Microarray analysis of differentiation of human glioblastoma stem cells

Glioblastoma multiforme is one of the most devastating cancers and presents unique challenges to therapy due to its aggressive behaviour. Cancer stem cells have been described to be the only cell population with tumorogenic capacity in glioblastoma. Therefore, effective therapeutic strategies targeting these cells may be beneficial. We have established different cultures of glioblastoma stem cells (GSCs) derived from surgical specimens and found that, after induction of differentiation, NFκB was activated, which allows intermediate tumor precursor cells to remain cycling. We also showed that blockade of NFκB signaling in differentiating GSCs by different genetic strategies or treatment with small molecule inhibitors, promoted replication arrest, progression to a mature phenotype, mainly neuronal cells, and senescence. This effect was partly mediated by downregulation of the NFκB target gene cyclin D1. Furthermore, intravenous treatment of immunodeficient mice bearing human GSC-derived tumors with a novel small-molecule inhibitor of the NFκB pathway induced senescence of tumor cells but no ultraestructural alterations of the brain parenchymal cells were detected. These findings reveal that activation of NFκB may keep differentiating GSCs from acquiring a mature postmitotic phenotype, thus allowing cell proliferation, and support the rationale for therapeutic strategies aimed at promoting premature senescence in GSCs undergoing differentiation. Gene expression in differentiated cells relative to stem cells in three different glioblastoma cultures