An embryonic origin for medulloblastoma.

Medulloblastoma is a common brain tumor of children. Three differentiated cell types are found in medulloblastomas: neurons, glia, and muscle cells. Because of the presence of multiple differentiated cell types these tumors were named after a postulated cerebellar stem cell, the medulloblast, that would give rise to the differentiated cells found in the tumors. We describe a cell line with the properties expected of the postulated medulloblast. The rat cerebellar cell line ST15A expresses an intermediate filament, nestin, that is characteristic of neuroepithelial stem cells. ST15A cells can differentiate, gaining either neuronal or glial properties. In this paper we show that the same clonal cell can also differentiate into muscle cells. This result suggests that a single neuroectodermal cell can give rise to the different cell types found in medulloblastoma. We also show expression of nestin in human medulloblastoma tissue and in a medulloblastoma-derived cell line. Both the properties of the ST15A cell line and the expression of nestin in medulloblastoma support a neuroectodermal stem cell origin for this childhood tumor.