1,720,979 research outputs found
Connecting epithelial polarity, proliferation and cancer in Drosophila: The many faces of lgl loss of function
No full textLoss of cell polarity is a prominent feature of epithelial cancers. Several tumour-suppressor genes are indeed involved in establishing and maintaining a correct apical-basal polarity suggesting that a link exists between disruption of epithelial polarity and the control of cell proliferation. Nevertheless, the molecular basis of this link is only beginning to be unveiled. In Drosophila, the tumour suppressor gene lethal giant larvae (lgl) is widely used as a genetic tool in cancer modelling: its loss of function causes neoplastic growth of the imaginal tissues, larval epithelial organs from which adult structures originate. These mutant epithelia are characterised by loss of cell polarity and tissue architecture as well as hyperproliferation. We observed that in a clonal context, the ability of lgl mutant cells to express their neoplastic potential correlates with the levels of the oncoprotein Myc, a master regulator of cell growth and proliferation. Malignant, polarity-deficient mutant cells upregulate Myc and are able to overcome the tumour-suppressive defences imposed by the surrounding wild-type tissue. How does the loss of lgl function induce an increase in Myc levels? The answer to this question came from the finding that Lgl is an upstream regulator of the Hippo pathway, a highly conserved signalling network that controls proliferation of epithelial cells and organ size. The core of this pathway responds to several upstream regulators and converges on the inhibition of a transcriptional co-factor, Yorkie, which, as we and others have shown, is a direct regulator of the myc promoter. In this review we discuss the key findings that contributed to the identification of this regulatory network that links cell polarity to cell proliferation control. © 2013 UBC Press
Multiple strategies of oxygen supply in Drosophila malignancies identify tracheogenesis as a novel cancer hallmark
Full text linkAngiogenesis is the term used to describe all the alterations in blood vessel growth induced by a tumour mass following hypoxic stress. The occurrence of multiple strategies of vessel recruitment favours drug resistance, greatly complicating the treatment of certain tumours. In Drosophila, oxygen is conveyed to the internal organs by the tracheal system, a closed tubular network whose role in cancer growth is so far unexplored. We found that, as observed in human cancers, Drosophila malignant cells suffer from oxygen shortage, release pro-tracheogenic factors, co-opt nearby vessels and get incorporated into the tracheal walls. We also found that the parallelisms observed in cellular behaviours are supported by genetic and molecular conservation. Finally, we identified a molecular circuitry associated with the differentiation of cancer cells into tracheal cells. In summary, our findings identify tracheogenesis as a novel cancer hallmark in Drosophila, further expanding the power of the fly model in cancer research
Multiple strategies of oxygen supply in Drosophila malignancies identify tracheogenesis as a novel cancer hallmark
Full text linkAngiogenesis is the term used to describe all the alterations in blood vessel growth induced by a tumour mass following hypoxic stress. The occurrence of multiple strategies of vessel recruitment favours drug resistance, greatly complicating the treatment of certain tumours. In Drosophila, oxygen is conveyed to the internal organs by the tracheal system, a closed tubular network whose role in cancer growth is so far unexplored. We found that, as observed in human cancers, Drosophila malignant cells suffer from oxygen shortage, release pro-tracheogenic factors, co-opt nearby vessels and get incorporated into the tracheal walls. We also found that the parallelisms observed in cellular behaviours are supported by genetic and molecular conservation. Finally, we identified a molecular circuitry associated with the differentiation of cancer cells into tracheal cells. In summary, our findings identify tracheogenesis as a novel cancer hallmark in Drosophila, further expanding the power of the fly model in cancer research
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
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