An integrated analysis of miRNA and mRNA expressions in non-small cell lung cancers

Using DNA microarrays, we generated both mRNA and miRNA expression data from 6 non-small cell lung cancer (NSCLC) tissues and their matching normal control from adjacent tissues to identify potential miRNA markers for diagnostics. We demonstrated that hsa-miR-96 is significantly and consistently up-regulated in all 6 NSCLCs. We validated this result in an independent set of 35 paired tumors and their adjacent normal tissues, as well as their sera that are collected before surgical resection or chemotherapy, and the results suggested that hsa-miR-96 may play an important role in NSCLC development and has great potential to be used as a noninvasive marker for diagnosing NSCLC. We predicted potential miRNA target mRNAs based on different methods (TargetScan and miRanda). Further classification of miRNA regulated genes based on their relationship with miRNAs revealed that hsa-miR-96 and certain other miRNAs tend to down-regulate their target mRNAs in NSCLC development, which have expression levels permissive to direct interaction between miRNAs and their target mRNAs. In addition, we identified a significant correlation of miRNA regulation with genes coincide with high density of CpG islands, which suggests that miRNA may represent a primary regulatory mechanism governing basic cellular functions and cell differentiations, and such mechanism may be complementary to DNA methylation in repressing or activating gene expression.     

结肠癌中核内miRNA的激活调控作用研究

为了探究增强子介导的核内miRNA在结肠癌发生中的作用,本研究筛选了结肠癌中的差异表达的miRNA数据、结肠的特异性增强子数据、结肠癌中差异表达基因数据,利用细胞核内miRNA靶向增强子预测算法,筛选miRNA调控的结肠特异性增强子;利用增强子靶基因预测数据,筛选核内miRNA调控的差异表达靶基因,并且构建核内miRNA-靶基因网络,并通过网络的分析和筛选获得结肠癌中关键的致病基因,同时对网络中的靶基因进行GO的功能注释。结果表明,我们所构建的核内miRNA-激活调控靶基因网络包含miRNA-靶基因关系对2 121个,259个节点,其中包含34个下调基因、183个上调的基因,7个下调的miRNA,35个上调的miRNA。而后我们分析了网络进行的节点度的整体分布情况,发现网络中大部分的节点的度都是小于10的,仅有少量miRNA结合和部分的差异表达基因节点的度大于10。核内miRNA主要通过激活调控了一些应激反应相关的功能和,同时,抑制调控了细胞周期、细胞凋亡、细胞死亡巨噬细胞代谢等相关功能,通过激活和抑制相关功能诱发结肠癌的发生。从核内miRNA的激活调控角度研究结肠癌的发病机制,是对原有细胞浆中miRNA抑制调控机制的补充,也为结肠癌的系统研究提供了新的视野。     

The role of upregulated miRNAs and the identification of novel mRNA targets in prostatospheres

TICs are characterized by their ability to self-renew, differentiate and initiate tumor formation. miRNAs are small noncoding RNAs that bind to mRNAs resulting in regulation of gene expression and biological functions. The role of miRNAs and TICs in cancer progression led us to hypothesize that miRNAs may regulate genes involved in TIC maintenance. Using whole genome miRNA and mRNA expression profiling of TICs from primary prostate cancer cells, we identified a set of up-regulated miRNAs and a set of genes down-regulated in PSs. Inhibition of these miRNAs results in a decrease of prostatosphere formation and an increase in target gene expression. This study uses genome-wide miRNA profiling to analyze expression in TICs. We connect aberrant miRNA expression and deregulated gene expression in TICs. These findings can contribute to a better understanding of the molecular mechanisms governing TIC development/maintenance and the role that miRNAs have in the fundamental biology of TICs.     

Screening for possible miRNA–mRNA associations in a colon cancer cell line

MicroRNAs (miRNAs) are small non-coding RNAs mediating the regulation of gene expression in various biological contexts, including carcinogenesis. Here, we screened putative associations between 34, 45, and 103 miRNAs and 164, 391, and 81 mRNAs via Argonaute1 (Ago1) or Ago2 immunoprecipitation (IP) experiments in a colon cancer cell line. We used a combination of RIP Seq analysis. RNAs that were co-immunoprecipitated with Ago1 or Ago2 were used for massively parallel small RNA and mRNA sequencing. The detected miRNAs and mRNAs were further associated with one another based on in silico target predictions. Analysis of the putative associations indicated that, although Ago1 and Ago2 shared a similar repertory of miRNAs, the mRNAs possibly regulated by those miRNAs seemed different. The mRNAs detected with Ago1 IP were indicated to be frequently associated with genes having constitutive cellular functions, regulated by a smaller number of miRNAs, and appeared to receive more stringent translational regulation. In contrast, putative miRNA-mRNA associations detected with Ago2 IP appeared to be related to signal transduction genes, which had a larger number of possible miRNA binding sites. We then conducted a similar analysis using the colon cancer cells cultured under hypoxia and identified potential hypoxia-induced miRNA-mRNA associations, which included several well-characterized cancer-related genes as novel putative miRNA targets.     

MicroRNA and transcription factor co-regulatory network analysis reveals miR-19 inhibits CYLD in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy. The understanding of its gene expression regulation and molecular mechanisms still remains elusive. Started from experimentally verified T-ALL-related miRNAs and genes, we obtained 120 feed-forward loops (FFLs) among T-ALL-related genes, miRNAs and TFs through combining target prediction. Afterwards, a T-ALL miRNA and TF co-regulatory network was constructed, and its significance was tested by statistical methods. Four miRNAs in the miR-17-92 cluster and four important genes (CYLD, HOXA9, BCL2L11 and RUNX1) were found as hubs in the network. Particularly, we found that miR-19 was highly expressed in T-ALL patients and cell lines. Ectopic expression of miR-19 represses CYLD expression, while miR-19 inhibitor treatment induces CYLD protein expression and decreases NF-κB expression in the downstream signaling pathway. Thus, miR-19, CYLD and NF-κB form a regulatory FFL, which provides new clues for sustained activation of NF-κB in T-ALL. Taken together, we provided the first miRNA-TF co-regulatory network in T-ALL and proposed a model to demonstrate the roles of miR-19 and CYLD in the T-cell leukemogenesis. This study may provide potential therapeutic targets for T-ALL and shed light on combining bioinformatics with experiments in the research of complex diseases.     

Interactions of intergenic microRNAs with mRNAs of genes involved in carcinogenesis

miRNAs regulate gene expression by binding with mRNAs of many genes. Studying their effects on genes involved in oncogenesis is important in cancer diagnostics and therapeutics. The RNAHybrid 2.1 program was used to predict the strong miRNA binding sites (p < 0.0005) in target mRNAs. The program Finder 2.2 was created to verify 784 intergenic miRNAs (ig-miRNA) origin. Among 54 considered oncogenes and tumor suppressor genes, 47 genes are the best targets for ig-miRNAs. Accordingly, these genes are strongly regulated by 111 ig-miRNAs. Some miRNAs bind several mRNAs, and some mRNAs have several binding sites for miRNAs. Of the 54 mRNAs, 21.8%, 43.0%, and 35.2% of the miRNA binding sites are present in the 5'UTRs, CDSes, and 3'UTRs, respectively. The average density of the binding sites for miRNAs in the 5'UTR was 4.4 times and 4.1 times greater than in the CDS and the 3'UTR, respectively. Three types of interactions between miRNAs and mRNAs were identified, which differ according to the region of the miRNA bound to the mRNA: 1) binding occurs predominantly via the 3'-region of the miRNA; 2) binding occurs predominantly through the central region of the miRNA; and 3) binding occurs predominantly via the 5'-region of the miRNA. Several miRNAs effectively regulate only one gene, and this information could be useful in molecular medicine to modulate translation of the target mRNA. We recommend described new sites for validation by experimental investigation.