Effects of ganglioside GM3 on phospholipid turnover of human leukemic J6-2 cells

Ganglioside GM3 was reported to induce the differentiation of HL-60 cells to differentiate along the macrophage-monocytic route. We used human monocytoid leukemia J6-2 cells and successfully induced differentiation by GM3. Because differentiation is accompanied by retarded growth rate and cell cycle is intimately related to phospholipid metabolism, so we explored how GM3 was related to phospholipid metabolism. By using [32P]Pi, [3H-CH3]choline, [3H-CH3]SAM, and [3H]inositol as radioactive tracers, we studied the turnover changes of phospholipids and their metabolites induced by GM3. For the morphological changes of differentiation to occur, the cells had to be treated with GM3 at a concentration of 50 microM for 5-6 days, but the phospholipid changes occurred at a very early stage of GM3 treatment (only 1 h). Our results indicate that GM3 stimulated PE methylation pathway inhibited both CDP-choline pathway and PI cycle. The phospholipid changes may constitute the early events in differentiation induced by GM3.