gms | German Medical Science

61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

The role of MAD2A in mitotic spindle checkpoint function and for survival of glioblastoma cells

Meeting Abstract

  • Almuth Keßler - Neurochirurgische Universitätsklinik, Tumorbiologisches Labor, Würzburg, Deutschland
  • Carsten Hagemann - Neurochirurgische Universitätsklinik, Tumorbiologisches Labor, Würzburg, Deutschland
  • Stefanie Gerngras - Neurochirurgische Universitätsklinik, Tumorbiologisches Labor, Würzburg, Deutschland
  • Rajnikant Patel - Department of Biochemistry, The Henry Wellcome Building, University of Leicester, United Kingdom
  • Ralf-Ingo Ernestus - Neurochirurgische Universitätsklinik, Tumorbiologisches Labor, Würzburg, Deutschland
  • Giles Hamilton Vince - Neurochirurgische Universitätsklinik, Tumorbiologisches Labor, Würzburg, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocV1539

DOI: 10.3205/10dgnc016, URN: urn:nbn:de:0183-10dgnc0160

Published: September 16, 2010

© 2010 Keßler et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

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Objective: MAD2A is a key regulator of the mitotic spindle checkpoint, which controls fidelity of spindle fiber attachment to sister chromatides. Defects in this checkpoint may contribute to chromosomal instability and may be involved in tumorigenesis. Since human malignant gliomas are highly aneuploid, we examined whether there are alterations in MAD2A expression and investigated how such alterations influence checkpoint function and proliferation rates of glioblastoma (GBM) cells.

Methods: Expression of MAD2A was determined by semiquantitative RT-PCR and Western-blotting, respectively, in a panel of 15 astrocytoma WHO II, 15 glioblastoma WHO IV and 3 normal brain biopsies and in an array of GBM cell lines. U251 and U373 GBM cells were transfected either with an MAD2A expression construct for protein overexpression or with specific siRNA for protein knock-down. Spindle checkpoint function was analysed by FACS analysis in presence or absence of the microtubuli damaging agent Nocodazole. Cell-survival and proliferation rates were monitored in real time for several days using the xCELLigence system (Roche).

Results: MAD2A expression was very diverse in glioma tissue samples from different patients, ranging from no detectable protein to very high expression levels. In comparison to untreated cells MAD2A depleted cells showed broadened peaks in FACS analysis. After Nocodazole treatment, which normally induces the mitotic checkpoint, no cell cycle arrest in G2/M phase could be observed and peaks were flattened and less confined compared to control cells. These results were confirmed by real time proliferation measurements. Untreated and MAD2A overexpressing cells arrested after Nocodazole treatment, knock-down cells continued to proliferate. However, MAD2A overexpression led to reduced proliferation rates (Control: 0.026 cycles/h, Overexpression: 0.019 cycles/h).

Conclusions: MAD2A is a key regulator of the mitotic spindle checkpoint in GBM cells. Recently, it has been shown that MAD2A-induced chromosome instability participates in lung tumor recurrence. Therefore, its loss in some GBM tissues could be of disadvantage for the patient, since the mitotic checkpoint is switched off. MAD2A overexpression reduces cell proliferation and may not only be a prognostic marker, but normalization of its expression levels could also be a therapeutic strategy to stabilize the chromosomal content and to slow down tumor growth rates.