Identification of small molecule inhibitors targeting brain tumor stem cells Free

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Cancer stem cells have been isolated from a number of different tumor types, including brain tumors (Singh et al., 2003; 2004, Hemmati et al., 2003; Galli et al., 2004). These cells have the capacity to self-renew and, at least to some extent, undergo multilineage differentiation in a manner analogous to tissue-specific stem cells. Cancer stem cell, although a minority of the cells within a given tumor mass have the capacity to generate entirely new tumors in immunodeficient mice and are relatively resistant to traditional therapies, such as radiation (Bao et al., 2006). Therefore, it is important to develop therapeutic strategies that directly target these cancer stem cells. In this study, we seek to use high throughput screening methods (HTS) to discover compounds that inhibit the survival or growth of putative brain tumor stem cells in glioblastoma multiforme (GBM). To develop an appropriate assay, we cultured a patient-derived GBM cell line in bFGF and EGF as previously described (Hemmati et al., 2003). ATP-Lite was used as a general measure of cell density and the assay was optimized using varying cell density. For the HTS, we plated 2500 cells into 384 well plates in the presence of more than 30,000 compounds (1 compound per well) derived from the ChemBridge Diver Set. From this screen, we uncovered 1000 compounds with inhibition of more than 95 percent. We then re-screened initial compounds and performed additional experiments to determine the effects of the compounds on normal human neural progenitors and a variety of cell lines derived from neural and non-neural cancers, as well as astrocytes and fibroblasts. 30 compounds were considered to be high priority candidates: i.e. those that demonstrated efficacy against putative GBM stem cells, without inducing global cell death in all the other lines. These compounds will serve as lead candidates for therapeutic development.References:

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