We studied the role of
glycosphingolipids expressed on the cell surfaces of a metastatic tumor cell line.
Glycosphingolipid compositions of the low-metastatic murine
lymphosarcoma cell line RAW117-P and its sub-line, RAW117-H10, which shows higher metastatic potential for the liver than P cells, were compared. Both types of cells had LacCer, Gg3Cer, and
Gg4Cer as the major
neutral glycosphingolipids and
GM1b and
GD1alpha as the
gangliosides. There are differences in
glycosphingolipid contents, the neutral
glycosphingolipid contents in the parental cells being 1.5-fold higher than that in the variant ones. In contrast, the level of
GD1alpha in H10 cells was twice as much as that in the P cells; however, the expression of other
gangliosides was down-regulated. On the basis of the results of
glycosphingolipid analysis, we investigated the functional role of
GD1alpha in H10 cells in the adhesion of the
tumor cells to the target tissue by using hepatic sinusoidal endothelial (HSE) cells.
GD1alpha and
GM1b inhibited the adhesion when HSE cells were incubated prior to coculture with the
tumor cells. This inhibitory effect by
GD1alpha and
GM1b was observed within 30 min after addition of H10 cells to HSE cells and was dose dependent.
GD1alpha showed a higher inhibitory effect on the adhesion than
GM1b, whereas other
glycosphingolipids showed no inhibitory effect. Anti-GD1alpha
monoclonal antibody also inhibited the adhesion between the H10 and HSE cells. When cultured without
fetal bovine serum for 30 min in a various
glycosphingolipids-coated dish for bacterial culture, HSE cells adhered to the area coated with
GD1alpha but not to areas coated with other
glycosphingolipids. HSE cell adhesion depended on the amount of
GD1alpha coated on the plate. These data indicate that
GD1alpha functions as an adhesion molecule in the process of
metastasis of H10 cells.