MicroRNA-210: a unique and pleiotropic hypoxamir

Primer for Mainstreaming Mind-Body Techniques for Extreme Climates-Insights and Future Directions

Background: The deprivation of oxygen reaching the tissues (also termed as hypoxia) affects the normal functioning of the body. This results in development of many diseases like ischemia, glaucoma, MCI (Mild Cognitive Impairment), pulmonary and cerebral edema, stress and depression. There are no effective drugs that can treat such diseases. Despite such failure, alternative interventions such as mind-body techniques (MBTs) have not been adequately investigated. Methods: The first part of this review has been focused on philosophical aspects of various MBTs besides evolving an ayurgenomic perspective. The potential of MBTs as a preventive non-pharmacological intervention in the treatment of various general and hypoxic pathologies has been further described in this section. In the second part, molecular, physiological, and neuroprotective roles of MBTs in normal and hypoxic/ischemic conditions has been discussed. Results: In this respect, the importance of and in vivo studies has also been discussed. Conclusions: Although several studies have investigated the role of protective strategies in coping with the hypoxic environment, the efficacy of MBTs at the molecular level has been ignored.

Hypoxia-inducible factors in metabolic reprogramming during sepsis

Sepsis is a highly heterogeneous syndrome that is caused by an imbalanced host response to infection. Despite huge investments, sepsis remains a contemporary threat with significant burden on health systems. Vascular dysfunction and elevated oxygen consumption by highly metabolically active immune cells result in tissue hypoxia during inflammation. The transcription factor hypoxia-inducible factor-1a (HIF1α), and its family members, plays an important role in cellular metabolism and adaptation to cellular stress caused by hypoxia. In this review, we discuss the role of HIF in sepsis. We show possible mechanisms by which the inflammatory response activated during sepsis affects the HIF pathway. The activated HIF pathway in turn changes the metabolism of both innate and adaptive immune cells. As HIF expression in leukocytes of septic patients can be directly linked with mortality, we discuss multiple ways of interfering with the HIF signaling pathway.

The interplay between HIF-1α and noncoding RNAs in cancer

Hypoxia is a classic characteristic of the tumor microenvironment with a significant impact on cancer progression and therapeutic response. Hypoxia-inducible factor-1 alpha (HIF-1α), the most important transcriptional regulator in the response to hypoxia, has been demonstrated to significantly modulate hypoxic gene expression and signaling transduction networks. In past few decades, growing numbers of studies have revealed the importance of noncoding RNAs (ncRNAs) in hypoxic tumor regions. These hypoxia-responsive ncRNAs (HRNs) play pivotal roles in regulating hypoxic gene expression at the transcriptional, posttranscriptional, translational and posttranslational levels. In addition, as a significant gene expression regulator, ncRNAs exhibit promising roles in regulating HIF-1α expression at multiple levels. In this review, we briefly elucidate the reciprocal regulation between HIF-1α and ncRNAs, as well as their effect on cancer cell behaviors. We also try to summarize the complex feedback loop existing between these two components. Moreover, we evaluated the biomarker potential of HRNs for the diagnosis and prognosis of cancer, as well as the potential clinical utility of shared regulatory mechanisms between HIF-1α and ncRNAs in cancer treatment, providing novel insights into tumorigenicity, which may lead to innovative clinical applications.

Accumulation of kynurenine elevates oxidative stress and alters microRNA profile in human bone marrow stromal cells

Kynurenine, a metabolite of tryptophan breakdown, has been shown to increase with age, and plays a vital role in a number of age-related pathophysiological changes, including bone loss. Accumulation of kynurenine in bone marrow stromal cells (BMSCs) has been associated with a decrease in cell proliferation and differentiation, though the exact mechanism by which kynurenine mediates these changes is poorly understood. MiRNAs have been shown to regulate BMSC function, and accumulation of kynurenine may alter the miRNA expression profile of BMSCs. The aim of this study was to identify differentially expressed miRNAs in human BMSCs in response to treatment with kynurenine, and correlate miRNAs function in BMSCs biology through bioinformatics analysis. Human BMSCs were cultured and treated with and without kynurenine, and subsequent miRNA isolation was performed. MiRNA array was performed to identify differentially expressed miRNA. Microarray analysis identified 50 up-regulated, and 36 down-regulated miRNAs in kynurenine-treated BMSC cultures. Differentially expressed miRNA included miR-1281, miR-330-3p, let-7f-5p, and miR-493-5p, which are important for BMSC proliferation and differentiation. KEGG analysis found up-regulated miRNA targeting glutathione metabolism, a pathway critical for removing oxidative species. Our data support that the kynurenine dependent degenerative effect is partially due to changes in the miRNA profile of BMSCs.

Effects of hypoxic-ischemic pre-treatment on microvesicles derived from endothelial progenitor cells

Endothelial progenitor cells (EPCs) have protective roles in ischemic injury due to their ability to improve endothelial function and modulate angiogenesis. Microvesicles (MVs) are small membrane particles released by various cell types, including EPCs, which affect various target cells by transferring carried genetic information, including microRNAs (miRNAs/miRs). Depending on the stimuli and cell types, MVs exert different functions. In the present study, oxygen-glucose deprivation (OGD) was used to mimic ischemic-hypoxic (HI) insult, where the effects of HI insult on EPC-derived MVs (EPC-MVs) were subsequently investigated. OGD induced Ca²⁺ influx in EPCs and increased the release of EPC-MVs compared with normoxic conditions. In addition, MVs prepared from EPCs cultured under normoxic conditions or OGD conditions (OGD-EMVs) had the ability to stimulate the proliferation of EPCs. Furthermore, OGD-EMVs induced stronger effects on proliferation, which may be associated with the upregulation of miR-210 in EPC-MVs. In conclusion, the present results indicated that HI insult promoted the release of MVs from EPCs and upregulated miR-210 in MVs, leading to positive modulation of the proliferation of EPCs cultured under normoxic conditions.

Expressions of miR-21 and miR-210 in Breast Cancer and Their Predictive Values for Prognosis

BACKGROUND

We aimed to investigate the expressions of miR-21 and miR-210 in the breast cancer tissue and their correlation with clinicopathological features and prognosis.

METHODS

A retrospective analysis was performed on 68 patients with breast cancer treated surgically in Wuhan General Hospital of Guangzhou Military in 2014-2015. The breast cancer tissue and the adjacent normal tissue were collected from the patients. Quantitative real-time PCR (qRT-PCR) was used to detect the expression levels of miR-21 and miR-210 in the breast cancer and adjacent normal tissues.

RESULTS

According to qRT-PCR, the expression levels of miR-210 and miR-21 in the breast cancer tissue were significantly higher than those in the adjacent normal tissue (P<0.05), which were significantly correlated with lymph node metastasis, clinical staging and differentiation of patients (P<0.05). miR-21 and miR-210 were significantly positive correlated in both breast cancer tissues and adjacent normal tissues (r=0.7014, 0.7502, P<0.001). The survival rate in the miR-210 high expression group was significantly lower than that in the miR-210 low expression group (P<0.05), whereas there was no significant difference between the miR-21 high and low expression groups.

CONCLUSION

miR-21 and miR-210 are highly expressed in the breast cancer tissue and significantly correlated with lymph node metastasis, clinical staging and differentiation. miR-210, the up-regulated expression of which is related to the poor prognosis of patients with breast cancer, may be a potential prognostic indicator for breast cancer, which can be used to judge the prognosis.

Cardiac shock wave therapy protects cardiomyocytes from hypoxia‑induced injury by modulating miR‑210

Cardiac shock wave therapy (SWT) has been described as a novel therapeutic strategy that is able to alleviate myocardial ischemic injury. microRNA (miRNA/miR)‑210 plays a cytoprotective role in cardiomyocytes in response to hypoxia by regulating cell apoptosis. The aim of the present study was to investigate whether cardiac SWT could protect cardiomyocytes from hypoxia‑induced injury by regulating miR‑210 expression. The murine adult cardiomyocyte cell line HL‑1 was incubated for 5 h in hypoxic conditions, followed by reoxygenation for 12 h and treatment with SWT immediately following hypoxia in the present study. The cell viability was determined using an MTS assay. Western blot analyses were performed in order to detect cell signaling changes. Reactive oxygen species production was detected using dihydroethidium staining, and malondialdehyde levels were measured using the thiobarbituric acid method. miRNA and mRNA expression levels were confirmed via reverse transcription‑quantitative PCR. Apoptosis was evaluated by means of flow cytometry. HL‑1 cells were then transfected with miR‑210 mimics or inhibitors in order to alter miR‑210 expression levels, and the effects on HL‑1 cells were determined. Hypoxia led to elevated oxidative stress, enhanced cell apoptosis and upregulated miR‑210 expression levels in HL‑1 cells, while SWT could alleviate hypoxia‑induced cell injury and further promote miR‑210 expression. miR‑210 overexpression decreased apoptosis and oxidative stress during hypoxic stress in HL‑1 cells, whereas inhibition of miR‑210 increased cell apoptosis and promoted oxidative stress. Furthermore, miR‑210 inhibition could reverse the effects of SWT on HL‑1 cells. Finally, the mRNA analysis revealed that SWT significantly attenuated apoptosis‑inducing factor mitochondrion‑associated 3 and caspase 8 associated protein 2 mRNA expression levels in cardiomyocytes exposed to hypoxia, which were two targets of miR‑210. SWT could exert cardioprotective effects against hypoxia‑induced cardiac injury by modulating miR‑210.

The role of epigenetic changes in preeclampsia

Preeclampsia (PE) is a disorder affecting 2-10% of pregnancies and has a major role for perinatal and maternal mortality and morbidity. PE can be occurred by initiation of new hypertension combined with proteinuria after 20 weeks gestation, as well as various reasons such as inflammatory cytokines, poor trophoblast invasion can be related with PE disease. Environmental factors can cause epigenetic changes including DNA methylation, microRNAs (miRNAs), and histone modification that may be related to different diseases such as PE. Abnormal DNA methylation during placentation is the most important epigenetic factor correlated with PE. Moreover, changes in histone modification like acetylation and also the effect of overregulation or low regulation of miRNAs or long noncoding RNAs on variety signaling pathways can be resulted in PE. The aim of this review is to describe of studies about epigenetic changes in PE and its therapeutic strategies.

Hypoxia drives cardiac miRNAs and inflammation in the right and left ventricle

Alveolar and myocardial hypoxia may be causes or sequelae of pulmonary hypertension (PH) and heart failure. We hypothesized that hypoxia initiates specific epigenetic and transcriptional, pro-inflammatory programs in the right ventricle (RV) and left ventricle (LV). We performed an expression screen of 750 miRNAs by qPCR arrays in the murine RV and LV in normoxia (Nx) and hypoxia (Hx; 10% O₂ for 18 h, 48 h, and 5d). Additional validation included single qPCR analysis of miRNA and pro-inflammatory transcripts in murine and human RV/LV, and neonatal rat cardiomyocytes (NRCMs). Differential qPCR-analysis (Hx vs. Nx in RV, Hx vs. Nx in LV, and RV vs. LV in Hx) identified nine hypoxia-regulated miRNAs: let-7e-5p, miR-29c-3p, miR-127-3p, miR-130a-3p, miR-146b-5p, miR-197-3p, miR-214-3p, miR-223-3p, and miR-451. Hypoxia downregulated miR-146b in the RV (p < 0.01) and, less so, in the LV (trend; p = 0.28). In silico alignment showed significant binding affinity of miR-146b-5p sequence with the 3'UTR of TRAF6 known to be upstream of pro-inflammatory NF-kB. Consistently, hypoxia induced TRAF6, IL-6, CCL2(MCP-1) in the mouse RV and LV. Incubating neonatal rat cardiomyocytes with pre-miR-146b led to a downregulation of TRAF6, IL-6, and CCL2(MCP-1). TRAF6 mRNA expression was also increased by 3-fold in the RV and LV of end-stage idiopathic pulmonary arterial hypertension (PAH) patients vs. non-PAH controls. We identified hypoxia-regulated, ventricle-specific miRNA expression profiles in the adult mouse heart in vivo. Hypoxia suppresses miR-146b, thus de-repressing TRAF6, and inducing pro-inflammatory IL-6 and CCL2(MCP-1). This novel hypoxia-induced miR-146b-TRAF6-IL-6/CCL2(MCP-1) axis likely drives cardiac fibrosis and dysfunction, and may lead to heart failure. KEY MESSAGES: Chouvarine P, Legchenko E, Geldner J, Riehle C, Hansmann G. Hypoxia drives cardiac miRNAs and inflammation in the right and left ventricle. • Hypoxia drives ventricle-specific miRNA profiles, regulating cardiac inflammation. • miR-146b-5p downregulates TRAF6, known to act upstream of pro-inflammatory NF-κB. • Hypoxia downregulates miR-146b and induces TRAF6, IL-6, CCL2 (MCP-1) in the murine RV and LV. • The inhibitory regulatory effects of miR-146b are confirmed in primary rat cardiomyocytes (pre-miR, anti-miR) and human explant heart tissue (endstage pulmonary arterial hypertension). • A novel miR-146b-TRAF6-IL-6/CCL2(MCP-1) axis likely drives cardiac inflammation, fibrosis and ventricular dysfunction.

HIF-1α Stabilization Increases miR-210 Eliciting First Trimester Extravillous Trophoblast Mitochondrial Dysfunction

Preeclampsia is associated with first trimester placental dysfunction. miR-210, a small non-coding RNA, is increased in the preeclamptic placenta. The effects of elevated miR-210 on placental function remain unclear. The objectives of this study were to identify targets of miR-210 in first trimester primary extravillous trophoblasts (EVTs) and to investigate functional pathways altered by elevated placental miR-210 during early pregnancy. EVTs isolated from first trimester placentas were exposed to cobalt chloride (CoCl₂), a HIF-1α stabilizer and hypoxia mimetic, and miR-210 expression by qPCR, HIF1α protein levels by western blot and cell invasion were assessed. A custom TruSeq RNA array, including all known/predicted miR-210 targets, was run using miR-210 and miR-negative control transfected EVTs. Mitochondrial function was assessed by high resolution respirometry in transfected EVTs. EVTs exposed to CoCl₂ showed a dose and time-dependent increase in miR-210 and HIF1α and reductions in cell invasion. The TruSeq array identified 49 altered genes in miR-210 transfected EVTs with 27 genes repressed and 22 enhanced. Three of the top six significantly repressed genes, NDUFA4, SDHD, and ISCU, are associated with mitochondrial function. miR-210 transfected EVTs had decreased maximal, complex II and complex I+II mitochondrial respiration. This study suggests that miR-210 alters first trimester trophoblast function. miR-210 overexpression alters EVT mitochondrial function in early pregnancy. Mitochondrial dysfunction may lead to increased reactive oxygen species, trophoblast cell damage and likely contributes to the pathogenesis of preeclampsia.

MicroRNA-210 regulates human trophoblast cell line HTR-8/SVneo function by attenuating Notch1 expression: Implications for the role of microRNA-210 in pre-eclampsia

Successful pregnancy depends on the precise regulation of extravillous trophoblast cell invasion ability. MicroRNA-210-3p (miR-210), which is increased in the placenta of pre-eclampsia. Furthermore, miR-210 could inhibit trophoblasts invasion and might act as a serum biomarker for pre-eclampsia. Previous studies have demonstrated that miR-210 regulates HUVEC (human umbilical vein endothelial cell)-mediated angiogenesis by regulating the NOTCH1 signaling pathway. Studies by our group have previously identified that NOTCH1 plays a positive role in regulating trophoblast functions. However, the miR-210/NOTCH1 signaling pathway in the regulation of trophoblasts and pre-eclampsia has not been characterized. Therefore, this study was conducted to investigate the role of miR-210 and its relationship with NOTCH1 in trophoblasts. We first examined the expression levels of miR-210 and NOTCH1 in pre-eclamptic and normals placentas. Next, the expression and location of miR-210 and NOTCH1 in the first-trimester villi, maternal decidua, and placenta of late pregnancy were shown via in situ hybridization and immunohistochemistry. The trophoblast cell line HTR-8/SVneo was used to investigate the effects of miR-210 on the expression of NOTCH1 and cell bioactivity by upregulation and downregulation strategies. The results showed that miR-210 expression was increased, whereas NOTCH1 expression was decreased in pre-eclamptic placenta compared with controls. Upregulation of miR-210 decreased NOTCH1 expression, impaired HTR-8/SVneo proliferation, migration, invasion, and tube-like formation capabilities, and promoted apoptosis. In contrast, downregulation of miR-210 resulted in the opposite effects. These findings suggested that miR-210 might act as a contributor to trophoblast dysfunction by attenuating NOTCH1 expression.

MicroRNA-210-3p Targets RGMA to Enhance the Angiogenic Functions of Endothelial Progenitor Cells Under Hypoxic Conditions

Endothelial progenitor cells (EPCs) are multipotential stem cells considered to have immense clinical value for revascularization. However, the clinical application of EPCs has been hampered by their clinical potency in ischemic anoxic environments. This study aimed to explore the effect of microRNA-210 (miR-210) on EPCs under oxygen-glucose deprivation (OGD) conditions. We generated a model of EPCs cultured under OGD conditions to simulate ischemia and explore the expression of miR-210 in vitro. With longer exposure to hypoxia, we found that miR-210-3p expression was highly upregulated in OGD groups compared to that in controls from 4 to 24 h, but not miR-210-5p. We then transfected a miR-210-3p mimic and inhibitor into EPCs, and after 24 h, we exposed them to OGD conditions for 4 h to simulate ischemia. We detected miR-210 by real-time polymerase chain reaction (RT-PCR) and tested the proliferation, migration, and tube formation of normal EPCs and OGD-treated EPCs by CCK-8, transwell chamber, and Matrigel assays, respectively. The direct targets of miR-210-3p were predicted using miRWalk. Compared to that in normal EPCs, higher miR-210-3p expression was found in OGD-treated EPCs (p < 0.05). Moreover, upregulation of miR-210-3p was found to promote proliferation, migration, and tube formation in EPCs under normal and OGD conditions (p < 0.05), whereas down-regulation inhibited these abilities in OGD-treated EPCs (p < 0.05). Repulsive guidance molecule A (RGMA), a negative regulator of angiogenesis, was predicted to be a target of miR-210-3p. Accordingly, upregulation of miR-210-3p was found to inhibit its expression at the protein level in OGD-treated EPCs, whereas downregulation of miR-210-3p inhibited its expression (p < 0.05). A dual-luciferase reporter system confirmed that RGMA is a direct target of miR-210-3p. MicroRNA-210-3p overexpression enhances the angiogenic properties of OGD-treated EPCs by inhibiting RGMA.

The molecular rationale for therapeutic targeting of glutamine metabolism in pulmonary hypertension

INTRODUCTION

Pulmonary hypertension (PH) is a deadly enigmatic disease with increasing prevalence. Cellular pathologic hallmarks of PH are driven at least partly by metabolic rewiring, but details are just emerging. The discovery that vascular matrix stiffening can mechanically activate the glutaminase (GLS) enzyme and serve as a pathogenic mechanism of PH has advanced our understanding of the complex role of glutamine in PH. It has also offered a novel therapeutic target for development as a next-generation drug for this disease. Area covered: This review discusses the cellular contribution of glutamine metabolism to PH together with the possible therapeutic application of pharmacologic GLS inhibitors in this disease. Expert opinion: Despite advances in our understanding of glutamine metabolism in PH, questions remain unanswered regarding the development of therapies targeting glutamine in PH. The comprehensive mechanisms by which glutamine metabolism rewiring influences pulmonary vascular cell behavior to drive PH are incompletely understood. Because glutamine metabolism exhibits a variety of functions in organ repair and homeostasis, a better understanding of the overall risk-benefit ratio of these strategies with long-term follow-up is needed. This knowledge should pave the way for the design of new strategies to prevent and hopefully even regress PH.

miR‑210‑3p regulates cell growth and affects cisplatin sensitivity in human ovarian cancer cells via targeting E2F3

The potential role of microRNA (miR)‑210‑3p in carcinogenesis and the cisplatin sensitivity of ovarian cancer were evaluated in the present study. The relative expression levels of miR‑210‑3p in cisplatin‑sensitive SKOV‑3 cells and cisplatin‑resistant SKOV‑3/DDP cells were determined using reverse transcription‑quantitative polymerase chain reaction analysis. miR‑210‑3p mimics and inhibitors were transfected into SKOV‑3/DDP cells. Cell Counting Kit‑8, scratch and Transwell invasion assays and flow cytometry were conducted to evaluate the role of miR‑210‑3p in ovarian cancer cells. A luciferase reporter assay was used to verify the association between miR‑210‑3p and E2F transcription factor 3 (E2F3). Drug sensitivity was evaluated by treating the cells with cisplatin. The expression level of miR‑210‑3p was lower in SKOV‑3/DDP cells than in SKOV‑3 cells. Compared with the untransfected control, SKOV‑3 cells transfected with miR‑210‑3p exhibited a significantly higher survival rate. The overexpression of miR‑210‑3p inhibited SKOV‑3/DDP cell proliferation, migration and invasion, and promoted cell apoptosis. By contrast, the inhibition of miR‑210‑3p promoted cell migration and invasion. The luciferase reporter assay confirmed that E2F3 was a direct target gene of miR‑210‑3p. Cisplatin treatment resulted in a sharp decrease in the survival rate of SKOV‑3/DDP cells transfected with the miR‑210‑3p mimics. The decrease in cell survival rate caused by the overexpression of miR‑210‑3p was rescued by the overexpression of E2F3 in SKOV‑3/DDP cells. Taken together, these results suggest that miR‑210‑3p may act as a tumor suppressor in ovarian cancer cells and affect the sensitivity of cells to cisplatin by directly targeting E2F3. This indicates its potential use as a therapeutic target for improving drug resistance in ovarian cancer.

Emerging Roles of miRNAs in Brain Development and Perinatal Brain Injury

In human beings the immature brain is highly plastic and depending on the stage of gestation is particularly vulnerable to a range of insults that if sufficiently severe, can result in long-term motor, cognitive and behavioral impairment. With improved neonatal care, the incidence of major motor deficits such as cerebral palsy has declined with prematurity. Unfortunately, however, milder forms of injury characterized by diffuse non-cystic white matter lesions within the periventricular region and surrounding white matter, involving loss of oligodendrocyte progenitors and subsequent axonal hypomyelination as the brain matures have not. Existing therapeutic options for treatment of preterm infants have proved inadequate, partly owing to an incomplete understanding of underlying post-injury cellular and molecular changes that lead to poor neurodevelopmental outcomes. This has reinforced the need to improve our understanding of brain plasticity, explore novel solutions for the development of protective strategies, and identify biomarkers. Compelling evidence exists supporting the involvement of microRNAs (miRNAs), a class of small non-coding RNAs, as important post-transcriptional regulators of gene expression with functions including cell fate specification and plasticity of synaptic connections. Importantly, miRNAs are differentially expressed following brain injury, and can be packaged within exosomes/extracellular vesicles, which play a pivotal role in assuring their intercellular communication and passage across the blood-brain barrier. Indeed, an increasing number of investigations have examined the roles of specific miRNAs following injury and regeneration and it is apparent that this field of research could potentially identify protective therapeutic strategies to ameliorate perinatal brain injury. In this review, we discuss the most recent findings of some important miRNAs in relation to the development of the brain, their dysregulation, functions and regulatory roles following brain injury, and discuss how these can be targeted either as biomarkers of injury or neuroprotective agents.

Noncoding RNAs in the Vascular System Response to Oxidative Stress

SIGNIFICANCE

Redox homeostasis plays a pivotal role in vascular cell function and its imbalance has a causal role in a variety of vascular diseases. Accordingly, the response of mammalian cells to redox cues requires precise transcriptional and post-transcriptional modulation of gene expression patterns. Recent Advances: Mounting evidence shows that nonprotein-coding RNAs (ncRNAs) are important for the functional regulation of most, if not all, cellular processes and tissues. Not surprisingly, a prominent role of ncRNAs has been identified also in the vascular system response to oxidative stress.

CRITICAL ISSUES

The highly heterogeneous family of ncRNAs has been divided into several groups. In this article we focus on two classes of regulatory ncRNAs: microRNAs and long ncRNAs (lncRNAs). Although knowledge in many circumstances, and especially for lncRNAs, is still fragmentary, ncRNAs are clinically interesting because of their diagnostic and therapeutic potential. We outline ncRNAs that are regulated by oxidative stress as well as ncRNAs that modulate reactive oxygen species production and scavenging. More importantly, we describe the role of these ncRNAs in vascular physiopathology and specifically in disease conditions wherein oxidative stress plays a crucial role, such as hypoxia and ischemia, ischemia reperfusion, inflammation, diabetes mellitus, and atherosclerosis.

FUTURE DIRECTIONS

The therapeutic potential of ncRNAs in vascular diseases and in redox homeostasis is discussed.

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.

MiR-210-3p protects endometriotic cells from oxidative stress-induced cell cycle arrest by targeting BARD1

Endometriosis is associated with benign but adversely developed cysts in the extrauterine environment. The oxidative imbalanced environment induces DNA damage and affects cell cycle progression of endometrial stromal cells (ESCs) and endometrial epithelial cells, but how endometriotic cells maintain proliferation in the presence of oxidative stress is not clear. Growing evidence has indicated that the ectopic hypoxic microenvironment and oxidative stress can stimulate the growth of endometriotic cells, which is mainly due to the increase of HIF-1α. We found that the master hypoxia-associated miRNA miR-210-3p was increased in stromal and glandular cells of ectopic lesions compared with that of eutopic and normal endometria and was consistent with the expression of HIF-1α and the local oxidative stress-induced DNA damage predictor 8-OHdG. Moreover, miR-210-3p was upregulated in ESCs and Ishikawa cells under hypoxic conditions but not in normoxic culture. Knockdown of miR-210-3p induced a G2/M arrest of ESCs and Ishikawa cells under hypoxia, while no effect was found under normoxia. BARD1 was identified as a target of miR-210-3p. BARD1 expression was decreased in endometriotic tissues compared with eutopic and normal endometria and negatively correlated with the expression of miR-210-3p. Multivariate regression analysis showed that BARD1 downregulation could serve as an indicator for endometriotic severity. Our results suggest that miR-210-3p attenuates the G2/M cell cycle checkpoint by inactivating BRCA1 complex function in response to DNA damage under hypoxia via targeting the 3′ untranslated region of BARD1 mRNA. Endometriotic mouse model experiments showed that intraperitoneal injection of the miR-210-3p inhibitor or vitamin C suppressed the growth of endometriotic lesions. Together, our results demonstrate that endometriotic cells inhibit BARD1/BRCA1 function by upregulating miR-210-3p, which might be the underlying mechanism for endometriotic cell maintenance of growth in oxidative stress. Furthermore, inhibition of miR-210-3p and administration of vitamin C are promising approaches for the treatment of endometriosis.

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.

Monogenic, Polygenic, and MicroRNA Markers for Ischemic Stroke

Ischemic stroke (IS) is a leading disease with high mortality and disability, as well as with limited therapeutic window. Biomarkers for earlier diagnosis of IS have long been pursued. Family and twin studies confirm that genetic variations play an important role in IS pathogenesis. Besides DNA mutations found previously by genetic linkage analysis for monogenic IS (Mendelian inheritance), recent studies using genome-wide associated study (GWAS) and microRNA expression profiling have resulted in a large number of DNA and microRNA biomarkers in polygenic IS (sporadic IS), especially in different IS subtypes and imaging phenotypes. The present review summarizes genetic markers discovered by clinical studies and discusses their pathogenic molecular mechanisms involved in developmental or regenerative anomalies of blood vessel walls, neuronal apoptosis, excitotoxic death, inflammation, neurogenesis, and angiogenesis. The possible impact of environment on genetics is addressed as well. We also include a perspective on further studies and clinical application of these IS biomarkers.

Circulating exosomal and Argonaute-bound microRNAs in preeclampsia

INTRODUCTION

microRNAs (miRNAs) play important role in the regulation of placental development, and abnormal miRNA expression is associated with preeclampsia (PE). miRNAs are released from trophoblast cells to maternal blood flow, where they are highly stable, being encapsulated inside extracellular vesicles, like exosomes or bound to Argonaute proteins. In PE, placental dysfunction leads to aberrant extracellular miRNA secretion. hsa-miR-210 is a hypoxia-sensitive miRNA found to be upregulated in PE; however, it is unknown whether it is the cause or the consequence of the disease.

OBJECTIVE

Our aim was to analyze the expression of several miRNAs, including hsa-miR-210 in placenta, exosome and Ago-bound fractions comparing normal (N) and PE pregnancies. We performed in vitro analyses of extracellular hsa-miR-210 secretion of trophoblast cell cultures (of villous and extravillous origin) under hypoxic condition.

METHODS

PE and N placenta samples were collected from C-sections, and blood samples were drawn from each pregnant woman in the third trimester. HTR-8 and JAR cell lines were cultured in exosome-free media and treated with hypoxia-mimetic agents. Exosome and Ago-bound fractions were isolated by membrane affinity spin column method from plasma and cell media. Short RNAs were extracted from exosomes and vesicle-free fractions, and total-RNA was isolated from the placenta samples. The RNA purity and concentration were measured by spectrophotometry. Expression analysis was carried out by qPCR with specific primers to target and reference miRNAs.

RESULTS

The level of hsa-miR-210 was significantly higher in PE placentas, which could cause a minor increase of exosomal and a high elevation of Ago-bound miR-210 in circulation. Hypoxia lead to intracellular hsa-miR-210 upregulation in trophoblast cell lines. In extravillous cell (HTR-8) media, only the level of exosomal hsa-miR-210 was increased but no change in Ago-bound hsa-miR-210 level was observed. In contrast, in villous cell (JAR) media, the level of exosomal hsa-miR-210 was increased and enhanced release of Ago-bound hsa-miR-210 was also observed.

CONCLUSION

Based on our data, we postulate that in PE, exosomal hsa-miR-210 is secreted actively from the trophoblast, and by intercellular communication, it may have a role in disease etiology. In addition, there is a passive release of Ago-bound hsa-miR-210 into the circulation, which may represent by-products of cell-death and is thereby a possible consequence of the disease.

Potential role for microRNA in facilitating physiological adaptation to hypoxia in the Pacific whiteleg shrimp Litopenaeus vannamei

Hypoxia is one of the most common physiological stressors in shrimp farming. Post-transcriptional regulation by microRNAs has been recognized as a ubiquitous strategy to enable transient phenotypic plasticity and adaptation to stressful environment, but involvement of microRNAs in hypoxia stress response of penaeid shrimp remains elusive. In this study, small RNA sequencing and comparative transcriptomic analysis was conducted to construct a comprehensive microRNA dataset for the whiteleg shrimp Litopenaeus vannamei exposed to hypoxia challenge. A total of 3324 known miRNAs and 8 putative novel miRNAs were identified, providing a valuable resource for future investigation on the functional mechanism of miRNAs in shrimp. Upon hypoxia, 1213 miRNAs showed significant differential expression, and many well-known miRNAs involved in hypoxia tolerance such as miR-210, let-7, miR-143 and miR-101 were identified. Remarkably, the vast majority of these miRNAs were up-regulated, suggesting that up-regulation of miRNAs may represent an effective strategy to inhibit protein translation under stressful hypoxic condition. The differentially expressed miRNAs were potentially targeting a wide variety of genes, including those with essential roles in hypoxia tolerance such as HIF1a and p53. GO and KEGG enrichment analysis further revealed that a broad range of biological processes and metabolic pathways were over-represented. Several GO terms associated with gene transcription and translation and KEGG pathways related to cytoskeleton remodeling, immune defense and signaling transduction were enriched, highlighting the crucial roles of these cellular events in the adaptation to hypoxia. Taken together, our study revealed that the differentially expressed miRNAs may regulate host response to hypoxia by modulating the expression of stress response genes such as HIF1a and p53 and affecting key cellular events involved in hypoxia adaptation. The findings would expand our knowledge of the biochemical and molecular underpinnings of hypoxia response strategies used by penaeid shrimp, and contribute to a better understanding of the molecular mechanisms of hypoxia tolerance in decapod crustaceans.

Myocardial Ischemia and Diabetes Mellitus: Role of Oxidative Stress in the Connection between Cardiac Metabolism and Coronary Blood Flow

Ischemic heart disease (IHD) has several risk factors, among which diabetes mellitus represents one of the most important. In diabetic patients, the pathophysiology of myocardial ischemia remains unclear yet: some have atherosclerotic plaque which obstructs coronary blood flow, others show myocardial ischemia due to coronary microvascular dysfunction in the absence of plaques in epicardial vessels. In the cross-talk between myocardial metabolism and coronary blood flow (CBF), ion channels have a main role, and, in diabetic patients, they are involved in the pathophysiology of IHD. The exposition to the different cardiovascular risk factors and the ischemic condition determine an imbalance of the redox state, defined as oxidative stress, which shows itself with oxidant accumulation and antioxidant deficiency. In particular, several products of myocardial metabolism, belonging to oxidative stress, may influence ion channel function, altering their capacity to modulate CBF, in response to myocardial metabolism, and predisposing to myocardial ischemia. For this reason, considering the role of oxidative and ion channels in the pathophysiology of myocardial ischemia, it is allowed to consider new therapeutic perspectives in the treatment of IHD.

HBV infection suppresses the expression of inflammatory macrophage miR‑210

It has been previously reported that hepatitis B e‑antigen (HBeAg) induces microRNA (miR)‑155 expression and promotes liver injury by increasing inflammatory cytokine production in macrophages. Moreover, it was previously demonstrated that miR‑210 alleviates lipopolysaccharide‑stimulated proinflammatory cytokine production in macrophages. In addition, accumulating evidence suggests that miR‑210 is able to suppress hepatitis B virus (HBV) replication in HepG2.2.15 cells. However, it remains unclear whether miR‑210, similar to miR‑155, affects the progress of hepatitis B by regulating macrophage function. Reverse transcription‑quantitative polymerase chain reaction analysis was used to detect miR‑210 levels in serum and cells. HBV‑associated antigens stimulated different types of macrophages and facilitated the observation of the effects of these antigens on miR‑210 expression in macrophages. Co‑culture of peripheral blood monocytes from healthy controls and the serum of patients with chronic hepatitis B (CHB) was conducted to evaluate the effect of HBV‑associated elements in the serum on the expression of the macrophage miR‑210 in vivo. It was observed that miR‑210 expression levels were decreased in the peripheral blood monocytes (PBMs) and serum of patients with CHB and negatively associated with serum alanine aminotransferase and aspartate aminotransferase, but not other clinical parameters including hepatitis B surface antigen (HBsAg), HBeAg, anti‑HBe antibody (HBeAb) and hepatitis B core antibody (HBcAb) and HBV‑DNA. Notably, it was demonstrated that miR‑210 expression was not affected by treatment with HBV‑associated antigens in different types of macrophages. Notably, the serum of patients with CHB was able to markedly downregulate the miR‑210 expression of PBMs in healthy controls. These findings suggested that, unlike the induction of miR‑155 by HBeAg, there may be certain other elements, apart from HBV‑associated antigens, regulating miR‑210 levels in the serum and PBMs of patients with CHB that affect macrophage activation.

MicroRNA-210 expression during childbirth and postpartum as a potential biomarker of acute fetal hypoxia

OBJECTIVE

To explore whether miR-210 expression can be used as a diagnostic and prognostic marker in acute fetal hypoxia.

METHODS

Whole blood samples of 29 women and their fetuses without hypoxia and 24 women and their fetuses with hypoxia were analysed in this study. Reverse transcription and quantitative real-time PCR were used to measure the expression of miR-210. Expression level differences between the control and hypoxic group in labour time and postpartum change fold were analyzed by standard statistical tests.

RESULTS

We confirmed that miR-210 is significantly more upregulated in fetal blood with acute hypoxia when compared to maternal blood (P Conclusions: Our study confirmed miR-210 upregulation in the blood of pregnant women with acute fetal hypoxia at the time of labour compared to pregnant women without acute fetal hypoxia. Additional investigation should be done to determine miR-210 clearance and the possibility of using miR-210 as a diagnostic and prognostic marker.

Role of microRNAs in inner ear development and hearing loss

The etiology of hearing loss tends to be multi-factorial and affects a significant proportion of the global population. Despite the differences in etiology, a common physical pathological change that leads to hearing loss is damage to the mechanosensory hair cells of the inner ear. MicroRNAs (miRNAs) have been shown to play a role in inner ear development and thus, may play a role in the development or prevention of hearing loss. In this paper, we review the mechanism of action of miRNAs in the auditory system. We present an overview about the role of miRNAs in inner ear development, summarize the current research on the role of miRNAs in gene regulation, and discuss the effects of both miRNA mutations as well as overexpression. We discuss the crucial role of miRNAs in ensuring normal physiological development of the inner ear. Any deviation from the proper function of miRNA in the cochlea seems to contribute to deleterious damage to the structure of the auditory system and subsequently results in hearing loss. As interest for miRNA research increases, this paper serves as a platform to review current understandings and postulate future avenues for research. A better knowledge about the role of miRNA in the auditory system will help in developing novel treatment modalities for restoring hearing function based on regeneration of damaged inner ear hair cells.

Assessment of Correlation Between miR-210 Expression and Pre-Eclampsia Risk: A Meta-Analysis

BACKGROUND

Pre-eclampsia (PE) is a pregnancy disorder characterized by hypertension and proteinuria. The evidence has suggested that microRNAs (miRs) are associated with pre-eclampsia pathogenesis; however, these results are inconsistent. The aim of this study was to assess the association between miR-210 expression and PE risk.

METHODS

Previous studies were selected using PubMed, Scopus, MEDLINE, EMBASE, Science Direct, Google Scholar, Directory of Open Access Journals (DOAJ), and Scientific Information Database (SID). This metaanalysis includes 12 studies associated with miR-210 and pre-eclampsia and necessary information was extracted.

RESULTS

The standardized mean differences [(SMD (0.32) 95% CI (014-0.49), p=0.97] and heterogeneity were determined with the chi-square test (Q=3.63 df =11 p= 0.97), which found no heterogeneity between these studies. Additionally, publication bias was evaluated by Egger's and Begg´s tests. Visual inspection of the funnel plot graphically, and statistically with Egger's weighted regression [(p= 0.35) (95% CI -0.90 - 2.29)] and Begg's rank correlation (p= 0.21), found no important publication bias between studies within the meta-analysis.

CONCLUSION

Our findings suggest that miR-210 contributes to the pathogenesis of PE; therefore, miR-210 could serve as a novel biomarker to predict PE pathophysiology. Further studies are required in this field to characterize the mechanism involved in this process.

Cholangiocarcinoma therapy with nanoparticles that combine downregulation of MicroRNA-210 with inhibition of cancer cell invasiveness

Cholangiocarcinoma (CCA) is the second most common primary liver malignancy with extremely poor therapeutic outcome due to high drug resistance, widespread metastasis and lack of effective treatment options. CCA progression and metastasis are regulated by multiple biological factors including multiple miRNAs and chemokine receptor CXCR4. The goal of this study was to test if nanotherapeutic blockade of CXCR4 by polymeric CXCR4 antagonist (PCX) combined with inhibition of hypoxia-inducible miR-210 cooperatively enhances therapeutic efficacy in CCA through reducing invasiveness, inducing cell killing, and reversing drug resistance. Methods: We first tested the activity of PCX to inhibit migration of CCA cells. We then prepared PCX/anti-miRNA nanoparticles and analyzed their miRNA delivery efficacy and anticancer activity in vitro. Finally, in vivo biodistribution assay and anticancer activity study were performed in CCA tumor-bearing mice. Results: Our results show that PCX had a broad inhibitory effect on cell migration, effectively delivered anti-miR-210, and downregulated miR-210 expression in CCA cells. Combination PCX/anti-miR-210 nanoparticles showed cytotoxic activity towards CCA cells and reduced the number of cancer stem-like cells. The nanoparticles reversed hypoxia-induced drug resistance and sensitized CCA cells to standard gemcitabine and cisplatin combination treatment. Systemic intravenous treatment with the nanoparticles in a CCA xenograft model resulted in prominent combined antitumor activity. Conclusion: Our findings support PCX-based nanoparticles as a promising delivery platform of therapeutic miRNA in combination CCA therapies.

Integrative analysis of dysregulated microRNAs and mRNAs in multiple recurrent synchronized renal tumors from patients with von Hippel-Lindau disease

Von Hippel-Lindau (VHL) disease is a rare auto-somal dominant syndrome that is the main cause of inherited clear-cell renal cell carcinoma (ccRCC), which generally occurs in the form of multiple recurrent synchronized tumors. Affected patients are carriers of a germline mutation in the VHL tumor suppressor gene. Somatic mutations of this gene are also found in sporadic ccRCC and numerous pan-genomic studies have reported a dysregulation of microRNA (miRNA) expression in these sporadic tumors. In order to investigate the molecular mechanisms underlying the pathogenesis of VHL-associated ccRCC, particularly in the context of multiple tumors, the present study characterized the mRNA and miRNA transcriptome through an integrative analysis compared with sporadic renal tumors. In the present study, two series of ccRCC samples were used. The first set consisted of several samples from different tumors occurring in the same patient, for two independent patients affected with VHL disease. The second set consisted of 12 VHL-associated tumors and 22 sporadic ccRCC tumors compared with a pool of normal renal tissue. For each sample series, an expression analysis of miRNAs and mRNAs was conducted using microarrays. The results indicated that multiple tumors within the kidney of a patient with VHL disease featured a similar pattern of miRNA and gene expression. In addition, the expression levels of miRNA were able to distinguish VHL-associated tumors from sporadic ccRCC, and it was identified that 103 miRNAs and 2,474 genes were differentially expressed in the ccRCC series compared with in normal renal tissue. The majority of dysregulated genes were implicated in 'immunity' and 'metabolism' pathways. Taken together, these results allow a better understanding of the occurrence of ccRCC in patients with VHL disease, by providing insights into dysregulated miRNA and mRNA. In the set of patients with VHL disease, there were few differences in miRNA and mRNA expression, thus indicating a similar molecular evolution of these synchronous tumors and suggesting that the same molecular mechanisms underlie the pathogenesis of these hereditary tumors.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

Acceleration of Diabetic Wound Healing with PHD2- and miR-210-Targeting Oligonucleotides

In diabetes-associated chronic wounds, the normal response to hypoxia is impaired and many cellular processes involved in wound healing are hindered. Central to the hypoxia response is hypoxia-inducible factor-1α (HIF-1α), which activates multiple factors that enhance wound healing by promoting cellular motility and proliferation, new vessel formation, and re-epithelialization. Prolyl hydroxylase domain-containing protein 2 (PHD2) regulates HIF-1α activity by targeting it for degradation under normoxia. HIF-1α also upregulates microRNA miR-210, which in turn regulates proteins involved in cell cycle control, DNA repair, and mitochondrial respiration in ways that are antagonistic to wound repair. We have identified a highly potent short synthetic hairpin RNA (sshRNA) that inhibits expression of PHD2 and an antisense oligonucleotide (antimiR) that inhibits miR-210. Both oligonucleotides were chemically modified for improved biostability and to mitigate potential immunostimulatory effects. Using the sshRNA to silence PHD2 transcripts stabilizes HIF-1α and, in combination with the antimiR targeting miR-210, increases proliferation and migration of keratinocytes in vitro. To assess activity and delivery in an impaired wound healing model in diabetic mice, PHD2-targeting sshRNAs and miR-210 antimiRs both alone and in combination were formulated for local delivery to wounds using layer-by-layer (LbL) technology. LbL nanofabrication was applied to incorporate sshRNA into a thin polymer coating on a Tegaderm mesh. This coating gradually degrades under physiological conditions, releasing sshRNA and antimiR for sustained cellular uptake. Formulated treatments were applied directly to splinted full-thickness excisional wounds in db/db mice. Cellular uptake was confirmed using fluorescent sshRNA. Wounds treated with a single application of PHD2 sshRNA or antimiR-210 closed 4 days faster than untreated wounds, and wounds treated with both oligonucleotides closed on average 4.75 days faster. Markers for neovascularization and cell proliferation (CD31 and Ki67, respectively) were increased in the wound area following treatment, and vascular endothelial growth factor (VEGF) was increased in sshRNA-treated wounds. Our results suggest that silencing of PHD2 and miR-210 either together or separately by localized delivery of sshRNAs and antimiRs is a promising approach for the treatment of chronic wounds, with the potential for rapid clinical translation.

Neural stem cell therapies and hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury is a significant cause of morbidity and mortality in the adult as well as in the neonate. Extensive pre-clinical studies have shown promising therapeutic effects of neural stem cell-based treatments for hypoxic-ischemic brain injury. There are two major strategies of neural stem cell-based therapies: transplanting exogenous neural stem cells and boosting self-repair of endogenous neural stem cells. Neural stem cell transplantation has been proved to improve functional recovery after brain injury through multiple by-stander mechanisms (e.g., neuroprotection, immunomodulation), rather than simple cell-replacement. Endogenous neural stem cells reside in certain neurogenic niches of the brain and response to brain injury. Many molecules (e.g., neurotrophic factors) can stimulate or enhance proliferation and differentiation of endogenous neural stem cells after injury. In this review, we first present an overview of neural stem cells during normal brain development and the effect of hypoxic-ischemic injury on the activation and function of endogenous neural stem cells in the brain. We then summarize and discuss the current knowledge of strategies and mechanisms for neural stem cell-based therapies on brain hypoxic-ischemic injury, including neonatal hypoxic-ischemic brain injury and adult ischemic stroke.

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.

Promise of chemokine network-targeted nanoparticles in combination nucleic acid therapies of metastatic cancer

Chemokines and chemokine receptors play key roles in cancer progression and metastasis. Although multiple chemokines and chemokine receptors have been investigated, inhibition of CXCR4 emerged as one of the most promising approaches in combination cancer therapy, especially when focused on the metastatic disease. Small RNA molecules, such as small interfering RNA (siRNA) and microRNA (miRNA), represent new class of therapeutics for cancer treatment through RNA interference-mediated gene silencing. However, the clinical applicability of siRNA and miRNA is severely limited by the lack of effective delivery systems. There is a significant therapeutic potential for CXCR4-targeted nanomedicines in combination with the delivery of siRNA and miRNA in cancer. Recently developed CXCR4-targeted polymeric drugs and nanomedicines, including cyclam- and chloroquine-based polymeric CXCR4 antagonists are introduced here and their ability to deliver functional siRNA and miRNA is discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

MicroRNA-210 aggravates hypoxia-induced injury in cardiomyocyte H9c2 cells by targeting CXCR4

BACKGROUND

Myocardial infarction (MI), a leading cause of mortality, is identified as the myocardial necrosis due to prolonged ischemia. Hypoxia, resulting from ischemia, induces cell apoptosis during MI. Since miR-210 is a hypoxia inducible factor, we aimed to explore the functional role of miR-210 in hypoxic H9c2 cells.

METHODS

Hypoxia-induced cell injury was evaluated according to cell viability, apoptosis and expression of apoptosis-associated proteins. miR-210 expression after hypoxia was tested. Then, miR-210 was overexpressed or silenced, and its effects on viability and apoptosis of H9c2 cells under normoxia and hypoxia were measured. Utilizing bioinformatics method, possible target genes of miR-210 were screened, and the interaction between miR-210 and target gene was investigated. Moreover, the effect of co-transfections with microRNAs and small interfering RNAs on hypoxia-induced cell injury as well as the possible involved signaling pathways was also determined.

RESULTS

Hypoxia induced cell injury and up-regulation of miR-210 in H9c2 cells. Hypoxia-induced cell injury was aggravated by miR-210 overexpression but was attenuated by miR-210 suppression. CXC chemokine receptor 4 (CXCR4) was a target gene of miR-210, and CXCR4 inhibition could reverse the effects of miR-210 inhibition on H9c2 cells. Furthermore, the key kinases involved in the SMAD and mTOR signaling pathways were down-regulated by hypoxia, and the down-regulations were reversed by miR-210 suppression through modulating CXCR4.

CONCLUSION

miR-210 was up-regulated in hypoxic H9c2 cells. Suppression of miR-210 attenuated hypoxia-induced cell injury in H9c2 cells by targeting CXCR4, along with activations of the SMAD and mTOR signaling pathways.

Specific circulating microRNAs display dose-dependent responses to variable intensity and duration of endurance exercise

Circulating microRNAs (c-miRNAs), plasma-based noncoding RNAs that control posttranscriptional gene expression, mediate processes that underlie phenotypical plasticity to exercise. The relationship and biological relevance between c-miRNA expression and variable dose exercise exposure remains uncertain. We hypothesized that certain c-miRNAs respond to changes in exercise intensity and/or duration in a dose-dependent fashion. Muscle release of such c-miRNAs may then deplete intracellular stores, thus facilitating gene reprogramming and exercise adaptation. To address these hypotheses, healthy men participated in variable intensity ( n = 12, 30 × 1 min at 6, 7, and 8 miles/h, order randomized) and variable duration ( n = 14, 7 × 1 mile/h for 30, 60, and 90 min, order randomized) treadmill-running protocols. Muscle-enriched c-miRNAs (i.e., miRNA-1 and miRNA-133a) and others with known relevance to exercise were measured before and after exercise. c-miRNA responses followed three profiles: 1) nonresponsive (miRNA-21 and miRNA-210), 2) responsive to exercise at some threshold but without dose dependence (miRNA-24 and miRNA-146a), and 3) responsive to exercise with dose dependence to increasing intensity (miRNA-1) or duration (miRNA-133a and miRNA-222). We also studied aerobic exercise-trained mice, comparing control, low-intensity (0.5 km/h), or high-intensity (1 km/h) treadmill-running protocols over 4 wk. In high- but not low-intensity-trained mice, we found increased plasma c-miR-133a along with decreased intracellular miRNA-133a and increased serum response factor, a known miR-133a target gene, in muscle. Characterization of c-miRNAs that are dose responsive to exercise in humans and mice supports the notion that they directly mediate physiological adaptation to exercise, potentially through depletion of intracellular stores of muscle-specific miRNAs. NEW & NOTEWORTHY In this study of humans and mice, we define circulating microRNAs in plasma that are dose responsive to exercise. Our data support the notion that these microRNAs mediate physiological adaptation to exercise potentially through depletion of intracellular stores of muscle-specific microRNAs and releasing their inhibitory effects on target gene expression.

miR-210 and GPD1L regulate EDN2 in primary and immortalized human granulosa-lutein cells

Endothelin-2 (EDN2), expressed at a narrow window during the periovulatory period, critically affects ovulation and corpus luteum (CL) formation. LH (acting mainly via cAMP) and hypoxia are implicated in CL formation; therefore, we aimed to elucidate how these signals regulate EDN2 using human primary (hGLCs) and immortalized (SVOG) granulosa-lutein cells. The hypoxiamiR, microRNA-210 (miR-210) was identified as a new essential player in EDN2 expression. Hypoxia (either mimetic compound-CoCl₂, or low O₂) elevated hypoxia-inducible factor 1A (HIF1A), miR-210 and EDN2 Hypoxia-induced miR-210 was suppressed in HIF1A-silenced SVOG cells, suggesting that miR-210 is HIF1A dependent. Elevated miR-210 levels in hypoxia or by miR-210 overexpression, increased EDN2 Conversely, miR-210 inhibition reduced EDN2 levels, even in the presence of CoCl₂, indicating the importance of miR-210 in the hypoxic induction of EDN2 A molecule that destabilizes HIF1A protein, glycerol-3-phosphate dehydrogenase 1-like gene-GPD1L, was established as a miR-210 target in both cell types. It was decreased by miR-210-mimic and was increased by miR-inhibitor. Furthermore, reducing GPD1L by endogenously elevated miR-210 (in hypoxia), miR-210-mimic or by GPD1L siRNA resulted in elevated HIF1A protein and EDN2 levels, implying a vital role for GPD1L in the hypoxic induction of EDN2 Under normoxic conditions, forskolin (adenylyl cyclase activator) triggered changes typical of hypoxia. It elevated HIF1A, EDN2 and miR-210 while inhibiting GPD1L Furthermore, HIF1A silencing greatly reduced forskolin's ability to elevate EDN2 and miR-210. This study highlights the novel regulatory roles of miR-210 and its gene target, GPD1L, in hypoxia and cAMP-induced EDN2 by human granulosa-lutein cells.

Synthesis and Evaluation of Chloroquine-Containing DMAEMA Copolymers as Efficient Anti-miRNA Delivery Vectors with Improved Endosomal Escape and Antimigratory Activity in Cancer Cells

Chloroquine-containing 2-(dimethylamino)ethyl methacrylate copolymers (PDCs) are synthesized by reversible addition-fragmentation chain-transfer polymerization. Systematic evaluation is performed to test the hypothesis that presence of chloroquine (CQ) in the PDC structure will improve miRNA delivery due to enhanced endosomal escape while simultaneously contribute to anticancer activity of PDC/miRNA polyplexes through inhibition of cancer cell migration. The results show that miRNA delivery efficiency is dependent both on the molecular weight and CQ. The best performing PDC/miRNA polyplexes show effective endosomal escape of miRNA. PDC polyplexes with therapeutic miR-210 show promising anticancer activity in human breast cancer cells. PDC/miRNA polyplexes show excellent ability to inhibit migration of cancer cells. Overall, this study supports the use of PDC as a promising polymeric drug platform for use in combination anti-metastatic and anticancer miRNA therapeutic strategies.

Epigenetic Regulation of Vascular Aging and Age-Related Vascular Diseases

Vascular aging refers to the structural and functional defects that occur in the aorta during the aging process and is characterized by increased vascular cell senescence, vascular dyshomeostasis, and vascular remodeling. Vascular aging is a major risk factor for vascular diseases. However, the current understanding of the biological process of vascular aging and age-related diseases is insufficient. Epigenetic regulation can influence gene expression independently of the gene sequence and mainly includes DNA methylation, histone modifications, and RNA-based gene regulation. Epigenetic regulation plays important roles in many physiological and pathophysiological processes and may explain some gaps in our knowledge regarding the interaction between genes and diseases. In this review, we summarize recent advances in the understanding of the epigenetic regulation of vascular aging and age-related diseases in terms of vascular cell senescence, vascular dyshomeostasis, and vascular remodeling. Moreover, the possibility of targeting epigenetic regulation to delay vascular aging and treat age-related vascular diseases is also discussed.

Endothelial dysfunction in pulmonary arterial hypertension: an evolving landscape (2017 Grover Conference Series)

Endothelial dysfunction is a major player in the development and progression of vascular pathology in pulmonary arterial hypertension (PAH), a disease associated with small vessel loss and obstructive vasculopathy that leads to increased pulmonary vascular resistance, subsequent right heart failure, and premature death. Over the past ten years, there has been tremendous progress in our understanding of pulmonary endothelial biology as it pertains to the genetic and molecular mechanisms that orchestrate the endothelial response to direct or indirect injury, and how their dysregulation can contribute to the pathogenesis of PAH. As one of the major topics included in the 2017 Grover Conference Series, discussion centered on recent developments in four areas of pulmonary endothelial biology: (1) angiogenesis; (2) endothelial-mesenchymal transition (EndMT); (3) epigenetics; and (4) biology of voltage-gated ion channels. The present review will summarize the content of these discussions and provide a perspective on the most promising aspects of endothelial dysfunction that may be amenable for therapeutic development.

MicroRNA-191, regulated by HIF-2α, is involved in EMT and acquisition of a stem cell-like phenotype in arsenite-transformed human liver epithelial cells

Inorganic arsenic is widely distributed in the environment, and epidemiologic data show a strong association between arsenic exposure and risk of liver cancer. An understanding of the mechanisms underlying development of liver cancer and metastasis would be useful in reducing the incidence and mortality of liver cancer. MicroRNAs (miRs) act as regulators in liver cancer. Here, we show that acute or chronic exposure of human liver epithelial L-02 cells to arsenite increased expression of miR-191. There were decreased levels of BASP-1 and E-cadherin and increased levels of WT-1 and N-cadherin, indicating that arsenite induced epithelial-mesenchymal transition (EMT). Moreover, arsenite increased EpCAM and CD90 mRNA levels, showing the acquisition of stem cell-like properties by these cells. Suppression of miR-191 resulted in repression of EMT and reduced expression of stem-cell markers. Further, a miR-191 inhibitor blocked spheroid formation and production of side population cells. Luciferase reporter assays indicated that miR-191 was a target of HIF-2α, and inhibition of miR-191 decreased the neoplastic and metastatic properties of arsenite-transformed L-02 cells. Thus, in arsenite-transformed liver epithelial cells, transcriptional activation of the miR-191 promoter by HIF-2α is involved in EMT and in the acquisition of a stem cell-like phenotype.

Antioxidant responses and deregulation of epigenetic writers and erasers link oxidative stress and DNA methylation in bovine blastocysts

Early mammalian embryos derived from in vitro fertilization are exposed to conditions distinct from the native oviduct-uterine environment, including atmospheric oxygen that promotes cellular oxidative stress and alters gene expression. High oxygen partial pressure during embryo development is associated with low pregnancy rates and increased embryonic apoptosis. We investigated how bovine embryos responded to high (20%) or low (5%) oxygen partial pressure during in vitro culture, evaluating levels of reactive oxygen species (ROS) as well as changes in the expression of oxidative stress- and epigenetic-related transcripts and miRNAs in blastocysts. Additionally, we determined the global DNA methylation levels in the resulting embryos. Our data indicated that bovine blastocysts produced in vitro under high oxygen partial pressure possessed elevated ROS abundance and exhibited increased expression of CAT, GLRX2, KEAP1, NFR2, PRDX1, PRDX3, SOD1, TXN, and TXNRD1, versus reduced levels of the oxidative stress-related bta-miR-210. These stressed embryos also presented altered expression of the epigenetic-associated transcripts DNMT3A, H2AFZ, H3F3B, HDAC2, MORF4L2, REST, and PAF1. In addition, we demonstrated that embryos cultured under high oxygen partial pressure have increased global DNA methylation, suggesting that DNA hypermethylation is mediated by the deregulation of epigenetic-related enzymes due to oxidative stress.

Inhibition of microRNA-210 suppresses pro-inflammatory response and reduces acute brain injury of ischemic stroke in mice

Stroke is a leading cause of mortality and chronic neurologic disability. Yet, the successful treatment remains limited. In this study, we investigated the efficacy and the mechanism of a novel treatment, microRNA-210 (miR-210) inhibition, in protecting acute ischemic brain injury in adult mice. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in adult male C57BL/6 mice. MiR-210-LNA (miR-210 inhibitor) or the negative control was administered via intracerebroventricular injection 24h prior or 4h after MCAO. Cerebral infarction volume and behavioral deficits were determined 48h after MCAO. The expression of inflammation-related genes and infiltration/activation of various immune cells in the brain were assessed by RT-qPCR, flow cytometry, and immunohistochemistry. Acute ischemic stroke significantly increased miR-210 levels in the brain, which was abolished by miR-210-LNA administered prior to MCAO. Pre- and post-MCAO treatments with miR-210-LNA significantly decreased cerebral infarction and ameliorated behavioral deficits induced by MCAO. Long-term behavioral recovery was also improved by miR-210-LNA post-treatment. At the same time, inhibition of miR-210 significantly reduced the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and chemokines (CCL2 and CCL3), but had no significant effect on anti-inflammatory factors (TGF-β and IL-10). In addition, MCAO-induced macrophage infiltration and microglial activation in the brain were inhibited by the miR-210-LNA treatment. In summary, inhibition of miR-210 suppresses pro-inflammatory response and reduces brain damage in the acute phase of ischemic stroke, providing new insight in molecular basis of a novel therapeutic strategy of miR-210 inhibition in the treatment of acute ischemic stroke.

Low miR-210 and CASP8AP2 expression is associated with a poor outcome in pediatric acute lymphoblastic leukemia

The prognostic significance of microRNA (miR)-210 and the caspase 8-associated protein 2 (CASP8AP2) gene in children with acute lymphoblastic leukemia (ALL) has been validated and CASP8AP2 has been demonstrated as a target of miR-210. In the present study, the reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to determine miR-210 and CASP8AP2 expression in 91 children with ALL. Associations between gene expression levels and the prognostic value of combined detection of the two indicators were analyzed. Results from a receiver operating characteristic curve demonstrated that threshold values of miR-210 and CASP8AP2 were 3.8243 and 0.4760, respectively. Although the expression of miR-210 and CASP8AP2 were not associated at the mRNA level in pediatric ALL, combined detection of the two predicted ALL prognosis with an increased accuracy. Furthermore, an equation was devised including minimal residual disease at day 33 and expression of miR-210 and CASP8AP2, which may enable bone marrow relapse to be predicted more precisely compared with the current risk stratification.

Plasmatic miR-210, miR-221 and miR-1233 profile: potential liquid biopsies candidates for renal cell carcinoma

Renal cell carcinoma (RCC) represents a challenge for clinicians since the nonexistence of screening and monitoring tests contributes to the fact that one-third of patients are diagnosed with metastatic disease and 20–40% of the remaining patients will also develop metastasis. Modern medicine is now trying to establish circulating biomolecules as the gold standard of biomarkers. Among the molecules that can be released from tumor cells we can find microRNAs. The aim of this study was to evaluate the applicability of cancer-related miR-210, miR-218, miR-221 and miR-1233 as prognostic biomarkers for RCC. Patients with higher levels of miR-210, miR-221 and miR-1233 presented a higher risk of specific death by RCC and a lower cancer-specific survival. The addition of miR-210, miR-221 and miR-1233 plasma levels information improved the capacity to predict death by cancer in 8, 4% when compared to the current variables used by clinicians. We also verified that hypoxia stimulates the release of miR-210 and miR-1233 from HKC-8, RCC-FG2 and 786-O cell lines. These results support the addition of circulating microRNAs as prognostic biomarkers for RCC.

Various levels of circulating exosomal total-miRNA and miR-210 hypoxamiR in different forms of pregnancy hypertension

INTRODUCTION

Hypertension is a common complication during pregnancy, affecting 10% of pregnant women worldwide. Several microRNA (miRNA) were shown to be involved in hypertensive disorders of pregnancy. In preeclampsia (PE), placental dysfunction causes the enhanced release of extracellular vesicle-derived miRNAs. The hypoxia-sensitive hsa-mir-210 is the most common PE-associated miRNA, but its exosomal profile has not been investigated.

OBJECTIVES

Our aims were to measure exosomal total-miRNA concentration and to perform expression analysis of circulating exosomal hsa-miR-210 in women affected by chronic hypertension (CHT) gestational hypertension (GHT) or PE.

MATERIALS AND METHODS

We collected plasma samples from women with CHT, GHT, PE (moderate: mPE and severe: sPE) and from normotensive pregnancies. Exosomal miRNAs were extracted and miRNA concentration was measured. RT-PCR was carried out with hsa-miR-210-3p-specific primers and relative expression was calculated using the comparative Ct method.

RESULTS

The total-miRNA concentration was different in the disease subgroups, and was significantly higher in mPE and sPE compared to the other groups. We found a significant difference in the relative exosomal hsa-miR-210-3p expression between all hypertensive groups compared to the normotensive samples, but significant upregulation was only observed in case of mPE and sPE patients. Both the level of total-miRNA and hsa-miR-210 expression was higher in case of severe PE.

CONCLUSIONS

The level of circulating exosomal total-miRNA and hsa-miR-210 was elevated in women with PE, and it was higher in the severe form. We showed that hsa-miR-210 is secreted via exosomes, which may have a role in the pathomechanism of the disease.

The EGLN-HIF O2-Sensing System: Multiple Inputs and Feedbacks

The EGLN (also called PHD) prolyl hydroxylase enzymes and their canonical targets, the HIFα subunits, represent the core of an ancient oxygen-monitoring machinery used by metazoans. In this review, we highlight recent progress in understanding the overlapping versus specific roles of EGLN enzymes and HIF isoforms and discuss how feedback loops based on recently identified noncoding RNAs introduce additional layers of complexity to the hypoxic response. Based on novel interactions identified upstream and downstream of EGLNs, an integrated network connecting oxygen-sensing functions to metabolic and signaling pathways is gradually emerging with broad therapeutic implications.