Directional cell movement through tissues is controlled by exosome secretion

Pulp-Derived Exosomes in a Fibrin-Based Regenerative Root Filling Material

Regenerative endodontics has been described as a paradigm shift in dentistry, despite its current limitation to immature teeth and reparative rather than regenerative outcomes. Cell-free treatments are favored because of regulatory issues. However, the recruitment of host-derived stem cells to the desired site remains challenging. We investigated whether dental pulp-derived exosomes, which are extracellular vesicles that contain proteins, lipids, RNA, and DNA and thus mirror their parental cells, may be used for this purpose. The use of exosomes may present appreciable advantages over the direct use of transplanted stem cells due to a higher safety profile, easier isolation, preservation, and handling. Here we harvested exosomes from a cultured third-molar pulp cell and assessed them by transmission electron microscopy and Western blotting. Human mesenchymal stem cells (MSCs) were exposed to these exosomes to assess exosome uptake, cell migration, and proliferation. In addition, a fibrin gel (i.e., a diluted fibrin sealant), was assessed as a delivery system for the exosomes. Our results show that exosomes attracted MSCs, and the fibrin gel enhanced their effect. Moreover, exosomes improved the proliferation of MSCs. Therefore, we propose that pulp-derived exosomes in combination with a fibrin gel could be a powerful combination for clinical translation towards improved cell-free regenerative endodontics and thus represent a new way to fill dental hard tissues.

Tumor cell-derived exosomes home to their cells of origin and can be used as Trojan horses to deliver cancer drugs

Cancer is the second leading cause of death worldwide and patients are in urgent need of therapies that can effectively target cancer with minimal off-target side effects. Exosomes are extracellular nano-shuttles that facilitate intercellular communication between cells and organs. It has been established that tumor-derived exosomes contain a similar protein and lipid composition to that of the cells that secrete them, indicating that exosomes might be uniquely employed as carriers for anti-cancer therapeutics. Methods: We isolated exosomes from two cancer cell lines, then co-cultured each type of cancer cells with these two kinds of exosomes and quantified exosome. HT1080 or Hela exosomes were systemically injected to Nude mice bearing a subcutaneous HT1080 tumor to investigate their cancer-homing behavior. Moreover, cancer cell-derived exosomes were engineered to carry Doxil (a common chemotherapy drug), known as D-exo, were used to detect their target and therapeutic efficacy as anti-cancer drugs. Exosome proteome array analysis were used to reveal the mechanism underly this phenomenon. Results: Exosomes derived from cancer cells fuse preferentially with their parent cancer cells, in vitro. Systemically injected tumor-derived exosomes home to their original tumor tissues. Moreover, compared to Doxil alone, the drug-loaded exosomes showed enhanced therapeutic retention in tumor tissues and eradicated them more effectively in nude mice. Exosome proteome array analysis revealed distinct integrin expression patterns, which might shed light on the underlying mechanisms that explain the exosomal cancer-homing behavior. Conclusion: Here we demonstrate that the exosomes' ability to target the parent cancer is a phenomenon that opens up new ways to devise targeted therapies to deliver anti-tumor drugs.

Extracellular Vesicles Mediate Neuroprotection and Functional Recovery after Traumatic Brain Injury

The lack of effective therapies for moderate-to-severe traumatic brain injuries (TBIs) leaves patients with lifelong disabilities. Neural stem cells (NSCs) have demonstrated great promise for neural repair and regeneration. However, direct evidence to support their use as a cell replacement therapy for neural injuries is currently lacking. We hypothesized that NSC-derived extracellular vesicles (NSC EVs) mediate repair indirectly after TBI by enhancing neuroprotection and therapeutic efficacy of endogenous NSCs. We evaluated the short-term effects of acute intravenous injections of NSC EVs immediately following a rat TBI. Male NSC EV-treated rats demonstrated significantly reduced lesion sizes, enhanced presence of endogenous NSCs, and attenuated motor function impairments 4 weeks post-TBI, when compared with vehicle- and TBI-only male controls. Although statistically not significant, we observed a therapeutic effect of NSC EVs on brain lesion volume, nestin expression, and behavioral recovery in female subjects. Our study demonstrates the neuroprotective and functional benefits of NSC EVs for treating TBI and points to gender-dependent effects on treatment outcomes, which requires further investigation.

Inhibition of kras-derived exosomes downregulates immunosuppressive BACH2/GATA-3 expression via RIP-3 dependent necroptosis and miR-146/miR-210 modulation

Immunosuppressive chemoresistance is a major challenge in lung cancer treatment. Exosomes present in the tumor microenviroment are implicated in chemoresistant-related immune suppression, and metastasis but the exact pathogenic role of lung-derived exosomes is still uncertain. Recent reports reveal that lung cancer pathogenesis is strictly associated with a exosomal tumor supportive status and a dysfunctional immune system. In this study, we investigate the role of Kras-derived exosomes in chemoresistant immunosuppression in which neoplastic cells create a metabolic-sustained microenvironment. Findings reveal that Kras-derived exosomes induce regulation of SMARCE1/NCOR1 chromatin remodeling genes promoting pre-metastatic niche formation in naive mice and consequently increase lung metastatic burden. Furthermore, exosomal Kras inhibition downregulated transcription factor BACH2/GATA-3 expression in lung tumor tissues by shifting pyruvate/PKM2 dependent metabolism, contributing to a tumor-restraining status. Further co-treatment with carboplatin triggered RIP3/TNFa dependent necroptosis in ex vivo cells accompanied by differential expression of immunosuppressive miR-146/miR-210 regulators in metastatic lung cancer patients. Overall, these findings demonstrate the multifaceted roles of Kras-derived exosomes in sustaining lung immunosuppressive metastasis and provide new opportunities for effective metastasis inhibition, especially in chemoresistant tumors.

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.

Exosomes released upon mitochondrial ASncmtRNA knockdown reduce tumorigenic properties of malignant breast cancer cells

During intercellular communication, cells release extracellular vesicles such as exosomes, which contain proteins, ncRNAs and mRNAs that can influence proliferation and/or trigger apoptosis in recipient cells, and have been proposed to play an essential role in promoting invasion of tumor cells and in the preparation of metastatic niches. Our group proposed the antisense non-coding mitochondrial RNA (ASncmtRNA) as a new target for cancer therapy. ASncmtRNA knockdown using an antisense oligonucleotide (ASO-1537S) causes massive death of tumor cells but not normal cells and strongly reduces metastasis in mice. In this work, we report that exosomes derived from ASO-1537S-treated MDA-MB-231 breast cancer cells (Exo-1537S) inhibits tumorigenesis of recipient cells, in contrast to exosomes derived from control-ASO-treated cells (Exo-C) which, in contrast, enhance these properties. Furthermore, an in vivo murine peritoneal carcinomatosis model showed that Exo-1537S injection reduced tumorigenicity compared to controls. Proteomic analysis revealed the presence of Lactadherin and VE-Cadherin in exosomes derived from untreated cells (Exo-WT) and Exo-C but not in Exo-1537S, and the latter displayed enrichment of proteasomal subunits. These results suggest a role for these proteins in modulation of tumorigenic properties of exosome-recipient cells. Our results shed light on the mechanisms through which ASncmtRNA knockdown affects the preparation of breast cancer metastatic niches in a peritoneal carcinomatosis model.

Tumour-derived extracellular vesicles in blood of metastatic cancer patients associate with overall survival

BACKGROUND

Circulating tumour cells (CTCs) in blood associate with overall survival (OS) of cancer patients, but they are detected in extremely low numbers. Large tumour-derived extracellular vesicles (tdEVs) in castration-resistant prostate cancer (CRPC) patients are present at around 20 times higher frequencies than CTCs and have equivalent prognostic power. In this study, we explored the presence of tdEVs in other cancers and their association with OS.

METHODS

The open-source ACCEPT software was used to automatically enumerate tdEVs in digitally stored CellSearch® images obtained from previously reported CTC studies evaluating OS in 190 CRPC, 450 metastatic colorectal cancer (mCRC), 179 metastatic breast cancer (MBC) and 137 non-small cell lung cancer (NSCLC) patients before the initiation of a new treatment.

RESULTS

Presence of unfavourable CTCs and tdEVs is predictive of OS, with respective hazard ratios (HRs) of 2.4 and 2.2 in CRPC, 2.7 and 2.2 in MBC, 2.3 and 1.9 in mCRC and 2.0 and 2.4 in NSCLC, respectively.

CONCLUSIONS

tdEVs have equivalent prognostic value as CTCs in the investigated metastatic cancers. CRPC, mCRC, and MBC (but not NSCLC) patients with favourable CTC counts can be further prognostically stratified using tdEVs. Our data suggest that tdEVs could be used in clinical decision-making.

Communication in tiny packages: Exosomes as means of tumor-stroma communication

Tumor-derived exosomes are nano-sized vesicles acting as multi-signal devices influencing tumor growth at local and distant sites. Exosomes are derived from the endolysosomal compartment and can shuttle diverse biomolecules like nucleic acids (microRNAs and DNA fragments), lipids, proteins, and even pharmacological compounds from a donor cell to recipient cells. The transfer of cargo to recipient cells enables tumor-derived exosomes to influence diverse cellular functions like proliferation, cell survival, and migration in recipient cells, highlighting tumor-derived exosomes as important players in communication within the tumor microenvironment and at distant sites. In this review, we discuss the mechanisms associated with exosome biogenesis and cargo sorting. In addition, we highlight the communication of tumor-derived exosomes in the tumor microenvironment during different phases of tumor development, focusing on angiogenesis, immune escape mechanisms, drug resistance, and metastasis.

Extracellular Vesicles in the Tumor Microenvironment: Various Implications in Tumor Progression

Extracellular vesicle (EV) shedding is a biologically conserved cellular process across virtually every cell type. In cancer, EVs shed from tumor and stromal cells to the tumor microenvironment play a major role in determining tumor fate, which to a large extent is dictated by the biologically active cargo contained in EVs. Current understanding of various cancer-associated EVs has enabled the outlining of mechanistic connections between cargo and tumor-promoting functions. In this chapter, we describe examples of EV-mediated communication between tumor cells and stromal cells, highlighting the molecular constituents responsible for pro-tumorigenic effects. Furthermore, we discuss the roles of matrix-degrading EVs in cell invasion. Finally, we summarize research on the potential use of EVs as a novel approach to cancer therapeutics.

Heparanase Involvement in Exosome Formation

Exosomes are secreted vesicles involved in signaling processes. The biogenesis of a class of these extracellular vesicles depends on syntenin, and on the interaction of this cytosolic protein with syndecans. Heparanase, largely an endosomal enzyme, acts as a regulator of the syndecan-syntenin-exosome biogenesis pathway. The upregulation of syntenin and heparanase in cancers may support the suspected roles of exosomes in tumor biology.

Exosomes: Dynamic Mediators of Extracellular Communication in the Tumor Microenvironment

It is becoming increasingly recognized that the tumor microenvironment significantly contributes to the development, progression, and metastasis of cancer and also plays a role in response to treatment. The tumor microenvironment is a complex and heterogeneous niche comprised of stromal cells, cancer cells, blood vessels, areas of hypoxia and necrotic tissue, fibrosis, and extracellular matrix. Cellular communication takes place within the tumor microenvironment, both via cell to cell contact, and through extracellular mechanisms such as exosomal signaling. Exosomes are very small membrane-bound vesicles that have been shown to play key roles in the progression of cancer including modulation of the tumor microenvironment through the induction of angiogenesis, the transfer of genetic information that confers drug resistance, and increased cell migration, invasion, proliferation, and survival, as well as the modulation of immune cell interactions. The role of exosomes in several different cancers has been investigated. In the context of osteosarcoma, understanding how exosomes may modulate the tumor microenvironment to support metastatic growth particularly in the lung, the most common site of metastases, may identify novel therapeutic targets for relapsed patients.

Engineering Extracellular Vesicles as Nanotherapeutics for Regenerative Medicine

Long thought of to be vesicles that primarily recycled waste biomolecules from cells, extracellular vesicles (EVs) have now emerged as a new class of nanotherapeutics for regenerative medicine. Recent studies have proven their potential as mediators of cell proliferation, immunomodulation, extracellular matrix organization and angiogenesis, and are currently being used as treatments for a variety of diseases and injuries. They are now being used in combination with a variety of more traditional biomaterials and tissue engineering strategies to stimulate tissue repair and wound healing. However, the clinical translation of EVs has been greatly slowed due to difficulties in EV isolation and purification, as well as their limited yields and functional heterogeneity. Thus, a field of EV engineering has emerged in order to augment the natural properties of EVs and to recapitulate their function in semi-synthetic and synthetic EVs. Here, we have reviewed current technologies and techniques in this growing field of EV engineering while highlighting possible future applications for regenerative medicine.

Actin and Actin-Associated Proteins in Extracellular Vesicles Shed by Osteoclasts

Extracellular vesicles (EVs) are shed by all eukaryotic cells and have emerged as important intercellular regulators. EVs released by osteoclasts were recently identified as important coupling factors in bone remodeling. They are shed as osteoclasts resorb bone and stimulate osteoblasts to form bone to replace the bone resorbed. We reported the proteomic content of osteoclast EVs with data from two-dimensional, high resolution liquid chromatography/mass spectrometry. In this article, we examine in detail the actin and actin-associated proteins found in osteoclast EVs. Like EVs from other cell types, actin and various actin-associated proteins were abundant. These include components of the polymerization machinery, myosin mechanoenzymes, proteins that stabilize or depolymerize microfilaments, and actin-associated proteins that are involved in regulating integrins. The selective incorporation of actin-associated proteins into osteoclast EVs suggests that they have roles in the formation of EVs and/or the regulatory signaling functions of the EVs. Regulating integrins so that they bind extracellular matrix tightly, in order to attach EVs to the extracellular matrix at specific locations in organs and tissues, is one potential active role for actin-associated proteins in EVs.

Unraveling the Molecular Signature of Extracellular Vesicles From Endometrial-Derived Mesenchymal Stem Cells: Potential Modulatory Effects and Therapeutic Applications

Endometrial-derived Mesenchymal Stem Cells (endMSCs) are involved in the regeneration and remodeling of human endometrium, being considered one of the most promising candidates for stem cell-based therapies. Their therapeutic effects have been found to be mediated by extracellular vesicles (EV-endMSCs) with pro-angiogenic, anti-apoptotic, and immunomodulatory effects. Based on that, the main goal of this study was to characterize the proteome and microRNAome of these EV-endMSCs by proteomics and transcriptomics approaches. Additionally, we hypothesized that inflammatory priming of endMSCs may contribute to modify the therapeutic potential of these vesicles. High-throughput proteomics revealed that 617 proteins were functionally annotated as Extracellular exosome (GO:0070062), corresponding to the 70% of the EV-endMSC proteome. Bioinformatics analyses allowed us to identify that these proteins were involved in adaptive/innate immune response, complement activation, antigen processing/presentation, negative regulation of apoptosis, and different signaling pathways, among others. Of note, multiplexed quantitative proteomics and Systems Biology analyses showed that IFNγ priming significantly modulated the protein profile of these vesicles. As expected, proteins involved in antigen processing and presentation were significantly increased. Interestingly, immunomodulatory proteins, such as CSF1, ERAP1, or PYCARD were modified. Regarding miRNAs expression profile in EV-endMSCs, Next-Generation Sequencing (NGS) showed that the preferred site of microRNAome targeting was the nucleus (n = 371 microTargets), significantly affecting signal transduction (GO:0007165), cell proliferation (GO:0008283), and apoptotic processes (GO:0006915), among others. Interestingly, NGS analyses highlighted that several miRNAs, such as hsa-miR-150-5p or hsa-miR-196b-5p, were differentially expressed in IFNγ-primed EV-endMSCs. These miRNAs have a functional involvement in glucocorticoid receptor signaling, IL-6/8/12 signaling, and in the role of macrophages. In summary, these results allowed us to understand the complexity of the molecular networks in EV-endMSCs and their potential effects on target cells. To our knowledge, this is the first comprehensive study based on proteomic and genomic approaches to unravel the therapeutic potential of these extracellular vesicles, that may be used as immunomodulatory effectors in the treatment of inflammatory conditions.

Decoding the Biology of Exosomes in Metastasis

Metastasis is the leading cause of cancer mortality. Cancer cells must adapt to colonize and thrive at the metastatic site. The modulation of the receptive organ microenvironment is a key event in the adaptation process and is partially accomplished at a distance by the primary tumor. Exosomes, a subclass of extracellular vesicles (EVs), are distal mediators of communication that carry genetic and molecular information to neighboring and distant cells. Cancer exosomes have been involved in restructuring metastatic sites to support cancer cell colonization. In this article, we discuss the role of exosomes in the metastatic process.

Integrin β1-enriched extracellular vesicles mediate monocyte adhesion and promote liver inflammation in murine NASH

BACKGROUND & AIMS

Hepatic recruitment of monocyte-derived macrophages (MoMFs) contributes to the inflammatory response in non-alcoholic steatohepatitis (NASH). However, how hepatocyte lipotoxicity promotes MoMF inflammation is unclear. Here we demonstrate that lipotoxic hepatocyte-derived extracellular vesicles (LPC-EVs) are enriched with active integrin β₁ (ITGβ₁), which promotes monocyte adhesion and liver inflammation in murine NASH.

METHODS

Hepatocytes were treated with either vehicle or the toxic lipid mediator lysophosphatidylcholine (LPC); EVs were isolated from the conditioned media and subjected to proteomic analysis. C57BL/6J mice were fed a diet rich in fat, fructose, and cholesterol (FFC) to induce NASH. Mice were treated with anti-ITGβ₁ neutralizing antibody (ITGβ₁Ab) or control IgG isotype.

RESULTS

Ingenuity® Pathway Analysis of the LPC-EV proteome indicated that ITG signaling is an overrepresented canonical pathway. Immunogold electron microscopy and nanoscale flow cytometry confirmed that LPC-EVs were enriched with activated ITGβ₁. Furthermore, we showed that LPC treatment in hepatocytes activates ITGβ₁ and mediates its endocytic trafficking and sorting into EVs. LPC-EVs enhanced monocyte adhesion to liver sinusoidal cells, as observed by shear stress adhesion assay. This adhesion was attenuated in the presence of ITGβ₁Ab. FFC-fed, ITGβ₁Ab-treated mice displayed reduced inflammation, defined by decreased hepatic infiltration and activation of proinflammatory MoMFs, as assessed by immunohistochemistry, mRNA expression, and flow cytometry. Likewise, mass cytometry by time-of-flight on intrahepatic leukocytes showed that ITGβ₁Ab reduced levels of infiltrating proinflammatory monocytes. Furthermore, ITGβ₁Ab treatment significantly ameliorated liver injury and fibrosis.

CONCLUSIONS

Lipotoxic EVs mediate monocyte adhesion to LSECs mainly through an ITGβ₁-dependent mechanism. ITGβ₁Ab ameliorates diet-induced NASH in mice by reducing MoMF-driven inflammation, suggesting that blocking ITGβ₁ is a potential anti-inflammatory therapeutic strategy in human NASH.

LAY SUMMARY

Herein, we report that a cell adhesion molecule termed integrin β₁ (ITGβ₁) plays a key role in the progression of non-alcoholic steatohepatitis (NASH). ITGβ₁ is released from hepatocytes under lipotoxic stress as a cargo of extracellular vesicles, and mediates monocyte adhesion to liver sinusoidal endothelial cells, which is an essential step in hepatic inflammation. In a mouse model of NASH, blocking ITGβ₁ reduces liver inflammation, injury and fibrosis. Hence, ITGβ₁ inhibition may serve as a new therapeutic strategy for NASH.

Exosomes and Ectosomes in Intercellular Communication

Exosomes and ectosomes, two distinct types of extracellular vesicles generated by all types of cell, play key roles in intercellular communication. The formation of these vesicles depends on local microdomains assembled in endocytic membranes for exosomes and in the plasma membrane for ectosomes. These microdomains govern the accumulation of proteins and various types of RNA associated with their cytosolic surface, followed by membrane budding inward for exosome precursors and outward for ectosomes. A fraction of endocytic cisternae filled with vesicles - multivesicular bodies - are later destined to undergo regulated exocytosis, leading to the extracellular release of exosomes. In contrast, the regulated release of ectosomes follows promptly after their generation. These two types of vesicle differ in size - 50-150 nm for exosomes and 100-500 nm for ectosomes - and in the mechanisms of assembly, composition, and regulation of release, albeit only partially. For both exosomes and ectosomes, the surface and luminal cargoes are heterogeneous when comparing vesicles released by different cell types or by single cells in different functional states. Upon release, the two types of vesicle navigate through extracellular fluid for varying times and distances. Subsequently, they interact with recognized target cells and undergo fusion with endocytic or plasma membranes, followed by integration of vesicle membranes into their fusion membranes and discharge of luminal cargoes into the cytosol, resulting in changes to cellular physiology. After fusion, exosome/ectosome components can be reassembled in new vesicles that are then recycled to other cells, activating effector networks. Extracellular vesicles also play critical roles in brain and heart diseases and in cancer, and are useful as biomarkers and in the development of innovative therapeutic approaches.

Role of Extracellular Vesicles in Renal Inflammation and Fibrosis

Extracellular vesicles (EVs) are the membrane-surrounded structures released by almost all types of cells. Accumulating evidences have suggested that EVs secretion is enhanced under stress conditions and have been associated with a large wide of cellular physiological and pathological processes. In this part, recent understanding about the generation and biological function of EVs was reviewed. Moreover, the role of EVs in renal inflammation and fibrosis and future challenges of EVs study in kidney disease were discussed.

Exosomes as Carriers for Antitumor Therapy

Exosomes are bilayer vesicles with particle sizes between 50 and 150 nm. Owing to their bilayer membrane structure, cell-to-cell communication, and good absorbability, exosomes are increasingly used as carriers for drug delivery through phospholipid membrane structures to lesion sites with enhanced targeting. Exosome sources and drug-loading methods are important factors affecting their use as drug carriers. There are various ways to pack species in exosomes, and researchers are constantly seeking new and improved approaches. In both in vivo and in vitro evaluations, exosomal vectors have achieved good antitumor efficacies. Despite the importance of exosomes as drug delivery systems with accurate targeting ability and biocompatibility, improvements are needed to facilitate their widespread clinical use. This review focuses on the preparation of exosomes as carriers and their utilization in antitumor research.

Human perivascular stem cell-derived extracellular vesicles mediate bone repair

The vascular wall is a source of progenitor cells that are able to induce skeletal repair, primarily by paracrine mechanisms. Here, the paracrine role of extracellular vesicles (EVs) in bone healing was investigated. First, purified human perivascular stem cells (PSCs) were observed to induce mitogenic, pro-migratory, and pro-osteogenic effects on osteoprogenitor cells while in non-contact co-culture via elaboration of EVs. PSC-derived EVs shared mitogenic, pro-migratory, and pro-osteogenic properties of their parent cell. PSC-EV effects were dependent on surface-associated tetraspanins, as demonstrated by EV trypsinization, or neutralizing antibodies for CD9 or CD81. Moreover, shRNA knockdown in recipient cells demonstrated requirement for the CD9/CD81 binding partners IGSF8 and PTGFRN for EV bioactivity. Finally, PSC-EVs stimulated bone repair, and did so via stimulation of skeletal cell proliferation, migration, and osteodifferentiation. In sum, PSC-EVs mediate the same tissue repair effects of perivascular stem cells, and represent an 'off-the-shelf' alternative for bone tissue regeneration.

The Role of Exosomes in Pancreatic Cancer

Pancreatic cancer remains one of the deadliest cancers in the world, as a consequence of late diagnosis, early metastasis and limited response to chemotherapy, under which conditions the potential mechanism of pancreatic cancer progression requires further study. Exosomes are membrane vesicles which are important in the progression, metastasis and chemoresistance in pancreatic cancer. Additionally, they have been verified to be potential as biomarkers, targets and drug carriers for pancreatic cancer treatment. Thus, studying the role of exosomes in pancreatic cancer is significant. This paper focuses on the role of exosomes in the proliferation, metastasis and chemoresistance, as well as their potential applications for pancreatic cancer.

SILAC-Based Quantification of TGFBR2-Regulated Protein Expression in Extracellular Vesicles of Microsatellite Unstable Colorectal Cancers

Microsatellite unstable (MSI) colorectal cancers (CRCs) are characterized by mutational inactivation of Transforming Growth Factor Beta Receptor Type 2 (TGFBR2). TGFBR2-deficient CRCs present altered target gene and protein expression. Such cellular alterations modulate the content of CRC-derived extracellular vesicles (EVs). EVs function as couriers of proteins, nucleic acids, and lipids in intercellular communication. At a qualitative level, we have previously shown that TGFBR2 deficiency causes overall alterations in the EV protein content. To deepen the basic understanding of altered protein dynamics, this work aimed to determine TGFBR2-dependent EV protein signatures in a quantitative manner. Using a stable isotope labeling with amino acids in cell culture (SILAC) approach for mass spectrometry-based quantification, 48 TGFBR2-regulated proteins were identified in MSI CRC-derived EVs. Overall, TGFBR2 deficiency caused upregulation of several EV proteins related to the extracellular matrix and nucleosome as well as downregulation of proteasome-associated proteins. The present study emphasizes the general overlap of proteins between EVs and their parental CRC cells but also highlights the impact of TGFBR2 deficiency on EV protein composition. From a clinical perspective, TGFBR2-regulated quantitative differences of protein expression in EVs might nominate novel biomarkers for liquid biopsy-based MSI typing in the future.

Matrix stiffness regulates microvesicle-induced fibroblast activation

Extracellular vesicles released by cancer cells have recently been implicated in the differentiation of stromal cells to their activated, cancer-supporting states. Microvesicles, a subset of extracellular vesicles released from the plasma membrane of cancer cells, contain biologically active cargo, including DNA, mRNA, and miRNA, which are transferred to recipient cells and induce a phenotypic change in behavior. While it is known that microvesicles can alter recipient cell phenotype, little is known about how the physical properties of the tumor microenvironment affect fibroblast response to microvesicles. Here, we utilized cancer cell-derived microvesicles and synthetic substrates designed to mimic the stiffness of the tumor and tumor stroma to investigate the effects of microvesicles on fibroblast phenotype as a function of the mechanical properties of the microenvironment. We show that microvesicles released by highly malignant breast cancer cells cause an increase in fibroblast spreading, α-smooth muscle actin expression, proliferation, cell-generated traction force, and collagen gel compaction. Notably, our data indicate that these phenotypic changes occur only on stiff matrices mimicking the stiffness of the tumor periphery and are dependent on the cell type from which the microvesicles are shed. Overall, these results show that the effects of cancer cell-derived microvesicles on fibroblast activation are regulated by the physical properties of the microenvironment, and these data suggest that microvesicles may have a more robust effect on fibroblasts located at the tumor periphery to influence cancer progression.

New insights into extracellular vesicle biogenesis and function

It is becoming increasingly evident that most cell types are capable of forming and releasing multiple distinct classes of membrane-enclosed packages, referred to as extracellular vesicles (EVs), as a form of intercellular communication. Microvesicles (MVs) represent one of the major classes of EVs and are formed by the outward budding of the plasma membrane. The second major class of EVs, exosomes, are produced as components of multivesicular bodies (MVBs) and are released from cells when MVBs fuse with the cell surface. Both MVs and exosomes have been shown to contain proteins, RNA transcripts, microRNAs and even DNA that can be transferred to other cells and thereby trigger a broad range of cellular activities and biological responses. However, EV biogenesis is also frequently de-regulated in different pathologies, especially cancer, where MVs and exosomes have been suggested to promote tumor cell growth, therapy resistance, invasion and even metastasis. In this Review, we highlight some of the recent advances in this rapidly emerging and exciting field of cell biology, focusing on the underlying mechanisms that drive MV and exosome formation and release, with a particular emphasis on how EVs potentially impact different aspects of cancer progression and stem cell biology.

Salivary Extracellular Vesicle-Associated exRNA as Cancer Biomarker

Extracellular vesicles (EVs) secreted in biological fluids contain several transcripts of the cell of origin, which may modify the functions and phenotype of proximal and distant cells. Cancer-derived EVs may promote a favorable microenvironment for cancer growth and invasion by acting on stroma and endothelial cells and may favor metastasis formation. The transcripts contained in cancer EVs may be exploited as biomarkers. Protein and extracellular RNA (exRNA) profiling in patient bio-fluids, such as blood and urine, was performed to identify molecular features with potential diagnostic and prognostic values. EVs are concentrated in saliva, and salivary EVs are particularly enriched in exRNAs. Several studies were focused on salivary EVs for the detection of biomarkers either of non-oral or oral cancers. The present paper provides an overview of the available studies on the diagnostic potential of exRNA profiling in salivary EVs.

Exosomes, metastases, and the miracle of cancer stem cell markers

Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.

Role of extracellular vesicles in stem cell biology

The extracellular vesicles (EVs) are membrane vesicles carrying proteins, nucleic acids, and bioactive lipids of the cell of origin. These vesicles released within the extracellular space and entering into the circulation may transfer their cargo to neighboring or distant cells and induce phenotypical and functional changes that may be relevant in several physiopathological conditions. In an attempt to define the biological properties of EVs, several investigations have focused on their cargo and on the effects elicited in recipient cells. EVs have been involved in modulation of tumor microenvironment and behavior, as well as in the immune and inflammatory response. In the present review, we address the paracrine action of EVs released by stem cells and their potential involvement in the activation of regenerative programs in injured cells.

Exosomes in cancer development, metastasis, and immunity

Exosomes play essential roles in intercellular communications. The exosome was discovered in 1983, when it was found that reticulocytes release 50-nm small vesicles carrying transferrin receptors into the extracellular space. Since then, our understanding of the mechanism and function of the exosome has expanded exponentially that has transformed our perspective of inter-cellular exchanges and the molecular mechanisms that underlie disease progression. Cancer cells generally produce more exosomes than normal cells, and exosomes derived from cancer cells have a strong capacity to modify both local and distant microenvironments. In this review, we summarize the functions of exosomes in cancer development, metastasis, and anti-tumor or pro-tumor immunity, plus their application in cancer treatment and diagnosis/prognosis. Although the exosome field has rapidly advanced, we still do not fully understand the regulation and function of exosomes in detail and still face many challenges in their clinical application. Continued discoveries in this field will bring novel insights on intercellular communications involved in various biological functions and disease progression, thus empowering us to effectively tackle accompanying clinical challenges.

Metastasis inhibition in breast cancer by targeting cancer cell extravasation

The spread of cells from primary tumors toward distant tissues and organs, also known as metastasis, is responsible for most cancer-associated deaths. The metastasis cascade comprises a series of events, characterized by the displacement of tumor cells (TCs) from the primary tumor to distant organs by traveling through the bloodstream, and their subsequent colonization. The first step in metastasis involves loss of cell-cell and cell-matrix adhesions, increased invasiveness and migratory abilities, leading to intravasation of TCs into the blood or lymphatic vessels. Stationary TCs must undergo the process of epithelial-mesenchymal transition in order to achieve this migratory and invasive phenotype. Circulating tumor cells that have survived in the circulation and left the blood or lymphatic vessels will reach distant sites where they may stay dormant for many years or grow to form secondary tumors. To do this, cells need to go through the mesenchymal-epithelial transition to revert the phenotype in order to regain epithelial cell-to-cell junctions, grow and become a clinically relevant and detectable tumor mass. This work will review the main steps of the metastatic cascade and describe some strategies to inhibit metastasis by reducing cancer cell extravasation presenting recent studies in the context of breast cancer.

Biodistribution of gadolinium- and near infrared-labeled human umbilical cord mesenchymal stromal cell-derived exosomes in tumor bearing mice

We speculate that exosomes derived from human umbilical cord mesenchymal stromal cells (HUC-MSCs) will accumulate within tumors and have the potential for both tumor location or drug delivery.

Methods: To determine proof of concept, HUC-MSC exosomes were labeled with an MRI contrast agent, gadolinium, or a near infrared dye. Exosome accumulation within ectopic osteosarcoma tumor-bearing mice was determined by 14.1 T MRI or bioimaging over 24-48 h after injection. In vitro studies examine the accumulation and physiological effect of exosomes on human and mouse osteosarcoma cell lines by MTT assay, confocal microscopy, and flow cytometry.

Results: Systemic HUC-MSC exosomes accumulated continuously in tumor over a 24-48 h post-injection period. In contrast, synthetic lipid nanoparticles accumulate in tumor only for the first 3 h post-injection.

Conclusion: These results suggest that HUC-MSCs exosomes accumulate within human or mouse osteosarcoma cells in vitro and in vivo over a 24 to 48 h after infusion.

Suppression of Exosomal PD-L1 Induces Systemic Anti-tumor Immunity and Memory

PD-L1 on the surface of tumor cells binds its receptor PD-1 on effector T cells, thereby suppressing their activity. Antibody blockade of PD-L1 can activate an anti-tumor immune response leading to durable remissions in a subset of cancer patients. Here, we describe an alternative mechanism of PD-L1 activity involving its secretion in tumor-derived exosomes. Removal of exosomal PD-L1 inhibits tumor growth, even in models resistant to anti-PD-L1 antibodies. Exosomal PD-L1 from the tumor suppresses T cell activation in the draining lymph node. Systemically introduced exosomal PD-L1 rescues growth of tumors unable to secrete their own. Exposure to exosomal PD-L1-deficient tumor cells suppresses growth of wild-type tumor cells injected at a distant site, simultaneously or months later. Anti-PD-L1 antibodies work additively, not redundantly, with exosomal PD-L1 blockade to suppress tumor growth. Together, these findings show that exosomal PD-L1 represents an unexplored therapeutic target, which could overcome resistance to current antibody approaches.

Exosomes: composition, biogenesis, and mechanisms in cancer metastasis and drug resistance

Tumor-derived exosomes (TDEs) participate in formation and progression of different cancer processes, including tumor microenvironment (TME) remodeling, angiogenesis, invasion, metastasis and drug-resistance. Exosomes initiate or suppress various signaling pathways in the recipient cells via transmitting heterogeneous cargoes. In this review we discuss exosome biogenesis, exosome mediated metastasis and chemoresistance. Furthermore, tumor derived exosomes role in tumor microenvironment remodeling, and angiogenesis is reviewed. Also, exosome induction of epithelial mesenchymal transition (EMT) is highlighted. More importantly, we discuss extensively how exosomes regulate drug resistance in several cancers. Thus, understanding exosome biogenesis, their contents and the molecular mechanisms and signaling pathways that are responsible for metastasis and drug-resistance mediated by TDEs may help to devise novel therapeutic approaches for cancer progression particularly to overcome therapy-resistance and preventing metastasis as major factors of cancer mortality.

Non-canonical processes that shape the cell migration landscape

Migration is a vital, intricate, and multi-faceted process that involves the entire cell, entails the integration of multiple external cues and, at times, necessitates high-level coordination among fields of cells that can be physically attached or not, depending on the physiological setting. Recent advances have highlighted the essential role of cellular components that have not been traditionally considered when studying cell migration. This review details how much we recently learned by studying the role of intermediate filaments, the nucleus, extracellular vesicles, and mitochondria during cell migration.

Extracellular vesicles-mediated intercellular communication: roles in the tumor microenvironment and anti-cancer drug resistance

The tumor microenvironment represents a complex network, in which tumor cells not only communicate with each other but also with stromal and immune cells. Current research has demonstrated the vital role of the tumor microenvironment in supporting tumor phenotype via a sophisticated system of intercellular communication through direct cell-to-cell contact or by classical paracrine signaling loops of cytokines or growth factors. Recently, extracellular vesicles have emerged as an important mechanism of cellular interchange of bioactive molecules. Extracellular vesicles isolated from tumor and stromal cells have been implicated in various steps of tumor progression, such as proliferation, angiogenesis, metastasis, and drug resistance. Inhibition of extracellular vesicles secretion, and thus of the transfer of oncogenic molecules, holds promise for preventing tumor growth and drug resistance. This review focuses on the role of extracellular vesicles in modulating the tumor microenvironment by addressing different aspects of the bidirectional interactions among tumor and tumor-associated cells. The contribution of extracellular vesicles to drug resistance will also be discussed as well as therapeutic strategies targeting extracellular vesicles production for the treatment of cancer.

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

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

MicroRNAs and Long Non-Coding RNAs and Their Hormone-Like Activities in Cancer

Hormones are messengers circulating in the body that interact with specific receptors on the cell membrane or inside the cells and regulate, at a distal site, the activities of specific target organs. The definition of hormone has evolved in the last years. Hormones are considered in the context of cell–cell communication and mechanisms of cellular signaling. The best-known mechanisms of this kind are chemical receptor-mediated events, the cell–cell direct interactions through synapses, and, more recently, the extracellular vesicle (EV) transfer between cells. Recently, it has been extensively demonstrated that EVs are used as a way of communication between cells and that they are transporters of specific messenger signals including non-coding RNAs (ncRNAs) such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Circulating ncRNAs in body fluids and extracellular fluid compartments may have endocrine hormone-like effects because they can act at a distance from secreting cells with widespread consequences within the recipient cells. Here, we discuss and report examples of the potential role of miRNAs and lncRNAs as mediator for intercellular communication with a hormone-like mechanism in cancer.

Fibronectin on the Surface of Extracellular Vesicles Mediates Fibroblast Invasion

Extracellular vesicles (EVs) are endosome and plasma membrane-derived nano-sized vesicles that participate in intercellular signaling. Although EV cargo may signal via multiple mechanisms, how signaling components on the surface of EVs mediate cellular signaling is less well understood. In this study, we show that fibroblast-derived EVs carry fibronectin on the vesicular surface, as evidenced by mass spectrometry-based proteomics (Sequential Window Acquisition of all Theoretical Mass Spectra) and flow-cytometric analyses. Fibroblasts undergoing replicative senescence or transforming growth factor β1-induced senescence and fibroblasts isolated from human subjects with an age-related lung disorder, idiopathic pulmonary fibrosis, secreted higher numbers of EVs than their respective controls. Fibroblast-derived EVs induced an invasive phenotype in recipient fibroblasts. This invasive fibroblast phenotype was dependent on EV surface localization of fibronectin, interaction with the fibronectin receptor α5β1 integrin, and activation of invasion-associated signaling pathways involving focal adhesion kinase and Src family kinases. EVs in the cellular supernatant, unbound to the extracellular matrix, were capable of mediating invasion signaling on recipient fibroblasts, supporting a direct interaction of EV surface fibronectin with the plasma membrane of recipient cells. Together, these studies uncover a novel mechanism of EV signaling of fibroblast invasion that may be relevant in the pathogenesis of fibrotic diseases and cancer.

Subtypes of tumour cell-derived small extracellular vesicles having differently externalized phosphatidylserine

Phosphatidylserine (PS) has skewed distributions in the plasma membrane and is preferentially located in the inner leaflet of normal cells. Tumour cells, however, expose PS at the outer leaflet of cell surfaces, thereby potentially modulating the bio-signalling of cells. Interestingly, exosomes - or, more properly, small extracellular vesicles (sEVs) - which are secreted from tumour cells, are enriched with externalized PS, have been proposed as being involved in the progression of cancers, and could be used as a marker for tumour diagnostics. However, the sEV fractions prepared from various methods are composed of different subtypes of vesicles, and knowledge about the subtypes enriched with exposed PS is still limited. Here, we differentiated sEVs from cancer cell lines by density gradient centrifugation and characterized the separated fractions by using gold-labelling of PS in atomic force microscopy, thrombin generation assay, size and zeta potential measurements, and western blot analysis. These analyses revealed a previously unreported PS⁺-enriched sEV subtype, which is characterized by a lower density than that of canonical exosomes (1.06 g/ml vs. 1.08 g/ml), larger size (122 nm vs. 105 nm), more negative zeta potential (-28 mV vs. -21 mV), and lower abundance of canonical exosomal markers. The identification of the PS-exposed subtype of sEVs will provide deeper insight into the role of EVs in tumour biology and enhance the development of EV-based tumour diagnosis and therapy.

Live Tracking of Inter-organ Communication by Endogenous Exosomes In Vivo

Extracellular vesicles (EVs) are released by most cell types but providing evidence for their physiological relevance remains challenging due to a lack of appropriate model organisms. Here, we developed an in vivo model to study EV function by expressing CD63-pHluorin in zebrafish embryos. A combination of imaging methods and proteomic analysis allowed us to study biogenesis, composition, transfer, uptake, and fate of individual endogenous EVs. We identified a subpopulation of EVs with exosome features, released in a syntenin-dependent manner from the yolk syncytial layer into the blood circulation. These exosomes are captured, endocytosed, and degraded by patrolling macrophages and endothelial cells in the caudal vein plexus (CVP) in a scavenger receptor- and dynamin-dependent manner. Interference with exosome biogenesis affected CVP growth, suggesting a role in trophic support. Altogether, our work represents a system for studying endogenous EV function in vivo with high spatiotemporal accuracy, demonstrating functional inter-organ communication by exosomes.

Quantitative Proteomic Analysis of Small and Large Extracellular Vesicles (EVs) Reveals Enrichment of Adhesion Proteins in Small EVs

Extracellular vesicles (EVs) are important mediators of cell-cell communication due to their cargo content of proteins, lipids, and RNAs. We previously reported that small EVs (SEVs) called exosomes promote directed and random cell motility, invasion, and serum-independent growth. In contrast, larger EVs (LEVs) were not active in those assays, but might have unique functional properties. In order to identify protein cargos that may contribute to different functions of SEVs and LEVs, we used isobaric tags for relative and absolute quantitation (iTRAQ)-liquid chromatography (LC) tandem mass spectrometry (MS) on EVs isolated from a colon cancer cell line. Bioinformatics analyses revealed that SEVs are enriched in proteins associated with cell-cell junctions, cell-matrix adhesion, exosome biogenesis machinery, and various signaling pathways. In contrast, LEVs are enriched in proteins associated with ribosome and RNA biogenesis, processing, and metabolism. Western blot analysis of EVs purified from two different cancer cell types confirmed the enrichment of cell-matrix and cell-cell adhesion proteins in SEVs. Consistent with those data, we found that cells exhibit enhanced adhesion to surfaces coated with SEVs compared to an equal protein concentration of LEVs. These data suggest that a major function of SEVs is to promote cellular adhesion.

Connexins and Integrins in Exosomes

Connexins and integrins, the two structurally and functionally distinct families of transmembrane proteins, have been shown to be inter-connected by various modes of cross-talk in cells, such as direct physical coupling via lateral contact, indirect physical coupling via actin and actin-binding proteins, and functional coupling via signaling cascades. This connexin-integrin cross-talk exemplifies a biologically important collaboration between channels and adhesion receptors in cells. Exosomes are biological lipid-bilayer nanoparticles secreted from virtually all cells via endosomal pathways into the extracellular space, thereby mediating intercellular communications across a broad range of health and diseases, including cancer progression and metastasis, infection and inflammation, and metabolic deregulation. Connexins and integrins are embedded in the exosomal membranes and have emerged as critical regulators of intercellular communication. This concise review article will explain and discuss recent progress in better understanding the roles of connexins, integrins, and their cross-talk in cells and exosomes.

The role of extracellular vesicles in cancer microenvironment and metastasis: myths and challenges

The concept of vesicles or cell debris released by cancer cells to promote metastasis is not new, but the mechanisms used to currently ascribe their impact in metastasis are of intense debate. A significant increase in reports describing the role of cancer-derived EVs in cancer metastasis has been followed by a growing amount of uncertainty behind these claims. This review will delve into the role of EVs in promoting cancer metastasis by relying on a balanced perspective that looks at challenges faced previously by extracellular vesicle biologists, current technical limitations in the field, and overlooked physiologic mechanisms that may play a confounding role. This review will also discuss how certain experimental approaches are misleading which ultimately lead to overly optimistic mechanisms that have minimally contributed to the pathophysiology of metastasis.

Exosomes from Nischarin-Expressing Cells Reduce Breast Cancer Cell Motility and Tumor Growth

Exosomes are small extracellular microvesicles that are secreted by cells when intracellular multivesicular bodies fuse with the plasma membrane. We have previously demonstrated that Nischarin inhibits focal adhesion formation, cell migration, and invasion, leading to reduced activation of focal adhesion kinase. In this study, we propose that the tumor suppressor Nischarin regulates the release of exosomes. When cocultured on exosomes from Nischarin-positive cells, breast cancer cells exhibited reduced survival, migration, adhesion, and spreading. The same cocultures formed xenograft tumors of significantly reduced volume following injection into mice. Exosomes secreted by Nischarin-expressing tumors inhibited tumor growth. Expression of only one allele of Nischarin increased secretion of exosomes, and Rab14 activity modulated exosome secretions and cell growth. Taken together, this study reveals a novel role for Nischarin in preventing cancer cell motility, which contributes to our understanding of exosome biology. SIGNIFICANCE: Regulation of Nischarin-mediated exosome secretion by Rab14 seems to play an important role in controlling tumor growth and migration.See related commentary by McAndrews and Kalluri, p. 2099.

Dietary Chrysin Suppresses Formation of Actin Cytoskeleton and Focal Adhesion in AGE-Exposed Mesangial Cells and Diabetic Kidney: Role of Autophagy

Advanced glycation end products (AGE) play a causative role in the development of aberrant phenotypes of intraglomerular mesangial cells, contributing to acute/chronic glomerulonephritis. The aim of this study was to explore mechanistic effects of the flavonoid chrysin present in bee propolis and herbs on actin dynamics, focal adhesion, and the migration of AGE-exposed mesangial cells. The in vitro study cultured human mesangial cells exposed to 33 mM glucose and 100 μg/mL AGE-bovine serum albumin (AGE-BSA) for up to 5 days in the absence and presence of 1⁻20 μM chrysin. The in vivo study employed db/db mice orally administrated for 10 weeks with 10 mg/kg chrysin. The presence of ≥10 μM chrysin attenuated mesangial F-actin induction and bundle formation enhanced by AGE. Chrysin reduced the mesangial induction of α-smooth muscle actin (α-SMA) by glucose, and diminished the tissue α-SMA level in diabetic kidneys, indicating its blockade of mesangial proliferation. The treatment of chrysin inhibited the activation of vinculin and paxillin and the induction of cortactin, ARP2/3, fascin-1, and Ena/VASP-like protein in AGE-exposed mesangial cells. Oral administration of chrysin diminished tissue levels of cortactin and fascin-1 elevated in diabetic mouse kidneys. Mesangial cell motility was enhanced by AGE, which was markedly attenuated by adding chrysin to cells. On the other hand, chrysin dampened the induction of autophagy-related genes of beclin-1, LC3 I/II, Atg3, and Atg7 in mesangial cells exposed to AGE and in diabetic kidneys. Furthermore, chrysin reduced the mTOR activation in AGE-exposed mesangial cells and diabetic kidneys. The induction of mesangial F-actin, cortactin, and fascin-1 by AGE was deterred by the inhibition of autophagy and mTOR. Thus, chrysin may encumber diabetes-associated formation of actin bundling and focal adhesion and mesangial cell motility through disturbing autophagy and mTOR pathway.

Oncogenic Regulation of Extracellular Vesicle Proteome and Heterogeneity

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

Exosome Biochemistry and Advanced Nanotechnology for Next-Generation Theranostic Platforms

Recent marked technological advances in the field of exosome nanotechnology have provided unprecedented opportunities to bloom the developments of exosome-related biology, chemistry, pathology, and therapeutics, which have laid a solid basis for scientific community to design exosome-based nanotheranostic platforms. The unique structural/compositional/morphological characteristics of exosomes as natural nanocarriers, as well as their fascinating physicochemical/biochemical properties, which underpin their special physiopathological roles, have triggered the concept that these cell-derived nanovesicles with intrinsic biological functions can be highly competent for the establishment of next-generation nanomedicine. Herein, efforts are made to give a comprehensive overview on the recent advances of exosome nanotechnology based on the representative examples of the current state of the art of exosome-based research, ranging from their formation, biological function, preparation, and characterization to their extensive nanomedical applications. It is highly expected that the better and clearer elucidation of the fundamental principles for advanced nanotechnology in constructing exosome-based theranostic nanoplatforms, as well as integrating the intrinsic advantages of exosomes as endogenous cell-derived nanocarriers with the advanced design methodology of traditional nanomedicine, will help to unlock the innate powers of exosomes for the establishment of next-generation theranostic nanoplatforms.

The role of exosomal long non-coding RNAs in cancer drug resistance

One of the major challenges in oncology is drug resistance, which triggers relapse and shortens patients’ survival. In order to promote drug desensitization, cancer cells require the establishment of an ideal tumor microenvironment that accomplishes specific conditions. To achieve this objective, cellular communication is a key factor. Classically, cells were believed to restrictively communicate by ligand-receptor binding, physical cell-to-cell interactions and synapses. Nevertheless, the crosstalk between tumor cells and stroma cells has also been recently reported to be mediated through exosomes, the smallest extracellular vesicles, which transport a plethora of functionally active molecules, such as: proteins, lipids, messenger RNA, DNA, microRNA or long non-coding RNA (lncRNAs). LncRNAs are RNA molecules greater than 200 base pairs that are deregulated in cancer and other diseases. Exosomal lncRNAs are highly stable and can be found in several body fluids, being considered potential biomarkers for tumor liquid biopsy. Exosomal lncRNAs promote angiogenesis, cell proliferation and drug resistance. The role of exosomal lncRNAs in drug resistance affects the main treatment strategies in oncology: chemotherapy, targeted therapy, hormone therapy and immunotherapy. Overall, knowing the molecular mechanisms by which exosomal lncRNA induce pharmacologic resistance could improve further drug development and identify drug resistance biomarkers.

Exosome-Mediated Signaling in Epithelial to Mesenchymal Transition and Tumor Progression

Growing evidence points to exosomes as key mediators of cell⁻cell communication, by transferring their specific cargo (e.g., proteins, lipids, DNA and RNA molecules) from producing to receiving cells. In cancer, the regulation of the exosome-mediated intercellular communication may be reshaped, inducing relevant changes in gene expression of recipient cells in addition to microenvironment alterations. Notably, exosomes may deliver signals able to induce the transdifferentiation process known as Epithelial-to-Mesenchymal Transition (EMT). In this review, we summarize recent findings on the role of exosomes in tumor progression and EMT, highlighting current knowledge on exosome-mediated intercellular communication in tumor-niche establishment, migration, invasion, and metastasis processes. This body of evidence suggests the relevance of taking into account exosome-mediated signaling and its multifaceted aspects to develop innovative anti-tumoral therapeutic approaches.