flunarizine and Glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive brain tumor with a poor prognosis. The current treatment regimen, including surgical resection, radiation, and temozolomide (TMZ) chemotherapy, is still not curative. Therefore, there is an emerging need to develop a drug to treat GBM or synergistic enhance TMZ effect on GBM cells. Flunarizine (FLN), a drug approved for treating migraine and vertigo, was analyzed for its cytotoxicity and synergistic effect with TMZ on GBM cells in this study. Cell proliferation, clonogenic assay, flow cytometry, and Western blotting were used to determine the effects of FLN on three GBM cells, U-87 MG, LN-229, and U-118 MG cells. We found that FLN induced GBM cell death. FLN also interfered with U-87 MG cell cycle progression. Flow cytometric analysis showed an increase of apoptotic cells after FLN treatment. Caspase 9, caspase 3, and Poly (ADP-ribose) polymerase (PARP) activation were involved in apoptosis induction in U-87 MG and LN-229, suggesting the possible involvement of an intrinsic apoptotic pathway. We found that FLN treatment inhibited Akt pathway activation in U-87 MG cells, and synergistically increased the cytotoxicity of three GBM cells when combined with TMZ treatment. In conclusion, our current data suggested that FLN inhibited cell viability by inducing apoptosis. FLN inhibited Akt activation and enhanced the sensitivity of GBM cells to TMZ. These findings may provide important information regarding the application of FLN in GBM treatment in the future.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Brain Neoplasms; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Flunarizine; Glioblastoma; Humans; Proto-Oncogene Proteins c-akt; Signal Transduction; Temozolomide

Autophagy is a lysosome-dependent cellular catabolic mechanism mediating the turnover of intracellular organelles and long-lived proteins. Reduction of autophagy activity has been shown to lead to the accumulation of misfolded proteins in neurons and may be involved in chronic neurodegenerative diseases such as Huntington's disease and Alzheimer's disease. To explore the mechanism of autophagy and identify small molecules that can activate it, we developed a series of high-throughput image-based screens for small-molecule regulators of autophagy. This series of screens allowed us to distinguish compounds that can truly induce autophagic degradation from those that induce the accumulation of autophagosomes as a result of causing cellular damage or blocking downstream lysosomal functions. Our analyses led to the identification of eight compounds that can induce autophagy and promote long-lived protein degradation. Interestingly, seven of eight compounds are FDA-approved drugs for treatment of human diseases. Furthermore, we show that these compounds can reduce the levels of expanded polyglutamine repeats in cultured cells. Our studies suggest the possibility that some of these drugs may be useful for the treatment of Huntington's and other human diseases associated with the accumulation of misfolded proteins.

Topics: Autophagy; Calcium Channel Blockers; Cell Line, Tumor; Drug Evaluation, Preclinical; Fluspirilene; Glioblastoma; Green Fluorescent Proteins; Humans; Intracellular Membranes; Loperamide; Microtubule-Associated Proteins; Mycotoxins; Peptides; Phagosomes; Phosphatidylinositol Phosphates; Pimozide; Protein Kinases; Recombinant Fusion Proteins; Sirolimus; Small Molecule Libraries; TOR Serine-Threonine Kinases; Trifluoperazine; Zinc Fingers