Identification and Characterization of Cancer Stem Cells in Mouse Medulloblastoma and Glioma

According to the cancer stem cell hypothesis a subpopulation of cells within a tumour has the capacity to sustain its growth. These cells are termed cancer stem cells, and are most simply defined as the cells within a primary tumour that can self-renew, differentiate and regenerate a phenocopy of that cancer when transplanted in vivo. Cancer stem cells have now been prospectively identified from numerous human tumours and are actively sought in many cancer types, both clinical and experimental. The cancer stem cell hypothesis remains controversial, with evidence both supporting and challenging its existence in human tumours and in animal models of disease. Here we prospectively identify and study brain cancer stem cells in clinically representative mouse models of the medulloblastoma and glioma. Cancer stem cells from both mouse brain tumour types are prospectively enriched by fluorescent activated cell sorting freshly dissociated cells for the surface antigen CD15, display a neural precursor phenotype, exhibit the hallmark stem cell characteristics of self-renewal and multilineage differentiation, and regenerate a phenocopy of the original tumour after orthotopic transplantation. Additionally, novel mouse medulloblastoma and glioma cancer stem cell lines were established and studied in vitro as adherent cultures in the same serum-free media conditions that support the growth of normal neural stem cells. When mouse and human glioma stem cell lines were compared, many novel molecular mediators of the tumour phenotype were identified, as were chemical compounds that selectively inhibit their growth. Our results have important implications regarding the cancer stem cell hypothesis, the mechanisms that drive brain tumour stem cell growth and the therapeutic strategies that may prove effective for the treatment of glioma and medulloblastoma.Ph