let-7a及其靶基因在肝细胞癌中作用机制的研究进展

肝细胞癌（hepatocellular carcinoma,HCC）是全球范围内最具侵袭性的恶性肿瘤之一,具有较高的复发率和死亡率。大多数恶性肿瘤中微小RNA(microRNA,miRNA)呈异常表达,可影响肿瘤的发生、发展、转移和复发。miRNA可通过靶向不同靶基因,参与不同信号通路,从而在疾病的发生发展、生物发育、器官形成、病毒防御、表观调控及代谢等生命活动起到调控作用。let-7a是let-7 miRNA家族成员之一,参与细胞的增殖、凋亡等生物学过程,且在多种癌症中发挥肿瘤抑制因子的作用。本文就let-7a及其靶基因在HCC中作用机制的研究进展作一综述。     

CircRNA在自身免疫疾病中的研究进展

Circular RNA(简称CircRNA)为一类新发现、长链非编码的内源性环状RNA分子,能够参与基因组转录及转录后水平的调节,竞争内源性RNA特异性结合miRNA,进而通过调控其活性影响下游靶基因的表达,参与发育、凋亡,影响诸多疾病的进程。最新的研究证实,CircRNA调控了类风湿性关节炎(rheumatoid arthritis,RA)、系统性红斑狼疮(systemic lupus erythematosus,SLE)、多发性硬化症(multiple sclerosis,MS)等自身免疫性疾病的发生,有望作为此类疾病诊断标志物或治疗靶标。本文就CircRNA的生物学特性及其在自身免疫性疾病中的研究状况作一综述。     

肿瘤转移抑制基因1及Gli1基因在子宫内膜腺癌细胞系中的表达

目的探讨肿瘤转移抑制基因1(metastasis suppressor 1,MTSS1)及Gli1基因在子宫内膜腺癌细胞系Ishikawa和HEC-1A中的m RNA的转录及蛋白表达水平。方法体外培养子宫内膜高分化腺癌细胞系Ishikawa和中分化腺癌细胞系HEC-1A细胞,采用RT-PCR和Western blot法分别检测两株癌细胞系中MTSS1和Gli1基因m RNA的转录及蛋白的表达水平。结果子宫内膜高分化腺癌细胞系Ishikawa中MTSS1基因m RNA的转录及蛋白的表达水平显著高于中分化细胞系HEC-1A(P0.05),Ishikawa细胞系中Gli1基因m RNA转录及蛋白表达水平显著低于HEC-1A细胞系(P0.05)。结论 MTSS1可能作为转移抑制基因,通过调控Sonic hedgehog(Shh)信号通路参与子宫内膜腺癌的发生发展,为进一步研究子宫内膜腺癌的发生发展机制奠定了基础。     

miR-497对非小细胞肺癌患者的诊断价值

微小RNA(miRNA)是一类非编码小分子RNA,长度为18～25个核苷酸,通过互补的碱基与特定m RNA的3’-非翻译区(3’-UTR)结合,进而使靶m RNA发生降解或影响其翻译,用于转录后水平调控基因的表达。不同或者相同的miRNA在不同肿瘤中表现出作用不一样,且涉及肿瘤的每个发展阶段。本研究旨在探讨miR-497在非小细胞肺癌患者组织中的表达情况及临床应用价值。方法:采用Real-time PCR法检测10例非小细胞肺癌患者组织及癌旁,比对其表达差异,同时绘制ROC曲线判断其诊断价值。结果:非小细胞肺癌患者中miR-497在肺癌组织中表达下调,可能与非小细胞肺癌的发生密切相关,进一步分析得出,miR-497可能会成为诊断非小细胞肺癌的早期诊断指标。     

线粒体能量代谢相关miRNA的研究进展

线粒体为真核细胞的能量工厂,其能量代谢与细胞凋亡、自噬和衰老等过程密切相关,在疾病的发生发展以及后续治疗中也发挥着重要作用。microRNAs(miRNAs)为一类广泛存在于真核生物中的单链RNA,可通过降解靶基因或抑制靶基因的翻译来调节蛋白表达。近年来多项研究表明,miRNA还可通过调节线粒体相关基因的表达,调控线粒体的结构及功能,影响线粒体的能量代谢。本文就miRNA的作用机制及其与线粒体能量代谢关系的研究进展作一综述。     

靶向果蝇Kr-h1基因的mi RNA预测及其生物信息学分析

目的预测靶向果蝇Kr-h1(Krǜppel homolog1)基因的miRNA,并对其生物学功能及相关生物信息学进行分析,为进一步研究miRNA通过调控Kr-h1的表达而参与保幼激素(juvenile hormone,JH)对果蝇变态发育的调控奠定基础。方法通过microT-CDS、Targetscan和miRanda在线预测网站,对靶向Kr-h1基因的miRNA进行预测,对预测得到的多个miRNA按靶向结合可能性的大小进行汇总,3个网站均能预测到的miRNA为交集miRNA,对交集miRNA的靶基因及Kr-h1基因进行生物信息学功能分析。结果 microT-CDS、Targetscan和miRanda分别预测到30、7和11个靶向Kr-h1的miRNA,其中交集miRNA有4个,为miR-8、miR-277、miR-927和miR-964。功能分析发现,交集miRNA的靶基因主要参与细胞过程、生物过程和代谢过程,Kr-h1基因主要与昆虫生长发育及生殖相关。结论潜在靶向Kr-h1的miRNA涉及多个生物学过程,与昆虫的生长发育密切相关。     

miRNA在几种动物应激中的研究进展

miRNA是一类内源性18～22个核苷酸的非编码小RNA分子,通过与靶mRNA的3′非翻译区(3′untran-slated region,UTR)结合来调节基因的表达。在动物的多种生理进程和疾病的发生发展中,miRNA均发挥着重要作用。应激是机体对外界环境变化而产生的一系列非特异性的应答反应,不同应激源的刺激会导致miRNA的表达发生改变。因此,探究miRNA在动物应激中的研究进展对畜牧业的发展具有重要意义。本文综述了应激相关miRNA的研究进展,以期从分子水平寻找预防和诊断动物应激的方案。     

膀胱癌患者着色性干皮病F蛋白的表达水平及其临床意义

目的检测膀胱癌患者着色性干皮病F蛋白(XPF)的表达水平,并探讨其临床意义。方法Trizol法提取25份膀胱癌组织及10份癌旁正常组织总RNA,经RT-PCR扩增后,以扩增产物为模板,经实时荧光定量PCR法检测XPF的表达水平。结果各基因扩增效率近似相等,且具有很好的特异性,膀胱癌组织中XPF基因的表达水平明显低于癌旁正常组织。结论XPF可能参与了膀胱癌的发生和发展过程,对膀胱癌的转移潜能及预后具有一定意义。     

DEAD-box RNA解旋酶3在肿瘤中作用机制的研究进展

DEAD-box RNA解旋酶(DEAD-box helicase,DDX)在RNA代谢过程中发挥多种功能,对转录、剪切、mRNA转出、翻译、核糖体合成及miRNA的调控均有一定影响,其对RNA代谢的影响可引起一系列疾病的产生。DEAD-box RNA解旋酶3(DDX3)是DDX家族重要的成员,在细胞周期阻滞、细胞增殖和凋亡中起重要作用。DDX3可在多种肿瘤组织中发生异常表达,影响肿瘤患者的生存和预后。本文就DDX3在肿瘤,如肺癌、结直肠癌、乳腺癌及肝癌中作用机制的研究进展作一综述。     

外周血miRNAs检测在骨肉瘤中的意义

骨肉瘤是多发于儿童及青少年的原发性骨恶性肿瘤。目前,骨肉瘤患者预后较差,尚缺少有效的肿瘤标志物。mi RNAs是一组可以在转录后水平调控蛋白表达的非编码小分子RNA。mi RNAs参与调控一系列生理过程及包括骨肉瘤在内的多种恶性肿瘤的发生和发展。近年来的研究显示,外周血mi RNAs水平与骨肉瘤的病情进展密切相关,并有望成为骨肉瘤诊断、疗效及预后评估的新型生化指标。现就mi RNA的分子生物学特征,外周血mi RNA检测在骨肉瘤诊断、治疗效果及预后评估等领域的价值作一综述。     

ADAR Enzyme and miRNA Story: A Nucleotide that Can Make the Difference

Adenosine deaminase acting on RNA (ADAR) enzymes convert adenosine (A) to inosine (I) in double-stranded (ds) RNAs. Since Inosine is read as Guanosine, the biological consequence of ADAR enzyme activity is an A/G conversion within RNA molecules. A-to-I editing events can occur on both coding and non-coding RNAs, including microRNAs (miRNAs), which are small regulatory RNAs of ~20–23 nucleotides that regulate several cell processes by annealing to target mRNAs and inhibiting their translation. Both miRNA precursors and mature miRNAs undergo A-to-I RNA editing, affecting the miRNA maturation process and activity. ADARs can also edit 3′ UTR of mRNAs, further increasing the interplay between mRNA targets and miRNAs. In this review, we provide a general overview of the ADAR enzymes and their mechanisms of action as well as miRNA processing and function. We then review the more recent findings about the impact of ADAR-mediated activity on the miRNA pathway in terms of biogenesis, target recognition, and gene expression regulation.     

Critical Roles of Circular RNA in Tumor Metastasis via Acting as a Sponge of miRNA/isomiR

Circular RNAs (circRNAs), a class of new endogenous non-coding RNAs (ncRNAs), are closely related to the carcinogenic process and play a critical role in tumor metastasis. CircRNAs can lay the foundation for tumor metastasis via promoting tumor angiogenesis, make tumor cells gain the ability of migration and invasion by regulating epithelial-mesenchymal transition (EMT), interact with immune cells, cytokines, chemokines, and other non-cellular components in the tumor microenvironment, damage the normal immune function or escape the immunosuppressive network, and further promote cell survival and metastasis. Herein, based on the characteristics and biological functions of circRNA, we elaborated on the effect of circRNA via circRNA-associated competing endogenous RNA (ceRNA) network by acting as miRNA/isomiR sponges on tumor angiogenesis, cancer cell migration and invasion, and interaction with the tumor microenvironment (TME), then explored the potential interactions across different RNAs, and finally discussed the potential clinical value and application as a promising biomarker. These results provide a theoretical basis for the further application of metastasis-related circRNAs in cancer treatment. In summary, we briefly summarize the diverse roles of a circRNA-associated ceRNA network in cancer metastasis and the potential clinical application, especially the interaction of circRNA and miRNA/isomiR, which may complicate the RNA regulatory network and which will contribute to a novel insight into circRNA in the future.     

Identification of Recurrent Mutations in the microRNA-Binding Sites of B-Cell Lymphoma-Associated Genes in Follicular Lymphoma

Follicular lymphoma (FL) is a common indolent B-cell lymphoma that can transform into the more aggressive transformed FL (tFL). However, the molecular process driving this transformation is uncertain. In this work, we aimed to identify microRNA (miRNA)-binding sites recurrently mutated in follicular lymphoma patients, as well as in transformed FL patients. Using whole-genome sequencing data from FL tumors, we discovered 544 mutations located in bioinformatically predicted microRNA-binding sites. We then studied these specific regions using targeted sequencing in a cohort of 55 FL patients, found 16 recurrent mutations, and identified a further 69 variants. After filtering for QC, we identified 21 genes with mutated miRNA-binding sites that were also enriched for B-cell-associated genes by Gene Ontology. Over 40% of mutations identified in these genes were present exclusively in tFL patients. We validated the predicted miRNA-binding sites of five of the genes by luciferase assay and demonstrated that the identified mutations in BCL2 and EZH2 genes impaired the binding efficiency of miR-5008 and miR-144 and regulated the endogenous levels of messenger RNA (mRNA).     

Is the Efficiency of RNA Silencing Evolutionarily Regulated?

Small interfering RNAs (siRNAs) and microRNAs (miRNAs) regulate gene expression in a sequence-specific manner. Genes with partial complementarity to siRNA/miRNA sequences in their 3′-untranslated regions (UTRs) are suppressed by a mechanism referred to as the siRNA off-target effect or miRNA-mediated RNA silencing. However, the determinants of such RNA silencing efficiency are poorly understood. Previously, I and co-workers reported that the efficiency of RNA silencing is strongly correlated with the thermodynamic stability of base pairing in the duplex formed within an siRNA/miRNA and between the seed region and its target mRNA. In this review, I first summarize our previous studies that identified the thermodynamic parameter to estimate the silencing efficiency using the calculated base pairing stability: siRNAs downregulate the expression of off-target genes depending on the stability of binding between the siRNA seed region (nucleotides 2–8) and off-target mRNAs, and miRNAs downregulate target mRNA expression depending on the stability of the duplex formed between the 5′ terminus of the miRNA and its target mRNA. I further discuss the possibility that such thermodynamic features of silencing efficiency may have arisen during evolution with increasing body temperature in various organisms.     

LncRNAs in Ovarian Cancer Progression,Metastasis, and Main Pathways: ceRNA and Alternative Mechanisms

Ovarian cancer (OvCa) develops asymptomatically until it reaches the advanced stages with metastasis, chemoresistance, and poor prognosis. Our review focuses on the analysis of regulatory long non-coding RNAs (lncRNAs) competing with protein-coding mRNAs for binding to miRNAs according to the model of competitive endogenous RNA (ceRNA) in OvCa. Analysis of publications showed that most lncRNAs acting as ceRNAs participate in OvCa progression: migration, invasion, epithelial-mesenchymal transition (EMT), and metastasis. More than 30 lncRNAs turned out to be predictors of survival and/or response to therapy in patients with OvCa. For a number of oncogenic (CCAT1, HOTAIR, NEAT1, and TUG1 among others) and some suppressive lncRNAs, several lncRNA/miRNA/mRNA axes were identified, which revealed various functions for each of them. Our review also considers examples of alternative mechanisms of actions for lncRNAs besides being ceRNAs, including binding directly to mRNA or protein, and some of them (DANCR, GAS5, MALAT1, and UCA1 among others) act by both mechanisms depending on the target protein. A systematic analysis based on the data from literature and Panther or KEGG (Kyoto Encyclopedia of Genes and Genomes) databases showed that a significant part of lncRNAs affects the key pathways involved in OvCa metastasis, EMT, and chemoresistance.