Differences in lipid characteristics of autologous human melanoma cell lines with distinct biological properties

Significant differences in lipid composition were found when six established human melanoma cell lines were compared. A pair of cell lines was initiated from a superficial spreading melanoma and the lymph node of the same patient; four others were also autologous, three of which originated from the same nodular melanoma and the other from its metastasis. Cell lines varied in pigmentation level and ability to grow in nude mice. Cell lines contained similar amounts of total cholesterol, glycerides, and phospholipids but different amounts of free cholesterol and cholesterol esters. In particular, the molar ratio of free cholesterol to phospholipid was increased in highly tumorigenic cell lines. No changes in phospholipid profiles were noted among cell lines, except an increase in sphingomyelin with a concomitant decrease in phosphatidylcholine in one cell line compared to the profiles of its counterpart cell line. The saturated-to-unsaturated fatty acid ratios in phosphatidylcholine and phosphatidylethanolamine were similar in all cell lines, but the monounsaturated-to-polyunsaturated fatty acid ratio in phosphatidylcholine was increased in highly tumorigenic cell lines. A significant variation in the latter ratio in phosphatidylethanolamine was also observed in the pair of autologous cell lines. These changes were unrelated to a depletion in linoleic acid in culture medium. Results obtained by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene were consistent with the differences in lipid composition between two autologous cell lines. The present results indicate that two lipid characteristics were significantly changed in highly tumorigenic cell lines as compared to cell lines with low tumorigenicity, but no correlation was found between either pigmentation level or origin (primary or metastatic) and lipid composition.