1,721,240 research outputs found
Abstract 929: Dissecting heterogeneity and population dynamics in breast cancer stem cells
No full textAbstract
The CSC hypothesis posits that there is a subset of tumors cells driving tumor growth and metastasis and that by targeting this population, tumors can be more efficiently eradicated. Recently it was shown that there are two types of CSCs in breast cancer, mesenchymal CSC’s characterized as CD44+/CD24- and an epithelial type marked by ALDH expression. The cellular plasticity of these CSC states may contribute to their metastatic capacity. However, little is known about the heterogeneity of these CSC populations or how they are regulated by the tumor microenvironment. To address these issues we have utilized Drop-Seq to generate single cell RNA-Seq data from thousands of cells across patient derived xenografts from various molecular subtypes of breast cancer. In order to monitor real-time state transitions between the determined cellular populations, we have also designed and constructed fluorescent reporter constructs for genes specific to critical cell populations and cancer stem cells. We used CRISPR/Cas9 to introduce these reporters into the native loci of the genes in order to recapitulate native gene expression patterns. Single cell transcriptomics will help to characterize the molecular heterogeneity of CSC populations. The addition of fluorescent reporters will help to elucidate the mechanisms that regulate breast CSC’s as well as their interaction with the tumor microenvironment and to identify potential therapeutic targets.
Citation Format: Michael D. Brooks, Max S. Wicha. Dissecting heterogeneity and population dynamics in breast cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 929. doi:10.1158/1538-7445.AM2017-929</jats:p
Abstract 939: Single cell mRNA expression profiling reveals heterogeneity of normal and malignant breast stem cell populations
No full textAbstract
The normal breast contains epithelial populations which are hierarchically organized, a profile recapitulated in breast cancer. At the apex of these hierarchies are "stem like" cells defined by their capacity to self-renew as well as to generate more differentiated progeny. In breast cancer these "cancer stem cells" (CSCs) have been shown to be important mediators of tumor metastasis and treatment resistance. Although the phenotypes of normal rodent and human mammary stem cells have been characterized, CSC populations are operationally defined by their capacity for tumor initiation. In addition, putative breast CSC markers such as CD44+/CD24low/- and or ALDH+ have proven useful in enriching for cells capable of tumor initiation and previous studies have suggested that these markers identify alternative mesenchymal and epithelial stem cell states, respectively. However, it remains unclear whether CSCs exist in discrete states or whether these cells actually represent a continuum reflected in heterogeneity of cell populations defined by expression of these markers. To address this question we utilized single cell mRNA expression profiling of normal and malignant breast stem cells. We first generated a panel of 96 genes representing stem cell and developmental pathways and analyzed expression of these 96 genes utilizing Fluidigm’s C1 and BioMark HD technologies and TaqMan gene expression assays. We also utilized Fluidigm’s Polaris to selectively isolate single cells that were then analyzed by illumina RNA-Seq method. Utilizing these advanced technologies, we demonstrated that both normal and malignant breast stem cells characterized by CD44+/CD24low/- and or ALDH+ expression are highly heterogeneous. For example, the ALDH isoforms ALDH1A1 and ALDH1A3 were each expressed in some single cells and co-expressed in others. ALDH1A1 expressing single cells appeared to express a unique gene pattern characterized by SLIT/ROBO, PLXNA2, RHOU and HNF1a. These results suggest that at the level of mRNA expression, normal and malignant breast stem cells display a greater heterogeneity than has previously been reported. These results have important implications for breast carcinogenesis as well as for the development of therapeutic strategies designed to target CSCs in breast cancer.
Citation Format: Shamileh Fouladdel, Justin Colacino, Ebrahim Azizi, Max S. Wicha. Single cell mRNA expression profiling reveals heterogeneity of normal and malignant breast stem cell populations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 939. doi:10.1158/1538-7445.AM2017-939</jats:p
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
Abstract 5909: Microfluidic vertical adhesion-suspension co-culture platform for studying cancer stem cell-fibroblast interactions
No full textAbstract
Considerable evidence suggests that cancer-stem-cells (CSCs) play critical roles in tumorigenesis and metastasis .Although surface marker expression or enzymatic activity of CSC has proven useful, variability of expression highlights the need for the development of high throughput functional CSC assays. One such approach utilizes the capability of CSC’s to form single-cell-derived spheres in suspension environments (functional CSCs). Microfluidic tools are suitable for handling and monitoring a large number of single cells in suspension as well as for examining the interaction of these cells with those in the tumor micro-environment including cancer associated fibroblasts (CAF’s).In order to accomplish this, we have developed a high-throughput (10,000-well), simple-to-use, vertical platform for CSC/CAF co-culture. The platform consists of a non-adherent substrate having 10,000 micro wells for single-cell-derived sphere formation and a porous trans well for CAF adherent co-culture. As predicted by Poisson’s distribution, approximately 30% of micro wells capture single cells when T47D breast cancer cells are loaded at a concentration of 200k/ml. After cell seeding, trans wells containing CAFs are placed onto the substrate. 0.4µm pores on the trans well allow for secretion-based cellular interaction while preventing direct CSC/CAF cell contact. This cell separation facilitates sample cell retrieval without cell cross contamination. Utilizing this device, we determined that co-culture of tumor cells with CAF’s doubled the frequency of sphere formation. Spheres derived from individual CSCs were then retrieved and dissociated for single-cell transcriptome analysis utilizing RNA barcoding followed by RNAseq. Molecular analysis revealed significant cellular heterogeneity among sphere derived cells. In addition, principal component analysis of single cell RNAseq, reveled significant differences in gene expression between mono-cultured and CAF co-cultured cells isolated from tumor spheres. These genes represent potential therapeutic targets for interfering with CSC stromal cell interactions in the tumor microenvironment. The vertical adhesion suspension co-culture platform provides a system to identify and evaluate novel CSC targeted therapeutics.
Citation Format: Yu-Chih Chen, Zhixiong Zhang, Yu-Heng Cheng, Euisik Yoon, Max S. Wicha. Microfluidic vertical adhesion-suspension co-culture platform for studying cancer stem cell-fibroblast interactions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5909. doi:10.1158/1538-7445.AM2017-5909</jats:p
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
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