STEM-03
ATRACURIUM BESYLATE AND OTHER NEUROMUSCULAR BLOCKING AGENTS PROMOTE ASTROGLIAL DIFFERENTIATION AND DEPLETE GLIOBLASTOMA STEM CELLS Free

Glioblastoma multiforme (GBM) are the most common primary malignant brain tumor in adults, with a median survival of about one year. This poor prognosis is attributed primarily to therapeutic resistance and tumor recurrence after surgical removal, with the root cause suggested to be found in glioblastoma stem cells (GSCs). Using glial fibrillary acidic protein (GFAP) and microtubule associated protein-2 (MAP-2) as reporters of astrocytic and neuronal differentiation, respectably; we isolated multiple clones from three independent patient-derived GSC neurosphere lines which express GFAP or MAP2 in a remarkably stable fashion. We next show that elevated expression of GFAP is associated with reduced clonogenicity in vitro and tumorigenicity in vivo. Utilizing this in vitro cell-based differentiation reporter system we next screened the NIH clinical collection libraries for agents capable of inducing GSC astrocytic differentiation. We identified the non-depolarizing neuromuscular blocker, Atracurium Besylate, as a small molecule which effectively induces astroglial but not neuronal differentiation of GSC. Functionally, Atracurium Besylate treatment significantly inhibited the clonogenic capacity of several independent patient-derived GSC neurosphere lines, a phenomenon which was largely irreversible. Vecuronium, another non-depolarizing neuromuscular blocker, also induced GSC astrocytic differentiation suggesting that inhibition of acetylcholine receptors (AChRs) may be the mechanism responsible for GSC astrocytic differentiation. To investigate the clinical importance of AChRs in gliomas, we examined clinical outcomes and found that glioma patients with tumors overexpressing CHRNA1 or CHRNA9 (encoding for the AChR-α1 or AChR-α9 subunits) exhibit significant shorter overall survival. Finally, we found that ex-vivo pre-treatment of GSCs with Atracurium Besylate significantly increased the survival of mice xenotransplanted with these cells, therefore suggesting that tumor initiating subpopulations have been reduced.