Hypoxia-induced microRNA-424 expression in human endothelial cells regulates HIF-α isoforms and promotes angiogenesis

MicroRNA-135a-3p regulates angiogenesis and tissue repair by targeting p38 signaling in endothelial cells

Angiogenesis is a critical process in repair of tissue injury that is regulated by a delicate balance between pro- and antiangiogenic factors. In disease states associated with impaired angiogenesis, we identified that miR-135a-3p is rapidly induced and serves as an antiangiogenic microRNA (miRNA) by targeting endothelial cell (EC) p38 signaling in vitro and in vivo. MiR-135a-3p overexpression significantly inhibited EC proliferation, migration, and network tube formation in matrigel, whereas miR-135-3p neutralization had the opposite effects. Mechanistic studies using transcriptomic profiling, bioinformatics, 3'-UTR reporter and miRNA ribonucleoprotein complex -immunoprecipitation assays, and small interfering RNA dependency studies revealed that miR-135a-3p inhibits the p38 signaling pathway in ECs by targeting huntingtin-interacting protein 1 (HIP1). Local delivery of miR-135a-3p inhibitors to wounds of diabetic db/db mice markedly increased angiogenesis, granulation tissue thickness, and wound closure rates, whereas local delivery of miR-135a-3p mimics impaired these effects. Finally, through gain- and loss-of-function studies in human skin organoids as a model of tissue injury, we demonstrated that miR-135a-3p potently modulated p38 signaling and angiogenesis in response to VEGF stimulation by targeting HIP1. These findings establish miR-135a-3p as a pivotal regulator of pathophysiological angiogenesis and tissue repair by targeting a VEGF-HIP1-p38K signaling axis, providing new targets for angiogenic therapy to promote tissue repair.-Icli, B., Wu, W., Ozdemir, D., Li, H., Haemmig, S., Liu, X., Giatsidis, G., Cheng, H. S., Avci, S. N., Kurt, M., Lee, N., Guimaraes, R. B., Manica, A., Marchini, J. F., Rynning, S. E., Risnes, I., Hollan, I., Croce, K., Orgill, D. P., Feinberg, M. W. MicroRNA-135a-3p regulates angiogenesis and tissue repair by targeting p38 signaling in endothelial cells.

Identification of exosomal and non‑exosomal microRNAs associated with the drug resistance of ovarian cancer

MicroRNAs (miRNAs) serve important roles in drug‑resistance; however, exosomal miRNAs associated with drug‑resistance in ovarian cancer (OC) have not been reported to date. The current study aimed to analyze the drug resistance‑associated exosomal miRNAs in original OC cells and their derived exosomes using microarray data downloaded from the Gene Expression Omnibus database (series GSE76449). The chemosensitive OC cell lines SKOV3_ip1, A2780_PAR and HEYA8, as well as the chemoresistant cell lines SKOV3_TR, A2780_CP20 and HEYA8_MDR, were investigated. Differentially expressed miRNAs (DE‑miRNAs) were identified using the limma method, and their mRNA targets were predicted using the miRWalk and LinkedOmics database. Functions of target genes were analyzed with DAVID tool, while TCGA data were used to explore the survival association of identified miRNAs. According to the results, 28 DE‑miRNAs were found to be common in exosomal and original samples of A2780_CP20 cells, among which the functions of 5 miRNAs were predicted (including miR‑146b‑5p, miR‑509‑5p, miR‑574‑3p, miR‑574‑5p and miR‑760). In addition, 16 and 35 DE‑miRNAs were detected for HEYA8_MDR and SKOV3_TR, respectively, with the functions of 4 of these miRNAs predicted for each cell line (HEYA8_MDR: miR‑30a‑3p, miR‑30a‑5p, miR‑612 and miR‑617; SKOV3_TR: miR‑193a‑5p, miR‑423‑3p, miR‑769‑5p and miR‑922). It was also reported that miR‑183‑5p was the only one common miRNA among the three cell lines. Furthermore, miR‑574‑3p, miR‑30a‑5p and miR‑922 may regulate CUL2 to mediate HIF‑1 cancer signaling pathway, while miR‑183‑5p may modulate MECP2, similar to miR‑760, miR‑30a‑5p and miR‑922, to influence cell proliferation. Finally, the downregulated miR‑612 may promote the expression of TEAD3 via the Hippo signaling pathway, and this miRNA was associated with poor prognosis. In conclusion, the findings of the present study suggested several underlying miRNA targets for improving the chemotherapy sensitivity of OC.

H19X-encoded miR-424(322)/-503 cluster: emerging roles in cell differentiation, proliferation, plasticity and metabolism

miR-424(322)/-503 are mammal-specific members of the extended miR-15/107 microRNA family. They form a co-expression network with the imprinted lncRNA H19 in tetrapods. miR-424(322)/-503 regulate fundamental cellular processes including cell cycle, epithelial-to-mesenchymal transition, hypoxia and other stress response. They control tissue differentiation (cardiomyocyte, skeletal muscle, monocyte) and remodeling (mammary gland involution), and paradoxically participate in tumor initiation and progression. Expression of miR-424(322)/-503 is governed by unique mechanisms involving sex hormones. Here, we summarize current literature and provide a primer for future endeavors.

Tumor suppressor miR-215 counteracts hypoxia-induced colon cancer stem cell activity

Cancer stem cells, also known as tumor-initiating cells (TICs), are a population of aggressive and self-renewing cells that are responsible for the initiation and progression of many cancers, including colorectal carcinoma. Intratumoral hypoxia, i.e. reduced oxygen supply following uncontrolled proliferation of cancer cells, is thought to support TIC activity by inducing specific hypoxia-responsive mechanisms that are not yet entirely understood. Using previously established and fully characterized patient-derived TIC cultures, we could observe increased sphere and colony formation under hypoxic conditions. Mechanistically, microRNA (miRNA)-profiling experiments allowed us to identify miR-215 as one of the main hypoxia-induced miRNAs in primary colon TICs. Through stable overexpression of miR-215, followed by a set of functional in vitro and in vivo investigations, miR-215 was pinpointed as a negative feedback regulator, working against the TIC-promoting effects of hypoxia. Furthermore, we could single out LGR5, a bona fide marker of non-neoplastic intestinal stem cells, as a downstream target of hypoxia/miR-215 signaling. The strong tumor- and TIC-suppressor potential of miR-215 and the regulatory role of the hypoxia/miR-215/LGR5 axis may thus represent interesting points of attack for the development of innovative anti-CSC therapy approaches.

Murine trophoblast-derived and pregnancy-associated exosome-enriched extracellular vesicle microRNAs: Implications for placenta driven effects on maternal physiology

The role of extracellular vesicles (EVs), specifically exosomes, in intercellular communication likely plays a key role in placental orchestration of pregnancy and maternal immune sensing of the fetus. While murine models are powerful tools to study pregnancy and maternal-fetal immune interactions, in contrast to human placental exosomes, the content of murine placental and pregnancy exosomes remains largely understudied. Using a recently developed in vitro culture technique, murine trophoblast stem cells derived from B6 mice were differentiated into syncytial-like cells. EVs from the conditioned media, as well as from pregnant and non-pregnant sera, were enriched for exosomes. The RNA composition of these murine trophoblast-derived and pregnancy-associated exosome-enriched-EVs (ExoE-EVs) was determined using RNA-sequencing analysis and expression levels confirmed by qRT-PCR. Differentially abundant miRNAs were detected in syncytial differentiated ExoE-EVs, particularly from the X chromosome cluster (mmu-miR-322-3p, mmu-miR-322-5p, mmu-miR-503-5p, mmu-miR-542-3p, and mmu-miR-450a-5p). These were confirmed to be increased in pregnant mouse sera ExoE-EVs by qRT-PCR analysis. Interestingly, fifteen miRNAs were only present within the pregnancy-derived ExoE-EVs compared to non-pregnant controls. Mmu-miR-292-3p and mmu-miR-183-5p were noted to be some of the most abundant miRNAs in syncytial ExoE-EVs and were also present at higher levels in pregnant versus non-pregnant sera ExoE-EVs. The bioinformatics tool, MultiMir, was employed to query publicly available databases of predicted miRNA-target interactions. This analysis reveals that the X-chromosome miRNAs are predicted to target ubiquitin-mediated proteolysis and intracellular signaling pathways. Knowing the cargo of placental and pregnancy-specific ExoE-EVs as well as the predicted biological targets informs studies using murine models to examine not only maternal-fetal immune interactions but also the physiologic consequences of placental-maternal communication.

Micrornas at the Interface between Osteogenesis and Angiogenesis as Targets for Bone Regeneration

Bone formation and regeneration is a multistep complex process crucially determined by the formation of blood vessels in the growth plate region. This is preceded by the expression of growth factors, notably the vascular endothelial growth factor (VEGF), secreted by osteogenic cells, as well as the corresponding response of endothelial cells, although the exact mechanisms remain to be clarified. Thereby, coordinated coupling between osteogenesis and angiogenesis is initiated and sustained. The precise interplay of these two fundamental processes is crucial during times of rapid bone growth or fracture repair in adults. Deviations in this balance might lead to pathologic conditions such as osteoarthritis and ectopic bone formation. Besides VEGF, the recently discovered important regulatory and modifying functions of microRNAs also support this key mechanism. These comprise two principal categories of microRNAs that were identified with specific functions in bone formation (osteomiRs) and/or angiogenesis (angiomiRs). However, as hypoxia is a major driving force behind bone angiogenesis, a third group involved in this process is represented by hypoxia-inducible microRNAs (hypoxamiRs). This review was focused on the identification of microRNAs that were found to have an active role in osteogenesis as well as angiogenesis to date that were termed "CouplingmiRs (CPLGmiRs)". Outlined representatives therefore represent microRNAs that already have been associated with an active role in osteogenic-angiogenic coupling or are presumed to have its potential. Elucidation of the molecular mechanisms governing bone angiogenesis are of great relevance for improving therapeutic options in bone regeneration, tissue-engineering, and the treatment of bone-related diseases.

Reciprocal regulations between miRNAs and HIF-1α in human cancers

Hypoxia inducible factor-1α (HIF-1α) is a central molecule involved in mediating cellular processes. Alterations of HIF-1α and hypoxically regulated microRNAs (miRNAs) are correlated with patients' outcome in various cancers, indicating their crucial roles on cancer development. Recently, an increasing number of studies have revealed the intricate regulations between miRNAs and HIF-1α in modulating a wide variety of processes, including proliferation, metastasis, apoptosis, and drug resistance, etc. miRNAs are a class of small noncoding RNAs which function as negative regulators by directly targeting mRNAs. Evidence shows that miRNAs can be regulated by HIF-1α at transcriptional level. In turn, HIF-1α itself can be modulated by many miRNAs whose alterations have been implicated in tumorigenesis, thus forming a reciprocal regulation network. These findings add a new layer of complexity to our understanding of HIF-1α regulatory networks. Here, we will provide a comprehensive overview of the current advances about the bidirectional interactions between HIF-1α and miRNAs in human cancers. Besides, the review will summarize the roles of miRNAs/HIF-1α crosstalk according to various cellular processes. Finally, the potential values of miRNAs/HIF-1α loops in clinical applications are discussed.

Modification of Cardiac Progenitor Cell-Derived Exosomes by miR-322 Provides Protection against Myocardial Infarction through Nox2-Dependent Angiogenesis

Myocardial infarction (MI) is the primary cause of cardiovascular mortality, and therapeutic strategies to prevent or mitigate the consequences of MI are a high priority. Cardiac progenitor cells (CPCs) have been used to treat cardiac injury post-MI, and despite poor engraftment, they have been shown to inhibit apoptosis and to promote angiogenesis through poorly understood paracrine effects. We previously reported that the direct injection of exosomes derived from CPCs (CPCexo) into mouse hearts provides protection against apoptosis in a model of acute ischemia/reperfusion injury. Moreover, we and others have reported that reactive oxygen species (ROS) derived from NADPH oxidase (NOX) can enhance angiogenesis in endothelial cells (ECs). Here we examined whether bioengineered CPCexo transfected with a pro-angiogenic miR-322 (CPCexo-322) can improve therapeutic efficacy in a mouse model of MI as compared to CPCexo. Systemic administration of CPCexo-322 in mice after ischemic injury provided greater protection post-MI than control CPCexo, in part, through enhanced angiogenesis in the border zones of infarcted hearts. Mechanistically, the treatment of cultured human ECs with CPCexo-322 resulted in a greater angiogenic response, as determined by increased EC migration and capillary tube formation via increased Nox2-derived ROS. Our study reveals that the engineering of CPCexo via microRNA (miR) programing can enhance angiogenesis, and this may be an effective therapeutic strategy for the treatment of ischemic cardiovascular diseases.

MicroRNAs in endothelial cell homeostasis and vascular disease

PURPOSE OF REVIEW

Since the first discovery of microRNAs (miRNAs) in 1993, the involvement of miRNAs in different aspects of vascular disease has emerged as an important research field. In this review, we summarize the fundamental roles of miRNAs in controlling endothelial cell functions and their implication with several aspects of vascular dysfunction.

RECENT FINDINGS

MiRNAs have been found to be critical modulators of endothelial homeostasis. The dysregulation of miRNAs has been linked to endothelial dysfunction and the development and progression of vascular disease which and open new opportunities of using miRNAs as potential therapeutic targets for vascular disease.

SUMMARY

Further determination of miRNA regulatory circuits and defining miRNAs-specific target genes remains key to future miRNA-based therapeutic applications toward vascular disease prevention. Many new and unanticipated roles of miRNAs in the control of endothelial functions will assist clinicians and researchers in developing potential therapeutic applications.

Delayed Remote Ischemic Preconditioning ConfersRenoprotection against Septic Acute Kidney Injury via Exosomal miR-21

Sepsis is a common and life-threatening systemic disorder, often leading to acute injury of multiple organs. Here, we show that remote ischemic preconditioning (rIPC), elicited by brief episodes of ischemia and reperfusion in femoral arteries, provides protective effects against sepsis-induced acute kidney injury (AKI).

Methods: Limb rIPC was conducted on mice in vivo 24 h before the onset of cecal ligation and puncture (CLP), and serum exosomes derived from rIPC mice were infused into CLP-challenged recipients. In vitro, we extracted and identified exosomes from differentiated C2C12 cells (myotubes) subjected to hypoxia and reoxygenation (H/R) preconditioning, and the exosomes were administered to lipopolysaccharide (LPS)-treated mouse tubular epithelial cells (mTECs) or intravenously injected into CLP-challenged miR-21 knockout mice for rescue experiments.

Results: Limb rIPC protected polymicrobial septic mice from multiple organ dysfunction, systemic accumulation of inflammatory cytokines and accelerated parenchymal cell apoptosis through upregulation of miR-21 in a hypoxia-inducible factor 1α (HIF-1α)-dependent manner in the ischemic limbs of mice. However, in miR-21 knockout mice or mice that received HIF-1α siRNA injection into hind limb muscles, the organ protection conferred by limb rIPC was abolished. Mechanistically, we discovered that miR-21 was transported from preischemic limbs to remote organs via serum exosomes. In kidneys, the enhanced exosomal miR-21 derived from cultured myotubes with H/R or the serum of mice treated with rIPC integrated into renal tubular epithelial cells and then targeted the downstream PDCD4/NF-κB and PTEN/AKT pathways, exerting anti-inflammatory and anti-apoptotic effects and consequently attenuating sepsis-induced renal injury both in vivo and in vitro.

Conclusion: This study demonstrates a critical role for exosomal miR-21 in renoprotection conferred by limb rIPC against sepsis and suggests that rIPC and exosomes might serve as the possible therapeutic strategies for sepsis-induced kidney injury.

Coregulatory long non-coding RNA and protein-coding genes in serum starved cells

Serum starvation is widely used in cell biology to trigger cell cycle arrest, apoptosis, autophagy, and metabolic adaptations. Serum starvation-related molecular events have been well characterized at protein level but not at transcript level: how long non-coding RNAs contribute to the regulation of protein-coding genes is largely unknown. Here, we captured the lncRNA transcriptome in serum starved mouse embryonic fibroblasts and identified three main modes of action: cis-acting/coregulatory, trans-acting, and "miRNA-carrier". Whole-genome and individual gene level analyses support that our annotation provides an important platform for understanding lncRNA/protein-coding gene coregulatory mechanisms in serum starvation.

The regulatory role of microRNAs in angiogenesis-related diseases

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at a post-transcriptional level via either the degradation or translational repression of a target mRNA. They play an irreplaceable role in angiogenesis by regulating the proliferation, differentiation, apoptosis, migration and tube formation of angiogenesis-related cells, which are indispensable for multitudinous physiological and pathological processes, especially for the occurrence and development of vascular diseases. Imbalance between the regulation of miRNAs and angiogenesis may cause many diseases such as cancer, cardiovascular disease, aneurysm, Kawasaki disease, aortic dissection, phlebothrombosis and diabetic microvascular complication. Therefore, it is important to explore the essential role of miRNAs in angiogenesis, which might help to uncover new and effective therapeutic strategies for vascular diseases. This review focuses on the interactions between miRNAs and angiogenesis, and miRNA-based biomarkers in the diagnosis, treatment and prognosis of angiogenesis-related diseases, providing an update on the understanding of the clinical value of miRNAs in targeting angiogenesis.

Pro- and antiangiogenic therapies: current status and clinical implications

Blood vessels nurture every part of the human body. Consequently, abnormalities in the vasculature are closely associated with a variety of diseases, including cerebral stroke, heart disease, retinopathy, and cancer. Pro- or antiangiogenic therapies can influence these diseases by regulating the growth of new blood vessels from a pre-existing vascular network or dampening excessive blood growth. However, clinical translation of these approaches is slow and challenging. In this review, we discuss recent preclinical approaches to regulate angiogenesis and their potential and risks in a clinical setting.-Rust, R., Gantner, C., Schwab, M. E. Pro- and antiangiogenic therapies: current status and clinical implications.

A HIF-LIMD1 negative feedback mechanism mitigates the pro-tumorigenic effects of hypoxia

The adaptive cellular response to low oxygen tensions is mediated by the hypoxia-inducible factors (HIFs), a family of heterodimeric transcription factors composed of HIF-α and HIF-β subunits. Prolonged HIF expression is a key contributor to cellular transformation, tumorigenesis and metastasis. As such, HIF degradation under hypoxic conditions is an essential homeostatic and tumour-suppressive mechanism. LIMD1 complexes with PHD2 and VHL in physiological oxygen levels (normoxia) to facilitate proteasomal degradation of the HIF-α subunit. Here, we identify LIMD1 as a HIF-1 target gene, which mediates a previously uncharacterised, negative regulatory feedback mechanism for hypoxic HIF-α degradation by modulating PHD2-LIMD1-VHL complex formation. Hypoxic induction of LIMD1 expression results in increased HIF-α protein degradation, inhibiting HIF-1 target gene expression, tumour growth and vascularisation. Furthermore, we report that copy number variation at the LIMD1 locus occurs in 47.1% of lung adenocarcinoma patients, correlates with enhanced expression of a HIF target gene signature and is a negative prognostic indicator. Taken together, our data open a new field of research into the aetiology, diagnosis and prognosis of LIMD1-negative lung cancers.

miR-424 promotes cardiac ischemia/reperfusion injury by direct targeting of CRISPLD2 and regulating cardiomyocyte pyroptosis

As a complex pathophysiological event, myocardial ischemia/reperfusion injury (IRI) can cause heart failure, which has been associated with pyroptosis, a pro-inflammatory programmed cell death. Small endogenous non-coding RNAs have been shown to be involved in myocardial IRI. In the present study, we aimed to investigate whether miR-424 modulated pyroptosis in response to myocardial IRI and determine its underlying regulatory mechanism. An in vivo mouse model of cardiac IRI was established, and contractile function was evaluated by echography. The serum and heart tissue were harvested 24 h after reperfusion to assess the status of pyroptosis. For the in vitro study, H9C2 cells (a rat heart cell line) were subjected to 6 h of hypoxia, followed by 18 h of reoxygenation. The gene expressions at the mRNA level were assessed by real-time PCR, and the expressions at the protein level were examined by western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assay (ELISA). Bioinformatic analysis was applied to predict miR-424 targets, which were then confirmed by a luciferase reporter assay. We found that the expressions of pyroptosis-related proteins, including caspase-1, caspase-11, IL-1β, and IL-18, were significantly increased upon myocardial IRI. Similarly, hypoxia/reoxygenation injury (HRI) also induced pyroptosis in H9C2 cells. Furthermore, our study revealed that the miR-424 expression was substantially increased in I/R heart tissue and H/R-challenged H9C2 cells. In addition, we found that exogenous expression of miR-424 directly targeted cysteine-rich secretory protein LCCL domain-containing 2 (CRISPLD2) and up-regulated the expressions of caspase-1 and the pro-inflammatory cytokines IL-1β and IL-18. Taken together, our findings provided a new signaling pathway of miR-424/CRISPLD2 in cardiac pyroptosis under IRI conditions.

Cancer: the dark side of wound healing

Complex multicellular organisms have evolved sophisticated mechanisms to rapidly resolve epithelial injuries. Epithelial integrity is critical to maintaining internal homeostasis. An epithelial breach represents the potential for pathogen ingress and fluid loss, both of which may have severe consequences if not limited. The mammalian wound healing response involves a finely tuned, self-limiting series of cellular and molecular events orchestrated by the transient activation of specific signalling pathways. Accurate regulation of these events is essential; failure to initiate key steps at the right time delays healing and leads to chronic wounds, while aberrant initiation of wound healing processes may produce cell behaviours that promote cancer progression. In this review, we discuss how wound healing pathways co-opted in cancer lose their stringent regulation and become compromised in their reversibility. We hypothesize on how the commandeering of wound healing 'master regulators' is involved in this process, and also highlight the implications of these findings in the treatment of both chronic wounds and cancer.

The relationship of plasma miR-503 and coronary collateral circulation in patients with coronary artery disease

OBJECTIVE

Although angiogenesis plays an important role in coronary collateral circulation (CCC) formation and there are many determinants of coronary angiogenesis, they cannot fully explain the mechanism of CCC formation or as potent biomarker for CCC status. Therefore, there is of great clinical significance to identify the novel molecules associated with CCC. Previously, miR-503 exerts anti-angiogenesis effect via inhibition of VEGF-A and its expression is associated with many angiogenesis-related factors. Thus, we aimed to investigate the relationship of plasma miR-503 with CCC formation as well as its predictive power for CCC status in patients with coronary artery disease.

METHODS

Among patients who underwent coronary angiography with coronary artery disease and a stenosis of ≥90% were included in our study. Collateral degree was graded according to Rentrop Cohen classification. The patients were divided to good CCC group (grade 2 or 3) and poor CCC group (grade 0 or 1) according to Rentrop grade. We investigated the plasma levels of miR-503 and VEGF-A by ELISA or q RT-PCR, respectively. In addition, we assayed the correlations of plasma miR-503 with VEGF-A or Rentrop grade using the spearman correlation test and its predictive power by receiver operating characteristic (ROC) and binary logistical regression analysis.

RESULTS

Our data showed that plasma VEGF-A was significantly higher in good CCC group than that in poor group. Plasma miR-503 was lower in CAD patients with good CCC or poor CCC compared with control subjects and lowest in good CCC group. In addition, miR-503 negatively correlated with VEGF-A and Rentrop grade, respectively. Moreover, miR-503 displayed more potent predictive power for CCC status than VEGF-A, but its sensitivity and specificity for CCC status were only 72.4 or 60.9%, respectively.

CONCLUSIONS

Lower plasma miR-503 level was related to better CCC formation, accompanied by up-regulation of VEGF-A. In addition, miR-503 displayed potent predictive power for CCC status, but its sensitivity and specificity were not high enough, indicating that miR-503 might be as an additional prognosis biomarker for CCC.

Mesenchymal stem cells release exosomes that transfer miRNAs to endothelial cells and promote angiogenesis

Mesenchymal stem cells (MSCs) have been found to benefit patients with a variety of ischemic diseases via promoting angiogenesis. It is also well established that exosomes secreted from MSCs deliver bioactive molecules, including microRNAs (miRs) to recipient cells. Therefore, we hypothesized that exosomes secreted from MSCs deliver miRs into endothelial cells and mediate angiogenesis. The pro-angiogenic stimulatory capacity of exosomes was investigated using tube-like structure formation and spheroid-based sprouting of human umbilical vein endothelial cells (HUVECs), and in vivo Matrigel plug assay. The secretion of pro-angiogenic miRs (pro-angiomiRs) from MSCs into culture medium and transfer of the miRs to HUVECs were confirmed using real-time quantitative PCR. Supplementation of the exosome secretion blocker GW4869 (10 μM) reduced the pro-angiomiRs in the MSC-derived conditioned medium (CdM^MSC). Addition of exosomes isolated from CdM^MSC could directly 1) promote HUVEC tube-like structure formation in vitro; 2) mobilize endothelial cells into Matrigel plug subcutaneously transplanted into mice; and 3) increase blood flow inside Matrigel plug. Fluorescence tracking showed that the exosomes were internalized rapidly by HUVECs causing an upregulated expression of pro-angiomiRs in HUVECs. Loss-and-gain function of the pro-angiomiRs (e.g., miR-30b) in MSCs significantly altered the pro-angiogenic properties of these MSC-derived exosomes, which could be associated with the regulation of their targets in HUVECs. These results suggest that exosomal transfer of pro-angiogenic miRs plays an important role in MSC mediated angiogenesis and stem cell-to-endothelial cell communication.

eNOS expression and NO release during hypoxia is inhibited by miR-200b in human endothelial cells

The nitric oxide (NO) secreted by vascular endothelium is required for the maintenance of cardiovascular homeostasis. Diminished release of NO generated by endothelial NO synthase contributes to endothelial dysfunction. Hypoxia and ischemia reduce endothelial eNOS expression via posttranscriptional mechanisms that result in NOS3 transcript destabilization. Here, we examine whether microRNAs contribute to this mechanism. We followed the kinetics of hypoxia-induced changes in NOS3 mRNA and eNOS protein levels in primary human umbilical vein endothelial cells (HUVECs). Utilizing in silico predictive protocols to identify potential miRNAs that regulate eNOS expression, we identified miR-200b as a candidate. We established the functional miR-200b target sequence within the NOS3 3′UTR, and demonstrated that manipulation of the miRNA levels during hypoxia using miR-200b mimics and antagomirs regulates eNOS levels, and established that miR-200b physiologically limits eNOS expression during hypoxia. Furthermore, we demonstrated that the specific ablation of the hypoxic induction of miR-200b in HUVECs restored eNOS-driven hypoxic NO release to the normoxic levels. To determine whether miR-200b might be the only miRNA that had this effect, we utilized Next Generation Sequencing (NGS) to follow hypoxia-induced changes in the miRNA levels in HUVECS and found 83 novel hypoxamiRs, with two candidate miRNAs besides miR-200b that could potentially influence eNOS levels. Taken together, the data establish miR-200b-eNOS regulation as a first hypoxamiR-based mechanism that limits NO bioavailability during hypoxia in endothelial cells, and show that hypoxamiRs could become useful therapeutic targets for cardiovascular diseases and other hypoxic-related diseases including various types of cancer.

miRNAs regulate the HIF switch during hypoxia: a novel therapeutic target

The decline of oxygen tension in the tissues below the physiological demand leads to the hypoxic adaptive response. This physiological consequence enables cells to recover from this cellular insult. Understanding the cellular pathways that mediate recovery from hypoxia is therefore critical for developing novel therapeutic approaches for cardiovascular diseases and cancer. The master regulators of oxygen homeostasis that control angiogenesis during hypoxia are hypoxia-inducible factors (HIFs). HIF-1 and HIF-2 function as transcriptional regulators and have both unique and overlapping target genes, whereas the role of HIF-3 is less clear. HIF-1 governs the acute adaptation to hypoxia, whereas HIF-2 and HIF-3 expressions begin during chronic hypoxia in human endothelium. When HIF-1 levels decline, HIF-2 and HIF-3 increase. This switch from HIF-1 to HIF-2 and HIF-3 signaling is required in order to adapt the endothelium to prolonged hypoxia. During prolonged hypoxia, the HIF-1 levels and activity are reduced, despite the lack of oxygen-dependent protein degradation. Although numerous protein factors have been proposed to modulate the HIF pathways, their application for HIF-targeted therapy is rather limited. Recently, the miRNAs that endogenously regulate gene expression via the RNA interference (RNAi) pathway have been shown to play critical roles in the hypoxia response pathways. Furthermore, these classes of RNAs provide therapeutic possibilities to selectively target HIFs and thus modulate the HIF switch. Here, we review the significance of the microRNAs on the relationship between the HIFs under both physiological and pathophysiological conditions.

Imaging of angiogenesis of human umbilical vein endothelial cells by uptake of exosomes secreted from hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a typical hyper-vascular tumor, so the understanding the mechanisms of angiogenesis in HCC is very important for its treatment. However, the influence of the exosomes secreted from HCC cells (HCC-exosomes) on angiogenesis remains poorly understood. We herein examined the effects of the exosomes secreted from HepG2 cells (HepG2-exosomes) on the lumen formation of human umbilical vein endothelial cells (HUVECs) by the imaging of angiogenesis. The degree of lumen formation of HUVECs was dependent on the number of HepG2-exosomes. The HepG2-exosomes expressed NKG2D, an activating receptor for immune cells, and HSP70, a stress-induced heat shock protein associated with angiogenesis through the vascular endothelial growth factor (VEGF) receptor. In addition, the HepG2-exosomes contained several microRNAs (miRNAs) reported to exist in the serum of HCC patients. These results suggest that the HCC-exosomes play an important role in angiogenesis. Further studies on the function of HCC-exosomes may provide a new target for HCC treatment.

Development and validation of a plasma-based melanoma biomarker suitable for clinical use

This corrects the article DOI: 10.1038/bjc.2017.85.

Non-coding RNA regulation of endothelial and macrophage functions during atherosclerosis

The endothelial lining can be viewed as the first line of defense against risk factors of vascular disease. Endothelial dysfunction is regarded as an initial event for atherogenesis since defects in vascular integrity and homeostasis are responsible for lipid infiltration and recruitment of monocytes into the vessel wall. Monocytes-turned-macrophages, which possess astounding inflammatory plasticity, perpetuate chronic inflammation and growth of atherosclerotic plaques and, are therefore central for the pathogenesis of atherosclerosis. Because endothelial cells and macrophages are key players during atherogenesis, it is crucial to understand the regulation of their functions in order to develop strategies to intervene disease progression. Interestingly, non-coding RNAs (ncRNAs), broad class of RNA molecules that do not code for proteins, are capable of reprogramming multiple cell functions and, thus, can be used as target agents. MicroRNAs are small ncRNAs whose roles in the regulation of vascular functions and development of atherosclerosis through post-transcriptional manipulation of gene expression have been widely explored. Recently, other ncRNAs including long noncoding RNAs (lncRNAs) have also emerged as potential regulators of these functions. However, given their poor-genetic conservation between species, much work will be needed to elucidate the specific role of lncRNAs in vascular biology. This review aims to provide a comprehensive perspective of ncRNA, mostly focusing in lncRNAs, mechanism of action and relevance in regulating lipid metabolism-independent endothelial and macrophages functions in the pathogenesis of atherosclerosis.

PDGFR-alpha inhibits melanoma growth via CXCL10/IP-10: a multi-omics approach

Melanoma is the most aggressive skin-cancer, showing high mortality at advanced stages. Platelet Derived Growth Factor Receptor-alpha (PDGFR-alpha) potently inhibits melanoma- and endothelium-proliferation and its expression is significantly reduced in melanoma-biopsies, suggesting that melanoma progression eliminates cells expressing PDGFR-alpha. In the present study transient overexpression of PDGFR-alpha in endothelial (HUVEC) and melanoma (SKMel-28, A375, Preyer) human-cells shows strong anti-proliferative effects, with profound transcriptome and miRNome deregulation. PDGFR-alpha overexpression strongly affects expression of 82 genes in HUVEC (41 up-, 41 down-regulated), and 52 genes in SKMel-28 (43 up-, 9 down-regulated). CXCL10/IP-10 transcript showed up to 20 fold-increase, with similar changes detectable at the protein level. miRNA expression profiling in cells overexpressing PDGFR-alpha identified 14 miRNAs up- and 40 down-regulated, with miR-503 being the most down-regulated (6.4 fold-reduction). miR-503, miR-630 and miR-424 deregulation was confirmed by qRT-PCR. Interestingly, the most upregulated transcript (i.e., CXCL10/IP-10) was a validated miR-503 target and CXCL10/IP-10 neutralization significantly reverted the anti-proliferative action of PDGFR-alpha, and PDGFR-alpha inhibition by Dasatinb totally reverted the CXCL10/IP10 induction, further supporting a functional interplay of these factors. Finally, integration of transcriptomics and miRNomics data highlighted several pathways affected by PDGFR-alpha.

This study demonstrates for the first time that PDGFR-alpha strongly inhibits endothelial and melanoma cells proliferation in a CXCL10/IP-10 dependent way, via miR-503 down-regulation.

Advances in Hypoxia-Inducible Factor Biology

Hypoxia-inducible factor (HIF), a central regulator for detecting and adapting to cellular oxygen levels, transcriptionally activates genes modulating oxygen homeostasis and metabolic activation. Beyond this, HIF influences many other processes. Hypoxia, in part through HIF-dependent mechanisms, influences epigenetic factors, including DNA methylation and histone acetylation, which modulate hypoxia-responsive gene expression in cells. Hypoxia profoundly affects expression of many noncoding RNAs classes that have clinicopathological implications in cancer. HIF can regulate noncoding RNAs production, while, conversely, noncoding RNAs can modulate HIF expression. There is recent evidence for crosstalk between circadian rhythms and hypoxia-induced signaling, suggesting involvement of molecular clocks in adaptation to fluxes in nutrient and oxygen sensing. HIF induces increased production of cellular vesicles facilitating intercellular communication at a distance-for example, promoting angiogenesis in hypoxic tumors. Understanding the complex networks underlying cellular and genomic regulation in response to hypoxia via HIF may identify novel and specific therapeutic targets.

Dissecting microRNA dysregulation in age-related macular degeneration: new targets for eye gene therapy

MicroRNAs (miRNAs) are key regulators of gene expression in humans. Overexpression or depletion of individual miRNAs is associated with human disease. Current knowledge suggests that the retina is influenced by miRNAs and that dysregulation of miRNAs as well as alterations in components of the miRNA biogenesis machinery are involved in retinal diseases, including age-related macular degeneration (AMD). Furthermore, recent studies have indicated that the vitreous has a specific panel of circulating miRNAs and that this panel varies according to the specific pathological stress experienced by the retinal cells. MicroRNA (miRNA) profiling indicates subtype-specific miRNA profiles for late-stage AMD highlighting the importance of proper miRNA regulation in AMD. This review will describe the function of important miRNAs involved in inflammation, oxidative stress and pathological neovascularization, the key molecular mechanisms leading to AMD, and focus on dysregulated miRNAs as potential therapeutic targets in AMD.

miR-322-5p targets IGF-1 and is suppressed in the heart of rats with pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterised by remodelling of the pulmonary vasculature leading to right ventricular hypertrophy. Here, we show that miR‐322‐5p (the rodent orthologue of miR‐424‐5p) expression is decreased in the right ventricle of monocrotaline‐treated rats, a model of PAH, whereas a putative target insulin‐like growth factor 1 (IGF‐1) is increased. IGF‐1 mRNA was enriched 16‐fold in RNA immunoprecipitated with Ago2, indicating binding to miR‐322‐5p. In cell transfection experiments, miR‐322‐5p suppressed the activity of a luciferase reporter containing a section of the IGF‐1 3′ untranslated region (UTR) as well as IGF‐1 mRNA and protein levels. Taken together, these data suggest that miR‐322 targets IGF‐1, a process downregulated in PAH‐related RV hypertrophy.

Hypoxia-induced microRNA-590-5p promotes colorectal cancer progression by modulating matrix metalloproteinase activity

Hypoxia leads to cancer progression and promotes the metastatic potential of cancer cells. MicroRNAs (miRNAs) are small non-coding RNA that have emerged as key players involved in cancer development and progression. Hypoxia alters a set of hypoxia-mediated miRNAs expression during tumor development and it may function as oncogenes or tumor-suppressors. However, the roles and molecular mechanisms of hypoxia-regulatory miRNAs in colorectal cancer (CRC) progression remain poorly understood. Here we firstly identified miR-590-5p as hypoxia-sensitive miRNAs which was upregulated in colon cancer cells under hypoxia. Hypoxia-induced miR-590-5p suppressed the expression of RECK, in turn, promoting cell invasiveness and migratory abilities via activation of matrix metalloproteinases (MMPs) and filopodia protrusion in vitro. Inhibition of miR-590-5p suppressed tumor growth and metastasis in mouse xenograft and CRC liver metastasis models via inhibition of MMPs activity. Clinical analysis revealed higher miR-590-5p expression in CRC, compared to normal specimens. Furthermore, miR-590-5p expression was significantly increased in liver metastasis as compared to their matched primary CRC. Taken together, our findings provide the first evidence that miR-590-5p may have potential as a therapeutic target for CRC patients with metastasis.

Gender and cardiovascular disease: are sex-biased microRNA networks a driving force behind heart failure with preserved ejection fraction in women?

Cardiovascular disease (CVD) is the primary cause of death among men and women worldwide. Nevertheless, our comprehension of how CVD progresses in women and elicits clinical outcomes is lacking, leading CVD to be under-diagnosed and under-treated in women. A clear example of this differential presentation of CVD pathophysiologies in females is the strikingly higher prevalence of heart failure with preserved ejection fraction (HFpEF). Women with a history of pre-eclampsia or those who present with co-morbidities such as obesity, hypertension, and diabetes mellitus are at increased risk of developing HFpEF. Long understood to be a critical CVD risk factor, our understanding of how gender differentially affects the development of CVD has been greatly expanded by extensive genomic and transcriptomic studies. These studies uncovered a pivotal role for differential microRNA (miRNA) expression in response to systemic inflammation, where their co-ordinated expression forms a post-transcriptional regulatory network that instigates microcirculation defects. Importantly, the potential sex-biased expression of the given miRNAs may explain sex-specific cardiovascular pathophysiologies in women, such as HFpEF. Sex-biased miRNAs are regulated by oestrogen (E2) in their transcription and processing or are expressed from loci on the X-chromosome due to incomplete X-chromosome inactivation. Interestingly, while E2-induced miRNAs predominantly appear to serve protective functions, it could be argued that many X-linked miRNAs have been found to challenge microvascular and myocardial integrity. Therefore, menopausal E2 deficiency, resulting in protective miRNA loss, and the augmentation of X-linked miRNA expression, may well contribute to the molecular mechanisms that underlie the female-specific cardiovascular aetiology in HFpEF.

miRNome Profiling in Bicuspid Aortic Valve-Associated Aortopathy by Next-Generation Sequencing

The molecular mechanisms underlying thoracic aortic aneurysm (TAA) in patients with bicuspid aortic valve (BAV) are incompletely characterized. MicroRNAs (miRNAs) may play a major role in the different pathogenesis of aortopathy. We sought to employ next-generation sequencing to analyze the entire miRNome in TAA tissue from patients with BAV and tricuspid aortic valve (TAV). In the discovery stage, small RNA sequencing was performed using the Illumina MiSeq platform in 13 TAA tissue samples (seven patients with BAV and six with TAV). Gene ontology (GO) and KEGG pathway analysis were used to identify key pathways and biological functions. Validation analysis was performed by qRT-PCR in an independent cohort of 30 patients with BAV (26 males; 59.5 ± 12 years) and 30 patients with TAV (16 males; 68.5 ± 9.5 years). Bioinformatic analysis identified a total of 489 known mature miRNAs and five novel miRNAs. Compared to TAV samples, 12 known miRNAs were found to be differentially expressed in BAV, including two up-regulated and 10 down-regulated (FDR-adjusted p-value ≤ 0.05 and fold change ≥  1.5). GO and KEGG pathway enrichment analysis (FDR-adjusted p-value < 0.05) identified different target genes and pathways linked to BAV and aneurysm formation, including Hippo signaling pathway, ErbB signaling, TGF-beta signaling and focal adhesion. Validation analysis of selected miRNAs confirmed the significant down-regulation of miR-424-3p (p = 0.01) and miR-3688-3p (p = 0.03) in BAV patients as compared to TAV patients. Our study provided the first in-depth screening of the whole miRNome in TAA specimens and identified specific dysregulated miRNAs in BAV patients.

Comparative analysis of the microRNA transcriptome between yak and cattle provides insight into high-altitude adaptation

Extensive and in-depth investigations of high-altitude adaptation have been carried out at the level of morphology, anatomy, physiology and genomics, but few investigations focused on the roles of microRNA (miRNA) in high-altitude adaptation. We examined the differences in the miRNA transcriptomes of two representative hypoxia-sensitive tissues (heart and lung) between yak and cattle, two closely related species that live in high and low altitudes, respectively. In this study, we identified a total of 808 mature miRNAs, which corresponded to 715 pre-miRNAs in the two species. The further analysis revealed that both tissues showed relatively high correlation coefficient between yak and cattle, but a greater differentiation was present in lung than heart between the two species. In addition, miRNAs with significantly differentiated patterns of expression in two tissues exhibited co-operation effect in high altitude adaptation based on miRNA family and cluster. Functional analysis revealed that differentially expressed miRNAs were enriched in hypoxia-related pathways, such as the HIF-1α signaling pathway, the insulin signaling pathway, the PI3K-Akt signaling pathway, nucleotide excision repair, cell cycle, apoptosis and fatty acid metabolism, which indicated the important roles of miRNAs in high altitude adaptation. These results suggested the diverse degrees of miRNA transcriptome variation in different tissues between yak and cattle, and suggested extensive roles of miRNAs in high altitude adaptation.

IL-13 enhances mesenchymal transition of pulmonary artery endothelial cells via down-regulation of miR-424/503 in vitro

Pulmonary arterial hypertension (PAH) has a major effect on life expectancy with functional degeneracy of the lungs and right heart. Interleukin-13 (IL-13), one of the type 2 cytokines mainly associated with allergic diseases, has recently been reported to be associated with Schistosomiasis-associated PAH which shares pathological features with other forms of PAH, such as idiopathic PAH and connective tissue disease-associated PAH. But a direct pathological role of IL-13 in the development of PAH has not been explored. We examined the effects of recombinant human IL-13 on the function of primary human pulmonary artery endothelial cells (HPAECs) to examine how IL-13 influences exacerbation of PAH. IL-13 increased the expression of Rictor, which is a key molecule of mammalian target of rapamycin complex 2. Treatment of IL-13 induced HPAEC migration via Rictor. Rictor was directly regulated by both miR-424 and 503 (miR-424/503). Therefore, IL-13 increases Rictor level by regulating miR-424/503, causing the increase of HPAEC migration. Since enhancement of HPAEC migration in the lung is thought to be associated with PAH, these data suggest that IL-13 takes some roles in exacerbating PAH.

The expression and function of miR-424 in infantile skin hemangioma and its mechanism

Infantile hemangioma is the most common benign tumor in infants. Many studies have confirmed that basic fibroblast growth factor (bFGF) and its key receptor FGFR1 are highly expressed in hemangioma. Moreover, several miRNAs can regulate angiogenesis. In this regard, miR-424 often plays a role as tumor suppressor gene. This study was designed to investigate the mechanism of miR-424 in infantile skin hemangioma. Our results showed low expression of miR-424 in infantile skin hemangioma tissues, and that miR-424 overexpression downregulated FGFR1 expression in hemangioma-derived endothelial cells, while miR-424 inhibition upregulated FGFR1 expression. Luciferase reporter analysis confirmed that FGFR1 was a target gene of miR-424. CCK-8, flow cytometry, transwell migration and tube formation assays demonstrated that miR-424 overexpression inhibited cell proliferation, migration and tube formation, at least in part by blocking the bFGF/FGFR1 pathway. In contrast, miR-424 inhibition significantly enhanced these functions. Furthermore, miR-424 overexpression significantly inhibited ERK1/2 phosphorylation, whereas miR-424 inhibition enhanced ERK1/2 phosphorylation. In conclusion, miR-424 could suppress the bFGF/FGFR1 pathway, thereby inhibit ERK1/2 phosphorylation, and thus inhibit cell proliferation, migration and tube formation capabilities and the development of infantile skin hemangioma.

Tumor microenvironment and noncoding RNAs as co-drivers of epithelial-mesenchymal transition and cancer metastasis

Reciprocal interactions between cancer cells and tumor microenvironment (TME) are crucial events in tumor progression and metastasis. Pervasive stromal reprogramming of TME modifies numerous cellular functions, including extracellular matrix (ECM) stiffness, inflammation, and immunity. These environmental factors allow selection of more aggressive cells that develop adaptive strategies associating plasticity and epithelial-mesenchymal transition (EMT), stem-like phenotype, invasion, immunosuppression, and resistance to therapies. EMT is a morphomolecular process that endows epithelial tumor cells with mesenchymal properties, including reduced adhesion and increased motility. Numerous studies have demonstrated involvement of noncoding RNAs (ncRNAs), such as miRNAs and lncRNAs, in tumor initiation, progression, and metastasis. NcRNAs regulate every hallmark of cancer and have now emerged as new players in induction and regulation of EMT. The reciprocal regulatory interactions between ncRNAs, TME components, and cancer cells increase the complexity of gene expression and protein translation in cancer. Thus, deeper understanding of molecular mechanisms controlling EMT will not only shed light on metastatic processes of cancer cells, but enhance development of new therapies targeting metastasis. In this review, we will provide recent findings on the role of known ncRNAs relevant to EMT and cancer metastasis and discuss the role of the interaction between ncRNAs and TME as co-drivers of EMT. Developmental Dynamics 247:405-431, 2018. © 2017 Wiley Periodicals, Inc.

A microfluidic oxygen gradient demonstrates differential activation of the hypoxia-regulated transcription factors HIF-1α and HIF-2α

Gas-perfused microchannels generated a linear oxygen gradient via diffusion across a 100 μm polydimethylsiloxane (PDMS) membrane. The device enabled exposure of a single monolayer of cells sharing culture media to a heterogeneous oxygen landscape, thus reflecting the oxygen gradients found at the microscale in the physiological setting and allowing for the real-time exchange of paracrine factors and metabolites between cells exposed to varying oxygen levels. By tuning the distance between two gas supply channels, the slope of the oxygen gradient was controlled. We studied the hypoxic activation of the transcription factors HIF-1α and HIF-2α in human endothelial cells within a spatial linear gradient of oxygen. Quantification of the nuclear to cytosolic ratio of HIF immunofluorescent staining demonstrated that the threshold for HIF-1α activation was below 2.5% O2 while HIF-2α was activated throughout the entire linear gradient. We show for the first time HIF-2α is subject to hyproxya, hypoxia by proxy, wherein hypoxic cells activate HIF in close-proximity normoxic cells. These results underscore the differences between HIF-1α and HIF-2α regulation and suggest that a microfluidic oxygen gradient is a novel tool for identifying distinct hypoxic signaling activation and interactions between differentially oxygenated cells.

Changes in CD73, CD39 and CD26 expression on T-lymphocytes of ANCA-associated vasculitis patients suggest impairment in adenosine generation and turn-over

Extracellular adenosine, generated via the concerted action of CD39 and CD73, contributes to T-cell differentiation and function. Adenosine concentrations are furthermore influenced by adenosine deaminase binding protein CD26. Because aberrant T-cell phenotypes had been reported in anti-neutrophil cytoplasmic auto-antibody (ANCA)-associated vasculitis (AAV) patients, an impaired expression of these molecules on T-cells of AAV patients was hypothesized in the present study. While in AAV patients (n = 29) CD26 was increased on CD4⁺ lymphocytes, CD39 and CD73 were generally reduced on patients’ T-cells. In CD4⁺ cells significant differences in CD73 expression were confined to memory CD45RA^- cells, while in CD4^- lymphocytes differences were significant in both naïve CD45RA⁺ and memory CD45RA^- cells. The percentage of CD4^-CD73⁺ cells correlated with micro-RNA (miR)−31 expression, a putative regulator of factor inhibiting hypoxia-inducible factor 1 alpha (FIH-1), inversely with serum C-reactive protein (CRP) and positively with estimated glomerular filtration rate (eGFR). No correlation with disease activity, duration, and ANCA profile was found. It remains to be assessed if a decreased CD73 and CD39 expression underlies functional impairment of lymphocytes in AAV patients. Likewise, the relations between frequencies of CD4^-CD73⁺ cells and serum CRP or eGFR require further functional elucidation.

Whole blood microRNA markers are associated with acute respiratory distress syndrome

BACKGROUND

MicroRNAs (miRNAs) can play important roles in inflammation and infection, which are common manifestations of acute respiratory distress syndrome (ARDS). We assessed if whole blood miRNAs were potential diagnostic biomarkers for human ARDS.

METHODS

This nested case-control study (N = 530) examined a cohort of ARDS patients and critically ill at-risk controls. Whole blood miRNA profiles and logistic regression analyses identified miRNAs correlated with ARDS. Stratification analysis also assessed selected miRNA markers for their role in sepsis and pneumonia associated with ARDS. Receiver operating characteristic (ROC) analysis evaluated miRNA diagnostic performance, along with Lung Injury Prediction Score (LIPS).

RESULTS

Statistical analyses were performed on 294 miRNAs, selected from 754 miRNAs after quality control screening. Logistic regression identified 22 miRNAs from a 156-patient discovery cohort as potential risk or protective markers of ARDS. Three miRNAs-miR-181a, miR-92a, and miR-424-from the discovery cohort remained significantly associated with ARDS in a 373-patient independent validation cohort (FDR q < 0.05) and meta-analysis (p < 0.001). ROC analyses demonstrated a LIPS baseline area-under-the-curve (AUC) value of ARDS of 0.708 (95% CI 0.651-0.766). Addition of miR-181a, miR-92a, and miR-424 to LIPS increased baseline AUC to 0.723 (95% CI 0.667-0.778), with a relative integrated discrimination improvement of 2.40 (p = 0.005) and a category-free net reclassification index of 27.21% (p = 0.01).

CONCLUSIONS

miR-181a and miR-92a are risk biomarkers for ARDS, whereas miR-424 is a protective biomarker. Addition of these miRNAs to LIPS can improve the risk estimate for ARDS.

Integrative miRNA and mRNA analysis in penile carcinomas reveals markers and pathways with potential clinical impact

Penile carcinoma (PeCa) is an important public health issue in poor and developing countries, and has only recently been explored in terms of genetic and epigenetic studies. Integrative data analysis is a powerful method for the identification of molecular drivers involved in cancer development and progression. miRNA and mRNA expression profiles followed by integrative analysis were investigated in 23 PeCa and 12 non-neoplastic penile tissues (NPT). Expression levels of eight miRNAs and 10 mRNAs were evaluated in the same set of samples used for microarray and in a validation set of cases (PeCa = 36; NPT = 27). Eighty-one miRNAs and 2,697 mRNAs were identified as differentially expressed in PeCa. Integrative data analysis revealed 255 mRNAs potentially regulated by 68 miRNAs. Using RT-qPCR, eight miRNAs and nine transcripts were confirmed as altered in PeCa. We identified that MMP1, MMP12 and PPARG and hsa-miR-31-5p, hsa-miR-224-5p, and hsa-miR-223-3p were able to distinguish tumors from NPT with high sensitivity and specificity. Higher MMP1 expression was detected as a better predictor of lymph node metastasis than the clinical-pathological data. In addition, PPARG and EGFR were highlighted as potential pathways for targeted therapy in PeCa. The analysis based on HPV positivity (7 of 23 cases) revealed five miRNA and 13 mRNA differentially expressed. Although in a limited number of cases, HPV positive PeCa presented less aggressive phenotype in comparison with negative cases. Overall, an integrative analysis using mRNA and miRNA profiles revealed markers related with tumor development and progression. Furthermore, MMP1 expression level was a predictive marker for lymph node metastasis in patients with PeCa.

Downregulation of microRNA-195 promotes angiogenesis induced by cerebral infarction via targeting VEGFA

Angiogenesis, the formation of new blood vessels from preexisting endothelium, is a process that involves a series of interassociated and mutually interactive pathophysiological processes. It is accepted that microRNAs (miRNAs) regulate endothelial cell behavior, including their involvement in angiogenesis. However, it remains unclear whether miRNAs are involved in the regulation of angiogenesis following cerebral ischemia. Therefore, the present study aimed to investigate the role of miRNAs in angiogenesis and the underlying mechanism following cerebral ischemia. Expression profiles of miRNAs in rat brain samples following middle cerebral artery occlusion (MCAO) were investigated using a miRNA microarray. The expression of candidate miRNA, miR‑195 was further validated using reverse transcription‑quantitative polymerase chain reaction. Then, the effects of miR‑195 on cell migration and tube formation of human umbilical vein vascular endothelial cells (HUVECs) were investigated following miR‑195 silencing, and overexpression. The specific target genes of miR‑195 were predicted using microRNA prediction bioinformatics software (http://www.microrna.org/microrna/home.do), and then confirmed using a dual‑luciferase reporter assay and rescue experiment. It was demonstrated that miR‑195 was significantly downregulated in the brains of rats following MCAO and in hypoxia‑induced HUVECs. Furthermore, it was revealed that miR‑195 overexpression inhibited the invasion ability and tube formation of HUVECs in vitro, while miR‑195 silencing enhanced these functions. In addition, vascular endothelial growth factor A (VEGFA) was identified as a direct target of miR‑195 and was negatively correlated with miR‑195 expression. In addition, the rescue experiment revealed that overexpression of VEGFA reversed the inhibitory effects of miR‑195 overexpression on the invasion ability and tube formation of HUVECs. The present study has provided a novel insight into the promoting roles of miR‑195 downregulation on angiogenesis following cerebral infarction and suggests that the miR‑195/VEGFA signaling pathway is a putative therapeutic target in cerebral ischemia.

Hypoxia in CNS Pathologies: Emerging Role of miRNA-Based Neurotherapeutics and Yoga Based Alternative Therapies

Cellular respiration is a vital process for the existence of life. Any condition that results in deprivation of oxygen (also termed as hypoxia) may eventually lead to deleterious effects on the functioning of tissues. Brain being the highest consumer of oxygen is prone to increased risk of hypoxia-induced neurological insults. This in turn has been associated with many diseases of central nervous system (CNS) such as stroke, Alzheimer's, encephalopathy etc. Although several studies have investigated the pathophysiological mechanisms underlying ischemic/hypoxic CNS diseases, the knowledge about protective therapeutic strategies to ameliorate the affected neuronal cells is meager. This has augmented the need to improve our understanding of the hypoxic and ischemic events occurring in the brain and identify novel and alternate treatment modalities for such insults. MicroRNA (miRNAs), small non-coding RNA molecules, have recently emerged as potential neuroprotective agents as well as targets, under hypoxic conditions. These 18-22 nucleotide long RNA molecules are profusely present in brain and other organs and function as gene regulators by cleaving and silencing the gene expression. In brain, these are known to be involved in neuronal differentiation and plasticity. Therefore, targeting miRNA expression represents a novel therapeutic approach to intercede against hypoxic and ischemic brain injury. In the first part of this review, we will discuss the neurophysiological changes caused as a result of hypoxia, followed by the contribution of hypoxia in the neurodegenerative diseases. Secondly, we will provide recent updates and insights into the roles of miRNA in the regulation of genes in oxygen and glucose deprived brain in association with circadian rhythms and how these can be targeted as neuroprotective agents for CNS injuries. Finally, we will emphasize on alternate breathing or yogic interventions to overcome the hypoxia associated anomalies that could ultimately lead to improvement in cerebral perfusion.

Folate deficiency disturbs hsa-let-7 g level through methylation regulation in neural tube defects

Folic acid deficiency during pregnancy is believed to be a high‐risk factor for neural tube defects (NTDs). Disturbed epigenetic modifications, including miRNA regulation, have been linked to the pathogenesis of NTDs in those with folate deficiency. However, the mechanism by which folic acid‐regulated miRNA influences this pathogenesis remains unclear. It is believed that DNA methylation is associated with dysregulated miRNA expression. To clarify this issue, here we measured the methylation changes of 22 miRNAs in 57 human NTD cases to explore whether such changes are involved in miRNA regulation in NTD cases through folate metabolism. In total, eight of the 22 miRNAs tested reduced their methylation modifications in NTD cases, which provide direct evidence of the roles of interactions between DNA methylation and miRNA level in these defects. Among the findings, there was a significant association between folic acid concentration and hsa‐let‐7 g methylation level in NTD cases. Hypomethylation of hsa‐let‐7 g increased its own expression level in both NTD cases and cell models, which indicated that hsa‐let‐7 g methylation directly regulates its own expression. Overexpression of hsa‐let‐7 g, along with its target genes, disturbed the migration and proliferation of SK‐N‐SH cells, implying that hsa‐let‐7 g plays important roles in the prevention of NTDs by folic acid. In summary, our data suggest a relationship between aberrant methylation of hsa‐let‐7 g and disturbed folate metabolism in NTDs, implying that improvements in nutrition during early pregnancy may prevent such defects, possibly via the donation of methyl groups for miRNAs.