Glycosphingolipids in Bomirski transplantable melanomas in hamsters.

The glycosphingolipid compositions of Bomirski melanomas at different stages of differentiation, including Ab amelanotic melanoma (fast growing), Ma melanotic melanoma (slow growing), and MI hypomelanotic melanoma (slow growing), were studied. The total concentration of lipid-bound sialic acid in Ab amelanotic melanoma was found to be much lower than those in Ma and MI melanomas (0.8 micrograms versus 1.4 micrograms and 1.4 micrograms/mg of dry tissue, respectively). The ganglioside patterns in melanoma tissues were composed mainly of three components, which were confirmed as NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer (GM3), acetyl1-9-O-NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer (9-O-acetyl-GD3), and NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer(GD3) by structural analysis and monoclonal antibody detections. However, the relative ratios of these gangliosides expressed in the different types of melanomas were completely different. The MI melanoma tissues contained GM3 as the predominant species (greater than 90% of the total gangliosides) with very little of GD3 and 9-O-acetyl-GD3 gangliosides (less than 2% of the total gangliosides). In contrast, Ab amelanotic melanomas contained mainly 9-O-acetyl-GD3 (greater than 27%) and GD3 (greater than 51%) with lesser amounts of GM3. However, Ma melanoma had intermediate levels of GM3, GD3, and 9-O-acetyl GD3. The MI and Ma melanomas also contained monohexosylceramide (GL1) (about 60% as Gal beta 1-1'Cer and 40% as Glc beta 1-1'Cer in Ma and 30% as Gal beta 1-1'Cer and 70% as Glc beta 1-1'Cer in MI) and Gal beta 1-4Glc beta 1-1'Cer as the predominant neutral glycosphingolipid species. In contrast, Ab melanoma tissues contained more GalNAc beta 1-3GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1-1'Cer (Gb5), Gal alpha 1-4Gal beta 1-4Glc beta 1-1'Cer (Gb3), and GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1-1'Cer (Gb4) than MI and Ma melanomas. Our data suggest that the expression of glycosphingolipids in hamster melanoma cells may be closely related to cell growth and the degree of differentiation, with slow growing, highly differentiated cells expressing GM3 and GL1, and fast growing, undifferentiating cells having a preponderance of GD3, 9-O-acetyl-GD3, Gb5, Gb3, and Gb4.