Unknown,Transcriptomics,Genomics,Proteomics

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Genome-wide methylation analyses in glioblastoma multiforme (GBM)

ABSTRACT: Our main objective was to study genome-wide differential methylation in de novo glioblastoma multiforme (GBM, grade IV glioma). We evaluated CpG sites in gene promoters of 26,000+ genes using an array-based chip. We retrieved 54 GBM from biorepositories of two institutions(40 from Columbia University and 14 from Case Western Reserve University) and 24 control brain tissues from the New York Brain Bank, which collected control brain tissues from consented subjects without history of neurological diseases at autopsy. Bisulfite modified DNA was extracted from 54 GBM and 24 control brain tissue. The HumanMethylation27 Analysis Bead-Chips (Illumina) were used to interrogate 26,486 informative CpG sites in the autosomes.

ORGANISM(S): Homo sapiens

SUBMITTER: Rose Lai

PROVIDER: E-GEOD-50923 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Glioblastoma multiforme (GBM) is the most aggressive and most lethal primary malignant brain tumor, correlated with survival rates of less than one year from the time of diagnosis. Current surgical procedure attempts to remove the bulk of the tumor mass, whereas GBM frequently recurs within 1-3cm from the primary tumor resection site. Molecular mechanisms involved in the recurrence of the tumor are still poorly understood. The aim of the study was to define the molecular signature of GBM surrounding white matter (WM) in order to better understand the molecular mechanisms involved with tumor relapse. Material & Methods: Human GBM tumor bulk and surrounding tissue (1-3cm from the border of the tumor) were obtained from five patients who underwent total tumour resection, while normal white matter was harvested from patients who underwent surgical procedure for nonmalignant pathologies. Samples were processed for hybridization on the Affymetrix Human U133A arrays and data were examined with the GeneSpring analysis software. Results: Gene expression analysis of the samples was done in 2 independent steps. First, molecular profiling comparison of GBM surrounding WM and normal WM resulted in 59 genes differentially expressed between both tissues. Among these, numerous genes expressed by mature neural cells were down-regulated in GBM surrounding WM, while gene products supporting invasion were overexpressed. Moreover, KLRC1, a specific natural killer receptor naturally involved in the activation of antitumoral cells was drastically repressed in GBM surrounding WM, suggesting that the antitumoral immune surveillance is compromised in this tissue. Second, we focused our study on genes specifically regulated in GBM periphery respectively to GBM core. The highest up-regulated gene in GBM surrounding tissue encodes for DTX4, a regulator of NOTCH signalling pathway described for its key role in maintaining neural progenitors in an uncommitted state. Conclusion: This study revealed unique molecular characteristics of GBM surrounding tissue, showing the dysregulation of genes involved in immune surveillance along with genes associated to stemness maintenance. All together, these data may help to understand the molecular mechanisms associated with GBM recurrence This study attempted to define the molecular characteristics of the GBM surrounding tissue. To this end, GBM tumor samples were obtained from 5 patients who underwent total tumor resection. Surrounding tumor mass tissue was retrieved in all cases from not infiltrated white matter sited at 2 cm from the macroscopic tumor border. Furthermore, control white matter biopsies were harvested from patients operated on for deep intracerebral cavernomas. Each sample was hybridized onto Affymetrix human U133 arrays. For each patient, tumor core sample and surrounding tissue were harvested and are identified with the same suffix number. In 2 cases, (patients 3 and 4), two tumor peripheral tissue samples were harvested and are identified with the same number followed by "R" (replicate).

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Genome-wide methylation analyses in glioblastoma multiforme (GBM)

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