Functional analysis of trk proto-oncogene product in medulloblastoma cells.

MED-L cells with the 75 kd low-affinity nerve growth factor receptor (p75NGFR) and MED-H cells with the proto-oncogene tropomyosin receptor kinase product (p140trk) were isolated selectively from a parent MED-3 cell line derived from cerebellar medulloblastoma by panning, and the interaction of nerve growth factor (NGF) with these cell lines was analyzed. NGF treatment induced neuronal differentiation, growth inhibition, and tyrosine phosphorylation of p140trk in MED-H cells, but not in MED-L cells. Medulloblastoma cells express the functional NGFR, p140trk, which regulates their differentiation and growth.