Ganglioside composition of GH3 cells: enhancement of fucoganglioside expression by estradiol, epidermal growth factor and insulin.

The GH3 cell line, a bipotential cell line secreting both prolactin (PRL) and growth hormone (GH), is a useful model for investigating GH/PRL cell lineage differentiation and anterior pituitary adenoma formation. In this study, we investigated the ganglioside composition of GH3 cells and identified two fucogangliosides as the major gangliosides expressed by these cells. Analyses by DEAE-Sephadex A-25 and thin-layer chromatography (TLC) revealed that the GH3 cells contained two major gangliosides, designated FG1 and FG2, respectively. Their structures were identified by fast atom bombardment mass spectrometry and proton nuclear magnetic resonance spectrometry: FG1 is IV2FUc alpha,II3NeuAc-GgOse4Cer and FG2 is IV2FUc alpha,IV3Gal alpha,II3NeuAc-GgOse4Cer. Expression of these fucogangliosides was enhanced by chronic treatment with 17 beta-estradiol (1 nM), epidermal growth factor (10 nM) and insulin (300 nM), which induced differentiation of GH3 cells to normal PRL-secreting cells. Interestingly, immunocytochemistry and flow cytometry revealed that the increased expression of these gangliosides reflected a quantitative change inside the cells but not on the cell surface. These results suggest that the intracellular distribution of fucogangliosides is closely related to the differentiation of GH3 cells.