Abstract 3820: Reduced migration and enhanced killing of glioblastoma multiforme by mefloquine via alteration of sphingolipid levels

Abstract

Abstract Purpose: Glioblastoma multiforme (GBM) is one of the most aggressive and common brain tumors. Current therapy for GBM is limited to surgery, radiation therapy and chemotherapy using temozolomide (TMZ). However, the emergence of resistance to TMZ and the ability of malignant gliomas to migrate away from the primary tumor site often results in recurrence of the tumor and failure of the initial therapy. This dire scenario illustrates the urgent need to identify novel agents that will be effective in TMZ-resistant tumors. In this study, we investigated the anticancer potential of an FDA approved antimalarial drug, mefloquine (MQ), in the in vitro model of GBM. MQ's impact on glioma viability, proliferation and migration was studied in a number of wild type and TMZ-resistant cells lines. We also evaluated the effects of MQ on intracellular levels of sphingolipids, which are bioactive lipids and have been recognized as the mediators of cellular proliferation and invasion in GBM. Method: To study the effect of MQ on TMZ resistance in vitro, we generated TMZ-resistant cell lines from established GBM cells. We evaluated the effects of MQ on cellular viability and proliferation by MTT assay and colony formation assay. Moreover, cell death was determined by analyzing the effect of MQ on various markers of apoptosis (e.g. cleavage of caspase 7 and PARP) using western blot. The effect of MQ on the migration of both TMZ-sensitive and -resistant cells was evaluated using wound healing scratch assay and Boyden chamber. To evaluate the impact of MQ on sphingolipids, we employed a validated LC-MS lipidomic assay to quantify the levels of various sphingolipids. Results: MQ was able to reduce cellular viability and proliferation in both TMZ-sensitive and -resistant GBM cells. MQ exerted its antitumor activity through induction of apoptosis. Our results further demonstrate the ability of MQ to reduce the migration of both TMZ-sensitive and -resistant GBM cell lines. In addition MQ was able to reduce the intracellular levels of sphingosine-1-phosphate (S1P), a pro-survival and pro-migratory sphingolipid and increased the levels of ceramide, a pro-apoptotic sphingolipid. Conclusion: Altogether our results demonstrate the ability of MQ to reduce cellular viability and proliferation and to induce apoptotic cell death in both TMZ-sensitive and -resistant GBM cells. It is conceivable that MQ exerts these effects by altering sphingolipid metabolism. These preliminary data suggests that MQ should be further investigated for cancer therapeutic purposes for TMZ-resistant GBM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3820. doi:1538-7445.AM2012-3820