Article
Inhibition efficacy of extracellular carbonic anhydrases in glioblastoma depends on the glycolytic phenotype
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Authors
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Martin A. Proescholdt
- Universitätsklinikum Regensburg, Klinik für Neurochirurgie, Regensburg, Deutschland
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Eva-Maria Stoerr
- Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg, Regensburg, Deutschland
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Annette Lohmeier
- Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg, Regensburg, Deutschland
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Alexander T. Brawanski
- Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg, Regensburg, Deutschland
| Published: | June 9, 2017 |
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Outline
Text
Objective: Malignant gliomas metabolize glucose preferably by glycolysis which is in accordance to the Warburg effect. This induces a high demand of glucose combined with a significant lactic acid load. Surprisingly, the intracellular pH has been demonstrated to be slightly alkaline in these tumors. The hypoxia – inducible, extracellular carbonic anhydrase IX (CAIX) is highly overexpressed in malignant gliomas and plays an important role in their acid management and cell survival. Recently, specific inhibitors of this enzyme have been developed and may provide an innovative strategy for adjuvant treatment. The goal of our study was to test several of these compounds for their efficacy in glioblastoma cells in vitro compared to normal astrocytes.
Methods: Two established rat and two established human glioblastoma (GBM) cell lines and 4 primary GBM cell lines (2 with mesenchymal transcriptional profile and 2 with proneural profile) were exposed to CAIX inhibitors in different concentrations. As control cells served normal rat astrocytes derived from p3 rat brains. Cell toxicity was measured by a colorimetric assay (AQ assay, Promega), apoptotic cell death was investigated by annexin V labeling. To investigate potential biomarker for treatment efficacy, a glycolytic profile of all cell lines was established by measuring lactate production, activity of glycolytic key enzymes, the extracellular acidification rate in addition to the oxygen consumption rate.
Results: Normal astrocytes did not show any toxic reaction to CAIX inhibition even at high dosages. In contrast, several GBM cell lines were highly susceptible to CAIX inhibition, whereas others were rather refractory. The glycolytic profiling revealed that a highly glycolytic phenotype correlates with profound efficacy of CAIX inhibition, whereas a lower glycolytic activity was associated with significantly reduced efficacy of this approach. Glycolytic enzyme activity was established as a reliable marker for the response rate of GBM cells to CAIX inhibition.
Conclusion: Our data demonstrate that CAIX inhibition can be an effective treatment strategy in GBM with a high glycolytic potential resulting in a significant acid load requiring the function of this enzyme complex.
