horizontal transfer of mutant KRAS between colorectal cancer (CRC) cells via a direct form of cell-to-cell communication called tunneling nanotubes (TNTs). TNT formation was significantly higher in CRC cell lines expressing mutant KRAS than CRC cell lines expressing wild-type RAS; this effect was most pronounced in metastatic CRC cell lines with both mutant KRAS and deficiency in mismatch repair proteins. Using inverted and confocal fluorescence time-lapse and fluorescence recovery after photobleaching (FRAP)-based microscopy, we observed GFP-tagged mutant KRAS^G12D protein trafficking between CRC cells through TNTs within a span of seconds to several minutes. Notably, acquisition of mutant KRAS increased Extracellular Signal-regulated Kinase (ERK) phosphorylation and upregulated tunneling nanotube formation in recipient wildtype CRC cells. In conclusion, these findings suggest that intercellular horizontal transfer of RAS can occur by TNTs. We propose that intercellular transfer of mutant RAS can potentially induce intratumoral heterogeneity and result in a more invasive phenotype in recipient cells.

Extracellular vesicles in cancer - implications for future improvements in cancer care

The sustained growth, invasion, and metastasis of cancer cells depend upon bidirectional cell-cell communication within complex tissue environments. Such communication predominantly involves the secretion of soluble factors by cancer cells and/or stromal cells within the tumour microenvironment (TME), although these cell types have also been shown to export membrane-encapsulated particles containing regulatory molecules that contribute to cell-cell communication. These particles are known as extracellular vesicles (EVs) and include species of exosomes and shed microvesicles. EVs carry molecules such as oncoproteins and oncopeptides, RNA species (for example, microRNAs, mRNAs, and long non-coding RNAs), lipids, and DNA fragments from donor to recipient cells, initiating profound phenotypic changes in the TME. Emerging evidence suggests that EVs have crucial roles in cancer development, including pre-metastatic niche formation and metastasis. Cancer cells are now recognized to secrete more EVs than their nonmalignant counterparts, and these particles can be isolated from bodily fluids. Thus, EVs have strong potential as blood-based or urine-based biomarkers for the diagnosis, prognostication, and surveillance of cancer. In this Review, we discuss the biophysical properties and physiological functions of EVs, particularly their pro-metastatic effects, and highlight the utility of EVs for the development of cancer diagnostics and therapeutics.

Advances in therapeutic applications of extracellular vesicles

Extracellular vesicles (EVs) are nanometer-sized, lipid membrane-enclosed vesicles secreted by most, if not all, cells and contain lipids, proteins, and various nucleic acid species of the source cell. EVs act as important mediators of intercellular communication that influence both physiological and pathological conditions. Given their ability to transfer bioactive components and surmount biological barriers, EVs are increasingly being explored as potential therapeutic agents. EVs can potentiate tissue regeneration, participate in immune modulation, and function as potential alternatives to stem cell therapy, and bioengineered EVs can act as delivery vehicles for therapeutic agents. Here, we cover recent approaches and advances of EV-based therapies.

Life and death of circulating cell-free DNA

Tumor-specific, circulating cell-free DNA in liquid biopsies is a promising source of biomarkers for minimally invasive serial monitoring of treatment responses in cancer management. We will review the current understanding of the origin of circulating cell-free DNA and different forms of DNA release (including various types of cell death and active secretion processes) and clearance routes. The dynamics of extracellular DNA in blood during therapy and the role of circulating DNA in pathophysiological processes (tumor-associated inflammation, NETosis, and pre-metastatic niche development) provide insights into the mechanisms that contribute to tumor development and metastases formation. Better knowledge of circulating tumor-specific cell-free DNA could facilitate the development of new therapeutic and diagnostic options for cancer management.

Mechanisms associated with biogenesis of exosomes in cancer

Intercellular communication between cellular compartments within the tumor and at distant sites is critical for the development and progression of cancer. Exosomes have emerged as potential regulators of intracellular communication in cancer. Exosomes are nanovesicles released by cells that contain biomolecules and are exchanged between cells. Exchange of exosomes between cells has been implicated in a number of processes critical for tumor progression and consequently altering exosome release is an attractive therapeutic target. Here, we review current understanding as well as gaps in knowledge regarding regulators of exosome release in cancer.

Systems biology approaches to investigating the roles of extracellular vesicles in human diseases

Extracellular vesicles (EVs) are membrane-enclosed structures secreted by cells. In the past decade, EVs have attracted substantial attention as carriers of complex intercellular information. They have been implicated in a wide variety of biological processes in health and disease. They are also considered to hold promise for future diagnostics and therapy. EVs are characterized by a previously underappreciated heterogeneity. The heterogeneity and molecular complexity of EVs necessitates high-throughput analytical platforms for detailed analysis. Recently, mass spectrometry, next-generation sequencing and bioinformatics tools have enabled detailed proteomic, transcriptomic, glycomic, lipidomic, metabolomic, and genomic analyses of EVs. Here, we provide an overview of systems biology experiments performed in the field of EVs. Furthermore, we provide examples of how in silico systems biology approaches can be used to identify correlations between genes involved in EV biogenesis and human diseases. Using a knowledge fusion system, we investigated whether certain groups of proteins implicated in the biogenesis/release of EVs were associated with diseases and phenotypes. Furthermore, we investigated whether these proteins were enriched in publicly available transcriptomic datasets using gene set enrichment analysis methods. We found associations between key EV biogenesis proteins and numerous diseases, which further emphasizes the key role of EVs in human health and disease.

Extracellular Vesicles: Mechanisms in Human Health and Disease

SIGNIFICANCE

Secreted extracellular vesicles (EVs) are now considered veritable entities for diagnosis, prognosis, and therapeutics. These structures are able to interact with target cells and modify their phenotype and function. Recent Advances: Since composition of EVs depends on the cell type of origin and the stimulation that leads to their release, the analysis of EV content remains an important input to understand the potential effects of EVs on target cells.

CRITICAL ISSUES

Here, we review recent data related to the mechanisms involved in the formation of EVs and the methods allowing specific EV isolation and identification. Also, we analyze the potential use of EVs as biomarkers in different pathologies such as diabetes, obesity, atherosclerosis, neurodegenerative diseases, and cancer. Besides, their role in these diseases is discussed. Finally, we consider EVs enriched in microRNA or drugs as potential therapeutic cargo able to deliver desirable information to target cells/tissues.

FUTURE DIRECTIONS

We underline the importance of the homogenization of the parameters of isolation of EVs and their characterization, which allow considering EVs as excellent biomarkers for diagnosis and prognosis.