Article
Lab Invest 2000, 80:1681–1689
The Endothelin System in Human Glioblastoma
This work has been supported by the Swiss National Science Foundation (Grant 32.045908.95), the Swiss League and Research Against Cancer (Grant SKL 353-9-1996), the Swiss Society for Multiple Sclerosis, the Ministère des Affaires Etrangères, the Swiss Program "Cotutelle de thèse" and the French Embassy in Switzerland, the Foundation Cino and Simone del Duca, the Foundation pour la Recherche Médicale, and the Ministère Français de la Recherche et de l'Enseignement (ACC-SV9).
We would like to thank Ms. S. Gross, Ms. P. Fioroni, and Ms. R. Bovey for excellent technical assistance; Dr. M. Clozel, Actelion, Basel, Switzerland, for the gift of bosentan; and Drs. Jürg Tschopp, J. D. Aubert, and F. T. Bosman for very helpful discussion and suggestions.
Giorgia Egidy1, Lucie Peduto Eberl2, Olivier Valdenaire5, Martin Irmler4, Rachid Majdi2, Annie-Claire Diserens3, Adriano Fontana6, Robert-Charles Janzer2, Florence Pinet1 and Lucienne Juillerat-Jeanneret2
- 1INSERM U36, Collège de France, Paris, France
- 2Institute of Pathology, CHUV, Lausanne, Switzerland
- 3Division of Neurosurgery, CHUV, Lausanne, Switzerland
- 4Institute of Biochemistry, University of Lausanne, Lausanne, Switzerland
- 5Actelion Ltd, Basel, Switzerland
- 6Clinical Immunology, University Hospital, Zürich, Switzerland
Correspondence: Dr. L. Juillerat, Institute of Pathology, Bugnon 27, CH1011 Lausanne, Switzerland. Fax: 41 21 314 7175; E-mail: lucienne.juillerat@chuv.hospvd.ch
Received 21 June 2000.
Abstract
Endothelin-1 (ET-1) is a powerful mitogenic and/or anti-apoptotic peptide produced by many cancer cells. To evaluate the potential role of the endothelin system in glioblastoma we first determined the cellular distribution of the mRNA and proteins of the components of the endothelin system, preproendothelin-1 (PPET-1), endothelin-converting enzyme-1 (ECE-1), and ETA and ETB receptors in human glioblastoma tissue and glioblastoma cell lines. PPET-1, ECE-1, and ETA receptor were highly expressed in glioblastoma vessels and in some scattered glioblastoma areas whereas ETB receptor was mainly found in cancer cells. This suggests that glioblastoma vessels constitute an important source of ET-1 that acts on cancer cells via the ETB receptor. Four human glioblastoma cell lines expressed mRNA for all of the components of the ET-1 pathway. Bosentan, a mixed ETA and ETB receptor antagonist, induced apoptosis in these cell lines in a dose-dependent manner. Apoptosis was potentiated by Fas Ligand (APO-1L, CD95L), a pro-apoptotic peptide, only in LNZ308 cells, corresponding to the known functional Fas expression in these cell lines. LNZ308 cells also expressed the long and short forms of the cellular FLICE/caspase-8 inhibitory protein (FLIP). Bosentan and a protein kinase C inhibitor down-regulated short FLIP in these cells. ET-1 induced transient phosphorylation of extracellular signal-regulated kinase but did not induce long-term thymidine incorporation in LNZ308 glioblastoma cells. These results suggest that, in glioblastoma cells, ET-1, mainly acting via the ETB receptor, is a survival/anti-apoptotic factor produced by tumor vasculature, but not a proliferation factor, involving protein kinase C and extracellular signal-regulated kinase pathways, and stabilization of the short form of FLIP.
