Exosomal miR-21 derived from arsenite-transformed human bronchial epithelial cells promotes cell proliferation associated with arsenite carcinogenesis

The role of exosome-shuttled miRNAs in heavy metal-induced peripheral tissues and neuroinflammation in Alzheimer's disease

Heavy metal-induced neuroinflammation is a significant pathophysiologic mechanism in Alzheimer's disease (AD). Microglia-mediated neuroinflammation plays a crucial role in the pathogenesis of AD. Multiple miRNAs are differentially expressed in peripheral tissues after heavy metal exposure, and increasing evidence suggests that they are involved in AD progression by regulating microglial homeostasis. Exosomes, which are capable of loading miRNAs and crossing the bloodbrain barrier, serve as mediators of communication between peripheral tissues and the brain. In this review, we summarize the current evidence on the link between miRNAs in peripheral tissues and neuroinflammation in AD after heavy metal exposure and propose a role for miRNAs in the microglial neurodegenerative phenotype (MGnD) of AD. This study will help to elucidate the link between peripheral tissue damage and MGnD-mediated neuroinflammation in AD after heavy metal exposure. Additionally, we summarize the regulatory effects of natural compounds on peripheral tissue-derived miRNAs, which could be potential therapeutic targets for natural compounds to regulate peripheral tissue-derived exosomal miRNAs to ameliorate heavy metal-induced MGnD-mediated neuroinflammation in patients with AD after heavy metal exposure.

Environmental pollutants and exosomes: A new paradigm in environmental health and disease

This study investigates the intricate interplay between environmental pollutants and exosomes, shedding light on a novel paradigm in environmental health and disease. Cellular stress, induced by environmental toxicants or disease, significantly impacts the production and composition of exosomes, crucial mediators of intercellular communication. The heat shock response (HSR) and unfolded protein response (UPR) pathways, activated during cellular stress, profoundly influence exosome generation, cargo sorting, and function, shaping intercellular communication and stress responses. Environmental pollutants, particularly lipophilic ones, directly interact with exosome lipid bilayers, potentially affecting membrane stability, release, and cellular uptake. The study reveals that exposure to environmental contaminants induces significant changes in exosomal proteins, miRNAs, and lipids, impacting cellular function and health. Understanding the impact of environmental pollutants on exosomal cargo holds promise for biomarkers of exposure, enabling non-invasive sample collection and real-time insights into ongoing cellular responses. This research explores the potential of exosomal biomarkers for early detection of health effects, assessing treatment efficacy, and population-wide screening. Overcoming challenges requires advanced isolation techniques, standardized protocols, and machine learning for data analysis. Integration with omics technologies enhances comprehensive molecular analysis, offering a holistic understanding of the complex regulatory network influenced by environmental pollutants. The study underscores the capability of exosomes in circulation as promising biomarkers for assessing environmental exposure and systemic health effects, contributing to advancements in environmental health research and disease prevention.

Exosomal derived miR-1246 from hydroquinone-transformed cells drives S phase accumulation arrest by targeting cyclin G2 in TK6 cells

BACKGROUND

Hydroquinone (HQ), a major metabolite of benzene and known hematotoxic carcinogen. MicroRNA 1246 (miR-1246), an oncogene, regulates target genes in carcinogenesis including leukemia. This study investigates the impact of exosomal derived miR-1246 from HQ-transformed (HQ19) cells on cell-to-cell communication in recipient TK6 cells.

METHODS

RNA sequencing was used to identify differentially expressed exosomal miRNAs in HQ19 cells and its phosphate buffered solution control cells (PBS19), which were then confirmed using qRT-PCR. The impact of exosomal miR-1246 derived from HQ-transformed cells on cell cycle distribution was investigated in recipient TK6 cells.

RESULTS

RNA sequencing analysis revealed that 34 exosomal miRNAs were upregulated and 158 miRNAs were downregulated in HQ19 cells compared with PBS19 cells. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses predicted that their targets are enriched in cancer development-related pathways, such as MAPK signaling, microRNAs in cancer, apoptosis, PI3K-Akt signaling, cell cycle, Ras signaling, and Chronic myeloid leukemia. Eleven miRNAs were confirmed to have differential expression through qRT-PCR, with 6 upregulated (miR-140-3p, miR-551b-3p, miR-7-5p, miR-1290, miR-92a-3p, and miR-1246) and 5 downregulated (miR-183-5p, miR-26a-5p, miR-30c-5p, miR-205-5p, and miR-99b-3p). Among these, miR-1246 exhibited the highest expression level. HQ exposure resulted in a concentration-dependent increase in miR-1246 levels and decrease Cyclin G2 (CCNG2) levels in TK6 cells. Similarly, exosomes from HQ19 exhibited similar effects as HQ exposure. Dual luciferase reporter gene assays indicated that miR-1246 could band to CCNG2. After HQ exposure, exosomal miR-1246 induced cell cycle arrest at the S phase, elevating the expression of genes like pRb, E2F1, and Cyclin D1 associated with S phase checkpoint. However, silencing miR-1246 caused G2/M-phase arrest.

CONCLUSION

HQ-transformed cells' exosomal miR-1246 targets CCNG2, regulating TK6 cell cycle arrest, highlighting its potential as a biomarker for HQ-induced malignant transformation.

Periconceptional and Prenatal Exposure to Metals and Extracellular Vesicle and Particle miRNAs in Human Milk: A Pilot Study

Human milk is a rich source of microRNAs (miRNAs), which can be transported by extracellular vesicles and particles (EVPs) and are hypothesized to contribute to maternal-offspring communication and child development. Environmental contaminant impacts on EVP miRNAs in human milk are largely unknown. In a pilot study of 54 mother-child pairs from the New Hampshire Birth Cohort Study, we examined relationships between five metals (arsenic, lead, manganese, mercury, and selenium) measured in maternal toenail clippings, reflecting exposures during the periconceptional and prenatal periods, and EVP miRNA levels in human milk. 798 miRNAs were profiled using the NanoString nCounter platform; 200 miRNAs were widely detectable and retained for downstream analyses. Metal-miRNA associations were evaluated using covariate-adjusted robust linear regression models. Arsenic exposure during the periconceptional and prenatal periods was associated with lower total miRNA content in human milk EVPs (PBonferroni < 0.05). When evaluating miRNAs individually, 13 miRNAs were inversely associated with arsenic exposure, two in the periconceptional period and 11 in the prenatal period (PBonferroni < 0.05). Other metal-miRNA associations were not statistically significant after multiple testing correction (PBonferroni ≥ 0.05). Many of the arsenic-associated miRNAs are involved in lactation and have anti-inflammatory properties in the intestine and tumor suppressive functions in breast cells. Our findings raise the possibility that periconceptional and prenatal arsenic exposure may reduce levels of multiple miRNAs in human milk EVPs. However, larger confirmatory studies, which can apply environmental mixture approaches, evaluate potential effect modifiers of these relationships, and examine possible downstream consequences for maternal and child health and breastfeeding outcomes, are needed.

The Role of microRNAs in Arsenic-Induced Human Diseases: A Review

MicroRNAs (miRNAs) are noncoding RNAs with 20-22 nucleotides, which are encoded by endogenous genes and are capable of targeting the majority of human mRNAs. Arsenic is regarded as a human carcinogen, which can lead to many adverse health effects including diabetes, skin lesions, kidney disease, neurological impairment, male reproductive injury, and cardiovascular disease (CVD) such as cardiac arrhythmias, ischemic heart failure, and endothelial dysfunction. miRNAs can act as tumor suppressors and oncogenes via directly targeting oncogenes or tumor suppressors. Recently, miRNA dysregulation was considered to be an important mechanism of arsenic-induced human diseases and a potential biomarker to predict the diseases caused by arsenic exposure. Endogenic miRNAs such as miR-21, the miR-200 family, miR-155, and the let-7 family are involved in arsenic-induced human disease by inducing translational repression or RNA degradation and influencing multiple pathways, including mTOR/Arg 1, HIF-1α/VEGF, AKT, c-Myc, MAPK, Wnt, and PI3K pathways. Additionally, exogenous miRNAs derived from plants, such as miR-34a, miR-159, miR-2911, miR-159a, miR-156c, miR-168, etc., among others, can be transported from blood to specific tissue/organ systems in vivo. These exogenous miRNAs might be critical players in the treatment of human diseases by regulating host gene expression. This review summarizes the regulatory mechanisms of miRNAs in arsenic-induced human diseases, including cancers, CVD, and other human diseases. These special miRNAs could serve as potential biomarkers in the management and treatment of human diseases linked to arsenic exposure. Finally, the protective action of exogenous miRNAs, including antitumor, anti-inflammatory, anti-CVD, antioxidant stress, and antivirus are described.

Effect of environmental exposures on cancer risk: Emerging role of non-coding RNA shuttled by extracellular vesicles

Environmental and lifestyle exposures have a huge impact on cancer risk; nevertheless, the biological mechanisms underlying this association remain poorly understood. Extracellular vesicles (EVs) are membrane-enclosed particles actively released by all living cells, which play a key role in intercellular communication. EVs transport a variegate cargo of biomolecules, including non-coding RNA (ncRNA), which are well-known regulators of gene expression. Once delivered to recipient cells, EV-borne ncRNAs modulate a plethora of cancer-related biological processes, including cell proliferation, differentiation, and motility. In addition, the ncRNA content of EVs can be altered in response to outer stimuli. Such changes can occur either as an active attempt to adapt to the changing environment or as an uncontrolled consequence of cell homeostasis loss. In either case, such environmentally-driven alterations in EV ncRNA might affect the complex crosstalk between malignant cells and the tumor microenvironment, thus modulating the risk of cancer initiation and progression. In this review, we summarize the current knowledge about EV ncRNAs at the interface between environmental and lifestyle determinants and cancer. In particular, we focus on the effect of smoking, air and water pollution, diet, exercise, and electromagnetic radiation. In addition, we have conducted a bioinformatic analysis to investigate the biological functions of the genes targeted by environmentally-regulated EV microRNAs. Overall, we draw a comprehensive picture of the role of EV ncRNA at the interface between external factors and cancer, which could be of great interest to the development of novel strategies for cancer prevention, diagnosis, and therapy.

Molecular mechanisms of environmental exposures and human disease

A substantial proportion of disease risk for common complex disorders is attributable to environmental exposures and pollutants. An appreciation of how environmental pollutants act on our cells to produce deleterious health effects has led to advances in our understanding of the molecular mechanisms underlying the pathogenesis of chronic diseases, including cancer and cardiovascular, neurodegenerative and respiratory diseases. Here, we discuss emerging research on the interplay of environmental pollutants with the human genome and epigenome. We review evidence showing the environmental impact on gene expression through epigenetic modifications, including DNA methylation, histone modification and non-coding RNAs. We also highlight recent studies that evaluate recently discovered molecular processes through which the environment can exert its effects, including extracellular vesicles, the epitranscriptome and the mitochondrial genome. Finally, we discuss current challenges when studying the exposome - the cumulative measure of environmental influences over the lifespan - and its integration into future environmental health research.

The impact of environmental contaminants on extracellular vesicles and their key molecular regulators: A literature and database-driven review

Exposure to environmental chemicals is now well recognized as a significant factor contributing to the global burden of disease; however, there remain critical gaps in understanding the types of biological mechanisms that link environmental chemicals to adverse health outcomes. One type of mechanism that remains understudied involves extracellular vesicles (EVs), representing small cell-derived particles capable of carrying molecular signals such as RNAs, miRNAs, proteins, lipids, and chemicals through biological fluids and imparting beneficial, neutral, or negative effects on target cells. In fact, evidence is just now starting to grow that supports the role of EVs in various disease etiologies. This review aims to (1) Provide a landscape of the current understanding of the functional relationship between EVs and environmental chemicals; (2) Summarize current knowledge of EV regulatory processes including production, packaging, and release; and (3) Conduct a database-driven analysis of known chemical-gene interactions to predict and prioritize environmentally relevant chemicals that may impact EV regulatory genes and thus EV regulatory processes. This approach to predicting environmentally relevant chemicals that may alter EVs provides a novel method for evidence-based hypothesis generation for future studies evaluating the link between environmental exposures and EVs.

The Role and Application of Exosomes and Their Cargos in Reproductive Diseases: A Systematic Review

In recent years, the incidence of the reproductive diseases is increasing year-by-year, leading to abortion or fetal arrest, which seriously affects the reproductive health of human beings and the reproductive efficiency of animals. Exosomes are phospholipid bilayer vesicles that are widely distributed in living organisms and released by the cells of various organs and tissues. Exosomes contain proteins, RNA, lipids, and other components and are important carriers of information transfer between cells, which play a variety of physiological and pathological regulatory functions. More and more studies have found that exosomes and their connotations play an important role in the diagnosis, prognosis and treatment of diseases. A systematic review was conducted in this manuscript and then highlights our knowledge about the diagnostic and therapeutic applications of exosomes to reproductive diseases, such as polycystic ovary syndrome (PCOS), endometriosis, premature ovarian failure (POF), preeclampsia, polycystic, endometrial cancer, cervical cancer, ovarian cancer, and prostate gland cancer.

JAK2/STAT3 in role of arsenic-induced cell proliferation: a systematic review and meta-analysis

OBJECTIVES

Malignant cell proliferation is one of the important mechanisms of arsenic poisoning. A large number of studies have shown that STAT3 plays an important role in cell malignant proliferation, but there are still many contradictions in the effect of arsenic on JAK2/STAT3. This study aims to explore the role of JAK2/STAT3 in arsenic-induced cell proliferation.

METHODS

By taking normal cells as the research object and using Standard Mean Difference (SMD) as the effect size, meta-analysis was used to explore the effect of arsenic on JAK2/STAT3. Then, the dose-effect Meta was used to further clarify the dose-effect relationship of arsenic on JAK2/STAT3.

RESULTS

Through meta-analysis, this study found that arsenic could promote the phosphorylation of STAT3 (SMD=4.21, 95%CI [1.05, 7.37]), and increase IL-6 and p-JAK2, Vimentin, VEGF expression levels, thereby inducing malignant cell proliferation. In addition, this study also found that arsenic exposure dose (<5 μmol m^-3), time(<24 h) and cell type were important sources of heterogeneity in the process of exploring the effects of arsenic on p-STAT3, IL-6 and p-JAK2. Dose-effect relationship meta-analysis results showed that arsenic exposure significantly increased the expression level of IL-6. When the arsenic exposure concentration was less than 7 μmol m^-3, the expression level of p-JAK2 upregulated significantly as the arsenic exposure concentration gradually increasing. Moreover, the expression level of p-STAT3 elevated significantly with the gradual increase of the arsenic concentration under 5 μmol m^-3 of arsenic exposure, but the expression level of p-STAT3 gradually decreases when the concentration is greater than 5 μmol m^-3.

CONCLUSIONS

Exposure to low dose of arsenic could promote the expression of JAK2/STAT3 and induce the malignant proliferation of cells through upregulating IL-6, and there was dose-effect relationship among them.

Environmental Exposures and Extracellular Vesicles: Indicators of Systemic Effects and Human Disease

PURPOSE OF REVIEW

Environmental pollutants contribute to the pathogenesis of numerous diseases including chronic cardiovascular, respiratory, and neurodegenerative diseases, among others. Emerging evidence suggests that extracellular vesicles (EVs) may mediate the association of environmental exposures with chronic diseases. The purpose of this review is to describe the impact of common environmental exposures on EVs and their role in linking environmental pollutants to the pathogenesis of chronic systemic diseases.

RECENT FINDINGS

Common environmental pollutants including particulate matter, tobacco smoke, and chemical pollutants trigger the release of EVs from multiple systems in the body. Existing research has focused primarily on air pollutants, which alter EV production and release in the lungs and systemic circulation. Air pollutants also impact the selective loading of EV cargo including microRNA and proteins, which modify the cellular function in recipient cells. As a result, pollutant-induced EVs often contribute to a pro-inflammatory and pro-thrombotic milieu, which increases the risk of pollutant-related diseases including obstructive lung diseases, cardiovascular disease, neurodegenerative diseases, and lung cancer. Common environmental exposures are associated with multifaceted changes in EVs that lead to functional alterations in recipient cells and contribute to the pathogenesis of chronic systemic diseases. EVs may represent emerging targets for the prevention and treatment of diseases that stem from environmental exposures. However, novel research is required to expand our knowledge of the biological action of EV cargo, elucidate determinants of EV release, and fully understand the impact of environmental pollutants on human health.

Indirect mediators of systemic health outcomes following nanoparticle inhalation exposure

The growing field of nanoscience has shed light on the wide diversity of natural and anthropogenic sources of nano-scale particulates, raising concern as to their impacts on human health. Inhalation is the most robust route of entry, with nanoparticles (NPs) evading mucociliary clearance and depositing deep into the alveolar region. Yet, impacts from inhaled NPs are evident far outside the lung, particularly on the cardiovascular system and highly vascularized organs like the brain. Peripheral effects are partly explained by the translocation of some NPs from the lung into the circulation; however, other NPs largely confined to the lung are still accompanied by systemic outcomes. Omic research has only just begun to inform on the complex myriad of molecules released from the lung to the blood as byproducts of pulmonary pathology. These indirect mediators are diverse in their molecular make-up and activity in the periphery. The present review examines systemic outcomes attributed to pulmonary NP exposure and what is known about indirect pathological mediators released from the lung into the circulation. Further focus was directed to outcomes in the brain, a highly vascularized region susceptible to acute and longer-term outcomes. Findings here support the need for big-data toxicological studies to understand what drives these health outcomes and better predict, circumvent, and treat the potential health impacts arising from NP exposure scenarios.

Tanshinone IIA-regulation of IL-6 antagonizes PM2 .5 -induced proliferation of human bronchial epithelial cells via a STAT3/miR-21 reciprocal loop

Particulate matter 2.5 (PM_2.5 ), a component of atmospheric particulate matter, leads to changes in gene expression and cellular functions. Epidemiological evidence confirms that PM_2.5 has a positive correlation with lung injury. However, the molecular mechanisms involved remain poorly understood, and preventive methods are needed. In the present study, with human bronchial epithelial (HBE) cells in culture, we showed that low concentrations of PM_2.5 resulted in acceleration of the G1/S transition and cell proliferation. Consistent with these effects, expression of the pro-inflammatory factor interleukin-6 (IL-6) was elevated in HBE cells exposed to PM_2.5 . Accordingly, signal transducer and activator of transcription 3 (STAT3) was activated, which down-regulated expression of cyclin D1. In addition, PM_2.5 exposure led to higher levels of miR-21, and there was a reciprocal loop between miR-21 and STAT3. For HBE cells, tanshinone IIA (Tan IIA) reversed the PM_2.5 -induced cell cycle alteration and cell proliferation, and reduced the expression of cytokines (IL-6, STAT3, and miR-21). These results show that, for HBE cells, Tan IIA attenuates the PM_2.5 -induced G1/S alteration and cell proliferation, and indicate that it has potential clinical application for PM_2.5 -induced respiratory injuries.

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

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

Urinary metals and maternal circulating extracellular vesicle microRNA in the MADRES pregnancy cohort

Exposure to metals increases risk for pregnancy complications. Extracellular vesicle (EV) miRNA contribute to maternal-foetal communication and are dysregulated in pregnancy complications. However, metal impacts on maternal circulating EV miRNA during pregnancy are unknown. Our objective was to investigate the impact of multiple metal exposures on EV miRNA in maternal circulation during pregnancy in the MADRES Study. Associations between urinary concentrations of nine metals and 106 EV miRNA in maternal plasma during pregnancy were investigated using robust linear regression (N = 231). Primary analyses focused on metal-miRNA associations in early pregnancy (median: 12.3 weeks gestation). In secondary analyses, we investigated associations with late pregnancy miRNA counts (median: 31.8 weeks gestation) in a subset of participants (N = 184) with paired measures. MiRNA associated with three or more metals (P_FDR<0.05) were further investigated using Bayesian Kernel Machine Regression (BKMR), an environmental mixture method. Thirty-five miRNA were associated (P_FDR<0.05) with at least one metal in early pregnancy. One association (an inverse association between cobalt and miR-150-5p) remained statistically significant when evaluating late pregnancy miRNA counts. Eight miRNA (miR-302b-3p, miR-199a-5p, miR-188-5p, miR-138-5p, miR-212-3p, miR-608, miR-1272, miR-19b-3p) were associated with three metals (barium, mercury, and thallium) in early pregnancy, and their predicted target genes were enriched in pathways important for placental development. Results were consistent when using BKMR. Early pregnancy exposure to barium, mercury, and thallium may have short-term impacts on a common set of EV miRNA which target pathways important for placental development.

Extracellular vesicle interactions with the external and internal exposome in mediating carcinogenesis

The influence of environmental factors on an individual, from conception onwards, is defined as the exposome. It can be categorized into the external exposome, which includes external factors such as air pollution, chemical contaminants, and diet, and the internal exposome, which is unique to an individual, and involves age, physiology, and their genetic profile. The effect of external exposures on the internal exposome, or genetic profile, can be determined through omics analyses. However, this is often compromised due to low sample quantity and cost. Therefore, identification of other factors that can provide an insight into the cellular profile of an individual, provides an exciting avenue, and an emerging field is that of extracellular vesicles (EVs). Recently, our understanding of how cells can communicate with each other has shifted to recognise the role of EVs. EVs are secreted by all living cells, and have been identified in all biological fluids studied so far. They transport bioactive molecules (e.g., proteins, miRNAs, and DNA), and their release can be regulated by the cellular microenvironment. Analysis of EVs in respond to environmental factors might provide novel insights into the role of tumour EVs in carcinogenesis. Not only will EVs give some insight into the tumour cells themselves but they will also provide a better understanding of how cells communicate with one another, contributing to cancer progression. Moreover, characterising the content and functions of tumour-derived EVs has the potential to overcome the current challenges to improve cancer patient outcomes. For example, the identification of EVs targets for therapeutic interventions and tumour EVs biomarkers could facilitate the development of early screening for several cancers. The aim of this review, thus, is to discuss the overall role of EVs in response to the various external and internal signals in cancer. We will specifically highlight the biogenesis, secretion, and content of EVs in response to oncogenic transformation and metabolic regulators in cancer.

Crosstalk between Environmental Inflammatory Stimuli and Non-Coding RNA in Cancer Occurrence and Development

Simple Summary

Increasing evidence has indicated that chronic inflammatory processes have an influence on tumor occurrence and all stages of tumor development. A dramatic increase of studies into non-coding RNAs (ncRNAs) biology has shown that ncRNAs act as oncogenic drivers and tumor suppressors in various inflammation-induced cancers. Thus, this complex network of inflammation-associated cancers and ncRNAs offers targets for prevention from the malignant transformation from inflammation and treatment of malignant diseases.

Abstract

There is a clear relationship between inflammatory response and different stages of tumor development. Common inflammation-related carcinogens include viruses, bacteria, and environmental mutagens, such as air pollutants, toxic metals, and ultraviolet light. The expression pattern of ncRNA changes in a variety of disease conditions, including inflammation and cancer. Non-coding RNAs (ncRNAs) have a causative role in enhancing inflammatory stimulation and evading immune responses, which are particularly important in persistent pathogen infection and inflammation-to-cancer transformation. In this review, we investigated the mechanism of ncRNA expression imbalance in inflammation-related cancers. A better understanding of the function of inflammation-associated ncRNAs may help to reveal the potential of ncRNAs as a new therapeutic strategy.

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.

MicroRNA and ER stress in cancer

The development of biological technologies in genomics, proteomics, and bioinformatics has led to the identification and characterization of the complete set of coding genes and their roles in various cellular pathways in cancer. Nevertheless, the cellular pathways have not been fully figured out like a jigsaw puzzle with missing pieces. The discovery of noncoding RNAs including microRNAs (miRNAs) has provided the missing pieces of the cellular pathways. Likewise, miRNAs have settled many questions of inexplicable patches in the endoplasmic reticulum (ER) stress pathways. The ER stress-caused pathways typified by the unfolded protein response (UPR) are pivotal processes for cellular homeostasis and survival, rectifying uncontrolled proteostasis and determining the cell fate. Although various factors and pathways have been studied and characterized, the understanding of the ER stress requires more wedges to fill the cracks of knowledge about the ER stress pathways. Moreover, the roles of the ER stress and UPR are still controversial in cancer despite their strong potential to promote cancer. The noncoding RNAs, in particular, miRNAs aid in a better understanding of the ER stress and its role in cancer. In this review, miRNAs that are the more-investigated subtype of noncoding RNAs are focused on the interpretation of the ER stress in cancer, following the introduction of miRNA and ER stress.

Inhibition of miR-155 alleviates sepsis-induced inflammation and intestinal barrier dysfunction by inactivating NF-κB signaling

MicroRNA-155 (miR-155) is implicated in the pathological processes of sepsis. However, the function and regulatory mechanism of miR-155 in sepsis-induced inflammation and intestinal barrier dysfunction remain unknown. In this study, mouse models of sepsis were established by caecal ligation and puncture (CLP). To reduce miR-155 expression, the mice were injected for three consecutive days with an miR-155 inhibitor (80 mg/kg) before CLP. The serum DAO concentration was measured by ELISA, and histological changes in the intestine were identified by H&E staining 24 h after CLP. FITC-dextran assays were used to evaluate intestinal permeability. MiR-155 gene expression was evaluated with RT-PCR, and relative protein expression was assessed by Western blotting. NCM460 cells were transfected with an miR-155 mimic/miR-155 inhibitor or pretreated with an NF-κB inhibitor before LPS treatment, and the cytokines levels, miR-155 gene expression and relative protein expression were measured. Sepsis increased miR-155, DAO and FITC-dextran levels and reduced Occludin and ZO-1 expression. Mice injected with the miR-155 inhibitor recovered from the damages. Transfection of NCM460 cells with the miR-155 mimic elevated the NF-κB (P65) and p-NF-κB (p-P65) localization and expression in the nucleus, which was reversed by the miR-155 inhibitor. Pretreatment with an NF-κB inhibitor suppressed inflammation, improved cell permeability to FITC-dextran and increased Occludin and ZO-1 levels. Transfection with the miR-155 inhibitor decreased TNF-α and IL-6 levels, reduced cell permeability to FITC-dextran and increased ZO-1 and Occludin expression. The effects induced by transfection with the miR-155 mimic, including elevated TNF-α and IL-6 levels, hyperpermeability to FITC-dextran and reduced ZO-1 and Occludin expression, were partly rescued by pretreatment with the NF-κB inhibitor. These findings reveal that the miR-155 inhibitor alleviates inflammation and intestinal barrier dysfunction by inactivating NF-κB signaling during sepsis.

Eutopic stromal cells of endometriosis promote neuroangiogenesis via exosome pathway†

Endometriosis is a common multifactorial gynecological disorder defined as the proliferation of endometrial tissue outside of the uterine cavity. Neuroangiogenesis (co-recruitment of nerves and blood vessels) is believed to play an integral part in the establishment and growth of endometriotic lesions. We hypothesized that exosomes derived from abnormal endometrium may serve as the second identifier of endometriosis and play an important role in the development of endometriosis by regulating neuroangiogenesis. Primary human endometrial stromal cells (ESCs) were isolated from eutopic endometrium (EmESC, n = 22) with endometriosis and normal endometrium (CoESC, n = 6). Exosomes were isolated from ESCs using the "standard" ultracentrifugation method, and the characterization of exosomes was identified through transmission electron microscopy, nanoparticle tracking analysis, and western blot. The role of exosomes in regulating neuroangiogenesis was determined through in vitro tube formation assay, neurite outgrowth assay, and dorsal root ganglion (DRG) neuron apoptosis analysis. The data showed that EmESCs could secrete exosomes with a diameter of approximately 100 nm and a biconcave morphological feature; they were internalized by human umbilical vein endothelial cells and DRG neurons and enhanced neuroangiogenic effects. We further validated the role of exosomes through blocking experiments. We found that when the exosome secretion was blocked, the pro-neuroangiogenesis effects were decreased. In conclusion, these data suggested that exosomes may play a key role in endometriosis by promoting neuroangiogenesis.

Extracellular vesicles in toxicological studies: key roles in communication between environmental stress and adverse outcomes

External stressors, especially environmental toxicants can disturb biological homeostasis and thus lead to adverse health effects. However, there is limited understanding of how cells directly exposed to stressors transmit the signals to cells indirectly in contact with stressors. Extracellular vesicles (EVs) are receiving increasing attention as signal transductors between various types of cells in organisms. Cargo in EVs, including RNAs, proteins, lipids, and other signal molecules can be transferred between cells and become critical determining factors of intercellular communication. EVs can be a powerful mediator of environmental stimuli. It has been shown that external stressors reshape the secretion of EVs, modify the composition of EVs, and thus influence the mediating function of EVs. These abnormal EVs can lead to dysfunction of recipient cells, and even the pathogenesis of diseases. In this review, we first summarized current knowledge about the responses of EVs to external stimuli, including chemicals and chemical mixtures. Then we explained how these altered EVs regulate signal pathways in recipient cells, thus mediating physio-pathological responses in detail. The most up-to-date evidence from molecular, cellular, animal and human levels was synthesized to systematically address the mediating roles of EVs. EVs can be regarded as a bridge to link external stressors and internal response. Further toxicological and molecular epidemiological studies are expected to provide further insight into the roles of EVs in toxicology. The gaps in the engulfment of toxicants into EVs are listed as the priority to be solved in future studies.

Exosomes as Mediators of Chemical-Induced Toxicity

PURPOSE OF REVIEW

This review provides information regarding how exosomes may contribute to environmental chemical-induced pathogenesis of chronic diseases. In connecting exosome biology to environmental toxicology and disease pathogenesis, we address vital questions regarding what constitutes exosomal cargo, how toxicants influence exosomal cargo, and how environmental stimuli influence exosomal physiological and pathological functions.

RECENT FINDINGS

Recent studies in the field demonstrate that exosomal cargo changes depending on external stimuli, which has consequences for the microenvironment of recipient cells. Based on recent findings, it is evident that exosomal cargo comprises various biological molecules including proteins, nucleic acids, and lipid molecules. Misfolded proteins and miRNA are examples of exosomal cargo molecules that can be altered by toxicants, ultimately changing the microenvironment of recipient cells in ways that are conducive to pathological processes. It will be crucial to map out the key signaling pathways that toxicants target to modulate exosomal cargo and their release.

Exosomal hsa-miR-21-5p derived from growth hormone-secreting pituitary adenoma promotes abnormal bone formation in acromegaly

Growth hormone-secreting pituitary adenoma (GHPA), a benign endocrine tumor located in the base of the skull, results in acromegaly. In addition to the mass effect of the tumor itself in the sellar region, GHPA can lead to the overgrowth of almost every organ. Previous findings indicated that the processes underlying acromegaly were partly attributable to hyperactivity of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis. However, the mechanisms driving this syndrome remains largely unknown. Additionally, the roles of GHPA-derived exosomes, which contain functional microRNAs and proteins that manipulate target cell proliferation and differentiation in distal extremities, are also unknown. In this study, we demonstrated that GHPA exosomes promote bone formation in vitro and trabecula number in vivo. The mechanism of increased trabecula formation may be attributable to GHPA exosome-induced osteoblast proliferation via increased cell viability and DNA replication. We further discovered that exosomal hsa-miR-21-5p plays a distinct role from the GH/IGF-1 axis in these processes. Accordingly, the results of this study provide a novel mechanism whereby GHPA influences distal extremities and a new perspective for treating GHPA.

The Role of Exosomes in Diseases Related to Infertility

Exosomes, small extracellular vesicles with diameters of 40-100nm, are generated through the fusion of multivessel with plasma membrane and secreted by a variety of living cells. Exosomes contain lipid bilayer membrane and releasable functionally active proteins, mRNA and microRNAs (miRNAs). This article reviews the latest progress of researches on exosomes in diseases that lead to infertility.

Plasma exosome-encapsulated microRNA-21 and microRNA-92a are promising biomarkers for the prediction of peritoneal recurrence in patients with gastric cancer

In patients with gastric cancer (GC), peritoneal recurrence is a common risk and associated with poor prognosis. A novel biomarker for the prediction of high-risk peritoneal recurrence in patients with GC is desirable. The present study investigated the effectiveness of exosome-encapsulated microRNAs (ex-miRNAs) as minimally invasive biomarkers in patients with GC that received curative surgery. Recurrence-specific ex-miRNAs were selected following comparison of miRNA microarray data from patients with TNM stage II GC with peritoneal recurrence (n=3) and without peritoneal recurrence following curative surgery (n=3), and three healthy volunteers. In this analysis, exosome-encapsulated miRNA-21 (ex-miR-21) and exosomal miR-92a (ex-miR-92a) exhibited the greatest alterations in expression patterns. Using plasma exosome samples collected from another 129 patients with stage II and III GC, the present study investigated the potential value of ex-miR-21 and ex-miR-92a as biomarkers. Ex-miRNA levels were measured using TaqMan miRNA assays. Ex-miR-21 levels were significantly higher and ex-miR-92a levels were significantly lower in samples from patients with GC compared with healthy controls. The overall survival (OS) and peritoneal recurrence-free survival (PRFS) were poorer in stage II and III patients with high ex-miR-21 levels than in patients with low miR-21 levels. OS and PRFS of stage II and III patients with low ex-miR92a levels were significantly worse than those with high ex-miR92a levels. Cox multivariate analyses indicated that ex-miR-21 and ex-miR-92a were independent prognostic factors for OS and PRFS in stage II and III GC. A negative correlation was detected between expression levels of miR-21 and programmed cell death protein 4 mRNA, and miR-92a and prostaglandin E receptor 4 mRNA. Therefore, ex-miR-21 and ex-miR-92a may function as effective and minimally invasive biomarkers for the prediction of peritoneal recurrence and the prognosis of patients with stage II/III GC.

microRNA-21-5p dysregulation in exosomes derived from heart failure patients impairs regenerative potential

Exosomes, as functional paracrine units of therapeutic cells, can partially reproduce the reparative properties of their parental cells. The constitution of exosomes, as well as their biological activity, largely depends on the cells that secrete them. We isolated exosomes from explant-derived cardiac stromal cells from patients with heart failure (FEXO) or from normal donor hearts (NEXO) and compared their regenerative activities in vitro and in vivo. Patients in the FEXO group exhibited an impaired ability to promote endothelial tube formation and cardiomyocyte proliferation in vitro. Intramyocardial injection of NEXO resulted in structural and functional improvements in a murine model of acute myocardial infarction. In contrast, FEXO therapy exacerbated cardiac function and left ventricular remodeling. microRNA array and PCR analysis revealed dysregulation of miR-21-5p in FEXO. Restoring miR-21-5p expression rescued FEXO's reparative function, whereas blunting miR-21-5p expression in NEXO diminished its therapeutic benefits. Further mechanistic studies revealed that miR-21-5p augmented Akt kinase activity through the inhibition of phosphatase and tensin homolog. Taken together, the heart failure pathological condition altered the miR cargos of cardiac-derived exosomes and impaired their regenerative activities. miR-21-5p contributes to exosome-mediated heart repair by enhancing angiogenesis and cardiomyocyte survival through the phosphatase and tensin homolog/Akt pathway.

Adipose-derived mesenchymal stem cell exosomes: a novel pathway for tissues repair

The well-characterized curative effect of transplanted mesenchymal stem cells has been mainly attributed to their homing and subsequent differentiation for the repair and regeneration of damaged tissue. Adipose-derived mesenchymal stem cells (ADMSCs) are not only multipotent and plastic, but also abundant as they can be easily harvested with minimally invasive surgical techniques. This makes ADMSCs conducive for clinical applications. Recently, the secretory function of ADMSCs has been regarded as the primary mediator of MSC-based therapy. Exosomes are one kind of small cell extracellular membrane vesicles, which are primarily used to deliver cell-specific proteins, as well as nucleic acids secreted by various cell types. This review will introduce and characterize exosomes-derived ADMSCs (ADMSCs-Exo) and look at new therapies and prospective, including the limitations and outlook for therapeutic strategy. We will describe the latest research progress on myocardial repair, neuroprotection and neurotrophic effects, hepatic repair, renal repair, cutaneous repair, regeneration and other aspects using these cells.

MicroRNAs and their role in environmental chemical carcinogenesis

MicroRNAs (miRNAs) are a class of small, noncoding RNA species that play crucial roles across many biological processes and in the pathogenesis of major diseases, including cancer. Recent studies suggest that the expression of miRNA is altered by certain environmental chemicals, including metals, organic pollutants, cigarette smoke, pesticides and carcinogenic drugs. In addition, extensive studies have indicated the existence and importance of miRNA in different cancers, suggesting that cancer-related miRNAs could serve as potential markers for chemically induced cancers. The altered expression of miRNA was considered to be a vital pathogenic role in xenobiotic-induced cancer development. However, the significance of miRNA in the etiology of cancer and the exact mechanisms by which environmental factors alter miRNA expression remain relatively unexplored. Hence, understanding the interaction of miRNAs with environmental chemicals will provide important information on mechanisms underlying the pathogenesis of chemically induced cancers, and effectively diagnose and treat human cancers resulting from chronic or acute carcinogen exposure. This study presents the current evidence that the miRNA deregulation induced by various chemical carcinogens, different cancers caused by environmental carcinogens and the potentially related genes in the onset or progression of cancer. For each carcinogen, the specifically expressed miRNA may be considered as the early biomarkers of the cancer process. In this review, we also summarize various target genes of the altered miRNA, oncogenes or anti-oncogenes, and the existing evidence regarding the gene regulation mechanisms of cancer caused by environmentally induced miRNA alteration. The future perspective of miRNA may become attractive targets for the diagnosis and treatment of carcinogen-induced cancer.

Exosome-transmitted long non-coding RNA PTENP1 suppresses bladder cancer progression

Background

Extracellular communication within the tumor microenvironment plays a critical role in tumor progression. Although exosomes can package into long non-coding RNAs (lncRNAs) to mediate extracellular communication, the role of exosomal lncRNA PTENP1 in bladder cancer (BC) remains unclear.

Method

We detected PTENP1 expression between patients with BC and healthy controls; the expression occurred in tissues and exosomes from plasma. We assessed the diagnostic accuracy by the receiver operating characteristic curve (ROC) and the area under curve (AUC). Cell phenotypes and animal experiments were performed to determine the effect of exosomal PTENP1.

Results

PTENP1 was significantly reduced in BC tissues and in exosomes from plasma of patients with BC (P < 0.05). We found that PTENP1 was mainly wrapped by exosomes. Exosomal PTENP1 could distinguish patients with BC from healthy controls (AUC = 0.743; 95% confidence interval (CI) = 0.645–0.840). Normal cells secreted exosomal PTENP1 and transmitted it to BC cells, thus inhibiting the biological malignant behavior of BC cells by increasing cell apoptosis and reducing the ability to invade and migrate (P < 0.05). Exosomal PTENP1 could suppress tumor growth in vivo. Furthermore, exosomal PTENP1 mediated the expression of PTEN by competitively binding to microRNA-17.

Conclusion

Exosomal PTENP1 is a promising novel biomarker that can be used for the clinical detection of BC. Exosomes derived from normal cells transfer PTENP1 to BC cells, which reduce the progression of BC both in vitro and in vivo and suggest that exosomal PTENP1 participates in normal-cell-to-bladder-cell communication during the carcinogenesis of BC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0880-3) contains supplementary material, which is available to authorized users.

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.

Cardiosphere-Derived Cells and Ischemic Heart Failure

After a myocardial infarction, heart tissue becomes irreversibly damaged, leading to scar formation and inevitably ischemic heart failure. Of the many available interventions after a myocardial infarction, such as percutaneous intervention or pharmacological optimization, none can reverse the ischemic insult on the heart and restore cardiac function. Thus, the only available cure for patients with scarred myocardium is allogeneic heart transplantation, which comes with extensive costs, risks, and complications. However, multiple studies have shown that the heart is, in fact, not an end-stage organ and that there are endogenous mechanisms in place that have the potential to spark regeneration. Stem cell therapy has emerged as a potential tool to tap into and activate this endogenous framework. Particularly promising are stem cells derived from cardiac tissue itself, referred to as cardiosphere-derived cells (CDCs). CDCs can be extracted and isolated from the patient's myocardium and then administered by intramyocardial injection or intracoronary infusion. After early success in the animal model, multiple clinical trials have demonstrated the safety and efficacy of autologous CDC therapy in humans. Clinical trials with allogeneic CDCs showed early promising results and pose a potential "off-the-shelf" therapy for patients in the acute setting after a myocardial infarction. The mechanism responsible for CDC-induced cardiac regeneration seems to be a combination of triggering native cardiomyocyte proliferation and recruitment of endogenous progenitor cells, which most prominently occurs via paracrine effects. A further understanding of the mediators involved in paracrine signaling can help with the development of a stem cell-free therapy, with all the benefits and none of the associated complications.

Exosomes in Toxicology: Relevance to Chemical Exposure and Pathogenesis of Environmentally Linked Diseases

Chronic exposure to environmental toxins has been known to initiate or aggravate various neurological disorders, carcinomas and other adverse health effects. Uptake by naïve cells of pathogenic factors such as danger-associated molecules, mRNAs, miRNAs or aggregated proteins leads to disruption in cellular homeostasis further resulting in inflammation and disease propagation. Although early research tended to focus solely on exosomal removal of unwanted cellular contents, more recent reports indicate that these nano-vesicles play an active role in intercellular signaling. Not only is the exosomal cargo cell type-specific, but it also differs between healthy and dying cells. Moreover, following exosome uptake by naïve cells, the contents from these vesicles can alter the fate of recipient cells. Since exosomes can traverse long distances, they can influence distantly located cells and tissues. This review briefly explores the role played by environmental toxins in stimulating exosome release in the context of progressive neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's, as well as certain cancers such as lung, liver, ovarian, and tracheal carcinomas.

Lung adenocarcinoma cell-derived exosomal miR-21 facilitates osteoclastogenesis

Osteoclastogenesis is the rate-limiting step in tumor osteolytic metastasis. MicroRNAs play crucial roles in tumor progression and osteoclastogenesis regulation. Recent studies have demonstrated that exosomes are able to function as messengers that deliver microRNAs between cells. However, the effects of lung adenocarcinoma cell-derived exosomal miRNAs in osteoclastogenesis remain poorly understood. In this study, we found that exosomes derived from A549 cells facilitate osteoclastogenesis. As miR-21 was involved in tumorigenesis and osteoclastogenesis, we further proved the existence of miR-21 in A549 cell-derived exosomes and investigated its function. MiR-21 overexpression in A549 cells led to increased levels of miR-21 in exosomes and facilitated osteoclastogenesis. Conversely, miR-21 depletion in A549 cells down-regulated miR-21 in exosomes and alleviated osteoclastogenesis. Mechanical experiments demonstrated that exosomal miR-21 exerted its promoting effects on osteoclastogenesis via targeting Pdcd4, which is a known target of miR-21 and a regulator of osteoclastogenesis. Finally, clinical data showed that higher miR-21 levels were associated with a worse overall survival in lung adenocarcinoma patients. In conclusion, we found that lung adenocarcinoma derived exosomal miR-21 may facilitate osteoclastogenesis, which suggests that it is a potential therapeutic target of bone metastasis.

Exosomal circRNA_100284 from arsenite-transformed cells, via microRNA-217 regulation of EZH2, is involved in the malignant transformation of human hepatic cells by accelerating the cell cycle and promoting cell proliferation

Intercellular communication between malignant cells and neighboring nonmalignant cells is involved in carcinogenesis. In the progression of carcinogenesis, exosomes are messengers for intercellular communication. Circular RNAs (circRNAs) are noncoding RNAs with functions that include regulation of the cell cycle and proliferation. However, the functions of exosomal circRNAs are not clear. The present research aimed to determine whether circRNAs secreted from arsenite-transformed human hepatic epithelial (L-02) cells are transferred into normal L-02 cells and become functionally active in the normal cells. The results showed that circRNA_100284 is involved in the malignant transformation of L-02 cells induced by arsenite. The medium from transformed L-02 cells induced upregulation of circRNA_100284, accelerated the cell cycle, and promoted proliferation of normal L-02 cells. Transformed cells transferred circRNA_100284 into normal L-02 cells via exosomes and led to the malignant transformation of the non-transformed cells. Knockdown of circRNA_100284, which reduced circRNA_100284 levels in exosomes derived from transformed L-02 cells, blocked the accelerated cell cycle and reduced proliferation and malignancy. In addition, in normal L-02 cells, exosomal circRNA_100284 derived from arsenite-transformed L-02 cells induced acceleration of the cell cycle and promoted proliferation via acting as a sponge of microRNA-217. Further, exosomal circRNA_100284 was upregulated in the sera of people exposed to arsenite. Thus, exosomes derived from transformed L-02 cells transferred circRNA_100284 to surrounding cells, which induced an accelerated cell cycle and promoted proliferation of normal liver cells and led to the malignant transformation of the non-transformed cells. The findings support the concept that exosomal circRNAs are involved in cell–cell communication during carcinogenesis induced by arsenite.

Enhanced Cardioprotection by Human Endometrium Mesenchymal Stem Cells Driven by Exosomal MicroRNA-21

Our group recently reported positive therapeutic benefit of human endometrium-derived mesenchymal stem cells (EnMSCs) delivered to infarcted rat myocardium, an effect that correlated with enhanced secretion of protective cytokines and growth factors compared with parallel cultures of human bone marrow MSCs (BMMSCs). To define more precisely the molecular mechanisms of EnMSC therapy, in the present study, we assessed in parallel the paracrine and therapeutic properties of MSCs derived from endometrium, bone marrow, and adipose tissues in a rat model of myocardial infarction (MI). EnMSCs, BMMSCs, and adipose-derived MSCs (AdMSCs) were characterized by fluorescence-activated cell sorting (FACS). Paracrine and cytoprotective actions were assessed in vitro by coculture with neonatal cardiomyocytes and human umbilical vein endothelial cells. A rat MI model was used to compare cell therapy by intramyocardial injection of BMMSCs, AdMSCs, and EnMSCs. We found that EnMSCs conferred superior cardioprotection relative to BMMSCs or AdMSCs and supported enhanced microvessel density. Inhibitor studies indicated that the enhanced paracrine actions of EnMSCs were mediated by secreted exosomes. Analyses of exosomal microRNAs (miRs) by miR array and quantitative polymerase chain reaction revealed that miR-21 expression was selectively enhanced in exosomes derived from EnMSCs. Selective antagonism of miR-21 by anti-miR treatment abolished the antiapoptotic and angiogenic effects of EnMSCs with parallel effects on phosphatase and tensin homolog (PTEN), a miR-21 target and downstream Akt. The results of the present study confirm the superior cardioprotection by EnMSCs relative to BMMSCs or AdMSCs and implicates miR-21 as a potential mediator of EnMSC therapy by enhancing cell survival through the PTEN/Akt pathway. The endometrium might be a preferential source of MSCs for cardiovascular cell therapy. Stem Cells Translational Medicine 2017;6:209-222.

The role of microRNAs in metal carcinogen-induced cell malignant transformation and tumorigenesis

MicroRNAs (miRNAs), an important component of epigenetic mechanisms of carcinogenesis, have been shown to play crucial roles in cancer initiation, metastasis, prognosis and responses to drug treatment and may serve as biomarkers for early diagnosis of cancer and tools for cancer therapy. Metal carcinogens, such as arsenic, cadmium, hexavalent chromium and nickel, are well-established human carcinogens causing various cancers upon long term exposure. However, the mechanism of metal carcinogenesis has not been well understood, which limits our capability to effectively diagnose and treat human cancers resulting from chronic metal carcinogen exposure. Over recent years, the role of miRNAs in metal carcinogenesis has been actively explored and a growing body of evidence indicates the critical involvement of miRNAs in metal carcinogenesis. This review aims to discuss recent studies showing that miRNAs play important roles in metal carcinogen-induced cell malignant transformation and tumorigenesis. Some thoughts for future further studies in this field are also presented.

Pancreatic cancer-derived exosomes transfer miRNAs to dendritic cells and inhibit RFXAP expression via miR-212-3p

It has been reported tumor-derived exosomes can transfer miRNAs to recipient cells in the tumor microenvironment, promoting tumor invasion and metastasis. The present research aimed to explore how pancreatic cancer (PC) derived exosomal miRNAs inhibited mRNA expression of dendritic cells and induced immune tolerance. Our study revealed that 9 PC-related miRNAs were increased and 208 mRNAs were inhibited in exosome-stimulated dendritic cells (exo-iDCs) compared to immature dendritic cells (iDCs). A target prediction between the 9 miRNAs and 208 mRNAs was performed by bioinformatics database analysis. From the target prediction, it was predicted and validated that regulatory factor X-associated protein (RFXAP), an important transcription factor for MHC II, was inhibited by miR-212-3p transferred from PC-secreted exosomes, resulting in decreased MHC II expression. Moreover, a clinical study showed a negative correlation between miR-212-3p and RFXAP in PC tissue. From these data, we concluded that PC-related miRNAs can be transferred to dendritic cells via exosome and inhibit target mRNA expression. More importantly, PC-derived exosomes inhibit RFXAP expression via miR-212-3p, which decrease MHC II expression and induce immune tolerance of dendritic cells. RFXAP deficiency has never been reported in solid tumors. The functions and mechanisms of RFXAP in tumors deserve future explorations.

Cross Talk between Cancer and Mesenchymal Stem Cells through Extracellular Vesicles Carrying Nucleic Acids

Extracellular vesicles (EVs) are considered to be a novel complex mechanism of cell communication within the tumor microenvironment. EVs may act as vehicles for transcription factors and nucleic acids inducing epigenetic changes in recipient cells. Since tumor EVs may be present in patient biological fluids, it is important to investigate their function and molecular mechanisms of action. It has been shown that tumor cells release EVs, which are capable of regulating cell apoptosis, proliferation, invasion, and epithelial-mesenchymal transition, as well as to suppress activity of immune cells, to enhance angiogenesis, and to prepare a favorable microenvironment for metastasis. On the other hand, EVs derived from stromal cells, such as mesenchymal stem cells (MSCs), may influence the phenotype of tumor cells through reciprocal cross talk greatly influenced by the transcription factors and nucleic acids they carry. In particular, non-coding RNAs (ncRNAs), including microRNAs and long ncRNAs, have recently been identified as the main candidates for the phenotypic changes induced in the recipient cells by EVs. ncRNAs, which are important regulators of mRNA and protein expression, can function either as tumor suppressors or as oncogenes, depending on their targets. Herein, we have attempted to revise actual evidence reported in the literature on the role of EVs in tumor biology with particular regard to the cross talk of ncRNAs between cancer cells and MSCs.

Exosomes Derived from Hypoxic Oral Squamous Cell Carcinoma Cells Deliver miR-21 to Normoxic Cells to Elicit a Prometastatic Phenotype

Hypoxia is a common feature of solid tumors and is associated with aggressiveness and poor patient outcomes. Exosomes, initially considered to be cellular "garbage dumpsters," are now implicated in mediating interactions with the cellular environment. However, the mechanisms underlying the association between exosomes and hypoxia during cancer progression remain poorly understood. In this study, we found that exosomes derived from hypoxic oral squamous cell carcinoma (OSCC) cells increased the migration and invasion of OSCC cells in a HIF-1α and HIF-2α-dependent manner. Given that exosomes have been shown to transport miRNAs to alter cellular functions, we performed miRNA sequencing of normoxic and hypoxic OSCC-derived exosomes. Of the 108 miRNAs that were differentially expressed, miR-21 stood out as one of the most significantly upregulated miRNAs under hypoxic conditions. miR-21 depletion in hypoxic OSCC cells led to decreased miR-21 levels in exosomes and significantly reduced cell migration and invasion. Conversely, restoration of miR-21 expression in HIF-1α and HIF-2α-depleted exosomes rescued OSCC cell migration and invasion. Moreover, exosomal miR-21 markedly enhanced snail and vimentin expression, while significantly decreasing E-cadherin levels in OSCC cells, in vitro and in vivo Finally, circulating exosomal miR-21 levels were closely associated with HIF-1α/HIF-2α expression, T stage, and lymph node metastasis in patients with OSCC. In conclusion, our findings suggest that the hypoxic microenvironment may stimulate tumor cells to generate miR-21-rich exosomes that are delivered to normoxic cells to promote prometastatic behaviors and prompt further investigation into the therapeutic value of exosome inhibition for cancer treatment. Cancer Res; 76(7); 1770-80. ©2016 AACR.

Exosomes derived from endometriotic stromal cells have enhanced angiogenic effects in vitro

Our objective has been to establish a pro-angiogenic role for exosomes in endometriosis and to determine whether a differential expression profile of cellular and exosomal microRNAs (miRNAs) exists in endometriosis. We performed an in vitro study of human primary endometrial stromal cells (ESCs) and human umbilical vein endothelial cells (HUVECs). We isolated and characterized exosomes from ESCs from five endometriosis patients and five phase-matched controls. Exosomes were characterized by transmission electron microscopy and NanoSight technology. MiRNA was assessed by deep sequencing and reverse transcription with quantitative polymerase chain reaction. Exosome uptake studies were achieved by means of confocal microscopy. The pro-angiogenic experiments were executed by treating HUVECs with ESC-derived exosomes. We observed differential profiles of exosomal miRNA expression between exosomes derived from endometriosis lesion cells and diseased eutopic stromal cells compared with exosomes derived from control ESCs. We also demonstrated autocrine cellular uptake of exosomes and paracrine functional angiogenic effects of exosomes on HUVECs. The results of this study support the hypothesis that exosomes derived from ESCs play autocrine/paracrine roles in the development of endometriosis, potentially modulating angiogenesis. The broader clinical implications are that Sampson’s theory of retrograde menstruation possibly encompasses the finding that exosomes work as intercellular communication modulators in endometriosis.

MiR-21: an environmental driver of malignant melanoma?

Since the mid-1950’s, melanoma incidence has been rising steadily in industrialized Caucasian populations, thereby pointing to the pivotal involvement of environmental factors in melanomagenesis. Recent evidence underlines the crucial role of microRNA (miR) signaling in cancer initiation and progression. Increased miR-21 expression has been observed during the transition from a benign melanocytic lesion to malignant melanoma, exhibiting highest expression of miR-21. Notably, common BRAF and NRAS mutations in cutaneous melanoma are associated with increased miR-21 expression. MiR-21 is an oncomiR that affects critical target genes of malignant melanoma, resulting in sustained proliferation (PTEN, PI3K, Sprouty, PDCD4, FOXO1, TIPE2, p53, cyclin D1), evasion from apoptosis (FOXO1, FBXO11, APAF1, TIMP3, TIPE2), genetic instability (MSH2, FBXO11, hTERT), increased oxidative stress (FOXO1), angiogenesis (PTEN, HIF1α, TIMP3), invasion and metastasis (APAF1, PTEN, PDCD4, TIMP3). The purpose of this review is to provide translational evidence for major environmental and individual factors that increase the risk of melanoma, such as UV irradiation, chemical noxes, air pollution, smoking, chronic inflammation, Western nutrition, obesity, sedentary lifestyle and higher age, which are associated with increased miR-21 signaling. Exosomal miR-21 induced by extrinsic and intrinsic stimuli may be superimposed on mutation-induced miR-21 pathways of melanoma cells. Thus, oncogenic miR-21 signaling may be the converging point of intrinsic and extrinsic stimuli driving melanomagenesis. Future strategies of melanoma treatment and prevention should thus aim at reducing the burden of miR-21 signal transduction.

Extracellular vesicles: potential applications in cancer diagnosis, prognosis, and epidemiology

Both normal and diseased cells continuously shed extracellular vesicles (EVs) into extracellular space, and the EVs carry molecular signatures and effectors of both health and disease. EVs reflect dynamic changes that are occurring in cells and tissue microenvironment in health and at a different stage of a disease. EVs are capable of altering the function of the recipient cells. Trafficking and reciprocal exchange of molecular information by EVs among different organs and cell types have been shown to contribute to horizontal cellular transformation, cellular reprogramming, functional alterations, and metastasis. EV contents may include tumor suppressors, phosphoproteins, proteases, growth factors, bioactive lipids, mutant oncoproteins, oncogenic transcripts, microRNAs, and DNA sequences. Therefore, the EVs present in biofluids offer unprecedented, remote, and non-invasive access to crucial molecular information about the health status of cells, including their driver mutations, classifiers, molecular subtypes, therapeutic targets, and biomarkers of drug resistance. In addition, EVs may offer a non-invasive means to assess cancer initiation, progression, risk, survival, and treatment outcomes. The goal of this review is to highlight the current status of information on the role of EVs in cancer, and to explore the utility of EVs for cancer diagnosis, prognosis, and epidemiology.

Extracellular vesicles: potential roles in regenerative medicine

Extracellular vesicles (EV) consist of exosomes, which are released upon fusion of the multivesicular body with the cell membrane, and microvesicles, which are released directly from the cell membrane. EV can mediate cell–cell communication and are involved in many processes, including immune signaling, angiogenesis, stress response, senescence, proliferation, and cell differentiation. The vast amount of processes that EV are involved in and the versatility of manner in which they can influence the behavior of recipient cells make EV an interesting source for both therapeutic and diagnostic applications. Successes in the fields of tumor biology and immunology sparked the exploration of the potential of EV in the field of regenerative medicine. Indeed, EV are involved in restoring tissue and organ damage, and may partially explain the paracrine effects observed in stem cell-based therapeutic approaches. The function and content of EV may also harbor information that can be used in tissue engineering, in which paracrine signaling is employed to modulate cell recruitment, differentiation, and proliferation. In this review, we discuss the function and role of EV in regenerative medicine and elaborate on potential applications in tissue engineering.