Identification of candidate microRNA biomarkers in renal fibrosis: a meta-analysis of profiling studies

Abstract

The prognostic, diagnostic and therapeutic value of microRNA (miRNA) expression aberrations in renal fibrosis has been studied in recent years. However, the miRNA expression profiling efforts have led to inconsistent results between the studies. The aim of this study was to perform a meta-analysis on the renal fibrosis miRNA expression profiling studies to identify candidate diagnostic biomarkers. We performed comprehensive literature searches in several databases to identify miRNA expression studies of renal fibrosis in animal models and humans. The miRNAs expression data were extracted from 20 included studies, and both miRNA vote-counting strategy and Robust Rank Aggregation method were utilized to identify significant miRNA meta-signatures. The predicted and validated targets of miRNA meta-signature were obtained by using MultiMiR package in 11 databases. Then a gene set enrichment analysis (KEGG, PANTHER pathways and GO processes) were carried out with GeneCodis web tool to recognize pathways that are most strongly influenced by modified expressions of these miRNAs. We recognized in both meta-analysis approaches a significant miRNA meta-signature of five up-regulated (miR-142-3p, miR-223-3p, miR-21-5p, miR-142-5p and miR-214-3p) and two down-regulated (miR-29c-3p and miR-200a-3p) miRNAs. Enrichment analysis confirmed that miRNA meta-signature cooperatively target functionally related genes in signalling and developmental pathways in renal fibrosis. This meta-analysis identified seven highly significant and consistently dysregulated miRNAs from 20 datasets, as the focus of future investigations to discover their potential influence to renal fibrosis and their clinical utility as biomarkers and/or as therapeutic mediators against chronic kidney disease..     

Melatonin ameliorates renal fibroblast-myofibroblast transdifferentiation and renal fibrosis through miR-21-5p regulation

Fibroblast-myofibroblast transdifferentiation (FMT) is widely recognized as the major pathological feature of renal fibrosis. Although melatonin has exerted antifibrogenic activity in many diseases, its role in renal FMT remains unclear. In the present study, the aim was to explore the effect of melatonin on renal FMT and the underlying mechanisms. We established the transforming growth factor (TGF)-β1 stimulated rat renal fibroblast cells (NRK-49F) model in vitro and unilateral ureteral obstruction (UUO) mice model in vivo. We assessed levels of α-smooth muscle actin (α-SMA), col1a1 and fibronectin, STAT3 and AP-1, as well as miR-21-5p and its target genes (Spry1, PTEN, Smurf2 and PDCD4). We found that melatonin reduced the expression of α-SMA, col1a1 and fibronectin, as well as the formation of α-SMA filament in TGF-β1-treated NRK-49F cells. Meanwhile, melatonin inhibited STAT3 phosphorylation, down-regulated miR-21-5p expression, and up-regulated Spry1 and PTEN expression. Moreover, miR-21-5p mimics partially antagonized the anti-fibrotic effect of melatonin. For animal experiments, the results revealed that melatonin remarkably ameliorated UUO-induced renal fibrosis, attenuated the expression of miR-21-5p and pro-fibrotic proteins and elevated Spry1 and PTEN expression. Nevertheless, agomir of miR-21-5p blocked the renoprotective effect of melatonin in UUO mice. These results indicated that melatonin could alleviate TGF-β1-induced renal FMT and UUO-induced renal fibrosis through down-regulation of miR-21-5p. Regulation of miR-21-5p/PTEN and/or miR-21-5p/Spry1 signal might be involved in the anti-fibrotic effect of melatonin in the kidneys of UUO mice.     

新型microRNA—miR-34在肿瘤中的研究进展

miR-34是一类保守的、非编码miRNA。人类miR-34包括miR-34a、miR-34b和miR-34c等,在多种肿瘤中都呈现非正常表达。miR-34通过被p53激活,抑制E2F3、Bcl-2、c—myc、CDK4、CDK6、Cyclin D1以及Cyclin E2的表达,使肿瘤细胞停滞在G1期,抑制肿瘤细胞的生长,诱导肿瘤细胞凋亡,并通过E2F3、SIRT1与p53形成正反馈环路,不断增强其自身和p53的作用。本文就miR-34的研究进展进行综述。     

The role of EMT in renal fibrosis

It is clear that the well-described phenomenon of epithelial–mesenchymal transition (EMT) plays a pivotal role in embryonic development, wound healing, tissue regeneration, organ fibrosis and cancer progression. EMTs have been classified into three subtypes based on the functional consequences and biomarker context in which they are encountered. This review will highlight findings on type II EMT as a direct contributor to the kidney myofibroblast population in the development of renal fibrosis, specifically in diabetic nephropathy, the signalling molecules and the pathways involved in type II EMT and changes in the expression of specific miRNA with the EMT process. These findings have provided new insights into the activation and development of EMT during disease processes and may lead to possible therapeutic interventions to suppress EMTs and potentially reverse organ fibrosis.     

Identification of miR-143 as a tumour suppressor in nasopharyngeal carcinoma based on microRNA expression profiling

Recent evidence has indicated that miRNAs play important roles in carcinogenesis. The identification of dysregulated miRNAs and the target genes they regulate might enhance our understanding of the molecular mechanisms of nasopharyngeal carcinoma (NPC). A microarray analysis was performed to identify dysregulated miRNAs in NPC tissue samples, and protein-coding genes targeted by three or more downregulated miRNAs were selected using miRWalk and used in a pathway enrichment analysis. Nineteen KEGG pathways were selected by DAVID, including the MAPK, focal adhesion, gap junction, ECM–receptor interaction, TGF-beta, and p53 signalling pathways, most of which are involved in NPC carcinogenesis and progression. MiR-143 was significantly downregulated in NPC cell lines and clinical samples. The ectopic expression of miR-143 suppressed NPC cell viability, colony formation, and anchorage-independent growth in vitro, and it inhibited xenograft tumour growth in vivo. Furthermore, KRAS was confirmed as a direct target of miR-143, and silencing KRAS expression suppressed NPC cell viability and proliferation. The miR-143/KRAS pathway provides new insight into the molecular mechanisms that regulate the development and progression of NPC, and it provides novel therapeutic targets for NPC.     

miR-200b precursor can ameliorate renal tubulointerstitial fibrosis

Members of the miR-200 family of micro RNAs (miRNAs) have been shown to inhibit epithelial-mesenchymal transition (EMT). EMT of tubular epithelial cells is the mechanism by which renal fibroblasts are generated. Here we show that miR-200 family members inhibit transforming growth factor-beta (TGF-beta)-induced EMT of tubular cells. Unilateral ureter obstruction (UUO) is a common model of EMT of tubular cells and subsequent tubulointerstitial fibrosis. In order to examine the role of miR-200 family members in tubulointerstitial fibrosis, their expression was investigated in the kidneys of UUO mice. The expression of miR-200 family miRNAs was increased in a time-dependent manner, with induction of miR-200b most pronounced. To clarify the effect of miR-200b on tubulointerstitial fibrosis, we injected miR-200b precursor intravenously. A single injection of 0.5 nM miR-200b precursor was sufficient to inhibit the increase of collagen types I, III and fibronectin in obstructed kidneys, and amelioration of fibrosis was confirmed by observation of the kidneys with Azan staining. miR-200 family members have been previously shown to inhibit EMT by reducing the expression of ZEB-1 and ZEB-2 which are known repressors of E-cadherin. We demonstrated that expression of ZEB-1 and ZEB-2 was increased after ureter obstruction and that administration of the miR-200b precursor reversed this effect. In summary, these results indicate that miR-200 family is up-regulated after ureter obstruction, miR-200b being strongly induced, and that miR-200b ameliorates tubulointerstitial fibrosis in obstructed kidneys. We suggest that members of the miR-200 family, and miR-200b specifically, might constitute novel therapeutic targets in kidney disease.     

Bidirectional integrative regulation of Cav1.2 calcium channel by microRNA miR-103: role in pain

Chronic pain states are characterized by long-term sensitization of spinal cord neurons that relay nociceptive information to the brain. Among the mechanisms involved, up-regulation of Cav1.2-comprising L-type calcium channel (Cav1.2-LTC) in spinal dorsal horn have a crucial role in chronic neuropathic pain. Here, we address a mechanism of translational regulation of this calcium channel. Translational regulation by microRNAs is a key factor in the expression and function of eukaryotic genomes. Because perfect matching to target sequence is not required for inhibition, theoretically, microRNAs could regulate simultaneously multiple mRNAs. We show here that a single microRNA, miR-103, simultaneously regulates the expression of the three subunits forming Cav1.2-LTC in a novel integrative regulation. This regulation is bidirectional since knocking-down or over-expressing miR-103, respectively, up- or down-regulate the level of Cav1.2-LTC translation. Functionally, we show that miR-103 knockdown in naive rats results in hypersensitivity to pain. Moreover, we demonstrate that miR-103 is down-regulated in neuropathic animals and that miR-103 intrathecal applications successfully relieve pain, identifying miR-103 as a novel possible therapeutic target in neuropathic chronic pain.     

miR-21: a small multi-faceted RNA

More than 1000 microRNAs (miRNAs) are expressed in human cells, some tissue or cell type specific, others considered as house-keeping molecules. Functions and direct mRNA targets for some miRNAs have been relatively well studied over the last years. Every miRNA potentially regulates the expression of numerous protein-coding genes (tens to hundreds), but it has become increasingly clear that not all miRNAs are equally important; diverse high-throughput screenings of various systems have identified a limited number of key functional miRNAs over and over again. Particular miRNAs emerge as principal regulators that control major cell functions in various physiological and pathophysiological settings. Since its identification 3 years ago as the miRNA most commonly and strongly up-regulated in human brain tumour glioblastoma [ 1 ], miR-21 has attracted the attention of researchers in various fields, such as development, oncology, stem cell biology and aging, becoming one of the most studied miRNAs, along with let-7, miR-17–92 cluster ('oncomir-1'), miR-155 and a few others. However, an miR-21 knockout mouse has not yet been generated, and the data about miR-21 functions in normal cells are still very limited. In this review, we summarise the current knowledge of miR-21 functions in human disease, with an emphasis on its regulation, oncogenic role, targets in human cancers, potential as a disease biomarker and novel therapeutic target in oncology.     

Role of miR-21 and its signaling pathways in renal diseases

Abstract

miRNAs are endogenous non-coding RNAs that are ～22 nucleotides in length and can have structural, enzymatic and regulatory functions. miRNAs play important roles in the progression of renal fibrosis. miR-21, through a feed-forward loop and a downstream mediator of transforming growth factor-β (TGF-β), amplifies TGF-β signaling and promotes fibrosis. miR-21 is high on the list of non-coding, small, regulatory RNAs that promote renal fibrosis and emerges as a serum biomarker for kidney diseases, but many questions await answers. This review was performed to sum up the role of miR-21 and its signaling pathways in renal diseases.     

miR-375, a microRNA related to diabetes

miR-375 is an important small non-coding RNA that is specifically expressed in islet cells of the pancreas. miR-375 is required for normal pancreatic genesis and influences not only β-cell mass but also α-cell mass. miR-375 is also important to glucose-regulated insulin secretion through the regulation of the expression of Mtpn and Pdk1 genes. When human embryonic stem cells (hESCs) differentiate into endodermal lineages, miR-375 is highly expressed in the definitive endoderm, which suggests that miR-375 may have a distinct role in early development. miR-375 plays an important role in the complex regulatory network of pancreatic development, which could be regulated by pancreatic genes, such as NeuroD1, Ngn3, Pdx1 and Hnf6; additionally, miR-375 regulates genes related to pancreas development, cell growth and proliferation and insulin secretion genes to exert its function. Because of the special role of miR-375, it may be a potential target to treat diabetes. Antagonising miR-375 may enhance the effects of exendin-4 in patients, and controlling the expression of miR-375 could assist mature hESCs-derived β-cells.     

Identification of a glycolysis-related lncRNA prognostic signature for clear cell renal cell carcinoma

Background: The present study investigated the independent prognostic value of glycolysis-related long noncoding (lnc)RNAs in clear cell renal cell carcinoma (ccRCC).Methods: A coexpression analysis of glycolysis-related mRNAs–long noncoding RNAs (lncRNAs) in ccRCC from The Cancer Genome Atlas (TCGA) was carried out. Clinical samples were randomly divided into training and validation sets. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) regression analyses were performed to establish a glycolysis risk model with prognostic value for ccRCC, which was validated in the training and validation sets and in the whole cohort by Kaplan–Meier, univariate and multivariate Cox regression, and receiver operating characteristic (ROC) curve analyses. Principal component analysis (PCA) and functional annotation by gene set enrichment analysis (GSEA) were performed to evaluate the risk model.Results: We identified 297 glycolysis-associated lncRNAs in ccRCC; of these, 7 were found to have prognostic value in ccRCC patients by Kaplan–Meier, univariate and multivariate Cox regression, and ROC curve analyses. The results of the GSEA suggested a close association between the 7-lncRNA signature and glycolysis-related biological processes and pathways.Conclusion: The seven identified glycolysis-related lncRNAs constitute an lncRNA signature with prognostic value for ccRCC and provide potential therapeutic targets for the treatment of ccRCC patients.     

Identification of differentially expressed microRNAs by microarray: a possible role for microRNA genes in pituitary adenomas

MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by targeting mRNA. It has been demonstrated that miRNA expression is altered in many human cancers, suggesting that they may play a role in human neoplasia. To determine whether miRNA expression is altered in pituitary adenomas, we analyzed the entire miRNAome in 32 pituitary adenomas and in 6 normal pituitary samples by microarray and by Real-Time PCR. Here, we show that 30 miRNAs are differentially expressed between normal pituitary and pituitary adenomas. Moreover, 24 miRNAs were identified as a predictive signature of pituitary adenoma and 29 miRNAs were able to predict pituitary adenoma histotype. miRNA expression could differentiate micro- from macro-adenomas and treated from non-treated patient samples. Several of the identified miRNAs are involved in cell proliferation and apoptosis, suggesting that their deregulated expression may be involved in pituitary tumorigenesis. Predictive miRNAs could be potentially useful diagnostic markers, improving the classification of pituitary adenomas.     

miR-155 gene: A typical multifunctional microRNA

In the last years small RNA molecules, i.e. microRNA (miRNA) encoded by miR genes, have been found to play a crucial role in regulating gene expression of a considerable part of plant's and animal's genome. Here, we report the essential information on biogenesis of miRNAs and recent evidence on their important role in human diseases. Emphasis has been given to miR-155, since this molecule represents a typical multifunctional miRNA. Recent data indicate that miR-155 has distinct expression profiles and plays a crucial role in various physiological and pathological processes such as haematopoietic lineage differentiation, immunity, inflammation, cancer, and cardiovascular diseases. Moreover, miR-155 has been found to be implicated in viral infections, particularly in those caused by DNA viruses. The available experimental evidence indicating that miR-155 is over expressed in a variety of malignant tumors allows us to include this miRNA in the list of genes of paramount importance in cancer diagnosis and prognosis. Exogenous molecular control in vivo of miR-155 expression could open up new ways to restrain malignant growth and viral infections, or to attenuate the progression of cardiovascular diseases.     

Identification of miR-17, miR-21, miR-27a,miR-106b and miR-222 as endoplasmic reticulum stress-related potential biomarkers in circulation of patients with atherosclerosis

Molecular Biology Reports - Atherosclerosis and related cardiovascular diseases are among the most common causes of death worldwide. Unfolded protein response, also known as Endoplasmic...     

The role of the tubulointerstitium in radiation-induced renal fibrosis

The functional and morphological response of the remaining hypertrophied kidney in unilaterally nephrectomized rats to single doses of 0-20 Gy X rays was investigated. Functional and histological end points were assessed serially 4-24 weeks postirradiation. Renal irradiation led to time- and dose-dependent reductions in renal function, seen in terms of a decreased glomerular filtration rate, increased blood urea nitrogen, and reduced hematocrit. These changes were accompanied by morphological changes in the glomerular, tubular and interstitial portions of the kidney. However, dose-dependent changes were observed only in terms of tubulointerstitial lesions. Significant increases in the degree of interstitial staining for collagen type III and fibronectin were observed 24 weeks postirradiation. These increases in extracellular matrix components were accompanied by a significant increase in interstitial alpha smooth muscle actin, suggesting activation of interstitial fibroblasts into myofibroblasts. There was no evidence of glomerular Tgfb after renal irradiation. A significant increase in tubular Tgfb staining was only seen 8 weeks postirradiation. In contrast, there was a shift of staining to the interstitium such that by 24 weeks postirradiation interstitial Tgfb staining was significantly greater than that seen in controls. These findings suggest that the tubule epithelial cell and the interstitial fibroblast are both active participants in the development and/or progression of radiation-induced renal fibrosis.     

上皮—间质转化在肾间质纤维化中的作用

上皮－间质转化在发育和纤维化过程中具有重要作用。本文综述了上皮－间质转化发生的过程及其机制的研究进展,尤其是细胞外基质、生长因子、粘附分子及基因对上皮－间质转化的影响。并就在肾间质纤维化过程中因上皮－间质转化致成纤维细胞增多,从而导致肾纤维化的可能作用及其影响因素作一述。     

Identification of miR-7 as an oncogene in renal cell carcinoma

MicroRNA-7 (miR-7) has been described as a tumor suppressor in several human cancers, but the results of a study to identify miRNAs associated with metastatic capability in breast cancer suggested that miR-7 may be characterized as an oncogene. The present study was to determine the expression and function of miR-7 in renal cell carcinoma. Quantitative real-time polymerase chain reaction was used to validate the expressions of miR-7 in 48 paired renal cell carcinomas (RCC) and normal tissues, based on the preliminary sequencing results of miRNAs. Furthermore, the impacts of miR-7 on cell migration, proliferation and apoptosis were analyzed using wound scratch assay, MTT and flow cytometry, respectively. The results demonstrated that miR-7 was up-regulated in RCC compared with normal tissues (p = 0.001). Down-regulation of miR-7 with synthesized inhibitor inhibited cell migration in vitro, suppressed cell proliferation and induced renal cancer cell apoptosis, prompting that miR-7 could be characterized as an oncogene in RCC. The present study was the first to reveal that miR-7 was up-regulated in RCC and it played an important role in RCC by affecting cellular migration, proliferation and apoptosis. Further researches should be conducted to explore the roles and target genes of miR-7 in RCC and other cancers.