Regulation and function of miRNA-21 in health and disease

miR-9-5p suppresses pro-fibrogenic transformation of fibroblasts and prevents organ fibrosis by targeting NOX4 and TGFBR2

Uncontrolled extracellular matrix (ECM) production by fibroblasts in response to injury contributes to fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Reactive oxygen species (ROS) generation is involved in the pathogenesis of IPF. Transforming growth factor-β1 (TGF-β1) stimulates the production of NADPH oxidase 4 (NOX4)-dependent ROS, promoting lung fibrosis (LF). Dysregulation of microRNAs (miRNAs) has been shown to contribute to LF. To identify miRNAs involved in redox regulation relevant for IPF, we performed arrays in human lung fibroblasts exposed to ROS. miR-9-5p was selected as the best candidate and we demonstrate its inhibitory effect on TGF-β receptor type II (TGFBR2) and NOX4 expression. Increased expression of miR-9-5p abrogates TGF-β1-dependent myofibroblast phenotypic transformation. In the mouse model of bleomycin-induced LF, miR-9-5p dramatically reduces fibrogenesis and inhibition of miR-9-5p and prevents its anti-fibrotic effect both in vitro and in vivo. In lung specimens from patients with IPF, high levels of miR-9-5p are found. In omentum-derived mesothelial cells (MCs) from patients subjected to peritoneal dialysis (PD), miR-9-5p also inhibits mesothelial to myofibroblast transformation. We propose that TGF-β1 induces miR-9-5p expression as a self-limiting homeostatic response.

Facts and updates about cardiovascular non-coding RNAs in heart failure

About 11% of all deaths include heart failure as a contributing cause. The annual cost of heart failure amounts to US $34,000,000,000 in the United States alone. With the exception of heart transplantation, there is no curative therapy available. Only occasionally there are new areas in science that develop into completely new research fields. The topic on non-coding RNAs, including microRNAs, long non-coding RNAs, and circular RNAs, is such a field. In this short review, we will discuss the latest developments about non-coding RNAs in cardiovascular disease. MicroRNAs are short regulatory non-coding endogenous RNA species that are involved in virtually all cellular processes. Long non-coding RNAs also regulate gene and protein levels; however, by much more complicated and diverse mechanisms. In general, non-coding RNAs have been shown to be of great value as therapeutic targets in adverse cardiac remodelling and also as diagnostic and prognostic biomarkers for heart failure. In the future, non-coding RNA-based therapeutics are likely to enter the clinical reality offering a new treatment approach of heart failure.

[MicroRNAs in kidney fibrosis]

Renal fibrosis represents the final stage of most chronic kidney diseases and contributes to the progressive and irreversible decline in kidney function with accumulation of extracellular matrix components in the renal parenchyma. The molecular mechanisms governing the renal fibrosis process are complex and remain poorly understood. Recently, the profibrotic role of several microRNAs (miRNAs) has been described in kidney fibrosis. MiRNAs are a new class of, small non-coding RNAs of about 20 nucleotides that act as gene expression negative regulators at the post-transcriptional level. Seminal studies have highlighted the potential importance of miRNA as new therapeutic targets and innovative diagnostic and/or prognostic biomarkers. This review summarizes recent scientific advances on the role played by miRNAs in kidney fibrogenesis and discusses potential clinical applications as well as future research directions.

Kallistatin inhibits TGF-β-induced endothelial-mesenchymal transition by differential regulation of microRNA-21 and eNOS expression

Kallistatin, an endogenous protein, consists of two structural elements: active site and heparin-binding domain. Kallistatin exerts beneficial effects on fibrosis by suppressing transforming growth factor (TGF)-β synthesis in animal models. TGF-β is the most potent inducer of endothelial-mesenchymal transition (EndMT), which contributes to fibrosis and cancer. MicroRNA (miR)-21 is an important player in organ fibrosis and tumor invasion. Here we investigated the potential role of kallistatin in EndMT via modulation of miR-21 in endothelial cells. Human kallistatin treatment blocked TGF-β-induced EndMT, as evidenced by morphological changes as well as increased endothelial and reduced mesenchymal marker expression. Kallistatin also inhibited TGF-β-mediated reactive oxygen species (ROS) formation and NADPH oxidase expression and activity. Moreover, kallistatin antagonized TGF-β-induced miR-21 and Snail1 synthesis, Akt phosphorylation, NF-κB activation, and matrix metalloproteinase 2 (MMP2) synthesis and activation. Kallistatin via its heparin-binding site blocked TGF-β-induced miR-21, Snail1 expression, and ROS formation, as wild-type kallistatin, but not heparin-binding site mutant kallistatin, exerted the effect. Conversely, kallistatin through its active site stimulated the synthesis of endothelial nitric oxide synthase (eNOS), sirtuin 1 (Sirt1) and forkhead box O1 (FoxO1); however, these effects were blocked by genistein, a tyrosine kinase inhibitor. This is the first study to demonstrate that kallistatin's heparin-binding site is crucial for preventing TGF-β-induced miR-21 and oxidative stress, while its active site is key for stimulating the expression of antioxidant genes via interaction with an endothelial surface tyrosine kinase. These findings reveal novel mechanisms of kallistatin in protection against fibrosis and cancer by suppressing EndMT.

"Pocket-sized RNA-Seq": A Method to Capture New Mature microRNA Produced from a Genomic Region of Interest

Currently, the discovery of new small ncRNAs requires high throughput methods even in the case of focused research on the regulation of specific genes or set of genes. We propose herein a simple, rapid, efficient, and cost effective method to clone and sequence single, yet unknown, small ncRNA. This technique that we called “Pocket-sized RNA-Seq” or psRNA-seq is based on in vitro transcription, RNA pull down and adapted RACE-PCR methods that allow its implementation using either available commercial kits or in-house reagents.

Salivary MicroRNA in Pancreatic Cancer Patients

Background

Pancreatic cancer is the fourth leading cause of cancer death in Western countries, with the lowest 1-year survival rate among commonly diagnosed cancers. Reliable biomarkers for pancreatic cancer diagnosis are lacking and are urgently needed to allow for curative surgery. As microRNA (miRNA) recently emerged as candidate biomarkers for this disease, we explored in the present pilot study the differences in salivary microRNA profiles between patients with pancreatic tumors that are not eligible for surgery, precancerous lesions, inflammatory disease or cancer-free patients as a potential early diagnostic tool.

Methods

Whole saliva samples from patients with pancreatic cancer (n = 7), pancreatitis (n = 4), IPMN (n = 2), or healthy controls (n = 4) were obtained during endoscopic examination. After total RNA isolation, expression of 94 candidate miRNAs was screened by q(RT)PCR using Biomark Fluidgm. Human-derived pancreatic cancer cells were xenografted in athymic mice as an experimental model of pancreatic cancer.

Results

We identified hsa-miR-21, hsa-miR-23a, hsa-miR-23b and miR-29c as being significantly upregulated in saliva of pancreatic cancer patients compared to control, showing sensitivities of 71.4%, 85.7%, 85,7% and 57%, respectively and excellent specificity (100%). Interestingly, hsa-miR-23a and hsa-miR23b are overexpressed in the saliva of patients with pancreatic cancer precursor lesions. We found that hsa-miR-210 and let-7c are overexpressed in the saliva of patients with pancreatitis as compared to the control group, with sensitivity of 100% and 75%, and specificity of 100% and 80%, respectively. Last hsa-miR-216 was upregulated in cancer patients as compared to patients diagnosed with pancreatitis, with sensitivity of 50% and specificity of 100%. In experimental models of PDAC, salivary microRNA detection precedes systemic detection of cancer cells markers.

Conclusions

Our novel findings indicate that salivary miRNA are discriminatory in pancreatic cancer patients that are not eligible for surgery. In addition, we demonstrate in experimental models that salivary miRNA detection precedes systemic detection of cancer cells markers. This study stems for the use of salivary miRNA as biomarker for the early diagnosis of patients with unresectable pancreatic cancer.

Inflammation-associated microRNA-130b down-regulates cytochrome P450 activities and directly targets CYP2C9

Expression of genes involved in absorption, distribution, metabolism, and excretion (ADME) of drugs is impaired in pathophysiologic conditions such as cholestasis and inflammation. The mechanisms of ADME gene down-regulation remain unclear. In our previous study, strongly elevated levels of microRNAs (miRNA) miR-21, miR-34a, and miR-130b in cholestatic liver and of miR-21 and miR-130b during inflammation were observed. Using HepaRG cells, which retain many functional characteristics of human hepatocytes, we investigated the potential of these miRNAs to down-regulate ADME genes. Cells were transfected with the corresponding miRNA mimics, chemically modified double-stranded RNAs that mimic endogenous miRNAs, followed by mRNA profiling by quantitative reverse-transcription polymerase chain reaction. Activities of six cytochrome P450 enzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP3A4) were determined with a liquid chromatography with tandem mass spectrometric cocktail assay. Although miR-21 and miR-34a showed few effects, transfection of miR-130b led to significantly lower expression of nuclear receptors constitutive androstane receptor (CAR) and farnesoid X receptor (FXRα), the CYPs 1A1, 1A2, 2A6, 2C8, 2C9, and 2C19, as well as GSTA2. Furthermore, miR-130b negatively affected activity levels of all measured P450s by at least 30%. Reporter gene assays employing the CYP2C9 3'-untranslated region (3'-UTR) confirmed direct regulation by miR-130b. These data support miR-130b as a potential negative regulator of drug metabolism by directly and/or indirectly affecting the expression of several ADME genes. This may be of relevance in pathophysiologic conditions such as cholestasis and inflammation, which are associated with increased miR-130b expression.

Differential expression and clinical significance of three inflammation-related microRNAs in gangliogliomas

PURPOSE

miR21, miR146, and miR155 represent a trio of microRNAs which has been shown to play a key role in the regulation of immune and inflammatory responses. In the present study, we investigated the differential expression and clinical significance of these three miRNAs in glioneuronal tumors (gangliogliomas, GGs) which are characterized by prominent activation of the innate immune response.

METHODS

The expression levels of miR21, miR146, and miR155 were evaluated using Taqman PCR in 34 GGs, including 15 cases with sufficient amount of perilesional cortex. Their expression was correlated with the tumor features and the clinical history of epilepsy. In addition, in situ hybridization was used to evaluate their cellular distribution in both tumor and peritumoral cortex.

RESULTS

Increased expression of miR146a was observed in both tumor and peritumoral cortex compared to control samples. miR146a was detected in both neuronal and astroglial cells. Tumor and peritumoral miR146a expression was negatively correlated with frequency of seizures and the density of activated microglial cells. Neuronal and astroglial expression was observed for both miR21 and miR155 with increased expression of miR21 within the tumor and miR155 in the peritumoral region. Negative correlations were observed between the miRNA levels and the expression of putative targets within the astroglial component of the tumor.

CONCLUSION

We report a differential regulation of three miRNAs, known to be related to inflammation, in both tumor and peritumoral cortex of patients with GG. Moreover, our findings suggest a functional relationship between miR146a expression and epilepsy, either directly in epileptogenesis or as modulation of seizure activity.

Platelet miRNAs and cardiovascular diseases

Activated platelets play a critical role in the acute complications of atherosclerosis that cause life-threatening ischemic events at late stages of the disease. The miRNAs are a novel class of small, non-coding RNAs that play a significant role in both inflammatory and cardiovascular diseases. The miRNAs are known to be present in platelets and exert important regulatory functions. Here we systematically examine the genes that are regulated by platelet miRNAs (miRNA-223,miRNA-126,miRNA-21, miRNA-24 and miRNA-197) and the association with cardiovascular disease risks. Platelet-secreted miRNAs could be novel biomarkers associated with cardiovascular diseases.

The pluripotency factor NANOG promotes the formation of squamous cell carcinomas

NANOG is a key pluripotency factor in embryonic stem cells that is frequently expressed in squamous cell carcinomas (SCCs). However, a direct link between NANOG and SCCs remains to be established. Here, we show that inducible overexpression of NANOG in mouse skin epithelia favours the malignant conversion of skin papillomas induced by chemical carcinogenesis, leading to increased SCC formation. Gene expression analyses in pre-malignant skin indicate that NANOG induces genes associated to epithelial-mesenchymal transition (EMT). Some of these genes are directly activated by NANOG, including EMT-associated genes Zeb1, Zeb2, Twist1, Prrx1 and miR-21. Finally, endogenous NANOG binds to the promoters of theses genes in human SCC cells and, moreover, NANOG induces EMT features in primary keratinocytes. These results provide in vivo evidence for the oncogenic role of NANOG in squamous cell carcinomas.

Live Cell MicroRNA Imaging Using Cascade Hybridization Reaction

Recent advances in RNA research have posed new directives in biology and chemistry to uncover the complex roles of ribonucleic acids in cellular processes. Innovative techniques to visualize native RNAs, particularly, short, low-abundance RNAs in live cells, can dramatically impact current research on the roles of RNAs in biology. Herein, we report a novel method for real-time, microRNA imaging inside live cells based on programmable oligonucleotide probes, which self-assemble through the Cascade Hybridization Reaction (CHR).

Impact of maternal obesity on fetal programming of cardiovascular disease

The in utero environment is a key determinant of long-term health outcomes; poor maternal metabolic state and placental insufficiency are strongly associated with these long-term health risks. Human epidemiological studies link maternal obesity and offspring cardiovascular disease in later life, but mechanistic studies in animal models are limited. Here, we review the literature pertaining to maternal consequences of obesity during pregnancy and the subsequent impact on fetal cardiovascular development.

Poor ovarian response in women undergoing in vitro fertilization is associated with altered microRNA expression in cumulus cells

OBJECTIVE

To analyze the association of micro-ribonucleic acid (miRNA) expression with the number of oocytes retrieved, in women undergoing in vitro fertilization (IVF).

DESIGN

Experimental study.

SETTING

Academic medical center.

PATIENT(S)

A total of 189 women undergoing IVF-intracytoplasmic sperm injection (ICSI).

INTERVENTION(S)

Pooled cumulus cells were collected.

MAIN OUTCOME MEASURE(S)

Poor responders were identified as patients who produced fewer oocytes than the 25th percentile of their respective age group. MicroRNAs were extracted from cumulus cells, and an miRNA microarray was performed, comparing poor responders (n = 3) to non-poor responders (n = 3). Expression of miR-21-5p (active strand of miR-21) and miR-21-3p was tested in poor responders (n = 21) and non-poor responders (n = 29), using reverse transcription real-time polymerase chain reaction (qRT-PCR). Regulation of miR-21-5p and miR-21-3p, in human granulosa-like tumor (KGN) cells, by estradiol (E2), was tested in vitro.

RESULT(S)

MicroRNA microarray analysis showed up-regulation of 16 miRNAs and down-regulation of 88 miRNAs in poor responders. Notably, miR-21 was significantly up-regulated 5-fold in poor-responder samples. Analysis using qRT-PCR confirmed that miR-21-5p expression was significantly up-regulated in poor responders, whereas miR-21-3p expression was significantly lower, suggesting that elevated miR-21-5p expression in cumulus cells is not regulated at the pre-miR-21 level in poor responders. Both miR-21-5p and miR-21-3p were increased in KGN cells in response to higher doses of E2; their expression was not affected at lower E2 concentrations.

CONCLUSION(S)

We found that poor response to IVF is associated with altered miRNA expression in cumulus cells, specifically with elevated expression of miR-21-5p, and that this elevated expression is independent of lower serum E2 levels in poor responders.

DUBs, the regulation of cell identity and disease

The post-translational modification of proteins with ubiquitin represents a complex signalling system that co-ordinates essential cellular functions, including proteolysis, DNA repair, receptor signalling and cell communication. DUBs (deubiquitinases), the enzymes that disassemble ubiquitin chains and remove ubiquitin from proteins, are central to this system. Reflecting the complexity and versatility of ubiquitin signalling, DUB activity is controlled in multiple ways. Although several lines of evidence indicate that aberrant DUB function may promote human disease, the underlying molecular mechanisms are often unclear. Notwithstanding, considerable interest in DUBs as potential drug targets has emerged over the past years. The future success of DUB-based therapy development will require connecting the basic science of DUB function and enzymology with drug discovery. In the present review, we discuss new insights into DUB activity regulation and their links to disease, focusing on the role of DUBs as regulators of cell identity and differentiation, and discuss their potential as emerging drug targets.

miR-21 Inhibition Reduces Liver Fibrosis and Prevents Tumor Development by Inducing Apoptosis of CD24+ Progenitor Cells

miR-21 is upregulated in hepatocellular carcinoma and intrahepatic cholangiocarcinoma, where it is associated with poor prognosis. Here, we offer preclinical evidence that miR-21 offers a therapeutic and chemopreventive target in these liver cancers. In mice with hepatic deletion of Pten, anti-miR-21 treatment reduced liver tumor growth and prevented tumor development. These effects were accompanied with a decrease in liver fibrosis and a concomitant reduction of CD24(+) liver progenitor cells and S100A4(+) cancer-associated stromal cells. Notch2 inhibition also occurred in tumors following anti-miR-21 treatment. We further showed that miR-21 is necessary for the survival of CD24(+) progenitor cells, a cellular phenotype mediated by Notch2, osteopontin, and integrin αv. Our results identify miR-21 as a key regulator of tumor-initiating cell survival, malignant development, and growth in liver cancer, highlighting the role of CD24(+) cells in the expansion of S100A4(+) cancer-associated stromal cells and associated liver fibrosis.

Gene expression in transformed lymphocytes reveals variation in endomembrane and HLA pathways modifying cystic fibrosis pulmonary phenotypes

Variation in cystic fibrosis (CF) phenotypes, including lung disease severity, age of onset of persistent Pseudomonas aeruginosa (P. aeruginosa) lung infection, and presence of meconium ileus (MI), has been partially explained by genome-wide association studies (GWASs). It is not expected that GWASs alone are sufficiently powered to uncover all heritable traits associated with CF phenotypic diversity. Therefore, we utilized gene expression association from lymphoblastoid cells lines from 754 p.Phe508del CF-affected homozygous individuals to identify genes and pathways. LPAR6, a G protein coupled receptor, associated with lung disease severity (false discovery rate q value = 0.0006). Additional pathway analyses, utilizing a stringent permutation-based approach, identified unique signals for all three phenotypes. Pathways associated with lung disease severity were annotated in three broad categories: (1) endomembrane function, containing p.Phe508del processing genes, providing evidence of the importance of p.Phe508del processing to explain lung phenotype variation; (2) HLA class I genes, extending previous GWAS findings in the HLA region; and (3) endoplasmic reticulum stress response genes. Expression pathways associated with lung disease were concordant for some endosome and HLA pathways, with pathways identified using GWAS associations from 1,978 CF-affected individuals. Pathways associated with age of onset of persistent P. aeruginosa infection were enriched for HLA class II genes, and those associated with MI were related to oxidative phosphorylation. Formal testing demonstrated that genes showing differential expression associated with lung disease severity were enriched for heritable genetic variation and expression quantitative traits. Gene expression provided a powerful tool to identify unrecognized heritable variation, complementing ongoing GWASs in this rare disease.

MicroRNAs in adrenal tumors: relevance for pathogenesis, diagnosis, and therapy

Several lines of evidence support the relevance of microRNAs in both adrenocortical and adrenomedullary (pheochromocytomas) tumors. Significantly differentially expressed microRNAs have been described among benign and malignant adrenocortical tumors and different forms of pheochromocytomas that might affect different pathogenic pathways. MicroRNAs can be exploited as markers of malignancy or disease recurrence. Besides tissue microRNAs, novel data show that microRNAs are released in body fluids, and blood-borne microRNAs can be envisaged as minimally invasive markers of malignancy or prognosis. MicroRNAs might even serve as treatment targets that could expand the rather-limited therapeutic repertoire in the field of adrenal tumors. In this review, we present a critical synopsis of the recent observations made in the field of adrenal tumor-associated microRNAs regarding their pathogenic, diagnostic, and potential therapeutic relevance.

Plasma microRNAs are associated with atrial fibrillation and change after catheter ablation (the miRhythm study)

BACKGROUND

MicroRNAs (miRNAs) are associated with cardiovascular disease and control gene expression and are detectable in the circulation.

OBJECTIVE

The purpose of this study was to test the hypothesis that circulating miRNAs may be associated with atrial fibrillation (AF).

METHODS

Using a prospective study design powered to detect subtle differences in miRNAs, we quantified plasma expression of 86 miRNAs by high-throughput quantitative reverse transcriptase-polymerase chain reaction in 112 participants with AF and 99 without AF. To examine parallels between cardiac and plasma miRNA profiles, we quantified atrial tissue and plasma miRNA expression using quantitative reverse transcriptase-polymerase chain reaction in 31 participants undergoing surgery. We also explored the hypothesis that lower AF burden after ablation would be reflected in the circulating blood pool by examining change in plasma miRNAs after AF ablation (n = 47).

RESULTS

Mean age of the cohort was 59 years; 58% of participants were men. Plasma miRs-21 and 150 were 2-fold lower in participants with AF than in those without AF after adjustment (P ≤.0006). Plasma levels of miRs-21 and 150 also were lower in participants with paroxysmal AF than in those with persistent AF (P <.05). Expression of miR-21, but not of miR-150, was lower in atrial tissue from patients with AF than in those without AF (P <.05). Plasma levels of miRs-21 and 150 increased 3-fold after AF ablation (P ≤.0006).

CONCLUSION

Cardiac miRs-21 and 150 are known to regulate genes implicated in atrial remodeling. Our findings show associations between plasma miRs-21 and 150 and AF, suggesting that circulating miRNAs can provide insights into cardiac gene regulation.

microRNA and Pain

Pain is an important protective system that alerts organisms to actual or possible tissue damage. However, a variety of pathologies can lead to chronic pain that is no longer beneficial. Lesions or diseases of the somatosensory nervous system cause intractable neuropathic pain that occasionally lasts even after the original pathology subsides. Chronic inflammatory diseases like arthritis are also associated with severe pain. Because conventional analgesics such as non-steroidal anti-inflammatory drugs and opioids have limited efficacy and/or severe adverse events associated with long-term use, chronic pain remains a major problem in clinical practice. Recently, causal roles of microRNAs in chronic pain and their therapeutic potential have been emerging. microRNA expressions are altered not only at the primary origin of pain, but also along the somatosensory pathways. Notably, microRNA expressions are differentially affected depending on the causes of chronic pain. This chapter summarizes current insights into the roles of microRNAs in pain based on the underlying pathologies.

A review: fabrications, detections and applications of peptide nucleic acids (PNAs) microarray

Peptide nucleic acid (PNA) is a mimic of DNA that shows a high chemical stability and can survive the enzymatic degradation of nucleases and proteases. The superior binding properties of PNA enable the formation of PNA/DNA or PNA/RNA duplex with excellent thermal stability and unique ionic strength effect. The introduction of microarray makes it possible to achieve accurate, high throughput parallel analysis of DNA or RNA with a highly integrated and low reagents consuming device. This powerful tool expands the applications of PNA in genotyping based on single nucleotide polymorphism (SNP) detection, the monitoring of disease-related miRNA expression and pathogen detection. This review paper discusses the fabrications of PNA microarrays through in situ synthesis strategy or spotting method by automatic devices, the various detection methods for the microarray-based hybridization and the current applications of PNA microarrays.

Small molecule chemical probes of microRNA function

MicroRNAs (miRNAs) are small, non-coding RNAs that control protein expression. Aberrant miRNA expression has been linked to various human diseases, and thus miRNAs have been explored as diagnostic markers and therapeutic targets. Although it is challenging to target RNA with small molecules in general, there have been successful campaigns that have identified small molecule modulators of miRNA function by targeting various pathways. For example, small molecules that modulate transcription and target nuclease processing sites in miRNA precursors have been identified. Herein, we describe challenges in developing chemical probes that target miRNAs and highlight aspects of miRNA cellular biology elucidated by using small molecule chemical probes. We expect that this area will expand dramatically in the near future as progress is made in understanding small molecule recognition of RNA.

Non-coding RNAs: biological functions and applications

Analyses of the international human genome sequencing results in 2004 converged to a consensual number of ~20,000 protein-coding genes, spanning over <2% of the total genomic sequence. Therefore, the developmental and physiological complexity of human beings remains unaccounted if viewed only in terms of the number of protein-coding genes; the epigenetic influences involving chromatin remodelling and RNA interference and alternative precursor messenger RNA splicing of functional protein-coding transcripts as well as post-translational modifications of proteins increase the diversity and the functionality of the proteome and likely explain the increased complexity. In addition, there has been an explosion of research addressing possible functional roles for the other 98% of the human genome that does not encode proteins. In fact, >90% of the human genome is likely to be transcribed yielding a complex network of overlapping transcripts that include tens of thousands of long RNAs with little or no protein forming capacity; they are collectively called non-coding RNA. This review highlights the fundamental concepts of biological roles of non-coding RNA and their importance in regulation of cellular physiology under disease conditions like cancer.

Prediction of long-term outcome after acute myocardial infarction using circulating miR-145

BACKGROUND

Recent reports have shown that miR-145 concentration correlates with infarct size. In this paper, we attempt to predict heart failure and cardiovascular death after acute myocardial infarction using circulating miR-145 concentration.

METHODS

We assessed 246 patients with first ST-segment-elevation myocardial infarction who underwent successful percutaneous coronary intervention. We measured circulating miR-145, N-terminal fragment of the precursor B-type natriuretic peptide, myocardial-band creatine kinase, and cardiac troponin-I concentrations on day 5 after primary percutaneous coronary intervention and assessed their correlations with long-term clinical outcome.

RESULTS

During the one-year follow-up period, 72 patients experienced primary composite cardiac events (cardiac death or hospitalization for worsening heart failure). Multivariable Cox proportional hazards analysis indicated that circulating miR-145 (hazard ratio 7.174, 95% confidence interval 4.208-12.229); p < 0.0001) was a significant independent predictor of cardiac events after adjustment for multiple confounders.

CONCLUSION

Circulating miR-145 may be a novel biomarker for predicting long-term outcome after acute myocardial infarction.

The clinical utility of microRNA-21 as novel biomarker for diagnosing human cancers

With cancer being a major cause of death worldwide, microRNAs (miRNAs) have been investigated as novel and non-invasive biomarkers for cancer diagnosis. Recently, microRNA-21 (miR-21) attracts much attention for its aberrant expression and has been widely studied in various cancers. However, the inconsistent results from studies make it hard to evaluate the diagnostic value of miR-21 in cancer diagnosis, which lead us to conduct this meta-analysis. We conducted a comprehensive literature search in the Medline, Embase, PubMed, CNKI, and Web of Science before July 1, 2014. STATA 12.0 software was used for calculation and statistical analysis. The pooled sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR), and diagnostic odds ratio (DOR) were used to assess the diagnostic performance of miR-21 for cancers. Seventy-three studies in 60 articles were involved in this meta-analysis, with a total of 4684 patients with cancer and 3108 controls. The overall parameters were calculated from all the included studies: sensitivity of 0.78 (95% confidence interval (CI) 0.74-0.81), specificity of 0.83 (95% CI 0.80-0.86), PLR of 4.5 (95% CI 3.8-5.4), NLR of 0.27 (95% CI 0.23-0.32); DOR of 17 (95% CI 12-23), and area under the curve (AUC) of 0.88 (95% CI 0.84-0.90). In addition, we performed subgroup analyses based on ethnicity, cancer types, and sample types. Results from subgroup analysis showed that cancer types and sample types were the sources of heterogeneity in our meta-analysis. The overall diagnostic value of miR-21 is not very high for cancer diagnosis; however, it is affected significantly by the types of cancer and specimen. MiR-21 has a relatively high diagnostic value for detecting breast cancer, and miR-21 assays based on plasma, serum, and tissue achieved relatively higher accuracy.

Voltage‑gated K+ channel blocker quinidine inhibits proliferation and induces apoptosis by regulating expression of microRNAs in human glioma U87‑MG cells

Accumulating evidence has proved that potassium channels (K+ channels) are involved in regulating cell proliferation, cell cycle progression and apoptosis of tumor cells. However, the precise cellular mechanisms are still unknown. In the present study, we investigated the effect and mechanisms of quinidine, a commonly used voltage-gated K+ channel blocker, on cell proliferation and apoptosis of human glioma U87-MG cells. We found that quinidine significantly inhibited the proliferation of U87-MG cells and induced apoptosis in a dose-dependent manner. The results of caspase colorimetric assay showed that the mitochondrial pathway was the main mode involved in the quinidine-induced apoptotic process. Furthermore, the concentration range of quinidine, which inhibited voltage-gated K+ channel currents in electrophysiological assay, was consistent with that of quinidine inhibiting cell proliferation and inducing cell apoptosis. In U87-MG cells treated with quinidine (100 µmol/l), 11 of 2,042 human microRNAs (miRNAs) were upregulated and 16 were downregulated as detected with the miRNA array analysis. The upregulation of miR-149-3p and downregulation of miR-424-5p by quinidine treatment were further verified by using quantitative real-time PCR. In addition, using miRNA target prediction program, putative target genes related to cell proliferation and apoptosis for two differentially expressed miRNAs were predicted. Taken together, these data suggested that the anti-proliferative and pro-apoptosis effect of voltage-gated K+ channel blocker quinidine in human glioma cells was mediated at least partly through regulating expression of miRNAs, and provided further support for the mechanisms of voltage-gated K+ channels in mediating cell proliferation and apoptosis.

Expression of miRNAs in non-small-cell lung carcinomas and their association with clinicopathological features

Lung cancer is recognized as a leading cause of cancer-related deaths worldwide. Over the past several years, evidence emerged that microRNAs (miRNAs), a class of small non-coding RNA molecules regulating gene expression at posttranscriptional level, play an important role in cell functioning, as well as in human diseases. Here, we analyzed expression of miR-15a/16, miR-21, miR-34a, miR-126, miR-128, and miR-210 at transcriptional level in 30 non-small-cell lung carcinoma (NSCLC) tumor tissues compared to the matched adjacent normal tissues and their correlation with clinicopathological features of the patients. Samples were collected from the NSCLC patients undergoing surgery before radiotherapeutic or chemotherapeutic treatment. Expression levels of miRNAs were assessed by TaqMan RT-PCR assay. The data obtained in this study were processed using REST 2009 and SPSS statistical software. The graphs were designed by GraphPad prism 5.0. In tumor samples, we found downregulation of miR-15a/16 (50/83.3%), miR-34a (83.3%), miR-126 (70%), and miR-128 (63.3%). At the same time, miR-21 and miR-210 were upregulated by 53.3 and 66.6% in cancer tissue versus matched adjacent normal tissues, respectively. No significant correlation was found between the expression levels of miR-15a/16, miR-21, miR-34a, miR-126, miR-128, and miR-210 and lymph node, tumor size, sex, and smoking. However, the study demonstrated a correlation between a change in expression of miR-15, miR-16, miR-34a, miR-126, and miR-210 compared to normal tissues and TNM staging (P < 0.05). Furthermore, miR-126 expression level was different in adenocarcinomas and squamous cell carcinoma (SCC) subtype (P < 0.1). Detailed analysis revealed significant change in expression of miR-15a/16, miR-34a, miR-126, and miR-210 in NSCLC tumor samples indicating involvement of these miRNAs in lung cancer pathogenesis. miR-210 demonstrated the most consistent increase in tumor tissues between different patients, suggesting its potential significance for NSCLC.

microRNA-21 mediates epithelial-mesenchymal transition of human hepatocytes via PTEN/Akt pathway

miR-21 has been shown to play fundamental role in diverse biological and pathological processes, including fibrotic diseases. In the present study, we investigated whether miR-21 regulated the fibrogenic epithelial-mesenchymal transition (EMT) in human hepatocytes QSG-7701 and explored underlying mechanisms. The results showed that treatment of QSG-7701 cells with pro-fibrogenic factor TGF-β1 resulted in increased expression of miR-21 and promoted fibrogenic EMT in hepatocytes. Downregulation of miR-21 expression by transfection of anti-miR-21 into QSG-7701 cells inhibited fibrogenic EMT induced by TGF-β1. Furthermore, overexpression of miR-21 alone also resulted in EMT-like transformation in QSG-7701 cells. TGF-β1 treatment resulted in decreased PTEN and increased Akt phosphorylation and anti-miR-21 abolished this effect. Overexpression of miR-21 in QSG-7701 cells also downregulated PTEN and upregulated Akt phosphralation. Inhibition of Akt signaling by specific inhibitor Akt inhibitor IV blocked TGF-β1 and miR-21-induced fibrogenic EMT. In summary, our results identify miR-21 as a key regulator of fibrogenic EMT in hepatocytes via PTEN/Akt pathway. Targeting miR-21 may provide a new therapeutic strategy against hepatic fibrosis.

Stromal expression of miR-21 identifies high-risk group in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype defined by the lack of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression. Expression of miR-21, an oncomiR, is frequently altered and may be distinctly expressed in the tumor stroma. Because tumor lesions are a complex mixture of cell types, we hypothesized that analysis of miR-21 expression at single-cell resolution could provide more accurate information to assess disease recurrence risk and BC-related death. We implemented a fully automated, tissue slide-based assay to detect miR-21 expression in 988 patients with BC. The miR-21(High) group exhibited shorter recurrence-free survival [hazard ratio (HR), 1.71; P < 0.001] and BC-specific survival (HR, 1.96; P < 0.001) in multivariate regression analyses. When tumor compartment and levels of miR-21 expression were considered, significant associations with poor clinical outcome were detected exclusively in tumor epithelia from estrogen receptor- and/or progesterone receptor-positive human epidermal growth factor receptor 2-negative cases [recurrence-free survival: HR, 3.67 (P = 0.006); BC-specific survival: HR, 5.13 (P = 0.002)] and in tumor stroma from TNBC cases [recurrence-free survival: HR, 2.59 (P = 0.013); BC-specific survival: HR, 3.37 (P = 0.003)]. These findings suggest that the context of altered miR-21 expression provides clinically relevant information. Importantly, miR-21 expression was predominantly up-regulated and potentially prognostic in the tumor stroma of TNBC.

Long-term inhibition of miR-21 leads to reduction of obesity in db/db mice

OBJECTIVE

To assess the effect of long-term pharmacological inhibition of miR-21 in a model of metabolic syndrome and obesity.

METHODS

Aged db/db mice were treated with locked nucleic acid-modified anti-miRs directed against miR-21 (LNA-21), control LNAs or PBS for 18 weeks. Cardiac function was assessed by echocardiography and the effect on body weight and white adipose tissue (WAT) was evaluated.

RESULTS

MiR-21 expression was efficiently inhibited in the heart and WAT with no apparent liver toxicity or deterioration of kidney function. MiR-21 inhibition had no effect on cardiac hypertrophy as well as systolic and diastolic cardiac functions. However, levels of cardiac collagen 1 were modestly reduced in LNA-21 treated mice. MiR-21 inhibition reduced body weight, as well as adipocyte size and serum triglycerides were significantly decreased. The miR-21 targets TGFβ-receptor 2 (TGFBR2) and phosphatase and tensin homolog (PTEN) were derepressed in WAT of LNA-21 treated mice and Sprouty1 and 2 were increased after miR-21 inhibition.

CONCLUSIONS

Long-term treatment with LNA-21 is safe and efficiently suppresses miR-21 expression. Cardiac function was not affected. LNA-21 treatment led to a significant weight loss and reduces adipocyte size as well as derepression of the targets TGFRB2, PTEN, and Sprouty1 and 2.

microRNA-21-induced dissociation of PDCD4 from rictor contributes to Akt-IKKβ-mTORC1 axis to regulate renal cancer cell invasion

Renal cancer metastasis may result from oncogenic forces that contribute to the primary tumor. We have recently identified microRNA-21 as an oncogenic driver of renal cancer cells. The mechanism by which miR-21 controls renal cancer cell invasion is poorly understood. We show that miR-21 directly downregulates the proapoptotic protein PDCD4 to increase migration and invasion of ACHN and 786-O renal cancer cells as a result of phosphorylation/activation of Akt and IKKβ, which activate NFκB-dependent transcription. Constitutively active (CA) Akt or CA IKKβ blocks PDCD4-mediated inhibition and restores renal cancer cell migration and invasion. PDCD4 inhibits mTORC1 activity, which was reversed by CA IKKβ. Moreover, CA mTORC1 restores cell migration and invasion inhibited by PDCD4 and dominant negative IKKβ. Moreover, PDCD4 negatively regulates mTORC2-dependent Akt phosphorylation upstream of this cascade. We show that PDCD4 forms a complex with rictor, an exclusive component of mTORC2, and that this complex formation is reduced in renal cancer cells due to increased miR-21 expression resulting in enhanced phosphorylation of Akt. Thus our results identify a previously unrecognized signaling node where high miR-21 levels reduce rictor-PDCD4 interaction to increase phosphorylation of Akt and contribute to metastatic fitness of renal cancer cells.

Krüppel-like factor 9 inhibits glioma cell proliferation and tumorigenicity via downregulation of miR-21

Krüppel-like factors (KLFs) are zinc finger-containing transcription factors that play key roles in the regulation of differentiation and development as well as biological processes central to the development of malignancies. Increasing evidence indicates that Krüppel-like factor 9 (KLF9) plays a critical role in regulating tumorigenesis. However, the biological role and molecular mechanism of KLF9 in glioma progression remain unclear. Herein, we found that KLF9 expression was strongly reduced in gliomas. Reduced KLF9 expression promoted glioma cell proliferation. Importantly, re-constitution of KLF9 expression inhibited glioma cell proliferation and tumor growth in vivo. Furthermore, we determined that KLF9 interacted with the miR-21 promoter, leading to suppression of miR-21 expression and cell cycle arrest. Taken together, our findings indicate a novel mechanism for KLF function in tumorigenesis and may also suggest new targets for clinical intervention in human cancer.

Disruption of microRNA-21 by TALEN leads to diminished cell transformation and increased expression of cell-environment interaction genes

MicroRNA-21 is dysregulated in many cancers and fibrotic diseases. Since miR-21 suppresses several tumor suppressor and anti-apoptotic genes, it is considered a cancer therapeutic target. Antisense oligonucleotides are commonly used to inhibit a miRNA; however, blocking miRNA function via an antagomir is temporary, often only achieves a partial knock-down, and may be complicated by off-target effects. Here, we used transcription activator-like effector nucleases (TALENs) to disrupt miR-21 in cancerous cells. Individual deletion clones were screened and isolated without drug selection. Sequencing and quantitative RT-PCR identified clones with no miR-21 expression. The loss of miR-21 led to subtle but global increases of mRNAs containing miR-21 target sequences. Cells without miR-21 became more sensitive to cisplatin and less transformed in culture and in mouse xenografts. In addition to the increase of PDCD4 and PTEN protein, mRNAs for COL4A1, JAG1, SERPINB5/Maspin, SMAD7, and TGFBI - all are miR-21 targets and involved in TGFβ and fibrosis regulation - were significantly upregulated in miR-21 knockout cells. Gene ontology and pathway analysis suggested that cell-environment interactions involving extracellular matrix can be an important miR-21 pathogenic mechanism. The study also demonstrates the value of using TALEN-mediated microRNA gene disruption in human pathobiological studies.

miR-21 is a negative modulator of T-cell activation

microRNAs (miRNAs) are a class of small non-coding RNAs acting as post-transcriptional regulators of gene expression and play fundamental roles in regulating immune response and autoimmunity. We show that memory T-lymphocytes express higher levels of miR-21 compared to naïve T-lymphocytes and that miR-21 expression is induced upon TCR engagement of naïve T-cells. We identify bona fide miR-21 targets by direct immuno-purification and profiling of AGO2-associated mRNAs in Jurkat cells over-expressing miR-21. Our analysis shows that, in T-lymphocytes, miR-21 targets genes are involved in signal transduction. Coherently, TCR signalling is dampened upon miR-21 over-expression in Jurkat cells, resulting in lower ERK phosphorylation, AP-1 activation and CD69 expression. Primary human lymphocytes in which we impaired miR-21 activity, display IFN-γ production enhancement and stronger activation in response to TCR engagement as assessed by CD69, OX40, CD25 and CD127 analysis. By intracellular staining of the endogenous protein in primary T-lymphocytes we validate three key regulators of lymphocyte activation as novel miR-21 targets. Our results highlight an unexpected function of miR-21 as a negative modulator of signal transduction downstream of TCR in T-lymphocytes.

The structure, function and evolution of proteins that bind DNA and RNA

Proteins that bind both DNA and RNA typify the ability of a single gene product to perform multiple functions. Such DNA- and RNA-binding proteins (DRBPs) have unique functional characteristics that stem from their specific structural features; these developed early in evolution and are widely conserved. Proteins that bind RNA have typically been considered as functionally distinct from proteins that bind DNA and studied independently. This practice is becoming outdated, in partly owing to the discovery of long non-coding RNAs (lncRNAs) that target DNA-binding proteins. Consequently, DRBPs were found to regulate many cellular processes, including transcription, translation, gene silencing, microRNA biogenesis and telomere maintenance.

Interplay between steroid signalling and microRNAs: implications for hormone-dependent cancers

Hormones are key drivers of cancer development. To date, interest has largely been focussed on the classical model of hormonal gene regulation, but there is increasing evidence for a role of hormone signalling pathways in post-translational regulation of gene expression. In particular, a complex and dynamic network of bi-directional interactions with microRNAs (miRs) at all stages of biogenesis and during target gene repression is emerging. miRs, which act mainly by negatively regulating gene expression through association with 3'-UTRs of mRNA species, are increasingly understood to be important in development, normal physiology and pathogenesis. Given recent demonstrations of altered miR profiles in a diverse range of cancers, their ability to function as oncogenes or tumour suppressors, and hormonal regulation of miRs, understanding mechanisms by which miRs are generated and regulated is vitally important. miRs are transcribed by RNA polymerase II and then processed in the nucleus by the Drosha-containing Microprocessor complex and in the cytoplasm by Dicer, before mature miRs are incorporated into the RNA-induced silencing complex. It is increasingly evident that multiple cellular signalling pathways converge upon the miR biogenesis cascade, adding further layers of regulatory complexity to modulate miR maturation. This review summarises recent advances in identification of novel components and regulators of the Microprocessor and Dicer complexes, with particular emphasis on the role of hormone signalling pathways in regulating their activity. Understanding hormone regulation of miR production and how this is perturbed in cancer are critical for the development of miR-based therapeutics and biomarkers.

miR-21 promotes the differentiation of hair follicle-derived neural crest stem cells into Schwann cells

Hair follicle-derived neural crest stem cells can be induced to differentiate into Schwann cells in vivo and in vitro. However, the underlying regulatory mechanism during cell differentiation remains poorly understood. This study isolated neural crest stem cells from human hair follicles and induced them to differentiate into Schwann cells. Quantitative RT-PCR showed that microRNA (miR)-21 expression was gradually increased during the differentiation of neural crest stem cells into Schwann cells. After transfection with the miR-21 agonist (agomir-21), the differentiation capacity of neural crest stem cells was enhanced. By contrast, after transfection with the miR-21 antagonist (antagomir-21), the differentiation capacity was attenuated. Further study results showed that SOX-2 was an effective target of miR-21. Without compromising SOX2 mRNA expression, miR-21 can down-regulate SOX protein expression by binding to the 3′-UTR of miR-21 mRNA. Knocking out the SOX2 gene from the neural crest stem cells significantly reversed the antagomir-21 inhibition of neural crest stem cells differentiating into Schwann cells. The results suggest that miR-21 expression was increased during the differentiation of neural crest stem cells into Schwann cells and miR-21 promoted the differentiation through down-regulating SOX protein expression by binding to the 3′-UTR of SOX2 mRNA.

An evolutionarily conserved interaction of tumor suppressor protein Pdcd4 with the poly(A)-binding protein contributes to translation suppression by Pdcd4

The tumor suppressor protein programmed cell death 4 (Pdcd4) has been implicated in the translational regulation of specific mRNAs, however, the identities of the natural Pdcd4 target mRNAs and the mechanisms by which Pdcd4 affects their translation are not well understood. Pdcd4 binds to the eukaryotic translation initiation factor eIF4A and inhibits its helicase activity, which has suggested that Pdcd4 suppresses translation initiation of mRNAs containing structured 5′-untranslated regions. Recent work has revealed a second inhibitory mechanism, which is eIF4A-independent and involves direct RNA-binding of Pdcd4 to the target mRNAs. We have now identified the poly(A)-binding protein (PABP) as a novel direct interaction partner of Pdcd4. The ability to interact with PABP is shared between human and Drosophila Pdcd4, indicating that it has been highly conserved during evolution. Mutants of Pdcd4 that have lost the ability to interact with PABP fail to stably associate with ribosomal complexes in sucrose density gradients and to suppress translation, as exemplified by c-myb mRNA. Overall, our work identifies PABP as a novel functionally relevant Pdcd4 interaction partner that contributes to the regulation of translation by Pdcd4.

Atherosclerosis-related circulating miRNAs as novel and sensitive predictors for acute myocardial infarction

BACKGROUND

The dysregulated expressions of circulating miRNAs have been detected in various cardiovascular diseases. In our previous experiments, the altered expressions of circulating miRNA-21-5p, miRNA-361-5p and miRNA-519e-5p were confirmed in patients with coronary atherosclerosis by miRNA microarrays. However, the expression levels of these circulating miRNAs in the early phase of acute myocardial infarction (AMI) are still unknown. In the present study, our aims were to examine the expressions of circulating miR-21-5p, miR-361-5p and miR-519e-5p in AMI patients, and assess their clinical applications for diagnosing and monitoring AMI.

RESULTS

Two different cohorts were enrolled in this study. The first cohort included 17 AMI patients and 28 healthy volunteers, and the second cohort included 9 AMI patients, 9 ischemic stroke patients, 8 patients with pulmonary embolism, and 12 healthy volunteers. Quantitative real-time PCR and ELISA assays were preformed to detect the concentrations of plasma miRNAs and cardiac troponin I (cTnI), respectively. The results showed that the plasma levels of miR-21-5p and miR-361-5p were significantly increased in AMI patients, whereas the concentration of circulating miR-519e-5p was reduced. Interestingly, the levels of these circulating miRNAs correlated with the concentrations of plasma cTnI. Receiver operating characteristic (ROC) analysis revealed that these three circulating miRNAs had considerable diagnostic accuracy for AMI with high values of area under ROC curve (AUC). Importantly, combining the three miRNAs significantly increased the diagnostic accuracy. Furthermore, cell experiments demonstrated that these plasma miRNAs may originate from injured cardiomyocytes induced by hypoxia. In addition, the levels of all the three circulating miRNAs in ischemic stroke (IS) and pulmonary embolism (PE) were elevated, whereas the decreased level of plasma miR-519e-5p was only detected in AMI. ROC analysis demonstrated that circulating miR-519e-5p may be a useful biomarker for distinguishing AMI from other ischemic diseases.

CONCLUSIONS

Circulating miRNAs may be novel and powerful biomarkers for AMI and they could be potential diagnostic tool for AMI.

Noncoding RNAs as novel biomarkers in prostate cancer

Prostate cancer (PCa) is the second most common diagnosed malignant disease in men worldwide. Although serum PSA test dramatically improved the early diagnosis of PCa, it also led to an overdiagnosis and as a consequence to an overtreatment of patients with an indolent disease. New biomarkers for diagnosis, prediction, and monitoring of the disease are needed. These biomarkers would enable the selection of patients with aggressive or progressive disease and, hence, would contribute to the implementation of individualized therapy of the cancer patient. Since the FDA approval of the long noncoding PCA3 RNA-based urine test for the diagnosis of PCa patients, many new noncoding RNAs (ncRNAs) associated with PCa have been discovered. According to their size and function, ncRNAs can be divided into small and long ncRNAs. NcRNAs are expressed in (tumor) tissue, but many are also found in circulating tumor cells and in all body fluids as protein-bound or incorporated in extracellular vesicles. In these protected forms they are stable and so they can be easily analyzed, even in archival specimens. In this review, the authors will focus on ncRNAs as novel biomarker candidates for PCa diagnosis, prediction, prognosis, and monitoring of therapeutic response and discuss their potential for an implementation into clinical practice.

miR-21-3p is a positive regulator of L1CAM in several human carcinomas

Expression of L1 cell adhesion molecule (L1CAM) occurs frequently in human cancers and is associated with poor prognosis in cancers such as ovarian, endometrial, breast, renal cell carcinoma and pancreatic ductal adenocarcinoma. L1CAM promotes cell motility, invasion, chemoresistance and metastasis formation. Elucidating genetic processes involved in the expression of L1CAM in cancers is of considerable importance. Transcription factors such as SLUG, β-catenin/TCF-LEF, PAX8 and VHL have been implicated in the re-activation of L1CAM in various types of cancers. There is increasing evidence that micro-RNAs can also have strong effects on gene expression. Here we have identified miR-21-3p as a positive regulator of L1CAM expression. Over-expression of miR-21-3p (miR-21*) but not the complementary sequence miR-21-5p (miR-21) could strongly augment L1CAM expression in renal, endometrial and ovarian carcinoma derived cell lines by an unknown mechanism involving transcriptional activation of the L1CAM gene. In patient cohorts from renal, endometrial and ovarian cancers we observed a strong positive correlation of L1CAM and miR-21-3p expressions. Although L1CAM alone was a reliable marker for overall and disease free survival, the combination of L1CAM and miR-21-3p expressions strongly enhanced the predictive power. Our findings shed new light on the complex regulation of L1CAM in cancers and advocate the use of L1CAM/miR-21-3p for diagnostic application.

miR-21 Expression in Cancer Cells may Not Predict Resistance to Adjuvant Trastuzumab in Primary Breast Cancer

Trastuzumab is established as standard care for patients with HER2-positive breast cancer both in the adjuvant and metastatic setting. However, 50% of the patients do not respond to the trastuzumab therapy, and therefore new predictive biomarkers are highly warranted. MicroRNAs (miRs) constitute a new group of biomarkers and their cellular expression can be determined in tumor samples by in situ hybridization (ISH) analysis. miR-21 is highly prevalent and up-regulated in breast cancer and has been linked to drug resistance in clinical and in vitro settings. To determine expression patterns of miR-21 in high-grade breast cancers, we examined miR-21 expression in 22 HER2-positive tumors and 15 HER2-negative high-grade tumors by ISH. The histological examination indicated that patient samples could be divided into three major expression patterns: miR-21 predominantly in tumor stroma, predominantly in cancer cells, or in both stromal and cancer cells. There was no obvious difference between the HER2-positive and HER2-negative tumors in terms of the miR-21 expression patterns and intensities. To explore the possibility that miR-21 expression levels and/or cellular localization could predict resistance to adjuvant trastuzumab in HER2-positive breast cancer patients, we analyzed additional 16 HER2-positive tumors from patients who were treated with trastuzumab in the adjuvant setting. Eight of the 16 patients showed clinical recurrence and were considered resistant. Examination of the miR-21 expression patterns and intensities revealed no association between the miR-21 scores in the cancer cell population (p = 0.69) or the stromal cells population (p = 0.13) and recurrent disease after adjuvant trastuzumab. Thus, our findings show that elevated miR-21 expression does not predict resistance to adjuvant trastuzumab.

NFkappaB activation is essential for miR-21 induction by TGFβ1 in high glucose conditions

Transforming growth factor beta1 (TGFβ1) is a pleiotropic growth factor with a very broad spectrum of effects on wound healing. Chronic non-healing wounds such as diabetic foot ulcers express reduced levels of TGFβ1. On the other hand, our previous studies have shown that the microRNA miR-21 is differentially regulated in diabetic wounds and that it promotes migration of fibroblast cells. Although interplay between TGFβ1 and miR-21 are studied in relation to cancer, their interaction in the context of chronic wounds has not yet been investigated. In this study, we examined if TGFβ1 could stimulate miR-21 in fibroblasts that are subjected to high glucose environment. MiR-21 was, in fact, induced by TGFβ1 in high glucose conditions. The induction by TGFβ1 was dependent on NFκB activation and subsequent ROS generation. TGFβ1 was instrumental in degrading the NFκB inhibitor IκBα and facilitating the nuclear translocation of NFκB p65 subunit. EMSA studies showed enhanced DNA binding activity of NFκB in the presence of TGFβ1. ChIP assay revealed binding of p65 to miR-21 promoter. NFκB activation was also required for the nuclear translocation of Smad 4 protein and subsequent direct interaction of Smad proteins with primary miR-21 as revealed by RNA-IP studies. Our results show that manipulation of TGFβ1-NFκB-miR-21 pathway could serve as an innovative approach towards therapeutics to heal diabetic ulcers.

Chronic atrial fibrillation increases microRNA-21 in human atrial myocytes decreasing L-type calcium current

BACKGROUND

Atrial fibrillation is characterized by progressive atrial structural and electrical changes (atrial remodeling) that favor arrhythmia recurrence and maintenance. Reduction of L-type Ca(2+) current (I(Ca,L)) density is a hallmark of the electrical remodeling. Alterations in atrial microRNAs could contribute to the protein changes underlying atrial fibrillation-induced atrial electrical remodeling. This study was undertaken to compare miR-21 levels in isolated myocytes from atrial appendages obtained from patients in sinus rhythm and with chronic atrial fibrillation (CAF) and to determine whether L-type Ca(2+) channel subunits are targets for miR-21.

METHODS AND RESULTS

Quantitative polymerase chain reaction analysis showed that miR-21 was expressed in human atrial myocytes from patients in sinus rhythm and that its expression was significantly greater in CAF myocytes. There was an inverse correlation between miR-21 and the mRNA of the α1c subunit of the calcium channel (CACNA1C) expression and I(Ca,L) density. Computational analyses predicted that CACNA1C and the mRNA of the β2 subunit of the calcium channel (CACNB2) could be potential targets for miR-21. Luciferase reporter assays demonstrated that miR-21 produced a concentration-dependent decrease in the luciferase activity in Chinese Hamster Ovary cells transfected with CACNA1C and CACNB2 3' untranslated region regions. miR-21 transfection in HL-1 cells produced changes in I(Ca,L) properties qualitatively similar to those produced by CAF (ie, a marked reduction of I(Ca,L) density and shift of the inactivation curves to more depolarized potentials).

CONCLUSIONS

Our results demonstrated that CAF increases miR-21 expression in enzymatically isolated human atrial myocytes. Moreover, it decreases I(Ca,L) density by downregulating Ca(2+) channel subunits expression. These results suggested that this microRNA could participate in the CAF-induced I(Ca,L) downregulation and in the action potential duration shortening that maintains the arrhythmia.

Prognostic value of miR-21 in various cancers: an updating meta-analysis

BACKGROUND

Recently, more and more studies investigated the value of microRNA (miRNA) as a diagnostic or prognostic biomarker in various cancers. MiR-21 was found dysregulated in almost all types of cancers. While the prognostic role of miR-21 in many cancers has been studied, the results were not consistent.

METHODS

We performed a meta-analysis to investigate the correlation between miR-21 and survival of general cancers by calculating pooled hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

The pooled results of 63 published studies showed that elevated miR-21 was a predictor for poor survival of general carcinomas, with pooled HR of 1.91 (95%CI: 1.66-2.19) for OS, 1.42 (95% CI: 1.16-1.74) for DFS and 2.2 (95% CI: 1.64-2.96) for RFS/CSS. MiR-21 was also a prognostic biomarker in the patients who received adjuvant therapy, with pooled HR of 2.4 (95%CI: 1.18-4.9) for OS.

CONCLUSIONS

Our results showed that miR-21 could act as a significant biomarker in the prognosis of various cancers. Further studies are warranted before the application of the useful biomarker in the clinical.

The role of microRNAs in skin fibrosis

Fibrotic skin disorders may be debilitating and impair quality of life. There are few effective treatment options for cutaneous fibrotic diseases. In this review, we discuss our current understanding of the role of microRNAs (miRNAs) in skin fibrosis. miRNAs are a class of small, non-coding RNAs involved in skin fibrosis. These small RNAs range from 18 to 25 nucleotides in length and modify gene expression by binding to target messenger RNA (mRNA), causing degradation of the target mRNA or inhibiting the translation into proteins. We present an overview of the biogenesis, maturation and function of miRNAs. We highlight miRNA’s role in key skin fibrotic processes including: transforming growth factor-beta signaling, extracellular matrix deposition, and fibroblast proliferation and differentiation. Some miRNAs are profibrotic and their upregulation favors these processes contributing to fibrosis, while anti-fibrotic miRNAs inhibit these processes and may be reduced in fibrosis. Finally, we describe the diagnostic and therapeutic significance of miRNAs in the management of skin fibrosis. The discovery that miRNAs are detectable in serum, plasma, and other bodily fluids, and are relatively stable, suggests that miRNAs may serve as valuable biomarkers to monitor disease progression and response to treatment. In the treatment of skin fibrosis, antifibrotic miRNAs may be upregulated using mimics and viral vectors. Conversely, profibrotic miRNAs may be downregulated by employing anti-miRNAs, sponges, erasers and masks. We believe that miRNA-based therapies hold promise as important treatments and may transform the management of fibrotic skin diseases by physicians.