Ganglioside composition of the rat choriocarcinoma cell line, Rcho-1

The Rcho-1 cell line, originally established from a rat choriocarcinoma, shows differentiation into placental trophoblastic giant cell-like cells and has been used to study the mechanism of placental function control. In the present study, we analysed the ganglioside composition of Rcho-1 cells by HPTLC orcinol/H₂SO₄, TLC/immunostaining and immunohistochemistry. Rcho-1 cells expressed GM3 and GD3 as the major gangliosides and CTH as major neutral glycolipid when they were cultured in growth medium (20% FCS) or transplanted beneath the kidney capsule. The expression of these gangliosides was strong in the undifferentiated small cells, whereas the completely differentiated giant cells showed poor staining with antibodies against the gangliosides. Under culture conditions to induce cell differentiation using horse serum (1-20% HS), the expression of GD3 was suppressed and re-expressed when the medium was changed to growth medium, suggesting that a change of ganglioside components may trigger and define the direction of terminal differentiation. Thus the composition of glycolipids is conserved in Rcho-1 cells and is similar to that of the rat placenta, where GM3 is dominant in mid-pregnancy and decreased in late pregnancy, whereas GD3 is low in mid- pregnancy and increased in late pregnancy.