The therapeutic potential of microRNAs: disease modulators and drug targets

microRNA-106b-5p and Rab10: Potential Markers of Acute Myeloid Leukemia

This study focuses on acute myeloid leukemia (AML), a condition with a 5-year survival rate below 30% despite various treatment options. Recent strides in targeted therapies have shown promise, leading to better outcomes with minimal toxicity. These advances underscore the importance of discovering new diagnostic and prognostic targets for AML. In this context, the authors investigated the expression of microRNA-106b-5p (miR-106b-5p), Rab10 mRNA, and Rab10 proteins in peripheral blood and bone marrow (BM) samples from both healthy individuals and AML patients at different stages of the disease (initial diagnosis, recurrence, and complete remission). This examination aimed to identify potential biomarkers for AML diagnosis, treatment, and prognosis. From June 2021 to December 2022, they collected 100 BM and peripheral blood samples. The relative expression of miR-106b-5p and Rab10 mRNA in the BM of AML patients was measured using Real-time polymerase chain reaction (qRT-PCR), while the relative expression of Rab10 protein in serum was determined using the ELISA method. The chromosomal karyotype of initially diagnosed patients was analyzed using the R tape. The qRT-PCR results revealed that the expression of miR-106b-5p and Rab10 mRNA were significantly higher in patients at initial diagnosis and recurrence compared with healthy individuals and those in complete remission (p < 0.001). They observed a significant reduction in the expression of miR-106b-5p, Rab10 mRNA, and Rab10 protein in the BM and peripheral blood of patients during complete remission (p < 0.05), as demonstrated by dynamic monitoring of five patients in the initial group. Furthermore, they found a close association between the expression of miR-106b-5p and the number of white blood cells at the initial diagnosis in AML patients (p < 0.05). Spearman correlation analysis revealed a positive correlation among miR-106b-5p, Rab10 mRNA, and Rab10 proteins (p < 0.05). The diagnostic potential of miR-106b-5p and Rab10 proteins was underscored by Receiver Operating Characteristic (ROC) curve analysis, which demonstrated their high accuracy in AML diagnosis (AUC: 0.944 and 0.853, respectively; p < 0.0001). Additionally, Kaplan-Meier survival analysis suggested that lower expression of these markers was associated with better prognoses (p < 0.05). In summary, their findings propose miR-106b-5p and Rab10 proteins as promising biomarkers for AML, offering insights for diagnosis, treatment, and prognosis.

MicroRNAs: Midfielders of Cardiac Health, Disease and Treatment

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules that play a role in post-transcriptional gene regulation. It is generally accepted that their main mechanism of action is the negative regulation of gene expression, through binding to specific regions in messenger RNA (mRNA) and repressing protein translation. By interrupting protein synthesis, miRNAs can effectively turn genes off and influence many basic processes in the body, such as developmental and apoptotic behaviours of cells and cardiac organogenesis. Their importance is highlighted by inhibiting or overexpressing certain miRNAs, which will be discussed in the context of coronary artery disease, atrial fibrillation, bradycardia, and heart failure. Dysregulated levels of miRNAs in the body can exacerbate or alleviate existing disease, and their omnipresence in the body makes them reliable as quantifiable markers of disease. This review aims to provide a summary of miRNAs as biomarkers and their interactions with targets that affect cardiac health, and intersperse it with current therapeutic knowledge. It intends to succinctly inform on these topics and guide readers toward more comprehensive works if they wish to explore further through a wide-ranging citation list.

Role of miRNAs in Neurodegeneration: From Disease Cause to Tools of Biomarker Discovery and Therapeutics

Neurodegenerative diseases originate from neuronal loss in the central nervous system (CNS). These debilitating diseases progress with age and have become common due to an increase in longevity. The National Institute of Environmental Health Science’s 2021 annual report suggests around 6.2 million Americans are living with Alzheimer’s disease, and there is a possibility that there will be 1.2 million Parkinson’s disease patients in the USA by 2030. There is no clear-cut universal mechanism for identifying neurodegenerative diseases, and therefore, they pose a challenge for neurobiology scientists. Genetic and environmental factors modulate these diseases leading to familial or sporadic forms. Prior studies have shown that miRNA levels are altered during the course of the disease, thereby suggesting that these noncoding RNAs may be the contributing factor in neurodegeneration. In this review, we highlight the role of miRNAs in the pathogenesis of neurodegenerative diseases. Through this review, we aim to achieve four main objectives: First, we highlight how dysregulation of miRNA biogenesis led to these diseases. Second, we highlight the computational or bioinformatics tools required to identify the putative molecular targets of miRNAs, leading to biological molecular pathways or mechanisms involved in these diseases. Third, we focus on the dysregulation of miRNAs and their target genes leading to several neurodegenerative diseases. In the final section, we highlight the use of miRNAs as potential diagnostic biomarkers in the early asymptomatic preclinical diagnosis of these age-dependent debilitating diseases. Additionally, we discuss the challenges and advances in the development of miRNA therapeutics for brain targeting. We list some of the innovative strategies employed to deliver miRNA into target cells and the relevance of these viral and non-viral carrier systems in RNA therapy for neurodegenerative diseases. In summary, this review highlights the relevance of studying brain-enriched miRNAs, the mechanisms underlying their regulation of target gene expression, their dysregulation leading to progressive neurodegeneration, and their potential for biomarker marker and therapeutic intervention. This review thereby highlights ways for the effective diagnosis and prevention of these neurodegenerative disorders in the near future.

Opportunities Offered by Graphene Nanoparticles for MicroRNAs Delivery for Amyotrophic Lateral Sclerosis Treatment

Amyotrophic lateral sclerosis (ALS) is characterized by the degeneration and death of motor neurons. This neurodegenerative disease leads to muscle atrophy, paralysis, and death due to respiratory failure. MicroRNAs (miRNAs) are small non-coding ribonucleic acids (RNAs) with a length of 19 to 25 nucleotides, participating in the regulation of gene expression. Different studies have demonstrated that miRNAs deregulation is critical for the onset of a considerable number of neurodegenerative diseases, including ALS. Some studies have underlined how miRNAs are deregulated in ALS patients and for this reason, design therapies are used to correct the aberrant expression of miRNAs. With this rationale, delivery systems can be designed to target specific miRNAs. Specifically, these systems can be derived from viral vectors (viral systems) or synthetic or natural materials, including exosomes, lipids, and polymers. Between many materials used for non-viral vectors production, the two-dimensional graphene and its derivatives represent a good alternative for efficiently delivering nucleic acids. The large surface-to-volume ratio and ability to penetrate cell membranes are among the advantages of graphene. This review focuses on the specific pathogenesis of miRNAs in ALS and on graphene delivery systems designed for gene delivery to create a primer for future studies in the field.

MicroRNA-217: a therapeutic and diagnostic tumor marker

INTRODUCTION

Cancer as one of the most common causes of death has always been one of the major health challenges globally. Since, the identification of tumors in the early tumor stages can significantly reduce mortality rates; it is required to introduce novel early detection tumor markers. MicroRNAs (miRNAs) have pivotal roles in regulation of cell proliferation, migration, apoptosis, and tumor progression. Moreover, due to the higher stability of miRNAs than mRNAs in body fluids, they can be considered as non-invasive diagnostic or prognostic markers in cancer patients.

AREAS COVERED

In the present review we have summarized the role of miR-217 during tumor progressions. The miR-217 functions were categorized based on its target molecular mechanisms and signaling pathways.

EXPERT OPINION

It was observed that miR-217 mainly exerts its function by regulation of the transcription factors during tumor progressions. The WNT, MAPK, and PI3K/AKT signaling pathways were also important molecular targets of miR-217 in different cancers. The present review clarifies the molecular biology of miR-217 and paves the way of introducing miR-217 as a non-invasive diagnostic marker and therapeutic target in cancer therapy.

MicroRNAs as the critical regulators of cisplatin resistance in gastric tumor cells

Combined chemotherapeutic treatment is the method of choice for advanced and metastatic gastric tumors. However, resistance to chemotherapeutic agents is one of the main challenges for the efficient gastric cancer (GC) treatment. Cisplatin (CDDP) is used as an important regimen of chemotherapy for GC which induces cytotoxicity by interfering with DNA replication in cancer cells and inducing their apoptosis. Majority of patients experience cisplatin-resistance which is correlated with tumor metastasis and relapse. Moreover, prolonged and high-dose cisplatin administrations cause serious side effects such as nephrotoxicity, ototoxicity, and anemia. Since, there is a high rate of recurrence after CDDP treatment in GC patients; it is required to clarify the molecular mechanisms associated with CDDP resistance to introduce novel therapeutic methods. There are various cell and molecular processes associated with multidrug resistance (MDR) including drug efflux, detoxification, DNA repair ability, apoptosis alteration, signaling pathways, and epithelial-mesenchymal transition (EMT). MicroRNAs are a class of endogenous non-coding RNAs involved in chemo resistance of GC cells through regulation of all of the MDR mechanisms. In present review we have summarized all of the miRNAs associated with cisplatin resistance based on their target genes and molecular mechanisms in gastric tumor cells. This review paves the way of introducing a miRNA-based panel of prognostic markers to improve the efficacy of chemotherapy and clinical outcomes in GC patients. It was observed that miRNAs are mainly involved in cisplatin response of gastric tumor cells via regulation of signaling pathways, autophagy, and apoptosis.

Highly Potent GalNAc-Conjugated Tiny LNA Anti-miRNA-122 Antisense Oligonucleotides

The development of clinically relevant anti-microRNA antisense oligonucleotides (anti-miRNA ASOs) remains a major challenge. One promising configuration of anti-miRNA ASOs called "tiny LNA (tiny Locked Nucleic Acid)" is an unusually small (~8-mer), highly chemically modified anti-miRNA ASO with high activity and specificity. Within this platform, we achieved a great enhancement of the in vivo activity of miRNA-122-targeting tiny LNA by developing a series of N-acetylgalactosamine (GalNAc)-conjugated tiny LNAs. Specifically, the median effective dose (ED50) of the most potent construct, tL-5G3, was estimated to be ~12 nmol/kg, which is ~300-500 times more potent than the original unconjugated tiny LNA. Through in vivo/ex vivo imaging studies, we have confirmed that the major advantage of GalNAc over tiny LNAs can be ascribed to the improvement of their originally poor pharmacokinetics. We also showed that the GalNAc ligand should be introduced into its 5' terminus rather than its 3' end via a biolabile phosphodiester bond. This result suggests that tiny LNA can unexpectedly be recognized by endogenous nucleases and is required to be digested to liberate the parent tiny LNA at an appropriate time in the body. We believe that our strategy will pave the way for the clinical application of miRNA-targeting small ASO therapy.

MicroRNAs in Rectal Cancer: Functional Significance and Promising Therapeutic Value

It is well-known that microRNAs (miRNAs) are critical mediators of initiation and disease progression in many human cancers. Rectal cancer is a highly prevalent tumor, accounting for around one third of newly diagnosed colorectal cancers. The usefulness of miRNAs as clinical biomarkers predictive of the outcome and response to chemoradiotherapy has been well-reported for rectal cancer. However, the existing literature on their functional and therapeutic impact needs to be put in context to clarify their role in disease pathogenesis. Therfore, this review is focused on the functional relevance of miRNAs as key regulators of signaling pathways in rectal cancer and their potential therapeutic value as novel molecular targets in this disease.

MicroRNA Nanotherapeutics for Lung Targeting. Insights into Pulmonary Hypertension

In this review, the potential future role of microRNA-based therapies and their specific application in lung diseases is reported with special attention to pulmonary hypertension. Current limitations of these therapies will be pointed out in order to address the challenges that they need to face to reach clinical applications. In this context, the encapsulation of microRNA-based therapies in nanovectors has shown improvements as compared to chemically modified microRNAs toward enhanced stability, efficacy, reduced side effects, and local administration. All these concepts will contextualize in this review the recent achievements and expectations reported for the treatment of pulmonary hypertension.

Engineered Circular RNA Sponges Act as miRNA Inhibitors to Attenuate Pressure Overload-Induced Cardiac Hypertrophy

Circular RNAs (circRNAs) sequester microRNAs (miRNAs) and repress their endogenous activity. We hypothesized that artificial circRNA sponges (circmiRs) can be constructed to target miRNAs therapeutically, with a low dosage requirement and extended half-lives compared to current alternatives. This could present a new treatment approach for critical global pathologies, including cardiovascular disease. Here, we constructed a circmiR sponge to target known cardiac pro-hypertrophic miR-132 and -212. Expressed circmiRs competitively inhibited miR-132 and -212 activity in luciferase rescue assays and showed greater stability than linear sponges. A design containing 12 bulged binding sites with 12 nucleotides spacing was determined to be optimal. Adeno-associated viruses (AAVs) were used to deliver circmiRs to cardiomyocytes in vivo in a transverse aortic constriction (TAC) mouse model of cardiac disease. Hypertrophic disease characteristics were attenuated, and cardiac function was preserved in treated mice, demonstrating the potential of circmiRs as novel therapeutic tools. Subsequently, group I permutated intron-exon sequences were used to directly synthesize exogenous circmiRs, which showed greater in vitro efficacy than the current gold standard antagomiRs in inhibiting miRNA function. Engineered circRNAs thus offer exciting potential as future therapeutics.

Hydrophobically Modified let-7b miRNA Enhances Biodistribution to NSCLC and Downregulates HMGA2 In Vivo

MicroRNAs (miRNAs) have increasingly been shown to be involved in human cancer, and interest has grown about the potential use of miRNAs for cancer therapy. miRNA levels are known to be altered in cancer cells, including in non-small cell lung cancer (NSCLC), a subtype of lung cancer that is the most prevalent form of cancer worldwide and that lacks effective therapies. The let-7 miRNA is involved in the regulation of oncogene expression in cells and directly represses cancer growth in the lung. let-7 is therefore a potential molecular target for tumor therapy. However, applications of RNA interference for cancer research have been limited by a lack of simple and efficient methods to deliver oligonucleotides (ONs) to cancer cells. In this study, we have used in vitro and in vivo approaches to show that HCC827 cells internalize hydrophobically modified let-7b miRNAs (hmiRNAs) added directly to the culture medium without the need for lipid formulation. We identified functional let-7b hmiRNAs targeting the HMGA2 mRNA, one of the let-7 target genes upregulated in NSCLC, and show that direct uptake in HCC827 cells induced potent and specific gene silencing in vitro and in vivo. Thus, hmiRNAs constitute a novel class of ONs that enable functional studies of genes involved in cancer biology and are potentially therapeutic molecules.

MicroRNAs: pivotal regulators in acute myeloid leukemia

MicroRNAs are a class of small non-coding RNAs that are 19-22 nucleotides in length and regulate a variety of biological processes at the post-transcriptional level. MicroRNA dysregulation disrupts normal biological processes, resulting in tumorigenesis. Acute myeloid leukemia is an invasive hematological malignancy characterized by the abnormal proliferation and differentiation of immature myeloid cells. Due to the low 5-year survival rate, there is an urgent need to discover novel diagnostic markers and therapeutic targets. In recent years, microRNAs have been shown to play important roles in hematological malignancies by acting as tumor suppressors and oncogenes. MicroRNAs have the potential to be a breakthrough in the diagnosis and treatment of acute myeloid leukemia. In this review, we summarize the biology of microRNAs and discuss the relationships between microRNA dysregulation and acute myeloid leukemia in the following aspects: signaling pathways, the abnormal biological behavior of acute myeloid leukemia cells, the clinical application of microRNAs and competing endogenous RNA regulatory networks.

The Role of Long Noncoding RNAs in the Biology of Pituitary Adenomas

Long noncoding RNAs (lncRNAs) are a large group of noncoding RNAs 200 nucleotides long. lncRNAs that function as regulatory factors have been identified for several complex cellular processes, such as cell death, growth, differentiation, apoptosis, epigenetic regulation, and so on. Many lncRNAs have altered expression and are likely to play a functional role in oncogenesis. The pituitary adenoma is the second most common intracranial tumor. Despite this situation, the molecular mechanism of pituitary adenoma formation has not yet been fully identified. This review summarizes recent progress in the study of lncRNAs on the pathogenesis of pituitary tumors. We cover the latest results associated with this role and highlight the therapeutic possibilities for pituitary adenomas.

The MicroRNA-551a/MEF2C Axis Regulates the Survival and Sphere Formation of Cancer Cells in Response to 5-Fluorouracil

microRNAs regulate a diverse spectrum of cancer biology, including tumorigenesis, metastasis, stemness, and drug resistance. To investigate miRNA-mediated regulation of drug resistance, we characterized the resistant cell lines to 5-fluorouracil by inducing stable expression of miRNAs using lenti-miRNA library. Here, we demonstrate miR-551a as a novel factor regulating cell survival after 5-FU treatment. miR-551a-expressing cells (Hep3B-lenti-miR-551a) were resistant to 5-FU-induced cell death, and after 5-FU treatment, and showed significant increases in cell viability, cell survival, and sphere formation. It was further shown that myocyte-specific factor 2C is the direct target of miR-551a. Our results suggest that miR-551a plays a novel function in regulating 5-FU-induced cell death, and targeting miR-551a might be helpful to sensitize cells to anti-cancer drugs.

The microRNA miR-7a-5p ameliorates ischemic brain damage by repressing α-synuclein

Ischemic stroke, which is caused by a clot that blocks blood flow to the brain, can be severely disabling and sometimes fatal. We previously showed that transient focal ischemia in a rat model induces extensive temporal changes in the expression of cerebral microRNAs, with a sustained decrease in the abundance of miR-7a-5p (miR-7). Here, we evaluated the therapeutic efficacy of a miR-7 mimic oligonucleotide after cerebral ischemia in rodents according to the Stroke Treatment Academic Industry Roundtable (STAIR) criteria. Rodents were injected locally or systemically with miR-7 mimic before or after transient middle cerebral artery occlusion. Decreased miR-7 expression was observed in both young and aged rats of both sexes after cerebral ischemia. Pre- or postischemic treatment with miR-7 mimic decreased the lesion volume in both sexes and ages studied. Furthermore, systemic injection of miR-7 mimic into mice at 30 min (but not 2 hours) after cerebral ischemia substantially decreased the lesion volume and improved motor and cognitive functional recovery with minimal peripheral toxicity. The miR-7 mimic treatment substantially reduced the postischemic induction of α-synuclein (α-Syn), a protein that induces mitochondrial fragmentation, oxidative stress, and autophagy that promote neuronal cell death. Deletion of the gene encoding α-Syn abolished miR-7 mimic-dependent neuroprotection and functional recovery in young male mice. Further analysis confirmed that the transcript encoding α-Syn was bound and repressed by miR-7. Our findings suggest that miR-7 mimics may therapeutically minimize stroke-induced brain damage and disability.

MicroRNAs as New Biomarkers for Diagnosis and Prognosis, and as Potential Therapeutic Targets in Acute Myeloid Leukemia

Acute myeloid leukemias (AML) are clonal disorders of hematopoietic progenitor cells which are characterized by relevant heterogeneity in terms of phenotypic, genotypic, and clinical features. Among the genetic aberrations that control disease development there are microRNAs (miRNAs). miRNAs are small non-coding RNAs that regulate, at post-transcriptional level, translation and stability of mRNAs. It is now established that deregulated miRNA expression is a prominent feature in AML. Functional studies have shown that miRNAs play an important role in AML pathogenesis and miRNA expression signatures are associated with chemotherapy response and clinical outcome. In this review we summarized miRNA signature in AML with different cytogenetic, molecular and clinical characteristics. Moreover, we reviewed the miRNA regulatory network in AML pathogenesis and we discussed the potential use of cellular and circulating miRNAs as biomarkers for diagnosis and prognosis and as therapeutic targets.

Improved microRNA suppression by WPRE-linked tough decoy microRNA sponges

Our genes are post-transcriptionally regulated by microRNAs (miRNAs) inducing translational suppression and degradation of targeted mRNAs. Strategies to inhibit miRNAs in a spatiotemporal manner in a desired cell type or tissue, or at a desired developmental stage, can be crucial for understanding miRNA function and for pushing forward miRNA suppression as a feasible rationale for genetic treatment of disease. For such purposes, RNA polymerase II (RNA Pol II)-transcribed tough decoy (TuD) miRNA inhibitors are particularly attractive. Here, we demonstrate augmented miRNA suppression capacity of TuD RNA hairpins linked to the Woodchuck hepatitis virus post-transcriptional regulatory element (WPRE). This effect is position-dependent and evident only when the WPRE is positioned upstream of the TuD. In accordance, inclusion of the WPRE does not change nuclear export, translation, total levels of TuD-containing RNA transcripts, or cytoplasmic P-body localization, suggesting that previously reported WPRE functions are negligible for improved TuD function. Notably, deletion analysis of TuD-fused WPRE unveils truncated WPRE variants resulting in optimized miRNA suppression. Together, our findings add to the guidelines for production of WPRE-supported anti-miRNA TuDs.

Isoliquiritigenin attenuates MiR-21 expression via induction of PIAS3 in breast cancer cells

Activated STAT3 triggered miR-21 transcription via binding to its promoter. ISL induced PIAS3 expression, a specific inhibitor of activated STAT3, leading to inhibition of STAT3 signaling and subsequent miR-21 transcription in breast cancer cells.

Current progress on microRNAs-based therapeutics in neurodegenerative diseases

MicroRNAs (miRNAs)-based therapy has recently emerged as a promising strategy in the treatments of neurodegenerative diseases. Thus, in this review, the most recent and important challenges and advances on the development of miRNA therapeutics for brain targeting are discussed. In particular, this review highlights current knowledge and progress in the field of manufacturing, recovery, isolation, purification, and analysis of these therapeutic oligonucleotides. Finally, the available miRNA delivery systems are reviewed and an analysis is presented in what concerns to the current challenges that have to be addressed to ensure their specificity and efficacy. Overall, it is intended to provide a perspective on the future of miRNA-based therapeutics, focusing the biotechnological approach to obtain miRNAs. WIREs RNA 2017, 8:e1409. doi: 10.1002/wrna.1409 For further resources related to this article, please visit the WIREs website.

Reprogramming macrophage orientation by microRNA 146b targeting transcription factor IRF5

The regulation of macrophage orientation pathological conditions is important but still incompletely understood. Here, we show that IL-10 and Rag1 double knockout mice spontaneously develop colitis with dominant M1 macrophage phenotype, suggesting that IL-10 regulates macrophage orientation in inflammation. We demonstrate that IL-10 stimulation induced miR-146b expression, and that the expression of miR-146b was impaired in IL-10 deficient macrophages. Our data show that miR-146b targets IRF5, resulting in the regulation of macrophage activation. Furthermore, miR-146b deficient mice developed intestinal inflammation with enhanced M1 macrophage polarization. Finally, miR-146b mimic treatment significantly suppresses M1 macrophage activation and ameliorates colitis development in vivo. Collectively, the results suggest that IL-10 dependent miR-146b plays an important role in the modulation of M1 macrophage orientation.

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Interleukin 10-induced miR-146b plays a critical role in the regulation of macrophage polarization and colitis development by targeting IRF5.

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Treatment with miR-146b mimic significantly suppresses M1 macrophage activation and ameliorates colitis development.

Interleukin 10 and Interleukin receptor are clearly involved in the development of inflammatory bowel diseases and other inflammatory diseases. Notably, the mutation of Interleukin 10 and Interleukin 10 receptor are clearly correlated with inflammatory bowel diseases. In the present study we show that Interleukin 10-induced miR-146b plays a critical role in the regulation of macrophage polarization and colitis development by targeting IRF5. Treatment with miR-146b mimic significantly suppresses M1 macrophage activation and ameliorates colitis development. The results highlight the potent role of miR146b in the control of immune responses and pathogenesis of inflammatory diseases.

Potential relevance of microRNAs in inter-species epigenetic communication, and implications for disease pathogenesis

MicroRNAs are short non-protein coding RNA molecules involved in the epigenetic regulation of gene expression. Recently, extracellular microRNAs have been described in body fluids that might enable epigenetic communication between distant tissues. Being highly conserved molecules, exogenous xeno-microRNAs from different species could affect gene expression in the host even in a cross-kingdom fashion. Several data underline the relevance of microRNA-mediated communication between virus and host, and there are some experimental data showing that plant- or animal-derived dietary microRNAs might have gene expression modulating activity in humans. Milk-derived microRNAs might be involved in the "epigenetic priming" of the baby. Exogenous microRNAs might be hypothesized to be implicated in disease pathogenesis, e.g. in tumors. Major questions remain to be addressed including the amount of xeno-microRNAs needed for biological action or routes for microRNA delivery. In this brief review, experimental data and hypotheses on the potential pathogenic inter-species relevance of microRNA are presented.

MicroRNA-150 upregulation reduces osteosarcoma cell invasion and metastasis by downregulating Ezrin

The present study aimed to investigate the effect of microRNA-150 (miRNA/miR-150) in osteosarcoma (OS) cell invasion and metastasis by the regulation of Ezrin. To compare the differences in the expression of miR-150 and Ezrin, cell models of OS metastasis were established by exogenous transfection of miR-150 on the basis of different expression levels of miR-150. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to estimate these expression levels. Ezrin expression was detected by western blot assay. Methylthiazolyldiphenyl-tetrazolium bromide assay was performed to determine cells proliferation. Cell invasion and migration were measured in vitro by Transwell migration assays. Detection of apoptosis adopted flow cytometry. The results of RT-qPCR showed that the miR-150 expression in OS F5M2 cells was significantly increased following exogenous transfection of miR-150 mimics, and the expression of miR-150 was positively correlated with the concentration of the miR-150 mimics. Western blot assay indicated that the Ezrin expression in the F5M2 cells was decreased with the exogenous overexpression of miR-150. Additionally, Transwell assays revealed that the overexpression of miR-150 significantly suppressed the invasion and metastasis ability of the F5M2 cells. miR-150 upregulation may reduce OS cell invasion and metastasis by downregulating the expression of Ezrin.

Role of microRNA-210 in human intervertebral disc degeneration

The present study aimed to investigate the role of microRNA (miR)-210 in the development of intervertebral disc degeneration (IDD). Human nucleus pulposus (NP) samples were collected from patients with scoliosis and IDD (n=12 each) as the scoliosis control and IDD groups, respectively. The expression levels of miR-210 were detected using reverse-transcription quantitative polymerase chain reaction. In vitro overexpression and knockdown of miR-210 in human NP cells were achieved by transfection of NP cells with lentiviral pre-miR-210 and antagomiR-210, respectively. The protein expression levels of homeobox A9 (HOXA9) were then detected in NP cells with modulated miR-210 using western blot analysis. Flow cytometry with allophycocyanin-Annexin V/7 and 7-aminoactinomycin D staining was also used to detect the proportion of NP cells with modulated miR-210 undergoing apoptosis. The current study revealed that the miR-210 expression was decreased in patients with IDD compared with that of the scoliosis control group (P<0.05). Furthermore, the upregulation of miR-210 with pre-miR-210 led to the repression of HOXA9. The HOXA9 level was significantly lower in these cells compared with that of NP cells treated with a corresponding negative sequence (P<0.05). Knockdown of miR-210 with antagomiR-210 resulted in upregulation of HOXA9 in NP cells, determined as the level of HOXA9 was significantly higher than that of NP cells treated with a negative sequence (P<0.05). The proportion of apoptotic NP cells also significantly decreased following treatment with pre-miR-210 compared with the scoliosis control group (12.1±1.43 vs. 23.8±1.22%, respectively; P<0.05). In conclusion, downregulation of miR-210 may promote Fas-mediated apoptosis in human IDD by regulating the expression of HOXA9. This indicates that miR-210 may be closely associated with the development of IDD and may act as a novel target in IDD treatment.

Dietary components as epigenetic-regulating agents against cancer

Carcinogenesis is a complicated process that involves the deregulation of epigenetics resulting in cellular transformational events, such proliferation, differentiation, and metastasis. Epigenetic machinery changes the accessibility of chromatin to transcriptional regulation through DNA modification. The collaboration of epigenetics and gene transcriptional regulation creates a suitable microenvironment for cancer development, which is proved by the alternation in cell proliferation, differentiation, division, metabolism, DNA repair and movement. Therefore, the reverse of epigenetic dysfunction may provide a possible strategy and new therapeutic targets for cancer treatment. Many dietary components such as sulforaphane and epigallocatechin- 3-gallate have been demonstrated to exert chemopreventive influences, such as reducing tumor growth and enhancing cancer cell death. Anticancer mechanistic studies also indicated that dietary components could display the ability to reverse epigenetic deregulation in assorted tumors via reverting the adverse epigenetic regulation, including alternation of DNA methylation and histone modification, and modulation of microRNA expression. Therefore, dietary components as therapeutic agents on epigenetics becomes an attractive approach for cancer prevention and intervention at the moment. In this review, we summarize the recent discoveries and underlying mechanisms of the most common dietary components for cancer prevention via epigenetic regulation.

Suggested roles for microRNA in tumors

MicroRNAs are short non-coding RNA molecules encoded by distinct genes involved in the posttranscriptional regulation of gene expression. Forming part of the epigenetic machinery, microRNAs are involved in several aspects of tumorigenesis. Deregulation of microRNA expression is a common feature of tumors. Overexpressed oncogenic and underexpressed tumor suppressor microRNAs have been described in many different tumors. MicroRNAs are released from tumors that might affect other cells within and outside the tumor. Circulating microRNAs might also be involved in a tumor surveillance mechanism. In this short overview, some important aspects of microRNA in tumors are discussed.

MiR-362-5p promotes the malignancy of chronic myelocytic leukaemia via down-regulation of GADD45α

Background

MicroRNAs (miR, miRNAs) play pivotal roles in numerous physiological and pathophysiological contexts. We investigated whether miR-362-5p act as an oncogene in chronic myeloid leukaemia (CML) and aimed to understand its potential underlying mechanisms.

Methods

We compared the miR-362-5p expression levels between CML and non-CML cell lines, and between fresh blood samples from CML patients and normal healthy controls using quantitative real-time PCR (qPCR). Cell counting kit-8 (CCK-8) and Annexin V-FITC/PI analyses were used to measure the effects of miR-362-5p on proliferation and apoptosis, and Transwell assays were used to evaluate migration and invasion. A xenograft model was used to examine in vivo tumourigenicity. The potential target of miR-362-5p was confirmed by a luciferase reporter assay, qPCR and western blotting. Involvement of the JNK_1/2 and P38 pathways was investigated by western blotting.

Results

miR-362-5p was up-regulated in CML cell lines and fresh blood samples from CML patients, and was associated with Growth arrest and DNA damage-inducible (GADD)45α down-regulation. Inhibition of miR-362-5p simultaneously repressed tumour growth and up-regulated GADD45α expression in a xenograft model. Consistently, the knockdown of GADD45α expression partially neutralized the effects of miR-362-5p inhibition. Furthermore study suggested that GADD45α mediated downstream the effects of miR-362-5p, which might indirectly regulates the activation of the JNK_1/2 and P38 signalling pathways.

Conclusion

miR-362-5p acts as an oncomiR that down-regulates GADD45α, which consequently activates the JNK_1/2 and P38 signalling. This finding provides novel insights into CML leukaemogenesis and may help identify new diagnostic and therapeutic targets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0465-3) contains supplementary material, which is available to authorized users.

Combination of serum miRNAs with Cyfra21-1 for the diagnosis of non-small cell lung cancer

In this study, we screened 381 miRNAs by RT-qPCR in serum samples of 44 NSCLC patients and 22 healthy individuals to identify altered miRNAs, and validated the results in a training and test cohorts with 300 serum samples (178 NSCLC and 122 healthy individuals). Three miRNAs (miR-194, miR-652 and miR-660) were selected from 380 miRNAs by two normalization methods in the discovery cohort, and miR-652 and miR-660 were confirmed to be significantly upregulated in ADC and SCC patients compared with healthy controls both in the training and test cohorts (p < 0.01). The combination of miR-652 and miR-660 exhibited significantly higher AUC than miR-660, CEA and CA125 for ADC and SCC diagnosis in both the training and test cohorts (p < 0.05). Furthermore, miR-652 + miR-660 + Cyfra21-1 significantly improved the diagnostic ability to determine ADC patients from healthy controls. For SCC diagnosis, miR-652 + miR-660 + Cyfra21-1 exhibited comparable ability to Cyfra21-1. The results indicate that the combination of miR-652 + miR-660 and Cyfra21-1 has the potential to help in the diagnosis of NSCLC, especially for ADC.

Predictive and prognostic biomarkers for neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Locally advanced rectal cancer is regularly treated with trimodality therapy consisting of neoadjuvant chemoradiation, surgery and adjuvant chemotherapy. There is a need for biomarkers to assess treatment response, and aid in stratification of patient risk to adapt and personalise components of the therapy. Currently, pathological stage and tumour regression grade are used to assess response. Experimental markers include proteins involved in cell proliferation, apoptosis, angiogenesis, the epithelial to mesenchymal transition and microsatellite instability. As yet, no single marker is sufficiently robust to have clinical utility. Microarrays that screen a tumour for multiple promising candidate markers, gene expression and microRNA profiling will likely have higher yield and it is expected that a combination or panel of markers would prove most useful. Moving forward, utilising serial samples of circulating tumour cells or circulating nucleic acids can potentially allow us to demonstrate tumour heterogeneity, document mutational changes and subsequently measure treatment response.

WITHDRAWN: Combination of serum miRNAs with Cyfra21-1 for the diagnosis of non-small cell lung cancer

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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.

Global MicroRNA Analysis in Primary Hepatocyte Cultures

MicroRNAs are small non-coding molecules that regulate gene expression and in return affect diverse biological functions, including those involved in toxicity and development of disease. Recent evidence suggests that microRNAs play an important role in liver pathologies, like viral hepatitis, alcoholic liver, hepatocellular carcinoma, or drug-induced liver injury. Furthermore, numerous studies demonstrated the high potential of microRNAs as promising non-invasive biomarkers of liver disease or as relevant targets for therapeutic treatment. This chapter describes a method for global microRNA analysis of primary hepatocytes by high-throughput sequencing. The method comprises the isolation of high-quality total RNA, analysis of microRNA sequencing data, and the validation of the findings by reverse transcriptase quantitative polymerase chain reaction analysis.

Introduction to microRNAs: Biogenesis, Action, Relevance of Tissue microRNAs in Disease Pathogenesis, Diagnosis and Therapy-The Concept of Circulating microRNAs

MicroRNAs as the endogenous mediators of RNA interference have principal roles in gene expression regulation. Since their discovery in the early 1990s, their number has steadily grown to approximately 2500 known microRNAs at present in humans. MicroRNAs encoded by distinct genes regulate the expression of about 30-60 % of human protein coding genes by targeting their messenger RNAs (mRNAs) and induce mostly posttranscriptional inhibition, or in some cases enhancement. MicroRNAs, as fine regulators of the gene expression, have important roles in development, the physiological functioning of the organism, e.g. organogenesis, immune functioning, vascular system, etc. The deregulation of microRNA expression has been observed in many disorders, such as in carcinogenesis. Given their tissue specificity and stability, and specific disease-related alterations, tissue microRNAs can be exploited as excellent biomarkers in the diagnosis. Moreover, microRNAs might also be envisaged as novel therapeutic targets. Beside tissue microRNAs, novel data show that microRNAs are also present in body fluids that could further extend their diagnostic utility as minimally invasive biomarkers of various diseases, but also raises intriguing questions regarding their biological relevance. In this introductory chapter, we summarise the most relevant features of microRNAs including their biogenesis, action, the biological, pathological, diagnostic and potential therapeutical relevance of tissue microRNAs.

microRNAs as a new mechanism regulating adipose tissue inflammation in obesity and as a novel therapeutic strategy in the metabolic syndrome

Obesity is associated closely with the metabolic syndrome (MS). It is well known that obesity-induced chronic inflammation plays a fundamental role in the pathogenesis of MS. White adipose tissue (AT) is the primary site for the initiation and exacerbation of obesity-associated inflammation. Exploring the mechanisms of white AT inflammation and resetting the immunological balance in white AT could be crucial for the management of MS. Several prominent molecular mechanisms have been proposed to mediate inflammation in white AT, including hypoxia, endoplasmic reticulum stress, lipotoxicity, and metabolic endotoxemia. Recently, a growing body of evidence supports the role of miRNAs as a new important inflammatory mediator by regulating both the adaptive and innate immunity. This review will focus on the implication of miRNAs in white AT inflammation in obesity, and will also highlight the potential of miRNAs as targets for therapeutic intervention in MS as well as the challenges lying in miRNA-targeting therapeutics.

Regulation of the apolipoprotein gene cluster by a long noncoding RNA

Apolipoprotein A1 (APOA1) is the major protein component of high-density lipoprotein (HDL) in plasma. We have identified an endogenously expressed long noncoding natural antisense transcript, APOA1-AS, which acts as a negative transcriptional regulator of APOA1 both in vitro and in vivo. Inhibition of APOA1-AS in cultured cells resulted in the increased expression of APOA1 and two neighboring genes in the APO cluster. Chromatin immunoprecipitation (ChIP) analyses of a ∼50 kb chromatin region flanking the APOA1 gene demonstrated that APOA1-AS can modulate distinct histone methylation patterns that mark active and/or inactive gene expression through the recruitment of histone-modifying enzymes. Targeting APOA1-AS with short antisense oligonucleotides also enhanced APOA1 expression in both human and monkey liver cells and induced an increase in hepatic RNA and protein expression in African green monkeys. Furthermore, the results presented here highlight the significant local modulatory effects of long noncoding antisense RNAs and demonstrate the therapeutic potential of manipulating the expression of these transcripts both in vitro and in vivo.

Identification and validation of miRNAs as endogenous controls for RQ-PCR in blood specimens for breast cancer studies

Introduction

A prerequisite to accurate interpretation of RQ-PCR data is robust data normalization. A commonly used method is to compare the cycle threshold (C_T) of target miRNAs with those of a stably expressed endogenous (EC) miRNA(s) from the same sample. Despite the large number of studies reporting miRNA expression patterns, comparatively few appropriate ECs have been reported thus far. The purpose of this study was to identify stably expressed miRNAs with which to normalize RQ-PCR data derived from human blood specimens.

Methods

MiRNA profiling of approximately 380 miRNAs was performed on RNA derived from blood specimens from 10 women with breast cancer and 10 matched controls. Analysis of mean expression values across the dataset (GME) identified stably expressed candidates. Additional candidates were selected from the literature and analyzed by the geNorm algorithm. Further validation of three candidate ECs by RQ-PCR was performed in a larger cohort (n = 40 cancer, n = 20 control) was performed, including analysis by geNorm and NormFinder algorithms.

Results

Microarray screening identified 10 candidate ECs with expression patterns closest to the global mean. Geometric averaging of candidate ECs from the literature using geNorm identified miR-425 as the most stably expressed miRNA. MiR-425 and miR-16 were the best combination, achieving the lowest V-value of 0.185. Further validation by RQ-PCR confirmed that miR-16 and miR-425 were the most stably expressed ECs overall. Their combined use to normalize expression data enabled the detection of altered target miRNA expression that reliably differentiated between cancers and controls in human blood specimens.

Conclusion

This study identified that the combined use of 2 miRNAs, (miR-16 and miR-425) to normalize RQ-PCR data generated more reliable results than using either miRNA alone, or use of U6. Further investigation into suitable ECs for use in miRNA RQ-PCR studies is warranted.

Epigenetic regulation of mmp-9 gene expression

Matrix metalloproteinase 9 (MMP-9) is one of the most studied enzymes in cancer. MMP-9 can cleave proteins of the extracellular matrix and a large number of receptors and growth factors. Accordingly, its expression must be tightly regulated to avoid excessive enzymatic activity, which is associated with disease progression. Although we know that epigenetic mechanisms play a central role in controlling mmp-9 gene expression, predicting how epigenetic drugs could be used to suppress mmp-9 gene expression is not trivial because epigenetic drugs also regulate the expression of key proteins that can tip the balance towards activation or suppression of MMP-9. Here, we review how our understanding of the biology and expression of MMP-9 could be exploited to augment clinical benefits, most notably in terms of the prevention and management of degenerative diseases and cancer.

Structure and dynamics of molecular networks: a novel paradigm of drug discovery: a comprehensive review

Despite considerable progress in genome- and proteome-based high-throughput screening methods and in rational drug design, the increase in approved drugs in the past decade did not match the increase of drug development costs. Network description and analysis not only give a systems-level understanding of drug action and disease complexity, but can also help to improve the efficiency of drug design. We give a comprehensive assessment of the analytical tools of network topology and dynamics. The state-of-the-art use of chemical similarity, protein structure, protein-protein interaction, signaling, genetic interaction and metabolic networks in the discovery of drug targets is summarized. We propose that network targeting follows two basic strategies. The "central hit strategy" selectively targets central nodes/edges of the flexible networks of infectious agents or cancer cells to kill them. The "network influence strategy" works against other diseases, where an efficient reconfiguration of rigid networks needs to be achieved by targeting the neighbors of central nodes/edges. It is shown how network techniques can help in the identification of single-target, edgetic, multi-target and allo-network drug target candidates. We review the recent boom in network methods helping hit identification, lead selection optimizing drug efficacy, as well as minimizing side-effects and drug toxicity. Successful network-based drug development strategies are shown through the examples of infections, cancer, metabolic diseases, neurodegenerative diseases and aging. Summarizing >1200 references we suggest an optimized protocol of network-aided drug development, and provide a list of systems-level hallmarks of drug quality. Finally, we highlight network-related drug development trends helping to achieve these hallmarks by a cohesive, global approach.

Upregulation of miR-150* and miR-630 induces apoptosis in pancreatic cancer cells by targeting IGF-1R

MicroRNAs have been implicated in many critical cellular processes including apoptosis. We have previously found that apoptosis in pancreatic cancer cells was induced by adamantyl retinoid-related (ARR) molecule 3-Cl-AHPC. Here we report that 3-Cl-AHPC-dependent apoptosis involves regulating a number of microRNAs including miR-150* and miR-630. 3-Cl-AHPC stimulated miR-150* expression and caused decreased expression of c-Myb and IGF-1R in the pancreatic cancer cells. 3-Cl-AHPC-mediated reduction of c-Myb resulted in diminished binding of c-Myb with IGF-1R and Bcl-2 promoters, thereby causing repression of their transcription and protein expression. Over-expression of miR-150* also resulted in diminished levels of c-Myb and Bcl-2 proteins. Furthermore, the addition of the miRNA inhibitor 2′-O-methylated miR-150 blocked 3-Cl-AHPC-mediated increase in miR-150* levels and abrogated loss of c-Myb protein. Knockdown of c-Myb in PANC-1 cells resulted in enhanced apoptosis both in the presence or absence of 3-Cl-AHPC confirming the anti-apoptotic property of c-Myb. Overexpression of miR-630 also induced apoptosis in the pancreatic cancer cells and inhibited target protein IGF-1R mRNA and protein expression. Together these results implicate key roles for miR-150* and miR-630 and their targeting of IGF-1R to promote apoptosis in pancreatic cancer cells.

Enoxacin inhibits growth of prostate cancer cells and effectively restores microRNA processing

Prostate cancer (PCa) is one of the most incident malignancies worldwide. Although efficient therapy is available for early-stage PCa, treatment of advanced disease is mainly ineffective and remains a clinical challenge. microRNA (miRNA) dysregulation is associated with PCa development and progression. In fact, several studies have reported a widespread downregulation of miRNAs in PCa, which highlights the importance of studying compounds capable of restoring the global miRNA expression. The main aim of this study was to define the usefulness of enoxacin as an anti-tumoral agent in PCa, due to its ability to induce miRNA biogenesis in a TRBP-mediated manner. Using a panel of five PCa cell lines, we observed that all of them were wild type for the TARBP2 gene and expressed TRBP protein. Furthermore, primary prostate carcinomas displayed normal levels of TRBP protein. Remarkably, enoxacin was able to decrease cell viability, induce apoptosis, cause cell cycle arrest, and inhibit the invasiveness of cell lines. Enoxacin was also effective in restoring the global expression of miRNAs. This study is the first to show that PCa cells are highly responsive to the anti-tumoral effects of enoxacin. Therefore, enoxacin constitutes a promising therapeutic agent for PCa.

Potent microRNA suppression by RNA Pol II-transcribed 'Tough Decoy' inhibitors

MicroRNAs (miRNAs) are key regulators of gene expression and modulators of diverse biological pathways. Analyses of miRNA function as well as therapeutic managing of miRNAs rely on cellular administration of miRNA inhibitors which may be achieved by the use of viral vehicles. This study explores the miRNA-suppressive capacity of inhibitors expressed intracellularly from lentivirus-derived gene vectors. Superior activity of two decoy-type inhibitors, a "Bulged Sponge" with eight miRNA recognition sites and a hairpin-shaped "Tough Decoy" containing two miRNA recognition sites, is demonstrated in a side-by-side comparison of seven types of miRNA inhibitors transcribed as short RNAs from an RNA Pol III promoter. We find that lentiviral vectors expressing Tough Decoy inhibitors are less vulnerable than Bulged Sponge-encoding vectors to targeting by the cognate miRNA and less prone, therefore, to reductions in transfer efficiency. Importantly, it is demonstrated that Tough Decoy inhibitors retain their miRNA suppression capacity in the context of longer RNA transcripts expressed from an RNA Pol II promoter. Such RNA Pol II-transcribed Tough Decoy inhibitors are new tools in managing of miRNAs and may have potential for temporal and spatial regulation of miRNA activity as well as for therapeutic targeting of miRNAs that are aberrantly expressed in human disease.

Two panels of plasma microRNAs as non-invasive biomarkers for prediction of recurrence in resectable NSCLC

The diagnosis of non-small cell lung carcinoma (NSCLC) at an early stage, as well as better prediction of outcome remains clinically challenging due to the lack of specific and robust non-invasive markers. The discovery of microRNAs (miRNAs), particularly those found in the bloodstream, has opened up new perspectives for tumor diagnosis and prognosis. The aim of our study was to determine whether expression profiles of specific miRNAs in plasma could accurately discriminate between NSCLC patients and controls, and whether they are able to predict the prognosis of resectable NSCLC patients. We therefore evaluated a series of seventeen NSCLC-related miRNAs by quantitative real-time (qRT)-PCR in plasma from 52 patients with I-IIIA stages NSCLC, 10 patients with chronic obstructive pulmonary disease (COPD) and 20-age, sex and smoking status-matched healthy individuals. We identified an eleven-plasma miRNA panel that could distinguish NSCLC patients from healthy subjects (AUC = 0.879). A six-plasma miRNA panel was able to discriminate between NSCLC patients and COPD patients (AUC = 0.944). Furthermore, we identified a three-miRNA plasma signature (high miR-155-5p, high miR-223-3p, and low miR-126-3p) that significantly associated with a higher risk for progression in adenocarcinoma patients. In addition, a three-miRNA plasma panel (high miR-20a-5p, low miR-152-3p, and low miR-199a-5p) significantly predicted survival of squamous cell carcinoma patients. In conclusion, we identified two plasma miRNA expression profiles that may be useful for predicting the outcome of patients with resectable NSCLC.

Suppression of microRNAs by dual-targeting and clustered Tough Decoy inhibitors

MicroRNAs (miRNAs) are ubiquitous regulators of gene expression that contribute to almost any cellular process. Methods for managing of miRNA activity are attracting increasing attention in relation to diverse experimental and therapeutic applications. DNA-encoded miRNA inhibitors expressed from plasmid or virus-based vectors provide persistent miRNA suppression and options of tissue-directed micromanaging. In this report, we explore the potential of exploiting short, hairpin-shaped RNAs for simultaneous suppression of two or more miRNAs. Based on the "Tough Decoy" (TuD) design, we create dual-targeting hairpins carrying two miRNA recognition sites and demonstrate potent co-suppression of different pairs of unrelated miRNAs by a single DNA-encoded inhibitor RNA. In addition, enhanced miRNA suppression is achieved by expression of RNA polymerase II-transcribed inhibitors carrying clustered TuD hairpins with up to a total of eight miRNA recognition sites. Notably, by expressing clustered TuD inhibitors harboring a single recognition site for each of a total of six miRNAs, we document robust parallel suppression of multiple miRNAs by inhibitor RNA molecules encoded by a single expression cassette. These findings unveil a new potential of TuD-based miRNA inhibitors and pave the way for standardizing synchronized suppression of families or clusters of miRNAs.

MicroRNAs in the hypothalamus

MicroRNAs (miRNAs) are short (∼22 nucleotides) non-coding ribonucleic acid (RNA) molecules that negatively regulate the expression of protein-coding genes. Posttranscriptional silencing of target genes by miRNA is initiated by binding to the 3'-untranslated regions of target mRNAs, resulting in specific cleavage and subsequent degradation of the mRNA or by translational repression resulting in specific inhibition of protein synthesis. An increasing amount of evidence shows that miRNAs control a large number of biological processes and there exists a direct link between miRNAs and disease. miRNA molecules are abundantly expressed in tissue-specific and regional patterns and have been suggested as potential biomarkers, disease modulators and drug targets. The central nervous system is a prominent site of miRNA expression. Within the brain, several miRNAs are expressed and/or enriched in the region of the hypothalamus and miRNAs have recently been shown to be important regulators of hypothalamic control functions. The aim of this review is to summarize some of the current knowledge regarding the expression and role of miRNAs in the hypothalamus.

Developing microRNA therapeutics: approaching the unique complexities

MicroRNAs are endogenous small non-coding RNAs that regulate gene expression by interfering with translation or stability of target transcripts. The importance of microRNAs for maintaining biological functions is illustrated by the fact that microRNAs are exploited in nature to regulate phenotypes, and by the diverse disease phenotypes that result when microRNAs are mutated or improperly expressed. Disease-associated microRNAs might therefore represent a new class of therapeutic targets. With the recent demonstration that inhibition of miR-122 reduces viral load in hepatitis C patients, microRNA modulators are no longer merely theoretical, but rather, have become strong candidate therapeutics. The complexity of microRNA biology offers a novel mechanism of action for therapeutic intervention but also poses unique challenges for the development of therapeutic modulators as drugs.

Locked nucleic acid-based in situ hybridisation reveals miR-7a as a hypothalamus-enriched microRNA with a distinct expression pattern

MicroRNAs (miRNAs) are short (∼22 nucleotides) noncoding RNA molecules that post-transcriptionally repress the expression of protein-coding genes by binding to 3'-untranslated regions of the target mRNAs. To identify miRNAs selectively expressed within the hypothalamus, a part of the brain that controls vital bodily functions, we employed locked nucleic acid (LNA)-fluorescent in situ hybridisation (FISH). The expression pattern of the mature miRNAs miR-7a, miR-7b, miR-137 and miR-153 in mouse brain tissue sections was investigated. Although all studied miRNAs were present in the hypothalamus, miR-7a, was the only miRNA found to be enriched in the hypothalamus, with low or no expression in other parts of the central nervous system (CNS). Within the hypothalamus, strong miR-7a expression was distinct and restricted to some hypothalamic nuclei and adjacent areas. miR-7a expression was particularly prominent in the subfornical organ, as well as the suprachiasmatic, paraventricular, periventricular, supraoptic, dorsomedial and arcuate nuclei. Identical expression patterns for miR-7a were seen in mouse and rat hypothalamus. By combining LNA-FISH with immunohistochemistry, it was shown that miR-7a was preferentially present in small orexigenic neuropeptide Y/agouti-related protein-containing-neurones located in the ventromedial aspect of the arcuate nucleus but not in large pro-opiomelanocortin/cocaine- and amphetamine-regulated transcript-containing anorexigenic neurones of the ventrolateral part of the arcuate nucleus. The limited and distinct expression of miR-7a in the CNS suggests that miR-7a has a role in post-transcriptional regulation in hypothalamic neurones. Particularly strong expression of miR-7a in neurones located in the ventromedial division of the arcuate nucleus, a subregion with a weak blood-brain barrier, raises the possibility that miR-7a is influenced by circulating hormones and is a regulator of the genes involved in body weight control.

[Relevance of long non-coding RNAs in tumour biology]

The discovery of the biological relevance of non-coding RNA molecules represents one of the most significant advances in contemporary molecular biology. It has turned out that a major fraction of the non-coding part of the genome is transcribed. Beside small RNAs (including microRNAs) more and more data are disclosed concerning long non-coding RNAs of 200 nucleotides to 100 kb length that are implicated in the regulation of several basic molecular processes (cell proliferation, chromatin functioning, microRNA-mediated effects, etc.). Some of these long non-coding RNAs have been associated with human tumours, including H19, HOTAIR, MALAT1, etc., the different expression of which has been noted in various neoplasms relative to healthy tissues. Long non-coding RNAs may represent novel markers of molecular diagnostics and they might even turn out to be targets of therapeutic intervention.

Noncanonical mechanisms to regulate nuclear receptor signaling

Nuclear receptor (NR)-targeted therapies comprise a large class of clinically employed drugs. A number of drugs currently being used against this protein class were designed as structural analogs of the endogenous ligand of these receptors. In recent years, there has been significant interest in developing newer strategies to target NRs, especially those that rely on mechanistic pathways of NR function. Prominent among these are noncanonical means of targeting NRs, which include selective NR modulation, NR coactivator interaction inhibition, inhibition of NR DNA binding, modulation of NR cellular localization, modulation of NR ligand biosynthesis and downregulation of NR levels in target tissues. This article reviews each of these promising emerging strategies for NR drug development and highlights some of most significant successes achieved in using them.

Synthesis of 6-amino-2-vinylpurine derivatives for cross-linking and evaluation of the reactivity

Oligodeoxynucleotides (ODNs) have been widely used for inhibiting the gene expression in antisense or antigene methods, and the interstrand cross-linking (ICL) forming ODNs have been expected to ensure the inhibition by these methods. Previously, we reported a highly efficient and selective ICL reaction toward cytosine using the 2-amino-6-vinylpurine derivative under acidic conditions. In this Letter, we report the synthesis of ODN containing 6-amino-2-vinylpurine derivatives and evaluation of the cross-linking reactivity.

The microRNA (miR)-199a/214 cluster mediates opposing effects of progesterone and estrogen on uterine contractility during pregnancy and labor

Progesterone (P(4)) and estradiol-17β (E(2)) play critical and opposing roles in regulating myometrial quiescence and contractility during pregnancy and labor. Although these contrasting hormonal effects are likely mediated via differential regulation of inflammatory and contractile genes, the underlying mechanisms remain incompletely understood. Recently we discovered that targets of the microRNA (miR)-200 family, transcription factors zinc finger E-box binding homeobox (ZEB)-1 and ZEB2, serve as P(4)/progesterone receptor-mediated regulators of uterine quiescence during pregnancy. In the present study, we found that levels of the clustered miRNAs, miR-199a-3p and miR-214, were significantly decreased in laboring myometrium of pregnant mice and humans and in an inflammatory mouse model of preterm labor, whereas the miR-199a-3p/miR-214 target, cyclooxygenase-2, a critical enzyme in synthesis of proinflammatory prostaglandins, was coordinately increased. Overexpression of miR-199a-3p and miR-214 in cultured human myometrial cells inhibited cyclooxygenase-2 protein and blocked TNF-α-induced myometrial cell contractility, suggesting their physiological relevance. Notably, E(2) treatment of ovariectomized mice suppressed, whereas P(4) enhanced uterine miR-199a-3p/214 expression. Intriguingly, these opposing hormonal effects were mediated by ZEB1, which is induced by P(4), inhibited by E(2) and activates miR199a/214 transcription. Together, these findings identify miR-199a-3p/miR-214 as important regulators of myometrial contractility and provide new insight into strategies to prevent preterm birth.