Ezrin-dependent promotion of glioma cell clonogenicity, motility, and invasion mediated by BCL-2 and transforming growth factor-beta2

J Neurosci. 2001 May 15;21(10):3360-8. doi: 10.1523/JNEUROSCI.21-10-03360.2001.

Abstract

Ezrin belongs to the ezrin-radixin-moesin family proteins, which cross-link actin cytoskeleton and plasma membrane. Malignant glioma cells are paradigmatic for their strong migratory and invasive properties. Here, we report that the expression of dominant-negative ezrins inhibits clonogenicity, migration, and invasiveness of human malignant glioma cells. Furthermore, dominant-negative ezrins block hepatocyte growth factor (HGF)-mediated stimulation of clonogenicity and migration, without altering HGF-induced protein kinase B/Akt and focal adhesion kinase phosphorylation. Glioma cells expressing dominant-negative ezrins exhibit a shift of the BCL-2/BAX rheostat toward apoptosis, reduced alpha(V)beta(3) integrin expression and reduced matrix metalloproteinase (MMP) expression and activity. These changes are associated with a dramatic loss of transforming growth factor beta(2) (TGF-beta(2)) release. Exogenous supplementation of TGF-beta(2) overcomes the inhibitory effects of dominant-negative ezrins on migration and clonogenicity. A neutralizing TGF-beta(2) antibody mimics the effects of dominant-negative ezrins on clonogenicity and migration. Exogenous HGF markedly induces TGF-beta(2) protein levels, and a neutralizing TGF-beta(2) antibody abolishes the HGF-mediated increase in glioma cell motility. Finally, TGF-beta(2) does not modulate BCL-2 or BAX expression, but BCL-2 gene transfer increases the levels of latent and active TGF-beta(2). Intracranial xenografts of U87MG glioma cells transfected with the dominant-negative ezrins in athymic mice grow to significantly smaller volumes, and the median survival of these mice is 50 d compared with 28 d in the control group. These data define a novel pathway for HGF-induced glioma cell migration and invasion, which requires ezrin, changes in the BCL-2/BAX rheostat, and the induction of TGF-beta(2) expression in vitro, and underscore the important role of HGF signaling in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Cell Division / drug effects
  • Cell Division / genetics
  • Cell Movement / drug effects
  • Cell Movement / genetics
  • Cytoskeletal Proteins
  • Disease Models, Animal
  • Genes, Dominant
  • Glioma / genetics
  • Glioma / metabolism*
  • Glioma / pathology
  • Hepatocyte Growth Factor / pharmacology
  • Humans
  • Mice
  • Mice, Nude
  • Neoplasm Invasiveness / genetics
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphoproteins / pharmacology
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Rats
  • Receptors, Vitronectin / metabolism
  • Survival Rate
  • Transfection
  • Transforming Growth Factor beta / metabolism*
  • Transforming Growth Factor beta / pharmacology
  • Transforming Growth Factor beta2
  • Tumor Cells, Cultured
  • Tumor Stem Cell Assay
  • Xenograft Model Antitumor Assays
  • bcl-2-Associated X Protein

Substances

  • BAX protein, human
  • Bax protein, mouse
  • Bax protein, rat
  • Cytoskeletal Proteins
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Receptors, Vitronectin
  • TGFB2 protein, human
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta2
  • bcl-2-Associated X Protein
  • ezrin
  • Hepatocyte Growth Factor