Enhanced differentiation of HL-60 leukemia cells to macrophages induced byciprofibrate

Ciprofibrate, an hypolipidaemic peroxisome proliferator, induced differenti ation of HL-60 cells. The effect was greatly potentiated by phorbol 12-myri state W-acetate at a concentration where neither phorbol ester nor ciprofib rate alone had any effect on these cells. As occurs for HL-60 cell differen tiation induced by high phorbol ester concentration, the ciprofibrate-induc ed phorbol eater-dependent differentiation of HL-60 cells proceeded through the monocytic/macrophage pathway and induced the phosphorylation of protei ns with similar molecular weights suggesting that increased protein kinase C activity may be involved in the effect, The peroxisome proliferator-activ ated receptor (PPAR alpha) transcription factor is expressed in HL-60 cells , but no changes were observed in its expression upon HL-60 cell differenti ation.