Abstract 666: Synthesis and structure-activity relationships of compounds that induce methuosis, a novel type of non-apoptotic cell death

Abstract

Abstract Methuosis is a caspase-independent form of necrotic cell death in which massive accumulation of vacuoles derived from macropinosomes ultimately causes cells to detach from the substratum and rupture. This form of death was initially described in glioblastoma cells overexpressing activated GTPases, such as Ras or Rac1, but methuosis-like forms of death have since been reported in other types of cells exposed to different stimuli. We have been interested in developing small molecules that can induce methuosis because of the possibility that stimulating this alternative death pathway may represent a useful therapeutic strategy for cancers that are refractory to apoptosis. We now describe the synthesis and biological testing of a class of small molecules that can effectively induce methuosis in glioblastoma cells at low micromolar concentrations. Details of the design and synthesis of a directed library of these novel compounds will be presented, including complete chemical structures and definition of structure-activity relationships. Each compound was evaluated for its ability to induce cytoplasmic vacuolization and reduce cell viability in U251 glioblastoma cells, using phase contrast microscopy, MTT and colony-forming assays as readouts. The results highlight a lead compound with an EC50 of approximately 1-3 micromolar, based on results from both MTT and colony-forming assays. Although the specific molecular target of these compounds is currently unknown, preliminary evidence indicates that they work at the level of endosome trafficking steps mediated by the Rab5 and Rab7 GTPases. The status of work toward target identification will be discussed. The potential significance of these studies is underscored by our recent observation that this class of compounds can induce methuosis in glioblastoma cells resistant to the front-line chemotherapeutic drug, temozolomide. This raises the possibility that the current lead compound may serve as a prototype for development of agents that could be used to trigger death by methuosis in drug-resistant cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 666. doi:10.1158/1538-7445.AM2011-666