Exosome-shuttling microRNA-21 promotes cell migration and invasion-targeting PDCD4 in esophageal cancer

Tiny Actors in the Big Cellular World: Extracellular Vesicles Playing Critical Roles in Cancer

Communications among cells can be achieved either via direct interactions or via secretion of soluble factors. The emergence of extracellular vesicles (EVs) as entities that play key roles in cell-to-cell communication offer opportunities in exploring their features for use in therapeutics; i.e., management and treatment of various pathologies, such as those used for cancer. The potential use of EVs as therapeutic agents is attributed not only for their cell membrane-bound components, but also for their cargos, mostly bioactive molecules, wherein the former regulate interactions with a recipient cell while the latter trigger cellular functions/molecular mechanisms of a recipient cell. In this article, we highlight the involvement of EVs in hallmarks of a cancer cell, particularly focusing on those molecular processes that are influenced by EV cargos. Moreover, we explored the roles of RNA species and proteins carried by EVs in eliciting drug resistance phenotypes. Interestingly, engineered EVs have been investigated and proposed as therapeutic agents in various in vivo and in vitro studies, as well as in several clinical trials.

Uncovering the Exosomes Diversity: A Window of Opportunity for Tumor Progression Monitoring

Cells can communicate through special “messages in the bottle”, which are recorded in the bloodstream inside vesicles, namely exosomes. The exosomes are nanovesicles of 30–100 nm in diameter that carry functionally active biological material, such as proteins, messanger RNA (mRNAs), and micro RNA (miRNAs). Therefore, they are able to transfer specific signals from a parental cell of origin to the surrounding cells in the microenvironment and to distant organs through the circulatory and lymphatic stream. More and more interest is rising for the pathological role of exosomes produced by cancer cells and for their potential use in tumor monitoring and patient follow up. In particular, the exosomes could be an appropriate index of proliferation and cancer cell communication for monitoring the minimal residual disease, which cannot be easily detectable by common diagnostic and monitoring techniques. The lack of unequivocal markers for tumor-derived exosomes calls for new strategies for exosomes profile characterization aimed at the adoption of exosomes as an official tumor biomarker for tumor progression monitoring.

Esophageal Microenvironment: From Precursor Microenvironment to Premetastatic Niche

Esophageal cancer (EC) is the sixth most deadly cancer, and its incidence is still increasing year by year. Although the researches on the molecular mechanisms of EC have been widely carried out and incremental progress has been made, its overall survival rate is still low. There is cumulative evidence showing that the esophageal microenvironment plays a vital role in the development of EC. In precancerous lesions of the esophagus, high-risk environmental factors can promote the development of precancerous lesions by inducing the production of inflammatory factors and the recruitment of immune cells. In the tumor microenvironment, tumor-promoting cells can inhibit anti-tumor immunity and promote tumor progression through a variety of pathways, such as bone marrow-derived suppressor cells (MDSCs), tumor-associated fibroblasts (CAFs), and regulatory T cells (Tregs). The formation of extracellular hypoxia and acidic microenvironment and the change of extracellular matrix stiffness are also important factors affecting tumor progression and metastasis. Simultaneously, primary tumor-derived cytokines and bone marrow-derived immune cells can also promote the formation of pre-metastasis niche of EC lymph nodes, which are beneficial to EC lymph node metastasis. Further research on the specific mechanism of these processes in the occurrence, development, and metastasis of each EC subtype will support us to grasp the overall pre-cancerous prevention, targeted treatment, and metastatic assessment of EC.

Deep Sequencing of Small RNAs from Neurosurgical Extracellular Vesicles Substantiates miR-486-3p as a Circulating Biomarker that Distinguishes Glioblastoma from Lower-Grade Astrocytoma Patients

Extracellular vesicles (EVs) play key roles in glioblastoma (GBM; astrocytoma grade IV) biology and are novel sources of biomarkers. EVs released from GBM tumors can cross the blood-brain-barrier into the periphery carrying GBM molecules, including small non-coding RNA (sncRNA). Biomarkers cargoed in circulating EVs have shown great promise for assessing the molecular state of brain tumors in situ. Neurosurgical aspirate fluids captured during tumor resections are a rich source of GBM-EVs isolated directly from tumor microenvironments. Using density gradient ultracentrifugation, EVs were purified from cavitron ultrasonic surgical aspirate (CUSA) washings from GBM (n = 12) and astrocytoma II-III (GII-III, n = 5) surgeries. The sncRNA contents of surgically captured EVs were profiled using the Illumina^® NextSeq^TM 500 NGS System. Differential expression analysis identified 27 miRNA and 10 piRNA species in GBM relative to GII-III CUSA-EVs. Resolved CUSA-EV sncRNAs could discriminate serum-EV sncRNA profiles from GBM and GII-III patients and healthy controls and 14 miRNAs (including miR-486-3p and miR-106b-3p) and cancer-associated piRNAs (piR_016658, _016659, _020829 and _204090) were also significantly expressed in serum-EVs. Circulating EV markers that correlate with histological, neuroradiographic and clinical parameters will provide objective measures of tumor activity and improve the accuracy of GBM tumor surveillance.

Effects of miR-135a-5p and miR-141 on proliferation, invasion and apoptosis of colorectal cancer SW620 cells

Effects of miR-135a-5p and miR-141 on the biological function of colorectal cancer SW620 cells were investigated. Fifty-four specimens of cancer tissues and 54 specimens of corresponding adjacent tissues in colon cancer patients who were treated in The Central Hospital of Wuhan from March 2014 to March 2015 were collected. RT-PCR was used to detect the expression levels of miR-135a-5p and miR-141 in cancer tissues and adjacent tissues. The miR-135a-5p inhibitor and miR-141 mimic carriers were established. The cell proliferation was detected by CCK8, the invasion ability of cells in vitro was evaluated by Transwell chamber, and cell apoptosis of each group was detected by flow cytometry. The results of RT-qPCR showed that expression levels of miR-135a-5p in colorectal cancer tissues were significantly higher than those in adjacent tissues, the expression levels of miR-141 in colorectal cancer tissues were significantly lower than those in adjacent tissues, and the difference was statistically significant (P<0.001). The cell survival rates of the miR-135a-5p inhibitor group and the miR-141 mimic group were significantly lower than those of the NC group and the blank group 48 and 72 h after transfection (P<0.001). The number of invasive cells in the miR-135a-5p inhibitor group and the miR-141 mimic group was significantly lower than that in the blank group and the NC group (P<0.001). Apoptosis rate was significantly higher than that of the NC group and the blank group (P<0.001). In conclusion, low expression levels of miR-135a-5p and miR-141 in colorectal adenomas suggested that miR-135a-5p and miR-141 could act as tumor suppressors in the development of colorectal adenomas; miR-135a-5p and miR-141 inhibited the proliferation and invasion of colon cancer SW620 cells and promoted apoptosis of colon cancer cells.

Clinical relevance and functional significance of cell-free microRNA-1260b expression profiles in infiltrative myxofibrosarcoma

Infiltrative tumor growth into adjacent soft tissues is a major cause of the frequent recurrence and tumor-related death of myxofibrosarcoma (MFS), but no useful biomarkers reflecting tumor burden and infiltrative growth are available. While emerging evidence suggests a diagnostic and functional role of extracellular/circulating microRNA (miRNA) in various malignant diseases, their significance in MFS patients remains unknown. Global miRNA profiling identified four upregulated miRNAs in MFS patient sera and culture media of MFS cells. Among these, serum miR-1260b level was significantly upregulated in patient serum discriminating from healthy individuals and closely correlated with clinical status and tumor dynamics in MFS-bearing mice. In addition, high miR-1260b expression in serum was correlated with radiological tail-like patterns, characteristic of the infiltrative MFS. The extracellular miR-1260b was embedded in tumor-derived extracellular vesicles (EVs) and promoted cellular invasion of MFS through the downregulation of PCDH9 in the adjacent normal fibroblasts. Collectively, circulating miR-1260b expression may represent a novel diagnostic target for tumor monitoring of this highly aggressive sarcoma. Moreover, EV-miR-1260b could act as a transfer messenger to adjacent cells and mediate the infiltrative growth of MFS, providing new insights into the mechanism of infiltrative nature via crosstalk between tumor cells and their microenvironment.

Role of exosomal miR‑21 in the tumor microenvironment and osteosarcoma tumorigenesis and progression (Review)

Osteosarcoma is the most common bone tumor affecting both adolescents and children. Early detection is critical for the effective treatment of the disease. Derived from cancer cells, miR‑21 contained within exosomes in the tumor microenvironment may act on both cancer cells and the surrounding tumor microenvironment (TME), including immune cells, endothelial cells and fibroblasts. In human serum and plasm, the level of exosomal miR‑21 between osteosarcoma patients and healthy controls differs, supporting the role of miR‑21 as a biomarker for osteosarcoma. The involvement of a number of miR‑21 target genes in tumor progression suggests that miR‑21 may significantly affect the plasticity of cancer cells, leading to tumor progression, metastasis, angiogenesis and immune escape in osteosarcoma. Understanding the biogenesis and functions of exosomal miR‑21 is of great value for the diagnosis and therapy of cancer, including osteosarcoma. The present review discusses the role of miR‑21 in the tumor microenvironment, and in the development and progression of osteosarcoma, with an aim to summarize the functions of this miRNA in cancer.

Exosomes with low miR-34c-3p expression promote invasion and migration of non-small cell lung cancer by upregulating integrin α2β1

Exosomes play critical roles in regulating various physiological and pathological processes, including immune stimulation, immune suppression, cardiovascular diseases, and cancers. Recent studies show that exosomes that transport specific microRNAs (miRNAs) are involved in tumor development. However, the molecular mechanism by which tumor invasion and migration are regulated by exosomes from non-small cell lung cancer (NSCLC) is not well understood. Here, we show that exosomes shuttling low levels of miR-34c-3p are involved in NSCLC progression. Our results showed that exosomes derived from NSCLC cells carrying low levels of miR-34c-3p could be transported into the cytoplasm of NSCLC cells and accelerate NSCLC invasion and migration by upregulating integrin α2β1. A luciferase assay revealed that integrin α2β1 was the direct target of miR-34c-3p, and overexpression of integrin α2β1 could promote the invasion and migration of NSCLC cells. The analysis of exosomes derived from clinical serum samples indicated that the expression of miR-34c-3p was significantly downregulated in exosomes from NSCLC patients compared with that of normal controls. A549-derived exosomes promoted NSCLC cells lung metastases in vivo. Exosomes shuttling low levels of miR-34c-3p were associated with the progression of NSCLC in vitro and in vivo. Our data demonstrate that exosomes shuttling low levels of miR-34c-3p can accelerate the invasion and migration of NSCLC by upregulating integrin α2β1. MiR-34c-3p can be a diagnostic and prognostic marker for NSCLC. High expression of integrin α2β1 is positively related to the migration and metastasis of NSCLC cells.

MicroRNA-301b and its target gene synaptosome-associated protein 91 as important modulators in esophageal cancer: functional experiments

The aim of this study was to probe the influence of microRNA-301b (miR-301b) in esophageal cancer pathogenesis. Based on the data acquired from The Cancer Genome Atlas database, we found that miR-301b was highly expressed in esophageal cancer tissues and high expression of miR-301b was related to worse prognosis in patients with esophageal cancer. Quantitative real-time PCR revealed that the expression of miR-301b was higher in all examined esophageal cancer cell lines (ECA109, KY-SE150, TE-1, and NEC) than that in a human esophageal epithelial cell line (HEEC). Upregulation/downregulation of miR-301b facilitated/suppressed the growth, migration, and invasion of ECA109/KY-SE150 cells. Synaptosome-associated protein 91 (SNAP91) was proved to be one of the target genes of miR-301b and was negatively modulated by miR-301b. Besides, SNAP91 was lowly expressed in human esophageal cancer tissues and cell lines. Meanwhile, low expression of SNAP91 was concerned with poor prognosis in patients with esophageal cancer. Furthermore, we discovered that overexpression/depletion of SNAP91 suppressed/facilitated the proliferation of KY-SE150/ECA109 cells. MiR-301b and SNAP91 had little impact on HEEC cell proliferation and this degree of influence was negligible compared with their impacts on esophageal cancer cell proliferation. By rescue assay, we showed that overexpression of SNAP91 restrained the growth, migration, and invasion of ECA109 cells with overexpressed miR-301b while knockdown of SNAP91 showed the contrary effects on KY-SE150 cells with downregulated miR-301b. These consequences indicated that miR-301b played an important effect on esophageal cancer cells through regulating SNAP91, insinuating that miR-301b/SNAP91 might be novel potential targets for esophageal cancer therapy and prognosis.

Exosomes-microRNAs interacted with gastric cancer and its microenvironment: a mini literature review

Exosomes have appeared as fundamental vehicle-modulated crosstalk among various cells in the tumor microenvironment. The systematic understanding of exosomes in gastric cancer (GC) enhances our comprehension about the tumor growth, metastasis, chemoresistance and diagnosis of cancers. The versatile functions of exosomes provide reasonable explanations about the propensity for GC metastasis. The selectively enriched components, especially some exosomal miRNAs, are potential noninvasive biomarkers for sensitive and specific GC diagnosis. Given the characteristics of exosomes, frontier researchers are stimulated to modulate the biogenesis, concentrations or release of exosomes so as to disturb malignant signals between cells. Abnormal expression profiles of exosomal miRNAs afford potential GC therapeutic or diagnostic strategies in future.

Upregulation of exosomal microRNA‑21 in pancreatic stellate cells promotes pancreatic cancer cell migration and enhances Ras/ERK pathway activity

Pancreatic stellate cells (PSCs) are typically activated in pancreatic ductal adenocarcinoma (PDAC) and release exosomes containing high levels of microRNA‑21 (miR‑21). However, the specific roles of exosomal miR‑21 in regulating the PDAC malignant phenotype remain unknown. The present study aimed to determine the effects of exosomal miR‑21 on the migratory ability of PDAC cells and explore the potential underlying molecular mechanism. Weighted gene correlation network and The Cancer Genome Atlas database analysis revealed that high miR‑21 levels were associated with a poor prognosis in patients with pancreatic adenocarcinoma, and that the Ras/ERK signaling pathway may be a potential target of miR‑21. In vitro, PDAC cells were demonstrated to internalize the PSC-derived exosome, resulting in high miR‑21 levels, which subsequently promoted cell migration, induced epithelial‑to‑mesenchymal transition (EMT) and increased matrix metalloproteinase‑2/9 activity. In addition, exosomal miR‑21 increased the levels of ERK1/2 and Akt phosphorylation in PDAC cells. Collectively, these results suggested that PSC‑derived exosomal miR‑21 may promote PDAC cell migration and EMT and enhance Ras/ERK signaling activity. Thus, miR‑21 may be a potential cause of poor prognosis in patients with pancreatic cancer and a new treatment target.

Cancer-Derived Exosomes: Their Role in Cancer Biology and Biomarker Development

Exosomes are a subset of tiny extracellular vesicles manufactured by all cells and are present in all body fluids. They are produced actively in tumor cells, which are released and utilized to facilitate tumor growth. Their characteristics enable them to assist major cancer hallmarks, leveraged by cancer cells in fostering cancer growth and spread while implementing ways to escape elimination from the host environment. This review updates on the latest progress on the roles of cancer-derived exosomes, of 30-100 nm in size, in deregulating paracrine trafficking in the tumor microenvironment and circulation. Thus, exosomes are being exploited in diagnostic biomarker development, with its potential in clinical applications as therapeutic targets utilized in exosome-based nanoparticle drug delivery strategies for cancer therapy. Ongoing studies were retrieved from PubMed^® and Scopus database and ClinicalTrials.gov registry for review, highlighting how cancer cells from entirely different cell lines rely on genetic information carried by their exosomes for homotypic and heterotypic intercellular communications in the microenvironment to favor proliferation and invasion, while establishing a pre-metastatic niche in welcoming cancer cells' arrival. We will elaborate on the trafficking of tumor-derived exosomes in fostering cancer proliferation, invasion, and metastasis in hematopoietic (leukemia and myeloma), epithelial (breast cancer), and mesenchymal (soft tissue sarcoma and osteosarcoma) cancers. Cancer-derived exosomal trafficking is observed in several types of liquid or solid tumors, confirming their role as cancer hallmark enabler. Their enriched genetic signals arising from their characteristic DNA, RNA, microRNA, and lncRNA, along with specific gene expression profiles, protein, or lipid composition carried by the exosomal cargo shed into blood, saliva, urine, ascites, and cervicovaginal lavage, are being studied as a diagnostic, prognostic, or predictive cancer biomarker. We reveal the latest research efforts in exploiting the use of nanoparticles to improve the overall cancer diagnostic capability in the clinic.

Novel Epigenetic Biomarkers in Pregnancy-Related Disorders and Cancers

As the majority of cancers and gestational diseases are prognostically stage- and grade-dependent, the ultimate goal of ongoing studies in precision medicine is to provide early and timely diagnosis of such disorders. These studies have enabled the development of various new diagnostic biomarkers, such as free circulating nucleic acids, and detection of their epigenetic changes. Recently, extracellular vesicles including exosomes, microvesicles, oncosomes, and apoptotic bodies have been recognized as powerful diagnostic tools. Extracellular vesicles carry specific proteins, lipids, DNAs, mRNAs, and miRNAs of the cells that produced them, thus reflecting the function of these cells. It is believed that exosomes, in particular, may be the optimal biomarkers of pathological pregnancies and cancers, especially those that are frequently diagnosed at an advanced stage, such as ovarian cancer. In the present review, we survey and critically appraise novel epigenetic biomarkers related to free circulating nucleic acids and extracellular vesicles, focusing especially on their status in trophoblasts (pregnancy) and neoplastic cells (cancers).

Exosomal miR-21 regulates the TETs/PTENp1/PTEN pathway to promote hepatocellular carcinoma growth

Background

As an important means of communication, exosomes play an important role in the development of hepatocellular carcinoma (HCC).

Methods

Bioinformatics analysis, dual-luciferase reporter assays, methylation-specific quantitative PCR, and ChIP-PCR analysis were used to gain insight into the underlying mechanism of miR-21 in HCC.

Results

The detection of miRNAs in exosomes of HCC showed that miR-21 expression in exosomes was positively correlated with the expression level of miR-21 in cells and negatively correlated with the expression of its target genes PTEN, PTENp1 and TETs. HCC cell-derived exosomes could increase miR-21 and p-Akt expression in HCC cells and downregulate the expression of PTEN, PTENp1 and TETs. MiR-21 inhibitors or PTENp1 overexpression vectors could weaken the effect of the abovementioned exosomes and simultaneously weaken their role in promoting cell proliferation and migration and inhibiting apoptosis. Further studies showed that miR-21 not only directly regulated the expression of PTEN, PTENp1 and TETs but also increased the methylation level of the PTENp1 promoter by regulating the expression of TETs, thereby inhibiting the expression of PTENp1 and further downregulating the expression of PTEN.

Conclusions

Exosomal miR-21 can regulate the expression of the tumor suppressor genes PTEN and PTENp1 in various ways and affect the growth of HCC cells.

Circulating exosomal miRNAs: clinical significance in human cancers

Introduction: The identification of novel noninvasive biomarkers to ameliorate early-diagnosis, and disease prognosis, as well as to support personalized treatment and monitoring decisions is of first clinical priority for cancer patients' care. Exosomes are natural endosome-derived extracellular vesicles that have emerged as crucial mediators of intercellular communication and tumor progression. Considering that deregulated miRNA levels have been described in numerous human malignancies and that tumor-derived exosomes reflect miRNA expression of donor tumor cells, the evaluation of exosome-derived circulating miRNAs (exomiRs) may offer a new promising class of noninvasive molecular markers to improve patients' management and quality-of-life. Areas covered: In the current review we have summarized the existing knowledge on the clinical relevance of circulating exosomal miRNAs in improving cancer diagnosis and prognosis, and thus supporting personalized patients' management Expert commentary: Cancer research has highlighted the abundance of exomiRs in patients' plasma and serum samples, as well as their biomarker capabilities in the vast majority of human malignancies studied so far. Their analytical stability constitutes exomiRs ideal molecular markers to overcome numerous limitations of cancer clinical management, while future large-scale studies should unveil exomiRs translational utility in modern cancer molecular diagnostics.

Hypoxic exosomes facilitate angiogenesis and metastasis in esophageal squamous cell carcinoma through altering the phenotype and transcriptome of endothelial cells

Background

In cancer progression, hypoxia, or low oxygen tension, is a major regulator of tumor aggressiveness and metastasis. However, how cancer cells adapt to the hypoxia and communicate with other mesenchymal cells in microenvironment during tumor development remains to be elucidated. Here, we investigated the involvement of exosomes in modulating angiogenesis and enhancing metastasis in esophageal squamous cell carcinoma (ESCC).

Methods

Differential centrifugation, transmission electron microscopy and nanoparticle tracking analysis were used to isolate and characterize exosomes. Colony formation and transwell assay were performed to assess the proliferation, migration and invasion of human umbilical vein endothelial cells (HUVECs). The tube formation assay and matrigel plug assay were used to evaluate the vascular formation ability of HUVECs in vitro and in vivo respectively. An in vivo nude mice model was established to detect the regulatory role of exosomes in ESCC progression. Microarray analysis was performed to analyze the transcriptome profiles in HUVECs.

Results

Exosomes derived from ESCC cells cultured under hypoxia played a better role in promoting proliferation, migration, invasion and tube formation of HUVECs in vitro and in vivo than exosomes from ESCC cells cultured under normoxia. Moreover, hypoxic exosomes significantly enhanced the tumor growth and lung metastasis compared with normoxic exosomes in nude mice models. Interestingly, endothelial cells were programmed by hypoxic and normoxic exosomes from ESCC cells which altered the transcriptome profile of HUVECs.

Conclusions

Taken together, our data identified an angiogenic role of exosomes from ESCC cells which shed light on the further application of exosomes as valuable therapeutic target for ESCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1384-8) contains supplementary material, which is available to authorized users.

Intercellular Crosstalk Via Extracellular Vesicles in Tumor Milieu as Emerging Therapies for Cancer Progression

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Increasing evidence has suggested that extracellular vesicles (EV) mediated bidirectional transfer of functional molecules (such as proteins, different types of RNA, and lipids) between cancer cells and tumor stromal cells (immune cells, endothelial cells, fibroblasts, stem cells) and strongly contributed to the reinforcement of cancer progression. Thus, intercellular EV-mediated signaling in tumor microenvironment (TME) is essential in the modulation of all processes that support and promote tumor development like immune suppression, angiogenesis, invasion and metastasis, and resistance of tumor cells to anticancer treatments.

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Besides EV potential to revolutionize our understanding of the cancer cell-stromal cells crosstalk in TME, their ability to selectively transfer different cargos to recipient cells has created excitement in the field of tumortargeted delivery of specific molecules for anticancer treatments. Therefore, in tight connection with previous findings, this review brought insight into the dual role of EV in modulation of TME. Thus, on one side EV create a favorable phenotype of tumor stromal cells for tumor progression; however, as a future new class of anticancer drug delivery systems EV could re-educate the TME to overcome main supportive processes for malignancy progression.

Effect of immunosuppression in miRNAs from extracellular vesicles of colorectal cancer and their influence on the pre-metastatic niche

Colorectal cancer (CRC) occurs with more aggressiveness in kidney transplant recipients compared to the general population. Immunosuppressive therapy plays a crucial role in the development of post-transplant malignancy. Concretely, cyclosporine A (CsA) has intrinsic pro-oncologic properties, while several studies report a regression of cancer after the introduction of rapamycin (RAPA). However, their effect on the extracellular vesicle (EV) content from CRC cell lines and their relevance in the pre-metastatic niche have not yet been studied. Here, we investigated the effect of RAPA and CsA in EV-miRNAs from metastatic and non-metastatic CRC cell lines and the role of relevant miRNAs transferred into a pre-metastatic niche model. EV-miRNA profiles showed a significant upregulation of miR-6127, miR-6746-5p, and miR-6787-5p under RAPA treatment compared to CsA and untreated conditions in metastatic cell lines that were not observed in non-metastatic cells. From gene expression analysis of transfected lung fibroblasts, we identified 22 shared downregulated genes mostly represented by the histone family involved in chromatin organization, DNA packaging, and cell cycle. These results suggest that EV-miR-6127, miR-6746-5p and miR-6787-5p could be a potential epigenetic mechanism induced by RAPA therapy in the regulation of the pre-metastatic niche of post-transplant colorectal cancer.

Tumor-derived extracellular vesicles: reliable tools for Cancer diagnosis and clinical applications

BACKGROUND

Studies have recently revealed that almost every type of cells including tumor cells abundantly release small vesicles known as extracellular vesicles (EVs) into the extracellular milieu. EVs carry a repertoire of biological molecules including nucleic acids, proteins, lipids, and carbohydrates and transport their cargo between cells in the vicinity as well as distantly located cells and hence act as messengers of intercellular communication. In this review, we aimed to discuss the tumor-derived exosome biology and the pivotal roles of exosomes in cancer diagnosis and treatment.

METHODS

In the present review study, the authors studied several articles over the past two decades published on the kinetics of EVs in tumor environment as well as on the application of these vesicles in cancer diagnosis and therapy.

RESULTS

A growing body of evidence indicates that nucleic acids such as microRNAs (miRNAs) transferring by EVs participate to create a conducive tumor environment. As EV-associated miRNAs are tissue-specific and present in most biological fluids, they hold great potential for clinical application in cancer early diagnosis, prognosis, and treatment response. Furthermore, exosomes can serve as drug delivery vehicles transferring miRNAs as well as therapeutic agents to target cells. These nano-vesicles exhibit ideal properties in comparison with the synthetic carriers that attracted scientist's attention in the field of nanotechnology medicine. Scientists have employed different strategies to build exosomes-based drug delivery system. In general, two methods (direct engineering and indirect engineering) are being utilized to produce artificial exosomes. Para-clinical data have confirmed the beneficial effects of engineering exosomes in cancer therapy.

CONCLUSION

Exosomal miRNAs hold great promise for clinical application in early diagnosis and treatment of cancers. In addition, in spite of enthusiastic results obtained by engineered exosomes, however, there is an increasing concern over the use of optimal methods for engineering exosomes and the safety of engineered exosomes in clinical trials is still unclear.

Total internal reflection-based single-vesicle in situ quantitative and stoichiometric analysis of tumor-derived exosomal microRNAs for diagnosis and treatment monitoring

Purpose: Exosomes (EXs) have been increasingly recognized as natural nanoscale vehicles for microRNA (miRNA)-based cell-cell communication and an ideal source of miRNA biomarkers in bodily fluids. Current methods allow bulk analysis of the miRNA contents of EXs, but these approaches are not suitable for the in situ stoichiometry of exosomal miRNAs and fail to reveal phenotypic heterogeneity at the single-vesicle level. This study aimed to develop a single vesicle-based, mild, precise, but versatile method for the in situ quantitative and stoichiometric analysis of exosomal miRNAs.

Methods: A total internal reflection fluorescence (TIRF)-based single-vesicle imaging assay was developed for direct visualization and quantification of the single-vesicles of EXs and their miRNA contents in serum microsamples. The assay uses co-delivery of inactive split DNAzymes and fluorescence-quenched substrates into nanosized EXs treated with streptolysin O to produce a target miRNA-activated catalytic cleavage reaction that amplifies the readout of fluorescence signal. We perform the in situ quantitative and stoichiometric analysis of serum exosomal hsa-miRNA-21 (miR-21), a common cancer biomarker, by using the developed TIRF imaging assay.

Results: The TIRF imaging assay for serum exosomal miR-21 can distinguish cancer patients from healthy subjects with better performance than conventional real-time polymerase chain reaction (PCR) assay. The exosomal miR-21 level in serum is also informative for monitoring tumor progression and responses to treatment. Moreover, the TIRF assays can readily determine the precise stoichiometry of target exosomal miRNA contents in situ by delivering molecular beacon (MB) probes into EXs.

Conclusions: The created TIRF imaging platform shows high applicability to serve as a universal and useful tool for the single-vesicle in situ quantitative and stoichiometric analysis of other disease-associated exosomal miRNAs markers and provide valuable insight into the physiological relevance of EX-mediated miRNA communication.

Exosomal transfer of miR-501 confers doxorubicin resistance and tumorigenesis via targeting of BLID in gastric cancer

Exosomal transfer of oncogenic miRNAs can enhance recipient cell growth, metastasis and chemoresistance. Currently we found that microRNA-501-5p (miR-501) was overexpressed in doxorubicin-resistant gastric cancer (GC) SGC7901/ADR cell-secreted exosomes (ADR Exo) than that in SGC7901 cell-secreted exosomes (7901 Exo). ADR Exo was internalized by SGC7901, and a Cy3-miR-501 mimic was transferred from SGC7901/ADR to SGC7901 via exosomes. ADR Exo conferred doxorubicin resistance, proliferation, migration and invasion abilities to negative control miRNA inhibitor-expressing GC cells, whereas it inhibited apoptosis. MiR-501 knockdown or BH3-like motif-containing protein, cell death inducer (BLID) overexpression could reverse the effects of ADR Exo on recipient cells. SGC7901 cells cocultured with SGC7901/ADR prior to treatment with GW4869 or transfection of a miR-501 inhibitor were sensitive to doxorubicin and exhibited attenuated proliferation, migration and invasion and increased apoptosis. The intratumoral injection of ADR Exo into negative control miRNA inhibitor-expressing SGC7901 cells induced rapid subcutaneous tumor growth and resistance to doxorubicin compared to that of miR-501 knockdown or BLID-overexpressing cells. This effect is possibly achieved by exosomal miR-501-induced downregulation of BLID, subsequent inactivation of caspase-9/-3 and phosphorylation of Akt. Exosomal miR-501 might be a therapeutic target for GC.

The research advances of exosomes in esophageal cancer

Esophageal carcinoma (EC) is one of the most common human digestive tract tumors, with high morbidity and mortality. It is necessary to elucidate the mechanism of cancer progression and seek early EC diagnostic markers for prompt detection and intervention. Exosomes are membrane nanovesicles secreted from many nucleated cells, 30-100 nm in diameter, containing various proteins, lipids and nucleic acids. They exist in peripheral blood, urine, ascites and other body fluids, widely engaged with intercellular material exchange and signal communication. Exosomes secreted from EC cells or tissues conduct important functions in tumor growth and progression. The detection and analysis of tumor-derived or tumor-associated exosomes has potential for EC early diagnosis and prognosis assessment. In the present paper, the exosomes' biological behaviors, isolation, detection and functions in EC progression - using as potential biomarkers for EC diagnosis or prognosis - are reviewed.

Exosomes in esophageal cancer: A review on tumorigenesis, diagnosis and therapeutic potential

Exosomes are nanovesicles secreted from various types of cells and can be isolated from various bodily fluids, such as blood and urine. The number and molecular contents, including proteins and RNA of exosomes, have been shown to reflect their parental cell origins, characteristics and biological behaviors. An increasing number of studies have demonstrated that exosomes play a role in the course of tumorigenesis, diagnosis, treatment and prognosis, although its precise functions in tumors are still unclear. Moreover, owing to a lack of a standard approach, exosomes and its contents have not yet been put into clinical practice successfully. This review aims to summarize the current knowledge on exosomes and its contents in esophageal cancer as well as the current limitations/challenges in its clinical application, which may provide a basis for an all-around understanding of the implementation of exosomes and exosomal contents in the surveillance and therapy of esophageal cancer.

Exosomes as Therapeutic Vehicles for Cancer

Background

Exosomes are membrane-enclosed extracellular vesicles implicated in cell-cell communication. Exosomes contain proteins, mRNAs, non-coding RNAs (miRNAs and lncRNAs) and lipids that are derived from producing cells. These nano-sized vesicles are present in biofluids including blood, urine, saliva, amniotic fluid, semen and conditioned media of cultured cells.

Methods

This review summarizes current progress on the strategies of development of diagnostic biomarkers and drug loading onto exosomes for overcoming cancer progression.

Results

A number of studies indicate that the exosome appears to be a key player in tissue repair and regeneration of in a number of animal disease models. In addition, alterations of the molecular profiles in exosomes are known to be correlated with the disease progression including cancer, suggesting their usefulness in disease diagnosis and prognosis. Studies utilizing engineered exosomes either by chemical or biological methods have demonstrated promising results in a number of animal models with cancer.

Conclusion

Understanding the molecular and cellular properties of exosomes offer benefits for cancer diagnosis by liquid biopsy and for their application in therapeutic drug delivery systems. Studies have shown that genetic or molecular engineering of exosomes augmented their target specificity and anticancer activity with less toxicity. Thus, deeper understanding of exosome biology will facilitate their therapeutic potential as an innovative drug delivery system for cancer.

Non-canonical processes that shape the cell migration landscape

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

Extracellular Vesicles in Cancer: Purpose and Promise

Extracellular vesicles refer collectively to a heterogeneous group of membrane-bound vesicles released from cells and loaded with bioactive proteins, nucleic acids, and lipids. The concept of extracellular vesicles has rapidly evolved from once being viewed as cellular debris to their recognition as packets of cellular information with considerable promise for clinical applications as biomarker platforms and therapeutic vehicles. These shed vesicles have emerged as critical mediators of intercellular communication in both local and distant microenvironments during normal physiological processes, as well as in orchestrating systemic pathophysiological events in disease. This mode of cellular crosstalk is particularly relevant to modulating the tumor microenvironment and orchestrating paths of least resistance during metastases. Here, we describe recent advances for the roles of extracellular vesicles in tumor progression and their potential as disease biomarkers.

Exosomes of pasteurized milk: potential pathogens of Western diseases

Milk consumption is a hallmark of western diet. According to common believes, milk consumption has beneficial effects for human health. Pasteurization of cow's milk protects thermolabile vitamins and other organic compounds including bioactive and bioavailable exosomes and extracellular vesicles in the range of 40-120 nm, which are pivotal mediators of cell communication via systemic transfer of specific micro-ribonucleic acids, mRNAs and regulatory proteins such as transforming growth factor-β. There is compelling evidence that human and bovine milk exosomes play a crucial role for adequate metabolic and immunological programming of the newborn infant at the beginning of extrauterine life. Milk exosomes assist in executing an anabolic, growth-promoting and immunological program confined to the postnatal period in all mammals. However, epidemiological and translational evidence presented in this review indicates that continuous exposure of humans to exosomes of pasteurized milk may confer a substantial risk for the development of chronic diseases of civilization including obesity, type 2 diabetes mellitus, osteoporosis, common cancers (prostate, breast, liver, B-cells) as well as Parkinson's disease. Exosomes of pasteurized milk may represent new pathogens that should not reach the human food chain.

The potential role of miRNAs and exosomes in chemotherapy in ovarian cancer

Chemoresistance is one of the major obstacles in the treatment of cancer patients. It poses a fundamental challenge to the effectiveness of chemotherapy and is often linked to relapse in patients. Chemoresistant cells can be identified in different types of cancers; however, ovarian cancer has one of the highest rates of chemoresistance-related relapse (50% of patients within 5 years). Resistance in cells can either develop through prolonged cycles of treatment or through intrinsic pathways. Mechanistically, the problem of drug resistance is complex mainly because numerous factors are involved, such as overexpression of drug efflux pumps, drug inactivation, DNA repair mechanisms and alterations to and/or mutations in the drug target. Additionally, there is strong evidence that circulating miRNAs participate in the development of chemoresistance. Recently, miRNAs have been identified in exosomes, where they are encapsulated and hence protected from degradation. These miRNAs within exosomes (exo-miRNAs) can regulate the gene expression of target cells both locally and systemically. Exo-miRNAs play an important role in disease progression and can potentially facilitate chemoresistance in cancer cells. In addition, and from a diagnostic perspective, exo-miRNAs profiles may contribute to the development of predictive models to identify responder and non-responder chemotherapy. Such model may also be used for monitoring treatment response and disease progression. Exo-miRNAs may ultimately serve as both a predictive biomarker for cancer response to therapy and as a prognostic marker for the development of chemotherapy resistance. Therefore, this review examines the potential role of exo-miRNAs in chemotherapy in ovarian cancer.

Extracellular vesicle secretion of miR-142-3p from lung adenocarcinoma cells induces tumor promoting changes in the stroma through cell-cell communication

Extracellular vesicles (EVs) are mediators of communication between cancer cells and the surrounding tumor microenvironment. EV content is able to influence key tumorigenic changes including invasion, metastasis, and inducing pro-tumor changes in the stroma. MiR-142-3p is a known tumor suppressor in LAC and was recently shown to be enriched within LAC EVs, indicating its potential as a key signaling miRNA. Our research demonstrates the role EV associated miR-142-3p plays when transferred from LAC cells to both endothelial and fibroblast cells. We demonstrate that transfer of miR-142-3p in LAC EVs to endothelial cells promotes angiogenesis through inhibition of TGFβR1. Additionally, we show EV associated miR-142-3p promotes the cancer-associated fibroblast phenotype in lung fibroblast cells which we show is independent of TGFβ signaling. These findings suggest that miR-142-3p within LAC EVs can be transferred from LAC cells to both endothelial and fibroblast cells to promote tumor associated changes.

Upregulation of miR-96 promotes radioresistance in glioblastoma cells via targeting PDCD4

Glioblastoma multiforme (GBM) is the most deadly brain tumor, and it is characterized by extremely poor therapeutic response and overall survival. Adjuvant radiotherapy remains the standard of care following surgical resection. Thus, elucidating the mechanisms conferring radioresistance in GBM is extremely urgent. In the present study, miR-96 was demonstrated to be significantly upregulated in radioresistant GBM cells. Knockdown of miR-96 in the radioresistant GBM cells T98G elevated the % of apoptotic cells and reduced their clonogenic formation ability following radiotherapy. By contrast, overexpression of miR-96 in the radiosensitive GBM cells U87-MG reduced the % of apoptotic cells and increased their clonogenic formation ability following radiotherapy. Results from phosphorylated-H2A histone family member X (γH2AX) foci staining and comet assays revealed that miR-96 enhanced the DNA repair processes. Furthermore, miR-96 overexpression conferred radioresistance by downregulating programmed cell death protein 4 (PDCD4). Luciferase assay results revealed that miR-96 bound to the 3'UTR of PDCD4 mRNA. Finally, U87-MG cells regained radiosensitivity following PDCD4 overexpression. Taken together, the present is the first study to establish that upregulation of miR-96 in GBM cells confers radioresistance via targeting PDCD4, which might be a potential therapeutic target for GBM.

Exosomes Regulate the Transformation of Cancer Cells in Cancer Stem Cell Homeostasis

In different biological model systems, exosomes are considered mediators of cell-cell communication between different cell populations. Exosomes, as extracellular vesicles, participate in physiological and pathological processes by transmitting signaling molecules such as proteins, nucleic acids, and lipids. The tumor's microenvironment consists of many types of cells, including cancer stem cells and mesenchymal cells. It is well known that these cells communicate with each other and thereby regulate the progression of the tumor. Recent studies have provided evidence that exosomes mediate the interactions between different types of cells in the tumor microenvironment, providing further insight into how these cells interact through exosome signaling. Cancer stem cells are a small kind of heterogeneous cells that existed in tumor tissues or cancer cell lines. These cells possess a stemness phenotype with a self-renewal ability and multipotential differentiation which was considered the reason for the failure of conventional cancer therapies and tumor recurrence. However, a highly dynamic equilibrium was found between cancer stem cells and cancer cells, and this indicates that cancer stem cells are no more special target and blocking the transformation of cancer stem cells and cancer cells seem to be a more significant therapy strategy. Whether exosomes, as an information transforming carrier between cells, regulated cancer cell transformation in cancer stem cell dynamic equilibrium and targeting exosome signaling attenuated the formation of cancer stem cells and finally cure cancers is worthy of further study.

Exosomal miR-1246 in body fluids is a potential biomarker for gastrointestinal cancer

AIM

The aim was to systematically evaluate whether exosomal miRNAs could be regarded as potential minimally invasive biomarkers of diagnosis for gastrointestinal cancer.

METHODS

A systematic review and meta analysis of exosomal miRNA expression in gastrointestinal cancer were performed.

RESULTS

A total of 370 articles were retrieved from PubMed and EMBASE. The summary receiver operating characteristic curves of three miRNAs (miR-21, miR-1246 and miR-4644) were drawn, miR-21, miR-1246 and miR-4644 exhibited sensitivities of 0.66, 0.920 and 0.750, respectively; specificities were 0.87, 0.958 and 0.769, respectively; and areas under the curve for discriminating gastrointestinal cancer patients from control subjects were 0.876, 0.969 and 0.827, respectively.

CONCLUSION

Exosome miR-1246 had the highest level of diagnostic efficiency, which indicated that miR-1246 could be a biomarker.

Exosomal miR-21-5p derived from gastric cancer promotes peritoneal metastasis via mesothelial-to-mesenchymal transition

Peritoneal metastasis is a primary metastatic route for gastric cancers, and the mechanisms underlying this process are still unclear. Peritoneal mesothelial cells (PMCs) undergo mesothelial-to-mesenchymal transition (MMT) to provide a favorable environment for metastatic cancer cells. In this study, we investigated how the exosomal miR-21-5p induces MMT and promotes peritoneal metastasis. Gastric cancer (GC)-derived exosomes were identified by transmission electron microscopy and western blot analysis, then the uptake of exosomes was confirmed by PKH-67 staining. The expression of miR-21-5p and SMAD7 were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, and the interactions between miR-21-5p and its target genes SMAD7 were confirmed by Luciferase reporter assays. The MMT of PMCs was determined by invasion assays, adhesion assays, immunofluorescent assay, and western blot. Meanwhile, mouse model of tumor peritoneal dissemination model was performed to investigate the role of exosomal miR-21-5p in peritoneal metastasis in vivo. We found that PMCs could internalize GC-derived exosomal miR-21-5p and led to increased levels of miR-21-5p in PMCs. Through various types of in vitro and in vivo assays, we confirmed that exosomal miR-21-5p was able to induce MMT of PMCs and promote tumor peritoneal metastasis. Moreover, our study revealed that this process was promoted by exosomal miR-21-5p through activating TGF-β/Smad pathway via targeting SMAD7. Altogether, our data suggest that exosomal miR-21-5p induces MMT of PMCs and promote cancer peritoneal dissemination by targeting SMAD7. The exosomal miR-21-5p may be a novel therapeutic target for GC peritoneal metastasis.

Autophagic degradation of SQSTM1 inhibits ovarian cancer motility by decreasing DICER1 and AGO2 to induce MIRLET7A-3P

The relationship between macroautophagy/autophagy and miRNA in regulating cancer cell motility is not clearly delineated. Here, we found that induction of BECN1-dependent or -independent autophagy decreased ubiquitin-binding proteins SQSTM1/p62 and CALCOCO2/NDP52. Downregulation of SQSTM1 (but not CALCOCO2) led to a decrease of the miRNA-processing enzyme DICER1 and the miRNA effector AGO2. The autophagy-mediated reduction of levels of SQSTM1, DICER1 or AGO2 resulted in increased MIRLET7A-3P (but not MIRLET7A-5P or PRE-MIRLET7A miRNA) and suppressed ovarian cancer motility. The investigation of the MIRLET7A effects on cancer cell motility showed that synthetic MIRLET7A-3P (3 nM) inhibited, whereas MIRLET7A-5P (100 nM) increased cancer cell motility. Moreover, downregulation of MIRLET7A-3P with antisense of MIRLET7A-3P miRNA (MIRLET7A-3P inhibitor; 3 nM) reversed the nutrient depletion- and rVP1-mediated suppression of ovarian cancer cell motility. In addition, restoring SQSTM1, DICER1 and AGO2 with inhibition of autophagic degradation or overexpression of DICER1 and AGO2 reversed the autophagy-associated enhancement of MIRLET7A-3P and inhibition of motility. Examination of ovarian cancer tissue microarray further showed that the levels of SQSTM1, DICER1 and AGO2 in the tumor were higher than those in the non-tumor cells and negatively correlated with the levels of autophagy and MIRLET7A-3P. Our results demonstrated that induction of autophagy to decrease SQSTM1, DICER1 and AGO2 and increase MIRLET7A-3P is a potential therapeutic strategy for suppressing ovarian cancer cell motility. Abbreviations: ACTB: actin beta; AGO2: argonaute 2, RISC catalytic component; ATG: autophagy related; BCIP/NBT: 5-bromo-4-chloro-3-indolyl-phosphate/nitro blue tetrazolium; BECN1: beclin 1, autophagy related; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CQ: chloroquine; DICER1: dicer 1, ribonuclease III; EBSS: Earle balanced salt solution; FBS: fetal bovine serum; HGF: hepatocyte growth factor; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MIRLET7A: microRNA LET-7A: MIR16: microRNA 16; MIR29C: microRNA 29C; miRNA: microRNA; MMP: matrix metallopeptidase; PRE-MIRNA: precursor microRNA; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; RISC: RNA-induced silencing complex; rVP1: recombinant foot-and-mouth disease virus capsid protein VP1; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; WIPI: WD repeat domain, phosphoinositide interacting.

Emerging role of exosome signalling in maintaining cancer stem cell dynamic equilibrium

Cancer stem cells (CSCs) are a small subset of heterogeneous cells existed in tumour tissues or cancer cell lines with self-renewal and differentiation potentials. CSCs were considered to be responsible for the failure of conventional therapy and tumour recurrence. However, CSCs are not a static cell population, CSCs and non-CSCs are maintained in dynamic interconversion state by their self-differentiation and dedifferentiation. Therefore, targeting CSCs for cancer therapy is still not enough,exploring the mechanism of dynamic interconversion between CSCs and non-CSCs and blocking the interconversion seems to be imperative. Exosomes are 30-100 nm size in diameter extracellular vesicles (EVs) secreted by multiple living cells into the extracellular space. They contain cell-state-specific bioactive materials, including DNA, mRNA, ncRNA, proteins, lipids, etc. with their specific surface markers, such as, CD63, CD81, Alix, Tsg101, etc. Exosomes have been considered as information carriers in cell communication between cancer cells and non-cancer cells, which affect gene expressions and cellular signalling pathways of recipient cells by delivering their contents. Now that exosomes acted as information carriers, whether they played role in maintaining dynamic equilibrium state between CSCs and non-CSCs and their mechanism of activity are unknown. This review summarized the current research advance of exosomes' role in maintaining CSC dynamic interconversion state and their possible mechanism of action, which will provide a better understanding the contribution of exosomes to dedifferentiation and stemness acquisition of non-CSCs, and highlight that exosomes might be taken as the attractive target approaches for cancer therapeutics.

Contrast-enhanced computed tomography combined with Chitosan-Fe3O4 nanoparticles targeting fibroblast growth factor receptor and vascular endothelial growth factor receptor in the screening of early esophageal cancer

Esophageal cancer is a malignant tumor with a relatively high invasiveness, metastatic potential and worldwide incidence among human cancers. The majority of patients with esophageal cancer are diagnosed in a late tumor stage due to a lack of advanced and sensitive protocols for the diagnosis of patients with early-stage esophageal cancer. In the current study, contrast-enhanced computerized tomography (CECT) combined with Chitosan-Fe₃O₄ nanoparticles targeting fibroblast growth factor receptor (FGFR) and vascular endothelial growth factor receptor (VEGFR; CECT-CNFV) were used to diagnose patients with suspected esophageal cancer. A Chitosan-Fe₃O₄-parceled bispecific antibody targeting FGFR and VEGFR was produced and its affinity to esophageal cancer cells was determined both in vitro and in vivo. A total of 320 patients with suspected esophageal cancer were voluntarily recruited to evaluate the efficacy of CECT-CNFV in the diagnosis of early-stage esophageal cancer. All participants were subjected to CT and CECT-CNFV to detect whether tumors were present in the esophageal area. A Chitosan-Fe₃O₄ nanoparticles contrast agent was orally administered at 20 min prior to CT and CECT-CNFV. The results demonstrated that CECT-CNFV improved diagnostic sensitivity and provided a novel protocol for the diagnosis of tumors in patients with suspected gastric cancer at an early-stage. Furthermore, the resolution ratio of images was enhanced by CECT-CNFV, which enabled the visualization of tiny tumor nodules in esophageal tissue. Clinical data demonstrated that CECT-CNFV diagnosed 200 patients with suspected early-stage esophageal cancer and 120 patients as tumor free. In addition, CECT-CNFV exhibited higher signal enhancement of tumor nodules than CT, suggesting a higher accuracy and accumulation of nanoparticle contrast agent within the tumor nodules of esophageal tissue. Notably, the survival rate of patients with esophageal cancer diagnosed at an early-stage by CECT-CNFV was higher than the mean five-year survival rate (P<0.01). In conclusion, CECT-CNFV enhanced the sensitivity and accuracy of CT in the diagnosis of early-stage esophageal cancer. Thus, CECT-CNFV may improve the accuracy of CT in the diagnosis of mural enhancement in patients with esophageal cancer.

Exosomes in cancer: small vesicular transporters for cancer progression and metastasis, biomarkers in cancer therapeutics

Cancer progression is a polygenic procedure in which the exosomes can function as substantial roles. Exosomes are tiny, phospholipid bilayer membrane nanovesicles of endocytic derivation with a diameter of 40-100 nm. These nanovesicles can transport bioactive molecules containing mRNAs, proteins, DNA fragments, and non-coding RNAs from a donor cell to recipient cells, and cause the alteration in genetic and epigenetic factors and reprogramming of the target cells. Many diverse cell types such as mesenchymal cells, immune cells, and cancer cells can induce the release of exosomes. Increasing evidence illustrated that the exosomes derived from tumor cells might trigger the tumor initiation, tumor cell growth and progression, metastasis, and drug resistance. The secreted nanovesicles of exosomes can play significant roles in cells communicate via shuttling the nucleic acid molecules and proteins to target cells and tissues. In this review, we discussed multiple mechanisms related to biogenesis, load, and shuttle of the exosomes. Also, we illustrated the diverse roles of exosomes in several types of human cancer development, tumor immunology, angiogenesis, and metastasis. The exosomes may act as the promising biomarkers for the prognosis of various types of cancers which suggested a new pathway for anti-tumor therapeutic of these nanovesicles and promoted exosome-based cancer for clinical diagnostic and remedial procedures.

Neutral Sphingomyelinases in Cancer: Friend or Foe?

For many years, neutral sphingomyelinases (N-SMases) were long thought to be anticancer enzymes owing to their roles as key producers of ceramide linked to apoptosis, growth arrest, and the chemotherapeutic response. However, in recent years, with the cloning of multiple isoforms and with new information on their cellular roles, particularly for nSMase2, a more complex picture is emerging suggesting that N-SMases have both pro- and anticancer roles. In this chapter, we will summarize current knowledge on N-SMase expression in cancer and the roles of N-SMase activity and specific isoforms in cancer-relevant biologies. We will also discuss what we see as the major challenges ahead for research into N-SMases in cancer.

Changes in MiRNA-5196 Expression as a Potential Biomarker of Anti-TNF-α Therapy in Rheumatoid Arthritis and Ankylosing Spondylitis Patients

In this study, we analysed the expression level of sera circulating miRNA-5196 in rheumatoid arthritis (RA) and ankylosing spondylitis (AS) patients before and after tumor necrosis factor (TNF)-α therapy as biomarkers predicting positive treatment outcome. We enrolled 10 RA patients, 13 AS patients, and 12 healthy individuals in the study. The expression of miRNA-5196 was measured by real-time polymerase chain reaction before and after anti-TNF-α therapy. Disease activity of RA patients was assessed using disease activity score 28 (DAS28), whereas ankylosing spondylitis DAS (ASDAS) was used in AS patients. MiRNA-5196 expression was significantly higher in patients with RA and AS before TNF-α therapy than in those following anti-TNF-α therapy and healthy controls. Changes in miRNA-5196 expression positively correlated with delta DAS28 or delta ASDAS, respectively, following TNF-α therapy. In contrast, changes in C-reactive protein (CRP) levels in RA and AS patients did not positively correlate with DAS28 or ASDAS changes. Receiver-operating characteristic analysis showed better diagnostic accuracy of miRNA-5196 expression both in RA (area under curve (AUC) = 0.87, p = 0.055) and AS patients (AUC = 0.90, p = 0.050) compared to CRP levels in RA (AUC = 0.75, p = 0.201) and AS patients (AUC = 0.85, p = 0.086) upon biologic therapy treatment. Finding novel biomarkers, including miRNA-5196 which allow to predict and monitor anti-TNF-α response, would be of clinical value especially during the early phase of RA or AS development.

Exosomes Secreted by Adipose-Derived Stem Cells Contribute to Angiogenesis of Brain Microvascular Endothelial Cells Following Oxygen-Glucose Deprivation In Vitro Through MicroRNA-181b/TRPM7 Axis

Adipose-derived stem cells (ADSCs) have been demonstrated to promote cerebral vascular remodeling processes after stroke. However, the exact molecular mechanism by which ADSCs exert protective roles in ischemic stroke is still poorly understood. In this study, we identified the role of exosomal microRNA-181b-5p (181b-Exos) in regulating post-stroke angiogenesis. The results of migration assay and capillary network formation assay showed that exosomes secreted by ADSCs (ADSCs-Exos) promoted the mobility and angiogenesis of brain microvascular endothelial cells (BMECs) after oxygen-glucose deprivation (OGD). Quantitative real-time polymerase chain reaction (qRT-PCR) showed that microRNA-212-5p (miR-212-5p) and miR-181b-5p were upregulated in BMECs subjected to the brain extract of the middle cerebral artery occlusion rats. The migration distance and tube length were increased in BMECs cultured with 181b-Exos. Furthermore, we identified that transient receptor potential melastatin 7 (TRPM7) was a direct target of miR-181b-5p. TRPM7 mRNA and protein levels were declined in BMECs cultured with 181b-Exos, but not in BMECs cultured with 212-Exos. Overexpression of TRPM7 reversed the effects of 181b-Exos on migration and tube formation of BMECs. In addition, 181b-Exos upregulated the protein expression of hypoxia-inducible factor 1α and vascular endothelial cell growth factor, and downregulated the protein expression of tissue inhibitor of metalloproteinase 3. The regulatory effect of 181b-Exos was attenuated by overexpressing TRPM7. Altogether, ADSCs-Exos promote the angiogenesis of BMECs after OGD via miR-181b-5p/TRPM7 axis, suggesting that ADSCs-Exos may represent a novel therapeutic approach for stroke recovery.

Emerging role of exosome-derived long non-coding RNAs in tumor microenvironment

Exosomes are extracellular vesicles released by many cell types and have been attributed for their roles in many diseases including cancer. Exosomes secreted by tumor cells and stromal cells are critical mediators of intercellular communication in tumor microenvironments. Long noncoding RNAs (lncRNAs) are selectively sorted into exosomes and can regulate cancer onset and progression in a variety of ways. In this review, we summarize the characteristics of exosomal lncRNAs and their dysregulation in multiple types of cancer. We provide an overview of current research on exosomal lncRNAs in tumor microenvironments, especially the functions of exosomal lncRNAs in regulating tumor biology. A deeper understanding of the role of exosomal lncRNAs in the tumor microenvironment may help provide new diagnostic and prognostic markers for cancer.

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.

Comparative analysis of microRNA expression profiles between A549, A549/DDP and their respective exosomes

Exosomes were reported to transport bioactive molecules and influence the biology behavior of recipient cells. In order to study the role of exosomal microRNAs in the mechanism of cisplatin resistance to lung cancer cells, we analyzed the expression profiles of microRNAs in A549, A549/DDP cells and their exosomes by microarray. The results showed that a certain proportion of microRNAs were co-expressed in the cells and exosomes. Linear regression analysis showed that the expression of microRNAs in A549 and A549/DDP cells were strongly correlated with those in their respective exosomes. The expression level of 5 microRNAs (miR-197-5p, miR-4443, miR-642a-3p, miR-27b-3p and miR-100-5p) with the most differential expression were verified by qRT-PCR. The results were consistent with those of the microarray. Target gene prediction and pathway analysis discovered that the microRNAs in the intersections may participate in drug resistance. And the prediction of their association with diseases found that most of these microRNAs was associated with lung cancer. We could draw a preliminary conclusion that microRNAs in exosomes may be involved in the drug resistance of lung cancer cells to cisplatin.

The influence of tumour-derived extracellular vesicles on local and distal metastatic dissemination

Extracellular vesicles (EVs) are key mediators of intercellular communication that have been ignored for decades. Tumour cells benefit from the secretion of vesicles as they can influence the behaviour of neighbouring tumour cells within the tumour microenvironment. Several studies have shown that extracellular vesicles play an active role in pre-metastatic niche formation and importantly, they are involved in the metastatic organotropism of different tumour types. Tumour-derived EVs carry and transfer molecules to recipient cells, modifying their behaviour through a process defined as "EV-driven education". EVs favour metastasis to sentinel lymph nodes and distal organs by reinforcing angiogenesis, inflammation and lymphangiogenesis. Hence, in this review we will summarize the main mechanisms by which tumour-derived EVs regulate lymph node and distal organ metastasis. Moreover, since some cancers metastasize through the lymphatic system, we will discuss recent discoveries about the presence and function of tumour EVs in the lymph. Finally, we will address the potential value of tumour EVs as prognostic biomarkers in liquid biopsies, specially blood and lymphatic fluid, and the use of these tools as early detectors of metastases.