Fluvoxamine, an anti-depressant, inhibits human glioblastoma invasion by disrupting actin polymerization

Scientific Reports, Mar 2016

Glioblastoma multiforme (GBM) is the most common malignant brain tumor with a median survival time about one year. Invasion of GBM cells into normal brain is the major cause of poor prognosis and requires dynamic reorganization of the actin cytoskeleton, which includes lamellipodial protrusions, focal adhesions, and stress fibers at the leading edge of GBM. Therefore, we hypothesized that inhibitors of actin polymerization can suppress GBM migration and invasion. First, we adopted a drug repositioning system for screening with a pyrene-actin-based actin polymerization assay and identified fluvoxamine, a clinically used antidepressant. Fluvoxamine, selective serotonin reuptake inhibitor, was a potent inhibitor of actin polymerization and confirmed as drug penetration through the blood–brain barrier (BBB) and accumulation of whole brain including brain tumor with no drug toxicity. Fluvoxamine inhibited serum-induced ruffle formation, cell migration, and invasion of human GBM and glioma stem cells in vitro by suppressing both FAK and Akt/mammalian target of rapamycin signaling. Daily treatment of athymic mice bearing human glioma-initiating cells with fluvoxamine blocked tumor cell invasion and prolonged the survival with almost same dose of anti-depressant effect. In conclusion, fluvoxamine is a promising anti-invasive treatment against GBM with reliable approach.

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Fluvoxamine, an anti-depressant, inhibits human glioblastoma invasion by disrupting actin polymerization

Abstract Glioblastoma multiforme (GBM) is the most common malignant brain tumor with a median survival time about one year. Invasion of GBM cells into normal brain is the major cause of poor prognosis and requires dynamic reorganization of the actin cytoskeleton, which includes lamellipodial protrusions, focal adhesions, and stress fibers at the leading edge of GBM. Therefore, we hypothesized that inhibitors of actin polymerization can suppress GBM migration and invasion. First, we adopted a drug repositioning system for screening with a pyrene-actin-based actin polymerization assay and identified fluvoxamine, a clinically used antidepressant. Fluvoxamine, selective serotonin reuptake inhibitor, was a potent inhibitor of actin polymerization and confirmed as drug penetration through the blood–brain barrier (BBB) and accumulation of whole brain including brain tumor with no drug toxicity. Fluvoxamine inhibited serum-induced ruffle formation, cell migration, and invasion of human GBM and glioma stem cells in vitro by suppressing both FAK and Akt/mammalian target of rapamycin signaling. Daily treatment of athymic mice bearing human glioma-initiating cells with fluvoxamine blocked tumor cell invasion and prolonged the survival with almost same dose of anti-depressant effect. In conclusion, fluvoxamine is a promising anti-invasive treatment against GBM with reliable approach. Introduction Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor, with a median survival of approximately 1 year. Despite advances in diagnostics and treatment, the prognosis for GBM has not significantly improved in recent decades1. This poor prognosis is mainly due to the highly invasive nature of GBM cells. Diffused GBM cell invasion into surrounding normal brain tissue prevents complete surgical resection of GBM tumors and results in recurrence. Furthermore, in the central nervous system, most anti-cancer drugs, including molecular-targeted drugs, forming a first line of treatment against various cancers are ineffective because the BBB prevents their delivery into the brain2. Therefore, the development of novel anti-invasive drugs that can permeate the BBB is essential for treatment of GBM. Recent studies have identified CD133+ glioma-initiating cells (GICs) that exhibit stem cell-like properties3,4.These GICs possess capacities for tumorigenesis, self-renewal, and differentiation into multiple cell types, such as neurons, astrocytes, and oligodendrocytes4,5. GICs have been shown to be highly invasive and resistant to chemotherapy and radiotherapy6,7,8. Therefore, GICs are thought to be responsible for the poor prognosis of GBM and constitute a potential target for GBM therapy. Tumor cell migration and invasion require dynamic reorganization of the actin cytoskeleton9,10. Migrating cells produce membrane protrusions, such as filopodia, lamellipodia, invadopodia, focal adhesions, and stress fibers11. Because these structures of migrating cells require precise regulation of actin polymerization and depolymerization, control of actin polymerization in tumor cells on the leading edge of the tumor may inhibit invasion and migration of GBM cells into normal brain. In terms of drug development and clinical applications, the cost of development and unexpected side effects just before clinical use obstruct the process from basic research to clinical use. As a result, finding new uses for existing clinically used drugs, termed drug repositioning or repurposing, is an alternative strategy for drug discovery and development12. This approach has been widely attempted and has been successful in some cases (e.g., aspirin as an anti-platelet medication, sildenafil for erectile dysfunction, etc.)12,13. Because the pharmacokinetics of most existing clinically used drugs have already been studied, the effective dose, possible side effects, cost are already known and the time required to bring these drugs to market can be reduced14. Results Fluvoxamine found to inhibit actin polymerization using a new screening method for quantitative determination of actin polymerization Reorganization of the actin cytoskeleton is essential for cancer cell migration and invasion. Therefore, we established a new drug screening method for in vitro quantitative determination of actin polymerization and screened clinically used drugs that can penetrate the BBB. To test the new screening method, we first screened inhibitors of actin polymerization from among 18 clinically used drugs that can permeate the BBB (Table 1) using a pyrene-actin-based actin polymerization assay. This assay is based on enhancement of the fluorescence of pyrene-labeled G-actin (monomer) that occurs during polymerization (Fig. 1a–c). Each drug was added to the reaction mixture at a concentration of 40 μM, and the fluorescence of pyrene-actin was measured. We found that drug No. 16, the antidepressant fluvoxamine, exhibited the most potent inhibition against actin (...truncated)


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Keiichiro Hayashi, Hiroyuki Michiue, Hiroshi Yamada, Katsuyoshi Takata, Hiroki Nakayama, Fan-Yan Wei, Atsushi Fujimura, Hiroshi Tazawa, Akira Asai, Naohisa Ogo, Hiroyuki Miyachi, Tei-ichi Nishiki, Kazuhito Tomizawa, Kohji Takei, Hideki Matsui. Fluvoxamine, an anti-depressant, inhibits human glioblastoma invasion by disrupting actin polymerization, Scientific Reports, 2016, Issue: 6, DOI: 10.1038/srep23372