Glycolipid Core Structure Switching from Globo- to Lacto- and Ganglio-series During Retinoic Acid-induced Differentiation of TERA-2-derived Human Embryonal Carcinoma Cells

We have analyzed the glycolipid markers of a recently cloned human embryonal carcinoma (EC) cell line, NTERA-2, which differentiates extensively into a variety of somatic cell types when exposed to retinoic acid. These tumor cells provide a model system that can be used to study the ontogeny of glycolipid diversity during human embryonic development. Glycolipid antigens were identified by cell surface immunofluorescence and thin-layer chromatography immunostaining using a comprehensive set of anticarbohydrate monoclonal antibodies. Undifferentiated NTERA-2 cells were found to express predominantly globo-series glycolipids, including Gb3, Gb5 (IV3GalGb4), globo-ganglioside (IV3NeuAc alpha 2----3GalGb4), globo-H (IV3Fuc alpha 1----2GalGb4), and globo-A (IV3GalNAc alpha 1----3[Fuc alpha 1----2]GalGb4). When NTERA-2 cells were induced to differentiate by culturing in the presence of 10(-5) M retinoic acid, a remarkable shift of cellular glycolipids from globo-series to lacto- and ganglio-series was observed: Globo-series structures declined, particularly during the period 7-20 days after first exposure to retinoic acid, while lacto-series structures, including fucosyl alpha 1----3 type 2 chain (Lex) and sialosyl type 2 chain, and ganglio-series structures, including GM3, GD3, 9-O-acetyl-GD3, GM2, GD2, and GT3, increased. The presence of globo-A and globo-H as the major ABH blood group antigens in undifferentiated NTERA-2 cells suggests that globo-series blood group antigens are embryonic antigens, synthesis of which switches to lacto-series during human development. Two-color immunofluorescence analysis indicated preferential expression of several ganglio- and lacto-series antigens on different subsets of differentiated cells and permitted the relationship of these subsets to the development of neurons in NTERA-2 cultures to be determined. The results suggest that glycosyltransferase, particularly those involved in controlling glycoconjugate core structure assembly, are key enzymes regulated during the differentiation of human EC cells and, by implication, during human embryogenesis.