Examination of artificial MiRNA mimics with centered-site complementarity for gene targeting

miR-135a inhibits the proliferation of HBV-infected hepatocellular carcinoma cells by targeting HOXA10

Background

The incidence of hepatocellular carcinoma (HCC) in patients with hepatitis B virus (HBV) is extremely high. MicroRNAs (miRNAs) are a type of endogenous non-coding small RNA with novel molecular therapeutic mechanisms that plays an important role in the occurrence and development of cancers. This study aimed to explore the regulation mechanism of miR-135a and HOXA10 in the proliferation, invasion, and apoptosis of HCC cells.

Methods

Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis was used to detect the expression level of miR-135a. Overexpression of miR-135a was used to measure the roles of miR-135a in the proliferation, invasion, and apoptosis of HCC cells. A dual luciferase experiment was performed to assess the relationship between HOXA10 and miR-135a. Western blot was applied to observe the protein levels of p-p38, p-ERK, and p-JNK.

Results

The expression levels of miR-135a were significantly decreased in HCC tissues and cells. Overexpression of miR-135a inhibited the proliferation and invasion but promoted the apoptosis of HCC cells. Importantly, our results confirmed that HOXA10 was a direct target of miR-135a. Under HBV infection, silencing of HOXA10 significantly blocked the proliferation and invasion and promoted the apoptosis of HCC cells. In addition, miR-135a/HOXA10 regulated the expressions of p-p38, p-ERK, and p-JNK through the miR-135a/HOXA10 axis, thereby inhibiting the activation of the MAPK pathway.

Conclusions

HBV promoted the proliferation and invasion, and inhibited the apoptosis of HCC cells by regulating the miR-135a/HOXA10 pathway. These findings provide a theoretical basis for improving the treatment of HBV-infected HCC patients.

In silico and in vitro analysis of the impact of single substitutions within EXO-motifs on Hsa-MiR-1246 intercellular transfer in breast cancer cell

MiR-1246 has recently gained much attention and many studies have shown its oncogenic role in colorectal, breast, lung, and ovarian cancers. However, miR-1246 processing, stability, and mechanisms directing miR-1246 into neighbor cells remain still unclear. In this study, we aimed to determine the role of single-nucleotide substitutions within short exosome sorting motifs - so-called EXO-motifs: GGAG and GCAG present in miR-1246 sequence on its intracellular stability and extracellular transfer. We applied in silico methods such as 2D and 3D structure analysis and modeling of protein interactions. We also performed in vitro validation through the transfection of fluorescently labeled miRNA to MDA-MB-231 cells, which we analyzed by flow cytometry and fluorescent microscopy. Our results suggest that nucleotides alterations that disturbed miR-1246 EXO-motifs were able to modulate miRNA-1246 stability and its transfer level to the neighboring cells, suggesting that the molecular mechanism of RNA stability and intercellular transfer can be closely related.

Plant RNA-mediated gene regulatory network

Not all transcribed RNAs are protein-coding RNAs. Many of them are non-protein-coding RNAs in diverse eukaryotes. However, some of them seem to be non-functional and are resulted from spurious transcription. A lot of non-protein-coding transcripts have a significant function in the translation process. Gene expressions depend on complex networks of diverse gene regulatory pathways. Several non-protein-coding RNAs regulate gene expression in a sequence-specific system either at the transcriptional level or post-transcriptional level. They include a significant part of the gene expression regulatory network. RNA-mediated gene regulation machinery is evolutionarily ancient. They well-evolved during the evolutionary time and are becoming much more complex than had been expected. In this review, we are trying to summarizing the current knowledge in the field of RNA-mediated gene silencing.

Disabling VEGF-Response of Purkinje Cells by Downregulation of KDR via miRNA-204-5p

The vascular endothelial growth factor (VEGF) is well known for its wide-ranging functions, not only in the vascular system, but also in the central (CNS) and peripheral nervous system (PNS). To study the role of VEGF in neuronal protection, growth and maturation processes have recently attracted much interest. These effects are mainly mediated by VEGF receptor 2 (VEGFR-2). Current studies have shown the age-dependent expression of VEGFR-2 in Purkinje cells (PC), promoting dendritogenesis in neonatal, but not in mature stages. We hypothesize that microRNAs (miRNA/miR) might be involved in the regulation of VEGFR-2 expression during the development of PC. In preliminary studies, we performed a miRNA profiling and identified miR204-5p as a potential regulator of VEGFR-2 expression. In the recent study, organotypic slice cultures of rat cerebella (postnatal day (p) 1 and 9) were cultivated and VEGFR-2 expression in PC was verified via immunohistochemistry. Additionally, PC at age p9 and p30 were isolated from cryosections by laser microdissection (LMD) to analyse VEGFR-2 expression by quantitative RT-PCR. To investigate the influence of miR204-5p on VEGFR-2 levels in PC, synthetic constructs including short hairpin (sh)-miR204-5p cassettes (miRNA-mimics), were microinjected into PC. The effects were analysed by confocal laser scanning microscopy (CLSM) and morphometric analysis. For the first time, we could show that miR204-5p has a negative effect on VEGF sensitivity in juvenile PC, resulting in a significant decrease of dendritic growth compared to untreated juvenile PC. In mature PC, the overexpression of miR204-5p leads to a shrinkage of dendrites despite VEGF treatment. The results of this study illustrate, for the first time, which miR204-5p expression has the potential to play a key role in cerebellar development by inhibiting VEGFR-2 expression in PC.

MicroRNA-766-3p Contributes to Anti-Inflammatory Responses through the Indirect Inhibition of NF-κB Signaling

MicroRNA (miRNA) is small RNA of 20 to 22 nucleotides in length and is stably present in plasma. Regulating the expression of miRNA taken into cells has been suggested as a general therapeutic approach. We identified the novel anti-inflammatory miRNA hsa-miR-766-3p and investigated its biological function in human rheumatoid arthritis (RA) fibroblast-like synoviocyte MH7A cells. To verify the function of the miRNA present in the plasma of RA patients, we performed a comprehensive analysis of the miRNA expression during abatacept treatment and identified eight miRNAs with significantly altered expression levels. Among these eight miRNAs, miR-766-3p was found to have a clear function. The expression of inflammatory genes in response to inflammatory stimuli was suppressed in MH7A transduced with miR-766-3p. We showed that miR-766-3p indirectly reduced the activation of NF-κB and clarified that this mechanism was partially involved in the reduction of the mineralocorticoid receptor expression. In addition, the inflammatory responses were suppressed in other types of cells. These results indicate the novel function of miR-766-3p, findings that may aid in the development of therapies to suppress inflammation, not only in RA but also in other diseases.

Foxo3a-mediated overexpression of microRNA-622 suppresses tumor metastasis by repressing hypoxia-inducible factor-1α in ERK-responsive lung cancer

Metastatic spread of cancer cells portends a poor prognosis and mortality for lung cancer patients. Hypoxia-inducible factor-1α (HIF-1α) enhances tumor cell motility by activating the epithelial-to-mesenchymal transition (EMT), which is considered a prerequisite for metastasis. Recent studies of microRNA involvement in cancer invasion and metastasis have highlighted the role of such RNAs in tumor development. However, little work has been done to identify tumor suppressor microRNAs that target HIF-1α to down-modulate the EMT and thereby counteract the aggressiveness and metastasis of lung cancer cells. Here, we identified the 3'-untranslated region of HIF-1α mRNA as a target of miR-622 and established that miR-622-mediated down-modulation of HIF-1α correlates with decreased levels of mesenchymal proteins, including Snail, β-catenin, and vimentin. Functional analyses revealed that increased miR-622 expression inhibited lung cancer cell migration and invasion in vitro. miR-622 also inhibited the genesis of metastatic lung nodules as demonstrated in a lung cancer xenograft model in which nude mice were transplanted with A549 cells expressing miR-622. Mechanistic analyses showed that overexpression of EGF decreased the miR-622 level in A549 cells, and this reduction could be rescued by administrating U0126, an inhibitor of ERK. Moreover, miR-622 overexpression mediated by the transcription factor FOXO3a decreased the invasiveness of lung tumor cells by inhibiting HIF-1α via inactivation of ERK signaling in U0126-treated A549 cells. These findings highlight the pivotal role of the FOXO3a/miR-622 axis in inhibiting HIF-1α to interfere with tumor metastasis, and this information may contribute to development of novel therapeutic strategies for treating aggressive lung cancer.

Noncoding RNA as regulators of cardiac fibrosis: current insight and the road ahead

Cardiac fibrosis is an important pathological feature of cardiac remodeling in heart diseases. The molecular mechanisms of cardiac fibrosis are unknown. Genomic analyses estimated that many noncoding DNA regions generate noncoding RNAs (ncRNAs). ncRNAs have emerged as key molecular players in the regulation of gene expression in different biological processes. Recent studies have started to reveal the importance of ncRNAs in heart development and suggest also an involvement in cardiac fibrosis. These molecules are emerging as important regulators of cellular process. Here, we review particularly focuses on the involvement of two large families of ncRNAs, namely microRNAs (miRNAs) and long noncoding RNAs (LncRNAs) in the regulation of cardiac fibrosis. Furthermore, we review the functions and role of ncRNAs in cardiac biology and discuss these reports and the therapeutic potential of ncRNAs for cardiac fibrosis associated with fibroblast activation and proliferation.

Artificial microRNA mediated gene silencing in plants: progress and perspectives

Homology based gene silencing has emerged as a convenient approach for repressing expression of genes in order to study their functions. For this purpose, several antisense or small interfering RNA based gene silencing techniques have been frequently employed in plant research. Artificial microRNAs (amiRNAs) mediated gene silencing represents one of such techniques which can utilize as a potential tool in functional genomics. Similar to microRNAs, amiRNAs are single-stranded, approximately 21 nt long, and designed by replacing the mature miRNA sequences of duplex within pre-miRNAs. These amiRNAs are processed via small RNA biogenesis and silencing machinery and deregulate target expression. Holding to various refinements, amiRNA technology offers several advantages over other gene silencing methods. This is a powerful and robust tool, and could be applied to unravel new insight of metabolic pathways and gene functions across the various disciplines as well as in translating observations for improving favourable traits in plants. This review highlights general background of small RNAs, improvements made in RNAi based gene silencing, implications of amiRNA in gene silencing, and describes future themes for improving value of this technology in plant science.