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 M 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.