GANGLIOSIDE ALTERATIONS IN YAC-1 CELLS CULTIVATED IN SERUM-SUPPLEMENTED AND SERUM-FREE GROWTH-MEDIUM

Gangliosides of the 'G(M1b)-pathway' (G(M1b) and GalNAc-G(M1b)) have been found to be highly expressed by the mouse T lymphoma YAC-1 grown in serum-supplemented medium, whereas G(M2) and G(M1) ('G(M1a)-pathway') occurred only in low amounts [Muthing, J., Peter-Katalinic, J., Hanisch, F.-G., Neumann, U. (1991) Glycoconjugate J 8:414-23]. Considerable differences in the ganglioside composition of YAC-1 cells grown in serum-supplemented and in well defined serum-free medium were observed. After transfer of the cells from serum-supplemented medium (RPMI 1640 with 10% fetal calf serum) to serum-free medium (RPMI 1640 with well defined supplements), G(M1b) and GalNAc-G(M1b) decreased and only low amounts of these gangliosides could be detected in serum-free growing cells. The expression of G(M1a) was also diminished but not as strongly as that of G(M1b) and GalNAc-G(M1b). These growth medium mediated ganglioside alterations were reversible, and the original ganglioside expression was achieved by readaptation of serum-free growing cells to the initial serum-supplemented medium. On the other hand, a 'new' ganglioside, supposed to represent GalNAc-G(D1a). and not expressed by serum-supplemented growing cells, was induced during serum-free cultivation, and increased strongly after readaptation. These observations reveal that the ganglioside composition of in vitro cultivated cells can be modified by the extracellular environment due to different supplementation of the basal growth medium.