Breast cancer-derived extracellular vesicles stimulate myofibroblast differentiation and pro-angiogenic behavior of adipose stem cells

The Chemopreventive Impact of Diet-Derived Phytochemicals on the Adipose Tissue and Breast Tumor Microenvironment Secretome

Cancer cells-derived extracellular vesicles can trigger the transformation of adipose-derived mesenchymal stem cells (ADMSC) into a pro-inflammatory, cancer-associated adipocyte (CAA) phenotype. Such secretome-mediated crosstalk between the adipose tissue and the tumor microenvironment (TME) therefore impacts tumor progression and metastatic processes. In addition, emerging roles of diet-derived phytochemicals, especially epigallocatechin-3-gallate (EGCG) among other polyphenols, in modulating exosome-mediated metabolic and inflammatory signaling pathways have been highlighted. Here, we discuss how selected diet-derived phytochemicals could alter the secretome signature as well as the crosstalk dynamics between the adipose tissue and the TME, with a focus on breast cancer. Their broader implication in the chemoprevention of obesity-related cancers is also discussed.

Decellularized extracellular matrix-based bioengineered 3D breast cancer scaffolds for personalized therapy and drug screening

Breast cancer (BC) is the second deadliest cancer after lung cancer. Similar to all cancers, it is also driven by a 3D microenvironment. The extracellular matrix (ECM) is an essential component of the 3D tumor micro-environment, wherein it functions as a scaffold for cells and provides metabolic support. BC is characterized by alterations in the ECM. Various studies have attempted to mimic BC-specific ECMs using artificial materials, such as Matrigel. Nevertheless, research has proven that naturally derived decellularized extracellular matrices (dECMs) are superior in providing the essential in vivo-like cues needed to mimic a cancer-like environment. Developing in vitro 3-D BC models is not straightforward and requires extensive analysis of the data established by researchers. For the benefit of researchers, in this review, we have tried to highlight all developmental studies that have been conducted by various scientists so far. The analysis of the conclusions drawn from these studies is also discussed. The advantages and drawbacks of the decellularization methods employed for generating BC scaffolds will be covered, and the review will shed light on how dECM scaffolds help develop a BC environment. The later stages of the article will also focus on immunogenicity issues arising from decellularization and the origin of the tissue. Finally, this review will also discuss the biofabrication of matrices, which is the core part of the bioengineering process.

Direct and cell-mediated EV-ECM interplay

Extracellular vesicles (EV) are a heterogeneous group of lipid particles excreted by cells. They play an important role in regeneration, development, inflammation, and cancer progression, together with the extracellular matrix (ECM), which they constantly interact with. In this review, we discuss direct and indirect interactions of EVs and the ECM and their impact on different physiological processes. The ECM affects the secretion of EVs, and the properties of the ECM and EVs modulate EVs' diffusion and adhesion. On the other hand, EVs can affect the ECM both directly through enzymes and indirectly through the modulation of the ECM synthesis and remodeling by cells. This review emphasizes recently discovered types of EVs bound to the ECM and isolated by enzymatic digestion, including matrix-bound nanovesicles (MBV) and tissue-derived EV (TiEV). In addition to the experimental studies, computer models of the EV-ECM-cell interactions, from all-atom models to quantitative pharmacology models aiming to improve our understanding of the interaction mechanisms, are also considered. STATEMENT OF SIGNIFICANCE: Application of extracellular vesicles in tissue engineering is an actively developing area. Vesicles not only affect cells themselves but also interact with the matrix and change it. The matrix also influences both cells and vesicles. In this review, different possible types of interactions between vesicles, matrix, and cells are discussed. Furthermore, the united EV-ECM system and its regulation through the cellular activity are presented.

Extracellular vesicle-mediated drug delivery in breast cancer theranostics

Breast cancer (BC) continues to be a significant global challenge due to drug resistance and severe side effects. The increasing prevalence is alarming, requiring new therapeutic approaches to address these challenges. At this point, Extracellular vesicles (EVs), specifically small endosome-released nanometer-sized EVs (SEVs) or exosomes, have been explored by literature as potential theranostics. Therefore, this review aims to highlight the therapeutic potential of exosomes in BC, focusing on their advantages in drug delivery and their ability to mitigate metastasis. Following the review, we identified exosomes' potential in combination therapies, serving as miRNA carriers and contributing to improved anti-tumor effects. This is evident in clinical trials investigating exosomes in BC, which have shown their ability to boost chemotherapy efficacy by delivering drugs like paclitaxel (PTX) and doxorubicin (DOX). However, the translation of EVs into BC therapy is hindered by various challenges. These challenges include the heterogeneity of EVs, the selection of the appropriate parent cell, the loading procedures, and determining the optimal administration routes. Despite the promising therapeutic potential of EVs, these obstacles must be addressed to realize their benefits in BC treatment.

Breast adipose tissue-derived extracellular vesicles from obese women alter tumor cell metabolism

Breast adipose tissue is an important contributor to the obesity-breast cancer link. Extracellular vesicles (EVs) are nanosized particles containing selective cargo, such as miRNAs, that act locally or circulate to distant sites to modulate target cell functions. Here, we find that long-term education of breast cancer cells with EVs obtained from breast adipose tissue of women who are overweight or obese (O-EVs) results in increased proliferation. RNA-seq analysis of O-EV-educated cells demonstrates increased expression of genes involved in oxidative phosphorylation, such as ATP synthase and NADH: ubiquinone oxidoreductase. O-EVs increase respiratory complex protein expression, mitochondrial density, and mitochondrial respiration in tumor cells. The mitochondrial complex I inhibitor metformin reverses O-EV-induced cell proliferation. Several miRNAs-miR-155-5p, miR-10a-3p, and miR-30a-3p-which promote mitochondrial respiration and proliferation, are enriched in O-EVs relative to EVs from lean women. O-EV-induced proliferation and mitochondrial activity are associated with stimulation of the Akt/mTOR/P70S6K pathway, and are reversed upon silencing of P70S6K. This study reveals a new facet of the obesity-breast cancer link with human breast adipose tissue-derived EVs causing metabolic reprogramming of breast cancer cells.

Advances in Therapeutic Applications of Extracellular Vesicles

Extracellular vesicles (EVs) are nanoscale bilayer phospholipid membrane vesicles released by cells. Contained large molecules such as nucleic acid, protein, and lipid, EVs are an integral part of cell communication. The contents of EVs vary based on the cell source and play an important role in both pathological and physiological conditions. EVs can be used as drugs or targets in disease treatment, and changes in the contents of EVs can indicate the progression of diseases. In recent years, with the continuous exploration of the structure, characteristics, and functions of EVs, the potential of engineered EVs for drug delivery and therapy being constantly explored. This review provides a brief overview of the structure, characteristics and functions of EVs, summarizes the advanced application of EVs and outlook on the prospect of it. It is our hope that this review will increase understanding of the current development of medical applications of EVs and help us overcome future challenges.

Breast adipose tissue-derived extracellular vesicles from women with obesity stimulate mitochondrial-induced dysregulated tumor cell metabolism

Breast adipose tissue is an important contributor to the obesity-breast cancer link. Dysregulated cell metabolism is now an accepted hallmark of cancer. Extracellular vesicles (EVs) are nanosized particles containing selective cargo, such as miRNAs, that act locally or circulate to distant sites to modulate target cell functions. Here, we found that long-term education of breast cancer cells (MCF7, T47D) with EVs from breast adipose tissue of women who are overweight or obese (O-EVs) leads to sustained increased proliferative potential. RNA-Seq of O-EV-educated cells demonstrates increased expression of genes, such as ATP synthase and NADH: ubiquinone oxidoreductase, involved in oxidative phosphorylation. O-EVs increase respiratory complex protein expression, mitochondrial density, and mitochondrial respiration in tumor cells. Mitochondrial complex I inhibitor, metformin, reverses O-EV-induced cell proliferation. Several miRNAs, miR-155-5p, miR-10a-3p, and miR-30a-3p, which promote mitochondrial respiration and proliferation, are enriched in O-EVs relative to EVs from lean women. O-EV-induced proliferation and mitochondrial activity are associated with stimulation of the Akt/mTOR/P70S6K pathway, and are reversed upon silencing of P70S6K. This study reveals a new facet of the obesity-breast cancer link with human breast adipose tissue-derived EVs causing the metabolic reprogramming of ER+ breast cancer cells.

ATP citrate lyase links increases in glycolysis to diminished release of vesicular suppressor of cytokine signaling 3 by alveolar macrophages

Extracellular vesicles (EVs) are important vectors for intercellular communication. Lung-resident alveolar macrophages (AMs) tonically secrete EVs containing suppressor of cytokine signaling 3 (SOCS3), a cytosolic protein that promotes homeostasis in the distal lung via its actions in recipient neighboring epithelial cells. AMs are metabolically distinct and exhibit low levels of glycolysis at steady state. To our knowledge, whether cellular metabolism influences the packaging and release of an EV cargo molecule has never been explored in any cellular context. Here, we report that increases in glycolysis following in vitro exposure of AMs to the growth and activating factor granulocyte-macrophage colony-stimulating factor inhibit the release of vesicular SOCS3 by primary AMs. Glycolytically diminished SOCS3 secretion requires export of citrate from the mitochondria to the cytosol and its subsequent conversion to acetyl-CoA by ATP citrate lyase. Our data for the first time implicate perturbations in intracellular metabolites in the regulation of vesicular cargo packaging and secretion.

Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells, Obesity and the Tumor Microenvironment of Breast Cancer

Breast cancer is the most frequently diagnosed cancer and a common cause of cancer-related death in women. It is well recognized that obesity is associated with an enhanced risk of more aggressive breast cancer as well as reduced patient survival. Adipose tissue is the major microenvironment of breast cancer. Obesity changes the composition, structure, and function of adipose tissue, which is associated with inflammation and metabolic dysfunction. Interestingly, adipose tissue is rich in ASCs/MSCs, and obesity alters the properties and functions of these cells. As a key component of the mammary stroma, ASCs play essential roles in the breast cancer microenvironment. The crosstalk between ASCs and breast cancer cells is multilateral and can occur both directly through cell-cell contact and indirectly via the secretome released by ASC/MSC, which is considered to be the main effector of their supportive, angiogenic, and immunomodulatory functions. In this narrative review, we aim to address the impact of obesity on ASCs/MSCs, summarize the current knowledge regarding the potential pathological roles of ASCs/MSCs in the development of breast cancer, discuss related molecular mechanisms, underline the possible clinical significance, and highlight related research perspectives. In particular, we underscore the roles of ASCs/MSCs in breast cancer cell progression, including proliferation and survival, angiogenesis, migration and invasion, the epithelial-mesenchymal transition, cancer stem cell development, immune evasion, therapy resistance, and the potential impact of breast cancer cells on ASCS/MSCs by educating them to become cancer-associated fibroblasts. We conclude that ASCs/MSCs, especially obese ASCs/MSCs, may be key players in the breast cancer microenvironment. Targeting these cells may provide a new path of effective breast cancer treatment.

Exosomes in Breast Cancer: Involvement in Tumor Dissemination and Prospects for Liquid Biopsy

In women, breast cancer (BC) is the most commonly diagnosed cancer (24.5%) and the leading cause of cancer death (15.5%). Understanding how this heterogeneous disease develops and the confirm mechanisms behind tumor progression is of utmost importance. Exosomes are long-range message vesicles that mediate communication between cells in physiological conditions but also in pathology, such as breast cancer. In recent years, there has been an exponential rise in the scientific studies reporting the change in morphology and cargo of tumor-derived exosomes. Due to the transfer of biologically active molecules, such as RNA (microRNA, long non-coding RNA, mRNA, etc.) and proteins (transcription factors, enzymes, etc.) into recipient cells, these lipid bilayer 30-150 nm vesicles activate numerous signaling pathways that promote tumor development. In this review, we attempt to shed light on exosomes' involvement in breast cancer pathogenesis (including epithelial-to-mesenchymal transition (EMT), tumor cell proliferation and motility, metastatic processes, angiogenesis stimulation, and immune system repression). Moreover, the potential use of exosomes as promising diagnostic biomarkers for liquid biopsy of breast cancer is also discussed.

Cancer-Associated Exosomal CBFB Facilitates the Aggressive Phenotype, Evasion of Oxidative Stress, and Preferential Predisposition to Bone Prometastatic Factor of Breast Cancer Progression

Background. Despite therapeutic advancements, metastasis remains a major cause in breast cancer-specific mortality. Breast cancer cells are susceptible to oxidative damage and exhibit high levels of oxidative stress, including protein damage, DNA damage, and lipid peroxidation. Some breast cancer risk factors may change the level of endogenous oxidative stress. Circulating exosomes play critical roles in tumorigenesis, distant metastasis, and poor prognosis in patients with breast cancer. Methods. We used an online database to analyze the expression and prognostic value of core binding factor subunit β (CBFB) and oxidative stress–related targets in patients with breast cancer. Serum from healthy controls and patients with primary breast cancer or bone metastatic breast cancer in the bone was collected. Exosomes were isolated from the sera or cell culture media. We used an MDA-MB-436-innoculated tumor xenograft mouse model for silencing CBFB. Results. Circulating exosomes from patients with breast cancer metastasis to the bone were rich in CBFB. The human mammary fibroblast cells HMF3A and fibroblasts derived from patient samples cocultured with exosomes had increased α-SMA and vimentin expression and IL-6 and OPN secretion. Similarly, nonmetastatic breast cancer cells cocultured with exosomes exhibited increased levels of certain markers, including vimentin, snail1, CXCR4, and Runx2, and the exosomes had high CBFB expression. Silencing CBFB in metastatic MDA-MB-436 and MDA-MB-157 cells resulted in suppressed migration and invasion and downregulation of vimentin, CXCR4, snail1, Runx2, CD44, and OPN. Conversely, CBFB overexpression resulted in upregulation of Runx2, vimentin, snail1, CD44, and OPN in nonmetastatic T47D and MCF12A cells. The CBFB-rich exosomes derived from MDA-MB-436 cells induced enhanced metastatic phenotypes in the low-metastatic T47D and MCF12A cell lines. Conclusion. Our results revealed that CBFB may promote bone metastasis in patients with breast cancer. Of therapeutic relevance, targeting CBFB resulted in decreased tumor burden and bone metastasis, downregulation of bone metastasis markers, and impaired regulation of oxidative stress–related proteins NAE1 and NOS1.

Peripheral Nerve Decellularization for In Vitro Extracellular Matrix Hydrogel Use: A Comparative Study

The rise of tissue-engineered biomaterials has introduced more clinically translatable models of disease, including three-dimensional (3D) decellularized extracellular matrix (dECM) hydrogels. Specifically, decellularized nerve hydrogels have been utilized to model peripheral nerve injuries and disorders in vitro; however, there lacks standardization in decellularization methods. Here, rat sciatic nerves of varying preparations were decellularized using previously established methods: sodium deoxycholate (SD)-based, 3-((3-cholamidopropyl)dimethylammonio)-1-propanesulfonate (CHAPS)-based, and apoptosis-mediated. These nerves were characterized for cellular debris removal, ECM retention, and low cytotoxicity with cultured Schwann cells. The best preparations of each decellularization method were digested into dECM hydrogels, and rheological characterization, gelation kinetics, and confocal reflectance imaging of collagen fibril assembly were performed. It was determined that the SD-based method with nerve epineurial removal best maintained the overall ECM composition and mechanical properties of physiological peripheral nerves while efficiently stripping the scaffolds of tissue-specific cells and debris. This method was then utilized as a culture platform for quiescent Schwann cells and cancer-nerve crosstalk. Hydrogel-embedded Schwann cells were found to have high viability and act in a more physiologically relevant manner than those cultured in monolayers, and the hydrogel platform allowed for the activation of Schwann cells following treatment with cancer secreted factors. These findings establish a standard for peripheral nerve decellularization for usage as a dECM hydrogel testbed for in vitro peripheral nerve disease modeling and may facilitate the development of treatments for peripheral nerve disease and injury.

TIMP-1-expressing breast tumor spheroids for the evaluation of drug penetration and efficacy

Abundance of stromal cells and extracellular matrix (ECM) is observed in breast cancer, acting as a barrier for drug penetration and presenting a key issue for developing efficient therapeutics. In this study, we aimed to develop a three-dimensional (3D) multicellular tumor model comprising cancer and stromal cells that could effectively mimic the drug resistance properties of breast cancer. Three different types of spheroid models were designed by co-culturing breast cancer cells (MDA-MB-231) with three different types of stromal cells: human adipose-derived stromal cells (hASCs), human bone marrow stromal cells, or human dermal fibroblasts. Compared with other models, in the hASC co-culture model, tissue inhibitor of metalloproteinases-1 (TIMP-1) was highly expressed and the activity of matrix metalloproteinases was decreased, resulting in a higher ECM deposition on the spheroid surfaces. This spheroid model showed less drug penetration and treatment efficacy than the other models. TIMP-1 silencing in hASCs reduced ECM protein expression and increased drug penetration and vulnerability. A quantitative structure-activity relationship study using multiple linear regression drew linear relationships between the chemical properties of drugs and experimentally determined permeability values. Drugs that did not match the drug-likeness rules exhibited lower permeability in the 3D tumor model. Taken together, our findings indicate that this 3D multicellular tumor model may be used as a reliable platform for efficiently screening therapeutics agents for solid tumors.

Extracellular Vesicles and Transforming Growth Factor β Signaling in Cancer

Complexity in mechanisms that drive cancer development and progression is exemplified by the transforming growth factor β (TGF-β) signaling pathway, which suppresses early-stage hyperplasia, yet assists aggressive tumors to achieve metastasis. Of note, several molecules, including mRNAs, non-coding RNAs, and proteins known to be associated with the TGF-β pathway have been reported as constituents in the cargo of extracellular vesicles (EVs). EVs are secreted vesicles delimited by a lipid bilayer and play critical functions in intercellular communication, including regulation of the tumor microenvironment and cancer development. Thus, this review aims at summarizing the impact of EVs on TGF-β signaling by focusing on mechanisms by which EV cargo can influence tumorigenesis, metastatic spread, immune evasion and response to anti-cancer treatment. Moreover, we emphasize the potential of TGF-β-related molecules present in circulating EVs as useful biomarkers of prognosis, diagnosis, and prediction of response to treatment in cancer patients.

Dual Mode Sensing of Binding and Blocking of Cancer Exosomes to Biomimetic Human Primary Stem Cell Surfaces

Cancer-derived exosomes (cEXOs) facilitate transfer of information between tumor and human primary stromal cells, favoring cancer progression. Although the mechanisms used during this information exchange are still not completely understood, it is known that binding is the initial contact established between cEXOs and cells. Hence, studying binding and finding strategies to block it are of great therapeutic value. However, such studies are challenging for a variety of reasons, including the need for human primary cell culture, the difficulty in decoupling and isolating binding from internalization and cargo delivery, and the lack of techniques to detect these specific interactions. In this work, we created a supported biomimetic stem cell membrane incorporating membrane components from human primary adipose-derived stem cells (ADSCs). We formed the supported membrane on glass and on multielectrode arrays to offer the dual option of optical or electrical detection of cEXO binding to the membrane surface. Using our platform, we show that cEXOs bind to the stem cell membrane and that binding is blocked when an antibody to integrin β1, a component of ADSC surface, is exposed to the membrane surface prior to cEXOs. To test the biological outcome of blocking this interaction, we first confirm that adding cEXOs to cultured ADSCs leads to the upregulation of vascular endothelial growth factor, a measure of proangiogenic activity. Next, when ADSCs are first blocked with anti-integrin β1 and then exposed to cEXOs, the upregulation of proangiogenic activity and cell proliferation are significantly reduced. This biomimetic membrane platform is the first cell-free label-free in vitro platform for the recapitulation and study of cEXO binding to human primary stem cells with potential for therapeutic molecule screening as it is compatible with scale-up and multiplexing.

IFIT3 (interferon induced protein with tetratricopeptide repeats 3) modulates STAT1 expression in small extracellular vesicles

We have previously shown that the αvβ6 integrin plays a key role in promoting prostate cancer (PrCa) and it can be transferred to recipient cells via small extracellular vesicles (sEVs). Furthermore, we have reported in a proteomic analysis that αvβ6 integrin down-regulation increases the expression of IFIT3 (interferon induced protein with tetratricopeptide repeats 3) in PrCa cells and their derived sEVs. IFIT3 is a protein well known for being an antiviral effector, but recently its role in cancer has also been elucidated. To study the relationship between IFIT3 and STAT1 (signal transducer and activator of transcription 1), an upstream regulator of IFIT3, in PrCa cells and their released sEVs, we used CRISPR/Cas9 techniques to down-regulate the expression of the β6 integrin subunit, IFIT3 or STAT1. Our results show that IFIT3 and STAT1 are highly expressed in PrCa cells devoid of the β6 integrin subunit. However, IFIT3 but not STAT1, is present in sEVs derived from PrCa cells lacking the β6 integrin subunit. We demonstrate that loss of IFIT3 generates sEVs enriched in STAT1 but reduces the levels of STAT1 in the cells. As expected, IFIT3 is not detectable in STAT1 negative cells or sEVs. We thus propose that the observed STAT1 enrichment in sEVs is a compensatory mechanism for the loss of IFIT3. Overall, these results provide new insights into the intrinsic role of IFIT3 as a regulator of STAT1 expression in sEVs and in intercellular communication in PrCa.

Adipose-Derived Stem Cell: "Treat or Trick"

Stem cells have been widely used for treating disease due to the various benefits they offer in the curing process. Several treatments using stem cells have undergone clinical trials, such as cell-based therapies for heart disease, sickle cell disease, thalassemia, etc. Adipose-derived stem cells are some of the many mesenchymal stem cells that exist in our body that can be harvested from the abdomen, thighs, etc. Adipose tissue is easy to harvest, and its stem cells can be obtained in higher volumes compared to stem cells harvested from bone marrow, for which a more invasive technique is required with a smaller volume obtained. Many scientists have expressed interest in investigating the role of adipose-derived stem cells in treating disease since their use was first described. This is due to these stem cells' ability to differentiate into multiple lineages and secrete a variety of growth factors and proteins. Previous studies have found that the hormones, cytokines, and growth factors contained in adipose tissue play major roles in the metabolic regulation of adipose tissue, as well as in energy balance and whole-body homeostasis through their endocrine, autocrine, and paracrine functions. These are thought to be important contributors to the process of tissue repair and regeneration. However, it remains unclear how effective and safe ADSCs are in treating diseases. The research that has been carried out to date is in order to investigate the impact of ADSCs in disease treatment, as described in this review, to highlight its "trick or treat" effect in medical treatment.

The Neglected Liaison: Targeting Cancer Cell Metabolic Reprogramming Modifies the Composition of Non-Malignant Populations of the Tumor Microenvironment

Metabolic reprogramming is a well-known hallmark of cancer, whereby the development of drugs that target cancer cell metabolism is gaining momentum. However, when establishing preclinical studies and clinical trials, it is often neglected that a tumor mass is a complex system in which cancer cells coexist and interact with several types of microenvironment populations, including endothelial cells, fibroblasts and immune cells. We are just starting to understand how such populations are affected by the metabolic changes occurring in a transformed cell and little is known about the impact of metabolism-targeting drugs on the non-malignant tumor components. Here we provide a general overview of the links between cancer cell metabolism and tumor microenvironment (TME), particularly focusing on the emerging literature reporting TME-specific effects of metabolic therapies.

Extracellular Vesicles in Airway Homeostasis and Pathophysiology

The epithelial–mesenchymal trophic unit (EMTU) is a morphofunctional entity involved in the maintenance of the homeostasis of airways as well as in the pathogenesis of several diseases, including asthma and chronic obstructive pulmonary disease (COPD). The “muco-microbiotic layer” (MML) is the innermost layer of airways made by microbiota elements (bacteria, viruses, archaea and fungi) and the surrounding mucous matrix. The MML homeostasis is also crucial for maintaining the healthy status of organs and its alteration is at the basis of airway disorders. Nanovesicles produced by EMTU and MML elements are probably the most important tool of communication among the different cell types, including inflammatory ones. How nanovesicles produced by EMTU and MML may affect the airway integrity, leading to the onset of asthma and COPD, as well as their putative use in therapy will be discussed here.

Extracellular Vesicles: Novel Opportunities to Understand and Detect Neoplastic Diseases

With a size range from 30 to 1000 nm, extracellular vesicles (EVs) are one of the smallest cell components able to transport biologically active molecules. They mediate intercellular communications and play a fundamental role in the maintenance of tissue homeostasis and pathogenesis in several types of diseases. In particular, EVs actively contribute to cancer initiation and progression, and there is emerging understanding of their role in creation of the metastatic niche. This fact underlies the recent exponential growth in EV research, which has improved our understanding of their specific roles in disease and their potential applications in diagnosis and therapy. EVs and their biomolecular cargo reflect the state of the diseased donor cells, and can be detected in body fluids and exploited as biomarkers in cancer and other diseases. Relatively few studies have been published on EVs in the veterinary field. This review provides an overview of the features and biology of EVs as well as recent developments in EV research including techniques for isolation and analysis, and will address the way in which the EVs released by diseased tissues can be studied and exploited in the field of veterinary pathology. Uniquely, this review emphasizes the important contribution that pathologists can make to the field of EV research: pathologists can help EV scientists in studying and confirming the role of EVs and their molecular cargo in diseased tissues and as biomarkers in liquid biopsies.

Obesity-associated Adipose Stromal Cells Promote Breast Cancer Invasion Through Direct Cell Contact and ECM Remodeling

Obesity increases the risk and worsens the prognosis for breast cancer due, in part, to altered adipose stromal cell (ASC) behavior. Whether ASCs from obese individuals increase migration of breast cancer cells relative to their lean counterparts, however, remains unclear. To test this connection, multicellular spheroids composed of MCF10A-derived tumor cell lines of varying malignant potential and lean or obese ASCs were embedded into collagen scaffolds mimicking the elastic moduli of interstitial breast adipose tissue. Confocal image analysis suggests that tumor cells alone migrate insignificantly under these conditions. However, direct cell-cell contact with either lean or obese ASCs enables them to migrate collectively, whereby obese ASCs activate tumor cell migration more effectively than their lean counterparts. Time-resolved optical coherence tomography (OCT) imaging suggests that obese ASCs facilitate tumor cell migration by mediating contraction of local collagen fibers. Matrix metalloproteinase (MMP)-dependent proteolytic activity significantly contributes to ASC-mediated tumor cell invasion and collagen deformation. However, ASC contractility is also important, as co-inhibition of both MMPs and contractility is necessary to completely abrogate ASC-mediated tumor cell migration. These findings imply that obesity-mediated changes of ASC phenotype may impact tumor cell migration and invasion with potential implications for breast cancer malignancy in obese patients.

The Extracellular Matrix and Vesicles Modulate the Breast Tumor Microenvironment

Emerging evidence has shown multiple roles of the tumor microenvironment (TME) components, specifically the extracellular matrix (ECM), in breast cancer development, progression, and metastasis. Aside from the biophysical properties and biochemical composition of the breast ECM, the signaling molecules are extremely important in maintaining homeostasis, and in the breast TME, they serve as the key components that facilitate tumor progression and immune evasion. Extracellular vesicles (EVs), the mediators that convey messages between the cells and their microenvironment through signaling molecules, have just started to capture attention in breast cancer research. In this comprehensive review, we first provide an overview of the impact of ECM in breast cancer progression as well as the alterations occurring in the TME during this process. The critical importance of EVs and their biomolecular contents in breast cancer progression and metastasis are also discussed. Finally, we discuss the potential biomedical or clinical applications of these extracellular components, as well as how they impact treatment outcomes.

Extracellular Vesicles-Based Drug Delivery Systems: A New Challenge and the Exemplum of Malignant Pleural Mesothelioma

Research for the most selective drug delivery to tumors represents a fascinating key target in science. Alongside the artificial delivery systems identified in the last decades (e.g., liposomes), a family of natural extracellular vesicles (EVs) has gained increasing focus for their potential use in delivering anticancer compounds. EVs are released by all cell types to mediate cell-to-cell communication both at the paracrine and the systemic levels, suggesting a role for them as an ideal nano-delivery system. Malignant pleural mesothelioma (MPM) stands out among currently untreatable tumors, also due to the difficulties in achieving an early diagnosis. Thus, early diagnosis and treatment of MPM are both unmet clinical needs. This review looks at indirect and direct evidence that EVs may represent both a new tool for allowing an early diagnosis of MPM and a potential new delivery system for more efficient therapeutic strategies. Since MPM is a relatively rare malignant tumor and preclinical MPM models developed to date are very few and not reliable, this review will report data obtained in other tumor types, suggesting the potential use of EVs in mesothelioma patients as well.

Supported Membrane Platform to Assess Surface Interactions between Extracellular Vesicles and Stromal Cells

Extracellular vesicles (EVs) are membrane-encapsulated particles secreted by eukaryotic cells that stimulate cell communication and horizontal cargo exchange. EV interactions with stromal cells can result in molecular changes in the recipient cell and, in some cases, lead to disease progression. However, mechanisms leading to these changes are poorly understood. A few model systems are available for studying the outcomes of surface interactions between EV membranes with stromal cells. Here, we created a hybrid supported bilayer incorporating EVs membrane material, called an extracellular vesicle supported bilayer, EVSB. Using EVSBs, we investigated the surface interactions between breast cancer EVs and adipose-derived stem cells (ADSCs) by culturing ADSCs on EVSBs and analyzing cell adhesion, spreading, viability, vascular endothelial growth factor (VEGF) secretion, and myofibroblast differentiation. Results show that cell viability, adhesion, spreading, and proangiogenic activity were enhanced, conditions that promote oncogenic activity, but cell differentiation was not. This model system could be used to develop therapeutic strategies to limit EV-ADSC interactions and proangiogenic conditions. Finally, this model system is not limited to the study of cancer but can be used to study surface interactions between EVs from any origin and any target cell to investigate EV mechanisms leading to cellular changes in other diseases.

The Role of Dysfunctional Adipose Tissue in Pancreatic Cancer: A Molecular Perspective

Pancreatic cancer (PC) is a lethal malignancy with rising incidence and limited therapeutic options. Obesity is a well-established risk factor for PC development. Moreover, it negatively affects outcome in PC patients. Excessive fat accumulation in obese, over- and normal-weight individuals induces metabolic and inflammatory changes of adipose tissue microenvironment leading to a dysfunctional adipose “organ”. This may drive the association between abnormal fat accumulation and pancreatic cancer. In this review, we describe several molecular mechanisms that underpin this association at both local and systemic levels. We focus on the role of adipose tissue-derived circulating factors including adipokines, hormones and pro-inflammatory cytokines, as well as on the impact of the local adipose tissue in promoting PC. A discussion on potential therapeutic interventions, interfering with pro-tumorigenic effects of dysfunctional adipose tissue in PC, is included. Considering the raise of global obesity, research efforts to uncover the molecular basis of the relationship between pancreatic cancer and adipose tissue dysfunction may provide novel insights for the prevention of this deadly disease. In addition, these efforts may uncover novel targets for personalized interventional strategies aimed at improving the currently unsatisfactory PC therapeutic options.

Collagen microarchitecture mechanically controls myofibroblast differentiation

Altered microarchitecture of collagen type I is a hallmark of wound healing and cancer that is commonly attributed to myofibroblasts. However, it remains unknown which effect collagen microarchitecture has on myofibroblast differentiation. Here, we combined experimental and computational approaches to investigate the hypothesis that the microarchitecture of fibrillar collagen networks mechanically regulates myofibroblast differentiation of adipose stromal cells (ASCs) independent of bulk stiffness. Collagen gels with controlled fiber thickness and pore size were microfabricated by adjusting the gelation temperature while keeping their concentration constant. Rheological characterization and simulation data indicated that networks with thicker fibers and larger pores exhibited increased strain-stiffening relative to networks with thinner fibers and smaller pores. Accordingly, ASCs cultured in scaffolds with thicker fibers were more contractile, expressed myofibroblast markers, and deposited more extended fibronectin fibers. Consistent with elevated myofibroblast differentiation, ASCs in scaffolds with thicker fibers exhibited a more proangiogenic phenotype that promoted endothelial sprouting in a contractility-dependent manner. Our findings suggest that changes of collagen microarchitecture regulate myofibroblast differentiation and fibrosis independent of collagen quantity and bulk stiffness by locally modulating cellular mechanosignaling. These findings have implications for regenerative medicine and anticancer treatments.

The Role of Metabolic Changes in Shaping the Fate of Cancer-Associated Adipose Stem Cells

Adipose tissue in physiological and in metabolically altered conditions (obesity, diabetes, metabolic syndrome) strictly interacts with the developing tumors both systemically and locally. In addition to the cancer-associated fibroblasts, adipose cells have also recently been described among the pivotal actors of the tumor microenvironment responsible for sustaining tumor development and progression. In particular, emerging evidence suggests that not only the mature adipocytes but also the adipose stem cells (ASCs) are able to establish a strict crosstalk with the tumour cells, thus resulting in a reciprocal reprogramming of both the tumor and adipose components. This review will focus on the metabolic changes induced by this interaction as a driver of fate determination occurring in cancer-associated ASCs (CA-ASCs) to support the tumor metabolic requirements. We will showcase the major role played by the metabolic changes occurring in the adipose tumor microenvironment that regulates ASC fate and consequently cancer progression. Our new results will also highlight the CA-ASC response in vitro by using a coculture system of primary ASCs grown with cancer cells originating from two different types of adrenal cancers [adrenocortical carcinoma (ACC) and pheochromocytoma]. In conclusion, the different factors involved in this crosstalk process will be analyzed and their effects on the adipocyte differentiation potential and functions of CA-ASCs will be discussed.

Unraveling Adipocytes and Cancer Links: Is There a Role for Senescence?

Senescence is characterized by a permanent cell cycle arrest that is elicited in response to different stresses. In addition, senescent cells undergo multiple other phenotypic alterations, such as autophagy modulation, metabolic reprogramming, and the senescence-associated secretory phenotype (SASP). These senescence-related and inflammatory effects prevail within tumors and are strongly controlled by cancer properties, and inflammatory mediators further maintain and propagate the senescence process to adjacent cells. It is important to consider these detrimental effects that may drive tumorigenesis or cancer relapse. Importantly, cancer-associated adipocytes (CAAs) are one of the primary stromal cells in various tumor microenvironments and favor tumor progression by releasing various factors that can mediate local and systemic effects. However, it remains unclear whether CAAs possess senescent features. In this review, we discuss the complex relationship between senescence and CAAs and highlight important considerations for therapeutics.

Extracellular Vesicles as Signaling Mediators and Disease Biomarkers across Biological Barriers

Extracellular vesicles act as shuttle vectors or signal transducers that can deliver specific biological information and have progressively emerged as key regulators of organized communities of cells within multicellular organisms in health and disease. Here, we survey the evolutionary origin, general characteristics, and biological significance of extracellular vesicles as mediators of intercellular signaling, discuss the various subtypes of extracellular vesicles thus far described and the principal methodological approaches to their study, and review the role of extracellular vesicles in tumorigenesis, immunity, non-synaptic neural communication, vascular-neural communication through the blood-brain barrier, renal pathophysiology, and embryo-fetal/maternal communication through the placenta.

Adipose Tumor Microenvironment

The term "adipose tissue" represents a multicellular and multifunctional organ involved in lipid storage, in hormone and temperature regulation, and in the protection of bones and vital organs from impact-based damage. Emerging evidence now suggests a more malignant role of adipose tissue in promoting cancer onset and progression via the release of secreted factors such as interleukin-6 (IL6) and extracellular vesicles (EVs). These adipose-source factors subsequently affect various aspects of tumorigenesis and/or cancer progression by either directly enhancing the tumor cell oncogenic phenotype or indirectly by the stimulating adjacent normal cells to adopt a more pro-cancer phenotype. Due to the recent growing interest in the role of IL6 and EVs released by adipose tissue in cancer promotion and progression, we are focusing on the protumorigenic impact of fat tissue via IL6 and EV secretion.

The role of tumor-derived exosomes in tumor angiogenesis and tumor progression

Exosomes, belonging to the group of extracellular bodies, are released by healthy as well as cancerous cells and serve as a communication pathway. Tumor-derived exosomes (TEX) possess the capacity to reprogram the function of normal cells owing to their genetic and molecular cargo. Such exosomes target endothelial cells (among others) in the tumor microenvironment to promote angiogenesis. Blood supply is essential in solid tumor growth and metastasis. The potential of pro-angiogenic changes is enhanced by an increased amount of circulating tumor-derived exosomes in the body fluids of cancer patients. A vascular network is important, since the proliferation, as well as the metastatic spread of cancer cells depends on an adequate supply of oxygen and nutrients, and the removal of waste products. New blood vessels and lymphatic vessels are formed through processes called angiogenesis and lymphangiogenesis, respectively. Angiogenesis is regulated by both activator and inhibitor molecules. Thousands of patients have received anti-angiogenic therapy to date. Despite their theoretical efficacy, anti-angiogenic treatments have not proved beneficial in terms of long-term survival. Tumor-derived exosomes carrying pro-angiogenic factors might be a target for new anti-cancer therapy.

Impact of the Different Preparation Methods to Obtain Human Adipose-Derived Stromal Vascular Fraction Cells (AD-SVFs) and Human Adipose-Derived Mesenchymal Stem Cells (AD-MSCs): Enzymatic Digestion Versus Mechanical Centrifugation

Autologous therapies using adipose-derived stromal vascular fraction (AD-SVFs) and adult adipose-derived mesenchymal stem cells (AD-MSCs) warrant careful preparation of the harvested adipose tissue. Currently, no standardized technique for this preparation exists. Processing quantitative standards (PQSs) define manufacturing quantitative variables (such as time, volume, and pressure). Processing qualitative standards (PQLSs) define the quality of the materials and methods in manufacturing. The purpose of the review was to use PQSs and PQLSs to report the in vivo and in vitro results obtained by different processing kits that use different procedures (enzymatic vs. non-enzymatic) to isolate human AD-SVFs/AD-MSCs. PQSs included the volume of fat tissue harvested and reagents used, the time/gravity of centrifugation, and the time, temperature, and tilt level/speed of incubation and/or centrifugation. PQLSs included the use of a collagenase, a processing time of 30 min, kit weight, transparency of the kit components, the maintenance of a closed sterile processing environment, and the use of a small centrifuge and incubating rocker. Using a kit with the PQSs and PQLSs described in this study enables the isolation of AD-MSCs that meet the consensus quality criteria. As the discovery of new critical quality attributes (CQAs) of AD-MSCs evolve with respect to purity and potency, adjustments to these benchmark PQSs and PQLs will hopefully isolate AD-MSCs of various CQAs with greater reproducibility, quality, and safety. Confirmatory studies will no doubt need to be completed.

Adipose-Derived Stem Cells in Cancer Progression: New Perspectives and Opportunities

Growing importance has been attributed to interactions between tumors, the stromal microenvironment and adult mesenchymal stem cells. Adipose-derived stem cells (ASCs) are routinely employed in regenerative medicine and in autologous fat transfer procedures. To date, clinical trials have failed to demonstrate the potential pro-oncogenic role of ASC enrichment. Nevertheless, some pre-clinical studies from in vitro and in vivo models have suggested that ASCs act as a potential tumor promoter for different cancer cell types, and support tumor progression and invasiveness through the activation of several intracellular signals. Interaction with the tumor microenvironment and extracellular matrix remodeling, the exosomal release of pro-oncogenic factors as well as the induction of epithelial-mesenchymal transitions are the most investigated mechanisms. Moreover, ASCs have also demonstrated an elective tumor homing capacity and this tumor-targeting capacity makes them a suitable carrier for anti-cancer drug delivery. New genetic and applied nanotechnologies may help to design promising anti-cancer cell-based approaches through the release of loaded intracellular nanoparticles. These new anti-cancer therapies can more effectively target tumor cells, reaching higher local concentrations even in pharmacological sanctuaries, and thus minimizing systemic adverse drug effects. The potential interplay between ASCs and tumors and potential ASCs-based therapeutic approaches are discussed.

Differential roles of VEGF: Relevance to tissue fibrosis

Excessive extracellular matrix deposition and pathological vascularization are characteristics of fibrosis, which compromises the normal functioning of organs. Although whether angiogenesis can be induced and can occur in parallel with the progression of fibrosis has not been definitely determined, angiogenesis undoubtedly plays a vital role in fibrosis. Since vascular endothelial growth factor (VEGF) is one of the most effective proangiogenic factors, VEGF-targeting interventions have been a focus for the development of therapeutic strategies against fibrosis. In this review, we will summarize the current knowledge of the role of VEGF and its relevant mechanisms in fibrotic biology. We especially expect to provide a comprehensive overview of the therapeutic potential of VEGF-targeted therapy strategies to restore vascular function in the organs affected by fibrosis.

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.

Concise Review: Adipose-Derived Stem Cells (ASCs) and Adipocyte-Secreted Exosomal microRNA (A-SE-miR) Modulate Cancer Growth and proMote Wound Repair

Adipose-derived stem cells (ASCs) have been routinely used from several years in regenerative surgery without any definitive statement about their potential pro-oncogenic or anti-oncogenic role. ASCs has proven to favor tumor progression in several experimental cancer models, playing a central role in regulating tumor invasiveness and metastatic potential through several mechanisms, such as the paracrine release of exosomes containing pro-oncogenic molecules and the induction of epithelial-mesenchymal transition. However, the high secretory activity and the preferential tumor-targeting make also ASCs a potentially suitable vehicle for delivery of new anti-cancer molecules in tumor microenvironment. Nanotechnologies, viral vectors, drug-loaded exosomes, and micro-RNAs (MiR) represent additional new tools that can be applied for cell-mediated drug delivery in a tumor microenvironment. Recent studies revealed that the MiR play important roles in paracrine actions on adipose-resident macrophages, and their dysregulation has been implicated in the pathogenesis of obesity, diabetes, and diabetic complications as wounds. Numerous MiR are present in adipose tissues, actively participating in the regulation of adipogenesis, adipokine secretion, inflammation, and inter-cellular communications in the local tissues. These results provide important insights into Adipocyte-secreted exosomal microRNA (A-SE-MiR) function and they suggest evaluating the potential role of A-SE-MiR in tumor progression, the mechanisms underlying ASCs-cancer cell interplay and clinical safety of ASCs-based therapies.

The obese adipose tissue microenvironment in cancer development and progression

Obesity is associated with both increased cancer incidence and progression in multiple tumour types, and is estimated to contribute to up to 20% of cancer-related deaths. These associations are driven, in part, by metabolic and inflammatory changes in adipose tissue that disrupt physiological homeostasis both within local tissues and systemically. However, the mechanisms underlying the obesity-cancer relationship are poorly understood. In this Review, we describe how the adipose tissue microenvironment (ATME) evolves during body-weight gain, and how these changes might influence tumour initiation and progression. We focus on multiple facets of ATME physiology, including inflammation, vascularity and fibrosis, and discuss therapeutic interventions that have the potential to normalize the ATME, which might be translationally relevant for cancer prevention and therapy. Given that the prevalence of obesity is increasing on an international scale, translational research initiatives are urgently needed to provide mechanistic explanations for the obesity-cancer relationship, and how to best identify high-risk individuals without relying on crude measures, such as BMI.

The great escape: How metastases of melanoma, and other carcinomas, avoid elimination

IMPACT STATEMENT

Cancers kill mainly because metastatic disease is resistant to systemic therapies. It was hoped that newer targeted and immunomodulatory interventions could overcome these issues. However, recent findings point to a generalized resistance to elimination imparted by both cancer-intrinsic and -extrinsic changes to provide survival advantages to the disseminated tumor cells. Here, we present a novel conceptual framework for the microenvironmental inputs and changes that contribute to this generalized therapeutic resistance. In addition we address the issues of experimental systems in terms of studying this phenomenon with their advantages and limitations. This is meant to spur studies into this critical aspect of tumor progression that directly leads to cancer mortality.

The Crosstalk between Cancer Stem Cells and Microenvironment Is Critical for Solid Tumor Progression: The Significant Contribution of Extracellular Vesicles

Several evidences nowadays demonstrated the critical role of the microenvironment in regulating cancer stem cells and their involvement in tumor progression. Extracellular vesicles (EVs) are considered as one of the most effective vehicles of information among cells. Accordingly, a number of studies led to the recognition of stem cell-associated EVs as new complexes able to contribute to cell fate determination of either normal or tumor cells. In this review, we aim to highlight an existing bidirectional role of EV-mediated communication—from cancer stem cells to microenvironment and also from microenvironment to cancer stem cells—in the most widespread solid cancers as prostate, breast, lung, and colon tumors.

Extracellular Vesicles and Matrix Remodeling Enzymes: The Emerging Roles in Extracellular Matrix Remodeling, Progression of Diseases and Tissue Repair

Extracellular vesicles (EVs) are membrane enclosed micro- and nano-sized vesicles that are secreted from almost every species, ranging from prokaryotes to eukaryotes, and from almost every cell type studied so far. EVs contain repertoire of bioactive molecules such as proteins (including enzymes and transcriptional factors), lipids, carbohydrates and nucleic acids including DNA, coding and non-coding RNAs. The secreted EVs are taken up by neighboring cells where they release their content in recipient cells, or can sail through body fluids to reach distant organs. Since EVs transport bioactive cargo between cells, they have emerged as novel mediators of extra- and intercellular activities in local microenvironment and inter-organ communications distantly. Herein, we review the activities of EV-associated matrix-remodeling enzymes such as matrix metalloproteinases, heparanases, hyaluronidases, aggrecanases, and their regulators such as extracellular matrix metalloproteinase inducers and tissue inhibitors of metalloproteinases as novel means of matrix remodeling in physiological and pathological conditions. We discuss how such EVs act as novel mediators of extracellular matrix degradation to prepare a permissive environment for various pathological conditions such as cancer, cardiovascular diseases, arthritis and metabolic diseases. Additionally, the roles of EV-mediated matrix remodeling in tissue repair and their potential applications as organ therapies have been reviewed. Collectively, this knowledge could benefit the development of new approaches for tissue engineering.

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

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

Extracellular vesicles: important collaborators in cancer progression

Extracellular vesicles (EVs) are membrane vesicles that are released from cells and mediate cell-cell communication. EVs carry protein, lipid, and nucleic acid cargoes that interact with recipient cells to alter their phenotypes. Evidence is accumulating that tumor-derived EVs can play important roles in all steps of cancer progression. Here, we review recent studies reporting critical roles for EVs in four major areas of cancer progression: promotion of cancer invasiveness and motility, enhancement of angiogenesis and vessel permeability, conditioning premetastatic niches, and immune suppression.

Roles of Extracellular Vesicles in Metastatic Breast Cancer

Cells can secrete extracellular vesicles (EVs) to communicate with neighboring or distant cells by EVs which are composed of a lipid bilayer containing transmembrane proteins and enclosing cytosolic proteins, lipids, and nucleic acids. Breast Cancer is the most frequently diagnosed malignancy with more than 1 million new cases each year and ranks the leading cause of cancer mortality in women worldwide. In this review, we will discuss recent progresses of the roles and mechanisms of cancer-derived EVs in metastatic breast cancer, with a special attention on tumor microenvironment construction, progression, and chemo/radiotherapy responses. This review also covers EV roles as biomarker and therapeutic target in clinical application.

Exosomal αvβ6 integrin is required for monocyte M2 polarization in prostate cancer

Therapeutic approaches aimed at curing prostate cancer are only partially successful given the occurrence of highly metastatic resistant phenotypes that frequently develop in response to therapies. Recently, we have described αvβ6, a surface receptor of the integrin family as a novel therapeutic target for prostate cancer; this epithelial-specific molecule is an ideal target since, unlike other integrins, it is found in different types of cancer but not in normal tissues. We describe a novel αvβ6-mediated signaling pathway that has profound effects on the microenvironment. We show that αvβ6 is transferred from cancer cells to monocytes, including β6-null monocytes, by exosomes and that monocytes from prostate cancer patients, but not from healthy volunteers, express αvβ6. Cancer cell exosomes, purified via density gradients, promote M2 polarization, whereas αvβ6 down-regulation in exosomes inhibits M2 polarization in recipient monocytes. Also, as evaluated by our proteomic analysis, αvβ6 down-regulation causes a significant increase in donor cancer cells, and their exosomes, of two molecules that have a tumor suppressive role, STAT1 and MX1/2. Finally, using the Pten^pc-/- prostate cancer mouse model, which carries a prostate epithelial-specific Pten deletion, we demonstrate that αvβ6 inhibition in vivo causes up-regulation of STAT1 in cancer cells. Our results provide evidence of a novel mechanism that regulates M2 polarization and prostate cancer progression through transfer of αvβ6 from cancer cells to monocytes through exosomes.

CD44v6 increases gastric cancer malignant phenotype by modulating adipose stromal cell-mediated ECM remodeling

CD44, an abundantly expressed adhesion molecule, and its alternative splice variants have been associated with tumorigenesis and metastasis. In the context of gastric cancer (GC), de novo expression of CD44 variant 6 (CD44v6) is found in more than 60% of GCs, but its role in the pathogenesis and progression of this type of cancer remains unclear. Using a combination of media conditioning experiments and decellularized extracellular matrices (ECMs), this study investigates the hypothesis that CD44v6 overexpression enhances tumor cell malignant behavior by modulating stromal cell-mediated ECM remodeling. Our findings indicate that soluble factors secreted by CD44v6 expressing GC cells particularly increase proliferation and myofibroblastic differentiation of adipose stromal cells (ASCs). These changes in ASC phenotype mediate the deposition of fibrotic/desmoplastic ECM that, in turn, stimulates GC proliferation and inhibits GC clustering. Pharmacological inhibition of matrix metalloproteinase (MMP) activity in tumor cells abrogated matrix-induced changes in tumor cell malignant behavior. Additionally, studies in mice confirmed the pathological relevance of CD44v6 expression and consequential changes in ECM remodeling to gastric tumorigenesis in vivo. Collectively, these results indicate a direct link between CD44v6, ECM remodeling, and GC malignant behavior opening new insights into potential CD44v6-targeted therapies.

The key role of extracellular vesicles in the metastatic process

Extracellular vesicles (EVs), including exosomes, have a key role in the paracrine communication between organs and compartments. EVs shuttle virtually all types of biomolecules such as proteins, lipids, nucleic acids, metabolites and even pharmacological compounds. Their ability to transfer their biomolecular cargo into target cells enables EVs to play a key role in intercellular communication that can regulate cellular functions such as proliferation, apoptosis and migration. This has led to the emergence of EVs as a key player in tumor growth and metastasis through the formation of "tumor niches" in target organs. Recent data have also been shown that EVs may transform the microenvironment of primary tumors thus favoring the selection of cancer cells with a metastatic behavior. The release of EVs from resident non-malignant cells may contribute to the metastatic processes as well. However, cancer EVs may induce malignant transformation in resident mesenchymal stem cells, suggesting that the metastatic process is not exclusively due to circulating tumor cells. In this review, we outline and discuss evidence-based roles of EVs in actively regulating multiple steps of the metastatic process and how we can leverage EVs to impair metastasis.

Extracellular vesicles are integral and functional components of the extracellular matrix

Extracellular vesicles (EV) are small plasma membrane-derived particles released into the extracellular space by virtually all cell types. Recently, EV have received increased interest because of their capability to carry nucleic acids, proteins, lipids and signaling molecules and to transfer their cargo into the target cells. Less attention has been paid to their role in modifying the composition of the extracellular matrix (ECM), either directly or indirectly via regulating the ability of target cells to synthesize or degrade matrix molecules. Based on recent results, EV can be considered one of the structural and functional components of the ECM that participate in matrix organization, regulation of cells within it, and in determining the physical properties of soft connective tissues, bone, cartilage and dentin. This review addresses the relevance of EV as specific modulators of the ECM, such as during the assembly and disassembly of the molecular network, signaling through the ECM and formation of niches suitable for tissue regeneration, inflammation and tumor progression. Finally, we assess the potential of these aspects of EV biology to translational medicine.