The
glycosphingolipid patterns were analyzed on two clones derived from a human
melanoma cell line and selected for their respectively high and low metastatic ability in immunosuppressed newborn rats. Conversely to the weakly metastatic cells which exhibited a pattern similar to that of the parental cell line, highly metastatic human
melanoma cells appeared to be deficient in
ganglioside biosynthesis. An accumulation of
lactosylceramide was found in the latter cells, with low amounts of GM3 as the only
ganglioside detected and a fourfold decreased activity of
GM3 synthase (EC 2.4.99.9). After
subcutaneous injection of metastatic cells in newborn rats, the cells proliferating in the
tumor induced at the injection site re-expressed the four common
gangliosides of
melanoma: GM3, GM2, GD3 and GD2, whereas the cells growing in the lungs as metastatic nodules were deficient in
ganglioside synthesis and showed an accumulation of
lactosylceramide. Taken together, our results suggest that the human
melanoma cells which are able to escape from the primary
tumor and invade the lungs have an impaired
ganglioside biosynthesis with a deficient
GM3 synthase.