Ezrin-dependent promotion of glioma cell clonogenicity, motility, and invasion mediated by BCL-2 and transforming growth factor-beta2.
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.
Wick
W
W
Laboratory of Molecular Neuro-Oncology, Department of Neurology, University of Tübingen, School of Medicine, Tübingen, Germany. wolfgang.wick@uni-tuebingen.de
Grimmel
C
C
Wild-Bode
C
C
Platten
M
M
Arpin
M
M
Weller
M
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D003598:Cytoskeletal Proteins; D004195:Disease Models, Animal; D005799:Genes, Dominant; D005910:Glioma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness / Q000235:genetics; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D019030:Receptors, Vitronectin / Q000378:metabolism; D015996:Survival Rate; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology; D053781:Transforming Growth Factor beta2; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay; D023041:Xenograft Model Antitumor Assays; D051028:bcl-2-Associated X Protein; D000099149:Ezrin
D003598:Cytoskeletal Proteins; D017228:Hepatocyte Growth Factor; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D019030:Receptors, Vitronectin; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2; D051028:bcl-2-Associated X Protein; D000099149:Ezrin; C494826:BAX protein, human; C494827:Bax protein, mouse; C494828:Bax protein, rat; C509041:TGFB2 protein, human