Extracellular matrix proteins control the growth of cerebellar medulloblastoma cells

Extracellular matrix proteins had been found to be involved in the embryonic development of the cerebellar cortex. Laminin is expressed in the outer most part of the external granular layer (EGL) and stimulates proliferation of neuronal precursors. In contrast, vitronectin is expressed in differentiated granule cells in deeper parts of the EGL. Investigation of cerebellar medulloblastomas showed that laminin is strongly expressed in vivo and increases proliferation and migration of tumour cells in vitro. In contrast, vitronectin is able to inhibit proliferation of DAOY cells deriving from a desmoplastic medulloblastoma. However, its expression and the vitronectin mediated phosphorylation of cyclic-AMP responsive element binding protein (CREB) which is responsible for granule cell differentiation seems to be lost in medulloblastomas. Further experiment showed that specific blockage of integrin receptors is able to abrogate the effects of extracellular matrix proteins and might provide a new approach to treat medulloblastomas.