Microvesicles secreted by macrophages shuttle invasion-potentiating microRNAs into breast cancer cells

Exosome-mediated cell-cell communication in tumor progression

Exosomes, which are 30-150 nm lipid bilayer vehicles, have been recognized as one of the most crucial components of the tumor microenvironment. Exosomes transfer specific lipid, nucleic acids, proteins and other bioactive molecules from the donor cells to the recipient cells. Accumulating evidence has suggested that cancer cells and the tumor associated stromal cells can release and receive exosomes, inside of which the components and amounts are greatly changed. Pioneering studies have revealed that these exosomes play essential roles in tumor progression. Here we summarize the recent advances in this field, by focusing on the exosome biogenesis in the cancer condition, and their biological function in angiogenesis, metastasis and chemo-resistance of tumor. The review would not only provide a summary of this field, but also insights and perspectives on exosome-based strategies in cancer diagnoses, prevention and therapy.

Arsenic Alters Exosome Quantity and Cargo to Mediate Stem Cell Recruitment Into a Cancer Stem Cell-Like Phenotype

Inorganic arsenic is a human carcinogen that can target the prostate. Accumulating evidence suggests arsenic can disrupt stem cell (SC) dynamics during the carcinogenic process. Previous work demonstrated arsenic-transformed prostate epithelial (CAsE-PE) cells can recruit prostate SCs into rapidly acquiring a cancer SC (CSC) phenotype via the secretion of soluble factors. Exosomes are small, membrane-derived vesicles that contain lipids, RNA, and proteins, and actively contribute to cancer initiation and progression when taken up by target cells. Here we hypothesized that CAsE-PE cells are recruiting SCs to a CSC-like phenotype via exosomal signaling. CAsE-PE cells secreted 700% more exosomes than parental RWPE-1 cells. CAsE-PE exosomes were enriched with oncogenic factors, including oncogenes (KRAS, NRAS, VEFGA, MYB, and EGFR), inflammation-related (cyclooxygenase-2, interleukin 1B (IL1B), IL6, transforming growth factor-β, and tumor necrosis factor-A), and apoptosis-related (CASP7, CASP9, and BCL2) transcripts, and oncogenesis-associated microRNAs. When compared with SCs cultured in exosome-depleted conditioned medium (CM), SCs cultured in CM containing CAsE-PE-derived exosomes showed increased (198%) matrix metalloproteinase activity and underwent an epithelial-to-mesenchymal transition in morphology, suggesting an exosome-mediated transformation. KRAS plays an important role in arsenic carcinogenesis. Although KRAS transcript (>24 000%) and protein (866%) levels were elevated in CAsE-PE exosomes, knock-down of KRAS in these cells only partially mitigated the CSC-like phenotype in cocultured SCs. Collectively, these results suggest arsenic impacts both exosomal quantity and cargo. Exosomal KRAS is only minimally involved in this recruitment, and additional factors (eg, cancer-associated miRNAs) likely also play a role. This work furthers our mechanistic understanding of how arsenic disrupts SC dynamics and influences the tumor microenvironment during carcinogenesis.

The Interplay between Circulating Tumor Cells and the Immune System: From Immune Escape to Cancer Immunotherapy

Circulating tumor cells (CTCs) have aroused increasing interest not only in mechanistic studies of metastasis, but also for translational applications, such as patient monitoring, treatment choice, and treatment change due to tumor resistance. In this review, we will assess the state of the art about the study of the interactions between CTCs and the immune system. We intend to analyze the impact that the cells of the immune system have in limiting or promoting the metastatic capability of CTCs. To this purpose, we will examine studies that correlate CTCs, immune cells, and patient prognosis, and we will also discuss relevant animal models that have contributed to the understanding of the mechanisms of immune-mediated metastasis. We will then consider some studies in which CTCs seem to play a promising role in monitoring cancer patients during immunotherapy regimens. We believe that, from an accurate and profound knowledge of the interactions between CTCs and the immune system, new immunotherapeutic strategies against cancer might emerge in the future.

Circulating miRNAs as biomarkers for early diagnosis of coronary artery disease

INTRODUCTION

Coronary artery disease (CAD) contributes to a huge number of human death worldwide. The early diagnosis can arrest the development of CAD and effectively lower the mortality rate. Recently, circulating miRNAs emerged as CAD biomarkers.

AREAS COVERED

Many efforts were paid to explore early diagnostic biomarkers of CAD. Some proteins have been used as diagnostic golden standard. However, the diagnostic and prognostic value of them is limited. MicroRNAs (miRNAs), a class of small noncoding RNAs, have been illustrated to regulate gene expression. The dysfunction of miRNAs is associated with CAD. MiRNAs presenting stably in body fluids are called circulating miRNAs. The altered expression of specific circulating miRNAs has been discovered in CAD and reported to affect the pathogenesis of CAD. We reviewed the recent data about circulating miRNAs regarding their potential roles in diagnosis, prognosis and therapeutic strategies for CAD. Additionally, we also summarized the current knowledge about circulating miRNA formation and detection.

EXPERT OPINION

Compared with traditional diagnostic tools, circulating miRNAs have many strongpoints, suggesting that circulating miRNAs can serve as promising biomarkers for the early diagnosis and prognosis of CAD.

Tumor-derived exosomes in cancer metastasis risk diagnosis and metastasis therapy

Exosomes are endosomes secreted from the membrane by exocytosis as multivesicular bodies and are generally defined by their spherical, unilamellar morphology, size and the expression of specific biomarkers used for diagnosis or therapy targets. Recent research has reported a higher relationship between exosome enrichment and tumor disease development. In this review, we discuss exosome intercellular communication and functions in the pathology of disease, especially on the cancer metastasis related with exosome. We introduce how exosomes from cancer and stem cancer cells target different organs through transporting molecular proteins of exosome inclusions to improve or inhibit cancer metastasis as well as highlight exosome therapy strategies for tumor pathology involving microRNAs.

Effects of miRNAs on functions of breast cancer stem cells and treatment of breast cancer

Breast cancer is one of the most common malignancies for women, which accounts for 30% of all female malignancies. The formation of breast cancer stem cells (BCSCs) is attributed to the acquisition of stemness of tumor cells. With self-renewal potential, these stem cells are insensitive to either radiotherapy or chemotherapy but are significant in regulating tumor behaviors and drug resistance. MicroRNA (miRNA) is a kind of noncoding small RNA for negatively regulating gene expressions. Research findings suggest that many miRNAs specifically regulate the expression of target genes and signal pathways of BCSCs. They play an important role in self-renewal, growth, and metastasis of breast cancer cells as potential targets for treating breast cancer. These signal pathways include phosphatase and tensin homolog deleted on chromosome 10-phosphatidylinositol 3-kinase/Akt, Wnt/β-catenin, Notch, and so on. This paper reviews the progress of research about miRNAs in self-renewal, metastasis, epithelial-mesenchymal transition and metastasis, mediation of resistance to chemotherapies, and treatment of breast cancer.

MicroRNA miR-223 as regulator of innate immunity

MicroRNAs were discovered more than 2 decades ago and have profound impact on diverse biological processes. Specific microRNAs have important roles in modulating the innate immune response and their dysregulation has been demonstrated to contribute to inflammatory diseases. MiR-223 in particular, is very highly expressed and tightly regulated in hematopoietic cells. It functions as key modulator for the differentiation and activation of myeloid cells. The central role of miR-223 in myeloid cells, especially neutrophil and macrophage differentiation and activation has been studied extensively. MiR-223 contributes to myeloid differentiation by enhancing granulopoiesis while inhibiting macrophage differentiation. Uncontrolled myeloid activation has detrimental consequences in inflammatory disease. MiR-223 serves as a negative feedback mechanism controlling excessive innate immune responses in the maintenance of myeloid cell homeostasis. This review summarizes several topics covering the function of miR-223 in myeloid differentiation, neutrophil and macrophage functions, as well as in inflammatory diseases including acute respiratory distress syndrome and inflammatory bowel disease. In addition, nonmyeloid functions of miR-223 are also discussed in this review. Therapeutic enhancement of miR-223 to dampen inflammatory targets is also highlighted as potential treatment to control excessive innate immune responses during mucosal inflammation.

Deciphering Non-coding RNAs in Cardiovascular Health and Disease

After being long considered as “junk” in the human genome, non-coding RNAs (ncRNAs) currently represent one of the newest frontiers in cardiovascular disease (CVD) since they have emerged in recent years as potential therapeutic targets. Different types of ncRNAs exist, including small ncRNAs that have fewer than 200 nucleotides, which are mostly known as microRNAs (miRNAs), and long ncRNAs that have more than 200 nucleotides. Recent discoveries on the role of ncRNAs in epigenetic and transcriptional regulation, atherosclerosis, myocardial ischemia/reperfusion (I/R) injury and infarction (MI), adverse cardiac remodeling and hypertrophy, insulin resistance, and diabetic cardiomyopathy prompted vast interest in exploring candidate ncRNAs for utilization as potential therapeutic targets and/or diagnostic/prognostic biomarkers in CVDs. This review will discuss our current knowledge concerning the roles of different types of ncRNAs in cardiovascular health and disease and provide some insight on the cardioprotective signaling pathways elicited by the non-coding genome. We will highlight important basic and clinical breakthroughs that support employing ncRNAs for treatment or early diagnosis of a variety of CVDs, and also depict the most relevant limitations that challenge this novel therapeutic approach.

MEF2 and the tumorigenic process, hic sunt leones

While MEF2 transcription factors are well known to cooperate in orchestrating cell fate and adaptive responses during development and adult life, additional studies over the last decade have identified a wide spectrum of genetic alterations of MEF2 in different cancers. The consequences of these alterations, including triggering and maintaining the tumorigenic process, are not entirely clear. A deeper knowledge of the molecular pathways that regulate MEF2 expression and function, as well as the nature and consequences of MEF2 mutations are necessary to fully understand the many roles of MEF2 in malignant cells. This review discusses the current knowledge of MEF2 transcription factors in cancer.

New insights into the biological impacts of immune cell-derived exosomes within the tumor environment

Exosomes are a group of nano-sized membrane vesicles that transfer proteins, nucleic acids, and lipids to nearby and faraway cells, playing an important role in the intercellular communication within the extracellular environment. Emerging evidences show that exosomes derived from immunocytes, including dendritic cells, T cells, B cells, macrophages, natural killer cells and myeloid-derived suppressor cells, can play an intimate role in the crosstalk among immunocytes in a tumor microenvironment. In this review, we highlight that under tumor conditions, immune cells and tumor cells can be influenced by immunocyte-derived exosomes, resulting in modifications of their phenotype and function. Thus, a better understanding of exosomes derived from different immunocytes would provide novel strategies in generating effective vaccines or improving treatment efficacy in anticancer therapies.

MiRNAs: dynamic regulators of immune cell functions in inflammation and cancer

MicroRNAs (miRNAs), small noncoding RNA molecules, have emerged as important regulators of almost all cellular processes. By binding to specific sequence motifs within the 3'- untranslated region of their target mRNAs, they induce either mRNA degradation or translational repression. In the human immune system, potent miRNAs and miRNA-clusters have been discovered, that exert pivotal roles in the regulation of gene expression. By targeting cellular signaling hubs, these so-called immuno-miRs have fundamental regulative impact on both innate and adaptive immune cells in health and disease. Importantly, they also act as mediators of tumor immune escape. Secreted by cancer cells and consecutively taken up by immune cells, immuno-miRs are capable to influence immune functions towards a blunted anti-tumor response, thus shaping a permissive tumor environment. This review provides an overview of immuno-miRs and their functional impact on individual immune cell entities. Further, implications of immuno-miRs in the amelioration of tumor surveillance are discussed.

Exosome: emerging biomarker in breast cancer

Exosomes are nano-sized membrane vesicles released by a variety of cell types, and are thought to play important roles in intercellular communications. In breast cancer, through horizontal transfer of various bioactive molecules, such as proteins and mRNAs, exosomes are emerging as local and systemic cell-to-cell mediators of oncogenic information and play an important role on cancer progression. This review outlines the current knowledge and concepts concerning the exosomes involvement in breast cancer pathogenesis (including tumor initiation, invasion and metastasis, angiogenesis, immune system modulation and tumor microenvironment) and cancer therapy resistance. Moreover, the potential use of exosomes as promising diagnostic and therapeutic biomarkers in breast cancer are also discussed.

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

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

Microenvironmental Signals and Biochemical Information Processing: Cooperative Determinants of Intratumoral Plasticity and Heterogeneity

Intra-tumor cellular heterogeneity is a major challenge in cancer therapy. Tumors are composed of multiple phenotypic subpopulations that vary in their ability to initiate metastatic tumors and in their sensitivity to chemotherapy. In many cases, cells can transition between these subpopulations, not by genetic mutation, but instead through reversible changes in signal transduction or gene expression programs. This plasticity begins at the level of the microenvironment where local autocrine and paracrine signals, exosomes, tumor–stroma interactions, and extracellular matrix (ECM) composition create a signaling landscape that varies over space and time. The integration of this complex array of signals engages signaling pathways that control gene expression. The resulting modulation of gene expression programs causes individual cells to sample a wide array of phenotypic states that support tumor growth, dissemination, and therapeutic resistance. In this review, we discuss how information flows dynamically within the microenvironmental landscape to inform cell state decisions and to create intra-tumoral heterogeneity. We address the role of plasticity in the acquisition of transient and prolonged drug resistant states and discuss how targeted pharmacological modification of the signaling landscape may be able to constrain phenotypic plasticity, leading to improved treatment responses.

The multifaceted role of exosomes in cancer progression: diagnostic and therapeutic implications [corrected]

BACKGROUND

Recent advances in cancer biology have highlighted the relevance of exosomes and nanovesicles as carriers of genetic and biological messages between cancer cells and their immediate and/or distant environments. It has been found that these molecular cues may play significant roles in cancer progression and metastasis. Cancer cells secrete exosomes containing diverse molecules that can be transferred to recipient cells and/or vice versa to induce a plethora of biological processes, including angiogenesis, metastasis formation, therapeutic resistance, epithelial-mesenchymal transition and epigenetic/stemness (re)programming. While exosomes interact with cells within the tumour microenvironment to promote tumour growth, these vesicles can also facilitate the process of distant metastasis by mediating the formation of pre-metastatic niches. Next to their tumour promoting effects, exosomes have been found to serve as potential tools for cancer diagnosis and therapy. The ease of isolating exosomes and their content from different body fluids has led to the identification of diagnostic and prognostic biomarker signatures, as well as to predictive biomarker signatures for therapeutic responses. Exosomes can also be used as cargos to deliver therapeutic anti-cancer drugs, and they can be engineered to serve as vaccines for immunotherapy. Additionally, it has been found that inhibition of exosome secretion, and thus the transfer of oncogenic molecules, holds promise for inhibiting tumour growth. Here we provide recent information on the diverse roles of exosomes in various cellular and systemic processes governing cancer progression, and discuss novel strategies to halt this progression using exosome-based targeted therapies and methods to inhibit exosome secretion and the transfer of pro-tumorigenic molecules.

CONCLUSIONS

This review highlights the important role of exosomes in cancer progression and its implications for (non-invasive) diagnostics and the development of novel therapeutic strategies, as well as its current and future applications in clinical trials.

The Double Face of Exosome-Carried MicroRNAs in Cancer Immunomodulation

In recent years many articles have underlined the key role of nanovesicles, i.e., exosomes, as information carriers among biological systems including cancer. Tumor-derived exosomes (TEXs) are key players in the dynamic crosstalk between cancer cells and the microenvironment while promote immune system control evasion. In fact, tumors are undoubtedly capable of silencing the immune response through multiple mechanisms, including the release of exosomes. TEXs have been shown to boost tumor growth and promote progression and metastatic spreading via suppression or stimulation of the immune response towards cancer cells. The advantage of immunotherapeutic treatment alone over combining immuno- and conventional therapy is currently debated. Understanding the role of tumor exosome-cargo is of crucial importance for our full comprehension of neoplastic immonosuppression and for the construction of novel therapies and vaccines based on (nano-) vesicles. Furthermore, to devise new anti-cancer approaches, diverse groups investigated the possibility of engineering TEXs by conditioning cancer cells’ own cargo. In this review, we summarize the state of art of TEX-based immunomodulation with a particular focus on the molecular function of non-coding family genes, microRNAs. Finally, we will report on recent efforts in the study of potential applications of engineered exosomes in cancer immunotherapy.

MicroRNAs in type 2 immunity

Type 2 immunity drives the pathology of allergic diseases and is necessary for expulsion of parasitic worms as well as having important implications in tumor progression. Over the last decade, a new research field has emerged describing a significant link between type 2 immunity and cancer development, called AllergoOncology. Thus, type 2 immune responses must be carefully regulated to mediate effective protection against damaging environmental factors, yet avoid excessive activation and immunopathology. Regulation of gene expression by microRNAs is required for normal behavior of most mammalian cells and has been studied extensively in the context of cancer. Although microRNA regulation of the immune system in cancer is well established and includes type 2 immune reactions in the tumor microenvironment, the involvement of microRNAs in these responses initiated by allergens, parasites or other environmental factors is just emerging. In this review, we focus on recent advances which increase the understanding of microRNA-mediated regulation of key mechanisms of type 2 immunity.

The Inner and Outer Qualities of Extracellular Vesicles for Translational Purposes in Breast Cancer

Breast cancer (BC) is the second most common cause of cancer mortality of women worldwide. BC is a systemic disease with a highly heterogeneous course of disease. Therefore, prognostic and diagnostic biomarkers are required to improve the clinical risk management. Cancer-derived or cancer-associated extracellular vesicles (EVs) procured from the bloodstream of BC patients offer a novel platform for the qualitative and quantitative screening and establishment of biomarkers. Here, we focus on common aspects of EVs, on the function of BC-derived EVs and their translational potential considering the EV abundancy, intravesicular as well as outer membrane-anchored composition and current challenges of implementation in clinical practice.

Roles of Macrophage Exosomes in Immune Response to Calcium Oxalate Monohydrate Crystals

In kidney stone disease, macrophages secrete various mediators via classical secretory pathway and cause renal interstitial inflammation. However, whether their extracellular vesicles, particularly exosomes, are involved in kidney stone pathogenesis remained unknown. This study investigated alterations in exosomal proteome of U937-derived macrophages (by phorbol-12-myristate-13-acetate activation) after exposure to calcium oxalate monohydrate (COM) crystals for 16-h using 2-DE-based proteomics approach. Six significantly altered proteins in COM-treated exosomes were successfully identified by nanoscale liquid chromatography–electrospray ionization–electron transfer dissociation tandem mass spectrometry as proteins involved mainly in immune processes, including T-cell activation and homeostasis, Fcγ receptor-mediated phagocytosis, interferon-γ (IFN-γ) regulation, and cell migration/movement. The decreased heat shock protein 90-beta (HSP90β) and increased vimentin were confirmed by Western blotting. ELISA showed that the COM-treated macrophages produced greater level of interleukin-1β (IL-1β), one of the markers for inflammasome activation. Functional studies demonstrated that COM-treated exosomes enhanced monocyte and T-cell migration, monocyte activation and macrophage phagocytic activity, but on the other hand, reduced T-cell activation. In addition, COM-treated exosomes enhanced production of proinflammatory cytokine IL-8 by monocytes that could be restored to its basal level by small-interfering RNA targeting on vimentin (si-Vimentin). Moreover, si-Vimentin could also abolish effects of COM-treated exosomes on monocyte and T-cell migration as well as macrophage phagocytic activity. These findings provided some implications to the immune response during kidney stone pathogenesis via exosomal pathway of macrophages after exposure to COM crystals.

Biogenesis and function of extracellular vesicles in cancer

Extracellular vesicles (EVs) are heterogeneous multi-signal messengers that support cancer growth and dissemination by mediating the tumor-stroma crosstalk. Exosomes are a subtype of EVs that originate from the limiting membrane of late endosomes, and as such contain information linked to both the intrinsic cell "state" and the extracellular signals cells received from their environment. Resolving the signals affecting exosome biogenesis, cargo sorting and release will increase our understanding of tumorigenesis. In this review we highlight key cell biological processes that couple exosome biogenesis to cargo sorting in cancer cells. Moreover, we discuss how the bidirectional communication between tumor and non-malignant cells affect cancer growth and metastatic behavior.

MiR-223-5p works as an oncomiR in vulvar carcinoma by TP63 suppression

MiR-223-5p has been previously mentioned to be associated with tumor metastasis in HPV negative vulvar carcinomas, such as in several other tumor types. In the present study, we hypothesized that this microRNA would be important in vulvar cancer carcinogenesis and progression. To investigate this, we artificially mimicked miR-223-5p expression in a cell line derived from lymph node metastasis of vulvar carcinoma (SW962) and performed in vitro assays. As results, lower cell proliferation (p < 0.01) and migration (p < 0.001) were observed when miR-223-5p was overexpressed. In contrast, increased invasive potential of these cells was verified (p < 0.004). In silico search indicated that miR-223-5p targets TP63, member of the TP53 family of proteins, largely described with importance in vulvar cancer. We experimentally demonstrated that this microRNA is capable to decrease levels of p63 at both mRNA and protein levels (p < 0.001, and p < 0.0001; respectively). Also, a significant inverse correlation was observed between miR-223-5p and p63 expressions in tumors from patients (p = 0.0365). Furthermore, low p63 protein expression was correlated with deeper tumor invasion (p = 0.0491) and lower patient overall survival (p = 0.0494). Our study points out miR-223-5p overexpression as a putative pathological mechanism of tumor invasion and a promising therapeutic target and highlights the importance of both miR-223-5p and p63 as prognostic factors in vulvar cancer. Also, it is plausible that the evaluation of p63 expression in vulvar cancer at the biopsy level may bring important contribution on prognostic establishment and in elaborating better surgical approaches for vulvar cancer patients.

An obligatory anaerobic Salmonella typhimurium strain redirects M2 macrophages to the M1 phenotype

A genetically engineered Salmonella typhimurium strain that may be applied in the medically useful therapeutic strategy of using bacterial agents to target breast cancer in a tumor-bearing nude mouse model has been previously reported. Furthermore, immune cell accumulation in breast tumor types has been observed, particularly distributed in regions surrounding the bacteria. M2 macrophages are associated with breast cancer aggressiveness, whereas M1 macrophages are prone to devouring bacteria and killing cancer cells. Therefore, this engineered tumor-targeting salmonella strain was used in an attempt to reverse the phenotype of M2 macrophages into the M1 phenotype. Subsequent to the co-culture of M2 macrophages with the bacteria for a short time, >50% of the M2 macrophages were invaded by bacteria. These M2 macrophages exhibited a decreased expression of mannose receptor (an M2 phenotypic marker) and increased expression of human leukocyte antigen-antigen D related (an M1 phenotypic marker). The results of the present study indicated that differentiated M2 macrophages may be redirected into the M1 phenotype following exposure to the engineered bacteria stimulus. This effect may be a potential mechanism by which bacteria retard tumor growth. Thus, this engineered bacterium may be a useful candidate for targeting and redirecting M2 macrophages into the M1 phenotype.

Exosomes: Outlook for Future Cell-Free Cardiovascular Disease Therapy

Cardiovascular diseases are the number one cause of death globally with an estimated 7.4 million people dying from coronary heart disease. Studies have been conducted to identify the therapeutic utility of exosomes in many diseases, including cardiovascular diseases. It has been demonstrated that exosomes are immune modulators, can be used to treat cardiac ischemic injury, pulmonary hypertension and many other diseases, including cancers. Exosomes can be used as a biomarker for disease and cell-free drug delivery system for targeting the cells. Many studies suggest that exosomes can be used as a cell-free vaccine for many diseases. In this chapter, we explore the possibility of future therapeutic potential of exosomes in various cardiovascular diseases.

Extracellular vesicles regulate immune responses and cellular function in intestinal inflammation and repair

Tightly controlled communication among the various resident and recruited cells in the intestinal tissue is critical for maintaining tissue homeostasis, re-establishment of the barrier function and healing responses following injury. Emerging evidence convincingly implicates extracellular vesicles (EVs) in facilitating this important cell-to-cell crosstalk by transporting bioactive effectors and genetic information in healthy tissue and disease. While many aspects of EV biology, including release mechanisms, cargo packaging, and uptake by target cells are still not completely understood, EVs contribution to cellular signaling and function is apparent. Moreover, EV research has already sparked a clinical interest, as a potential diagnostic, prognostic and therapeutic tool. The current review will discuss the function of EVs originating from innate immune cells, namely, neutrophils, monocytes and macrophages, as well as intestinal epithelial cells in healthy tissue and inflammatory disorders of the intestinal tract. Our discussion will specifically emphasize the contribution of EVs to the regulation of vascular and epithelial barrier function in inflamed intestines, wound healing, as well as trafficking and activity of resident and recruited immune cells.

MiRNAs at the Crossroads between Innate Immunity and Cancer: Focus on Macrophages

Innate immune cells form an integrative component of the tumor microenvironment (TME), which can control or prevent tumor initiation and progression, due to the simultaneous processing of both anti- and pro-growth signals. This decision-making process is a consequence of gene expression changes, which are in part dependent on post-transcriptional regulatory mechanisms. In this context, microRNAs have been shown to regulate both recruitment and activation of specific tumor-associated immune cells in the TME. This review aims to describe the most important microRNAs that target cancer-related innate immune pathways. The role of exosomal microRNAs in tumor progression and microRNA-based therapeutic strategies are also discussed.

Non-apoptotic cell death in malignant tumor cells and natural compounds

Traditional cancer therapy is mainly targeting on enhancing cell apoptosis, however, it is well established that many cancer cells are chemo-resistant and defective in apoptosis induction. Therefore, it may have important therapeutic implications to exploit some novel natural compounds based on non-apoptotic programmed cell death. Currently, accumulating evidence shows that the compounds from nature source can induce non-apoptotic programmed cell death in cancer cells, and therefore these natural compounds have gained a great promise for the future anticancer therapeutics. In this review, we will concentrate our efforts on the latest developments regarding major forms of non-apoptotic programmed cell death--autophagic cell death, necroptosis, ferroptosis, pyroptosis, glutamoptosis and exosome-associated cell death. Our increased understanding of the role of natural compounds in regulating non-apoptotic programmed cell death will hopefully provide prospective strategies for cancer therapy.

Emerging roles of microRNAs in cancer

MicroRNAs (miRNAs) have emerged as important regulators of human carcinogenesis by affecting the expression of key oncogenes and tumor suppressor genes. MiRNAs elicit their function through post-transcriptional regulation of the mRNA translation into protein as well as functioning as ligands for proteic receptors called miRceptors. Our understanding of the role of miRNAs in cancer biology has enormously improved in the last few years, providing the rationale for new therapeutics. Here we discuss the most recent findings on the role of miRNAs in modulating cancer biology with a specific focus on their role as modulators of the biology of the tumor microenvironment both as cargo of extracellular vesicles and as extra-vesicular miRNAs.

The functions and clinical applications of tumor-derived exosomes

Exosomes are extracellular vesicles with diameters ranging from 30 to 150 nm. They can be secreted by all cell types and transfer information in the form of their contents, which include proteins, lipids and nucleic acids, to other cells throughout the body. They have roles in normal physiological processes as well as in disease development. Here, we review recent findings regarding tumor-derived exosomes, including methods for their extraction and preservation. We also describe the actions of exosomes in tumorigenesis. The exosomal antigen-presenting effect during antitumor immune responses and its suppressive function in immune tolerance are discussed. Finally, we describe the potential application of exosomes to cancer therapy and liquid biopsy.

Exosomes confer pro-survival signals to alter the phenotype of prostate cells in their surrounding environment

Prostate cancer (PCa) is the most frequently diagnosed cancer in men. Current research on tumour-related extracellular vesicles (EVs) suggests that exosomes play a significant role in paracrine signaling pathways, thus potentially influencing cancer progression via multiple mechanisms. In fact, during the last decade numerous studies have revealed the role of EVs in the progression of various pathological conditions including cancer. Moreover, differences in the proteomic, lipidomic, and cholesterol content of exosomes derived from PCa cell lines versus benign prostate cell lines confirm that exosomes could be excellent biomarker candidates. As such, as part of an extensive proteomic analysis using LCMS we previously described a potential role of exosomes as biomarkers for PCa. Current evidence suggests that uptake of EV's into the local tumour microenvironment encouraging us to further examine the role of these vesicles in distinct mechanisms involved in the progression of PCa and castration resistant PCa. For the purpose of this study, we hypothesized that exosomes play a pivotal role in cell-cell communication in the local tumour microenvironment, conferring activation of numerous survival mechanisms during PCa progression and development of therapeutic resistance. Our in vitro results demonstrate that PCa derived exosomes significantly reduce apoptosis, increase cancer cell proliferation and induce cell migration in LNCaP and RWPE-1 cells. In conjunction with our in vitro findings, we have also demonstrated that exosomes increased tumor volume and serum PSA levels in vivo when xenograft bearing mice were administered DU145 cell derived exosomes intravenously. This research suggests that, regardless of androgen receptor phenotype, exosomes derived from PCa cells significantly enhance multiple mechanisms that contribute to PCa progression.

Extracellular Vesicles and the Promise of Continuous Liquid Biopsies

The rapid and accurate diagnosis of patients with minimally invasive procedures was once only found in science fiction. However, the discovery of extracellular vesicles (EVs) and their near ubiquity in body fluids, coupled with the advent of inexpensive next generation sequencing techniques and EV purification protocols, promises to make science fiction a reality. Purifying and sequencing the RNA content of EV from routine blood draws and urine samples are likely to enable pathologists and physicians to diagnose and track the progress of diseases in many inaccessible tissues in the near future. Here we present the evolutionary background of EV, summarize the biology of EV formation and cargo selection, and discuss the current barriers to making continuous liquid biopsies through the use of EV a science reality.

Macrophage-Dependent Cytoplasmic Transfer during Melanoma Invasion In Vivo

Interactions between tumor cells and tumor-associated macrophages play critical roles in the initiation of tumor cell motility. To capture the cellular interactions of the tumor microenvironment with high-resolution imaging, we directly visualized tumor cells and their interactions with macrophages in zebrafish. Live imaging in zebrafish revealed that macrophages are dynamic, yet maintain sustained contact with tumor cells. In addition, the recruitment of macrophages to tumor cells promotes tumor cell dissemination. Using a Cre/LoxP strategy, we found that macrophages transfer cytoplasm to tumor cells in zebrafish and mouse models. Remarkably, macrophage cytoplasmic transfer correlated with melanoma cell dissemination. We further found that macrophages transfer cytoplasm to tumor cells upon cell contact in vitro. Thus, we present a model in which macrophage/tumor cell contact allows for the transfer of cytoplasmic molecules from macrophages to tumor cells corresponding to increased tumor cell motility and dissemination.

The Role of micro RNAs in Breast Cancer Metastasis: Preclinical Validation and Potential Therapeutic Targets

Despite the approval of several molecular therapies in the last years, breast cancer-associated death ranks as the second highest in women. This is due to metastatic disease, which represents a challenge for treatment. A better understanding of the molecular mechanisms of metastasis is, therefore, of paramount importance. In this review we summarize the role of micro RNAs (miRs) involved in metastasis of breast cancer. We present an overview on metastasis-promoting, -suppressing and context-dependent miRs with both activities. We have categorized the corresponding miRs according to their target classes, interaction with stromal cells or exosomes. The pathways affected by individual miRs are outlined in regard to in vitro properties, activity in metastasis-related in vivo models and clinical significance. Current approaches that may be suitable for therapeutic inhibition or restauration of miR activity are outlined. Finally, we discuss the delivery bottlenecks which present as a major challenge in nucleic acid (miR)-based therapies.

Cell-secreted vesicles containing microRNAs as regulators of gamete maturation

Mammalian gamete maturation requires extensive signaling between germ cells and their surrounding somatic cells. In the ovary, theca cells, mural granulosa cells, cumulus cells and the oocyte all secrete factors throughout follicle growth and maturation that are critical for ovulation of a high-quality oocyte with the competence to develop into an embryo. Similarly, maturation of sperm occurs as it transits the epididymis during which epididymal epithelium and sperm exchange secretory factors that are required for sperm to gain motility and fertility. Recent studies in a variety of species have uncovered the presence of cell-secreted vesicles in follicular fluid (microvesicles and exosomes) and epididymal fluid (epididymosomes). Moreover, these cell-secreted vesicles contain small non-coding regulatory RNAs called microRNAs, which can be shuttled between maturing gametes and surrounding somatic cells. Although little is known about the exact mechanism of how microRNAs are loaded into these cell-secreted vesicles or are transferred and modulate gene expression and function in gametes, recent studies clearly suggest that cell-secreted vesicle microRNAs play a role in oocyte and sperm maturation. Moreover, a role for cell-secreted vesicular microRNAs in gamete maturation provides for novel opportunities to modulate and discover new diagnostic markers associated with male or female fertility. This manuscript provides an overview of cell-secreted vesicles in ovarian follicular fluid and epididymal fluid and microRNAs and discusses recent discoveries on the potential function of cell-secreted vesicles as carriers of microRNAs in oocyte and sperm maturation.

Overview of MicroRNA Biogenesis, Mechanisms of Actions, and Circulation

MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. The majority of miRNAs are transcribed from DNA sequences into primary miRNAs and processed into precursor miRNAs, and finally mature miRNAs. In most cases, miRNAs interact with the 3' untranslated region (3' UTR) of target mRNAs to induce mRNA degradation and translational repression. However, interaction of miRNAs with other regions, including the 5' UTR, coding sequence, and gene promoters, have also been reported. Under certain conditions, miRNAs can also activate translation or regulate transcription. The interaction of miRNAs with their target genes is dynamic and dependent on many factors, such as subcellular location of miRNAs, the abundancy of miRNAs and target mRNAs, and the affinity of miRNA-mRNA interactions. miRNAs can be secreted into extracellular fluids and transported to target cells via vesicles, such as exosomes, or by binding to proteins, including Argonautes. Extracellular miRNAs function as chemical messengers to mediate cell-cell communication. In this review, we provide an update on canonical and non-canonical miRNA biogenesis pathways and various mechanisms underlying miRNA-mediated gene regulations. We also summarize the current knowledge of the dynamics of miRNA action and of the secretion, transfer, and uptake of extracellular miRNAs.

Overview of MicroRNA Biogenesis, Mechanisms of Actions, and Circulation

MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. The majority of miRNAs are transcribed from DNA sequences into primary miRNAs and processed into precursor miRNAs, and finally mature miRNAs. In most cases, miRNAs interact with the 3' untranslated region (3' UTR) of target mRNAs to induce mRNA degradation and translational repression. However, interaction of miRNAs with other regions, including the 5' UTR, coding sequence, and gene promoters, have also been reported. Under certain conditions, miRNAs can also activate translation or regulate transcription. The interaction of miRNAs with their target genes is dynamic and dependent on many factors, such as subcellular location of miRNAs, the abundancy of miRNAs and target mRNAs, and the affinity of miRNA-mRNA interactions. miRNAs can be secreted into extracellular fluids and transported to target cells via vesicles, such as exosomes, or by binding to proteins, including Argonautes. Extracellular miRNAs function as chemical messengers to mediate cell-cell communication. In this review, we provide an update on canonical and non-canonical miRNA biogenesis pathways and various mechanisms underlying miRNA-mediated gene regulations. We also summarize the current knowledge of the dynamics of miRNA action and of the secretion, transfer, and uptake of extracellular miRNAs.

Exosomes Function in Tumor Immune Microenvironment

Immune cells and mesenchymal stem/stromal cells are the major cellular components in tumor microenvironment that actively migrate to tumor sites by sensing "signals" released from tumor cells. Together with other stromal cells, they form the soil for malignant cell progression. In the crosstalk between tumor cells and its surrounded microenvironment, exosomes exert multiple functions in shaping tumor immune responses. In tumor cells, their exosomes can lead to pro-tumor immune responses, whereas in immune cells, their derived exosomes can operate on tumor cells and regulate their ability to growth, metastasis, even reaction to chemotherapy. Employing exosomes as vehicles for the delivery products to initiate anti-tumor immune responses has striking therapeutic effects on tumor progression. Thus, exosomes are potential therapeutic targets in tumor-related clinical conditions. Here we discuss the role of exosomes in regulating tumor immune microenvironment and future indications for the clinical application of exosomes.

Extracellular miR-1246 promotes lung cancer cell proliferation and enhances radioresistance by directly targeting DR5

MiRNAs in the circulation have been demonstrated to be a type of signaling molecule involved in intercellular communication but little is known about their role in regulating radiosensitivity. This study aims to investigate the effects of extracellular miRNAs induced by ionizing radiation (IR) on cell proliferation and radiosensitivity. The miRNAs in the conditioned medium (CM) from irradiated and non-irradiated A549 lung cancer cells were compared using a microarray assay and the profiles of 21 miRNAs up and down-regulated by radiation were confirmed by qRT-PCR. One of these miRNAs, miR-1246, was especially abundant outside the cells and had a much higher level compared with that inside of cells. The expressions of miR-1246 in both A549 and H446 cells increased along with irradiation dose and the time post-irradiation. By labeling exosomes and miR-1246 with different fluorescence dyes, it was found that the extracellular miR-1246 could shuttle from its donor cells to other recipient cells by a non-exosome associated pathway. Moreover, the treatments of cells with miR-1246 mimic or its antisense inhibitor showed that the extracellular miR-1246 could enhance the proliferation and radioresistance of lung cancer cells. A luciferase reporter-gene transfer experiment demonstrated that the death receptor 5 (DR5) was the direct target of miR-1246, and the kinetics of DR5 expression was opposite to that of miR-1246 in the irradiated cells. Our results show that the oncogene-like extracellular miR-1246 could act as a signaling messenger between irradiated and non-irradiated cells, more importantly, it contributes to cell radioresistance by directly suppressing the DR5 gene.

Exosomal microRNA remodels the tumor microenvironment

Tumor occurrence, progression and metastasis depend on the crosstalk between tumor cells and stromal cells and on extrinsic factors outside the tumor microenvironment. Exosomal microRNA (miRNA) not only is involved in communications within the tumor microenvironment but also mediates communications between the extrinsic environment and tumor microenvironment. However, most reviews have been limited to the role of endogenous exosomal miRNA in remodeling the tumor microenvironment. Hence, we herein review the role of endogenous exosomal miRNA in mediating intercellular crosstalk within the tumor microenvironment, inducing the formation of the premetastatic niche. To place our vision outside the microenvironment, we also summarize for the first time the most recent studies regarding how exogenous miRNA derived from milk, plants and microbes influences the tumor microenvironment. Furthermore, to improve the value of exosomal miRNA in cancer research and clinical applications, we also provide some novel ideas for future research based on the comprehensive role of exosomal miRNA in remodeling the tumor microenvironment.

Factors involved in cancer metastasis: a better understanding to "seed and soil" hypothesis

Metastasis has intrigued researchers for more than 100 years. Despite the development of technologies and therapeutic strategies, metastasis is still the major cause of cancer-related death until today. The famous "seed and soil" hypothesis is widely cited and accepted, and it still provides significant instructions in cancer research until today. To our knowledge, there are few reviews that comprehensively and correlatively focus on both the seed and soil factors involved in cancer metastasis; moreover, despite the fact that increasingly underlying mechanisms and concepts have been defined recently, previous perspectives are appealing but may be limited. Hence, we reviewed factors involved in cancer metastasis, including both seed and soil factors. By integrating new concepts with the classic hypothesis, we aim to provide a comprehensive understanding of the "seed and soil" hypothesis and to conceptualize the framework for understanding factors involved in cancer metastasis. Based on a dynamic overview of this field, we also discuss potential implications for future research and clinical therapeutic strategies.

Genome-wide Profiling of Urinary Extracellular Vesicle microRNAs Associated With Diabetic Nephropathy in Type 1 Diabetes

Introduction

Diabetic nephropathy (DN) is a form of progressive kidney disease that often leads to end-stage renal disease (ESRD). It is initiated by microvascular complications due to diabetes. Although microalbuminuria (MA) is the earliest clinical indication of DN among patients with type 1 diabetes (T1D), it lacks the sensitivity and specificity to detect the early onset of DN. Recently, microRNAs (miRNAs) have emerged as critical regulators in diabetes as well as various forms of kidney disease, including renal fibrosis, acute kidney injury, and progressive kidney disease. Additionally, circulating extracellular miRNAs, especially miRNAs packaged in extracellular vesicles (EVs), have garnered significant attention as potential noninvasive biomarkers for various diseases and health conditions.

Methods

As part of the University of Pittsburgh Epidemiology of Diabetes Complications (EDC) study, urine was collected from individuals with T1D with various grades of DN or MA (normal, overt, intermittent, and persistent) over a decade at prespecified intervals. We isolated EVs from urine and analyzed the small-RNA using NextGen sequencing.

Results

We identified a set of miRNAs that are enriched in urinary EVs compared with EV-depleted samples, and identified a number of miRNAs showing concentration changes associated with DN occurrence, MA status, and other variables, such as hemoglobin A1c levels.

Conclusion

Many of the miRNAs associated with DN occurrence or MA status directly target pathways associated with renal fibrosis (including transforming growth factor-β and phosphatase and tensin homolog), which is one of the major contributors to the pathology of DN. These miRNAs are potential biomarkers for DN and MA.

Exosomal microRNA: a novel biomarker for breast cancer

Breast cancer is the most common invasive malignancy among females worldwide. microRNAs (miRNAs) are small noncoding RNAs that regulate post-transcriptional gene expression by binding to the 3'-untranslated regions of targeted mRNAs. Recently, exosomes have been recognized to play critical roles in breast cancer. miRNAs, as the most important inclusions in exosomes, are stable in the blood and other body fluids, making them ideal candidate biomarkers. In this review, we provide a complex overview of exosomal miRNAs in breast cancer. Particularly, we summarized their critical roles in tumorigenesis and tumor progression, expecting to lay the foundation for future studies using these potential biomarkers.

Inflammation-Stimulated Mesenchymal Stromal Cell-Derived Extracellular Vesicles Attenuate Inflammation

Extracellular vesicles (EVs) secreted by mesenchymal stromal cells (MSCs) have been proposed to be a key mechanistic link in the therapeutic efficacy of cells in response to cellular injuries through paracrine effects. We hypothesize that inflammatory stimulation of MSCs results in the release of EVs that have greater anti-inflammatory effects. The present study evaluates the immunomodulatory abilities of EVs derived from inflammation-stimulated and naive MSCs (MSCEv⁺ and MSCEv, respectively) isolated using a current Good Manufacturing Practice-compliant tangential flow filtration system. Detailed characterization of both EVs revealed differences in protein composition, cytokine profiles, and RNA content, despite similarities in size and expression of common surface markers. MSCEv⁺ further attenuated release of pro-inflammatory cytokines in vitro when compared to MSCEv, with a distinctly different pattern of EV-uptake by activated primary leukocyte subpopulations. The efficacy of EVs was partially attributed to COX2/PGE₂ expression. The present study demonstrates that inflammatory stimulation of MSCs renders release of EVs that have enhanced anti-inflammatory properties partially due to COX2/PGE₂ pathway alteration. Stem Cells 2018;36:79-90.

Interrelation of the Circulating and Tissue MicroRNA-21 with Tissue PDCD4 Expression and the Invasiveness of Iraqi Female Breast Tumors

The changes in the translational repression and variation in mRNA degradation induced by micro RNA are important aspects of tumorigenesis. The association of microRNA-21 with clinicopathologic features and expression of programed cell death 4 (PDCD4) in Iraqi female's with breast tumors has not been studied. MicroRNAs were extracted from a set of 60 breast tumor tissues and blood samples of females with breast cancer and benign breast lesions obtained after breast-reductive surgery, and only blood samples from 30 normal volunteers. These extracts were evaluated for miR-21 expression by quantitative RT-PCR. Analysis of PDCD4 protein expression was carried out as miR-21 target gene by immunohistochemical tests and correlating the results with patients' clinicopathological features. Significant overexpression of miRNA-21 was found in breast cancer group. The fold increase in the miR-21 gene expression was significantly higher in circulating exosomes and breast tissues of breast cancer patients as compared to other groups (P < 0.001). Overexpression of miR-21 was also significantly associated with the advanced tumor stage and histological grade. In breast cancer patients, PDCD4 protein expression was decreased to about 70% of the level in the control group. The delta Ct of exosomal and breast tissue miRNA-21 was negatively associated with PDCD4 expression. In conclusion, the translational repression of the PDCD4 induced by the high expression of miR-21 promotes breast cell transformation and development of breast tumor, and circulating miR-21 level could be applied to the screening panels for early detection of women breast cancer.

Recent advances in exosome-based nanovehicles as RNA interference therapeutic carriers

RNA interference (RNAi) therapeutics (siRNA, miRNA, etc.) represent an emerging medicinal remedy for a variety of ailments. However, their low serum stability and low cellular uptake significantly restrict their clinical applications. Exosomes are biologically derived nanodimensional vesicle ranging from a few nanometers to a hundred. In the last few years, several reports have been published demonstrating the emerging applications of these exogenous membrane vesicles, particularly in carrying different RNAi therapeutics to adjacent or distant targeted cells. In this report, we explored the numerous aspects of exosomes from structure to clinical implications with special emphasis on their application in delivering RNAi-based therapeutics. siRNA and miRNA have attracted great interest in recent years due to their specific application in treating many complex diseases including cancer. We highlight strategies to obviate the challenges of their low bioavailability for gene therapy.

Cancer-derived extracellular vesicles: the 'soil conditioner' in breast cancer metastasis?

It has been recognized that cancer-associated mortality is more often a result of the disrupted physiological functions in multiple organs following metastatic dissemination of cancer cells, rather than the presence and growth of the primary tumor. Despite advances in our understanding of the events leading to cancer initiation, growth, and acquisition of invasive properties, we are still unable to effectively treat metastatic disease. It is now being accepted that the secretion of extracellular vesicles, such as exosomes from cancer cells, has a profound impact on the initiation and propagation of metastatic breast cancer. These cancer-secreted vesicles differ from other means of cellular communication due to their capability of bulk delivery and organotropism. Here, we provide an overview of the role of extracellular vesicles in breast cancer metastasis and discuss key areas that may facilitate our understanding of metastatic breast cancer to guide our efforts towards providing better therapies.

One microenvironment does not fit all: heterogeneity beyond cancer cells

Human cancers exhibit formidable molecular heterogeneity, to a large extent accounting for the incomplete and transitory efficacy of current anti-cancer therapies. However, neoplastic cells alone do not manifest the disease, but conscript a battery of non-tumor cells to enable and sustain hallmark capabilities of cancer. Escaping immunosurveillance is one of such capabilities. Tumors evolve immunosuppressive microenvironment to subvert anti-tumor immunity. In this review, we will focus on tumor-associated myeloid cells, which constitute an essential part of the immune microenvironment and reciprocally interact with cancer cells to establish malignancy toward metastasis. The diversity and plasticity of these cells constitute another layer of heterogeneity, beyond the heterogeneity of cancer cells themselves. We envision that immune microenvironment co-evolves with the genetic heterogeneity of tumor. Addressing the question of how genetically distinct tumors shape and are shaped by unique immune microenvironment will provide an attractive rationale to develop novel immunotherapeutic modalities. Here, we discuss the complex nature of tumor microenvironment, with an emphasis on the cellular and functional heterogeneity among tumor-associated myeloid cells as well as immune environment heterogeneity in the context of a full spectrum of human breast cancers.

Tumor microenvironment heterogeneity: challenges and opportunities

The tumor microenvironment (TME) has been recognized as an integral component of malignancies in breast and prostate tissues, contributing in confounding ways to tumor progression, metastasis, therapy resistance and disease recurrence. Major components of the TME are immune cells, fibroblasts, pericytes, endothelial cells, mesenchymal stroma/stem cells (MSCs), and extracellular matrix (ECM) components. Herein, we discuss the molecular and cellular heterogeneity within the TME and how this presents unique challenges and opportunities for treating breast and prostate cancers.

Extracellular vesicle-mediated transport of non-coding RNAs between stem cells and cancer cells: implications in tumor progression and therapeutic resistance

Recent years have witnessed intensive progress in studying extracellular vesicles (EVs), both for understanding their basic biology and contribution to variety of diseases, biomarker discovery, and their potential as gene delivery vectors and source of innovative therapies. As such, stem cell-derived EVs have contributed significant knowledge which led to the development of cell-free therapies in regenerative medicine. Although, the role of stem cell-derived EVs in maintaining stemness, differentiation and repairing tissue injuries is relatively well-understood; however, knowledge about the contribution of stem cell-derived EVs in cancer progression is just emerging. The aim of this review is, therefore, to discuss the recent developments in stem cell-derived EVs and tumor progression, placing a particular focus on non-coding RNA (ncRNA) mediated cancer progression and resistance against therapies. This includes the failure of normal hematopoiesis and the progression of myeloid neoplasms, enhanced capacity of cancer cells to proliferate and metastasize, and the conversion of normal cells into cancer cells, activation of angiogenic pathways and dormancy in cancer cells. These processes are shared by mesenchymal stem cells (MSCs), cancer stem like-cells and cancer cells in an intricate intratumoral network in order to create self-strengthening tumor niche. In this context, EV-ncRNAs serve as mediators to relay bystander effects of secreting cancer stem cells (CSCs) into recipient cells for priming a tumor permissive environment and relaying therapeutic resistance. Collectively, this knowledge will improve our understandings and approaches in finding new therapeutic targets in the context of CSCs, which could be benefited through engineering EVs for innovative therapies.

Extracellular vesicles as emerging targets in cancer: Recent development from bench to bedside

Extracellular vesicles (EVs) have emerged as important players of cancer initiation and progression through cell-cell communication. They have been recognized as critical mediators of extracellular communications, which promote transformation, growth invasion, and drug-resistance of cancer cells. Interestingly, the secretion and uptake of EVs are regulated in a more controlled manner than previously anticipated. EVs are classified into three groups, (i) exosomes, (ii) microvesicles (MVs), and (iii) apoptotic bodies (ABs), based on their sizes and origins, and novel technologies to isolate and distinguish these EVs are evolving. The biologically functional molecules harbored in these EVs, including nucleic acids, lipids, and proteins, have been shown to induce key signaling pathways in both tumor and tumor microenvironment (TME) cells for exacerbating tumor development. While tumor cell-derived EVs are capable of reprogramming stromal cells to generate a proper tumor cell niche, stromal-derived EVs profoundly affect the growth, resistance, and stem cell properties of tumor cells. This review summarizes and discusses these reciprocal communications through EVs in different types of cancers. Further understanding of the pathophysiological roles of different EVs in tumor progression is expected to lead to the discovery of novel biomarkers in liquid biopsy and development of tumor specific therapeutics. This review will also discuss the translational aspects of EVs and therapeutic opportunities of utilizing EVs in different cancer types.