[Changes of PKC isoforms in induced differentiation of HL-60 cells by ATRA and PMA]

Human premyeloid leukemic cell line (HL-60) were differentiated along granulocytic or monocytic/phagocytic lineage respectively by the treatment of all-trans retinoic acid (ATRA) or phorbol ester (PMA), which was demonstrated by morphological observation, NBT reduction test, specific and nonspecific assay of esterases. By use of immuno-histochemical method, the changes of protein kinase C (PKC) isoforms alpha, beta I and beta II after induced differentiation of HL-60 cells were studied. The results showed that ATRA led to 5.0, 2.8 and 4.2 times increase of PKC alpha, beta I and beta II isoforms respectively as compared with the undifferentiated control levels and translocation of PKC from membrane to cytosol. The level of PKC alpha and beta II isoforms in HL-60 cells induced by PMA were decreased, but the expression of PKC beta I was increased. Besides, PMA led these 3 kinds of PKC to be present in cell nucleus with different intensity. These results suggest that the sustained activation of PKC alpha and beta may be required for granulocytic differentiation of HL-60 cells, while nuclear translocation of PKC may relatively be an important step for differentiation of HL-60 cells to monocytes/macrophages.