Transcription and processing of human microRNA precursors

A lentiviral vector bearing a reverse intron demonstrates superior expression of both proteins and microRNAs

While lentiviral expression vectors are widely used in many facets of molecular biology, due to their ability to stably express heterologous genes in both dividing and non-dividing cells, they suffer from the disadvantage that introns inserted into the vector genome are generally rapidly lost by splicing in packaging cell lines. The presence of an intron, if achievable, has the potential to facilitate the expression of transgene cDNAs, as splicing has been extensively shown to facilitate mRNA biogenesis and function. Moreover, if a stable intron could be introduced into a lentiviral vector, this could greatly facilitate the expression of microRNAs (miRNAs), and especially miRNA clusters, as the introduction of pri-miRNA stems into the exonic region of a lentiviral vector can strongly reduce both vector titer and the expression of any miRNA-linked indicator gene due to cleavage of the vector RNA genome by cellular Drosha. Here, we describe a novel lentiviral vector design in which transgenes and/or miRNAs are expressed using an antisense-orientated, inducible promoter driving an expression cassette bearing a functional intron. We demonstrate that this lentiviral vector, called pTREX, is able to express higher levels of both transgenes and pri-miRNA clusters when compared with a closely similar conventional lentiviral vector.

MiRNA-124 is a link between measles virus persistent infection and cell division of human neuroblastoma cells

Measles virus (MV) infects a variety of lymphoid and non-lymphoid peripheral organs. However, in rare cases, the virus can persistently infect cells within the central nervous system. Although some of the factors that allow MV to persist are known, the contribution of host cell-encoded microRNAs (miRNA) have not been described. MiRNAs are a class of noncoding RNAs transcribed from genomes of all multicellular organisms and some viruses, which regulate gene expression in a sequence-specific manner. We have studied the contribution of host cell-encoded miRNAs to the establishment of MV persistent infection in human neuroblastoma cells. Persistent MV infection was accompanied by differences in the expression profile and levels of several host cell-encoded microRNAs as compared to uninfected cells. MV persistence infection of a human neuroblastoma cell line (UKF-NB-MV), exhibit high miRNA-124 expression, and reduced expression of cyclin dependent kinase 6 (CDK6), a known target of miRNA-124, resulting in slower cell division but not cell death. By contrast, acute MV infection of UKF-NB cells did not result in increased miRNA-124 levels or CDK6 reduction. Ectopic overexpression of miRNA-124 affected cell viability only in UKF-NB-MV cells, causing cell death; implying that miRNA-124 over expression can sensitize cells to death only in the presence of MV persistent infection. To determine if miRNA-124 directly contributes to the establishment of MV persistence, UKF-NB cells overexpressing miRNA-124 were acutely infected, resulting in establishment of persistently infected colonies. We propose that miRNA-124 triggers a CDK6-dependent decrease in cell proliferation, which facilitates the establishment of MV persistence in neuroblastoma cells. To our knowledge, this is the first report to describe the role of a specific miRNA in MV persistence.

Epigenetic regulation of miR-200 as the potential strategy for the therapy against triple-negative breast cancer

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that are involved in the regulation of gene expression at the post-transcriptional level. MicroRNAs play an important role in cancer cell proliferation, survival and apoptosis. Epigenetic modifiers regulate the microRNA expression. Among the epigenetic players, histone deacetylases (HDACs) function as the key regulators of microRNA expression. Epigenetic machineries such as DNA and histone modifying enzymes and various microRNAs have been identified as the important contributors in cancer initiation and progression. Recent studies have shown that developing innovative microRNA-targeting therapies might improve the human health, specifically against the disease areas of high unmet medical need. Thus microRNA based therapeutics are gaining importance for anti-cancer therapy. Studies on Triple negative breast cancer (TNBC) have revealed the early relapse and poor overall survival of patients which needs immediate therapeutic attention. In this report, we focus the effect of HDAC inhibitors on TNBC cell proliferation, regulation of microRNA gene expression by a series of HDAC genes, chromatin epigenetics, epigenetic remodelling at miR-200 promoter and its modulation by various HDACs. We also discuss the need for identifying novel HDAC inhibitors for modulation of miR-200 in triple negative breast cancer.

The Clinical Application of MicroRNAs in Infectious Disease

MicroRNAs (miRNAs) are short single-stranded non-coding RNA sequences that posttranscriptionally regulate up to 60% of protein encoding genes. Evidence is emerging that miRNAs are key mediators of the host response to infection, predominantly by regulating proteins involved in innate and adaptive immune pathways. miRNAs can govern the cellular tropism of some viruses, are implicated in the resistance of some individuals to infections like HIV, and are associated with impaired vaccine response in older people. Not surprisingly, pathogens have evolved ways to undermine the effects of miRNAs on immunity. Recognition of this has led to new experimental treatments, RG-101 and Miravirsen—hepatitis C treatments which target host miRNA. miRNAs are being investigated as novel infection biomarkers, and they are being used to design attenuated vaccines, e.g., against Dengue virus. This comprehensive review synthesizes current knowledge of miRNA in host response to infection with emphasis on potential clinical applications, along with an evaluation of the challenges still to be overcome.

miRNAs and ovarian cancer: An overview

Ovarian cancer (OC) is the sixth most common cancer in women globally. However, even with the advances in detection and therapeutics it still represents the most dangerous gynecologic malignancy in women of the industrialized countries. The discovery of micro-RNAs (miRNA), a small noncoding RNA molecule targeting multiple mRNAs and regulation of gene expression by triggering translation repression and/or RNA degradation, has revealed the existence of a new array for regulation of genes involved in cancer. This review summarizes the current knowledge regarding the role of miRNAs expression in OC. It also provides information about potential clinical relevance of circulating miRNAs for OC diagnosis, prognosis, and therapeutics. The identification of functional targets for miRNAs represents a major obstacle in our understanding of microRNA function in OC, but significant progress is being made. The better understanding of the role of microRNA expression in ovarian cancer may provide new array for the detection, diagnosis, and therapy of the OC.

Epithelial-to-Mesenchymal Transition and MicroRNAs in Lung Cancer

Despite major advances, non-small cell lung cancer (NSCLC) remains the major cause of cancer-related death in developed countries. Metastasis and drug resistance are the main factors contributing to relapse and death. Epithelial-to-mesenchymal transition (EMT) is a complex molecular and cellular process involved in tissue remodelling that was extensively studied as an actor of tumour progression, metastasis and drug resistance in many cancer types and in lung cancers. Here we described with an emphasis on NSCLC how the changes in signalling pathways, transcription factors expression or microRNAs that occur in cancer promote EMT. Understanding the biology of EMT will help to define reversing process and treatment strategies. We will see that this complex mechanism is related to inflammation, cell mobility and stem cell features and that it is a dynamic process. The existence of intermediate phenotypes and tumour heterogeneity may be debated in the literature concerning EMT markers, EMT signatures and clinical consequences in NSCLC. However, given the role of EMT in metastasis and in drug resistance the development of EMT inhibitors is an interesting approach to counteract tumour progression and drug resistance. This review describes EMT involvement in cancer with an emphasis on NSCLC and microRNA regulation.

Identification and expression analysis of <i>miR-144-5p</i> and <i>miR-130b-5p</i> in dairy cattle

Abstract. MicroRNAs (miRNAs) can coordinate the main pathways involved in innate and adaptive immune responses by regulating gene expression. To explore the resistance to mastitis in cows, miR-144-5p and miR-130b-5p were identified in bovine mammary gland tissue and 14 potential target genes belonging to the chemokine signaling pathway, the arginine and proline metabolism pathway and the mRNA surveillance pathway were predicted. Subsequently, we estimated the relative expression of miR-144-5p and miR-130b-5p in cow mammary tissues by using stem-loop quantitative real-time polymerase chain reaction. The results showed that the relative expression of miR-144-5p and miR-130b-5p in the mastitis-infected mammary tissues (n = 5) was significantly downregulated 0.14-fold (p < 0. 01) and upregulated 3.34-fold (p < 0. 01), respectively, compared to healthy tissues (n = 5). Our findings reveal that miR-144-5p and miR-130b-5p may have important roles in resistance to mastitis in dairy cattle.

A Tiny RNA that Packs a Big Punch: The Critical Role of a Viral miR-155 Ortholog in Lymphomagenesis in Marek's Disease

MicroRNAs (miRNAs) are small non-coding RNAs that have been identified in animals, plants, and viruses. These small RNAs play important roles in post-transcriptional regulation of various cellular processes, including development, differentiation, and all aspects of cancer biology. Rapid-onset T-cell lymphoma of chickens, namely Marek’s disease (MD), induced by Gallid alphaherpesvirus 2 (GaHV2), could provide an ideal natural animal model for herpesvirus-related cancer research. GaHV2 encodes 26 mature miRNAs derived from 14 precursors assembled in three distinct gene clusters in the viral genome. One of the most highly expressed GaHV2 miRNAs, miR-M4-5p, shows high sequence similarity to the cellular miR-155 and the miR-K12-11 encoded by Kaposi’s sarcoma-associated herpesvirus, particularly in the miRNA “seed region.” As with miR-K12-11, miR-M4-5p shares a common set of host and viral target genes with miR-155, suggesting that they may target the same regulatory cellular networks; however, differences in regulatory function between miR-155 and miR-M4-5p may distinguish non-viral and viral mediated tumorigenesis. In this review, we focus on the functions of miR-M4-5p as the viral ortholog of miR-155 to explore how the virus mimics a host pathway to benefit the viral life cycle and trigger virus-induced tumorigenesis.

The Fragment HMGA2-sh-3p20 from HMGA2 mRNA 3'UTR Promotes the Growth of Hepatoma Cells by Upregulating HMGA2

High mobility group A2 (HMGA2) plays a crucial role in the development of cancer. However, the mechanism by which HMGA2 promotes the growth of hepatocellular carcinoma (HCC) remains unclear. Here, we explore the hypothesis that HMGA2 may enhance the growth of hepatoma cells through a fragment based on the secondary structure of HMGA2 mRNA 3′-untranslated region (3′UTR). Bioinformatics analysis showed that HMGA2 mRNA displayed a hairpin structure within its 3′UTR, termed HMGA2-sh. Mechanistically, RNA immunoprecipitation assays showed that the microprocessor Drosha or DGCR8 interacted with HMGA2 mRNA in hepatoma cells. Then, Dicer contributes to the generation of the fragment HMGA2-sh-3p20 from the HMGA2-sh. HMGA2-sh-3p20 was screened by PCR analysis. Interestingly, HMGA2-sh-3p20 increased the expression of HMGA2 through antagonizing the tristetraprolin (TTP)-mediated degradation of HMGA2. HMGA2-sh-3p20 inhibited the expression of PTEN by targeting the 3′UTR of PTEN mRNA. In addition, the overexpression of PTEN could downregulate HMGA2 expression. Significantly, we documented the ability of HMGA2-sh-3p20 to promote the growth of hepatoma cells in vitro and in vivo. Thus, we conclude that the fragment HMGA2-sh-3p20 from HMGA2 mRNA 3′UTR promotes the growth of hepatoma cells by upregulating HMGA2. Our finding provides new insights into the mechanism by which HMGA2 enhances hepatocarcinogenesis.

Non-coding RNAs in Development and Disease: Background, Mechanisms, and Therapeutic Approaches

Advances in RNA-sequencing techniques have led to the discovery of thousands of non-coding transcripts with unknown function. There are several types of non-coding linear RNAs such as microRNAs (miRNA) and long non-coding RNAs (lncRNA), as well as circular RNAs (circRNA) consisting of a closed continuous loop. This review guides the reader through important aspects of non-coding RNA biology. This includes their biogenesis, mode of actions, physiological function, as well as their role in the disease context (such as in cancer or the cardiovascular system). We specifically focus on non-coding RNAs as potential therapeutic targets and diagnostic biomarkers.

EBV‑BART‑6‑3p and cellular microRNA‑197 compromise the immune defense of host cells in EBV‑positive Burkitt lymphoma

The present study aimed to identify the association between Epstein‑Barr virus (EBV) microRNA (miRNA) and cellular miRNA in compromising the immune system, which contributes to the development of Burkitt lymphoma (BL). The present study selected cellular miR‑197 as the focus of the experiments due to the previous report that it is differentially expressed and the observation that interleukin‑6 receptor (IL‑6R) is a virtual target of miR‑197 and EBV‑BamHI A region rightward transcript (BART)‑6‑3p. In the present study, IL‑6R was confirmed as a target of cellular miR‑197 using a luciferase assay, and the negative regulatory association between miRNA (miR‑197 and EBV‑BART‑6‑3p) and mRNA (IL‑6R) was confirmed by the observation that IL‑6R was downregulated in EBV‑positive Burkitt lymphoma and that miR‑197 was upregulated. Additionally, mimics of EBV‑BART‑6‑3p and miR‑197 were introduced into lymphoma cells, and it was found that EBV‑BART‑6‑3p and miR‑197 synergistically reduced the expression of IL‑6R. These findings improved current understanding of the role of miR‑197/ EBV‑BART‑6‑3p and their target, IL‑6R, in the development of EBV‑positive BL, and they may offer potential as novel therapeutic targets for the treatment of EBV‑positive malignancies.

Hypoxia-induced hsa-miR-101 promotes glycolysis by targeting TIGAR mRNA in clear cell renal cell carcinoma

Increasing evidence suggests that microRNAs (miRNAs) are essential in carcinogenesis, therefore, the present study investigated the role of hsa‑miR‑101 in renal tumorigenesis and cancer development. On identification of its expression pattern, it may serve as a diagnostic biomarker for clear cell renal cell carcinoma (ccRCC). In the present study, 10 pairs of ccRCC and noncancerous tissue samples were obtained to examine whether the expression of hsa‑miR‑101 is linked to cancer. The data obtained were validated using reverse transcription‑quantitative polymerase chain reaction analysis. The levels of hsa‑miR‑101 were examined following exposure to hypoxia in ACHN and HK‑2 cells. As a predicted target, the mRNA and protein levels of TP53‑induced glycolysis and apoptosis regulator (TIGAR) were then assessed. A pcDNA‑GFP‑miR‑101 plasmid was stably transfected into ACHN and HK‑2 cells, following which the effects of hsa‑miR‑101 on the expression of TIGAR and inhibition of glycolysis were investigated. The present study also examined the association between the level of hsa‑miR‑101 and kidney tumors. It was identified that the expression level was significantly higher in the ccRCC tissues, compared with that in the corresponding noncancerous tissues. The expression values for the upregulated miRNA ranged between 4.6‑ and 67.9‑fold. On demonstrating the functional link between hypoxia and the expression of miRNAs changes in the expression of hsa‑miR‑101 were examined following hypoxia exposure in kidney tumor and non‑tumor cell lines. It was shown that hypoxia exposure significantly induced hsa‑miR‑101. The hypoxia‑induced upregulation of hsa‑miR‑101 repressed the activity of TIGAR by targeting TIGAR mRNA and promoting glycolysis. The results showed that the upregulation of hsa‑miR‑101 in ccRCC was induced by hypoxia. Its expression deceased the protein expression of TIGAR and promoted glycolysis. This regulatory pathway may represent a novel mechanism of carcinogenesis and requires further investigation.

Lentiviral vector-encoded microRNA-based shRNA-mediated gene knockdown of N-methyl-D-aspartate receptors in skin reduces pain

BACKGROUND AND PURPOSE

RNA polymerase II promoters that drive the expression of rationally designed primary microRNA-based shRNA, for example, shRNAmir, can produce more potent gene knockdown than RNA polymerase III promoters. Antagonists of peripheral N methyl-D-aspartate (NMDA) receptors that do not interfere with central glutamate processing would prevent the development of adverse central nervous system effects. Thus, in this study, we examined the effects of gene silencing and antinociception on formalin- and Complete Freund's adjuvant (CFA)-induced pain in rats by subcutaneously injecting a lentiviral vector encoding a shRNAmir that targets the NR1 subunit of the NMDA receptor.

METHODS

Rats received intradermal injections of different doses of NR1 shRNAmir at different time points before injection of formalin. Pain behavior was assessed by monitoring the paw flinch response, paw withdrawal threshold, and thermal withdrawal latency. We then analyzed NR1 messenger RNA and protein expression in skin and the L5 dorsal root ganglion (DRG).

RESULTS

We found that intradermal injection of 1, 5, and 10 μg of shRNAmir significantly inhibited flinch responses (p < .05). Administration of 5 μg of shRNAmir resulted in the attenuation of CFA-induced mechanical allodynia, but did not affect the time spent on the rotarod. Real-time polymerase chain reaction and western blotting revealed that NR1 mRNA and protein levels were significantly lower in all NR1 shRNAmir1 groups than in controls (p < .05). There was a significant reduction in the percentage of NR1- and pERK-positive neurons in the DRG ipsilateral to shRNAmir treated paws (p < .05). The effect of antinociception and inhibition of NR1 expression by NR1 shRNAmir was evident on day 3 and persisted for 7 days after injection of 5 μg of vector.

CONCLUSION

Peripheral administration of the vector-encoded NR1 shRNAmir is a promising therapy for persistent inflammatory pain.

MicroRNAs in the Host Response to Viral Infections of Veterinary Importance

The discovery of small regulatory non-coding RNAs has been an exciting advance in the field of genomics. MicroRNAs (miRNAs) are endogenous RNA molecules, approximately 22 nucleotides in length, that regulate gene expression, mostly at the posttranscriptional level. MiRNA profiling technologies have made it possible to identify and quantify novel miRNAs and to study their regulation and potential roles in disease pathogenesis. Although miRNAs have been extensively investigated in viral infections of humans, their implications in viral diseases affecting animals of veterinary importance are much less understood. The number of annotated miRNAs in different animal species is growing continuously, and novel roles in regulating host–pathogen interactions are being discovered, for instance, miRNA-mediated augmentation of viral transcription and replication. In this review, we present an overview of synthesis and function of miRNAs and an update on the current state of research on host-encoded miRNAs in the genesis of viral infectious diseases in their natural animal host as well as in selected in vivo and in vitro laboratory models.

Differential role of microRNAs in prognosis, diagnosis, and therapy of ovarian cancer

Ovarian cancer (OC) is the most lethal of malignant gynecological cancers, and has a very poor prognosis, frequently, attributable to late diagnosis and responsiveness to chemotherapy. In spite of the technological and medical approaches over the past four decades, involving the progression of several biological markers (mRNA and proteins biomarkers), the mortality rate of OC remains a challenge due to its late diagnosis, which is expressly ascribed to low specificities and sensitivities. Consequently, there is a crucial need for novel diagnostic and prognostic markers that can advance and initiate more individualized treatment, finally increasing survival of the patients. MiRNAs are non-coding RNAs that control target genes post transcriptionally. They are included in tumorigenesis, apoptosis, proliferation, invasion, metastasis, and chemoresistance. Several studies have within the last decade demonstrated that miRNAs are dysregulated in OC and have possibilities as diagnostic and prognostic biomarkers for OC. Additionally; recent studies have also focused on miRNAs as predictors of chemotherapy sensitivities and their potential as therapeutic targets. In this review, we discuss the current data involving the accumulating evidence of the altered expression of miRNAs in OC, their role in diagnosis, prognosis, and forecast of response to therapy. Given the heterogeneity of this disease, it is likely that advances in long-term survival might be also attained by translating the recent insights of miRNAs participation in OC into new targeted therapies that will have a crucial effect on the management of ovarian cancer.

Polymorphisms in GEMIN4 and AGO1 Genes Are Associated with the Risk of Lung Cancer: A Case-Control Study in Chinese Female Non-Smokers

MicroRNA biosynthesis genes can affect the regulatory effect of global microRNAs to target mRNA and hence influence the genesis and development of human cancer. Here, we selected five single nucleotide polymorphisms (SNPs) (rs7813, rs2740349, rs2291778, rs910924, rs595961) in two key microRNA biosynthesis genes (GEMIN4 and AGO1) and systematically evaluated the association between these SNPs, the gene-environment interaction and lung cancer risk. To control the impact of cigarette smoking on lung cancer, we recruited Chinese female non-smokers for the study. The total number of lung cancer cases and cancer-free controls were 473 and 395 in the case-control study. Four SNPs showed statistically significant associations with lung cancer risk. After Bonferroni correction, rs7813 and rs595961 were evidently still associated with lung cancer risk. In the stratified analysis, our results revealed that all five SNPs were associated with the risk of lung adenocarcinoma; after Bonferroni correction, significant association was maintained for rs7813, rs910924 and rs595961. Haplotype analysis showed GEMIN4 haplotype C-A-G-T was a protective haplotype for lung cancer. In the combined unfavorable genotype analysis, with the increasing number of unfavorable genotypes, a progressively increased gene-dose effect was observed in lung adenocarcinoma. We also found that individuals exposed to cooking oil fumes showed a relatively high risk of lung cancer, but no interactions were found between cooking oil fume exposure or passive smoking exposure with these SNPs, either on an additive scale or a multiplicative scale. Overall, this is the first study showing that rs7813 and rs595961 could be meaningful as genetic markers for lung cancer risk.

The role of microRNAs in the pathogenesis of autoimmune diseases

MicroRNAs (miRNAs) are single-stranded, endogenous non-coding small RNAs, ranging from 18 to 25 nucleotides in length. Growing evidence suggests that miRNAs are essential in regulating gene expression, cell development, differentiation and function. Autoimmune diseases are a family of chronic systemic inflammatory diseases. Recent findings on miRNA expression profiles have been suggesting their role as biomarkers in autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and Sjögren's syndrome. In this review, we summarize the characteristics of miRNAs and their functional role in the immune system and autoimmune diseases including systemic lupus erythematosus, primary Sjögren's syndrome, rheumatoid arthritis, systemic sclerosis, multiple sclerosis and psoriasis; moreover, we depict the advantages of miRNAs in modern diagnostics.

Down-regulation of the microRNA processing enzyme Dicer is a prognostic factor in human colorectal cancer

AIMS

MicroRNA deregulation is a key feature of cancer; however, the molecular mechanisms underlying deregulation are unknown. Dicer is a central enzyme in microRNA processing essential for production of mature microRNAs which, in turn, regulate gene expression post-transcription. The aim was to investigate whether Dicer expression in colorectal cancer correlates with conventional clinicopathological parameters and patient survival.

METHODS AND RESULTS

Immunohistochemical staining for Dicer was performed on tissue microarrays of 331 samples from patients with primary colorectal carcinoma. A subset (19.6%) of colorectal carcinomas was negative for Dicer. Dicer protein expression was associated significantly and inversely with disease (WHO) stage (P = 0.029), tumour grade (P = 0.001), tumour stage (P = 0.022) and nodal metastasis (P = 0.004). Negative expression of Dicer correlated significantly with shortened overall survival (P = 0.007) and was independent of other prognostic factors in multivariate analysis (Cox regression: P = 0.035, hazard ratio=1.6; 95% confidence interval 1.034-2.513). Additionally, in univariate analysis, an association of Dicer expression with survival was observed in subsets of patients without metastasis (P = 0.026), older patients (P = 0.005) and patients with advanced tumour stage (P = 0.022).

CONCLUSION

Dicer deregulation is linked significantly to adverse disease state and decreased overall survival in colorectal cancer. Our data suggest that reduced Dicer expression might contribute to tumour progression in colorectal cancer.

MicroRNAs as key mediators of hepatic detoxification

MicroRNAs (miRNAs) are a class of short noncoding RNAs that modulate gene expression at both transcriptional and post-transcriptional levels. Many studies have extensively revealed the significance of miRNAs in mediating liver development and diseases. However, their role in hepatic detoxification processes has been explored only recently. In this review, we summarized the up-to-date knowledge about miRNA dependent regulation of enzymes involved in all three phases of the drugs and xenobiotics detoxification process. We also discussed the role of miRNA in regulating some upstream nuclear receptors involving gene expression of enzymes for detoxification process in liver. The toxicological significance of miRNAs in liver diseases and future research perspectives are finally presented.

Post-transcriptional modulation of protein phosphatase PPP2CA and tumor suppressor PTEN by endogenous siRNA cleaved from hairpin within PTEN mRNA 3'UTR in human liver cells

Aim:

Increasing evidence shows that mRNAs exert regulatory function along with coding proteins. Recently we report that a hairpin within YAP mRNA 3′UTR can modulate the Hippo signaling pathway. PTEN is a tumor suppressor, and is mutated in human cancers. In this study we examined whether PTEN mRNA 3′UTR contained a hairpin structure that could regulate gene regulation at the post-transcriptional level.

Methods:

The secondary structure of PTEN mRNA 3′UTR was analyzed using RNAdraw and RNAstructure. Function of hairpin structure derived from the PTEN mRNA 3′UTR was examined using luciferase reporter assay, RT-PCR and Western blotting. RNA-immunoprecipitation (RIP) assay was used to analyze the interaction between PTEN mRNA and microprocessor Drosha and DGCR8. Endogenous siRNA (esiRNA) derived from PTEN mRNA 3′UTR was identified by RT-PCR and rt-PCR, and its target genes were predicted using RNAhybrid.

Results:

A bioinformatics analysis revealed that PTEN mRNA contained a hairpin structure (termed PTEN-sh) within 3′UTR, which markedly increased the reporter activities of AP-1 and NF-κB in 293T cells. Moreover, treatment with PTEN-sh (1 and 2 μg) dose-dependently inhibited the expression of PTEN in human liver L-O2 cells. RIP assay demonstrated that the microprocessor Drosha and DGCR8 was bound to PTEN-sh in L-O2 cells, leading to the cleavage of PTEN-sh from PTEN mRNA 3′UTR. In addition, microprocessor Dicer was involved in the processing of PTEN-sh. Interestingly, esiRNA (termed PTEN-sh-3p21) cleaved from PTEN-sh was identified in 293T cells and human liver tissues, which was found to target the mRNA 3′UTRs of protein phosphatase PPP2CA and PTEN in L-O2 cells. Treatment of L-O2 or Chang liver cells with PTEN-sh-3p21 (50, 100 nmol/L) promoted the cell proliferation in dose- and time-dependent manners.

Conclusion:

The endogenous siRNA (PTEN-sh-3p21) cleaved from PTEN-sh within PTEN mRNA 3′UTR modulates PPP2CA and PTEN at the post-transcriptional level in liver cells.

A Comprehensive Review on the Genetic Regulation of Cisplatin-induced Nephrotoxicity

Cisplatin (CDDP) is a well-known antineoplastic drug which has been extensively utilized over the last decades in the treatment of numerous kinds of tumors. However, CDDP induces a wide range of toxicities in a dose-dependent manner, among which nephrotoxicity is of particular importance. Still, the mechanism of CDDP-induced renal damage is not completely understood; moreover, the knowledge about the role of microRNAs (miRNAs) in the nephrotoxic response is still unknown. miRNAs are known to interact with the representative members of a diverse range of regulatory pathways (including postnatal development, proliferation, inflammation and fibrosis) and pathological conditions, including kidney diseases: polycystic kidney diseases (PKDs), diabetic nephropathy (DN), kidney cancer, and drug-induced kidney injury. In this review, we shed light on the following important aspects: (i) information on genes/proteins and their interactions with previously known pathways engaged with CDDP-induced nephrotoxicity, (ii) information on newly discovered biomarkers, especially, miRNAs for detecting CDDP-induced nephrotoxicity and (iii) information to improve our understanding on CDDP. This information will not only help the researchers belonging to nephrotoxicity field, but also supply an indisputable help for oncologists to better understand and manage the side effects induced by CDDP during cancer treatment. Moreover, we provide up-to-date information about different in vivo and in vitro models that have been utilized over the last decades to study CDDP-induced renal injury. Taken together, this review offers a comprehensive network on genes, miRNAs, pathways and animal models which will serve as a useful resource to understand the molecular mechanism of CDDP-induced nephrotoxicity.

Oligonucleotide-based theranostic nanoparticles in cancer therapy

Theranostic approaches, combining the functionality of both therapy and imaging, have shown potential in cancer nanomedicine. Oligonucleotides such as small interfering RNA and microRNA, which are powerful therapeutic agents, have been effectively employed in theranostic systems against various cancers. Nanoparticles are used to deliver oligonucleotides into tumors by passive or active targeting while protecting the oligonucleotides from nucleases in the extracellular environment. The use of quantum dots, iron oxide nanoparticles and gold nanoparticles and tagging with contrast agents, like fluorescent dyes, optical or magnetic agents and various radioisotopes, has facilitated early detection of tumors and evaluation of therapeutic efficacy. In this article, we review the advantages of theranostic applications in cancer therapy and imaging, with special attention to oligonucleotide-based therapeutics.

The inhibition of microRNAs by HIV-1 Tat suppresses beta catenin activity in astrocytes

Background

Long term infection with HIV-1, even in the context of therapy, leads to chronic health problems including an array of neurocognitive dysfunctions. The viral Tat protein has previously been implicated in neuropathogenesis through its effect on astrocytes. Tat has also been shown to inhibit the biogenesis of miRNAs by inhibiting the activity of the cellular Dicer protein in an RNA dependent fashion. Whether there is a mechanistic connection between the ability of HIV-1 Tat to alter miRNAs and its observed effects on cells of the central nervous system has not been well examined.

Results

Here, we examined the ability of HIV-1 Tat to bind to and inhibit the production of over 300 cellular miRNAs. We found that the Tat protein only binds to and inhibits a fraction of the total cellular miRNAs. By mapping the downstream targets of these miRNAs we have determined a possible role for Tat alterations of miRNAs in the development of neuropathogenesis. Specifically, this work points to suppression of miRNAs function as the mechanism for Tat suppression of β-catenin activity.

Conclusions

The discovery that HIV-1 Tat inhibits only a fraction of miRNAs opens new areas of research regarding changes in cellular pathways through suppression of RNA interference. Our initial analysis strongly suggests that these pathways may contribute to HIV-1 disruption of the central nervous system.

Electronic supplementary material

The online version of this article (doi:10.1186/s12977-016-0256-y) contains supplementary material, which is available to authorized users.

Estrogen repression of microRNA as a potential cause of cancer

MicroRNAs (miRNAs) are endogenous small molecules that regulate gene expression and have been implicated in the pathogenesis of many human diseases, including cancer. This review describes the results that show a global repression in miRNA expression in various tumors and cancer cell lines. Intriguingly, recent discoveries have shown a widespread downregulation of miRNA after exposure to the steroid hormone estrogen. The integration of the results suggests that estrogen-dependent repression of miRNA is a potential cause of cancer.

Current status on microRNAs as biomarkers for ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy in the Western world, and has a very poor prognosis, often due to late diagnosis and emergence of chemotherapy resistance. Therefore, there is an essential need for new diagnostic and prognostic markers that can improve and initiate more personalized treatment, eventually improving survival of the patients. MicroRNAs are small, non-coding RNA molecules, that post-transcriptionally regulate gene expression. Several studies have within the last decade shown that microRNAs are deregulated in OC and have potential as diagnostic and prognostic biomarkers for OC. Recently studies have also focused on microRNAs as predictors of chemotherapy responses and their potential as therapeutic targets. However, many of the published studies are difficult to interpret as a whole due to various methods of analysis. Future focus should be aimed at developing a general standardized analytical method, which can limit differences between studies thus allowing easier comparison across them. In addition, validation of studies in independent series that ideally should be histotype-specific is essential to determine the clinical role of microRNAs in different types of OC. In this review we summarize the current knowledge of microRNAs as potential biomarkers for OC, with focus on their clinical relevance.

MicroRNA: a new and promising potential biomarker for diagnosis and prognosis of ovarian cancer

Epithelial ovarian cancer (EOC) is the leading cause of death among all gynecological malignancies. Despite the technological and medical advances over the past four decades, such as the development of several biological markers (mRNA and proteins biomarkers), the mortality rate of ovarian cancer remains a challenge because of its late diagnosis, which is specifically attributed to low specificities and sensitivities. Under this compulsive scenario, recent advances in expression biology have shifted in identifying and developing specific and sensitive biomarkers, such as microRNAs (miRNAs) for cancer diagnosis and prognosis. MiRNAs are a novel class of small non-coding RNAs that deregulate gene expression at the posttranscriptional level, either by translational repression or by mRNA degradation. These mechanisms may be involved in a complex cascade of cellular events associated with the pathophysiology of many types of cancer. MiRNAs are easily detectable in tissue and blood samples of cancer patients. Therefore, miRNAs hold good promise as potential biomarkers in ovarian cancer. In this review, we attempted to provide a comprehensive profile of key miRNAs involved in ovarian carcinoma to establish miRNAs as more reliable non-invasive clinical biomarkers for early detection of ovarian cancer compared with protein and DNA biomarkers.

Screening of Pre-miRNA-155 Binding Peptides for Apoptosis Inducing Activity Using Peptide Microarrays

MicroRNA-155, one of the most potent miRNAs that suppress apoptosis in human cancer, is overexpressed in numerous cancers, and it displays oncogenic activity. Peptide microarrays, constructed by immobilizing 185 peptides containing the C-terminal hydrazide onto epoxide-derivatized glass slides, were employed to evaluate peptide binding properties of pre-miRNA-155 and to identify its binding peptides. Two peptides, which were identified based on the results of peptide microarray and in vitro Dicer inhibition studies, were found to inhibit generation of mature miRNA-155 catalyzed by Dicer and to enhance expression of miRNA-155 target genes in cells. In addition, the results of cell experiments indicate that peptide inhibitors promote apoptotic cell death via a caspase-dependent pathway. Finally, observations made in NMR and molecular modeling studies suggest that a peptide inhibitor preferentially binds to the upper bulge and apical stem-loop region of pre-miRNA-155, thereby suppressing Dicer-mediated miRNA-155 processing.

Uterine leiomyosarcoma and endometrial stromal sarcoma have unique miRNA signatures

OBJECTIVE

To compare the microRNA (miRNA) profiles of uterine endometrial stromal sarcoma (ESS) and leiomyosarcoma (LMS), and to compare the miRNA signatures of primary and metastatic uterine LMS.

METHODS

Eight primary LMS, 9 primary ESS and 8 metastatic LMS were analyzed for miRNA profiles using TaqMan Human miRNA Array Cards. Findings for 20 differentially expressed miRNAs were validated in a series of 44 uterine sarcomas (9 primary uterine ESS, 17 primary uterine LMS, 18 metastatic LMS) using qPCR. Frizzled-6 protein expression was analyzed in 30 LMS (15 primary, 15 metastases). Frizzled-6 was silenced in SK-LMS-1 uterine LMS cells using siRNA and the effect on invasion, wound healing and matrix metalloproteinase-2 (MMP2) activity was assessed.

RESULTS

Ninety-four miRNAs were significantly differentially expressed in ESS and LMS, of which 76 were overexpressed in ESS and 18 overexpressed in LMS. Forty-nine miRNAs were differentially expressed in primary and metastatic LMS, of which 45 were overexpressed in primary LMS and 4 in metastases. Differential expression was confirmed for 10/20 miRNA analyzed using qPCR. Frizzled-6 silencing in SK-LMS-1 cells significantly inhibited cellular invasion, wound healing and MMP-2 activity.

CONCLUSIONS

Differential miRNA signatures of ESS and LMS provide novel data regarding transcriptional regulation in these cancers, based on which new potential diagnostic markers, prognostic biomarkers and therapeutic targets may be explored. Differences in miRNA profiles of primary and metastatic LMS may improve our understanding of disease progression in this aggressive malignancy.

MicroRNA and Pathogenesis of Enterovirus Infection

There are no currently available specific antiviral therapies for non-polio Enterovirus infections. Although several vaccines have entered clinical trials, the efficacy requires further evaluation, particularly for cross-strain protective activity. Curing patients with viral infections is a public health problem due to antigen alterations and drug resistance caused by the high genomic mutation rate. To conquer these limits in the development of anti-Enterovirus treatments, a comprehensive understanding of the interactions between Enterovirus and host cells is urgently needed. MicroRNA (miRNA) constitutes the biggest family of gene regulators in mammalian cells and regulates almost a half of all human genes. The roles of miRNAs in Enterovirus pathogenesis have recently begun to be noted. In this review, we shed light on recent advances in the understanding of Enterovirus infection-modulated miRNAs. The impacts of altered host miRNAs on cellular processes, including immune escape, apoptosis, signal transduction, shutdown of host protein synthesis and viral replication, are discussed. Finally, miRNA-based medication provides a promising strategy for the development of antiviral therapy.

Electroacupuncture inhibits inflammatory injury by targeting the miR-9-mediated NF-κB signaling pathway following ischemic stroke

The aim of the present study was to investigate the neuroprotective mechanism of the miR-9-mediated activation of the nuclear factor (NF)-κB signaling pathway by electroacupuncture (EA) stimulation of the Quchi (LI11) and Zusanli (ST36) acupoints in a rat model of middle cerebral artery occlusion (MCAO). The present study demonstrated that EA alleviated the symptoms of neurological deficits and reduced the infarct volume in the rat brains. The expression of miR-9 in the peri-infarct cortex was increased in the EA group compared with the MCAO group, and the expression of NF-κB signaling pathway-associated factors, NF-κB p65, tumor necrosis factor (TNF)-α and interleukin (IL)-1β were reduced. Notably, miR-9 inhibitors were revealed to have the ability to suppress EA-alleviated cerebral inflammation and the expression of NF-κB downstream-related factors, NF-κB p65, TNF-α and IL-1β, and caused no alteration on the level of NF-κB upstream-related protein inhibitor of κBα, suggesting that the cerebral protective efficacy of EA targets miR-9-mediated NF-κB downstream pathway following ischemic stroke.

A cardiac myocyte-restricted Lin28/let-7 regulatory axis promotes hypoxia-mediated apoptosis by inducing the AKT signaling suppressor PIK3IP1

RATIONALE

The let-7 family of microRNAs (miRs) regulates critical cell functions, including survival signaling, differentiation, metabolic control and glucose utilization. These functions may be important during myocardial ischemia. MiR-let-7 expression is under tight temporal and spatial control through multiple redundant mechanisms that may be stage-, isoform- and tissue-specific.

OBJECTIVE

To determine the mechanisms and functional consequences of miR-let-7 regulation by hypoxia in the heart.

METHODS AND RESULTS

MiR-let-7a, -7c and -7g were downregulated in the adult mouse heart early after coronary occlusion, and in neonatal rat ventricular myocytes subjected to hypoxia. Let-7 repression did not require glucose depletion, and occurred at a post-transcriptional level. Hypoxia also induced the RNA binding protein Lin28, a negative regulator of let-7. Hypoxia ineither induced Lin28 nor repressed miR-let-7 in cardiac fibroblasts. Both changes were abrogated by treatment with the histone deacetylase inhibitor trichostatin A. Restoration of let-7g to hypoxic myocytes and to ischemia-reperfused mouse hearts in vivo via lentiviral transduction potentiated the hypoxia-induced phosphorylation and activation of Akt, and prevented hypoxia-dependent caspase activation and death. Mechanistically, phosphatidyl inositol 3-kinase interacting protein 1 (Pik3ip1), a negative regulator of PI3K, was identified as a novel target of miR-let-7 by a crosslinking technique showing that miR-let-7g specifically targets Pik3ip1 to the cardiac myocyte Argonaute complex RISC. Finally, in non-failing and failing human myocardium, we found specific inverse relationships between Lin28 and miR-let-7g, and between miR-let-7g and PIK3IP1.

CONCLUSION

A conserved hypoxia-responsive Lin28-miR-let-7-Pik3ip1 regulatory axis is specific to cardiac myocytes and promotes apoptosis during myocardial ischemic injury.

miR-302a/b/c/d cooperatively inhibit BCRP expression to increase drug sensitivity in breast cancer cells

OBJECTIVE

BCRP is overexpressed in many tumors and mediates multidrug resistance in breast cancer. In this study, we determined the involvement of miR-302S in the development of drug resistance in breast cancer.

METHODS

The differential miRNA expression profiling in parental MCF-7 cells and its derivative mitoxantrone (MX)-resistant MCF-7 (MCF-7/MX) cells was determined by the microarray analysis. The levels of miR-302S family and BCRP mRNA expression were determined by using Quantitative Real-Time PCR. The targeting effect between the individuals of miR-302S and BCRP mRNA-3'UTR were detected by dual-luciferase reporter assay. Proteins of BCRP are represented by Western blot assay. Cell viability was assessed by MTS assay. Efflux capacity was evaluated using flow cytometry.

RESULTS

The miR-302S family including miR-302a, miR-302b, miR-302c, and miR-302d was significantly down-regulated in BCRP-overexpressing MCF-7/MX cells. Luciferase activity assay showed that miR-302 inhibited BCRP expression by targeting the 3'-untranslated region (UTR) of the BCRP mRNA. Overexpression of miR-302 increased intracellular accumulation of MX and sensitized breast cancer cells to MX. Furthermore, intratumoral injection of miR-302 potentiated the inhibitory effect of MX on tumor growth in mice transplanted with MCF-7/MX cells. Most importantly, miR-302S produced stronger effects than each individual member alone.

CONCLUSIONS

These findings suggest that miR-302 inhibits BCRP expression via targeting the 3'-UTR of BCRP mRNA. miR-302 members may cooperatively downregulate BCRP expression to increase chemosensitivity of breast cancer cells. miR-302 gene cluster may be a potential target for reversing BCRP-mediated chemoresistance in breast cancer.

microRNA expression changes after atrial fibrillation catheter ablation

Atrial fibrillation (AF) is most common arrhythmia in general population, with increasing trend in mortality and morbidity. Electrophysiological and structural abnormalities, promoting abnormal impulse formation and propagation, lead to this disease. AF catheter ablation is related to a not small percentage of nonresponder patients. microRNAs (miRs) have been used as AF fibrotic and electrical alterations biomarkers. miRs may differentiate responders patients to ablative approach. Selective miR target therapy, as upregulation by adenovirus transfection and/or miR downregulation by antagomiR, may be used to treat AF patients. Catheter ablation of triggering electrical pulmonary veins activity or fibrotic areas defragmentation may be upgraded by miR therapy to prevent cardiac electrical and fibrotic remodeling after AF ablation.

A regulatory loop containing miR-26a, GSK3β and C/EBPα regulates the osteogenesis of human adipose-derived mesenchymal stem cells

Elucidating the molecular mechanisms responsible for osteogenesis of human adipose-derived mesenchymal stem cells (hADSCs) will provide deeper insights into the regulatory mechanisms of this process and help develop more efficient methods for cell-based therapies. In this study, we analysed the role of miR-26a in the regulation of hADSC osteogenesis. The endogenous expression of miR-26a increased during the osteogenic differentiation. The overexpression of miR-26a promoted hADSC osteogenesis, whereas osteogenesis was repressed by miR-26a knockdown. Additionally, miR-26a directly targeted the 3′UTR of the GSK3β, suppressing the expression of GSK3β protein. Similar to the effect of overexpressing miR-26a, the knockdown of GSK3β promoted osteogenic differentiation, whereas GSK3β overexpression inhibited this process, suggesting that GSK3β acted as a negative regulator of hADSC osteogenesis. Furthermore, GSK3β influences Wnt signalling pathway by regulating β-catenin, and subsequently altered the expression of its downstream target C/EBPα. In turn, C/EBPα transcriptionally regulated the expression of miR-26a by physically binding to the CTDSPL promoter region. Taken together, our data identified a novel feedback regulatory circuitry composed of miR-26a, GSK3β and C/EBPα, the function of which might contribute to the regulation of hADSC osteogenesis. Our findings provided new insights into the function of miR-26a and the mechanisms underlying osteogenesis of hADSCs.

HDAC inhibitor misprocesses bantam oncomiRNA, but stimulates hid induced apoptotic pathway

Apoptosis or programmed cell death is critical for embryogenesis and tissue homeostasis. Uncontrolled apoptosis leads to different human disorders including immunodeficiency, autoimmune disorder and cancer. Several small molecules that control apoptosis have been identified. Here, we have shown the functional role of triazole derivative (DCPTN-PT) that acts as a potent HDAC inhibitor and mis-express proto onco microRNA (miRNA) bantam. To further understanding the mechanism of action of the molecule in apoptotic pathway, a series of experiments were also performed in Drosophila, a well known model organism in which the nature of human apoptosis is very analogous. DCPTN-PT mis processes bantam microRNA and alters its down regulatory target hid function and cleavage of Caspase-3 which in turn influence components of the mitochondrial apoptotic pathway in Drosophila. However regulatory microRNAs in other pro-apoptotic genes are not altered. Simultaneously, treatment of same molecule also affects the mitochondrial regulatory pathway in human tumour cell lines suggesting its conservative nature between fly and human. It is reasonable to propose that triazole derivative (DCPTN-PT) controls bantam oncomiRNA and increases hid induced apoptosis and is also able to influence mitochondrial apoptotic pathway.

In situ quantitation of intracellular microRNA in the whole cell cycle with a functionalized carbon nanosphere probe

A method was designed for in situ quantitation and monitoring of the change in intracellular microRNA in the whole cell cycle with a functionalized carbon nanosphere probe.

The role of microRNAs in bone remodeling

Bone remodeling is balanced by bone formation and bone resorption as well as by alterations in the quantities and functions of seed cells, leading to either the maintenance or deterioration of bone status. The existing evidence indicates that microRNAs (miRNAs), known as a family of short non-coding RNAs, are the key post-transcriptional repressors of gene expression, and growing numbers of novel miRNAs have been verified to play vital roles in the regulation of osteogenesis, osteoclastogenesis, and adipogenesis, revealing how they interact with signaling molecules to control these processes. This review summarizes the current knowledge of the roles of miRNAs in regulating bone remodeling as well as novel applications for miRNAs in biomaterials for therapeutic purposes.

Targeting MicroRNAs in Prevention and Treatment of Neurodegenerative Disorders

Preclinical Research microRNAs (miRNAs) are small noncoding RNAs (ncRNAs) that are key regulators of gene expression. They act on wide range of targets by binding to mRNA via imperfect complementarity at 3' UTR. Evidence suggests that miRNAs regulate many biological processes including neuronal development, differentiation, and disease. Altered expression of several miRNAs has been reported in many neurodegenerative disorders (NDDs). Many miRNAs are altered in these diseases, but miRNA 15, miRNA 21, and miRNA 146a have been shown to play critical role in many neurodegenerative conditions. As these miRNAs regulate many genes, miRNA targeted approaches would allow concurrently targeting of multiple effectors of pathways that regulate disease progression. In this review, we describe the role of miRNAs in various NDDs and their potential as therapeutic tools in prevention and treatment of neurological conditions.

miR-544a induces epithelial-mesenchymal transition through the activation of WNT signaling pathway in gastric cancer

The epithelial-mesenchymal transition (EMT) contributes to cancer progression, as well as the development of normal organs, wound healing and organ fibrosis. We established a cell-based reporter system for identifying EMT-inducing microRNAs (miRNAs) with a gastric cancer (GC) cell line, MKN1, transfected with a reporter construct containing a promoter sequence of VIM in the 5' upstream region of the TurboRFP reporter gene. Function-based screening using this reporter system was performed with a 328-miRNA library, and resulted in the identification miR-544a as an EMT-inducing miRNA. Although miR-544a is already known to be involved in the regulation of CDH1, the mechanism by which EMT occurs remains poorly understood. Herein, we demonstrated that overexpression of miR-544a induces VIM, SNAI1 and ZEB1 expression, and reduces CDH1 expression, resulting in an EMT phenotype. In addition, we found that CDH1 and AXIN2, which are related to the degradation and the translocation of β-catenin, are direct targets of miR-544a. Subsequently, the reduction of CDH1 and AXIN2 by miR-544a induced the nuclear import of β-catenin, suggesting that miR-544a may activate the WNT signaling pathway through the stabilization of β-catenin in nucleus. Our findings raise the possibility that inhibition of miR-544a may be a therapeutic target of metastatic GC.