gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Screening for DNA methylation in brain tumors in children and infants

Meeting Abstract

  • S. Schlosser - Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin, Pädiatrische Hämatologie und Onkologie
  • J. Kreth - Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin, Pädiatrische Hämatologie und Onkologie
  • J. Mühlisch - Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin, Pädiatrische Hämatologie und Onkologie
  • M. Frühwald - Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin, Pädiatrische Hämatologie und Onkologie

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocMI.05-05

DOI: 10.3205/09dgnc196, URN: urn:nbn:de:0183-09dgnc1963

Published: May 20, 2009

© 2009 Schlosser et al.
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Outline

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Objective: The role of DNA methylation in epigenetic gene silencing and its usefulness as a clinical marker has been demonstrated over the last years. Our aim was to investigate genome-wide DNA methylation in high risk brain tumors of childhood to identify aberrantly methylated target genes.

Methods: We determined genome-wide DNA methylation in 10 medulloblastomas, 2 sPNET, 9 ependymomas and 4 tumor cell lines using Restriction Landmark Genomic Scanning (AscI-RLGS). A library-based cloning technique and VGS (Virtual Genome Scan) were used to identify candidate genes. DNA methylation of selected genes was evaluated in a larger cohort of tumors, tumor cell lines and control tissues by calibrated COBRA as well as direct and clonal bisulfite sequencing. Expression and re-expression studies were performed by RT-PCR and Real Time PCR.

Results: Based on the RLGS approach we identified 20 genes that are aberrantly methylated in pediatric brain tumors. As an example the elevated methylation of DRD4 was confirmed in different tumor entities (19 medulloblastomas, 37 ependymomas, 7 high grade gliomas, 10 sPNET) and 8 tumor cell lines when compared to normal cerebellum and cerebrum of children by COBRA. DRD4 hypermethylation was further confirmed by sequencing approaches. Significantly decreased expression was detected in ependymomas and sPNETs. We also see a reduced expression with borderline significance in MB and cell lines. Treatment of cell lines with 5-aza-2’ dexoycytidine (5-aza-CdR) and a combination of 5-aza-CdR and trichostatin A reactivated DRD4 expression in 6 MB cell lines.

Conclusions: We identified several aberrantly methylated genes in pediatric brain tumors. Detailed examination of such target genes demonstrated hypermethylation of e.g. DRD4. Current and intended investigations of epigenetic gene regulation and functional consequences of the disruption of our newly identified target genes as well as the correlation of clinical and experimental data are expected to elucidate the relevance of hypermethylation of these genes in pediatric brain tumors.