Glycosphingolipids of cultured human colon carcinoma cells and their drug-resistant sublines

Human colon carcinoma cells were analyzed for lipid phosphorus, cholesterol and glycosphingolipids. Ceramide mono-, di- and trihexosides and sulfatides were isolated by column and thin-layer chromatography and determined quantitatively on the basis of their hexose content. The complex lipid fractions so isolated were only partially resolved with the material available. Gangliosides G_M2 and 6_M2 and globoside were major components of the fraction and were determined on the basis of their hexose, hexosamine and neuraminic acid content. The HCT 116, 116a and 116b cells contained no fucolipids. Cell lines resistant to mitomycin C, teniposide and etoposide were developed and analyzed. Over the 5 year period of the study sulfatides declined to about one-fourth of their original amounts in both parent and drug-adapted cells. HCT 116 cells adapted to mitomycin C and teniposide had 30% less ceramide monohexoside and a 45% greater cholesterol to lipid phosphorus ratio than the parent cells. Reductions in ceramide dihexoside in the drug-adapted cells were greater than those of the ceramide monohexoside. Galabiosyl ceramide was the major ceramide dihexoside in all the cells and accumulated in HCT 116a to levels 4-6-fold greater than that of the other lines as the only dihexoside.