Organization and neuraminidase susceptibility of sialic acid residues in human melanoma cell lines with different heterotransplantabilities in nude mice.

Quantitative analyses of sialic acid residues expressed at the surface of human melanoma cells have been performed on 6 cell lines differing in their ability to grow subcutaneously in nude mice. Whereas 3 of these cell lines showed low heterotransplantability (LT), 3 other cell lines showed high heterotransplantability (HT). It was found by several methodologic approaches that the 6 human melanoma cell lines varied significantly in their amount of sialic acid susceptible to Vibrio cholerae neuraminidase, but had similar amounts of total sialic acid residues. Cells in the LT group exhibited twice as much cell surface sialic acid residue susceptible to this enzyme as cells in the HT group. Specific fluorescent labeling of external cell surface sialic acid residues showed that the LT cells present a patch-like distribution of the label, whereas the HT cells are characterized by a more homogeneous distribution of the label. Thus the human melanoma cell lines could be distinguished not only by their heterotransplantability in nude mice but also by membrane properties, such as the topographic organization of their cell surface sialic acid residues.