Tissue culture of human neurocytomas induces the expression of glial fibrilary acidic protein

Cell cultures were established from three human neurocytoma specimens (prim ary and recurrent). The phenotypic evolution was analyzed by immunocytology in different culture conditions in the presence and absence of serum inclu ding the addition of epidermal growth factor, rat caudate extract, retinoic acid, and N-acetyl cystein. The cells were grown on glass cover slides or an extracellular matrix (ECM) from bovine corneal endothelial cells. Immuno stainings were performed after overnight incubation and were repeated after 5 and 10 days of culture. The cultures were compared to an oligoastrocytom a also arising at the foramen of Monro and an ependymoma of the frontal lat eral ventricle, two tumors supposedly originating from the same tissue matr ix as the neurocytoma. After overnight incubation, 90% of the neurocytoma c ells were positive for A2B5 and synaptophysin. GFAP reactivity appeared in the periphery of cell processes in less than 1% of the cells. The staining patterns and morphology were nearly identical under the different culture c onditions. After 5 days, almost all cells were strongly positive for GFAP, while the number of cells remaining positive for synaptophysin and A2B5 was unchanged from the earlier time point. Again, there were no fundamental di fferences between the incubation conditions. At this point, cultures mainta ined on ECM were compared to their counterparts on untreated glass cover sl ides with identical staining results, although many fewer cells had attache d. An identical immuno-reactive pattern was found on day 10. In contrast to the neurocytoma cultures, there was an immediate strong GFAP signal in bot h the mixed glioma and the ependymoma. A2B5 was also positive, but synaptop hysin was absent. Because the neurocytoma specimens were synaptophysin posi tive but GFAP negative by immunohistochemistry, it is concluded that neuroc ytomas may represent a human neuronoglial precursor tumor that switches its phenotype in culture to astroglial differentiation despite very diverse cu lture conditions.