miR-370 inhibits the angiogenic activity of endothelial cells by targeting smoothened (SMO) and bone morphogenetic protein (BMP)-2

The role of long noncoding RNAs in ocular angiogenesis and vascular oculopathy

BACKGROUND

Long noncoding RNAs (lncRNAs) are RNA transcripts over 200 nucleotides in length that do not code for proteins. Initially considered a genomic mystery, an increasing number of lncRNAs have been shown to have vital roles in physiological and pathological conditions by regulating gene expression through diverse mechanisms depending on their subcellular localization. Dysregulated angiogenesis is responsible for various vascular oculopathies, including diabetic retinopathy, retinopathy of prematurity, age-related macular degeneration, and corneal neovascularization. While anti-VEGF treatment is available, it is not curative, and long-term outcomes are suboptimal, and some patients are unresponsive. To better understand these diseases, researchers have investigated the role of lncRNAs in regulating angiogenesis and models of vascular oculopathies. This review summarizes recent research on lncRNAs in ocular angiogenesis, including the pro-angiogenic lncRNAs ANRIL, HOTAIR, HOTTIP, H19, IPW, MALAT1, MIAT, NEAT1, and TUG1, the anti-angiogenic lncRNAs MEG3 and PKNY, and the human/primate specific lncRNAs lncEGFL7OS, discussing their functions and mechanisms of action in vascular oculopathies.

Brassinin Promotes the Degradation of Tie2 and FGFR1 in Endothelial Cells and Inhibits Triple-Negative Breast Cancer Angiogenesis

Simple Summary

Brassinin is a natural compound enriched in several commonly consumed vegetables, such as broccoli and cabbages. It shows potent anti-cancer activity against several cancers. However, its effects on triple-negative breast cancer (TNBC), an aggressive subtype with limited treatment options, remain elusive so far. Therefore, we investigated the effects of brassinin on TNBC angiogenesis and growth. Our results demonstrate that brassinin inhibits TNBC growth preferentially through inhibiting the angiogenic activity of endothelial cells (ECs). Additional in-vitro analyses revealed that this effect may be mediated by brassinin-stimulated degradation of two pivotal angiogenesis-related receptors in ECs: Tie2 and fibroblast growth factor receptor 1. These findings provide novel insights into the cellular and molecular mechanisms underlying the anti-cancer activity of brassinin and indicate that this phytochemical may be a promising lead compound or drug candidate for TNBC treatment.

Abstract

Brassinin, a phytoalexin derived from cruciferous vegetables, has been reported to exhibit anti-cancer activity in multiple cancer types. However, its effects on triple-negative breast cancer (TNBC) development and the underlying mechanisms have not been elucidated so far. In this study, we demonstrated in vitro that brassinin preferentially reduces the viability of endothelial cells (ECs) when compared to other cell types of the tumor microenvironment, including TNBC cells, pericytes, and fibroblasts. Moreover, brassinin at non-cytotoxic doses significantly suppressed the proliferation, migration, tube formation, and spheroid sprouting of ECs. It also efficiently inhibited angiogenesis in an ex-vivo aortic ring assay and an in-vivo Matrigel plug assay. Daily intraperitoneal injection of brassinin significantly reduced tumor size, microvessel density, as well as the perfusion of tumor microvessels in a dorsal skinfold chamber model of TNBC. Mechanistic analyses showed that brassinin selectively stimulates the degradation of Tie2 and fibroblast growth factor receptor 1 in ECs, leading to the down-regulation of the AKT and extracellular signal-regulated kinase pathways. These findings demonstrate a preferential and potent anti-angiogenic activity of brassinin, which may be the main mechanism of its anti-tumor action. Accordingly, this phytochemical represents a promising candidate for the future anti-angiogenic treatment of TNBC.

Long non-coding RNA MEG8 induces endothelial barrier through regulation of microRNA-370 and -494 processing

The 14q32 locus is an imprinted region in the human genome which contains multiple non-coding RNAs. We investigated the role of Maternally Expressed Gene 8 (MEG8) in endothelial function and the underlying mechanism. A 5-fold increase in MEG8 was observed with increased passage number in Human Umbilical Vein Endothelial Cells, suggesting MEG8 is induced during aging. MEG8 knockdown resulted in a 1.8-fold increase in senescence, suggesting MEG8 might be protective during aging. Endothelial barrier was impaired after MEG8 silencing. MEG8 knockdown resulted in reduced expression of miRNA-370 and -494 but not -127, -487b and -410. Overexpression of miRNA-370/-494 partially rescued MEG8-silencing-induced barrier loss. Mechanistically, MEG8 regulates expression of miRNA-370 and -494 at the mature miRNA level through interaction with RNA binding proteins Cold Inducible RNA Binding Protein (CIRBP) and Hydroxyacyl-CoA Dehydrogenase Trifunctional Multi-enzyme Complex Subunit Beta (HADHB). Precursor and mature miRNA-370/-494 were shown to interact with HADHB and CIRBP respectively. CIRBP/HADHB silencing resulted in downregulation of miRNA-370 and induction of miRNA-494. These results suggest MEG8 interacts with CIRBP and HADHB and contributes to miRNA processing at the post-transcriptional level.

Amniotic Fluid microRNA in Severe Twin-Twin Transfusion Syndrome Cardiomyopathy-Identification of Differences and Predicting Demise

Twin-twin transfusion syndrome (TTTS) is a rare but serious cause of fetal cardiomyopathy with poorly understood pathophysiology and challenging prognostication. This study sought a nonbiased, comprehensive assessment of amniotic fluid (AF) microRNAs from TTTS pregnancies and associations of these miRNAs with clinical characteristics. For the discovery cohort, AF from ten fetuses with severe TTTS cardiomyopathy were selected and compared to ten normal singleton AF. Array panels assessing 384 microRNAs were performed on the discovery cohort and controls. Using a stringent q < 0.0025, arrays identified 32 miRNAs with differential expression. Top three microRNAs were miR-99b, miR-370 and miR-375. Forty distinct TTTS subjects were selected for a validation cohort. RT-PCR targeted six differentially-expressed microRNAs in the discovery and validation cohorts. Expression differences by array were confirmed by RT-PCR with high fidelity. The ability of these miRNAs to predict clinical differences, such as cardiac findings and later demise, was evaluated on TTTS subjects. Down-regulation of miRNA-127-3p, miRNA-375-3p and miRNA-886 were associated with demise. Our results indicate AF microRNAs have potential as a diagnostic and prognostic biomarker in TTTS. The top microRNAs have previously demonstrated roles in angiogenesis, cardiomyocyte stress response and hypertrophy. Further studies of the mechanism of actions and potential targets is warranted.

Trimethylamine N-oxide promotes atherosclerosis via regulating the enriched abundant transcript 1/miR-370-3p/signal transducer and activator of transcription 3/flavin-containing monooxygenase-3 axis

Atherosclerosis (AS) is one of the main causes of cardiovascular diseases (CVDs). Trimethylamine N-oxide (TMAO) exacerbates the development of AS. This study aimed to investigate the roles of TMAO in AS. In this study, mice were fed with high fat food (HF) and/or injected with TMAO. Oil red O staining was applied for histological analysis. ELISA, qRT-PCR, and Western blot were conducted to determine the TMAO, serum, mRNA, and protein levels. CCK-8, colony formation assay, and flow cytometry assays were performed to detect the functions of human aortic endothelial cells (HUVECs). The results showed that TMAO induced thick internal and external walls and intimal plaques in vivo, and HUVEC dysfunction in vitro. TMAO and lncRNA enriched abundant transcript 1 (NEAT1) were increased in AS clinical samples and TMAO-HUVECs. Downregulated NEAT1 inhibited proliferation and promoted the apoptosis of HUVECs. NEAT1 regulated the expression of signal transducer and activator of transcription 3 (STAT3) via sponging miR-370-3p. Overexpression of miR-370-3p facilitated the effects of NEAT1 on the cellular functions of HUVECs, while STAT3 exerted opposing effects. The activation of STAT3 promoted the expression of flavin-containing monooxygenase-3 (FMO3). Taken together, our results show that TMAO-NEAT1/miR-370-3p/STAT3/FMO3 forms a positive feedback loop to exacerbate the development of AS. This novel feedback loop may be a promising therapeutic target for AS.

Suppression of endothelial miR-22 mediates non-small cell lung cancer cell-induced angiogenesis

MicroRNAs (miRNAs) expressed in endothelial cells (ECs) are powerful regulators of angiogenesis, which is essential for tumor growth and metastasis. Here, we demonstrated that miR-22 is preferentially and highly expressed in ECs, while its endothelial level is significantly downregulated in human non-small cell lung cancer (NSCLC) tissues when compared to matched nontumor lung tissues. This reduction of endothelial miR-22 is possibly induced by NSCLC cell-secreted interleukin-1β and subsequently activated transcription factor nuclear factor-κB. Endothelial miR-22 functions as a potent angiogenesis inhibitor that inhibits all of the key angiogenic activities of ECs and consequently NSCLC growth through directly targeting sirtuin 1 and fibroblast growth factor receptor 1 in ECs, leading to inactivation of AKT/mammalian target of rapamycin signaling. These findings provide insight into the molecular mechanisms of NSCLC angiogenesis and indicate that endothelial miR-22 represents a potential target for the future antiangiogenic treatment of NSCLC.

Oxidized LDL-regulated microRNAs for evaluating vascular endothelial function: molecular mechanisms and potential biomarker roles in atherosclerosis

As a simple monolayer, vascular endothelial cells can respond to physicochemical stimuli. In addition to promoting the formation of foam cells, oxidized low-density lipoprotein (ox-LDL) contributes to the atherosclerotic process through different mechanisms, including endothelial cell dysfunction. As conserved noncoding RNAs, microRNAs (miRNAs) naturally lie in different genomic positions and post-transcriptionally regulate the expression of many genes. They participate in integrated networks formed under stress to maintain cellular homeostasis, vascular inflammation, and metabolism. These small RNAs constitute therapeutic targets in different diseases, including atherosclerosis, and their role as biomarkers is crucial given their detectability even years before the emergence of diseases. This review was performed to investigate the role of ox-LDL-regulated miRNAs in atherosclerosis, their molecular mechanisms, and their application as biomarkers of vascular endothelial cell dysfunction.

Small extracellular vesicles obtained from hypoxic mesenchymal stromal cells have unique characteristics that promote cerebral angiogenesis, brain remodeling and neurological recovery after focal cerebral ischemia in mice

Obtained from the right cell-type, mesenchymal stromal cell (MSC)-derived small extracellular vesicles (sEVs) promote stroke recovery. Within this process, microvascular remodeling plays a central role. Herein, we evaluated the effects of MSC-sEVs on the proliferation, migration, and tube formation of human cerebral microvascular endothelial cells (hCMEC/D3) in vitro and on post-ischemic angiogenesis, brain remodeling and neurological recovery after middle cerebral artery occlusion (MCAO) in mice. In vitro, sEVs obtained from hypoxic (1% O2), but not 'normoxic' (21% O2) MSCs dose-dependently promoted endothelial proliferation, migration, and tube formation and increased post-ischemic endothelial survival. sEVs from hypoxic MSCs regulated a distinct set of miRNAs in hCMEC/D3 cells previously linked to angiogenesis, three being upregulated (miR-126-3p, miR-140-5p, let-7c-5p) and three downregulated (miR-186-5p, miR-370-3p, miR-409-3p). LC/MS-MS revealed 52 proteins differentially abundant in sEVs from hypoxic and 'normoxic' MSCs. 19 proteins were enriched (among them proteins involved in extracellular matrix-receptor interaction, focal adhesion, leukocyte transendothelial migration, protein digestion, and absorption), and 33 proteins reduced (among them proteins associated with metabolic pathways, extracellular matrix-receptor interaction, focal adhesion, and actin cytoskeleton) in hypoxic MSC-sEVs. Post-MCAO, sEVs from hypoxic MSCs increased microvascular length and branching point density in previously ischemic tissue assessed by 3D light sheet microscopy over up to 56 days, reduced delayed neuronal degeneration and brain atrophy, and enhanced neurological recovery. sEV-induced angiogenesis in vivo depended on the presence of polymorphonuclear neutrophils. In neutrophil-depleted mice, MSC-sEVs did not influence microvascular remodeling. sEVs from hypoxic MSCs have distinct angiogenic properties. Hypoxic preconditioning enhances the restorative effects of MSC-sEVs.

Suppression of choroidal neovascularization by silencing of long non-coding RNA IPW

Long noncoding RNAs (lncRNAs) have emerged as the key regulators in the pathogenesis of human disorders. This study aimed to investigate the role of lncRNA-IPW in the progression of choroidal neovascularization (CNV) and the underlying molecular mechanism. IPW was significantly up-regulated in the choroidal tissues of laser-induced CNV mice and in the endothelial cells in response to hypoxic stress. IPW silencing led to reduced formation of CNV in laser-induced CNV model and ex vivo choroidal sprouting model, which could achieve similar therapeutic effects of anti-VEGF on CNV formation. Silencing or transgenic overexpression of IPW could alter endothelial cell viability, proliferation, migration, and tube formation ability in vitro. Mechanistically, IPW silencing led to increased expression of miR-370. Increased miR-370 could mimic the effects of IPW silencing on CNV formation and endothelial angiogenic phenotypes in vivo and in vitro. This study suggests that IPW silencing is a promising strategy for the treatment of neovascular ocular diseases.

Mechanisms of action of metformin and its regulatory effect on microRNAs related to angiogenesis

Angiogenesis is rapidly initiated in response to pathological conditions and is a key target for pharmaceutical intervention in various malignancies. Anti-angiogenic therapy has emerged as a potential and effective therapeutic strategy for treating cancer and cardiovascular-related diseases. Metformin, a first-line oral antidiabetic agent for type 2 diabetes mellitus (T2DM), not only reduces blood glucose levels and improves insulin sensitivity and exerts cardioprotective effects but also shows benefits against cancers, cardiovascular diseases, and other diverse diseases and regulates angiogenesis. MicroRNAs (miRNAs) are endogenous noncoding RNA molecules with a length of approximately 19-25 bases that are widely involved in controlling various human biological processes. A large number of miRNAs are involved in the regulation of cardiovascular cell function and angiogenesis, of which miR-21 not only regulates vascular cell proliferation, migration and apoptosis but also plays an important role in angiogenesis. The relationship between metformin and abnormal miRNA expression has gradually been revealed in the context of numerous diseases and has received increasing attention. This paper reviews the drug-target interactions and drug repositioning events of metformin that influences vascular cells and has benefits on angiogenesis-mediated effects. Furthermore, we use miR-21 as an example to explain the specific molecular mechanism underlying metformin-mediated regulation of the miRNA signaling pathway controlling angiogenesis and vascular protective effects. These findings may provide a new therapeutic target and theoretical basis for the clinical prevention and treatment of cardiovascular diseases.

Non-Coding RNAs and Hereditary Hemorrhagic Telangiectasia

Non-coding RNAs (ncRNAs) are functional ribonucleic acid (RNA) species that include microRNAs (miRs), a class of short non-coding RNAs (∼21–25 nucleotides), and long non-coding RNAs (lncRNAs) consisting of more than 200 nucleotides. They regulate gene expression post-transcriptionally and are involved in a wide range of pathophysiological processes. Hereditary hemorrhagic telangiectasia (HHT) is a rare disorder inherited in an autosomal dominant fashion characterized by vascular dysplasia. Patients can develop life-threatening vascular malformations and experience severe hemorrhaging. Effective pharmacological therapies are limited. The study of ncRNAs in HHT is an emerging field with great promise. This review will explore the current literature on the involvement of ncRNAs in HHT as diagnostic and pathogenic factors.

Differential Expression of Circulating Plasma miRNA-370 and miRNA-10a from Patients with Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant, vascular disorder that presents with telangiectases and arteriovenous malformations. HHT is a genetically heterogeneous disorder, involving mutations in endoglin (ENG; HHT1) and activin receptor-like kinase 1 (ACVRL1/ALK1; HHT2) genes that account for over 85% of all HHT patients. The current diagnosis of HHT patients remains at the clinical level, but many suspected patients do not have a clear HHT diagnosis or do not show pathogenic mutations in HHT genes. This situation has prompted the search for biomarkers to help in the early diagnosis of the disease. We have analyzed the plasma levels in HHT patients of selected micro-RNAs (miRNAs), small single-stranded RNAs that regulate gene expression at the transcriptional level by interacting with specific RNA targets. A total of 16 HHT1 and 17 HHT2 plasma samples from clinically confirmed patients and 16 controls were analyzed in this study. Total RNA was purified from plasma, and three selected miRNAs (miRNA-10a, miRNA-214, and miRNA-370), related to the pathobiology of cardiovascular diseases and potentially targeting ENG or ALK1, were measured by quantitative polymerase chain reaction. Compared with controls, levels of miRNA-370, whose putative target is ENG, were significantly downregulated in HHT1, but not in HHT2, whereas the levels of miRNA-10a, whose putative target is ALK1, were significantly upregulated in HHT2, but not in HHT1. In addition, the levels of miRNA-214, potentially targeting ENG and ALK1, did not change in either HHT1 or HHT2 patients versus control samples. While further studies are warranted, these results suggest that dysregulated plasma levels of miRNA-370 or miRNA-10a could help to identify undiagnosed HHT1 or HHT2 patients, respectively.

Cholinergic Stress Signals Accompany MicroRNA-Associated Stereotypic Behavior and Glutamatergic Neuromodulation in the Prefrontal Cortex

Stereotypic behavior (SB) is common in emotional stress-involved psychiatric disorders and is often attributed to glutamatergic impairments, but the underlying molecular mechanisms are unknown. Given the neuro-modulatory role of acetylcholine, we sought behavioral-transcriptomic links in SB using TgR transgenic mice with impaired cholinergic transmission due to over-expression of the stress-inducible soluble 'readthrough' acetylcholinesterase-R splice variant AChE-R. TgR mice showed impaired organization of behavior, performance errors in a serial maze test, escape-like locomotion, intensified reaction to pilocarpine and reduced rearing in unfamiliar situations. Small-RNA sequencing revealed 36 differentially expressed (DE) microRNAs in TgR mice hippocampi, 8 of which target more than 5 cholinergic transcripts. Moreover, compared to FVB/N mice, TgR prefrontal cortices displayed individually variable changes in over 400 DE mRNA transcripts, primarily acetylcholine and glutamate-related. Furthermore, TgR brains presented c-fos over-expression in motor behavior-regulating brain regions and immune-labeled AChE-R excess in the basal ganglia, limbic brain nuclei and the brain stem, indicating a link with the observed behavioral phenotypes. Our findings demonstrate association of stress-induced SB to previously unknown microRNA-mediated perturbations of cholinergic/glutamatergic networks and underscore new therapeutic strategies for correcting stereotypic behaviors.

Schnurri-3 regulates BMP9-induced osteogenic differentiation and angiogenesis of human amniotic mesenchymal stem cells through Runx2 and VEGF

Human amniotic mesenchymal stem cells (hAMSCs) are multiple potent progenitor cells (MPCs) that can differentiate into different lineages (osteogenic, chondrogenic, and adipogenic cells) and have a favorable capacity for angiogenesis. Schnurri-3 (Shn3) is a large zinc finger protein related to Drosophila Shn, which is a critical mediator of postnatal bone formation. Bone morphogenetic protein 9 (BMP9), one of the most potent osteogenic BMPs, can strongly upregulate various osteogenesis- and angiogenesis-related factors in MSCs. It remains unclear how Shn3 is involved in BMP9-induced osteogenic differentiation coupled with angiogenesis in hAMSCs. In this investigation, we conducted a comprehensive study to identify the effect of Shn3 on BMP9-induced osteogenic differentiation and angiogenesis in hAMSCs and analyze the responsible signaling pathway. The results from in vitro and in vivo experimentation show that Shn3 notably inhibits BMP9-induced early and late osteogenic differentiation of hAMSCs, expression of osteogenesis-related factors, and subcutaneous ectopic bone formation from hAMSCs in nude mice. Shn3 also inhibited BMP9-induced angiogenic differentiation, expression of angiogenesis-related factors, and subcutaneous vascular invasion in mice. Mechanistically, we found that Shn3 prominently inhibited the expression of BMP9 and activation of the BMP/Smad and BMP/MAPK signaling pathways. In addition, we further found activity on runt-related transcription factor 2 (Runx2), vascular endothelial growth factor (VEGF), and the target genes shared by BMP and Shn3 signaling pathways. Silencing Shn3 could dramatically enhance the expression of Runx2, which directly regulates the downstream target VEGF to couple osteogenic differentiation with angiogenesis. To summarize, our findings suggested that Shn3 significantly inhibited the BMP9-induced osteogenic differentiation and angiogenesis in hAMSCs. The effect of Shn3 was primarily seen through inhibition of the BMP/Smad signaling pathway and depressed expression of Runx2, which directly regulates VEGF, which couples BMP9-induced osteogenic differentiation with angiogenesis.

MicroRNA-574-5p in gastric cancer cells promotes angiogenesis by targeting protein tyrosine phosphatase non-receptor type 3 (PTPN3)

We elucidate in this study that up-regulation of miR-574-5p in gastric cancer cells under hypoxic conditions contributed to angiogenesis. We found that miR-574-5p and HIF-1α were up-regulated in gastric cancer cells cultured under 2% O₂ or in medium containing CoCl_2, and in muscle tissues of mice injected with NaNO₂, indicating up-regulation of miR-574-5p in vitro or in vivo in response to hypoxic conditions. We hypothesized that up-regulation of miR-574-5p could promote angiogenesis. Transfection of gastric cancer cells with miR-574-5p mimics or inhibitor resulted in increase or decrease in the expression of VEGFA. Viability, migration, invasion and tube formation of HUVECs cultured with conditioned medium from SGC/574 cells transfected with miR-574-5p inhibitor were reduced. Tube formation of HUVECs cultured with conditioned medium from SGC-7901 cells transfected with miR-574-5p mimics was increased. An in vivo study demonstrated that inhibition of miR-574-5p in the tumor xenografts of mice reduced the expression of CD31 one of the endothelial cell markers. We identified PTPN3 a tyrosine phosphatase as a target of miR-574-5p that bound to the 3'UTR of PTPN3 mRNA to inhibit the expression of PTPN3. Furthermore, the data in this study demonstrated that inhibition of PTPN3 in gastric cancer cells enhanced phosphorylation of p44/42 MAPKs and promoted angiogenesis. We conclude that miR-574-5p in gastric cancer cells promoted angiogenesis via enhancing phosphorylation of p44/42 MAPKs by miR-574-5p inhibition of PTPN3 expression.