MicroRNAs as New Players in the Genomic Galaxy and Disease Puzzles

MicroRNAs (miRNAs) are a large family of short, single‐stranded, highly conserved noncoding RNAs involved in gene regulation that can regulate gene expression through sequence‐specific base pairing with target messenger RNAs (mRNAs). miRNAs have been implicated in the development of a wide variety of cancers as well as heart disease and other diseases. This review describes the role of miRNAs in human disease, methodology for evaluating miRNA gene expression, and the potential role of miRNAs as therapeutic agents and targets for the treatment of disease.     

Anti-miRNA oligonucleotides (AMOs): ammunition to target miRNAs implicated in human disease?

MicroRNAs (miRNAs) are endogenous 19-25 nucleotide RNAs that have recently emerged as a novel class of important gene-regulatory molecules involved in many critical developmental and cellular functions. miRNAs have been implicated in the pathogenesis of several human diseases, such as neurodegenerative disorders, cancer, and more recently in viral and metabolic diseases. Unraveling the roles of miRNAs in cellular processes linked to human diseases will lead to novel opportunities for the regulation of protein function and will help to evaluate their potential for therapeutic intervention. Approaches to interfere with miRNA function in vitro and in vivo based on synthetic anti-miRNA oligonucleotides (AMOs) are discussed in this review.     

A miRNA Signature of Prion Induced Neurodegeneration

MicroRNAs (miRNAs) are small, non-coding RNA molecules which are emerging as key regulators of numerous cellular processes. Compelling evidence links miRNAs to the control of neuronal development and differentiation, however, little is known about their role in neurodegeneration. We used microarrays and RT-PCR to profile miRNA expression changes in the brains of mice infected with mouse-adapted scrapie. We determined 15 miRNAs were de-regulated during the disease processes; miR-342-3p, miR-320, let-7b, miR-328, miR-128, miR-139-5p and miR-146a were over 2.5 fold up-regulated and miR-338-3p and miR-337-3p over 2.5 fold down-regulated. Only one of these miRNAs, miR-128, has previously been shown to be de-regulated in neurodegenerative disease. De-regulation of a unique subset of miRNAs suggests a conserved, disease-specific pattern of differentially expressed miRNAs is associated with prion–induced neurodegeneration. Computational analysis predicted numerous potential gene targets of these miRNAs, including 119 genes previously determined to be also de-regulated in mouse scrapie. We used a co-ordinated approach to integrate miRNA and mRNA profiling, bioinformatic predictions and biochemical validation to determine miRNA regulated processes and genes potentially involved in disease progression. In particular, a correlation between miRNA expression and putative gene targets involved in intracellular protein-degradation pathways and signaling pathways related to cell death, synapse function and neurogenesis was identified.     

MicroRNAs: role in cardiovascular biology and disease

miRNAs (microRNAs) comprise a novel class of endogenous, small, non-coding RNAs that negatively regulate gene expression via degradation or translational inhibition of their target mRNAs. Recent studies have demonstrated that miRNAs are highly expressed in the cardiovascular system. Although we are currently in the initial stages of understanding how this novel class of gene regulators is involved in cardiovascular biological functions, a growing body of exciting evidence suggests that miRNAs are important regulators of cardiovascular cell differentiation, growth, proliferation and apoptosis. Moreover, miRNAs are key modulators of both cardiovascular development and angiogenesis. Consequently, dysregulation of miRNA function may lead to cardiovascular diseases. Indeed, several recent reports have demonstrated that miRNAs are aberrantly expressed in diseased hearts and vessels. Modulating these aberrantly expressed miRNAs has significant effects on cardiac hypertrophy, vascular neointimal lesion formation and cardiac arrhythmias. Identifying the roles of miRNAs and their target genes and signalling pathways in cardiovascular disease will be critical for future research. miRNAs may represent a new layer of regulators for cardiovascular biology and a novel class of therapeutic targets for cardiovascular diseases.     

Hepcidin and its therapeutic potential in neurodegenerative disorders

Abnormally high brain iron, resulting from the disrupted expression or function of proteins involved in iron metabolism in the brain, is an initial cause of neuronal death in neuroferritinopathy and aceruloplasminemia, and also plays a causative role in at least some of the other neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, and Friedreich's ataxia. As such, iron is believed to be a novel target for pharmacological intervention in these disorders. Reducing iron toward normal levels or hampering the increases in iron associated with age in the brain is a promising therapeutic strategy for all iron-related neurodegenerative disorders. Hepcidin is a crucial regulator of iron homeostasis in the brain. Recent studies have suggested that upregulating brain hepcidin levels can significantly reduce brain iron content through the regulation of iron transport protein expression in the blood-brain barrier and in neurons and astrocytes. In this review, we focus on the discussion of the therapeutic potential of hepcidin in iron-associated neurodegenerative diseases and also provide a systematic overview of recent research progress on how misregulated brain iron metabolism is involved in the development of multiple neurodegenerative disorders.     

Thymosin β4 as a restorative/regenerative therapy for neurological injury and neurodegenerative diseases

Thymosin β4 (Tβ4) promotes CNS and peripheral nervous system (PNS) plasticity and neurovascular remodeling leading to neurological recovery in a range of neurological diseases. Treatment of neural injury and neurodegenerative disease 24 h or more post-injury and disease onset with Tβ4 enhances angiogenesis, neurogenesis, neurite and axonal outgrowth, and oligodendrogenesis, and thereby, significantly improves functional and behavioral outcomes. We propose that oligodendrogenesis is a common link by which Tβ4 promotes recovery after neural injury and neurodegenerative disease. The ability to target many diverse restorative processes via multiple molecular pathways that drive oligodendrogenesis and neurovascular remodeling may be mediated by the ability of Tβ4 to alter cellular expression of microRNAs (miRNAs). However, further investigations on the essential role of miRNAs in regulating protein expression and the remarkable exosomal intercellular communication network via exosomes will likely provide insight into mechanisms of action and means to amplify the therapeutic effects of Tβ4.     

MicroRNA as a novel drug target for cancer therapy

INTRODUCTION: MicroRNAs (miRNAs), a class of small, regulatory and non-coding RNA molecules, display aberrant expression patterns and functional abnormalities in all kinds of human diseases including cancers. As important emerging modulators in cellular pathways, miRNAs play a key role in tumorigenesis. Correcting these miRNA deficiencies by either up-regulating or down-regulating miRNA function may provide a therapeutic benefit. AREAS COVERED: We herein provide a brief review of miRNA in the following aspects: their possible role of miRNA as oncogenes or tumor suppressors in the pathogenesis of cancer, the abnormally expressed miRNAs in various types of human common cancers, novel drug targets and therapeutic tools for diagnosis, prognosis and treatments of human cancers was also discussed. Finally, we comment on the difficulties and challenges of miRNAs in clinical practice, and the bright perspective for future application. EXPERT OPINION: Targeting of these ectopically miRNAs could provide an important diagnostic or therapeutic strategy for human cancer in the future.     

Differential Micro RNA Expression in PBMC from Multiple Sclerosis Patients

Differences in gene expression patterns have been documented not only in Multiple Sclerosis patients versus healthy controls but also in the relapse of the disease. Recently a new gene expression modulator has been identified: the microRNA or miRNA. The aim of this work is to analyze the possible role of miRNAs in multiple sclerosis, focusing on the relapse stage. We have analyzed the expression patterns of 364 miRNAs in PBMC obtained from multiple sclerosis patients in relapse status, in remission status and healthy controls. The expression patterns of the miRNAs with significantly different expression were validated in an independent set of samples. In order to determine the effect of the miRNAs, the expression of some predicted target genes of these were studied by qPCR. Gene interaction networks were constructed in order to obtain a co-expression and multivariate view of the experimental data. The data analysis and later validation reveal that two miRNAs (hsa-miR-18b and hsa-miR-599) may be relevant at the time of relapse and that another miRNA (hsa-miR-96) may be involved in remission. The genes targeted by hsa-miR-96 are involved in immunological pathways as Interleukin signaling and in other pathways as wnt signaling. This work highlights the importance of miRNA expression in the molecular mechanisms implicated in the disease. Moreover, the proposed involvement of these small molecules in multiple sclerosis opens up a new therapeutic approach to explore and highlight some candidate biomarker targets in MS.     

Advancements in microRNA based cancer therapeutics

Abstract: Research efforts on non coding RNAs have grown exponentially in the past decade. We are now beginning to witness the achievements that have been made in better understanding the roles of miRNAs in human diseases such as cancer and cardiovascular diseases. miRNAs show great promise as biomarkers for cancer diagnosis and prognosis. In addition, miRNAs, due to their critical function as either oncogenes or tumor suppressor genes and their broad impact on target genes and pathways, have great potential as therapeutic agents for novel cancer drug development. Several miRNA molecules and mimics are getting close to clinical trials. In this review, we summarize and highlight some of the important findings relating to miRNA and anticancer therapeutic development.     

microRNA在自身免疫性疾病中的研究进展

microRNA（简称miRNA）是一类新发现、短序列的、非编码的小分子RNA,参与基因组转录后水平的调节。当前认为miRNA可以调控30%人类编码蛋白质的基因,且一种miRNA可以和多个靶mRNA结合;miRNA在免疫细胞增殖、分化、成熟、免疫稳态的维持等方面有重要调控作用。近来研究证实异常表达的miRNA与某些疾病如肿瘤、炎症性疾病及自身免疫性疾病等发病有关。本文就当前对于miRNA生物学特性,及其与自身免疫性疾病的关系进行综述。     

Multifunctional Aptamer-miRNA Conjugates for Targeted Cancer Therapy

While microRNAs (miRNAs) clearly regulate multiple pathways integral to disease development and progression, the lack of safe and reliable means for specific delivery of miRNAs to target tissues represents a major obstacle to their broad therapeutic application. Our objective was to explore the use of nucleic acid aptamers as carriers for cell-targeted delivery of a miRNA with tumor suppressor function, let-7g. Using an aptamer that binds to and antagonizes the oncogenic receptor tyrosine kinase Axl (GL21.T), here we describe the development of aptamer-miRNA conjugates as multifunctional molecules that inhibit the growth of Axl-expressing tumors. We conjugated the let-7g miRNA to GL21.T and demonstrate selective delivery to target cells, processing by the RNA interference machinery, and silencing of let-7g target genes. Importantly, the multifunctional conjugate reduced tumor growth in a xenograft model of lung adenocarcinoma. Therefore, our data establish aptamer-miRNA conjugates as a novel tool for targeted delivery of miRNAs with therapeutic potential.     

缺氧预处理诱导的乳鼠心肌细胞miRNA表达谱的变化

目的 分析大鼠乳鼠心肌细胞经历缺氧预处理后miRNA的表达谱变化,探索其缺氧预处理机制和治疗靶点。方法 大鼠乳鼠心肌细胞原代培养,经过缺氧预处理和缺氧复氧损伤后检验心肌细胞存活率和乳酸脱氢酶浓度,miRNA芯片技术检测正常心肌和缺氧预处理心肌细胞miRNA表达谱差异,实时定量PCR验证结果的可信性,分析明显差异表达的miRNA的生物学功能。结果 心肌细胞存活率和乳酸脱氢酶浓度结果证实缺氧预处理模型制备成功。miRNA芯片技术结果表明,与正常对照组心肌细胞相比,缺氧预处理心肌细胞中有6个miRNA表达上调,有5个表达下调,其中一部分miRNA的生物学功能与心血管功能相关。结论 缺氧预处理可导致大鼠乳鼠心肌细胞microRNA表达谱发生变化,其可能是缺氧复氧损伤潜在的治疗靶点。     

MicroRNAs 的失调在高转移肝细胞癌中的作用

目的：筛选在高转移肝细胞癌中差异表达的miRNAs图谱。方法利用Agilent miRNA array芯片技术平台分析比较了4对高转移肝细胞患者的癌组织样本与其相对应的正常组织之间的差异miRNAs。通过生物信息学方法分析了这些候选差异 miRNAs。结果与正常组织相比,我们在高转移肝细胞癌中发现了22个失调的miRNAs,其中包括13个上调的miRNAs（miR-200a、miR-425、miR-221和miR-20b等）和9个下调的miRNAs（miR-762、miR-638和miR-1305等）。其中,一些miRNAs已经被报道与肿瘤的发生和转移相关。靶基因预测分析也表明,这些基因在肿瘤的发生和转移过程中扮演着重要的作用。结论我们在高转移肝细胞癌中发现了一些表达失调的 miRNAs,生物信息学分析也发现这些 miRNAs 在肿瘤的发生和转移中发挥着重要的作用,可以作为肝细胞癌在临床治疗上的一个新的肿瘤标志物。     

MicroRNA as a novel drug target for cancer therapy

Introduction: MicroRNAs (miRNAs), a class of small, regulatory and non-coding RNA molecules, display aberrant expression patterns and functional abnormalities in all kinds of human diseases including cancers. As important emerging modulators in cellular pathways, miRNAs play a key role in tumorigenesis. Correcting these miRNA deficiencies by either up-regulating or down-regulating miRNA function may provide a therapeutic benefit.

Areas covered: We herein provide a brief review of miRNA in the following aspects: their possible role of miRNA as oncogenes or tumor suppressors in the pathogenesis of cancer, the abnormally expressed miRNAs in various types of human common cancers, novel drug targets and therapeutic tools for diagnosis, prognosis and treatments of human cancers was also discussed. Finally, we comment on the difficulties and challenges of miRNAs in clinical practice, and the bright perspective for future application.

Expert opinion: Targeting of these ectopically miRNAs could provide an important diagnostic or therapeutic strategy for human cancer in the future.