Emerging Function and Clinical Values of Exosomal MicroRNAs in Cancer. Mol Ther Nucleic Acids. 2019;16:791-804. [PMID: 31163321 PMCID: PMC6545365 DOI: 10.1016/j.omtn.2019.04.027]

The role of CAF derived exosomal microRNAs in the tumour microenvironment of melanoma

Exosomes play a crucial role in the crosstalk between cancer associated fibroblasts (CAFs) and cancer cells, contributing to carcinogenesis and the tumour microenvironment. Recent studies have revealed that CAFs, normal fibroblasts and cancer cells all secrete exosomes that contain miRNA, establishing a cell-cell communication network within the tumour microenvironment. For example, miRNA dysregulation in melanoma has been shown to promote CAF activation via induction of epithelial-mesenchymal transition (EMT), which in turn alters the secretory phenotype of CAFs in the stroma. This review assesses the roles of melanoma exosomal miRNAs in CAF formation and how CAF exosome-mediated feedback signalling to melanoma lead to tumour progression and metastasis. Moreover, efforts to exploit exosomal miRNA-mediated network communication between tumour cells and their microenvironment, and their potential as prognostic biomarkers or novel therapeutic targets in melanoma will also be considered.

MicroRNA-3613-5p Promotes Lung Adenocarcinoma Cell Proliferation through a RELA and AKT/MAPK Positive Feedback Loop

Aberrant activation of nuclear factor κB (NF-κB)/RELA is often found in lung adenocarcinoma (LUAD). In this study, we determined that microRNA-3613-5p (miR-3613-5p) plays a crucial role in RELA-mediated post-transcriptional regulation of LUAD cell proliferation. Expression of miR-3613-5p in clinical LUAD specimens is associated with poor prognosis in LUAD. Upregulation of miR-3613-5p promotes LUAD cell proliferation in vitro and in vivo. Our results suggested a mechanism whereby miR-3613-5p expression is induced by RELA through its direct interaction with JUN, thereby stimulating the AKT/mitogen-activated protein kinase (MAPK) pathway by directly targeting NR5A2. In addition, we also found that phosphorylation of AKT1 and MAPK3/1 co-transactivates RELA, thus constituting a RELA/JUN/miR-3613-5p/NR5A2/AKT1/MAPK3/1 positive feedback loop, leading to persistent NF-κB activation. Our findings also revealed that miR-3613-5p plays an oncogenic role in LUAD by promoting cell proliferation and acting as a key regulator of the positive feedback loop underlying the link between the NF-κB/RELA and AKT/MAPK pathways.

Statistical Analysis for Identifying Differentially MicroRNA in Serum Exosomes of Lead Workers

Exosomes can transmit central nervous system (CNS) information to the peripheral circulatory system through the brain barrier, and exosomes in the blood can also enter the central nervous system likewise. The components of exosomal contents play a pivotal role in cell signal communication, and thus, the transmission of exosomal content components is considered as a newly discovered method of long-distance communication between cells. The current is aimed to explore the changes of the exosomal microRNA group in the serum of lead-exposed workers, which might be involved in the lead-induced neuroinflammation, especially the activation of microglia and the release of inflammatory factors. We proposed a method combining statistical analysis and experiment according to the different expression of exosomal microRNA. Firstly, we divided workers into two groups, lead-exposed group and control group, and then questionnaires were used to obtain their basic information, and medical testing methods were used to obtain their serum exosomes. Secondly, principal component analysis was used to construct a comprehensive index of neurobehavioral function. Furthermore, volcano map and heatmap were used to display the differential gene distribution and correlation analysis of expression levels, respectively. Finally, two software applications, TargetScan and miRanda, were used to predict the target genes of the significantly different microRNAs, respectively, and the target genes predicted by the two software applications are screened according to the scoring standards of each software. Our results showed that 73 microRNAs were changed in the serum exosomes of lead-exposed worker, among which 48 microRNAs are upregulated and 25 microRNAs are downregulated. Moreover, the miR-124 and miR-506 were identified, and they might be involved in the process of lead-induced neuroinflammation.

Circulating MicroRNAs and Blood-Brain-Barrier Function in Breast Cancer Metastasis

Brain metastases are a major cause of death in breast cancer patients. A key event in the metastatic progression of breast cancer in the brain is the migration of cancer cells across the blood-brain barrier (BBB). The BBB is a natural barrier with specialized functions that protect the brain from harmful substances, including anti-tumor drugs. Extracellular vesicles (EVs) sequestered by cells are mediators of cell-cell communication. EVs carry cellular components, including microRNAs that affect the cellular processes of target cells. Here, we summarize the knowledge about microRNAs known to play a significant role in breast cancer and/or in the BBB function. In addition, we describe previously established in vitro BBB models, which are a useful tool for studying molecular mechanisms involved in the formation of brain metastases.

Extracellular Vesicles Loaded miRNAs as Potential Modulators Shared Between Glioblastoma, and Parkinson's and Alzheimer's Diseases

Glioblastoma (GBM) is the deadliest brain tumor. Its poor prognosis is due to cell heterogeneity, invasiveness, and high vascularization that impede an efficient therapeutic approach. In the past few years, several molecular links connecting GBM to neurodegenerative diseases (NDDs) were identified at preclinical and clinical level. In particular, giving the increasing critical role that epigenetic alterations play in both GBM and NDDs, we deeply analyzed the role of miRNAs, small non-coding RNAs acting epigenetic modulators in several key biological processes. Specific miRNAs, transported by extracellular vesicles (EVs), act as intercellular communication signals in both diseases. In this way, miRNA-loaded EVs modulate GBM tumorigenesis, as they spread oncogenic signaling within brain parenchyma, and control the aggregation of neurotoxic protein (Tau, Aβ-amyloid peptide, and α-synuclein) in NDDs. In this review, we highlight the most promising miRNAs linking GBM and NDDs playing a significant pathogenic role in both diseases.

Breast tumor cells promotes the horizontal propagation of EMT, stemness, and metastasis by transferring the MAP17 protein between subsets of neoplastic cells

MAP17 (PDZK1IP1) is a small protein regulating inflammation and tumor progression, upregulated in a broad range of carcinomas. MAP17 levels increase during tumor progression in a large percentage of advanced tumors. In the present work, we explored the role of this protein shaping tumor evolution. Here we show that in breast cancer, cells increased MAP17 levels in tumors by demethylation induced multiple changes in gene expression through specific miRNAs downregulation. These miRNA changes are dependent on Notch pathway activation. As a consequence, epithelial mesenchymal transition (EMT) and stemness are induced promoting the metastatic potential of these cells both in vitro and in vivo. Furthermore, MAP17 increased the exosomes in tumor cells, where MAP17 was released as cargo, and this horizontal propagation also increased the EMT in the recipient cells. Importantly, an antibody against MAP17 in the media reduces the EMT and stemness alterations promoted by the conditioned media from MAP17-expressing cells. Therefore, MAP17 expression promotes the horizontal propagation of EMT and metastasis by transferring the MAP17 protein between subsets of neoplastic cells. Thus, MAP17 can be used to describe a new mechanism for cell malignity at distance, without the involvement of genetic or epigenetic modifications. MAP17 can also be taken in consideration as new target for metastatic high-grade breast tumors.

Hijacking of Lipid Droplets by Hepatitis C, Dengue and Zika Viruses-From Viral Protein Moonlighting to Extracellular Release

Hijacking and manipulation of host cell biosynthetic pathways by human enveloped viruses are essential for the viral lifecycle. Flaviviridae members, including hepatitis C, dengue and Zika viruses, extensively manipulate host lipid metabolism, underlining the importance of lipid droplets (LDs) in viral infection. LDs are dynamic cytoplasmic organelles that can act as sequestration platforms for a unique subset of host and viral proteins. Transient recruitment and mobilization of proteins to LDs during viral infection impacts host-cell biological properties, LD functionality and canonical protein functions. Notably, recent studies identified LDs in the nucleus and also identified that LDs are transported extracellularly via an autophagy-mediated mechanism, indicating a novel role for autophagy in Flaviviridae infections. These developments underline an unsuspected diversity and localization of LDs and potential moonlighting functions of LD-associated proteins during infection. This review summarizes recent breakthroughs concerning the LD hijacking activities of hepatitis C, dengue and Zika viruses and potential roles of cytoplasmic, nuclear and extracellular LD-associated viral proteins during infection.

Cancer stem cell secretome in the tumor microenvironment: a key point for an effective personalized cancer treatment

Cancer stem cells (CSCs) represent a tumor subpopulation responsible for tumor metastasis and resistance to chemo- and radiotherapy, ultimately leading to tumor relapse. As a consequence, the detection and eradication of this cell subpopulation represent a current challenge in oncology medicine. CSC phenotype is dependent on the tumor microenvironment (TME), which involves stem and differentiated tumor cells, as well as different cell types, such as mesenchymal stem cells, endothelial cells, fibroblasts and cells of the immune system, in addition to the extracellular matrix (ECM), different in composition to the ECM in healthy tissues. CSCs regulate multiple cancer hallmarks through the interaction with cells and ECM in their environment by secreting extracellular vesicles including exosomes, and soluble factors such as interleukins, cytokines, growth factors and other metabolites to the TME. Through these factors, CSCs generate and activate their own tumor niche by recruiting stromal cells and modulate angiogenesis, metastasis, resistance to antitumor treatments and their own maintenance by the secretion of different factors such as IL-6, VEGF and TGF-ß. Due to the strong influence of the CSC secretome on disease development, the new antitumor therapies focus on targeting these communication networks to eradicate the tumor and prevent metastasis, tumor relapse and drug resistance. This review summarizes for the first time the main components of the CSC secretome and how they mediate different tumor processes. Lastly, the relevance of the CSC secretome in the development of more precise and personalized antitumor therapies is discussed.

Enzyme-Free Electrochemical Biosensor Based on Localized DNA Cascade Displacement Reaction and Versatile DNA Nanosheets for Ultrasensitive Detection of Exosomal MicroRNA

MicroRNA existing in exosomes (exo-miRNA) is a crucial and reliable biomarker for cancer screening and diagnosis. However, accurate detection of ultralow exo-miRNA amounts in real samples remains a challenge. Herein, a robust and ultrasensitive electrochemical biosensor was developed based on localized DNA cascade displacement reaction (L-DCDR) and versatile DNA nanosheets (DNSs) for enzyme-free analysis of exo-miRNA. The target activated L-DCDR repeatedly by consecutive toehold-mediated strand displacement, which released plentiful P strands to hybridize with capture probes immobilized on the electrode surface and DNS tags, generating an amplified electrochemical signal for the detection of exo-miRNA. The DNS could label-free load various electroactive molecules. The electrochemical biosensor revealed high sensitivity ranging from 0.1 fM to 1 nM with a limit of detection of 65 aM and good specificity. The constructed biosensor was demonstrated to be able to detect exo-miRNA derived from gastric cancer cell line (SGC-7901) and gastric cancer patients. In addition, the developed biosensor possessed several considerable advantages including simple substrate assembly, improved reaction rate, and high signal-to-noise ratio. Therefore, this strategy has great potential in bioanalysis and clinical diagnostics.

MicroRNA-7 regulates the proliferation and metastasis of human papillary carcinoma cells by targeting Bcl-2

Papillary carcinoma is the most common type of thyroid cancer responsible for significant number of mortalities across the globe. This study was conducted to investigate the role and therapeutic implications of microRNA-7 in human papillary carcinoma. Gene expression analysis was carried out through quantitative real time PCR method. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to determine the cell proliferation. Clonogenic assay was used to assess the colony forming ability of cancer cells. Cell apoptosis was analyzed by 4',6-diamidino-2-phenylindole (DAPI), acridine orange/ethidium bromide (AO/EB) and annexin V/PI staining assays. Migration of cancer cells was estimated through scratch heal assay and cell invasion was determined by transwell assay method. Western blotting was done to examine the protein expression. Xenografted mice models were employed to examine the effects of miR-7 overexpression in vivo. Results showed miR-7 to be significantly (P < 0.05) repressed in papillary carcinoma. Cancer cell proliferation was inhibited by miR-7 through induction of apoptotic cell death as revealed by DAPI, AO/EB and annexin V/PI staining assays. The colony forming potential of cancer cells also decreased under miR-7 overexpression. miR-7 overexpression also inhibited the migration and invasion of cancer cells. Bcl-2 was identified as the intracellular target of miR-7 and regulatory effects of miR-7 were seen to be exerted through translation repression of Bcl-2. The results of xenograft study revealed miR-7 overexpression significantly (P < 0.05) suppressed the growth of the tumor in vivo. The results point towards the therapeutic implications of miR-7 in the management of papillary carcinoma.

MicroRNAs in Chronic Kidney Disease: Four Candidates for Clinical Application

There are still major challenges regarding the early diagnosis and treatment of chronic kidney disease (CKD), which is in part due to the fact that its pathophysiology is very complex and not clarified in detail. The diagnosis of CKD commonly is made after kidney damage has occurred. This highlights the need for better mechanistic insight into CKD as well as improved clinical tools for both diagnosis and treatment. In the last decade, many studies have focused on microRNAs (miRs) as novel diagnostic tools or clinical targets. MiRs are small non-coding RNA molecules that are involved in post-transcriptional gene regulation and many have been studied in CKD. A wide array of pre-clinical and clinical studies have highlighted the potential role for miRs in the pathogenesis of hypertensive nephropathy, diabetic nephropathy, glomerulonephritis, kidney tubulointerstitial fibrosis, and some of the associated cardiovascular complications. In this review, we will provide an overview of the miRs studied in CKD, especially highlighting miR-103a-3p, miR-192-5p, the miR-29 family and miR-21-5p as these have the greatest potential to result in novel therapeutic and diagnostic strategies.

Exosomics

Extracellular vesicles have been the focus of a large number of studies in the past five years. Exosomes, a subgroup of extracellular vesicles, are of particularly high interest because they partake in a wide number of biological pathways. Produced by a variety of cells, exosomes have an important role in both physiological and pathological conditions. Exosome cargo heavily defines the vesicles’ unique characteristics, and the cargo with the most intriguing prospects in its’ biomedical applications is the non-coding RNAs. Non-coding RNAs, and specifically microRNAs are implicated in the regulation of many biological processes and have been associated with numerous diseases. Exosomes containing such important cargo can be used as biomarkers, therapeutic biomaterials, or even drug carriers. The potential media use of exosomes seems promising. However, some obstacles should be overcome before their clinical application. Synthetic exosome-like biomolecules may be a solution, but their production is still in their beginning stages. This review provides concise information regarding the current trends in exosome studies.

Exosomal MicroRNAs and Organotropism in Breast Cancer Metastasis

Breast cancer is the most frequent malignancy for women in which one in eight women will be diagnosed with the disease in their lifetime. Despite advances made in treating primary breast cancer, there is still no effective treatment for metastatic breast cancer. Consequently, metastatic breast cancer is responsible for 90% of breast cancer-related deaths while only accounting for approximately one third of all breast cancer cases. To help develop effective treatments for metastatic breast cancer, it is important to gain a deeper understanding of the mechanisms by which breast cancer metastasizes, particularly, those underlying organotropism towards brain, bone, and lungs. In this review, we will primarily focus on the roles that circulating exosomal microRNAs (miRNAs) play in organotropism of breast cancer metastasis. Exosomes are extracellular vesicles that play critical roles in intercellular communication. MicroRNAs can be encapsulated in exosomes; cargo-loaded exosomes can be secreted by tumor cells into the tumor microenvironment to facilitate tumor-stroma interactions or released to circulation to prime distant organs for subsequent metastasis. Here, we will summarize our current knowledge on the biogenesis of exosomes and miRNAs, mechanisms of cargo sorting into exosomes, the exosomal miRNAs implicated in breast cancer metastasis, and therapeutic exosomal miRNAs.

Rapid Development of Targeting circRNAs in Cardiovascular Diseases

Circular RNAs (circRNAs) are circularized, single-stranded RNAs that are covalently linked. With their abundance in tissues and developmental stage-specific expression, circRNAs participate in a variety of physiological and pathological processes. In this review, we discuss the development of circRNAs used as biomarkers and therapeutic targets for cardiovascular diseases (CVDs), focusing on recent discoveries and applications of exosomal circRNAs that highlight opportunities and challenges. Some studies have identified a spectrum of circRNAs that are differentially expressed in CVDs, while other studies further manipulated specific circRNA expression and showed an ameliorated pathogenic state such as ischemic injury, hypertrophy, and cardiac fibrosis. Studies and applications of circRNAs are being rapidly developed. We expect to see clinical use of circRNAs as biomarkers and targets for disease treatment in the near future.

Defining lung cancer stem cells exosomal payload of miRNAs in clinical perspective

Since the first publication regarding the existence of stem cells in cancer [cancer stem cells (CSCs)] in 1994, many studies have been published providing in-depth information about their biology and function. This research has paved the way in terms of appreciating the role of CSCs in tumour aggressiveness, progression, recurrence and resistance to cancer therapy. Targeting CSCs for cancer therapy has still not progressed to a sufficient degree, particularly in terms of exploring the mechanism of dynamic interconversion between CSCs and non-CSCs. Besides the CSC scenario, the problem of cancer dissemination has been analyzed in-depth with the identification and isolation of microRNAs (miRs), which are now considered to be compelling molecular markers in the diagnosis and prognosis of tumours in general and specifically in patients with non-small cell lung cancer. Paracrine release of miRs via “exosomes” (small membrane vesicles (30-100 nm), the derivation of which lies in the luminal membranes of multi-vesicular bodies) released by fusion with the cell membrane is gaining popularity. Whether exosomes play a significant role in maintaining a dynamic equilibrium state between CSCs and non-CSCs and their mechanism of activity is as yet unknown. Future studies on CSC-related exosomes will provide new perspectives for precision-targeted treatment strategies.

Decreased miR-200b-3p in cancer cells leads to angiogenesis in HCC by enhancing endothelial ERG expression

Transcription factor ERG (erythroblast transformation-specific (ETS)-related gene) is essential in endothelial differentiation and angiogenesis, in which microRNA (miR)-200b-3p targeting site is expected by miRNA target prediction database. miR-200b is known decreased in hepatocellular carcinoma (HCC), however, the functional relation between ERG and miR-200b-3p, originating from pre-miR-200b, in HCC angiogenesis remains unclear. We investigated whether hepatocyte-derived miR-200b-3p governs angiogenesis in HCC by targeting endothelial ERG. Levels of miR-200b-3p in HCC tissues were significantly lower than those in adjacent non-HCC tissues. Poorly differentiated HCC cell line expressed lower level of miR-200b-3p compared to well-differentiated HCC cell lines. The numbers of ERG-positive endothelial cells were higher in HCC tissues than in adjacent non-HCC tissues. There was a negative correlation between the number of ERG-positive cells and miR-200b-3p expression in HCC tissues. Culture supernatants of HCC cell lines with miR-200b-3p-overexpression reduced cell migration, proliferation and tube forming capacity in endothelial cells relative to the control, while those with miR-200b-3p-inhibition augmented the responses. Exosomes isolated from HCC culture supernatants with miR-200b-3p overexpression suppressed endothelial ERG expression. These results suggest that exosomal miR-200b-3p from hepatocytes suppresses endothelial ERG expression, and decreased miR-200b-3p in cancer cells promotes angiogenesis in HCC tissues by enhancing endothelial ERG expression.

Circulating exosomal microRNAs as novel potential detection biomarkers in pancreatic cancer

Circulating exosomal microRNAs (ex-miRNAs) are reflective of the characteristics of the tumor and are valuable biomarkers in different types of tumor. In addition, miRNAs serve important roles in tumor progression and metastasis. The present study aimed to investigate the circulating ex-miRNA-21 and miRNA-210 as novel biomarkers for patients with pancreatic cancer (PC). For this purpose, serum ex-miRNAs were extracted from the serum of patients with PC (n=30) and chronic pancreatitis (CP) (n=10) using an RNA isolation kit. For exosome identification in serum, transmission electron micrographs were used to determine crystalline structure, western blotting was used to identify exosomal markers, and NanoSight was used for nanoparticle characterization. The relative expression levels of ex-miRNAs were quantified using quantitative PCR and compared between patients with PC and CP. The expression levels of both ex-miRNA-21 and miRNA-210 were significantly higher in patients with PC compared with patients with CP (both P<0.001). However, no significant difference in the relative serum levels of free miR-21 and miR-210 was observed between the 2 groups of patients (both P>0.05). ex-miRNA-21 and miRNA-210 were associated with tumor stage, as well as other factors. The diagnostic potential of ex-miRNA-21 and miRNA-210 levels was 83 and 85%, respectively. In addition, when ex-miRNA and serum carbohydrate antigen 19-9 expression levels were combined, the accuracy increased to 90%. The present study identified that serum ex-miRNAs, miRNA-21 and miRNA-210 may be of value as potential biomarkers and therapeutic targets for the diagnosis and treatment of PC.

P53: A Guardian of Immunity Becomes Its Saboteur through Mutation

Awareness of the importance of immunity in controlling cancer development triggered research into the impact of its key oncogenic drivers on the immune response, as well as their value as targets for immunotherapy. At the heart of tumour suppression is p53, which was discovered in the context of viral infection and now emerges as a significant player in normal and cancer immunity. Wild-type p53 (wt p53) plays fundamental roles in cancer immunity and inflammation. Mutations in p53 not only cripple wt p53 immune functions but also sinisterly subvert the immune function through its neomorphic gain-of-functions (GOFs). The prevalence of mutant p53 across different types of human cancers, which are associated with inflammatory and immune dysfunction, further implicates mutant p53 in modulating cancer immunity, thereby promoting tumorigenesis, metastasis and invasion. In this review, we discuss several mutant p53 immune GOFs in the context of the established roles of wt p53 in regulating and responding to tumour-associated inflammation, and regulating innate and adaptive immunity. We discuss the capacity of mutant p53 to alter the tumour milieu to support immune dysfunction, modulate toll-like receptor (TLR) signalling pathways to disrupt innate immunity and subvert cell-mediated immunity in favour of immune privilege and survival. Furthermore, we expose the potential and challenges associated with mutant p53 as a cancer immunotherapy target and underscore existing therapies that may benefit from inquiry into cancer p53 status.

Exosomal miRNAs in tumor microenvironment

Tumor microenvironment (TME) is the internal environment in which tumor cells survive, consisting of tumor cells, fibroblasts, endothelial cells, and immune cells, as well as non-cellular components, such as exosomes and cytokines. Exosomes are tiny extracellular vesicles (40-160nm) containing active substances, such as proteins, lipids and nucleic acids. Exosomes carry biologically active miRNAs to shuttle between tumor cells and TME, thereby affecting tumor development. Tumor-derived exosomal miRNAs induce matrix reprogramming in TME, creating a microenvironment that is conducive to tumor growth, metastasis, immune escape and chemotherapy resistance. In this review, we updated the role of exosomal miRNAs in the process of TME reshaping.

Exosomes as a Multicomponent Biomarker Platform in Cancer

Cancer is a complex disease that is associated with genetic aberrations and subsequent cellular and noncellular host responses. Tumors harbor diverse cell types that engage in a dynamic interplay to sustain cancer-specific signaling networks. A component of such cellular communication is the production and exchange of various types of extracellular vesicle (EV). Exosomes are small EVs with growing recognition for their role in cancer progression and resistance to therapy. The unique biogenesis of exosomes, their ubiquitous production by all cell types, and their biological features in liquid biopsies have generated excitement for their potential as cancer biomarkers. Here, we discuss the challenges and utility of exosomes as multiparameter biomarker platforms for the detection of cancer. Exosomes reflect heterogeneous biological changes associated with growing tumors, potentially offering a more comprehensive assessment of cancer diagnosis, prognosis, and progression.

The Role of Circulating MicroRNA in Glioblastoma Liquid Biopsy

Glioblastoma multiforme (GBM) is the most common and aggressive primary malignancy of the central nervous system. The standard used to monitor disease progression and therapeutic response has been magnetic resonance imaging, which is usually obtained preoperatively and postoperatively. Patients with GBM are monitored every 2-3 months and scans are repeated until progression is detected. Sometimes there is an inability to detect tumor progression or difficulty in differentiating tumor progression from pseudoprogression. With the difficulty of distinguishing disease progression, as well as the cost of imaging, there may be a need for the existence of a noninvasive liquid biopsy. There is no reliable biomarker for GBM that can be used for liquid biopsy, but if one could be detected in serum or cerebrospinal fluid and vary with tumor burden, then, it could be developed into one. MicroRNAs (miRNAs) are short, single-stranded, noncoding RNAs that posttranscriptionally control gene expression. They play vital roles in tumor progression, migration, invasion, and stemness. Because miRNAs are secreted in stable forms in bodily fluid, either via extracellular vesicles or in cell-free form, they have great potential as biomarkers that can be used for liquid biopsy. Various miRNAs that are dysregulated in GBM have been identified in tissue, cerebrospinal fluid, and serum samples. There needs to be standardization of sample collection and quantification for both cell-free and exosomal-derived samples. Further studies need to be performed on larger cohorts to evaluate the sensitivity and specificity of not just miRNAs but most potential biomarkers.

miR-1254 inhibits progression of glioma in vivo and in vitro by targeting CSF-1

The role of miRNAs (microRNAs) has been implicated in glioma initiation and progression, although the inherent biochemical mechanisms still remain to be unravelled. This study strived to evaluate the association between CSF-1 and miR-1254 and their effect on advancement of glioma cells. The levels of miR-1254 in glioma cells and tissues were determined by real-time RT-PCR. Proliferation, apoptosis and cell cycle arrest, invasion and migration, were assessed by CCK-8 assay, colony formation assay, flow cytometry, transwell assay and wound-healing assay, respectively. The targeted relationship between miR-1254 and CSF-1 was confirmed by dual-luciferase reporter assay. The effects of CSF-1 on cellular functions were also assessed. The in vivo effect of miR-1254 on the formation of a tumour was explored by using the mouse xenograft model. We found in both glioma tissues and glioma cells, the down-regulated expressions of miR-1254 while that of CSF-1 was abnormally higher than normal level. The target relationship between CSF-1 and miR-1254 was validated by dual-luciferase reporter assay. The CSF-1 down-regulation or miR-1254 overexpression impeded the invasion, proliferation and migratory ability of U251 and U87 glioma cells, concurrently occluded the cell cycle and induced cell apoptosis. Moreover, in vivo tumour development was repressed due to miR-1254 overexpression. Thus, CSF-1 is targeted directly by miR-1254, and the miR-1254/CSF-1 axis may be a potential diagnostic target for malignant glioma.

Manipulating microRNAs for the Treatment of Malignant Pleural Mesothelioma: Past, Present and Future

microRNAs (miRNAs) are an important class of non-coding RNA that post-transcriptionally regulate the expression of most protein-coding genes. Their aberrant expression in tumors contributes to each of the hallmarks of cancer. In malignant pleural mesothelioma (MPM), in common with other tumor types, changes in miRNA expression are characterized by a global downregulation, although elevated levels of some miRNAs are also found. While an increasing number of miRNAs exhibit altered expression in MPM, relatively few have been functionally characterized. Of a growing number with tumor suppressor activity in vitro, miR-16, miR-193a, and miR-215 were also shown to have tumor suppressor activity in vivo. In the case of miR-16, the significant inhibitory effects on tumor growth following targeted delivery of miR-16-based mimics in a xenograft model was the basis for a successful phase I clinical trial. More recently overexpressed miRNAs with oncogenic activity have been described. Many of these changes in miRNA expression are related to the characteristic loss of tumor suppressor pathways in MPM tumors. In this review we will highlight the studies providing evidence for therapeutic effects of modulating microRNA levels in MPM, and discuss these results in the context of emerging approaches to miRNA-based therapy.

Circular RNA circMAN2B2 promotes growth and migration of gastric cancer cells by down-regulation of miR-145

Background

CircMAN2B2 is a newly discovered circRNA that has been found to be an oncogene in lung cancer and glioma. The present study was designed to reveal the role of circMAN2B2 in gastric carcinoma (GC).

Methods

qRT‐PCR method was utilized to examine circMAN2B2 expression in GC tissues and paracancerous tissues. Next, circMAN2B2 expression in SNU‐16 and AGS cells was silenced by transfection. CCK‐8 assay, colony formation assay, flow cytometer, Transwell assay, and Western blot were conducted for testing cell phenotype changes. Further, the downstream genes and signaling were uncovered by qRT‐PCR and Western blot.

Results

As relative to paracancerous tissues, circMAN2B2 was high‐expressed in GC tissues. Silence of circMAN2B2 clearly declined SNU‐16 and AGS cells viability, survival, migration but enhanced apoptosis. Meanwhile, silence of circMAN2B2 induced the cleavage of caspases (−3 and −9), down‐regulation of MMPs (−2 and −9), and up‐regulation of miR‐145. The impacts of circMAN2B2 silence toward SNU‐16 and AGS cells were attenuated by miR‐145 silence. Moreover, circMAN2B2 silence deactivated PI3K, AKT while activated JNK through regulating miR‐145.

Conclusion

This work presented the oncogenic function of circMAN2B2 in GC cells growth and migration. CircMAN2B2 exerted its function possibly through regulating miR‐145 as well as PI3K/AKT and JNK pathways.

Exosomal miR-106b serves as a novel marker for lung cancer and promotes cancer metastasis via targeting PTEN

As novel non-invasive tumor diagnostic biomarkers, exosomal bioactive miRNAs have received increasing attention. Herein, the aim of this study is to explore the clinical values and roles of exosomal miR106b in lung cancer. The exosomal miR-106b level was much higher in the serum of patients with lung cancer than that in healthy volunteers. Also, the exosomal miR-106b level in the lung cancer patient serum was associated with TNM stages and lymph node metastasis. Furthermore, exosomal miR-106b enhanced the migrated and invasive ability of lung cancer cells and increased the MMP-2 and MMP-9 expression. Mechanistically, exosomal miR-106b could target PTEN, and promote lung cancer cell migration and invasion. More importantly, PTEN overexpression reversed the effect of exosomal miR-106b on lung cancer cell migration and invasion. Taken together, these findings indicate that exosomal miR-106b may be a promising diagnostic biomarker and drug target for patients with lung cancer.

Extracellular Vesicles with Possible Roles in Gut Intestinal Tract Homeostasis and IBD

The intestinal tract consists of various types of cells, such as epithelial cells, Paneth cells, macrophages, and lymphocytes, which constitute the intestinal immune system and play a significant role in maintaining intestinal homeostasis by producing antimicrobial materials and controlling the host-commensal balance. Various studies have found that the dysfunction of intestinal homeostasis contributes to the pathogenesis of inflammatory bowel disease (IBD). As a novel mediator, extracellular vesicles (EVs) have been recognized as effective communicators, not only between cells but also between cells and the organism. In recent years, EVs have been regarded as vital characters for dysregulated homeostasis and IBD in either the etiology or the pathology of intestinal inflammation. Here, we review recent studies on EVs associated with intestinal homeostasis and IBD and discuss their source, cargo, and origin, as well as their therapeutic effects on IBD, which mainly include artificial nanoparticles and EVs derived from microorganisms.

Exosome-encapsulated miRNAs contribute to CXCL12/CXCR4-induced liver metastasis of colorectal cancer by enhancing M2 polarization of macrophages

Tumor-associated macrophages (TAMs) are important immunocytes associated with cancer metastasis. However, whether TAMs play a dominant role in mediating CXCL12/CXCR4-induced liver metastasis of colorectal cancer (CRC) remains unexplored. Herein, we found that CD206⁺ TAMs, which infiltrated at the invasive front, were correlated with CXCR4 expression and liver metastasis of CRC in clinical specimens. Several miRNAs (miR-25-3p, miR-130b-3p, miR-425-5p), upregulated in CRC cells by activation of the CXCL12/CXCR4 axis, could be transferred to macrophages via exosomes. These exosomal miRNAs induced M2 polarization of macrophages by regulating PTEN through activation of PI3K/Akt signaling pathway. In turn, M2 polarized macrophages promoted cancer metastasis by enhancing epithelial-mesenchymal transition (EMT) and secreting vascular endothelial growth factor (VEGF). Co-culture of CRC cells with macrophages transfected with these miRNAs or treated with exosomes enhanced their metastatic capacity both in vitro and in vivo. Clinically, the serum levels of exosomal miR-25-3p, miR-130b-3p and miR-425-5p were correlated with progression and metastasis of CRC. In conclusion, these results reveal a crucial role of exosomal miRNAs in mediating the crosstalk between CXCR4 overexpressing cancer cells and TAMs, providing potential therapeutic targets for circumventing liver metastasis of CRC.

MicroRNA-9 and breast cancer

Breast cancer is the most common cancer in women worldwide and seriously impairs patients' physical and mental health. Its incidence has been predicted to rise further. Mounting evidence indicates that microRNAs (miRNAs) play key roles in tumorigenesis and development. It is worth noting that miR-9 exerts critical functions in the initiation and progression of breast cancer, and the present research displays opposite roles of miR-9 in breast cancer. This article mainly reviews the roles of miR-9 in breast cancer progression.

Technological Challenges and Future Issues for the Detection of Circulating MicroRNAs in Patients With Cancer

In the era of precision medicine, the success of clinical trials, notably for patients diagnosed with cancer, strongly relies on biomarkers with pristine clinical value but also on robust and versatile analytical technologies to ensure proper patients' stratification and treatment. In this review, we will first address whether plasmatic and salivary microRNAs can be considered as a reliable source of biomarkers for cancer diagnosis and prognosis. We will then discuss the pre-analytical steps preceding miRNA quantification (from isolation to purification), and how such process could be biased and time-consuming. Next, we will review the most recent tools derived from micro- and nano-technologies for microRNA detection available to date and how they may compete with current standards. This review will prioritize publications using relevant biological samples. The significance of various physical transduction schemes (mechanical, optical, electrical, etc.) for biological detection will be compared, and pros and cons of each method will be widely discussed. Finally, we will debate on how micro and nanotechnologies could widespread the use of biomarkers in modern medicine, to help manage patients with serious diseases such as cancer.

MicroRNAs in Pancreatic Cancer: biomarkers, prognostic, and therapeutic modulators

A severe lack of early diagnosis coupled with resistance to most available therapeutic options renders pancreatic cancer as a major clinical concern. The limited efficacy of current treatments necessitates the development of novel therapeutic strategies that are based on an understanding of the molecular mechanisms involved in pancreatic cancer progression. MicroRNAs (miRNAs) are non-coding small RNAs that regulate the expression of multiple proteins in the post-translation process and thus have promise as biomarkers, prognostic agents, and as advanced pancreatic therapies. Profiling of deregulated miRNAs in pancreatic cancer can correlate to diagnosis, indicate optimal treatment and predict response to therapy. Furthermore, understanding the main effector genes in pancreatic cancer along with downstream pathways can identify possible miRNAs as therapeutic candidates. Additionally, obstacles to the translation of miRNAs into the clinic are also considered. Distinct miRNA expression profiles can correlate to stages of malignant pancreatic disease, and hold potential as biomarkers, prognostic markers and clinical targets. However, a limited understanding and validation of the specific role of such miRNAs stunts clinical application. Target prediction using algorithms provides a wide range of possible targets, but these miRNAs still require validation through pre-clinical studies to determine the knock-on genetic effects.

The Role of Exosomal MicroRNAs in the Tumor Microenvironment of Breast Cancer

Breast cancer, ranking first among women's cancers worldwide, develops from the breast tissue. Study of the breast tissue is, therefore of great significance to the diagnosis and treatment of breast cancer. Exosomes, acting as an effective communicator between cells, are in the ascendant in recent years. One of the most important cargoes contained in the exosomes is microRNAs, belonging to the non-coding RNA family. When the exosomal microRNAs are absorbed into the intracellular location, most of the microRNAs will act as tumor promoters or suppressors by inhibiting the translation process of the target mRNA, thus affecting the behavior of other stromal cells in the tumor microenvironment. At present, growing research focuses on the different types of donor cell sources, their contribution to cancer, miRNA profiling, their biomarker potential, etc. This review aims to state the function of diverse miRNAs in exosomes medicated cell-cell communication and the potency of some specific enriched miRNAs as molecular markers in clinical trials. We also describe the mechanism of anti-cancer compounds through exosomes and the exploration of artificially engineered techniques that lead miRNA-inhibitors into exosomes for therapeutic use.