PLASTIC PHENOTYPE OF HUMAN OLIGODENDROGLIAL TUMOR-CELLS IN-VITRO

Human oligodendroglioma cells cultured in serum-supplemented media los e their oligodendrocytic antigenic markers and acquire astrocytic mark ers. However, after reimplantation in rodent brain, these cells re-exp ress oligodendrocytic markers. This switch in human oligodendroglioma cell phenotype could result from the interplay of different stimuli in vitro vs in vivo, The ii vitro differentiation into astrocytes might result from non-physiological culture conditions. It is shown that hum an oligodendroglioma cells behave in a way similar to that of rodent b ipotential 0-2 A progenitor cells which can be driven to differentiate into either oligodendrocytes or type 2-astrocytes depending on the cu lture medium. Indeed, in serum-supplemented medium, human oligodendrog lioma cells proliferated and expressed the GFAP astrocytic marker. In chemically defined medium containing insulin, human oligodendroglioma cells were quiescent and expressed the 01 oligodendrocyte-specific mar ker. In both media, human oligodendroglioma cells expressed the A2B5 m embrane marker as well as the SCIP transcription factor specific of 0- 2 A cells, further confirming their oligodendrocytic origin. Replaceme nt of insulin by platelet-derived growth factor (PDGF) and basic fibro blast growth factor (bFGF), known to maintain 0-2 A progenitors in a p roliferative state, stimulated DNA replication of human oligodendrogli oma cells cultured in chemically defined medium.