IN-VITRO PROPERTIES OF A NEWLY ESTABLISHED MEDULLOBLASTOMA CELL-LINE,MCD-1

Medulloblastomas are poorly differentiated brain tumors believed to ar ise from primitive pleuripotential stem cells, and tend to express mix ed neuronal and glial properties. In the present study, we examined im munohistochemical and neurotransmitter phenotypic properties in a newl y established medulloblastoma cell line, MCD-1. MCD-1 cells were immor tal, not contact-inhibited, but did not grow in soft agar. Immunohisto chemical studies showed positive staining for neurofilament protein (N F), neuron-specific enolase (NSE), synaptophysin, MAP 2, tau, NCAM 180 , vimentin, and S-100 protein. The cells expressed specific uptake of glutamate, serotonin, and choline, but not GABA or dopamine. A signifi cant increase in process extension was seen in response to agents that enhance intracellular cyclic AMP, especially 3-isobutyl-1-methylxanth ine (IBMX). Process formation induced by IBMX was associated with a de crease in cell proliferation as evidenced by a reduction in numbers of cells incorporating 5-bromo-2-deoxyuridine (BrdU). No increase in pro cess extension was observed following exposure to NGF or retinoic acid . MCD-1 cells were shown to produce transforming growth factor beta (T GF beta), and were immunopositive for mutant p53. Transfection assays with the PG13-Luc reporter plasmid, which contains a p53-responsive en hancer element and a luciferase reporter gene, suggested MCD-1 cells a re deficient in wild-type p53 and do not activate p53 on treatment wit h the anticancer agent adriamycin. The MCD-1 cell line is suggested to represent an abnormally differentiated cell type, which has some prop erties consistent with a multipotent neuronal phenotype while retainin g some properties of immature cells of a glial lineage. The MCD-1 cell line can be used to provide a model of a medulloblastoma cell line th at is resistant to growth-controlling and anticancer agents.