EFFECT OF GROWTH-FACTORS ON THE IN-VITRO GROWTH AND DIFFERENTIATION OF EARLY AND LATE PASSAGE C6 GLIOMA-CELLS

The effect of different hormones and growth factors was assayed on the in vitro growth and enzymatic activities of 2',3'-cyclic nucleotide 3 'phosphohydrolase (CNP) and glutamine synthetase (GS) of rat glioma C6 cells at two different passages in culture. Young cultures (passage 2 6), mainly oligodendrocytic, and older cultures (passage 134), predomi nantly astrocytic, were treated with 10 mu M dexamethasone, 20 ng/ml t ransforming growth factor alpha (TGF alpha), 10 ng/ml insulin, 20 ng/m l platelet-derived growth factor (PDGF), and 20 ng/ml, epidermal growt h factor (EGF) in serum-free chemically defined media. In vitro growth rate was measured in terms of DNA content, by a fluorometric method o f diamino-benzoic acid, and rate of DNA synthesis by H-3-thymidine inc orporation. CNP activity (marker for in vitro oligodendrocytes) and GS activity (marker for astrocytes) were determined spectrophotometrical ly. Dexamethasone reversibly and significantly inhibited growth of C6 glioma in early and late passages. PDGF and insulin promoted in vitro growth only in late passage but not in early passage cells, whereas EG F and TGF alpha did not significantly affect growth. An increase in CN P activity was observed in early passage cells under the effect of PDG F and insulin. The increase in GS activity induced by insulin and dexa methasone suggests a differentiating role for these factors in C6 glio ma cells. These results further present the C6 glioma cell line as a u seful model for studies on glial cell properties and responsiveness in culture and support its use in experimental aging in vitro. Copyright (C) 1996 ISDN.