Activation of canonical WNT/β-catenin signaling enhances in vitro motility of glioblastoma cells by activation of ZEB1 and other activators of epithelial-to-mesenchymal transition.

Division of Stereotactic Neurosurgery, Department of General Neurosurgery, University Medical Center Freiburg, Freiburg, Germany.
Cancer letters (Impact Factor: 5.02). 05/2012; 325(1):42-53. DOI: 10.1016/j.canlet.2012.05.024
Source: PubMed

ABSTRACT Here we show that activation of the canonical WNT/β-catenin pathway increases the expression of stem cell genes and promotes the migratory and invasive capacity of glioblastoma. Modulation of WNT signaling alters the expression of epithelial-to-mesenchymal transition activators, suggesting a role of this process in the regulation of glioma motility. Using immunohistochemistry in patient-derived glioblastoma samples we showed higher numbers of cells with intranuclear signal for β-catenin in the infiltrating edge of tumor compared to central tumor parenchyma. These findings suggest that canonical WNT/β-catenin pathway is a critical regulator of GBM invasion and may represent a potential therapeutic target.

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    ABSTRACT: Background The ubiquitous second messenger Ca2+ has been demonstrated to play an important role in cancer progression. Store-operated Ca2+ entry (SOCE) is the main Ca2+ entry pathway regulating intracellular Ca2+ concentration in a variety of cancer types. The present study aimed to explore the specific mechanisms of SOCE in the processes of glioma migration and invasion.Methods The expression of Orai1, a key component of SOCE, was examined in glioma samples and glioma cell lines by immunohistochemistry and western blot analysis. Both pharmacological intervention and RNA interference were employed to investigate the role of SOCE in glioma cell migration and invasion in vitro. The intracellular Ca2+ was certified through Fluo-4/AM based Ca2+ measurement. The effect of SOCE on cell viability, migration, and invasion was explored by methyl thiazolyl tetrazolium (MTT) assay, wound healing assay, transwell invasion assay. Western blot analysis and immunofluorescence assay were used to observe the changes of downstream related protein and cell morpholog.ResultsOrai1 expression was elevated in glioma tissues and several glioma cell lines compared with non-neoplastic brain tissues. Either inhibition of SOCE by a pharmacological inhibitor or Orai1 downregulation suppressed glioma cell migration and invasion. However, re-expression of Orai1 could rescue glioma cell motility. Furthermore, phosphorylation of proline-rich tyrosine kinase 2 (Pyk2) participated in the mechanisms by which SOCE regulated focal adhesion turnover and epithelial-to-mesenchymal (¿like) transition in glioma cells, both of which are considered to be critical for tumor progression.Conclusions The SOCE-Pyk2 pathway is essential for glioma migration and invasion. The study indicates the potential value of Orai1 as a molecular target for anti-invasion therapy.
    Journal of Experimental & Clinical Cancer Research 11/2014; 33(1):98. DOI:10.1186/PREACCEPT-3101393591453932 · 3.27 Impact Factor
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    ABSTRACT: Atypical teratoid/rhabdoid tumor (ATRT) is a malignant pediatric brain tumor with great recurrence after complete surgery and chemotherapy. Here, we demonstrate that cisplatin treatment selects not only for resistance but also for a more oncogenic phenotype characterized by high self-renewal and invasive capabilities. These phenomena are likely due to STAT3 upregulatoin which occurred simultaneously with higher expression of Snail, an activator of epithelial-mesenchymal transition (EMT), in ATRT-CisR cells. STAT3 knockdown effectively suppressed Snail expression and blocked motility and invasion in ATRT-CisR cells, while overexpressing Snail reversed these effects. Chromatin immunoprecipitation assay indicated that STAT3 directly bound to Snail promoter. Moreover, STAT3 knockdown effectively suppressed cancer stem-like properties, synergistically enhanced the chemotherapeutic effect, and significantly improved survival rate in ATRT-CisR-transplanted immunocompromised mice. Finally, immunohistochemistrical analysis showed that STAT3 and Snail were coexpressed at high levels in recurrent ATRT tissues. Thus, the STAT3/Snail pathway plays an important role in oncogenic resistance, rendering cells not only drug-resistant but also increasingly oncogenic (invasion, EMT and recurrence). Therefore, the STAT3/Snail could be a target for ATRT treatment.
    Oncotarget 12/2014; · 6.63 Impact Factor
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    ABSTRACT: Background Epidermal growth factor receptor (EGFR) and β-catenin are two key mediators of cell signal transduction implicated in the pathogenesis of a variety of tumors. There is emerging evidence indicating that they are overexpressed in glioblastoma multiforme (GBM) and both play significant roles in GBM carcinogenesis. Moreover, down-regulating EGFR individually only provides limited therapeutic efficacy. Therefore, we aimed to determine the feasibility and efficacy of gene therapy of GBM using combinatorial inhibition of EGFR and β-catenin in view of the cross-talk between these two signaling pathways. Methods The down-regulatory effect of small interfering RNA (siRNA) targeting EGFR and β-catenin alone or in combination in human GBM cells U-87 MG was evaluated by Quantitative RT-PCR. Cell proliferation in the short- and long-term was investigated by alamar blue and clonogenic assays, respectively. An annexin-V assay was performed to detect apoptosis caused by siRNA treatment. The effect of downregulating EGFR and β-catenin on cell cycle progression, cell migration and invasive potential were also examined. ResultsThe siRNA treatment potently reduced gene expression of EGFR and β-catenin at the mRNA level. Simultaneous inhibition of EGFR and β-catenin greatly decreased GBM cell proliferation. Although no significant increase in apoptosis was demonstrated, combinatorial siRNA treatment delayed the progression of cell cycle with an increased proportion of cells arrested in the G0/1 phase. Furthermore, EGFR and β-catenin siRNA in combination significantly inhibited the migratory and invasive ability of GBM cells. Conclusions Simultaneous inhibition of EGFR and β-catenin expression could represent an effective therapy for human GBM, and warrants further study in vivo. Copyright © 2013 John Wiley & Sons, Ltd.
    The Journal of Gene Medicine 01/2013; 15(1). DOI:10.1002/jgm.2693 · 1.95 Impact Factor


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