GANGLIOSIDE COMPOSITION OF GH(3) CELLS - ENHANCEMENT OF FUCOGANGLIOSIDE EXPRESSION BY ESTRADIOL, EPIDERMAL GROWTH-FACTOR AND INSULIN

The GH(3) 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 format ion. In this study, we investigated the ganglioside composition of GH( 3) cells and identified two fucogangliosides as the major gangliosides expressed by these cells, Analyses by DEAE-Sephadex A-25 and thin-lay er chromatography (TLC) revealed that the GH(3) cells contained two ma jor gangliosides, designated FG1 and FG2, respectively. Their structur es were identified by fat atom bombardment mass spectrometry and proto n nuclear magnetic resonance spectrometry: FG1 is IV(2)Fuc alpha,II(3) NeuAc-GgOse(4)Cer and FG2 is IV2 Fuc alpha,IV(3)Gal alpha,II(3)NeuAc-G gOse(4)Cer. Expression of these fucogangliosides was enhanced by chron ic treatment with 17 beta-estradiol (1 nM), epidermal growth factor (1 0 nM) and insulin (300 nM), which induced differentiation of GH(3) cel ls to normal PRL-secreting cells, Interestingly, immunocytochemistry a nd flow cytometry revealed that the increased expression of these gang liosides reflected a quantitative change inside the cells but not on t he cell surface. These results suggest that the intracellular distribu tion of fucogangliosides is closely related to the differentiation of GH(3) cells. (C) 1998 Elsevier Science B.V.