Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Identification of novel genes associated with human glioblastoma (GBM) tumor-initiating cells (TICs)

ABSTRACT: Most patients affected by Glioblastoma multiforme (GBM) experience a recurrence of the disease because of the spreading of tumor-initiating cells (TICs) beyond surgical boundary. Unveiling and targeting molecular mechanisms causing this process is a logic goal to impair GBM killing ability. In an orthotopic xenograph model, we have noticed that GBM TICs isolated from several patients may fall into two classes of invasive behavior: nodular or diffuse. In order to identify genes responsible for the diffusive type of invasion, we have compared by genome expression analysis, cultured GBM TICs belonging to the two classes. This analysis allowed us to identify a small group of regulated genes in the diffusive type of GBM TICs. The gene ontology process of cell adhesion and the localization of the gene product functions to the plasmamembrane resulted significantly associated to this gene set. Real time RT-PCR and immunofluorescence analyses performed for a selected subgroup of regulated genes/gene products confirmed the results obtained by the expression analysis. Some of the genes that we found upregulated in our screening were already proven to be involved in Glioma cell invasion supporting our study. However, we have also identified genes that were not previously implicated in this process. To assess whether these are required to sustain TICs GBM invasion, we silenced a subset of them and evaluated in Boyden chamber the invasive ability of the cells. Our study provides novel target genes to be evaluated for the inhibition of GBM diffusion within the SNC. As we observed that GBM TICs may fall into two classes of M-bM-^@M-^\in vivoM-bM-^@M-^] invasive behavior in mouse orthotopic transplantation: expansive or highly diffusive, resulting in the hostM-bM-^@M-^Ys white and gray matters substitution, we decided to identify genes associated with the latter phenotype by microarray analysis. Three replicates of each class were analyzed.

ORGANISM(S): Homo sapiens

SUBMITTER: Massimiliano Monticone

PROVIDER: E-GEOD-16805 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Identification of a novel set of genes reflecting different in vivo invasive patterns of human GBM cells.

Monticone Massimiliano M Daga Antonio A Candiani Simona S Romeo Francesco F Mirisola Valentina V Viaggi Silvia S Melloni Ilaria I Pedemonte Simona S Zona Gianluigi G Giaretti Walter W Pfeffer Ulrich U Castagnola Patrizio P

BMC cancer 20120817

<h4>Background</h4>Most patients affected by Glioblastoma multiforme (GBM, grade IV glioma) experience a recurrence of the disease because of the spreading of tumor cells beyond surgical boundaries. Unveiling mechanisms causing this process is a logic goal to impair the killing capacity of GBM cells by molecular targeting.We noticed that our long-term GBM cultures, established from different patients, may display two categories/types of growth behavior in an orthotopic xenograft model: expansion ...[more]

PMID: 22901239

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Project description:Glioblastomas (GBM) are poorly differentiated astrocytic tumors arising in the Central Nervous System (CNS), which despite aggressive treatments are still characterized by a fatal outcome. Several studies have shown the existence of a subpopulation of cells within glioma tumors displaying cancer stem cells properties. As the term âtumor initiating cellsâ (TICs) is frequentely used to describe cells as these with cancer stem cells capacity. Because TICs promotes the tumor chemo- and radio-resistance and angiogenesis it is conceivable that finding a mean to kill these cells would lead to a better therapy for GBM. The NOTCH gene has an important role during the CNS development, in the maintenance of dividing cells in promoting neural lineage entry of Embryonic Stem Cells and the differentiation of astroglia from the rat adult hippocampus-derived multipotent progenitors. The activation of the NOTCH signaling requires the proteolytic processing of this type I integral membrane protein by a two step process catalyzed first by a metalloprotease and then by the gamma-secretase. An increased activation of the NOTCH signaling has been implicated in several tumors types. Recently some studies showed that this pathway induces the survival/proliferation in GBM and glioma cells, and the expression of stem cell properties in glioma cells. Accordingly to these findings, the inhibition of this pathway leads to depletion of stem-like cells and blocks the engraftment in embryonal brain tumors. Furthermore, enhanced NOTCH signaling may lead to one of the tumor resistance mechanisms deployed by GBM. Targeting the NOTCH pathway specifically in GBM TICs appears therefore as a rational approach for exploring novel and hopefully more effective therapeutic strategies for the management of this malignancy. Several molecular tools are available for targeting the Notch pathway such as specific siRNAs, shRNAs or drugs such as gamma-secretase inhibitors. Among these tools, the latter are small peptides/molecules able to inhibit the gamma-secretase by distinct mechanisms. In this study we used two drugs known as gamma-secretase inhibitors, to investigate by gene expression profiling, their ability to interfere specifically with the proliferative properties of GBM TICs previously obtained in our laboratory. Our data show that one of these two drugs, LLNle, is effective in killing these cells in vitro by activating protein catabolic process mediated by the proteasome, suggesting that preclinical studies should definitely be carried on to evaluate whether LLNle is able to significantly improve the survival in hybrid human GBM-animal models. Gamma-secretase inhibitors have been proposed as drugs able to kill cancer cells by targeting the NOTCH pathway. In this study we employed two of such inhibitors, namely the z-Leu-leu-Nle-CHO (LLNle) and N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), to verify whether they were effective in vitro in the killing of human GBM tumor initiating cells (TICs). We first established that of the two drugs only LLNle reduces the viability of GBM TICs obtained from three different patients in the low micromolar range. Cells were treated with 7.5 Î¼M LLNle or DAPT or vehicle alone (DMSO 0.1%) and kept in a humidified 5% CO2 atmosphere at 37Â°C for the indicated time period (24 or 48 hours). To establish which cellular processes are activated in GBM TICs by LLNle we generated and analyzed the gene expression profile after treatment with this compound and with DAPT and DMSO (vehicle). Our data show that LLNle induces upregulation of genes coding for proteasome subunits and subsequently mitotic arrest in these cells by repressing genes required for DNA synthesis and mitotic progression and by activation of genes acting as mitotic inhibitors. Our data are consistent with proteasome inhibition by LLNle, subsequent upregulation of proteasome activity and subsequent unleash of the apoptotic process in GBM TICs.

Dataset Information

Identification of novel genes associated with human glioblastoma (GBM) tumor-initiating cells (TICs)

Publications

Identification of a novel set of genes reflecting different in vivo invasive patterns of human GBM cells.

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