CELL-GROWTH SUPPRESSION OF ASTROCYTOMA C6 CELLS BY GLIAL FIBRILLARY ACIDIC PROTEIN CDNA TRANSFECTION

The cellular functions of the intermediate filament family including g lial fibrillary acidic protein (GFAP) are not well known yet beyond th eir roles as structural elements of cells. Expression of GFAP, which i s specific in astrocytes and regulated developmentally, suggests its i nvolvement in cell growth and differentiation of astrocytes. We transf ected murine GFAP cDNA into a rat astrocytoma C6 cell line to assess t he specific effect of GFAP on cells. Two stable GFAP-transfected cell lines, GFC6-5 and GFC6-6, exhibited a series of morphological and grow th characteristics that distinguish them from their counterparts, i.e. , NeoC6 cells transfected only with the neomycin-resistant gene, and n ative C6 cells. Both GFC6-5 and GFC6-6 cells showed elongated cell sha pes with extended processes rich in GFAP, markedly suppressed cell gro wth, and decreased bromodeoxyuridine uptake. Western blot analysis rev ealed a remarkable increase of GFAP expression in GFC6-5 and GFC6-6 co mpared with that in NeoC6 and C6, in contrast to similar vimentin expr ession in all cell lines. The results indicate that the expression of GFAP has dramatic effects on cell morphology and cell growth suppressi on in C6 cells, suggesting that GFAP may function as a tumor suppresso r in astrocytoma.