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Gene expression profiling in glioblastoma and immunohistochemical evaluation of IGFBP-2 and CDC20

ABSTRACT: The different clinical behavior of low and high grade gliomas and the chance to develop novel selective agents that specifically target tumor-associated proteins in gliomas stimulate the research of molecules playing a role in glioma progression. Gene expression profiling using microarrays allows the study at the same time of the expression patterns of thousands of genes in tumor cells. In the present study microarrays with about 20,000 genes have been employed to discover the gene expression profile in 39 glial neoplasias (28 glioblastomas (GBM) and 11 low grade gliomas, namely 4 oligodendrogliomas, 5 pilocytic astrocytomas (PA), 2 fibrillary astrocytomas (FA)). Unsupervised classification through hierarchical cluster analysis identified 2 groups of tumours: one group mainly composed of low grade malignant tumours (10 low grade gliomas and 3 GBM), the other one constituted by GBM, with the exception of one low grade case. The nearest shrunken centroid classification method was used to identify genes useful to classify and best characterize high and low grade gliomas. [Tibshirani et al. 2002] This procedure selected 9 genes as most informative for the classification task: Among them 7 genes were overexpressed in low grade gliomas, but underexpressed in GBM; on the contrary 2 genes were overexpressed in GBM, but underexpressed in low grade tumours Forty five tumors were immunostained for IGFBP-2 . 81,5% GBM resulted immunopositive. On the contrary only one low grade glioma was positive. Gene expression profiling and immunohistochemistry suggest that IGFBP-2 may play a role in glioma progression. IGFBP-2 appears to be a novel immunohistochemical marker of malignancy in glial tumours and probably is the basis for targeted chemotherapy. Keywords: glioblastoma, gene expression analysis, IGFBP-2, Hiearchical clustering

ORGANISM(S): Homo sapiens

PROVIDER: GSE9885 | GEO | 2007/12/19

SECONDARY ACCESSION(S): PRJNA103879

REPOSITORIES: GEO

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Project description:The different clinical behavior of low and high grade gliomas and the chance to develop novel selective agents that specifically target tumor-associated proteins in gliomas stimulate the research of molecules playing a role in glioma progression. Gene expression profiling using microarrays allows the study at the same time of the expression patterns of thousands of genes in tumor cells. In the present study microarrays with about 20,000 genes have been employed to discover the gene expression profile in 39 glial neoplasias (28 glioblastomas (GBM) and 11 low grade gliomas, namely 4 oligodendrogliomas, 5 pilocytic astrocytomas (PA), 2 fibrillary astrocytomas (FA)). Unsupervised classification through hierarchical cluster analysis identified 2 groups of tumours: one group mainly composed of low grade malignant tumours (10 low grade gliomas and 3 GBM), the other one constituted by GBM, with the exception of one low grade case. The nearest shrunken centroid classification method was used to identify genes useful to classify and best characterize high and low grade gliomas. [Tibshirani et al. 2002]; This procedure selected 9 genes as most informative for the classification task: ; Among them 7 genes were overexpressed in low grade gliomas, but underexpressed in GBM; on the contrary 2 genes were overexpressed in GBM, but underexpressed in low grade tumours; Forty five tumors were immunostained for IGFBP-2 . 81,5% GBM resulted immunopositive. On the contrary only one low grade glioma was positive. Gene expression profiling and immunohistochemistry suggest that IGFBP-2 may play a role in glioma progression. IGFBP-2 appears to be a novel immunohistochemical marker of malignancy in glial tumours and probably is the basis for targeted chemotherapy. Experiment Overall Design: We retrieved for this study 185 randomly selected cases of gliomas. All the cases had been received unfixed. A sample of neoplastic tissue had been flash frozen over liquid nitrogen and stored at -80Â°C into the frozen tissue bank of the Section of Pathology of Bellaria Hospital between 1990 and 2002. The remaining (specular) tissues were formalin fixed and paraffin embedded for routine histologic diagnosis. Experiment Overall Design: In the present investigation, only samples with rRNA 28S/18S ratio > 1.0 measured by Bioanalyzer 2100 (Agilent)and no evidence of ribosomal degradation were included. Some cases were excluded as the tissue samples were composed only by necrosis; other cases did not show neoplastic proliferation. Therefore only 39 glial neoplasias were suitable for the study: i.e. 28 GBMs and 11 low grade CNS tumors, namely 4 oligodendrogliomas (OL), 5 pilocytic astrocytomas (PA), 2 fibrillary astrocytoma (FA) showed a good quality of RNA. Experiment Overall Design: All the tumors were re-staged and graded according to 2000 WHO criteria at time of gene expression analysis by two pathologists (GM and VE). Experiment Overall Design: 39 glial neoplasias were labeled by Cy5. Common reference pool consisted of a mixture of total RNA from the low grade CNS tumor group (4 OL, 5 PA, 2 FA) labeled by Cy3. A series of the most informative genes were confirmed by RT-qPCR. Experiment Overall Design:

Project description:Background: Gliomas are the most common type of primary brain tumours, and in this group glioblastomas (GBMs) are the higher-grade gliomas with fast progression and unfortunate prognosis. Two major aspects of glioma biology that contributes to its awful prognosis are the formation of new blood vessels through the process of angiogenesis and the invasion of glioma cells. Despite of advances, two-year survival for GBM patients with optimal therapy is less than 30%. Even in those patients with low-grade gliomas, that imply a moderately good prognosis, treatment is almost never curative. Recent studies have demonstrated the existence of a small fraction of glioma cells with characteristics of neural stem cells which are able to grow in vitro forming neurospheres and that can be isolated in vivo using surface markers such as CD133. The aim of this study was to define the molecular signature of GBM cells expressing CD133 in comparison with non expressing CD133 cells. This molecular classification could lead to the finding of new potential therapeutic targets for the rationale treatment of high grade GBM. Methods: Eight fresh, primaries and non cultured GBMs were used in order to study the gene expression signatures from its CD133 positive and negative populations isolated by FACS-sorting. Dataset was generated with Affymetrix U133 Plus 2 arrays and analysed using the software of the Affymetrix Expression Console. In addition, genomic analysis of these tumours was carried out by CGH arrays, FISH studies and MLPA. Results: Gene expression analysis of CD133+ vs. CD133- cell population from each tumour showed that CD133+ cells presented common characteristics in all glioblastoma samples (up-regulation of genes involved in angiogenesis, permeability and down-regulation of genes implicated in cell assembly, neural cell organization and neurological disorders). Furthermore, unsupervised clustering of gene expression led us to distinguish between two groups of samples: those discriminated by tumour location and, the most importantly, the group discriminated by their proliferative potential. Conclusions: Primary glioblastomas could be sub-classified according to the properties of their CD133+ cells. The molecular characterization of these potential stem cell populations could be critical to find new therapeutic targets and to develop an effective therapy for these tumours with very dismal prognosis.

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Gene expression profiling in glioblastoma and immunohistochemical evaluation of IGFBP-2 and CDC20

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