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Expression data from U373 cells expressing EGFP, MAML1-dn and DTX1-myc

ABSTRACT: Glioblastoma multiforme (GBM) is the most malignant and most common tumor of the central nervous system characterized by rapid growth and extensive tissue infiltration. GBM results in more years of life lost than any other cancer type. Notch signaling has been implicated in GBM pathogenesis through several modes of action. Inhibition of Notch leads to a reduction of cancer-initiating cells in gliomas and reduces proliferation and migration. Deltex1 (DTX1) is part of an alternative Notch signaling pathway distinct from the canonical MAML1/RBP-Jκ-mediated cascade. In this study, we show that DTX1 activates both the RTK/PI3K/PKB as well as the MAPK/ERK pathway. Moreover, we found the anti-apoptotic factor Mcl-1 to be induced by DTX1. In accordance with this, the clonogenic potential and proliferation rates of glioma cell lines correlated with DTX1 levels. DTX1 knock down mitigated the tumorigenic potential in vivo, and overexpression of DTX1 increased cell migration and invasion of tumor cells accompanied by an elevation of the pro-migratory factors PKBβ and Snail1. Microarray gene expression analysis identified a DTX1-specific transcriptional program - including microRNA-21 - which is distinct from the canonical Notch signaling. We propose the alternative Notch pathway via DTX1 as oncogenic factor in malignant glioma and found low DTX1 expression levels to correlate with prolonged survival of GBM and early breast cancer patients in open source databases. We generated human glioma U373 cell lines stably expressing Enhanced Green Fluorescent Protein (EGFP), human Deltex1-Myc Tag (DTX1-myc), or Master Mind Like 1 - dominant negative (MAML1-dn) to compare differences in overall gene expression. We included 3x EGFP control samples, 3x DTX1-myc, and 3 MAML1-dn samples.

ORGANISM(S): Homo sapiens

SUBMITTER: Huber RM

PROVIDER: S-ECPF-GEOD-22772 | biostudies-other | 2013

REPOSITORIES: biostudies-other

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Project description:BACKGROUND: The tumor microenvironment is pivotal in tumor progression. Thus, we aimed to develop a mammary tumor model to elucidate molecular characteristics in the stroma versus the tumor cell compartment by global gene expression. Secondly, since tumor hypoxia influences several aspects of tumor pathophysiology, we hypothesized that hyperoxia might have an inhibitory effect on tumor growth per se. Finally, we aimed to identify differences in gene expression and key molecular mechanisms, both in the native state and following treatment. METHODS: 4T1 dsRed breast cancer cells were injected into eGFP expressing NOD/SCID mice. Group 1 was exposed to 3 intermittent HBO treatments (Day 1, 4 and 7), Group 2 to 7 daily HBO treatments (both 2.5 bar, 100% O?, à 90 min), whereas the controls were exposed to a normal atmosphere. Tumor growth, histology, vascularisation, cell proliferation, cell death and metastasis were assessed. Fluorescence-activated cell sorting was used to separate tumor cells from stromal cells prior to gene expression analysis. RESULTS: The purity of sorted cells was verified by fluorescence microscopy. Gene expression profiling demonstrated that highly expressed genes in the untreated tumor stroma included constituents of the extracellular matrix and matrix metalloproteinases. Tumor growth was significantly inhibited by HBO, and the MAPK pathway was found to be significantly reduced. Immunohistochemistry indicated a significantly reduced microvessel density after intermittent HBO, whereas daily HBO did not show a similar effect. The anti-angiogenic response was reflected in the expression trends of angiogenic factors. CONCLUSIONS: The present in vivo mammary tumor model enabled us to separate tumor and stromal cells, and demonstrated that the two compartments are characterized by distinct gene expressions, both in the native state and following HBO treatments. Furthermore, hyperoxia induced a significant tumor growth-inhibitory effect, with significant down-regulation of the MAPK pathway. An anti-angiogenic effect after intermittent HBO was observed, and reflected in the gene expression profile.

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Expression data from U373 cells expressing EGFP, MAML1-dn and DTX1-myc

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