Stem cells are likely to play a central role in cancer. Their long lifespan and extensive capacity for self-renewal make them particularly sensitive to transformation, so they may represent a cell of origin for many tumors. A number of recent studies have suggested that stem-like cells are present in human brain tumors, but the role of stem cells in brain tumor initiation has not been tested. Studies in our lab are aimed at examining the role of neural stem cells in the etiology of the cerebellar tumor medulloblastoma.

Recent studies from our lab (Lee et al., 2005) have identified a population of neural stem cells in the postnatal cerebellum. These cells express the stem cell marker CD133, can form self-renewing "neurospheres"in culture, and can be induced to differentiate into neurons, astrocytes and oligodendrocytes both in vitro and following transplantation into the cerebellum. Our current research is directed at understanding the role of these cells in normal cerebellar development, and exploring the possibility that they might represent the cell of origin for some types of medulloblastoma. For an example of our studies in this area, see Yang et al., 2008.