Article
Hypoxia-inducible carbonic anhydrase IX enhances invasion of glioma cells in vitro
Die Hypoxie-induzierbare Carboanhydrase IX steigert das Invasionsverhalten von Gliomzellen in-vitro.
Search Medline for
Authors
-
M.A. Proescholdt
- Neurochirurgische Universitätsklinik, Klinikum der Universität Regensburg
-
C. Mayer
- Neurochirurgische Universitätsklinik, Klinikum der Universität Regensburg
-
S. Huber
- Neurochirurgische Universitätsklinik, Klinikum der Universität Regensburg
-
E.-M. Störr
- Neurochirurgische Universitätsklinik, Klinikum der Universität Regensburg
-
E. Stanbridge
- Department of Microbiology and Molecular Genetics, College of Medicine, University of California at Irvine, Irvine, California, USA
-
A. Brawanski
- Neurochirurgische Universitätsklinik, Klinikum der Universität Regensburg
| Published: | May 8, 2006 |
|---|
Outline
Text
Objective: Malignant gliomas display high glucose utilization rates and show increased lactate levels. Despite that, the intracellular pH is alkaline, whereas the extracellular pH is highly acidic. The membrane associated, hypoxia-inducible carbonic anhydrase (CA) IX may be involved in the maintenance of this intra – extracellular pH gradient. We hypothesized that CA IX may acidify the immediate extracellular milieu and create a microenvironment conductive to tumor invasion. We therefore induced CA IX expression by hypoxia in vitro and analyzed the invasive potential of the cells in the presence of a specific carbonic anhydrase inhibitor.
Methods: U251 glioblastoma cells were cultured in a Biocoat Matrigel invasion chamber purchased from Becton Dickinson. A matrigel - coated polycarbonate filter was situated between upper and the lower well plates The chambers were incubated in a humified 5% CO2 modular with either 0% or 21% oxygen for 6 and 12 hours. Expression of CA IX was demonstrated with Western blotting using antibodies specific for CA IX. Subsequently, cells were treated either with carrier or with acetazolamide at a concentration range between 40 nm and 40 mM. At the end of the incubation time, the cells that had penetrated the matrigel - coated filter were stained and counted visually. Percent invasion was corrected for proliferation and calculated accordingly.
Results: Western blot analysis confirmed a strong and long lasting induction of the CA IX protein expression. The invasion of glioma cells was significantly enhanced after hypoxic treatment (p=0.01). This invasive behavior was again strongly inhibited by the treatment with acetazolamide in a dose dependent fashion (p=0.002).
Conclusions: Our data suggest that CA IX may be functionally involved in glioma invasion by the acidification of the extracellular milieu and subsequent activation of proteases such as cathepsin B.
