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  • ACTIVATION  (11)
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  • 1
    Keywords: CANCER ; PATHWAY ; GENES ; ACTIVATION ; MUTATIONS ; SUBGROUPS ; LANDSCAPE ; TETRAPLOID TUMOR-CELLS ; TBR1
    Abstract: Medulloblastoma is an aggressively growing tumour, arising in the cerebellum or medulla/brain stem. It is the most common malignant brain tumour in children, and shows tremendous biological and clinical heterogeneity. Despite recent treatment advances, approximately 40% of children experience tumour recurrence, and 30% will die from their disease. Those who survive often have a significantly reduced quality of life. Four tumour subgroups with distinct clinical, biological and genetic profiles are currently identified. WNT tumours, showing activated wingless pathway signalling, carry a favourable prognosis under current treatment regimens. SHH tumours show hedgehog pathway activation, and have an intermediate prognosis. Group 3 and 4 tumours are molecularly less well characterized, and also present the greatest clinical challenges. The full repertoire of genetic events driving this distinction, however, remains unclear. Here we describe an integrative deep-sequencing analysis of 125 tumour-normal pairs, conducted as part of the International Cancer Genome Consortium (ICGC) PedBrain Tumor Project. Tetraploidy was identified as a frequent early event in Group 3 and 4 tumours, and a positive correlation between patient age and mutation rate was observed. Several recurrent mutations were identified, both in known medulloblastoma-related genes (CTNNB1, PTCH1, MLL2, SMARCA4) and in genes not previously linked to this tumour (DDX3X, CTDNEP1, KDM6A, TBR1), often in subgroup-specific patterns. RNA sequencing confirmed these alterations, and revealed the expression of what are, to our knowledge, the first medulloblastoma fusion genes identified. Chromatin modifiers were frequently altered across all subgroups. These findings enhance our understanding of the genomic complexity and heterogeneity underlying medulloblastoma, and provide several potential targets for new therapeutics, especially for Group 3 and 4 patients.
    Type of Publication: Journal article published
    PubMed ID: 22832583
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  • 2
    Keywords: RECEPTOR ; EXPRESSION ; KINASE ; PROTEIN ; ACTIVATION ; GLYCATION END-PRODUCTS ; OXIDATIVE STRESS ; p38 ; METHYLGLYOXAL INDUCES APOPTOSIS ; GLYOXAL
    Abstract: Tamoxifen is the standard adjuvant endocrine therapy for estrogen-receptor positive premenopausal breast cancer patients. However, tamoxifen resistance is frequently observed under therapy. A tamoxifen resistant cell line has been generated from the estrogen receptor positive mamma carcinoma cell line MCF-7 and was analyzed for putative differences in the aldehyde defence system and accumulation of advanced glycation end products (AGE). In comparison to wt MCF-7 cells, these tamoxifen resistant cells were more sensitive to the dicarbonyl compounds glyoxal and methylglyoxal and displayed increased caspase activity, p38-MAPK- and I kappa B alpha-phosphorylation. However, mRNA accumulation of the aldehyde-and AGE-defence enzymes glyoxalase-1 and -2 (GLO1, GLO2) as well as fructosamine-3-kinase (FN3K) was not significantly altered. Tamoxifen resistant cells contained less free sulfhydryl-groups (glutathione) suggesting that the increased sensitivity towards the dicarbonyls was due to a higher sensitivity towards reactive oxygen species which are associated with dicarbonyl stress. To further analyse, if these data are of more general importance, key experiments were replicated with tamoxifen resistant MCF-7 cell lines from two independent sources. These cell lines were also more sensitive to aldehydes, especially glyoxal, but were different in their cellular signalling responses to the aldehydes. In conclusion, glyoxalases and other aldehyde defence enzymes might represent a promising target for the therapy of tamoxifen resistant breast cancers.
    Type of Publication: Journal article published
    PubMed ID: 24983248
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  • 3
    Keywords: EXPRESSION ; GROWTH ; FACTOR RECEPTOR ; ACTIVATION ; TNF-ALPHA ; TUMOR-SUPPRESSOR ; MAMMARY-GLAND DEVELOPMENT ; TRANSDUCTION PATHWAYS ; MOLECULAR PORTRAITS ; OVARIAN-TUMORS
    Abstract: Nuclear Factor kappa B (NF-kappaB) signaling is frequently deregulated in a variety of cancers and is constitutively active in estrogen receptor negative (ER-) breast cancer subtypes. These molecular subtypes of breast cancer are associated with poor overall survival. We focused on mechanisms of NF-kappaB regulation by microRNAs (miRNAs), which regulate eukaryotic gene expression at the post-transcriptional level. In a previous genome-wide miRNA screen, we had identified miR-30c-2-3p as one of the strongest negative regulators of NF-kappaB signaling. Here we have uncovered the underlying molecular mechanisms and its consequences in breast cancer. In vitro results show that miR-30c-2-3p directly targets both TNFRSF1A-associated via death domain (TRADD), an adaptor protein of the TNFR/NF-kappaB signaling pathway, and the cell cycle protein Cyclin E1 (CCNE1). Ectopic expression of miR-30c-2-3p downregulated essential cytokines IL8, IL6, CXCL1, and reduced cell proliferation as well as invasion in MDA-MB-231 breast cancer cells. RNA interference (RNAi) induced silencing of TRADD phenocopied the effects on invasion and cytokine expression caused by miR-30c-2-3p, while inhibition of CCNE1 phenocopied the effects on cell proliferation. We further confirmed the tumor suppressive role of this miRNA using a dataset of 781 breast tumors, where higher expression was associated with better survival in breast cancer patients. In summary we have elucidated the mechanism by which miR-30c-2-3p negatively regulates NF-kappaB signaling and cell cycle progression in breast cancer.
    Type of Publication: Journal article published
    PubMed ID: 25732226
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  • 4
    Keywords: CANCER ; GROWTH ; INHIBITOR ; proliferation ; SURVIVAL ; tumor ; CELL-PROLIFERATION ; Germany ; KINASE ; INFORMATION ; TOOL ; DISEASE ; GENE ; GENES ; GENOME ; microarray ; PROTEIN ; PROTEINS ; transcription ; TUMORS ; RESOLUTION ; ACTIVATION ; DNA ; BIOLOGY ; cell cycle ; CELL-CYCLE ; CYCLE ; ASSOCIATION ; MOUSE ; IDENTIFICATION ; PROGRESSION ; ASSAY ; microarrays ; PROSTATE-CANCER ; STRATEGIES ; DNA-REPLICATION ; REPLICATION ; signaling ; RE ; TUMORIGENICITY ; genomics ; TRANSITION ; DNA replication ; C-ELEGANS ; cell proliferation ; PROTEIN-ANALYSIS ; development ; ASSAYS ; DIFFERENTIALLY EXPRESSED GENES ; high throughput ; HIGH-THROUGHPUT ; LONG ; PRIME ; PRINCIPLES ; REPRESSOR ; ROLES
    Abstract: Cancer transcription microarray studies commonly deliver long lists of "candidate" genes that are putatively associated with the respective disease. For many of these genes, no functional information, even less their relevance in pathologic conditions, is established as they were identified in large-scale genomics approaches. Strategies and tools are thus needed to distinguish genes and proteins with mere tumor association from those causally related to cancer. Here, we describe a functional profiling approach, where we analyzed 103 previously uncharacterized genes in cancer relevant assays that probed their effects on DNA replication (cell proliferation). The genes had previously been identified as differentially expressed in genome-wide microarray studies of tumors. Using an automated high-throughput assay with single-cell resolution, we discovered seven activators and nine repressors of DNA replication. These were further characterized for effects on extracellular signal-regulated kinase 1/2 (ERK1/2) signaling (G(1)-S transition) and anchorage-independent growth (tumorigenicity). One activator and one inhibitor protein of ERK1/2 activation and three repressors of anchorage-independent growth were identified. Data from tumor and functional profiling make these proteins novel prime candidates for further in-depth study of their roles in cancer development and progression. We have established a novel functional profiling strategy that links genomics to cell biology and showed its potential for discerning cancer relevant modulators of the cell cycle in the candidate lists from microarray studies
    Type of Publication: Journal article published
    PubMed ID: 16140941
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  • 5
    Keywords: proliferation ; PATHWAY ; GENES ; NF-KAPPA-B ; ACTIVATION ; SUPPRESSION ; METASTASIS ; CANCER-CELLS ; TRANSCRIPTIONAL REGULATION ; MIR-31
    Abstract: MicroRNAs post-transcriptionally regulate gene expression and thereby contribute to the modulation of numerous complex and disease-relevant cellular phenotypes, including cell proliferation, cell motility, apoptosis, and stress response. In breast cancer cell systems, miR-31 has been shown to inhibit cell migration, invasion, and metastasis. Here, we link enhanced expression of miR-31 to the inhibition of the oncogenic NF-kappaB pathway, thus supporting the tumor-suppressive function of this microRNA. We identified protein kinase C epsilon (PKCepsilon encoded by the PRKCE gene) as a novel direct target of miR-31 and show that down-regulation of PKCepsilon results in impaired NF-kappaB signaling, enhanced apoptosis, and increased sensitivity of MCF10A breast epithelial and MDA-MB-231 triple-negative breast cancer cells toward ionizing radiation as well as treatment with chemotherapeutics. Mechanistically, we attribute this sensitization to anti-cancer treatments to the PRKCE-mediated down-regulation of the anti-apoptotic factor BCL2. In clinical breast cancer samples, high BCL2 expression was associated with poor prognosis. Furthermore, we found an inverse correlation between miR-31 and BCL2 expression, highlighting the functional relevance of the indirect down-regulation of BCL2 via direct targeting of PRKCE by miR-31.
    Type of Publication: Journal article published
    PubMed ID: 23364795
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  • 6
    Keywords: CANCER ; CELLS ; ACTIVATION ; PROGRESSION ; TERM-FOLLOW-UP ; OSTEOPONTIN ; KIT ; PDGFRA MUTATIONS ; EPIGENETICS ; RECEPTOR-ALPHA MUTATIONS
    Abstract: Gastrointestinal stromal tumors (GISTs) have distinct gene expression patterns according to localization, genotype and aggressiveness. DNA methylation at CpG dinucleotides is an important mechanism for regulation of gene expression. We performed targeted DNA methylation analysis of 1.505 CpG loci in 807 cancer-related genes in a cohort of 76 GISTs, combined with genome-wide mRNA expression analysis in 22 GISTs, to identify signatures associated with clinicopathological parameters and prognosis. Principal component analysis revealed distinct DNA methylation patterns associated with anatomical localization, genotype, mitotic counts and clinical follow-up. Methylation of a single CpG dinucleotide in the non-CpG island promoter of SPP1 was significantly correlated with shorter disease-free survival. Hypomethylation of this CpG was an independent prognostic parameter in a multivariate analysis compared to anatomical localization, genotype, tumor size and mitotic counts in a cohort of 141 GISTs with clinical follow-up. The epigenetic regulation of SPP1 was confirmed in vitro, and the functional impact of SPP1 protein on tumorigenesis-related signaling pathways was demonstrated. In summary, SPP1 promoter methylation is a novel and independent prognostic parameter in GISTs, and might be helpful in estimating the aggressiveness of GISTs from the intermediate-risk category.
    Type of Publication: Journal article published
    PubMed ID: 25046773
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  • 7
    Keywords: APOPTOSIS ; CELLS ; EXPRESSION ; CELL ; Germany ; human ; SYSTEM ; DISEASE ; GENES ; GENOME ; PROTEIN ; PROTEINS ; ACTIVATION ; FLOW ; antibodies ; antibody ; IDENTIFICATION ; ASSAY ; CELL-DEATH ; fragmentation ; HUMAN GENOME ; FLUORESCENCE ; INHIBITORS ; CHEMISTRY ; RE ; flow cytometry ; genomics ; MEDIATED APOPTOSIS ; methods ; NUCLEAR ; USA ; function ; CANDIDATE ; microbiology ; caspase-3 ; cell-based assay ; PERMEABILITY TRANSITION PORE ; VIRUS CORE PROTEIN
    Abstract: After sequencing the human genome, the challenge ahead is to systematically analyze the functions and disease relation of the proteins encoded. Here the authors describe the application of a flow cytometry-based high-throughput assay to screen for apoptosis-activating proteins in transiently transfected cells. The assay is based on the detection of activated caspase-3 with a specific antibody, in cells overexpressing proteins tagged C- or N-terminally with yellow fluorescent protein. Fluorescence intensities are measured using a flow cytometer integrated with a high-throughput autosampler. The applicability of this screen has been tested in a pilot screen with 200 proteins. The candidate proteins were all verified in an independent microscopy-based nuclear fragmentation assay, finally resulting in the identification of 6 apoptosis inducers
    Type of Publication: Journal article published
    PubMed ID: 17478479
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  • 8
    Keywords: RECEPTOR ; CANCER ; EXPRESSION ; GROWTH ; GROWTH-FACTOR ; CELL ; Germany ; INHIBITION ; KINASE ; PATHWAY ; QUANTIFICATION ; SYSTEM ; SYSTEMS ; DISTINCT ; GENOME ; microarray ; PROTEIN ; PROTEINS ; SAMPLE ; SAMPLES ; ACTIVATION ; BIOLOGY ; MOLECULAR-BIOLOGY ; BREAST ; breast cancer ; BREAST-CANCER ; STIMULATION ; microarrays ; ARRAYS ; systems biology ; PROTEOMICS ; EPIDERMAL-GROWTH-FACTOR ; signaling ; molecular biology ; molecular ; RE ; ARRAY ; EGFR ; analysis ; methods ; HIGH-THROUGHPUT ; HER2 ; GEFITINIB ; comparison ; BREAST-CANCER-CELLS ; EGF ; ERK1/2 ; reverse phase protein array ; HER2/neu ; herceptin
    Abstract: Protein microarrays allow highly accurate comparison and quantification of numerous biological samples in parallel while requiring only little material. This qualifies protein arrays for systems biology and clinical research where only limited sample material is available, but a precise read-out is required. With the introduction of signal normalization steps to monitor the drop size of manually contact-spotted RP protein arrays, the usefulness of normalizer proteins to ensure a high-throughput but inexpensive protein analysis was demonstrated. This approach was applied for the analysis of signaling through ERBB receptor activated kinases in the breast cancer cell line MCF-7. Activation of ERK1/2 and AKT by ERBB1 (EGFR), ERRB2 (HER2/neu), and ERBB3-4 was monitored in a time-resolved manner. Analysis of pathway activation by stimulation with epidermal growth factor and heregulin, or inhibition by blocking with gefitinib or herceptin allowed a characterization of the distinct signaling properties of the different ERBB receptor subtypes
    Type of Publication: Journal article published
    PubMed ID: 18351692
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  • 9
    Keywords: APOPTOSIS ; CANCER ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; INVASION ; proliferation ; tumor ; CELL ; COMBINATION ; Germany ; KINASE ; POPULATION ; GENE ; GENES ; GENOME ; microarray ; ACTIVATION ; FAMILY ; REDUCTION ; CONTRAST ; BIOLOGY ; cell cycle ; CELL-CYCLE ; CYCLE ; PHOSPHORYLATION ; BREAST ; breast cancer ; BREAST-CANCER ; TARGET ; PROGRESSION ; ASSAY ; resistance ; TUMOR PROGRESSION ; METASTASIS ; genetics ; LINE ; REGION ; CANCER-CELLS ; REGIONS ; ONCOGENE ; sensitivity ; TARGETS ; OVEREXPRESSION ; LUCIFERASE ; ONCOLOGY ; TUMOR-SUPPRESSOR ; cell proliferation ; PHASE ; CELL-CYCLE ARREST ; MicroRNAs ; miRNA ; MICRORNA ; MESENCHYMAL TRANSITION ; CELL BIOLOGY ; tumor suppressor ; FAMILY-MEMBERS ; Genetic ; hypothesis ; REPORTER ; CONTRIBUTES ; miR-200 family ; PLC gamma 1
    Abstract: The genes encoding microRNAs of the human miR-200 family map to fragile chromosomal regions and are frequently downregulated upon tumor progression. Although having been reported to regulate epithelial-to-mesenchymal transition and transforming growth factor-beta- driven cell invasion, the role of the miR-200 family in EGF-driven breast cancer cell invasion, viability, apoptosis and cell cycle progression is still unknown. In particular, there is no study comparing the roles of the two clusters of this miRNA family. In this study, we show for the first time that miR-200 family members differentially regulate EGF-driven invasion, viability, apoptosis and cell cycle progression of breast cancer cells. We showed that, all miR-200 family members regulate EGF-driven invasion, with the miR-200bc/429 cluster showing stronger effects than the miR-200a/141 cluster. Furthermore, expression of the miR-200a/141 cluster results in G1 arrest supported by increased p27/Kip1 and decreased cyclin dependent kinase 6 expression. In contrast, expression of the 200bc/429 cluster decreases G1 population and increases G2/M phase, in line with the observed reduction of p27/Kip1 and upregulation of the inhibitory phosphorylation of Cdc25C, respectively. To test the hypothesis that phenotypical differences observed between the two clusters are caused by differential targeting spectrums, we performed genome-wide microarray profiling in combination with gain-of-function studies. This identified phospholipase C gamma 1 (PLCG1), which was downregulated only by the miR-200bc/429 cluster, as a potential candidate contributing to these phenotypical differences. Luciferase reporter assays validated PLCG1 as a direct functional target of miR-200bc/429 cluster, but not of miR-200a/141 cluster. Finally, loss of PLCG1 in part mimicked the effect of miR-200bc/429 overexpression in viability, apoptosis and EGF-driven cell invasion of breast cancer cells. Our results suggest that the miR-200 family has a tumor-suppressor function by negatively regulating EGF-driven cell invasion, viability and cell cycle progression in breast cancer. Oncogene (2010) 29, 4297-4306; doi: 10.1038/onc.2010.201; published online 31 May 2010
    Type of Publication: Journal article published
    PubMed ID: 20514023
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  • 10
    Keywords: CELLS ; ACTIVATION ; AMPLIFICATION ; ONCOGENE ; OVEREXPRESSION ; TYROSINE KINASES ; REGULATORY NETWORKS ; PERTURBATIONS ; HUMAN-BREAST-CANCER ; C-SRC
    Abstract: MOTIVATION: Network modelling in systems biology has become an important tool to study molecular interactions in cancer research, because understanding the interplay of proteins is necessary for developing novel drugs and therapies. De novo reconstruction of signalling pathways from data allows to unravel interactions between proteins and make qualitative statements on possible aberrations of the cellular regulatory program. We present a new method for reconstructing signalling networks from time course experiments after external perturbation and show an application of the method to data measuring abundance of phosphorylated proteins in a human breast cancer cell line, generated on reverse phase protein arrays. RESULTS: Signalling dynamics is modelled using active and passive states for each protein at each timepoint. A fixed signal propagation scheme generates a set of possible state transitions on a discrete timescale for a given network hypothesis, reducing the number of theoretically reachable states. A likelihood score is proposed, describing the probability of measurements given the states of the proteins over time. The optimal sequence of state transitions is found via a hidden Markov model and network structure search is performed using a genetic algorithm that optimizes the overall likelihood of a population of candidate networks. Our method shows increased performance compared with two different dynamical Bayesian network approaches. For our real data, we were able to find several known signalling cascades from the ERBB signalling pathway. AVAILABILITY: Dynamic deterministic effects propagation networks is implemented in the R programming language and available at http://www.dkfz.de/mga2/ddepn/.
    Type of Publication: Journal article published
    PubMed ID: 20823327
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