SIGNALING MECHANISM OF PMA-INDUCED DIFFERENTIATION OF K562 CELLS

We have studied the signaling pathways responsible for the monocytic a nd/or megakaryocytic differentiation of K562 cells. The results demons trated that although the mitogen-activated protein kinase (MARK) was a ctivated during the phorbol myristate acetate (PMA)-induced monocytic and/or megakaryocytic differentiation of K562 cells, the overexpressio n of Ha-ras which can activate the MAPK did not induce the monocytic a nd/or megakaryocytic differentiation of K562 cells. Instead PMA-induce d megakaryocytic differentiation of K562 cells was inhibited by the pr etreatment of pyrrolidine dithiocarbamate, a specific nuclear factor k appa B (NF-kappa B) inhibitor. Taken together, these results suggest t hat the activation of NF-kappa B rather than that of MAPK might be inv olved in the PMA-induced megakaryocytic differentiation of K562 cells. (C) 1996 Academic Press, Inc.