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Molecular alterations in the neurofibromatosis type 2 gene and its protein rarely occurring in meningothelial

J J Evans1, S S Jeun, J H Lee

  • 1Department of Neurosurgery and the Center for Molecular Genetics, Cleveland Clinic Foundation, Ohio 44195, USA.

Journal of Neurosurgery
|January 9, 2001
PubMed
Abstract

Insights

Meningiomas rarely show NF2 gene mutations or reduced protein, suggesting other genes drive tumor growth in meningothelial types. This indicates NF2 gene-independent pathways are key in meningioma development.

Area of Science:

  • Oncology
  • Genetics
  • Neurosurgery

Background:

  • The neurofibromatosis Type 2 (NF2) gene is a known tumor suppressor implicated in benign meningioma development.
  • Reduced NF2 protein expression is uncommon in meningothelial meningiomas, the most frequent subtype.

Purpose of the Study:

  • To investigate the hypothesis that meningothelial meningiomas can develop independently of NF2 gene alterations.
  • To explore alternative molecular mechanisms driving meningothelial meningioma tumorigenesis.

Main Methods:

  • Mutational analysis of all 17 exons of the NF2 gene using single-stranded conformational polymorphism (SSCP).
  • Immunoblotting analysis to determine NF2 protein and mu-calpain expression levels in 27 meningiomas (20 meningothelial, 7 nonmeningothelial).

Main Results:

  • NF2 gene mutations were found in only 5% of meningothelial meningiomas versus 43% of nonmeningothelial tumors (p=0.042).
  • Severe reduction in NF2 protein levels occurred in 28.5% of meningothelial meningiomas, compared to 86% of nonmeningothelial meningiomas (p=0.023).
  • Mu-calpain activation did not correlate with NF2 protein levels, ruling it out as a cause for NF2 loss in NF2-normal meningiomas.

Conclusions:

  • NF2 gene mutations and decreased NF2 protein expression are rare in meningothelial meningiomas compared to other histological types.
  • The similar clinical behavior of meningothelial meningiomas to other benign meningiomas suggests alternative genetic pathways.
  • Tumorigenesis of meningothelial meningiomas likely involves alterations in other genes that phenotypically mimic NF2 gene inactivation.

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