Neuroepithelial stem cell marker nestin regulates the migration, invasion and growth of human gliomas
ABSTRACT Nestin, a class VI intermediate filament protein, was originally described as a neuronal stem cell marker during central nervous system development. Nestin is expressed in gliomas, and its expression levels are higher in gliomas with high WHO histopathological classification grades than in those with low grades. In the present study, we examined whether nestin regulates the biological activities of human glioma cells. Immunohistochemically, the nestin expression patterns in 10 human glioblastoma patients were examined. The expression levels of nestin in A172, a human high-grade glioma cell line, and KG-1-C, a human low-grade glioma cell line, were examined using real-time PCR, Western blot and immunofluorescence analyses. An expression vector carrying a short hairpin RNA targeting nestin was stably transfected into A172 (Sh) cells. The effects of decreased expression levels of nestin in Sh cells on cell growth, migration, invasion, adhesion to extracellular matrices and fibrillar actin expression on three-dimensional culture plates were examined. The nestin expression vector was transiently transfected into KG-1-C (Nes) cells, and the effects of the nestin overexpression on cell growth and migration were examined. Nestin was expressed in the cytoplasm of the glioblastoma cells in all cases examined. Sh cells showed marked decreases in the expression levels of nestin mRNA and protein, and the growth rate of Sh cells was lower than that of sham (Sc) cells. In contrast, the adhesion activity of Sh cells to types I and IV collagens, fibronectin and laminin was higher than that of Sc cells. Fibrillar actin was clearly detected at the periphery of colonies of Sh cells at the attachment sites on three-dimensional culture plates. The migration and invasion of Sh cells were markedly inhibited compared with those of Sc cells. In contrast, the levels of nestin expression markedly increased in the Nes cells, which were transiently transfected with the nestin expression vector. The growth rate and motility of Nes cells were higher than those of the mock cells. In conclusion, nestin plays important roles in cell growth, migration, invasion and adhesion to extra-cellular matrices in glioma cells. Nestin may serve as a novel candidate for molecular-targeted therapy for gliomas, including glioblastomas.
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ABSTRACT: Cell migration is a multistep process which relies on the coordination of cytoskeletal structures in space and time. While the roles of actin and microtubules have been investigated in great details, the lack of inhibitors and visualizing tools and the large number of proteins forming intermediate filaments (IFs) have delayed the characterization of IF functions during migration. However, a large body of evidence has progressively pointed to changes in IF composition as an important parameter in the regulation of cell migratory properties both during development and tumor invasion. More recent in-depth analyses show that IFs are dynamically reorganized to participate, together with microfilaments and microtubules, to the key steps leading to cell migration. Copyright © 2015. Published by Elsevier Ltd.Current Opinion in Cell Biology 02/2015; 32C:102-112. DOI:10.1016/j.ceb.2015.01.005 · 8.74 Impact Factor
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ABSTRACT: Nestin, a class VI intermediate filament, was first described as a neuronal stem/progenitor cell marker. We previously reported that knockdown of nestin expression in human glioblastoma cells suppresses cell proliferation, migration, and invasion. In the present study, we examined the effect of nestin on stemness, and identified molecules involved in modulating nestin function in glioblastoma cells. Nestin expression was shown to be higher in high-grade gliomas than in low-grade gliomas. Furthermore, compared with control cells, nestin short hairpin RNA (shRNA)-transfected glioblastoma cells exhibited reduced sphere formation, decreased expression of NANOG, N-cadherin, CD133, and Oct-4, and decreased tumor size in vivo. To examine the proteins regulated by nestin in glioblastomas, we carried out two-dimensional electrophoresis using nestin shRNA-transfected glioblastoma cells. As a result, nestin shRNA-transfected glioblastoma cells exhibited a decrease in the level of phosphorylation of heat shock cognate 71 kDa protein (HSC71; gene HSPA8). From immunoprecipitation experiments, we demonstrated the direct binding of nestin, HSC71, and cyclin D1 in vitro. Overexpression of nestin in glioblastoma cells increased cell growth, sphere formation, and cell invasion. Transfection with HSC71 siRNA restored nestin expression and cell behavior; therefore, HSC71 knockdown will interfere with enhanced tumorigenic properties of glioblastoma cells that ectopically overexpress nestin. We have demonstrated that HSC71 and nestin regulate each other's expression levels or patterns, and that cyclin D1 is located downstream of nestin and HSC71. In conclusion, nestin regulates stemness, cell growth, and invasion in glioblastoma cells through the alteration of HSC71. Inhibition of nestin and HSC71 may thus be a useful molecular target in the treatment of glioblastomas. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.Cancer Letters 12/2014; 357(2). DOI:10.1016/j.canlet.2014.12.030 · 5.02 Impact Factor
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ABSTRACT: The cyclic-AMP response element binding (CREB) protein has been shown to have a pivotal role in cell survival and cell proliferation. Transgenic rodent models have revealed a role for CREB in higher-order brain functions, such as memory and drug addiction behaviors. CREB overexpression in transgenic animals imparts oncogenic properties on cells in various tissues, and aberrant CREB expression is associated with tumours. It is the central position of CREB, downstream from key developmental and growth signalling pathways, which gives CREB this ability to influence a spectrum of cellular activities, such as cell survival, growth and differentiation, in both normal and cancer cells. We show that CREB is highly expressed and constitutively activated in patient glioma tissue and that this activation closely correlates with tumour grade. The mechanism by which CREB regulates glioblastoma (GBM) tumour cell proliferation involves activities downstream from both the mitogen-activated protein kinase and phosphoinositide 3-kinase (PI3K) pathways that then modulate the expression of three key cell cycle factors, cyclin B, D and proliferating cell nuclear antigen (PCNA). Cyclin D1 is highly CREB-dependent, whereas cyclin B1 and PCNA are co-regulated by both CREB-dependent and -independent mechanisms. The precise regulatory network involved appears to differ depending on the tumour-suppressor phosphatase and tensin homolog status of the GBM cells, which in turn allows CREB to regulate the activity of the PI3K itself. Given that CREB sits at the hub of key cancer cell signalling pathways, understanding the role of glioma-specific CREB function may lead to improved novel combinatorial anti-tumour therapies, which can complement existing PI3K-specific drugs undergoing early phase clinical trials.06/2014; 3:e108. DOI:10.1038/oncsis.2014.21