gms | German Medical Science

60. Jahrestagung der Deutschen Gesellschaft für Neuropathologie und Neuroanatomie (DGNN)

Deutsche Gesellschaft für Neuropathologie und Neuroanatomie

26. - 28.08.2015, Berlin

CNS germinomas are characterized by global demethylation, chromosomal instability and mutational activation of the Kit-, Ras/Raf/Erk- and Akt-pathways

Meeting Abstract

  • corresponding author presenting/speaker Torsten Pietsch - University of Bonn, Department of Neuropathology, Bonn, Germany
  • Laura Schulte - University of Bonn, Department of Neuropathology, Bonn, Germany
  • Barbara Steiger - University of Bonn, Department of Neuropathology, Bonn, Germany
  • Dorota Denkhaus - University of Bonn, Department of Neuropathology, Bonn, Germany
  • Christian Vokuhl - University of Kiel, Department of Pathology, Kiel, Germany
  • Ivo Leuschner - University of Kiel, Department of Pathology, Kiel, Germany

Deutsche Gesellschaft für Neuropathologie und Neuroanatomie. 60th Annual Meeting of the German Society for Neuropathology and Neuroanatomy (DGNN). Berlin, 26.-28.08.2015. Düsseldorf: German Medical Science GMS Publishing House; 2015. Doc15dgnnP48

doi: 10.3205/15dgnn72, urn:nbn:de:0183-15dgnn721

Veröffentlicht: 25. August 2015

© 2015 Pietsch et al.
Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). Lizenz-Angaben siehe http://creativecommons.org/licenses/by/4.0/.


Gliederung

Text

CNS germinomas represent a unique germ cell tumor entity characterized by uniform undifferentiated tumor cells and a high response rate to current treatment protocols. However, only limited information is available on their underlying genomic, epigenetic and biological alterations.

In this study we perfomed a genome-wide analysis of genomic copy number alteration and allelic disbalances in 37 cases of CNS germinomas by molecular inversion profiling. In addition, CpG dinucleotide methylation was studied by immunohistochemistry with a specific antibody against methylated cytosine residues. Mutational analysis was performed by resequencing of candidate genes including KIT and RAS family members using FFPE derived DNA. Ras/Erk and Akt pathway activation was analysed by immunostaining with specific antibodies against phospho-Erk and phospho-Akt.

All germinomas coexpressed Oct4 and Kit but showed an extensive global demethylation of nuclear DNA compared to other germ cell tumors and normal tissues. Molecular inversion profiling showed predominant genomic instability in 32/37 tumors with a high frequency of regional gains and losses including high level amplifications. Activating mutations of KIT exons 11, 13, 17 as well as a case with genomic KIT amplification and activating mutations or amplifications of RAS gene family members as well as mutation of BRAF indicated mutational activation of crucial signalling pathways. Activation of both, Ras/Erk and Akt pathways was demonstrated by immunohistochemistry of phospho-Erk and phospho-Akt in germinomas.

These data suggest that CNS germinoma cells display a demethylated nuclear DNA similar to primordial germ cells in early development. This finding is associated with extensive genomic instability in the majority of germinomas. In addition, mutational activation of KIT, Ras/Raf/Erk- and Akt- pathways is characteristic indicating the biological importance of these pathways and potential targets for therapy.