Vacquinol-1 inducible cell death in glioblastoma multiforme is counter regulated by TRPM7 activity induced by exogenous ATP.

Glioblastomas (GBM) are the most malignant brain tumors in humans and have a very poor prognosis. New therapeutic options are urgently needed. A novel drug, Vacquinol-1 (Vac), a quinolone derivative, displays promising properties by inducing rapid cell death in GBM but not in non-transformed tissues. Features of this type of cell death are compatible with a process termed methuosis. Here we tested Vac on a highly malignant glioma cell line observed by long-term video microscopy. Human dental-pulp stem cells (DPSCs) served as controls. A major finding was that an exogenous ATP concentration of as little as 1 µM counter regulated the Vac-induced cell death. Studies using carvacrol, an inhibitor of transient receptor potential cation channel, subfamily M, member 7 (TRPM7), demonstrated that the ATP-inducible inhibitory effect is likely to be via TRPM7. Exogenous ATP is of relevance in GBM with large necrotic areas. Our results support the use of GBM cultures with different grades of malignancy to address their sensitivity to methuosis. The video-microscopy approach presented here allows decoding of signaling pathways as well as mechanisms of chemotherapeutic resistance by long-term observation. Before implementing Vac as a novel therapeutic drug in GBM, cells from each individual patient need to be assessed for their ATP sensitivity. In summary, the current investigation supports the concept of methuosis, described as non-apoptotic cell death and a promising approach for GBM treatment. Tissue-resident ATP/necrosis may interfere with this cell-death pathway but can be overcome by a natural compound, carvacrol that even penetrates the blood-brain barrier.

Immune phenotypes predict survival in patients with glioblastoma multiforme.

BACKGROUND: Glioblastoma multiforme (GBM), a common primary malignant brain tumor, rarely disseminates beyond the central nervous system and has a very bad prognosis. The current study aimed at the analysis of immunological control in individual patients with GBM. METHODS: Immune phenotypes and plasma biomarkers of GBM patients were determined at the time of diagnosis using flow cytometry and ELISA, respectively. RESULTS: Using descriptive statistics, we found that immune anomalies were distinct in individual patients. Defined marker profiles proved highly relevant for survival. A remarkable relation between activated NK cells and improved survival in GBM patients was in contrast to increased CD39 and IL-10 in patients with a detrimental course and very short survival. Recursive partitioning analysis (RPA) and Cox proportional hazards models substantiated the relevance of absolute numbers of CD8 cells and low numbers of CD39 cells for better survival. CONCLUSIONS: Defined alterations of the immune system may guide the course of disease in patients with GBM and may be prognostically valuable for longitudinal studies or can be applied for immune intervention.

Artesunate enhances the antiproliferative effect of temozolomide on U87MG and A172 glioblastoma cell lines.

As chemotherapy with temozolomide is far from providing satisfactory clinical outcomes for patients with glioblastoma, more efficient drugs and drug combinations are urgently needed. The anti-malarial artesunate was previously shown to exert a profound cytotoxic effect on various tumor cell lines including those derived from glioblastoma. In the current study, we sought to examine the antiproliferative effect of a combination of temozolomide and artesunate on two different established human glioblastoma cell lines. The IC50 and IC25 were determined for temozolomide and artesunate in U87MG and A172 glioblastoma cell lines after 144 h of continuous drug exposure. The antiproliferative effect of combining both agents at IC50/IC50 and IC25/IC25 was determined by a cell viability assay. Moreover, necrosis and apoptosis were analyzed by annexin V/PI staining and flow cytometric analysis. In addition, cytostatic effects were examined by carboxyfluorescein diacetate succinimidyl ester staining and subsequent flow cytometry. In both glioblastoma cell lines, artesunate was found to enhance the antiproliferative effect exerted by temozolomide. Moreover, artesunate acted in concert with temozolomide in terms of cytostatic and necrotizing effects. These observations suggest that a combination of artesunate and temozolomide might result in increased cytotoxicity in glioblastoma.