Date Published: February 4, 2019
Publisher: Public Library of Science
Author(s): Falko Lange, Konrad Weßlau, Katrin Porath, Julia Hörnschemeyer, Carina Bergner, Bernd Joachim Krause, Christina Susanne Mullins, Michael Linnebacher, Rüdiger Köhling, Timo Kirschstein, Seok-Geun Lee.
Epileptic seizures are frequent in patients with glioblastoma, and anticonvulsive treatment is often necessary. While clinical guidelines recommend all approved anticonvulsants, so far it is still unclear which of the available drugs is the best therapeutic option for treating glioma-associated seizures, also in view of possible anti-tumorigenic effects. In our study, we employed four patient-derived low-passage cell lines of glioblastoma and three cell lines of brain metastases, and challenged these cultures with four anticonvulsants with different mechanisms of action: levetiracetam, valproic acid, carbamazepine and perampanel. Cell proliferation was determined by bromodeoxyuridine incorporation. To further analyze the effects of perampanel, apoptosis induction was measured by caspase 3/7 activation. Glutamate release was quantified and glucose uptake was determined using 18F-fluorodeoxyglucose. Real-time polymerase chain reaction was employed to assess the expression of genes associated with glutamate release and uptake in brain tumor cells. Of the four anticonvulsants, only perampanel showed systematic inhibitory effects on cell proliferation, whereas all other anticonvulsants failed to inhibit glioma and metastasis cell growth in vitro. Metastasis cells were much more resistant to perampanel than glioblastoma cell lines. Glucose uptake was attenuated in all glioblastoma cells after perampanel exposure, whereas cell death via apoptosis was not induced. Extracellular glutamate levels were found to be significantly higher in glioblastoma cell lines as compared to metastasis cell lines, but could be reduced by perampanel exposure. Incubation with perampanel up-regulated glutamine synthetase expression in glioblastoma cells, whereas treatment with valproic acid and levetiracetam downregulated excitatory amino acid transporter-2 expression. Overall, our data suggest that perampanel acts as an anticonvulsive drug and additionally mediated anti-tumorigenic effects.
Epileptic seizures are a common feature of primary brain tumors. In low-grade gliomas, up to 90% of the patients suffer from seizures, whereas in high-grade glioma (WHO grade III–IV) patients, at least 25–60% present with tumor-associated epilepsy [1–3]. Therefore, often not only an anti-tumorigenic treatment is necessary, but there is also a need for the control of epileptic seizures. To treat seizures, a broad range of antiepileptic drugs (AED) with different mechanisms of action are available, with many of the drugs having multiple or unknown targets [4,5].
Adequate control of epileptic seizures in patients with gliomas contributes significantly to the quality of life, particularly in palliative conditions when tumor remission may no longer be achieved. Currently, it is still unclear which of the available AEDs approved for the treatment of brain-tumor associated seizures could be the most beneficial drug with respect to both an anti-convulsive and anti-tumorigenic therapy. Undoubtedly, identification of an AED that beyond seizure control may also attenuate tumor progression would be of great clinical interest. To address this question, we took advantage of patient-derived low-passage cell lines of glioblastoma and brain metastasis samples. As shown for brain tumor and other cancer diseases, those in vitro models present a feasible tool close to the in vivo conditions to study drug effects in preclinical and translational research [36–38].