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Toggweiler JR, Dixon K, Bryan K. Simulations of radiocarbon in a coarse-resolution world ocean model: 1. Steady state prebomb distributions. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/jc094ic06p08217] [Citation(s) in RCA: 247] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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247 |
3
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Stouffer RJ, Manabe S, Bryan K. Interhemispheric asymmetry in climate response to a gradual increase of atmospheric CO2. Nature 1989. [DOI: 10.1038/342660a0] [Citation(s) in RCA: 212] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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212 |
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Abstract
Atmospheric weather systems become unpredictable beyond a few weeks, but climate variations can be predictable over much longer periods because of the coupling of the ocean and atmosphere. With the use of a global coupled ocean-atmosphere model, it is shown that the North Atlantic may have climatic predictability on the order of a decade or longer. These results suggest that variations of the dominant multidecadal sea surface temperature patterns in the North Atlantic, which have been associated with changes in climate over Eurasia, can be predicted if an adequate and sustainable system for monitoring the Atlantic Ocean exists.
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Foley NH, Bray IM, Tivnan A, Bryan K, Murphy DM, Buckley PG, Ryan J, O'Meara A, O'Sullivan M, Stallings RL. MicroRNA-184 inhibits neuroblastoma cell survival through targeting the serine/threonine kinase AKT2. Mol Cancer 2010; 9:83. [PMID: 20409325 PMCID: PMC2864218 DOI: 10.1186/1476-4598-9-83] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 04/21/2010] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Neuroblastoma is a paediatric cancer of the sympathetic nervous system. The single most important genetic indicator of poor clinical outcome is amplification of the MYCN transcription factor. One of many down-stream MYCN targets is miR-184, which is either directly or indirectly repressed by this transcription factor, possibly due to its pro-apoptotic effects when ectopically over-expressed in neuroblastoma cells. The purpose of this study was to elucidate the molecular mechanism by which miR-184 conveys pro-apoptotic effects. RESULTS We demonstrate that the knock-down of endogenous miR-184 has the opposite effect of ectopic up-regulation, leading to enhanced neuroblastoma cell numbers. As a mechanism of how miR-184 causes apoptosis when over-expressed, and increased cell numbers when inhibited, we demonstrate direct targeting and degradation of AKT2, a major downstream effector of the phosphatidylinositol 3-kinase (PI3K) pathway, one of the most potent pro-survival pathways in cancer. The pro-apoptotic effects of miR-184 ectopic over-expression in neuroblastoma cell lines is reproduced by siRNA inhibition of AKT2, while a positive effect on cell numbers similar to that obtained by the knock-down of endogenous miR-184 can be achieved by ectopic up-regulation of AKT2. Moreover, co-transfection of miR-184 with an AKT2 expression vector lacking the miR-184 target site in the 3'UTR rescues cells from the pro-apoptotic effects of miR-184. CONCLUSIONS MYCN contributes to tumorigenesis, in part, by repressing miR-184, leading to increased levels of AKT2, a direct target of miR-184. Thus, two important genes with positive effects on cell growth and survival, MYCN and AKT2, can be linked into a common genetic pathway through the actions of miR-184. As an inhibitor of AKT2, miR-184 could be of potential benefit in miRNA mediated therapeutics of MYCN amplified neuroblastoma and other forms of cancer.
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Research Support, Non-U.S. Gov't |
15 |
127 |
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Miller-Delaney SFC, Bryan K, Das S, McKiernan RC, Bray IM, Reynolds JP, Gwinn R, Stallings RL, Henshall DC. Differential DNA methylation profiles of coding and non-coding genes define hippocampal sclerosis in human temporal lobe epilepsy. ACTA ACUST UNITED AC 2014; 138:616-31. [PMID: 25552301 DOI: 10.1093/brain/awu373] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Temporal lobe epilepsy is associated with large-scale, wide-ranging changes in gene expression in the hippocampus. Epigenetic changes to DNA are attractive mechanisms to explain the sustained hyperexcitability of chronic epilepsy. Here, through methylation analysis of all annotated C-phosphate-G islands and promoter regions in the human genome, we report a pilot study of the methylation profiles of temporal lobe epilepsy with or without hippocampal sclerosis. Furthermore, by comparative analysis of expression and promoter methylation, we identify methylation sensitive non-coding RNA in human temporal lobe epilepsy. A total of 146 protein-coding genes exhibited altered DNA methylation in temporal lobe epilepsy hippocampus (n = 9) when compared to control (n = 5), with 81.5% of the promoters of these genes displaying hypermethylation. Unique methylation profiles were evident in temporal lobe epilepsy with or without hippocampal sclerosis, in addition to a common methylation profile regardless of pathology grade. Gene ontology terms associated with development, neuron remodelling and neuron maturation were over-represented in the methylation profile of Watson Grade 1 samples (mild hippocampal sclerosis). In addition to genes associated with neuronal, neurotransmitter/synaptic transmission and cell death functions, differential hypermethylation of genes associated with transcriptional regulation was evident in temporal lobe epilepsy, but overall few genes previously associated with epilepsy were among the differentially methylated. Finally, a panel of 13, methylation-sensitive microRNA were identified in temporal lobe epilepsy including MIR27A, miR-193a-5p (MIR193A) and miR-876-3p (MIR876), and the differential methylation of long non-coding RNA documented for the first time. The present study therefore reports select, genome-wide DNA methylation changes in human temporal lobe epilepsy that may contribute to the molecular architecture of the epileptic brain.
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Research Support, Non-U.S. Gov't |
11 |
121 |
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Toggweiler JR, Dixon K, Bryan K. Simulations of radiocarbon in a coarse-resolution world ocean model: 2. Distributions of bomb-produced carbon 14. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/jc094ic06p08243] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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118 |
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Lynch J, Fay J, Meehan M, Bryan K, Watters KM, Murphy DM, Stallings RL. MiRNA-335 suppresses neuroblastoma cell invasiveness by direct targeting of multiple genes from the non-canonical TGF-β signalling pathway. Carcinogenesis 2012; 33:976-85. [PMID: 22382496 DOI: 10.1093/carcin/bgs114] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transforming growth factor-β (TGF-β) signaling regulates many diverse cellular activities through both canonical (SMAD-dependent) and non-canonical branches, which includes the mitogen-activated protein kinase (MAPK), Rho-like guanosine triphosphatase and phosphatidylinositol-3-kinase/AKT pathways. Here, we demonstrate that miR-335 directly targets and downregulates genes in the TGF-β non-canonical pathways, including the Rho-associated coiled-coil containing protein (ROCK1) and MAPK1, resulting in reduced phosphorylation of downstream pathway members. Specifically, inhibition of ROCK1 and MAPK1 reduces phosphorylation levels of the motor protein myosin light chain (MLC) leading to a significant inhibition of the invasive and migratory potential of neuroblastoma cells. Additionally, miR-335 targets the leucine-rich alpha-2-glycoprotein 1 (LRG1) messenger RNA, which similarly results in a significant reduction in the phosphorylation status of MLC and a decrease in neuroblastoma cell migration and invasion. Thus, we link LRG1 to the migratory machinery of the cell, altering its activity presumably by exerting its effect within the non-canonical TGF-β pathway. Moreover, we demonstrate that the MYCN transcription factor, whose coding sequence is highly amplified in a particularly clinically aggressive neuroblastoma tumor subtype, directly binds to a region immediately upstream of the miR-335 transcriptional start site, resulting in transcriptional repression. We conclude that MYCN contributes to neuroblastoma cell migration and invasion, by directly downregulating miR-335, resulting in the upregulation of the TGF-β signaling pathway members ROCK1, MAPK1 and putative member LRG1, which positively promote this process. Our results provide novel insight into the direct regulation of TGF-β non-canonical signaling by miR-335, which in turn is downregulated by MYCN.
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Research Support, Non-U.S. Gov't |
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117 |
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Foley NH, Bray I, Watters KM, Das S, Bryan K, Bernas T, Prehn JHM, Stallings RL. MicroRNAs 10a and 10b are potent inducers of neuroblastoma cell differentiation through targeting of nuclear receptor corepressor 2. Cell Death Differ 2011; 18:1089-98. [PMID: 21212796 DOI: 10.1038/cdd.2010.172] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
MicroRNAs function as negative regulators of posttranscriptional gene expression, having major roles in cellular differentiation. Several neuroblastoma cell lines can be induced to undergo differentiation by all-trans-retinoic acid (ATRA) and are used for modeling signaling pathways involved in this process. To identify miRNAs contributing to differentiation, we profiled 364 loci following ATRA treatment of neuroblastoma cell lines and found miR-10a and miR-10b to be highly overexpressed in SK-N-BE, LAN5 and SHSY-5Y. Ectopic overexpression of these miRNAs led to a major reprogramming of the transcriptome and a differentiated phenotype that was similar to that induced by ATRA in each of these cell lines. One of the predicted downregulated miR-10a/b targets was nuclear receptor corepressor 2 (NCOR2), a corepressor of gene transcription, which is known to suppress neurite outgrowth. NCOR2 was experimentally validated as a direct target of miR-10a/b, and siRNA-mediated inhibition of this mRNA alone resulted in neural cell differentiation. Moreover, induction of differentiation could be blocked by ectopic upregulation of NCOR2 using an expression construct lacking the miR-10a/b 3' untranslated region target site. We conclude that miR-10a/b has major roles in the process of neural cell differentiation through direct targeting of NCOR2, which in turn induces a cascade of primary and secondary transcriptional alterations, including the downregulation of MYCN.
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Research Support, Non-U.S. Gov't |
14 |
109 |
11
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Bray I, Bryan K, Prenter S, Buckley PG, Foley NH, Murphy DM, Alcock L, Mestdagh P, Vandesompele J, Speleman F, London WB, McGrady PW, Higgins DG, O'Meara A, O'Sullivan M, Stallings RL. Widespread dysregulation of MiRNAs by MYCN amplification and chromosomal imbalances in neuroblastoma: association of miRNA expression with survival. PLoS One 2009; 4:e7850. [PMID: 19924232 PMCID: PMC2773120 DOI: 10.1371/journal.pone.0007850] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 10/22/2009] [Indexed: 12/02/2022] Open
Abstract
MiRNAs regulate gene expression at a post-transcriptional level and their dysregulation can play major roles in the pathogenesis of many different forms of cancer, including neuroblastoma, an often fatal paediatric cancer originating from precursor cells of the sympathetic nervous system. We have analyzed a set of neuroblastoma (n = 145) that is broadly representative of the genetic subtypes of this disease for miRNA expression (430 loci by stem-loop RT qPCR) and for DNA copy number alterations (array CGH) to assess miRNA involvement in disease pathogenesis. The tumors were stratified and then randomly split into a training set (n = 96) and a validation set (n = 49) for data analysis. Thirty-seven miRNAs were significantly over- or under-expressed in MYCN amplified tumors relative to MYCN single copy tumors, indicating a potential role for the MYCN transcription factor in either the direct or indirect dysregulation of these loci. In addition, we also determined that there was a highly significant correlation between miRNA expression levels and DNA copy number, indicating a role for large-scale genomic imbalances in the dysregulation of miRNA expression. In order to directly assess whether miRNA expression was predictive of clinical outcome, we used the Random Forest classifier to identify miRNAs that were most significantly associated with poor overall patient survival and developed a 15 miRNA signature that was predictive of overall survival with 72.7% sensitivity and 86.5% specificity in the validation set of tumors. We conclude that there is widespread dysregulation of miRNA expression in neuroblastoma tumors caused by both over-expression of the MYCN transcription factor and by large-scale chromosomal imbalances. MiRNA expression patterns are also predicative of clinical outcome, highlighting the potential for miRNA mediated diagnostics and therapeutics.
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Research Support, Non-U.S. Gov't |
16 |
105 |
12
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Bryan K, Komro FG, Manabe S, Spelman MJ. Transient Climate Response to Increasing Atmospheric Carbon Dioxide. Science 1982; 215:56-8. [PMID: 17790468 DOI: 10.1126/science.215.4528.56] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The ocean's role in the delayed response of climate to increasing atmospheric carbon dioxide has been studied by means of a detailed three-dimensional climate model. A near-equilibrium state is perturbed by a fourfold, stepfunction increase in atmospheric carbon dioxide. The rise in the sea surface temperature was initially much more rapid in the tropics than at high latitudes. However, the fractional response, as normalized on the basis of the total difference between the high carbon dioxide and normal carbon dioxide climates, becomes almost uniform at all latitudes after 25 years. Because of the influence of a more rapid response over continents, the normalized response of the zonally averaged surface air temperature is faster and becomes nearly uniform with respect to latitude after only 10 years.
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Abstract
Of the writers known to have considered the problem, Hough alone has attempted to give a date for the whole area. He says that the process began with the active occupancy of the region by white men thirty years before the date of his address, or in 1875. However, the foregoing review of the existing evidence as to the date when trenching began in southwestern United States indicates that these changes were initiated at slightly different times in each stream and occupied a considerable period in their accomplishment. The change from aggradation and the building of flood plains to dissection and the formation of arroyos in many streams of southern Arizona can be confidently placed in the decade 1880 to 1890, although many tributary streams were not affected until the 90's and some are still undissected. The date in southern Utah, northern Arizona and southern Colorado is apparently earlier, and cutting probably began at some time after 1860. The evidence as to the Rio Puerco in north-central New Mexico is conflicting and needs review. The statements of the early explorers indicate that the arroyos were already well formed at the time of the American conquest in 1846 and 47.
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Ryan J, Tivnan A, Fay J, Bryan K, Meehan M, Creevey L, Lynch J, Bray IM, O'Meara A, Tracey L, Davidoff AM, Stallings RL. MicroRNA-204 increases sensitivity of neuroblastoma cells to cisplatin and is associated with a favourable clinical outcome. Br J Cancer 2012; 107:967-76. [PMID: 22892391 PMCID: PMC3464768 DOI: 10.1038/bjc.2012.356] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background: Neuroblastoma remains a major cause of cancer-linked mortality in children. miR-204 has been used in microRNA expression signatures predictive of neuroblastoma patient survival. The aim of this study was to explore the independent association of miR-204 with survival in a neuroblastoma cohort, and to investigate the phenotypic effects mediated by miR-204 expression in neuroblastoma. Methods: Neuroblastoma cell lines were transiently transfected with miR-204 mimics and assessed for cell viability using MTS assays. Apoptosis levels in cell lines were evaluated by FACS analysis of Annexin V-/propidium iodide-stained cells transfected with miR-204 mimics and treated with chemotherapy drug or vehicle control. Potential targets of miR-204 were validated using luciferase reporter assays. Results: miR-204 expression in primary neuroblastoma tumours was predictive of patient event-free and overall survival, independent of established known risk factors. Ectopic miR-204 expression significantly increased sensitivity to cisplatin and etoposide in vitro. miR-204 direct targeting of the 3′ UTR of BCL2 and NTRK2 (TrkB) was confirmed. Conclusion: miR-204 is a novel predictor of outcome in neuroblastoma, functioning, at least in part, through increasing sensitivity to cisplatin by direct targeting and downregulation of anti-apoptotic BCL2. miR-204 also targets full-length NTRK2, a potent oncogene involved with chemotherapy drug resistance in neuroblastoma.
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Research Support, Non-U.S. Gov't |
13 |
95 |
15
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Goenawan IH, Bryan K, Lynn DJ. DyNet: visualization and analysis of dynamic molecular interaction networks. Bioinformatics 2016; 32:2713-5. [PMID: 27153624 PMCID: PMC5013899 DOI: 10.1093/bioinformatics/btw187] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/04/2016] [Indexed: 11/12/2022] Open
Abstract
Summary: The ability to experimentally determine molecular interactions on an almost proteome-wide scale under different conditions is enabling researchers to move from static to dynamic network analysis, uncovering new insights into how interaction networks are physically rewired in response to different stimuli and in disease. Dynamic interaction data presents a special challenge in network biology. Here, we present DyNet, a Cytoscape application that provides a range of functionalities for the visualization, real-time synchronization and analysis of large multi-state dynamic molecular interaction networks enabling users to quickly identify and analyze the most ‘rewired’ nodes across many network states. Availability and Implementation: DyNet is available at the Cytoscape (3.2+) App Store (http://apps.cytoscape.org/apps/dynet). Contact: david.lynn@sahmri.com. Supplementary Information: Supplementary data are available at Bioinformatics online.
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Journal Article |
9 |
90 |
16
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Das S, Foley N, Bryan K, Watters KM, Bray I, Murphy DM, Buckley PG, Stallings RL. MicroRNA mediates DNA demethylation events triggered by retinoic acid during neuroblastoma cell differentiation. Cancer Res 2010; 70:7874-81. [PMID: 20841484 PMCID: PMC2955783 DOI: 10.1158/0008-5472.can-10-1534] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuroblastoma is an often fatal pediatric cancer arising from precursor cells of the sympathetic nervous system. 13-Cis retinoic acid is included in the treatment regimen for patients with high-risk disease, and a similar derivative, all-trans-retinoic acid (ATRA), causes neuroblastoma cell lines to undergo differentiation. The molecular signaling pathways involved with ATRA-induced differentiation are complex, and the role that DNA methylation changes might play are unknown. The purpose of this study was to evaluate the genome-wide effects of ATRA on DNA methylation using methylated DNA immunoprecipitation applied to microarrays representing all known promoter and CpG islands. Four hundred and two gene promoters became demethylated, whereas 88 were hypermethylated post-ATRA. mRNA expression microarrays revealed that 82 of the demethylated genes were overexpressed by >2-fold, whereas 13 of the hypermethylated genes were underexpressed. Gene ontology analysis indicated that demethylated and re-expressed genes were enriched for signal transduction pathways, including NOS1, which is required for neural cell differentiation. As a potential mechanism for the DNA methylation changes, we show the downregulation of methyltransferases, DNMT1 and DNMT3B, along with the upregulation of endogenous microRNAs targeting them. Ectopic overexpression of miR-152, targeting DNMT1, also negatively affected cell invasiveness and anchorage-independent growth, contributing in part to the differentiated phenotype. We conclude that functionally important, miRNA-mediated DNA demethylation changes contribute to the process of ATRA-induced differentiation resulting in the activation of NOS1, a critical determinant of neural cell differentiation. Our findings illustrate the plasticity and dynamic nature of the epigenome during cancer cell differentiation.
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research-article |
15 |
83 |
17
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Althoff K, Beckers A, Odersky A, Mestdagh P, Köster J, Bray IM, Bryan K, Vandesompele J, Speleman F, Stallings RL, Schramm A, Eggert A, Sprüssel A, Schulte JH. MiR-137 functions as a tumor suppressor in neuroblastoma by downregulating KDM1A. Int J Cancer 2013; 133:1064-73. [PMID: 23400681 DOI: 10.1002/ijc.28091] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 12/06/2012] [Indexed: 01/08/2023]
Abstract
Neuroblastoma is the most common extracranial solid tumor of childhood, and accounts for ∼15% of all childhood cancer deaths. The histone demethylase, lysine-specific demethylase 1 (KDM1A, previously known as LSD1), is strongly expressed in neuroblastomas, and overexpression correlates with poor patient prognosis. Inducing differentiation in neuroblastoma cells has previously been shown to down regulate KDM1A, and siRNA-mediated KDM1A knockdown inhibited neuroblastoma cell viability. The microRNA, miR-137, has been reported to be downregulated in several human cancers, and KDM1A mRNA was reported as a putative target of miR-137 in colon cancer. We hypothesized that miR-137 might have a tumor-suppressive role in neuroblastoma mediated via downregulation of KDM1A. Indeed, low levels of miR-137 expression in primary neuroblastomas correlated with poor patient prognosis. Re-expressing miR-137 in neuroblastoma cell lines increased apoptosis and decreased cell viability and proliferation. KDM1A mRNA was repressed by miR-137 in neuroblastoma cells, and was validated as a direct target of miR-137 using reporter assays in SHEP and HEK293 cells. Furthermore, siRNA-mediated KDM1A knockdown phenocopied the miR-137 re-expression phenotype in neuroblastoma cells. We conclude that miR-137 directly targets KDM1A mRNA in neuroblastoma cells, and activates cell properties consistent with tumor suppression. Therapeutic strategies to re-express miR-137 in neuroblastomas could be useful to reduce tumor aggressiveness.
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Research Support, Non-U.S. Gov't |
12 |
83 |
18
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Das S, Bryan K, Buckley PG, Piskareva O, Bray IM, Foley N, Ryan J, Lynch J, Creevey L, Fay J, Prenter S, Koster J, van Sluis P, Versteeg R, Eggert A, Schulte JH, Schramm A, Mestdagh P, Vandesompele J, Speleman F, Stallings RL. Modulation of neuroblastoma disease pathogenesis by an extensive network of epigenetically regulated microRNAs. Oncogene 2013; 32:2927-36. [PMID: 22797059 PMCID: PMC3477279 DOI: 10.1038/onc.2012.311] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 05/15/2012] [Accepted: 06/12/2012] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRNAs) contribute to the pathogenesis of many forms of cancer, including the pediatric cancer neuroblastoma, but the underlying mechanisms leading to altered miRNA expression are often unknown. Here, a novel integrated approach for analyzing DNA methylation coupled with miRNA and mRNA expression data sets identified 67 epigenetically regulated miRNA in neuroblastoma. A large proportion (42%) of these miRNAs was associated with poor patient survival when underexpressed in tumors. Moreover, we demonstrate that this panel of epigenetically silenced miRNAs targets a large set of genes that are overexpressed in tumors from patients with poor survival in a highly redundant manner. The genes targeted by the epigenetically regulated miRNAs are enriched for a number of biological processes, including regulation of cell differentiation. Functional studies involving ectopic overexpression of several of the epigenetically silenced miRNAs had a negative impact on neuroblastoma cell viability, providing further support to the concept that inactivation of these miRNAs is important for neuroblastoma disease pathogenesis. One locus, miR-340, induced either differentiation or apoptosis in a cell context dependent manner, indicating a tumor suppressive function for this miRNA. Intriguingly, it was determined that miR-340 is upregulated by demethylation of an upstream genomic region that occurs during the process of neuroblastoma cell differentiation induced by all-trans retinoic acid (ATRA). Further biological studies of miR-340 revealed that it directly represses the SOX2 transcription factor by targeting of its 3'-untranslated region, explaining the mechanism by which SOX2 is downregulated by ATRA. Although SOX2 contributes to the maintenance of stem cells in an undifferentiated state, we demonstrate that miR-340-mediated downregulation of SOX2 is not required for ATRA induced differentiation to occur. In summary, our results exemplify the dynamic nature of the miRNA epigenome and identify a remarkable network of miRNA/mRNA interactions that significantly contribute to neuroblastoma disease pathogenesis.
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Research Support, N.I.H., Extramural |
12 |
70 |
19
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De Preter K, Mestdagh P, Vermeulen J, Zeka F, Naranjo A, Bray I, Castel V, Chen C, Drozynska E, Eggert A, Hogarty MD, Izycka-Swieszewska E, London WB, Noguera R, Piqueras M, Bryan K, Schowe B, van Sluis P, Molenaar JJ, Schramm A, Schulte JH, Stallings RL, Versteeg R, Laureys G, Van Roy N, Speleman F, Vandesompele J. miRNA expression profiling enables risk stratification in archived and fresh neuroblastoma tumor samples. Clin Cancer Res 2011; 17:7684-92. [PMID: 22031095 DOI: 10.1158/1078-0432.ccr-11-0610] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE More accurate assessment of prognosis is important to further improve the choice of risk-related therapy in neuroblastoma (NB) patients. In this study, we aimed to establish and validate a prognostic miRNA signature for children with NB and tested it in both fresh frozen and archived formalin-fixed paraffin-embedded (FFPE) samples. EXPERIMENTAL DESIGN Four hundred-thirty human mature miRNAs were profiled in two patient subgroups with maximally divergent clinical courses. Univariate logistic regression analysis was used to select miRNAs correlating with NB patient survival. A 25-miRNA gene signature was built using 51 training samples, tested on 179 test samples, and validated on an independent set of 304 fresh frozen tumor samples and 75 archived FFPE samples. RESULTS The 25-miRNA signature significantly discriminates the test patients with respect to progression-free and overall survival (P < 0.0001), both in the overall population and in the cohort of high-risk patients. Multivariate analysis indicates that the miRNA signature is an independent predictor of patient survival after controlling for current risk factors. The results were confirmed in an external validation set. In contrast to a previously published mRNA classifier, the 25-miRNA signature was found to be predictive for patient survival in a set of 75 FFPE neuroblastoma samples. CONCLUSIONS In this study, we present the largest NB miRNA expression study so far, including more than 500 NB patients. We established and validated a robust miRNA classifier, able to identify a cohort of high-risk NB patients at greater risk for adverse outcome using both fresh frozen and archived material.
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Research Support, Non-U.S. Gov't |
14 |
69 |
20
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Charitou T, Bryan K, Lynn DJ. Using biological networks to integrate, visualize and analyze genomics data. Genet Sel Evol 2016; 48:27. [PMID: 27036106 PMCID: PMC4818439 DOI: 10.1186/s12711-016-0205-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/16/2016] [Indexed: 12/22/2022] Open
Abstract
Network biology is a rapidly developing area of biomedical research and reflects the current view that complex phenotypes, such as disease susceptibility, are not the result of single gene mutations that act in isolation but are rather due to the perturbation of a gene’s network context. Understanding the topology of these molecular interaction networks and identifying the molecules that play central roles in their structure and regulation is a key to understanding complex systems. The falling cost of next-generation sequencing is now enabling researchers to routinely catalogue the molecular components of these networks at a genome-wide scale and over a large number of different conditions. In this review, we describe how to use publicly available bioinformatics tools to integrate genome-wide ‘omics’ data into a network of experimentally-supported molecular interactions. In addition, we describe how to visualize and analyze these networks to identify topological features of likely functional relevance, including network hubs, bottlenecks and modules. We show that network biology provides a powerful conceptual approach to integrate and find patterns in genome-wide genomic data but we also discuss the limitations and caveats of these methods, of which researchers adopting these methods must remain aware.
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Review |
9 |
66 |
21
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Bryan K, Cunningham P, Bolshakova N. Application of simulated annealing to the biclustering of gene expression data. ACTA ACUST UNITED AC 2006; 10:519-25. [PMID: 16871720 DOI: 10.1109/titb.2006.872073] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In a gene expression data matrix, a bicluster is a submatrix of genes and conditions that exhibits a high correlation of expression activity across both rows and columns. The problem of locating the most significant bicluster has been shown to be NP-complete. Heuristic approaches such as Cheng and Church's greedy node deletion algorithm have been previously employed. It is to be expected that stochastic search techniques such as evolutionary algorithms or simulated annealing might improve upon such greedy techniques. In this paper we show that an approach based on simulated annealing is well suited to this problem, and we present a comparative evaluation of simulated annealing and node deletion on a variety of datasets. We show that simulated annealing discovers more significant biclusters in many cases. Furthermore, we also test the ability of our technique to locate biologically verifiable biclusters within an annotated set of genes.
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Research Support, Non-U.S. Gov't |
19 |
65 |
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Buckley PG, Alcock L, Bryan K, Bray I, Schulte JH, Schramm A, Eggert A, Mestdagh P, De Preter K, Vandesompele J, Speleman F, Stallings RL. Chromosomal and microRNA expression patterns reveal biologically distinct subgroups of 11q- neuroblastoma. Clin Cancer Res 2010; 16:2971-8. [PMID: 20406844 DOI: 10.1158/1078-0432.ccr-09-3215] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The purpose of this study was to further define the biology of the 11q- neuroblastoma tumor subgroup by the integration of array-based comparative genomic hybridization with microRNA (miRNA) expression profiling data to determine if improved patient stratification is possible. EXPERIMENTAL DESIGN A set of primary neuroblastoma (n = 160), which was broadly representative of all genetic subtypes, was analyzed by array-based comparative genomic hybridization and for the expression of 430 miRNAs. A 15-miRNA expression signature previously shown to be predictive of clinical outcome was used to analyze an independent cohort of 11q- tumors (n = 37). RESULTS Loss of 4p and gain of 7q occurred at a significantly higher frequency in the 11q- tumors, further defining the genetic characteristics of this subtype. The 11q- tumors could be split into two subgroups using a miRNA expression survival signature that differed significantly in clinical outcome and the overall frequency of large-scale genomic imbalances, with the poor survival subgroup having significantly more imbalances. miRNAs from the expression signature, which were upregulated in unfavorable tumors, were predicted to target downregulated genes from a published mRNA expression classifier of clinical outcome at a higher-than-expected frequency, indicating the miRNAs might contribute to the regulation of genes within the signature. CONCLUSION We show that two distinct biological subtypes of neuroblastoma with loss of 11q occur, which differ in their miRNA expression profiles, frequency of segmental imbalances, and clinical outcome. A miRNA expression signature, combined with an analysis of segmental imbalances, provides greater prediction of event-free survival and overall survival outcomes than 11q status by itself, improving patient stratification.
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Research Support, Non-U.S. Gov't |
15 |
64 |
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Bray I, Tivnan A, Bryan K, Foley NH, Watters KM, Tracey L, Davidoff AM, Stallings RL. MicroRNA-542-5p as a novel tumor suppressor in neuroblastoma. Cancer Lett 2011; 303:56-64. [PMID: 21310526 DOI: 10.1016/j.canlet.2011.01.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 01/05/2011] [Accepted: 01/19/2011] [Indexed: 01/31/2023]
Abstract
Several studies have implicated the dysregulation of microRNAs in neuroblastoma pathogenesis, an often fatal paediatric cancer arising from precursor cells of the sympathetic nervous system. Our group and others have demonstrated that lower expression of miR-542-5p is highly associated with poor patient survival, indicating a potential tumor suppressive function. Here, we demonstrate that ectopic over-expression of this miRNA decreases the invasive potential of neuroblastoma cell lines in vitro, along with primary tumor growth and metastases in an orthotopic mouse xenograft model, providing the first functional evidence for the involvement of miR-542-5p as a tumor suppressor in any type of cancer.
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Research Support, U.S. Gov't, Non-P.H.S. |
14 |
63 |
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Murphy DM, Buckley PG, Bryan K, Das S, Alcock L, Foley NH, Prenter S, Bray I, Watters KM, Higgins D, Stallings RL. Global MYCN transcription factor binding analysis in neuroblastoma reveals association with distinct E-box motifs and regions of DNA hypermethylation. PLoS One 2009; 4:e8154. [PMID: 19997598 PMCID: PMC2781550 DOI: 10.1371/journal.pone.0008154] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 11/09/2009] [Indexed: 01/19/2023] Open
Abstract
Background Neuroblastoma, a cancer derived from precursor cells of the sympathetic nervous system, is a major cause of childhood cancer related deaths. The single most important prognostic indicator of poor clinical outcome in this disease is genomic amplification of MYCN, a member of a family of oncogenic transcription factors. Methodology We applied MYCN chromatin immunoprecipitation to microarrays (ChIP-chip) using MYCN amplified/non-amplified cell lines as well as a conditional knockdown cell line to determine the distribution of MYCN binding sites within all annotated promoter regions. Conclusion Assessment of E-box usage within consistently positive MYCN binding sites revealed a predominance for the CATGTG motif (p<0.0016), with significant enrichment of additional motifs CATTTG, CATCTG, CAACTG in the MYCN amplified state. For cell lines over-expressing MYCN, gene ontology analysis revealed enrichment for the binding of MYCN at promoter regions of numerous molecular functional groups including DNA helicases and mRNA transcriptional regulation. In order to evaluate MYCN binding with respect to other genomic features, we determined the methylation status of all annotated CpG islands and promoter sequences using methylated DNA immunoprecipitation (MeDIP). The integration of MYCN ChIP-chip and MeDIP data revealed a highly significant positive correlation between MYCN binding and DNA hypermethylation. This association was also detected in regions of hemizygous loss, indicating that the observed association occurs on the same homologue. In summary, these findings suggest that MYCN binding occurs more commonly at CATGTG as opposed to the classic CACGTG E-box motif, and that disease associated over expression of MYCN leads to aberrant binding to additional weaker affinity E-box motifs in neuroblastoma. The co-localization of MYCN binding and DNA hypermethylation further supports the dual role of MYCN, namely that of a classical transcription factor affecting the activity of individual genes, and that of a mediator of global chromatin structure.
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Research Support, Non-U.S. Gov't |
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Borkman TJ, Kaskutas LA, Room J, Bryan K, Barrows D. An historical and developmental analysis of social model programs. J Subst Abuse Treat 1998; 15:7-17. [PMID: 9534122 DOI: 10.1016/s0740-5472(97)00244-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This review synthesizes the philosophy, development, history, and current status of the philosophy of social or community model of recovery and of Social Model Programs (SMPs) based on an analysis of the available literature, much of it outside traditional sources. The social-community model of recovery evolved out of Alcoholics Anonymous (AA), and has a distinctive program philosophy with different assumptions, knowledge, and practice than professionally based treatment models. SMPs began in the 1940s in California, evolving by the 1980s into a continuum of recovery services that are publicly funded, legally incorporated nonprofit organizations. The characteristics of SMPs are described and the range of services are presented, including social setting detoxification, residential recovery homes, non-residential neighborhood recovery centers and sober living houses. SMPs are staffed exclusively by recovering alcoholics and their structure is based on the 12 traditions of AA, which emphasize democratic group processes with shared and rotated leadership and a minimal hierarchy. Cost effectiveness data suggest that residential social model programs average approximately $2,700 per stay versus $4,400 for other residential approaches, yet may offer similar outcomes in terms of substance use and improvement employment or family function.
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Historical Article |
27 |
59 |