Growth inhibition of cultured human glioma cells by beta-interferon is not dependent on changes in ganglioside composition

This investigation tested the hypothesis that the growth inhibiting effects of human ß-interferon on cultured human glioma cells involves changes in the ganglioside composition of these cells. Four cell lines derived from human malignant gliomas (12-18, U-251 MG, I29-A, 7-24) and two lines from human fetal brain (CHI, CHII) were cultured in the presence and in the absence of human ß-interferon (HuIFN- ß), 1,000 units per ml medium for three days before harvesting. Human ß-interferon had an inhibitory effect on growth of glioma but not fetal brain cells. Total ganglioside sialic acid for all cell lines ranged between 3.5 and 13.8 μg/10⁷ cells (0.6-3.9 μg/mg protein). No distinct difference in the amount of total ganglioside per cell was observed between neoplastic and non-neoplastic cells, but the latter had more ganglioside per mg total protein. All cell lines displayed different patterns ofgangliosides determined by high performance thin layer chromatography, but there was no distinct difference between glioma and fetal brain cells. Human ß-interferon increased the total amount of ganglioside per cell in one fetal brain and two glioma lines, but on a protein basis in only one glioma cell line (I29-A); HuIFN-ß had only minor effects on ganglioside patterns. There was a slight shift towards a greater proportion of structurally simpler gangliosides in both fetal brain and two glioma cell lines exposed to HuIFN-ß, but the reverse occurred in glioma U-251 MG. None of these changes strongly correlated with the degree of growth inhibition due to HuIFN-ß. Therefore, we conclude that HuIFN-ß can affect the ganglioside composition of some cultured fetal brain and glioma cells, but the biochemical mechanisms leading to the arrest of growth of glioma cells by HuIFN-ß are not absolutely dependent upon major changes in either the total amounts or patterns of gangliosides.