Differential changes in lipid metabolism ofmyeloid and lymphoid cell lines induced by treatment with 12- O-tetradecanoylphorbol-13-acetate (TPA)

Abstract

Treatment of the myeloid cell lines, U-937 or HL-60, with 10 nM of the phorbol ester, 12- O-tetradecanoylphorbol-13-acetate (TPA), for 24 h increased the rate of incorporation of [ 3H] glycerol into total chloroform extracts. A proportionally greater labeling of the non-polar lipid (NL) fraction compared to the polar, phospholipid (PL), fraction was observed. Chromatographic analysis showed a 6-fold increase in the labeling of triacylglycerols (TAG), a 2-fold increase in diacylglycerols, and no changes in monoacylglycerols. PL labeling showed a 3-fold increase in phosphatidylcholine (PC). The effect of TPA on TAG labeling was selectively observed in myeloid cell lines. No such a change was found in the lymphoid cell line, MOLT-3, which did respond to TPA with increased PC labeling. Incorporation of [ 3H]arachidonic acid (AA) into TAG by U-937 cells was selectively increased (2.5-fold) after treatment with TPA for 24 h. Treatment of U-937 cells with TPA in serum-free medium resulted in no increased labeling of TAG. These studies suggest that changes in TAG metabolism may be characteristic of myeloid differentiation and depend on the presence of serum factor(s).