1,721,455 research outputs found
Regulation of adenovirus replication by miR-199 confers a selective oncolytic activity in hepatocellular carcinoma
No full textOncolytic virotherapy represents a growing field of experimental cancer therapy. For safe and effective virotherapy, restricted tissue expression and replication of the virus is desirable. Various methods have been developed to achieve such restricted expression. They included the engineering of viral genomes through the insertion of tissue-specific promoters or genes encoding for tissue specific binding proteins. Here, we employed a new approach based on the use of microRNAs (miRNAs) to achieve tumor-specific viral expression and replication. miRNAs are approximately 22-nucleotide (nt)- long non-coding RNAs that are able to bind the 3’ untranslated regions (UTRs) of homologous target mRNAs and causing either their degradation or translation inhibition. Since miRNA are differentially expressed in cancer versus normal cells, it is theoretically possible to make virus expression restricted to cancer cells in a miRNA-dependent manner.
Several studies have shown that miR-199 is significantly down-regulated in primary hepatocellular carcinoma (HCC) tissue and HCC cell lines. With this notion in mind, we developed a conditionally replication-competent oncolytic adenovirus, Ad-199T, by introducing four copies of miR-199 target sites within the 3′ UTR of the E1A gene, which is essential for adenovirus replication.
In vitro studies of the properties of Ad-199T virus revealed that E1A expression was indeed tightly regulated both at RNA and protein levels depending upon the expression of miR-199. Consequently, Ad-199T could replicate in the HCC derived cells HepG2, negative for miR-199 expression, while its replication was strictly controlled in HepG2-199 cells, which were engineered to express high level of miR-199. A replication-competent miRNA independent Ad-Control was also generated,. Thus, these in vitro studies proved that cytotoxicity of Ad-199T was effective in HCC derived cells, which lacks expression of miR-199, and could be successfully controlled in cells that express miR-199 at high level.
To assess in vivo properties of Ad-199T, we tested an orthotopic tumor model. HepG2 cells were implanted in the liver of newborn B6D2 mice. The cells could survive at least one week in this environment, enough for testing in vivo properties of Ad-199T. These studies revealed that intrahepatic delivery of Ad-199T led to virus replication in HepG2 derived xenograft tumors and a faster removal of cancer cells. Conversely, Ad-199T replication was not detected in normal, miR-199 positive, liver parenchyma.
These results demonstrate that Ad-199T is a conditionally replicative adenovirus (CRAd) miR-199 dependent, with antitumor activity in vivo. This system allows replication of the oncolytic virus in HCC cells and, at the same time, tightly control replication in normal liver tissues, thus avoiding or reducing hepatotoxicity
Downregulation of miR-99a/let-7c/miR-125b miRNA cluster predicts clinical outcome in patients with unresected malignant pleural mesothelioma
Get PDFMalignant pleural mesothelioma (MPM) is an aggressive tumor with a dismal overall survival (OS) and to date no molecular markers are available to guide patient management. This study aimed to identify a prognostic miRNA signature in MPM patients who did not undergo tumor resection. Whole miRNA profiling using a microarray platform was performed using biopsies on 27 unresected MPM patients with distinct clinical outcome: 15 patients had short survival (OS < 12 months) and 12 patients had long survival (OS > 36 months). Three prognostic miRNAs (mir- 99a, let-7c, and miR-125b) encoded at the same cluster (21q21) were selected for further validation and tested on publicly available miRNA sequencing data from 72 MPM patients with survival data. A risk model was built based on these 3 miRNAs that was validated by quantitative PCR in an independent set of 30 MPM patients. High-risk patients had shorter median OS (7.6 months) as compared with low-risk patients (median not reached). In the multivariate Cox model, a high-risk score was independently associated with shorter OS (HR=3.14; 95% CI, 1.18-8.34; P=0.022). Our study identified that the downregulation of the miR-99a/let-7/miR-125b miRNA cluster predicts poor outcome in unresected MPM
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Trim25 is an RNA-specific activator of Lin28a/TuT4-mediated uridylation
Get PDFRNA binding proteins have thousands of cellular RNA targets and often exhibit opposite or passive molecular functions. Lin28a is a conserved RNA binding protein involved in pluripotency and tumorigenesis that was previously shown to trigger TuT4-mediated pre-let-7 uridylation, inhibiting its processing and targeting it for degradation. Surprisingly, despite binding to other pre-microRNAs (pre-miRNAs), only pre-let-7 is efficiently uridylated by TuT4. Thus, we hypothesized the existence of substrate-specific cofactors that stimulate Lin28a-mediated pre-let-7 uridylation or restrict its functionality on non-let-7 pre-miRNAs. Through RNA pull-downs coupled with quantitative mass spectrometry, we identified the E3 ligase Trim25 as an RNA-specific cofactor for Lin28a/TuT4-mediated uridylation. We show that Trim25 binds to the conserved terminal loop (CTL) of pre-let-7 and activates TuT4, allowing for more efficient Lin28a-mediated uridylation. These findings reveal that protein-modifying enzymes, only recently shown to bind RNA, can guide the function of canonical ribonucleoprotein (RNP) complexes in cis, thereby providing an additional level of specificity.</p
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