1,721,188 research outputs found
p53 Modulates MYC-Mediated Cell Competition in Different Cancer Contexts
No full textCell competition was originally described in Drosophila as a physiological process based on the comparison of relative fitness between neighbouring cells. At the end of the process, suboptimal cells, called losers, are committed to die while stimulating proliferation of the most performant cells, called winners, so maintaining tissue homeostasis. In Drosophila and mammalian development, cells showing high MYC activity behave like winners, growing at the expense of the surrounding cells which succumb by apoptosis, so unveiling a leading role for this oncoprotein in eliciting cell competition. Since MYC protein is upregulated in a large fraction of human cancers, cell competition has been speculated to play a role in human tumourigenesis. Consistently with this hypothesis, we found massive apoptotic death of stromal cells in proximity to MYC-upregulating cancer cells in a relevant number of human tumour samples, and showed that modulation of MYC activity in human cancer cell lines is sufficient to subvert their competitive drive. In Drosophila, MYC-overexpressing cells have been demonstrated to be unable to execute cell competition in a p53 loss-of-function background. With the aim to find a role for p53 in MYC-mediated cell competition, we first stained the same cancer samples as above for p53. Interestingly, the tumour regions that did not show significant signs of competitive interactions were also found negative for p53 staining, disclosing a possible function for this protein in promoting cancer-associated cell competition. Further experiments in a¬ Drosophila cancer model helped us define a dose-dependent role of p53 in MYC-overexpressing winner cells, and functional assays in co-cultures of human cancer cells confirmed that p53 function is necessary for the winner cells to execute cell competition. Altogether, our findings reveal a pro-oncogenic role of p53, that appears to cooperate with MYC in driving cell competition in different cancer contexts
MYC-Mediated Cell Competition as an Evolutionary Trait of Cancer
Full text linkMYC-Mediated Cell Competition (MMCC) is a phenomenon of fitness comparison occurring between
adjacent cells showing different levels of MYC activity.. It describes a mechanism, conserved from
Drosophila to mammalian development, through which cells characterised by high expression of MYC
induce apoptotic death of neighbouring low MYC-expressing cells and acquire an advantage in space
occupancy. Though it is widely speculated that this phenomenon is relevant to cancer, its characterisation
during tumour progression is still missing.
Here we show the presence of markers of MMCC in human carcinomas and demonstrate through
experiments in human cancer cell lines that MYC modulation is per se sufficient to induce competitive
behaviours in both genetically distant and identical cells. Noteworthy, MYC inhibition in the fittest cell line
is sufficient to reverse its competitive status. Moreover, data obtained in a Drosophila,cancer model indicate
that MMCC is normally at work during tumour growth and that induction of high or low-MYC expressing
cells in the growing masses deeply alters the final tumour size, supporting a role for MMCC in cancer
evolution
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
The human protein Hugl-1 substitutes for Drosophila Lethal giant larvae tumour suppressor function in vivo
No full text
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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