The BTB-zinc finger transcription factor abrupt acts as an epithelial oncogene in drosophila melanogaster through maintaining a progenitor-like cell state

The capacity of tumour cells to maintain continual overgrowth potential has been linked to the commandeering of normal self-renewal pathways. Using an epithelial cancer model in Drosophila melanogaster, we carried out an overexpression screen for oncogenes capable of cooperating with the loss of the epithelial apico-basal cell polarity regulator, scribbled (scrib), and identified the cell fate regulator, Abrupt, a BTB-zinc finger protein. Abrupt overexpression alone is insufficient to transform cells, but in cooperation with scrib loss of function, Abrupt promotes the formation of massive tumours in the eye/antennal disc. The steroid hormone receptor coactivator, Taiman (a homologue of SRC3/AIB1), is known to associate with Abrupt, and Taiman overexpression also drives tumour formation in cooperation with the loss of Scrib. Expression arrays and ChIP-Seq indicates that Abrupt overexpression represses a large number of genes, including steroid hormone-response genes and multiple cell fate regulators, thereby maintaining cells within an epithelial progenitor-like state. The progenitor-like state is characterised by the failure to express the conserved Eyes absent/Dachshund regulatory complex in the eye disc, and in the antennal disc by the failure to express cell fate regulators that define the temporal elaboration of the appendage along the proximo-distal axis downstream of Distalless. Loss of scrib promotes cooperation with Abrupt through impaired Hippo signalling, which is required and sufficient for cooperative overgrowth with Abrupt, and JNK (Jun kinase) signalling, which is required for tumour cell migration/invasion but not overgrowth. These results thus identify a novel cooperating oncogene, identify mammalian family members of which are also known oncogenes, and demonstrate that epithelial tumours in Drosophila can be characterised by the maintenance of a progenitor-like state

Traditions of research into interruptions in healthcare: A conceptual review

Background Researchers from diverse theoretical backgrounds have studied workplace interruptions in healthcare, leading to a complex and conflicting body of literature. Understanding pre-existing viewpoints may advance the field more effectively than attempts to remove bias from investigations. Objective To identify research traditions that have motivated and guided interruptions research, and to note research questions posed, gaps in approach, and possible avenues for future research. Methods A critical review was conducted of research on interruptions in healthcare. Two researchers identified core research communities based on the community’s motivations, philosophical outlook, and methods. Among the characteristics used to categorise papers into research communities were the predominant motivation for studying interruptions, the research questions posed, and key contributions to the body of knowledge on interruptions in healthcare. In cases where a paper approached an equal number of characteristics from two traditions, it was placed in a blended research community. Results A total of 141 papers were identified and categorised; all papers identified were published from 1994 onwards. Four principal research communities emerged: epidemiology, quality improvement, cognitive systems engineering (CSE), and applied cognitive psychology. Blends and areas of mutual influence between the research communities were identified that combine the benefits of individual traditions, but there was a notable lack of blends incorporating quality improvement initiatives. The question most commonly posed by researchers across multiple communities was: what is the impact of interruptions? Impact was measured as a function of task time or risk in the epidemiology tradition, situation awareness in the CSE tradition, or resumption lag (time to resume an interrupted task) in the applied cognitive psychology tradition. No single question about interruptions in healthcare was shared by all four of the core communities. Conclusions Much research on workplace interruptions in healthcare can be described in terms of fundamental values of four distinct research traditions and the communities that bring the values and methods: of those research traditions to their investigations. Blends between communities indicate that mutual influence has occurred as interruptions research has progressed. It is clear from this review that there is no single or privileged perspective to study interruptions. Instead, these findings suggest that researchers investigating interruptions in healthcare would benefit from being more aware of different perspectives from their own, especially when they consider workplace interventions to reduce interruptions

scribble mutants cooperate with oncogenic Ras or Notch to cause neoplastic overgrowth in Drosophila

Cancer is a multistep process involving cooperation between oncogenic or tumor suppressor mutations and interactions between the tumor and surrounding normal tissue. Here we present the first description of cooperative tumorigenesis in Drosophila, by using a system that mimics the development of tumors in mammals. We have used the MARCM system to generate mutant clones of the apical–basal cell polarity tumor suppressor gene, scribble, in the context of normal tissue. We show that scribble mutant clones in the eye disc exhibit ectopic expression of cyclin E and ectopic cell cycles, but do not overgrow due to increased cell death mediated by the JNK pathway and the surrounding wild-type tissue. In contrast, when oncogenic Ras or Notch is expressed within the scribble mutant clones, cell death is prevented and neoplastic tumors develop. This demonstrates, for the first time in Drosophila, that activated alleles of Ras and Notch can act as cooperating oncogenes in the development of epithelial tumors, and highlights the importance of epithelial polarity regulators in restraining oncogenes and preventing tumor formation

The BTB-zinc finger transcription factor abrupt acts as an epithelial oncogene in Drosophila melanogaster through maintaining a progenitor-like cell state

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al.The capacity of tumour cells to maintain continual overgrowth potential has been linked to the commandeering of normal self-renewal pathways. Using an epithelial cancer model in Drosophila melanogaster, we carried out an overexpression screen for oncogenes capable of cooperating with the loss of the epithelial apico-basal cell polarity regulator, scribbled (scrib), and identified the cell fate regulator, Abrupt, a BTB-zinc finger protein. Abrupt overexpression alone is insufficient to transform cells, but in cooperation with scrib loss of function, Abrupt promotes the formation of massive tumours in the eye/antennal disc. The steroid hormone receptor coactivator, Taiman (a homologue of SRC3/AIB1), is known to associate with Abrupt, and Taiman overexpression also drives tumour formation in cooperation with the loss of Scrib. Expression arrays and ChIP-Seq indicates that Abrupt overexpression represses a large number of genes, including steroid hormone-response genes and multiple cell fate regulators, thereby maintaining cells within an epithelial progenitor-like state. The progenitor-like state is characterised by the failure to express the conserved Eyes absent/Dachshund regulatory complex in the eye disc, and in the antennal disc by the failure to express cell fate regulators that define the temporal elaboration of the appendage along the proximo-distal axis downstream of Distalless. Loss of scrib promotes cooperation with Abrupt through impaired Hippo signalling, which is required and sufficient for cooperative overgrowth with Abrupt, and JNK (Jun kinase) signalling, which is required for tumour cell migration/invasion but not overgrowth. These results thus identify a novel cooperating oncogene, identify mammalian family members of which are also known oncogenes, and demonstrate that epithelial tumours in Drosophila can be characterised by the maintenance of a progenitor-like state. © 2013 Turkel et al.This work was supported by grants from the Australian National Health and Medical Research Council (NHMRC) to AMB (NHMRC Grants #350396 and #509051) and HER (NHMRC Senior research Fellowship B and NHMRC Grants #400211 and #628401), NIH grant (1R21CA098997-01) to HER, Peter MacCallum Cancer Center Internal Grant to HER, a Development Travel Award to NT, and a Spanish Ministry of Education and Science grant to MC (CSD2007-00008) to support the Bioinformatics Platform.Peer Reviewe

Drosophila cyclin E interacts with components of the Brahma complex

Cyclin E–Cdk2 is essential for S phase entry. To identify genes interacting with cyclin E, we carried out a genetic screen using a hypomorphic mutation of Drosophila cyclin E (DmcycE(JP)), which gives rise to adults with a rough eye phenotype. Amongst the dominant suppressors of DmcycE(JP), we identified brahma (brm) and moira (mor), which encode conserved core components of the Drosophila Brm complex that is highly related to the SWI–SNF ATP-dependent chromatin remodeling complex. Mutations in genes encoding other Brm complex components, including snr1 (BAP45), osa and deficiencies that remove BAP60 and BAP111 can also suppress the DmcycE(JP) eye phenotype. We show that Brm complex mutants suppress the DmcycE(JP) phenotype by increasing S phases without affecting DmcycE protein levels and that DmcycE physically interacts with Brm and Snr1 in vivo. These data suggest that the Brm complex inhibits S phase entry by acting downstream of DmcycE protein accumulation. The Brm complex also physically interacts weakly with Drosophila retinoblastoma (Rbf1), but no genetic interactions were detected, suggesting that the Brm complex and Rbf1 act largely independently to mediate G(1) arrest

BTB-Zinc Finger Oncogenes Are Required for Ras and Notch-Driven Tumorigenesis in <i>Drosophila</i>

<div><p>During tumorigenesis, pathways that promote the epithelial-to-mesenchymal transition (EMT) can both facilitate metastasis and endow tumor cells with cancer stem cell properties. To gain a greater understanding of how these properties are interlinked in cancers we used <i>Drosophila</i> epithelial tumor models, which are driven by orthologues of human oncogenes (activated alleles of Ras and Notch) in cooperation with the loss of the cell polarity regulator, <i>scribbled</i> (<i>scrib</i>). Within these tumors, both invasive, mesenchymal-like cell morphology and continual tumor overgrowth, are dependent upon Jun N-terminal kinase (JNK) activity. To identify JNK-dependent changes within the tumors we used a comparative microarray analysis to define a JNK gene signature common to both Ras and Notch-driven tumors. Amongst the JNK-dependent changes was a significant enrichment for BTB-Zinc Finger (ZF) domain genes, including <i>chronologically inappropriate morphogenesis</i> (<i>chinmo</i>). <i>chinmo</i> was upregulated by JNK within the tumors, and overexpression of <i>chinmo</i> with either <i>Ras^V12</i> or <i>N^intra</i> was sufficient to promote JNK-independent epithelial tumor formation in the eye/antennal disc, and, in cooperation with <i>Ras^V12</i>, promote tumor formation in the adult midgut epithelium. Chinmo primes cells for oncogene-mediated transformation through blocking differentiation in the eye disc, and promoting an escargot-expressing stem or enteroblast cell state in the adult midgut. BTB-ZF genes are also required for Ras and Notch-driven overgrowth of <i>scrib</i> mutant tissue, since, although loss of <i>chinmo</i> alone did not significantly impede tumor development, when loss of <i>chinmo</i> was combined with loss of a functionally related BTB-ZF gene, <i>abrupt</i>, tumor overgrowth was significantly reduced. <i>abrupt</i> is not a JNK-induced gene, however, Abrupt is present in JNK-positive tumor cells, consistent with a JNK-associated oncogenic role. As some mammalian BTB-ZF proteins are also highly oncogenic, our work suggests that EMT-promoting signals in human cancers could similarly utilize networks of these proteins to promote cancer stem cell states.</p></div

HScrib is a functional homologue of the Drosophila tumour suppressor Scribble

Scribble (scrib), discs large (dlg) and lethal giant larvae (lgl) encode proteins that regulate cell polarity and have been identified as neoplastic tumour suppressor genes in Drosophila melanogaster. Here, we have used the Drosophila model system to provide the first functional evidence that human Scribble (hScrib) can act as a tumour suppressor. We show that hScrib protein displays highly polarized localization in mammalian epithelial cells and colocalizes with mammalian Dlg, similar to D. melanogaster Scribble (DmScrib) distribution in Drosophila epithelium. Furthermore, hScrib can rescue the polarity and tumorous overgrowth defects of scrib mutant Drosophila. hScrib therefore can act as an effective tumour suppressor in vivo, regulating both apical-basal polarity and cellular proliferation in a manner similar to that of DmScrib in Drosophila. These data demonstrate that hScrib is a functional homologue of DmScrib and therefore predict an important role for hScrib in the suppression of mammalian tumorigenesis

Ab is expressed in <i>msn-lacZ</i> and <i>chinmo-lacZ</i> expressing tumor cells.

<p>Mosaic eye-antennal discs, anterior to the right (A) and attached to brain lobes (BL) (B-C). Clones are generated with <i>ey-FLP</i>, and are positively marked by GFP (green, or magenta when overlaid with white). Ab (A-C) expression is shown in cyan (red when overlaid with white, dark blue when overlaid with green or yellow when overlaid with white and green in the merges), <i>msn-lacZ</i> (A-B) and <i>chinmo-lacZ</i> (C) expression is shown by antibody detection of β-Galactosidase (white, or red when overlaid with cyan in the merges). Yellow scale bar corresponds to 40μm. (A-B) Ab is endogenously expressed in the anterior progenitor domain of the eye disc (A) and is present in basal and migrating cells (B) of <i>scrib</i>^<i>1</i><i>+ Ras</i>^<i>ACT</i> tumors. These same cells strongly express the JNK reporter <i>msn-lacZ</i> (A’, B’). See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132987#pone.0132987.s008" target="_blank">S8A Fig</a> for the endogenous expression of Ab in control eye/antennal discs. (C) The migrating <i>scrib</i>^<i>1</i> + <i>Raf</i>^<i>GOF</i> tumor cells express Ab and are also positive for <i>chinmo-lacZ</i> expression.</p

<i>chinmo</i> overexpression in eye-antennal disc clones cooperates with <i>Ras</i>^<i>ACT</i> or <i>N</i>^<i>ACT</i> to produce massive tumors.

<p>Larval mosaic eye-antennal discs attached to brain lobes (BL), anterior to the top, at day 5 (A-D) and day 9 (E-G). Clones are generated with <i>ey-FLP</i>, and are positively marked by GFP (green). Tissue morphology is shown with Phalloidin staining to highlight F-actin (red). The yellow scale bar corresponds to 40μm. (A-D) Control <i>FRT82B</i> eye-antennal disc clones (A), <i>UAS-N</i>^<i>ACT</i>-expressing clones (B), <i>UAS-Ras</i>^<i>ACT</i>-expressing clones (C) and <i>UAS-chinmo</i>^<i>FL</i>-expressing clones (D) are relatively normal in size at day 5 prior to pupariation. (E-F) Co-expressing <i>UAS-chinmo</i>^<i>FL</i> with <i>UAS-N</i>^<i>ACT</i> (E) or <i>UAS-Ras</i>^<i>ACT</i> (F) in eye-antennal disc clones blocks pupariation, and the clonal tissue massively overgrows throughout an extended larval stage of development. Clones of mutant tissue within the brain lobes also over-proliferate to greatly enlarge the brain lobes (F). (G) Co-expressing <i>UAS-bsk</i>^<i>DN</i> in <i>chinmo</i>^<i>FL</i> + <i>Ras</i>^<i>ACT</i> clones does not restore pupariation to the tumor-bearing larvae, and the mutant tissue overgrows throughout an extended larval stage of development.</p