Extracellular Vesicles and Metastasis

Extracellular vesicles as therapeutic modulators of neuroinflammation in Alzheimer's disease: a focus on signaling mechanisms

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) plaques and tau tangles, which contribute significantly to neuroinflammation, a central driver of disease pathogenesis. The activation of microglia and astrocytes, coupled with the complex interactions between Aβ and tau pathologies and the innate immune response, leads to a cascade of inflammatory events. This process triggers the release of pro-inflammatory cytokines and chemokines, exacerbating neuronal damage and fostering a cycle of chronic inflammation that accelerates neurodegeneration. Key signaling pathways, such as nuclear factor-kappa B (NF-κB), Janus kinase/signal transducer and activator of transcription (JAK/STAT), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), are involved in regulating the production of these inflammatory mediators, offering potential therapeutic targets for AD. Recently, extracellular vesicles (EVs) have emerged as a promising tool for AD therapy, due to their ability to cross the blood-brain barrier (BBB) and deliver therapeutic agents. Despite challenges in standardizing EV-based therapies and ensuring their safety, EVs offer a novel approach to modulating neuroinflammation and promoting neuroregeneration. This review aims to highlight the intricate relationship between neuroinflammation, signaling pathways, and the emerging role of EV-based therapeutics in advancing AD treatment strategies.

Peritoneal adipose stem cell-derived extracellular vesicles mediate the regulation of ovarian cancer cell proliferation and migration through EGFR-NF-κB signaling

Peritoneal dissemination frequently develops in patients with ovarian cancer (OC) and is associated with recurrence and metastasis. However, the cellular components and mechanisms supporting OC peritoneal metastasis are poorly understood. To elucidate these, we utilized RNA sequencing to investigate the cellular composition and function. Insights from transcriptome analyses suggested that OC cells from malignant ascites persisted in a quiescent state of low metabolic activity and after metastases to the peritoneum, arrested OC cells were reactivated and induced back to the cell cycle, suggesting that the peritoneum served as a favor tumor microenvironment. To elucidate the mechanisms, we then developed long-range migration and competitive inhibition assays and showed that peritoneal adipose-derived stem cells-derived extracellular vesicles (ADSCs-EVs) mediated preferential migration of OC cells toward peritoneal ADSCs but not other representative cells from the peritoneal cavity. In line with phenotypic changes, transcriptomic analysis revealed that patient peritoneal ADSCs-EVs stimulated the expression of numerous genes associated with OC cell proliferation and migration; among them, the epidermal growth factor receptor (EGFR) and nuclear factor kappa B (NF-κB) signaling pathways were highly enriched. We also found that peritoneal ADSCs produced and secreted key EGFR signaling molecules, including EGF and EGFR, into ADSCs-EVs. Upon fusion with OC cells, ADSCs-EVs up-regulated the EGFR-NF-κB axis and promoted OC cell proliferation and migration. Interference with either ADSCs-EVs production or EGFR signaling abolished the proliferation and migration effect. The results show that ADSCs modulate OC cell proliferation and migration at multiple layers, constituting a key mechanism in OC progression.

Extracellular vesicles: from intracellular trafficking molecules to fully fortified delivery vehicles for cancer therapeutics

Extracellular vesicles (EVs) are emerging as viable tools in cancer treatment due to their ability to carry a wide range of theranostic activities. This review summarizes different forms of EVs such as exosomes, microvesicles, apoptotic bodies, and oncosomes. It also sheds the light onto isolation methodologies, characterization techniques and therapeutic applications of all discussed EVs. Evidence indicates that EVs are particularly effective in delivering chemotherapeutic medications, and immunomodulatory agents. However, the advancement of EV-based therapies into clinical practice is hindered by challenges including EVs heterogeneity, cargo loading efficiency, and in vivo stability. Overall, EVs have the potential to change cancer therapeutic paradigms. Continued research and development activities are critical for improving EV-based medications and increasing their therapeutic impact.

Biogenesis and functional implications of extracellular vesicles in cancer metastasis

Extracellular vesicles (EVs) play a crucial role in the complex process of cancer metastasis by facilitating cellular communication and influencing the microenvironment to promote the spread and establishment of cancer cells in distant locations. This paper explores the process of EV biogenesis, explaining their various sources that range from endosomal compartments to plasma membrane shedding. It also discusses the complex mechanisms that control the sorting of cargo within EVs, determining their chemical makeup. We investigate the several functions of EVs in promoting the spread of cancer to other parts of the body. These functions include influencing the immune system, creating environments that support the formation of metastases before they occur, and aiding in the transformation of cells from an epithelial to a mesenchymal state. Moreover, we explore the practical consequences of EV cargo, such as nucleic acids, proteins, and lipids, in influencing the spread of cancer cells, from the beginning of invasion to the creation of secondary tumor sites. Examining recent progress in the field of EV-based diagnostics and treatments, we explore the potential of EVs as highly promising biomarkers for predicting the course of cancer and as targets for therapeutic intervention. This review aims to provide a complete understanding of the biology of EVs in the context of cancer metastasis. By unravelling the nuances of EV biology, it seeks to pave the way for new tactics in cancer detection, treatment, and management.

Tumor-derived exosomes: Unravelling the pathogenesis of pancreatic cancer with liver metastases and exploring the potential for clinical translation

Pancreatic cancer (PC) is one of the most malignant solid cancers, and PC metastasis, particularly liver metastasis, is a major cause of cancer mortality. A key event in tumor metastasis is the formation of pre-metastatic niche (PMN), which provides a microenvironment conducive to tumor cells colonization and progression. Various molecules loaded in tumor-derived exosomes (TDEs) contribute to PMN formation and distant tumor metastasis, by regulating immune and stromal cell function, inducing angiogenesis, and promoting metabolic reprogramming. Therefore, therapies targeting PMN may offer novel advantages to prevent tumor metastasis at an earlier stage. In this review, we summarize multifaceted mechanisms underlying hepatic PMN formation, with a focus on how PC TDEs participate in angiogenesis and vascular permeability, create immune suppressive microenvironment, remodel the extracellular matrix, and regulate metabolic reprogramming. In addition, we highlight the promise of TDEs for early diagnosis and effective therapy of PC liver metastases.

Chronic hypoxia for the adaptation of extracellular vesicle phenotype

Variations in oxygen level affect the phenotype of cells and extracellular vesicles (EVs). Depending on the metabolic oxygen demand of cells, hypoxic cell culture can produce conditions more like those found in vivo, and with appropriate oxygen levels, mimic hypoxic tumours. However, most previous experiments studying both EVs and the effects of hypoxia on cells use periods of 72 h or less of hypoxia. We hypothesised that this was insufficient time for adaptation to hypoxic conditions both for EVs and cells which may skew the results of such studies. In this study, the effects of acute (72 h) and chronic hypoxia (> 2 weeks) on the phenotype of HepG2 and PC3 cells and their EVs were examined. Cells could be cultured normally under chronic hypoxic conditions and cryopreserved and recovered. The effects of hypoxia on EV phenotype are slow to establish and dependent on cell line. In PC3 cells, the greatest change in phenotype and increase in EV production occurred only with chronic hypoxic culture. In HepG2 cells, the number of EVs produced was insensitive to hypoxic culture and the greatest changes in protein expression were observed after acute hypoxic culture. Nonetheless, biphasic changes in EV phenotype were detected in both cell types in response to either acute or chronic hypoxia. These results indicate that for cells which do not induce consumptive oxygen depletion, prolonged hypoxic culture is required for complete adaptation.

The role of extracellular vesicles in cancer

Extracellular vesicles (EVs), which include small EVs such as exosomes, play a critical role in intercellular communication and are produced by both cancer and non-cancer cells. Several studies have shown that cancer cells exploit various strategies to regulate the biogenesis, composition, and functions of EVs primarily to promote cancer progression. Given that exosomes originate from major sorting hubs at the limiting membrane of endosomes, they are central to a signaling network that connects external stimuli with intrinsic tumor cell features. Exosomes contain diverse repertoires of molecular cargos, such as proteins, lipids, and nucleic acids, which determine their heterogeneity and functional properties in cancer progression. Therefore, targeting exosome biogenesis will enhance our understanding of tumorigenesis and also promote the discovery of novel approaches for cancer therapy. In this chapter we summarize the machinery of exosome biogenesis and the local, distant, and systemic effects of exosomes released by cancer cells. Furthermore, we explore how these exosomes regulate the anti-tumor immune response and epigenetic mechanisms to sustain cancer progression and their implications in cancer prevention and treatment.

Blood Microbiota and Its Products: Mechanisms of Interference with Host Cells and Clinical Outcomes

In healthy conditions, blood was considered a sterile environment until the development of new analytical approaches that allowed for the detection of circulating bacterial ribosomal DNA. Currently, debate exists on the origin of the blood microbiota. According to advanced research using dark field microscopy, fluorescent in situ hybridization, flow cytometry, and electron microscopy, so-called microbiota have been detected in the blood. Conversely, others have reported no evidence of a common blood microbiota. Then, it was hypothesized that blood microbiota may derive from distant sites, e.g., the gut or external contamination of blood samples. Alteration of the blood microbiota's equilibrium may lead to dysbiosis and, in certain cases, disease. Cardiovascular, respiratory, hepatic, kidney, neoplastic, and immune diseases have been associated with the presence of Gram-positive and Gram-negative bacteria and/or their products in the blood. For instance, lipopolysaccharides (LPSs) and endotoxins may contribute to tissue damage, fueling chronic inflammation. Blood bacteria can interact with immune cells, especially with monocytes that engulf microorganisms and T lymphocytes via spontaneous binding to their membranes. Moreover, LPSs, extracellular vesicles, and outer membrane vesicles interact with red blood cells and immune cells, reaching distant organs. This review aims to describe the composition of blood microbiota in healthy individuals and those with disease conditions. Furthermore, special emphasis is placed on the interaction of blood microbiota with host cells to better understand disease mechanisms.

Hypothesis: hematogenous metastatic cancer cells of solid tumors may disguise themselves as memory macrophages for metastasis

German pathologist Otto Aichel suggested, a century ago, that the cancer cell acquired its metastatic property from a leukocyte via cell-cell fusion. Since then, several revised versions of this theory have been proposed. Most of the proposals attribute the generation of the metastatic cancer cell to the fusion between a primary cancer cell and a macrophage. However, these theories have not addressed several issues, such as dormancy and stem cell-like self-renewal, of the metastatic cancer cell. On the other hand, recent studies have found that, like T- and B-/plasma cells, macrophages can also be categorized into naïve, effector, and memory/trained macrophages. As a memory/trained macrophage can enter dormancy/quiescence, be awakened from the dormancy/quiescence by acquainted primers, and re-populate via stem cell-like self-renewal, we, therefore, further specify that the macrophage fusing with the cancer cell and contributing to metastasis, belongs with the memory/trained macrophage, not other subtypes of macrophages. The current theory can explain many puzzling clinical features of cancer, including the paradoxal effects (recurrence vs. regression) of microbes on tumors, "spontaneous" and Coley's toxin-induced tumor regression, anticancer activities of β-blockers and anti-inflammatory/anti-immune/antibiotic drugs, oncotaxis, surgery- and trauma-promoted metastasis, and impact of microbiota on tumors. Potential therapeutic strategies, such as Coley's toxin-like preparations, are proposed. This is the last article of our trilogy on carcinogenesis theories.

Breast cancer cell-secreted miR-199b-5p hijacks neurometabolic coupling to promote brain metastasis

Breast cancer metastasis to the brain is a clinical challenge rising in prevalence. However, the underlying mechanisms, especially how cancer cells adapt a distant brain niche to facilitate colonization, remain poorly understood. A unique metabolic feature of the brain is the coupling between neurons and astrocytes through glutamate, glutamine, and lactate. Here we show that extracellular vesicles from breast cancer cells with a high potential to develop brain metastases carry high levels of miR-199b-5p, which shows higher levels in the blood of breast cancer patients with brain metastases comparing to those with metastatic cancer in other organs. miR-199b-5p targets solute carrier transporters (SLC1A2/EAAT2 in astrocytes and SLC38A2/SNAT2 and SLC16A7/MCT2 in neurons) to hijack the neuron-astrocyte metabolic coupling, leading to extracellular retention of these metabolites and promoting cancer cell growth. Our findings reveal a mechanism through which cancer cells of a non-brain origin reprogram neural metabolism to fuel brain metastases.

hTERT-Immortalized Mesenchymal Stem Cell-Derived Extracellular Vesicles: Large-Scale Manufacturing, Cargo Profiling, and Functional Effects in Retinal Epithelial Cells

As the economic burden associated with vision loss and ocular damage continues to rise, there is a need to explore novel treatment strategies. Extracellular vesicles (EVs) are enriched with various biological cargo, and there is abundant literature supporting the reparative and immunomodulatory properties of stem cell EVs across a broad range of pathologies. However, one area that requires further attention is the reparative effects of stem cell EVs in the context of ocular damage. Additionally, most of the literature focuses on EVs isolated from primary stem cells; the use of EVs isolated from human telomerase reverse transcriptase (hTERT)-immortalized stem cells has not been thoroughly examined. Using our large-scale EV-manufacturing platform, we reproducibly manufactured EVs from hTERT-immortalized mesenchymal stem cells (MSCs) and employed various methods to characterize and profile their associated cargo. We also utilized well-established cell-based assays to compare the effects of these EVs on both healthy and damaged retinal pigment epithelial cells. To the best of our knowledge, this is the first study to establish proof of concept for reproducible, large-scale manufacturing of hTERT-immortalized MSC EVs and to investigate their potential reparative properties against damaged retinal cells. The results from our studies confirm that hTERT-immortalized MSC EVs exert reparative effects in vitro that are similar to those observed in primary MSC EVs. Therefore, hTERT-immortalized MSCs may represent a more consistent and reproducible platform than primary MSCs for generating EVs with therapeutic potential.

Extracellular Vesicles for Childhood Cancer Liquid Biopsy

Liquid biopsy involves the utilization of minimally invasive or noninvasive techniques to detect biomarkers in biofluids for disease diagnosis, monitoring, or guiding treatments. This approach is promising for the early diagnosis of childhood cancer, especially for brain tumors, where tissue biopsies are more challenging and cause late detection. Extracellular vesicles offer several characteristics that make them ideal resources for childhood cancer liquid biopsy. Extracellular vesicles are nanosized particles, primarily secreted by all cell types into body fluids such as blood and urine, and contain molecular cargos, i.e., lipids, proteins, and nucleic acids of original cells. Notably, the lipid bilayer-enclosed structure of extracellular vesicles protects their cargos from enzymatic degradation in the extracellular milieu. Proteins and nucleic acids of extracellular vesicles represent genetic alterations and molecular profiles of childhood cancer, thus serving as promising resources for precision medicine in cancer diagnosis, treatment monitoring, and prognosis prediction. This review evaluates the recent progress of extracellular vesicles as a liquid biopsy platform for various types of childhood cancer, discusses the mechanistic roles of molecular cargos in carcinogenesis and metastasis, and provides perspectives on extracellular vesicle-guided therapeutic intervention. Extracellular vesicle-based liquid biopsy for childhood cancer may ultimately contribute to improving patient outcomes.

DNA Content in Embryonic Extracellular Vesicles Is Independent of the Apoptotic Rate in Bovine Embryos Produced In Vitro

Pre-implantation embryos release extracellular vesicles containing different molecules, including DNA. The presence of embryonic DNA in E-EVs released into the culture medium during in vitro embryo production could be useful for genetic diagnosis. However, the vesicles containing DNA might be derived from embryos suffering from apoptosis, i.e., embryos of bad quality. This work intended to confirm that embryos release DNA that is useful for genotyping by evaluating the effect of embryonic apoptosis on DNA content in E-EVs. Bovine embryos were produced by parthenogenesis and in vitro fertilization (IVF). On Day 5, morulae were transferred to individual cultures in an EV-depleted SOF medium. On Day 7, embryos were used to evaluate cellular apoptosis, and each culture medium was collected to evaluate E-EV concentration, characterization, and DNA quantification. While no effect of the origin of the embryo on the apoptotic rate was found, arrested morulae had a higher apoptotic rate. E-EVs containing DNA were identified in all samples, and the concentration of those vesicles was not affected by the origin or quality of the embryos. However, the concentration of DNA was higher in EVs released by the arrested parthenogenetic embryos. There was a correlation between the concentration of E-EVs, the concentration of DNA-positive E-EVs, and the concentration of DNA. There was no negative effect of apoptotic rate on DNA-positive E-EVs and DNA concentration; however, embryos of the best quality with a low apoptotic rate still released EVs containing DNA. This study confirms that the presence of DNA in E-EVs is independent of embryo quality. Therefore, E-EVs could be used in liquid biopsy for noninvasive genetic diagnosis.

Protocol to separate small and large extracellular vesicles from mouse and human cardiac tissues

Extracellular vesicles (EVs) are secreted by cells under various conditions and can contribute to the disease progression in tissues. Here, we present a protocol to separate small and large EVs from mouse hearts and cardiac tissues collected from patients. We describe steps for utilizing enzymatic digestion for release of EVs from interstitial space followed by differential centrifugation and immunoaffinity purification. The isolated EVs can be used for various experiments to gain insight into their in vivo functions. For complete details on the use and execution of this protocol, please refer to Liang et al. (2023).1.

Unlocking the potential of exosomes in cancer research: A paradigm shift in diagnosis, treatment, and prevention

Exosomes, which are tiny particles released by cells, have the ability to transport various molecules, including proteins, lipids, and genetic material containing non-coding RNAs (ncRNAs). They are associated with processes like cancer metastasis, immunity, and tissue repair. Clinical trials have shown exosomes to be effective in treating cancer, inflammation, and chronic diseases. Mesenchymal stem cells (MSCs) and dendritic cells (DCs) are common sources of exosome production. Exosomes have therapeutic potential due to their ability to deliver cargo, modulate the immune system, and promote tissue regeneration. Bioengineered exosomes could revolutionize disease treatment. However, more research is needed to understand exosomes in tumor growth and develop new therapies. This paper provides an overview of exosome research, focusing on cancer and exosome-based therapies including chemotherapy, radiotherapy, and vaccines. It explores exosomes as a drug delivery system for cancer therapy, highlighting their advantages. The article discusses using exosomes for various therapeutic agents, including drugs, antigens, and RNAs. It also examines challenges with engineered exosomes. Analyzing exosomes for clinical purposes faces limitations in sensitivity, specificity, and purification. On the other hand, Nanotechnology offers solutions to overcome these challenges and unlock exosome potential in healthcare. Overall, the article emphasizes the potential of exosomes for personalized and targeted cancer therapy, while acknowledging the need for further research.

The Proteome of Extracellular Vesicles Released from Pulmonary Microvascular Endothelium Reveals Impact of Oxygen Conditions on Biotrauma

The lung can experience different oxygen concentrations, low as in hypoxia, high as under supplemental oxygen therapy, or oscillating during intermittent hypoxia as in obstructive sleep apnea or intermittent hypoxia/hyperoxia due to cyclic atelectasis in the ventilated patient. This study aimed to characterize the oxygen-condition-specific protein composition of extracellular vesicles (EVs) released from human pulmonary microvascular endothelial cells in vitro to decipher their potential role in biotrauma using quantitative proteomics with bioinformatic evaluation, transmission electron microscopy, flow cytometry, and non-activated thromboelastometry (NATEM). The release of vesicles enriched in markers CD9/CD63/CD81 was enhanced under intermittent hypoxia, strong hyperoxia and intermittent hypoxia/hyperoxia. Particles with exposed phosphatidylserine were increased under intermittent hypoxia. A small portion of vesicles were tissue factor-positive, which was enhanced under intermittent hypoxia and intermittent hypoxia/hyperoxia. EVs from treatment with intermittent hypoxia induced a significant reduction of Clotting Time in NATEM analysis compared to EVs isolated after normoxic exposure, while after intermittent hypoxia/hyperoxia, tissue factor in EVs seems to be inactive. Gene set enrichment analysis of differentially expressed genes revealed that EVs from individual oxygen conditions potentially induce different biological processes such as an inflammatory response under strong hyperoxia and intermittent hypoxia/hyperoxia and enhancement of tumor invasiveness under intermittent hypoxia.

Lung Fibroblasts Take up Breast Cancer Cell-derived Extracellular Vesicles Partially Through MEK2-dependent Macropinocytosis

Extracellular vesicles (EV) have emerged as critical effectors in the cross-talk between cancer and normal cells by transferring intracellular materials between adjacent or distant cells. Previous studies have begun to elucidate how cancer cells, by secreting EVs, adapt normal cells at a metastatic site to facilitate cancer cell metastasis. In this study, we utilized a high-content microscopic screening platform to investigate the mechanisms of EV uptake by primary lung fibroblasts. A selected library containing 90 FDA-approved anticancer drugs was screened for the effect on fibroblast uptake of EVs from MDA-MB-231 breast cancer cells. Among the drugs identified to inhibit EV uptake without exerting significant cytotoxicity, we validated the dose-dependent effect of Trametinib (a MEK1/2 inhibitor) and Copanlisib (a PI3K inhibitor). Trametinib suppressed macropinocytosis in lung fibroblasts and inhibited EV uptake with a higher potency comparing with Copanlisib. Gene knockdown and overexpression studies demonstrated that uptake of MDA-MB-231 EVs by lung fibroblasts required MEK2. These findings provide important insights into the mechanisms underlying lung fibroblast uptake of breast cancer cell-derived EVs, which could play a role in breast cancer metastasis to the lungs and suggest potential therapeutic targets for preventing or treating this deadly disease.

SIGNIFICANCE

Through a phenotypic screen, we found that MEK inhibitor Trametinib suppressed EV uptake and macropinocytosis in lung fibroblasts, and that EV uptake is mediated by MEK2 in these cells. Our results suggest that MEK2 inhibition could serve as a strategy to block cancer EV uptake by lung fibroblasts.

Extracellular RNA in oncogenesis, metastasis and drug resistance

Extracellular vesicles and nanoparticles (EVPs) are now recognized as a novel form of cell-cell communication. All cells release a wide array of heterogeneous EVPs with distinct protein, lipid, and RNA content, dependent on the pathophysiological state of the donor cell. The overall cargo content in EVPs is not equivalent to cellular levels, implying a regulated pathway for selection and export. In cancer, release and uptake of EVPs within the tumour microenvironment can influence growth, proliferation, invasiveness, and immune evasion. Secreted EVPs can also have distant, systemic effects that can promote metastasis. Here, we review current knowledge of EVP biogenesis and cargo selection with a focus on the role that extracellular RNA plays in oncogenesis and metastasis. Almost all subtypes of RNA have been identified in EVPs, with miRNAs being the best characterized. We review the roles of specific miRNAs that have been detected in EVPs and that play a role in oncogenesis and metastasis.

Air Pollution and Lung Cancer: Contributions of Extracellular Vesicles as Pathogenic Mechanisms and Clinical Utility

PURPOSE OF REVIEW

This review addresses the pressing issue of air pollution's threat to human health, focusing on its connection to non-small cell lung cancer (NSCLC) development. The aim is to explore the role of extracellular vesicles (EVs) as potential pathogenic mechanisms in lung cancer, including NSCLC, induced by air pollutants.

RECENT FINDINGS

Recent research highlights EVs as vital mediators of intercellular communication and key contributors to cancer progression. Notably, this review emphasizes the cargo of EVs released by both cancerous and non-cancerous lung cells, shedding light on their potential role in promoting various aspects of tumor development. The review underscores the importance of comprehending the intricate interplay between air pollution, biological damage mechanisms, and EV-mediated communication during NSCLC development. Major takeaways emphasize the significance of this understanding in addressing air pollution-related lung cancer. Future research avenues are also highlighted, aiming to enhance the applicability of EVs for diagnosis and targeted therapies, ultimately mitigating the inevitable impact of air pollution on NSCLC development and treatment.

Extracellular Vesicle Heterogeneity and Its Impact for Regenerative Medicine Applications

Extracellular vesicles (EVs) are cell-derived membrane-enclosed particles that are involved in physiologic and pathologic processes. EVs are increasingly being studied for therapeutic applications in the field of regenerative medicine. Therapeutic application of stem cell-derived EVs has shown great potential to stimulate tissue repair. However, the exact mechanisms through which they induce this effect have not been fully clarified. This may to a large extent be attributed to a lack of knowledge on EV heterogeneity. Recent studies suggest that EVs represent a heterogeneous population of vesicles with distinct functions. The heterogeneity of EVs can be attributed to differences in their biogenesis, and as such, they can be classified into distinct populations that can then be further subcategorized into various subpopulations. A better understanding of EV heterogeneity is crucial for elucidating their mechanisms of action in tissue regeneration. This review provides an overview of the latest insights on EV heterogeneity related to tissue repair, including the different characteristics that contribute to such heterogeneity and the functional differences among EV subtypes. It also sheds light on the challenges that hinder clinical translation of EVs. Additionally, innovative EV isolation techniques for studying EV heterogeneity are discussed. Improved knowledge of active EV subtypes would promote the development of tailored EV therapies and aid researchers in the translation of EV-based therapeutics to the clinic. SIGNIFICANCE STATEMENT: Within this review we discuss the differences in regenerative properties of extracellular vesicle (EV) subpopulations and implications of EV heterogeneity for development of EV-based therapeutics. We aim to provide new insights into which aspects are leading to heterogeneity in EV preparations and stress the importance of EV heterogeneity studies for clinical applications.

Spheresomes are the main extracellular vesicles in low-grade gliomas

Cancer progression and its impact on treatment response and prognosis is deeply regulated by tumour microenvironment (TME). Cancer cells are in constant communication and modulate TME through several mechanisms, including transfer of tumour-promoting cargos through extracellular vesicles (EVs) or oncogenic signal detection by primary cilia. Spheresomes are a specific EV that arise from rough endoplasmic reticulum-Golgi vesicles. They accumulate beneath cell membrane and are released to the extracellular medium through multivesicular spheres. This study describes spheresomes in low-grade gliomas using electron microscopy. We found that spheresomes are more frequent than exosomes in these tumours and can cross the blood-brain barrier. Moreover, the distinct biogenesis processes of these EVs result in unique cargo profiles, suggesting different functional roles. We also identified primary cilia in these tumours. These findings collectively contribute to our understanding of glioma progression and metastasis.

Ectopic ATP synthase stimulates the secretion of extracellular vesicles in cancer cells

ABSTARCT

Ectopic ATP synthase on the plasma membrane (eATP synthase) has been found in various cancer types and is a potential target for cancer therapy. However, whether it provides a functional role in tumor progression remains unclear. Here, quantitative proteomics reveals that cancer cells under starvation stress express higher eATP synthase and enhance the production of extracellular vesicles (EVs), which are vital regulators within the tumor microenvironment. Further results show that eATP synthase generates extracellular ATP to stimulate EV secretion by enhancing P2X7 receptor-triggered Ca2+ influx. Surprisingly, eATP synthase is also located on the surface of tumor-secreted EVs. The EVs-surface eATP synthase increases the uptake of tumor-secreted EVs in Jurkat T-cells via association with Fyn, a plasma membrane protein found in immune cells. The eATP synthase-coated EVs uptake subsequently represses the proliferation and cytokine secretion of Jurkat T-cells. This study clarifies the role of eATP synthase on EV secretion and its influence on immune cells.

Metastatic Dissemination: Role of Tumor-Derived Extracellular Vesicles and Their Use as Clinical Biomarkers

Cancer is a major cause of mortality in humans; often, rather than the primary tumor, it is the presence of metastases that are the cause of death. Extracellular vesicles (EVs) are small structures released by both normal and cancer cells; regarding the latter, they have been demonstrated to modulate almost all cancer-related processes, such as invasion, angiogenesis induction, drug resistance, and immune evasion. In the last years, it has become clear how EVs are widely involved in metastatic dissemination as well as in pre-metastatic niche (PMN) formation. Indeed, in order to achieve a successful metastatic process, i.e., penetration by cancer cells into distant tissues, the shaping of a favorable environment into those distant tissue, i.e., PMN formation, is mandatory. This process consists of an alteration that takes place in a distant organ and paves the way for the engraftment and growth of circulating tumor cells derived from the tumor primary site. This review focuses on the role of EVs in pre-metastatic niche formation and metastatic dissemination, also reporting the last studies suggesting the EVs role as biomarkers of metastatic diseases, possibly in a liquid biopsy approach.

Comparative Proteomics Analysis of Exosomes Identifies Key Pathways and Protein Markers Related to Breast Cancer Metastasis

Proteomics analysis of circulating exosomes derived from cancer cells represents a promising approach to the elucidation of cell-cell communication and the discovery of putative biomarker candidates for cancer diagnosis and treatment. Nonetheless, the proteome of exosomes derived from cell lines with different metastatic capabilities still warrants further investigation. Here, we present a comprehensive quantitative proteomics investigation of exosomes isolated from immortalized mammary epithelial cells and matched tumor lines with different metastatic potentials in an attempt to discover exosome markers specific to breast cancer (BC) metastasis. A total of 2135 unique proteins were quantified with a high confidence level from 20 isolated exosome samples, including 94 of the TOP 100 exosome markers archived by ExoCarta. Moreover, 348 altered proteins were observed, among which several metastasis-specific markers, including cathepsin W (CATW), magnesium transporter MRS2 (MRS2), syntenin-2 (SDCB2), reticulon-4 (RTN), and UV excision repair protein RAD23 homolog (RAD23B), were also identified. Notably, the abundance of these metastasis-specific markers corresponds well with the overall survival of BC patients in clinical settings. Together, these data provide a valuable dataset for BC exosome proteomics investigation and prominently facilitate the elucidation of the molecular mechanisms underlying primary tumor development and progression.

Proteins Found in the Triple-Negative Breast Cancer Secretome and Their Therapeutic Potential

The cancer secretome comprises factors secreted by tumors, including cytokines, growth factors, proteins from the extracellular matrix (ECM), proteases and protease inhibitors, membrane and extracellular vesicle proteins, peptide hormones, and metabolic proteins. Secreted proteins provide an avenue for communication with other tumor cells and stromal cells, and these in turn promote tumor growth and progression. Breast cancer is the most commonly diagnosed cancer in women in the US and worldwide. Triple-negative breast cancer (TNBC) is characterized by its aggressiveness and its lack of expression of the estrogen receptor (ER), progesterone receptor (PR), and HER2, making it unable to be treated with therapies targeting these protein markers, and leaving patients to rely on standard chemotherapy. In order to develop more effective therapies against TNBC, researchers are searching for targetable molecules specific to TNBC. Proteins in the TNBC secretome are involved in wide-ranging cancer-promoting processes, including tumor growth, angiogenesis, inflammation, the EMT, drug resistance, invasion, and development of the premetastatic niche. In this review, we catalog the currently known proteins in the secretome of TNBC tumors and correlate these secreted molecules with potential therapeutic opportunities to facilitate translational research.

The Biological Effect of Small Extracellular Vesicles on Colorectal Cancer Metastasis

Colorectal cancer (CRC) is a malignancy that seriously threatens human health, and metastasis from CRC is a major cause of death and poor prognosis for patients. Studying the potential mechanisms of small extracellular vesicles (sEVs) in tumor development may provide new options for early and effective diagnosis and treatment of CRC metastasis. In this review, we systematically describe how sEVs mediate epithelial mesenchymal transition (EMT), reconfigure the tumor microenvironment (TME), modulate the immune system, and alter vascular permeability and angiogenesis to promote CRC metastasis. We also discuss the current difficulties in studying sEVs and propose new ideas.

Extracellular vesicles in cancer therapy

Extracellular vesicles (EVs), including a variety of membrane-enclosed nanosized particles carrying cell-derived cargo, mediate a major type of intercellular communication in physiological and pathological processes. Both cancer and non-cancer cells secrete EVs, which can travel to and influence various types of cells at the primary tumor site as well as in distant organs. Tumor-derived EVs contribute to cancer cell plasticity and resistance to therapy, adaptation of tumor microenvironment, local and systemic vascular remodeling, immunomodulation, and establishment of pre-metastatic niches. Therefore, targeting the production, uptake, and function of tumor-derived EVs has emerged as a new strategy for stand-alone or combinational therapy of cancer. On the other hand, as EV cargo partially reflects the genetic makeup and phenotypic properties of the secreting cell, EV-based biomarkers that can be detected in biofluids are being developed for cancer diagnosis and for predicting and monitoring tumor response to therapy. Meanwhile, EVs from presumably safe sources are being developed as delivery vehicles for anticancer therapeutic agents and as anticancer vaccines. Numerous reviews have discussed the biogenesis and characteristics of EVs and their functions in cancer. Here, I highlight recent advancements in translation of EV research outcome towards improved care of cancer, including developments of non-invasive EV-based biomarkers and therapeutic agents targeting tumor-derived EVs as well as engineering of therapeutic EVs.

Cancer Three-Dimensional Spheroids Mimic In Vivo Tumor Features, Displaying “Inner” Extracellular Vesicles and Vasculogenic Mimicry

The role of extracellular vesicles (EVs) as mediators of cell-to-cell communication in cancer progression is widely recognized. In vitro studies are routinely performed on 2D culture models, but recent studies suggest that 3D cultures could represent a more valid model. Human ovarian cancer cells CABA I were cultured by the hanging drop method to form tumor spheroids, that were moved to low adhesion supports to observe their morphology by Scanning Electron Microscopy (SEM) and to isolate the EVs. EVs release was verified by SEM and their identity confirmed by morphology (Transmission Electron Microscopy, TEM), size distribution (Nanoparticles Tracking Analysis), and markers (CD63, CD9, TSG-101, Calnexin). CABA I form spheroids with a clinically relevant size, above 400 μm; they release EVs on their external surface and also trap “inner” EVs. They also produce vasculogenic mimicry-like tubules, that bulge from the spheroid and are composed of a hollow lumen delimited by tumor cells. CABA I can be grown as multicellular spheroids to easily isolate EVs. The presence of features typical of in vivo tumors (inner entrapped EVs and vasculogenic mimicry) suggests their use as faithful experimental models to screen therapeutic drugs targeting these pro-tumorigenic processes.

Cancer-cell-secreted extracellular vesicles suppress insulin secretion through miR-122 to impair systemic glucose homeostasis and contribute to tumour growth

Epidemiological studies demonstrate an association between breast cancer (BC) and systemic dysregulation of glucose metabolism. However, how BC influences glucose homeostasis remains unknown. We show that BC-derived extracellular vesicles (EVs) suppress pancreatic insulin secretion to impair glucose homeostasis. EV-encapsulated miR-122 targets PKM in β-cells to suppress glycolysis and ATP-dependent insulin exocytosis. Mice receiving high-miR-122 EVs or bearing BC tumours exhibit suppressed insulin secretion, enhanced endogenous glucose production, impaired glucose tolerance and fasting hyperglycaemia. These effects contribute to tumour growth and are abolished by inhibiting EV secretion or miR-122, restoring PKM in β-cells or supplementing insulin. Compared with non-cancer controls, patients with BC have higher levels of circulating EV-encapsulated miR-122 and fasting glucose concentrations but lower fasting insulin; miR-122 levels are positively associated with glucose and negatively associated with insulin. Therefore, EV-mediated impairment of whole-body glycaemic control may contribute to tumour progression and incidence of type 2 diabetes in some patients with BC.

An emerging role of KRAS in biogenesis, cargo sorting and uptake of cancer-derived extracellular vesicles

Extracellular vesicles (EVs) are nanovesicles secreted for intercellular communication with endosomal network regulating secretion of small EVs (or exosomes) that play roles in cancer progression. As an essential oncoprotein, Kirsten rat sarcoma virus (KRAS) is tightly regulated by its endosomal trafficking for membrane attachment. However, the crosstalk between KRAS and EVs has been scarcely discussed despite its endocytic association. An overview of the oncogenic role of KRAS focusing on its correlation with cancer-associated EVs should provide important clues for disease prognosis and inspire novel therapeutic approaches for treating KRAS mutant cancers. Therefore, this review summarizes the relevant studies that provide substantial evidence linking KRAS mutation to EVs and discusses the oncogenic implication from the aspects of biogenesis, cargo sorting, and release and uptake of the EVs.

Cancer-cell-secreted miR-122 suppresses O-GlcNAcylation to promote skeletal muscle proteolysis

A decline in skeletal muscle mass and low muscular strength are prognostic factors in advanced human cancers. Here we found that breast cancer suppressed O-linked N-acetylglucosamine (O-GlcNAc) protein modification in muscle through extracellular-vesicle-encapsulated miR-122, which targets O-GlcNAc transferase (OGT). Mechanistically, O-GlcNAcylation of ryanodine receptor 1 (RYR1) competed with NEK10-mediated phosphorylation and increased K48-linked ubiquitination and proteasomal degradation; the miR-122-mediated decrease in OGT resulted in increased RYR1 abundance. We further found that muscular protein O-GlcNAcylation was regulated by hypoxia and lactate through HIF1A-dependent OGT promoter activation and was elevated after exercise. Suppressed O-GlcNAcylation in the setting of cancer, through increasing RYR1, led to higher cytosolic Ca2+ and calpain protease activation, which triggered cleavage of desmin filaments and myofibrillar destruction. This was associated with reduced skeletal muscle mass and contractility in tumour-bearing mice. Our findings link O-GlcNAcylation to muscular protein homoeostasis and contractility and reveal a mechanism of cancer-associated muscle dysregulation.

Nanomaterial Exposure, Extracellular Vesicle Biogenesis and Adverse Cellular Outcomes: A Scoping Review

The progressively increasing use of nanomaterials (NMs) has awakened issues related to nanosafety and its potential toxic effects on human health. Emerging studies suggest that NMs alter cell communication by reshaping and altering the secretion of extracellular vesicles (EVs), leading to dysfunction in recipient cells. However, there is limited understanding of how the physicochemical characteristics of NMs alter the EV content and their consequent physiological functions. Therefore, this review explored the relevance of EVs in the nanotoxicology field. The current state of the art on how EVs are modulated by NM exposure and the possible regulation and modulation of signaling pathways and physiological responses were assessed in detail. This review followed the manual for reviewers produced by The Joanna Brigs Institute for Scoping Reviews and the PRISMA extension for Scoping Reviews (PRISMA-ScR): checklist and explanation. The research question, "Do NMs modulate cellular responses mediated by EVs?" was analyzed following the PECO model (P (Population) = EVs, E (Exposure) = NMs, C (Comparator) = EVs without exposure to NMs, O (Outcome) = Cellular responses/change in EVs) to help methodologically assess the association between exposure and outcome. For each theme in the PECO acronym, keywords were defined, organized, and researched in PubMed, Science Direct, Scopus, Web of Science, EMBASE, and Cochrane databases, up to 30 September 2021. In vitro, in vivo, ex vivo, and clinical studies that analyzed the effect of NMs on EV biogenesis, cargo, and cellular responses were included in the analysis. The methodological quality assessment was conducted using the ToxRTool, ARRIVE guideline, Newcastle Ottawa and the EV-TRACK platform. The search in the referred databases identified 2944 articles. After applying the eligibility criteria and two-step screening, 18 articles were included in the final review. We observed that depending on the concentration and physicochemical characteristics, specific NMs promote a significant increase in EV secretion as well as changes in their cargo, especially regarding the expression of proteins and miRNAs, which, in turn, were involved in biological processes that included cell communication, angiogenesis, and activation of the immune response, etc. Although further studies are necessary, this work suggests that molecular investigations on EVs induced by NM exposure may become a potential tool for toxicological studies since they are widely accessible biomarkers that may form a bridge between NM exposure and the cellular response and pathological outcome.

Secreted Non-Coding RNAs: Functional Impact on the Tumor Microenvironment and Clinical Relevance in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subtype of breast carcinoma characterized by poor prognosis and high rate of metastasis. Current treatment is based on chemo- and/or radiotherapy and surgery. TNBC is devoid of estrogen, progesterone and HER2 receptors. Although precision medicine has come a long way to ameliorate breast cancer disease management, targeted therapies for the treatment of TNBC patients are still limited. Mounting evidence has shown that non-coding RNAs (ncRNAs) drive many oncogenic processes at the basis of increased proliferation, invasion and angiogenesis in TNBC, strongly contributing to tumor progression and resistance to treatments. Many of these ncRNAs are secreted in the tumor microenvironment (TME) and impinge on the activity of the diverse immune and stromal cell types infiltrating the TME. Importantly, secreted ncRNAs may be detected as circulating molecules in serum/plasma from cancer patients and are emerging a promising diagnostic/therapeutic tools in TNBC. This review aims to discuss novel insights about the role of secreted circulating ncRNAs in the intercellular communication in the tumor microenvironment and their potential clinical use as diagnostic and prognostic non-invasive biomarkers in TNBC.

Extracellular vesicle research in reproductive science- Paving the way for clinical achievements

Mammalian conception involves a multitude of reciprocal interactions via a molecular dialogue between mother and conceptus. Extracellular vesicles (EVs) are secreted membrane-encapsulated particles that mediate cell-to-cell communication in various contexts. EVs, which are present in seminal, follicular, oviductal, and endometrial fluids, as well as in embryo secretions, carry molecular constituents that impact gamete maturation, fertilization, early embryo development, and embryo-maternal communication. The distribution, concentration, and molecular cargo of EVs are regulated by steroid hormones and the health status of the tissue of origin, and thus are influenced by menstrual phase, stage of conception, and the presence of infertility-associated diseases. EVs have been recognized as a novel source of biomarkers and potential reproductive medicine therapeutics, particularly for assisted reproductive technology (ART). There are still many technological and scientific hindrances to be overcome before EVs can be used in clinical diagnostic and therapeutic ART applications. Issues to be resolved include the lack of standardized measurement protocols and an absence of absolute EV quantification technologies. Additionally, clinically suitable and robust EV isolation methods have yet to be developed. In this review, we provide an overview of EV-mediated interactions during the early stages of reproduction from gamete maturation to embryo implantation and then outline the technological progress that must be made for EV applications to be translated to clinical settings.

Extracellular vesicles in urological malignancies

Extracellular vesicles (EVs) are small lipid bound structures released from cells containing bioactive cargoes. Both the type of cargo and amount loaded varies compared to that of the parent cell. The characterisation of EVs in cancers of the male urogenital tract has identified several cargoes with promising diagnostic and disease monitoring potential. EVs released by cancers of the male urogenital tract promote cell-to-cell communication, migration, cancer progression and manipulate the immune system promoting metastasis by evading the immune response. Their use as diagnostic biomarkers represents a new area of screening and disease detection, potentially reducing the need for invasive biopsies. Many validated EV cargoes have been found to have superior sensitivity and specificity than current diagnostic tools currently in use. The use of EVs to improve disease monitoring and develop novel therapeutics will enable clinicians to individualise patient management in the exciting era of personalised medicine.

Intelligent Probabilistic System for Digital Tracing Cellular Origin of Individual Clinical Extracellular Vesicles

Extracellular vesicles (EVs) are small vesicles secreted by various cell types to mediate cell-to-cell communication through the transfer of macromolecules. EVs carry multiple cargo molecules that reflect the origins of their donor cells; thus, they can be considered reliable biomarkers for early cancer diagnosis. However, the diverse cellular origin of EV masks the detection signals generated by both tumor- and nontumor-derived cells. Thereby, the capability to recognize the cellular origin of EVs is the prerequisite for their diagnostic applications. In the present study, we develop an intelligent probabilistic system for tracing the cellular origin of individual EVs using single-molecule multicolor imaging. Through the analysis of the expression profile of two typical membrane protein markers, CD9 and CD63, on single EVs, accurate and rapid probabilistic recognition of EVs derived from individual tumor and nontumor cells in clinical samples is achieved. The correlation between cellular origin and surface protein phenotyping on single EVs is also exemplified. The proposed system holds great potential for advancing EVs as reliable clinical indicators and exploring their biological functions.

Molecular subversion of Cdc42 signalling in cancer

Cdc42 is a member of the Rho family of small GTPases and a master regulator of the actin cytoskeleton, controlling cell motility, polarity and cell cycle progression. This small G protein and its regulators have been the subject of many years of fruitful investigation and the advent of functional genomics and proteomics has opened up new avenues of exploration including how it functions at specific locations in the cell. This has coincided with the introduction of new structural techniques with the ability to study small GTPases in the context of the membrane. The role of Cdc42 in cancer is well established but the molecular details of its action are still being uncovered. Here we review alterations found to Cdc42 itself and to key components of the signal transduction pathways it controls in cancer. Given the challenges encountered with targeting small G proteins directly therapeutically, it is arguably the regulators of Cdc42 and the effector signalling pathways downstream of the small G protein which will be the most tractable targets for therapeutic intervention. These will require interrogation in order to fully understand the global signalling contribution of Cdc42, unlock the potential for mapping new signalling axes and ultimately produce inhibitors of Cdc42 driven signalling.

Exosomes in Breast Cancer - Mechanisms of Action and Clinical Potential

Extracellular vesicles (EV) are a heterogeneous group of cell-derived membrane vesicles comprising apoptotic bodies, microvesicles, and small EVs also called as exosomes. Exosomes when initially identified were considered as a waste product but the advancement in research techniques have provided insight into the important roles of exosomes in cell-cell communication, various biological processes and diseases, including cancer. As an important component of EVs, exosomes contain various biomolecules such as miRNAs, lipids, and proteins that largely reflect the characteristics of their parent cells. Notably, cancer cells generate and secrete many more exosomes than normal cells. A growing body of evidence suggests that exosomes, as mediators of intercellular cross-talk, play a role in tumorigenesis, cancer cell invasion, angiogenesis, tumor microenvironment (TME) formation, and cancer metastasis. As we gain more insights into the association between exosomes and cancer, the potential of exosomes for clinical use is becoming more intriguing. This review is focused on the role of exosomes in breast cancer, in terms of breast cancer biology, mechanism of action, potential as biomarkers, and therapeutic opportunities.

Emerging Role of Exosomes in Liquid Biopsy for Monitoring Prostate Cancer Invasion and Metastasis

Prostate cancer (PCa) is the most common solid tumor in men. While patients with local PCa have better prognostic survival, patients with metastatic PCa have relatively high mortality rates. Existing diagnostic methods for PCa rely on tissue biopsy and blood prostate-specific antigen (PSA) detection; however, the PSA test does not detect aggressive PCa. Liquid biopsy is a promising technique to overcome tumor heterogeneity in diagnosis, provide more comprehensive information, and track tumor progression over time, allowing for the development of treatment options at all stages of PCa. Exosomes containing proteins and nucleic acids are potential sources of tumor biomarkers. Accumulating evidence indicates that exosomes play important roles in cell communication and tumor progression and are suitable for monitoring PCa progression and metastasis. In this review, we summarize recent advances in the use of exosomal proteins and miRNAs as biomarkers for monitoring PCa invasion and metastasis and discuss their feasibility in clinical diagnosis.

Extracellular Vesicles as Promising Carriers in Drug Delivery: Considerations from a Cell Biologist's Perspective

The use of extracellular vesicles as cell-free therapy is a promising approach currently investigated in several disease models. The intrinsic capacity of extracellular vesicles to encapsulate macromolecules within their lipid bilayer membrane-bound lumen is a characteristic exploited in drug delivery to transport active pharmaceutical ingredients. Besides their role as biological nanocarriers, extracellular vesicles have a specific tropism towards target cells, which is a key aspect in precision medicine. However, the little knowledge of the mechanisms governing the release of a cargo macromolecule in recipient cells and the Good Manufacturing Practice (GMP) grade scale-up manufacturing of extracellular vesicles are currently slowing their application as drug delivery nanocarriers. In this review, we summarize, from a cell biologist's perspective, the main evidence supporting the role of extracellular vesicles as promising carriers in drug delivery, and we report five key considerations that merit further investigation before translating Extracellular Vesicles (EVs) to clinical applications.

Diagnostic and Therapeutic Potential of Extracellular Vesicles in B-Cell Malignancies

Extracellular vesicles (EV), comprising microvesicles and exosomes, are particles released by every cell of an organism, found in all biological fluids, and commonly involved in cell-to-cell communication through the transfer of cargo materials such as miRNA, proteins, and immune-related ligands (e.g., FasL and PD-L1). An important characteristic of EV is that their composition, abundance, and roles are tightly related to the parental cells. This translates into a higher release of characteristic pro-tumor EV by cancer cells that leads to harming signals toward healthy microenvironment cells. In line with this, the key role of tumor-derived EV in cancer progression was demonstrated in multiple studies and is considered a hot topic in the field of oncology. Given their characteristics, tumor-derived EV carry important information concerning the state of tumor cells. This can be used to follow the outset, development, and progression of the neoplasia and to evaluate the design of appropriate therapeutic strategies. In keeping with this, the present brief review will focus on B-cell malignancies and how EV can be used as potential biomarkers to follow disease progression and stage. Furthermore, we will explore several proposed strategies aimed at using biologically engineered EV for treatment (e.g., drug delivery mechanisms) as well as for impairing the biogenesis, release, and internalization of cancer-derived EV, with the final objective to disrupt tumor–microenvironment communication.

Multiple Myeloma-Derived Extracellular Vesicles Induce Osteoclastogenesis through the Activation of the XBP1/IRE1α Axis

Bone disease severely affects the quality of life of over 70% of multiple myeloma (MM) patients, which daily experience pain, pathological fractures, mobility issues and an increased mortality. Recent data have highlighted the crucial role of the endoplasmic reticulum-associated unfolded protein response (UPR) in malignant transformation and tumor progression; therefore, targeting of UPR-related molecules may open novel therapeutic avenues. Endoplasmic reticulum (ER) stress and UPR pathways are constitutively activated in MM cells, which are characterized by an increased protein turnover as a consequence of high production of immunoglobulins and high rates of protein synthesis. A great deal of scientific data also evidenced that a mild activation of UPR pathway can regulate cellular differentiation. Our previous studies revealed that MM cell-derived small extracellular vesicle (MM-EV) modulated osteoclasts (OCs) function and induced OCs differentiation. Here, we investigated the role of the UPR pathway, and in particular of the IRE1α/XBP1 axis, in osteoclastogenesis induced by MM-EVs. By proteomic analysis, we identified UPR signaling molecules as novel MM-EV cargo, prompting us to evaluate the effects of the MM-EVs on osteoclastogenesis through UPR pathway. MM-EVs administration in a murine macrophage cell line rapidly induced activation of IRE1α by phosphorylation in S724; accordingly, Xbp1 mRNA splicing was increased and the transcription of NFATc1, a master transcription factor for OCs differentiation, was activated. Some of these results were also validated using both human primary OC cultures and MM-EVs from MM patients. Notably, a chemical inhibitor of IRE1α (GSK2850163) counteracted MM-EV-triggered OC differentiation, hampering the terminal stages of OCs differentiation and reducing bone resorption.