Differentiation Of Leukemia HL-60 Cells Research Articles

Appearance of membrane-bound tyrosine kinase during differentiation of HL-60 leukemia cells by immune interferon and tumor necrosis factor

The effect of immune interferon (IFN-γ) and recombinant tumor necrosis factor (rTNF-α) on cellular differentiation was investigated in human promyelocytic leukemia cell line HL-60. Both IFN-γ and rTNF-α induced the appearance of the monocytic phenotype in a dose- and time-dependent manner as assessed by morphology, reduction of nitroblue tetrazolium and the induction of α-naphthyl butyrate esterase. Utilizing a nondenaturing polyacrylamide electrophoretic assay, it was revealed that a membrane-bound tyrosine kinase activity accompanied the appearance of the differentiated cell type. These results suggest that the induction of membrane-bound tyrosine kinase activity by IFN-γ and rTNF-α may be an important characteristic of monocytic differentiation.

Regulation of protein phosphotyrosine content by changes in tyrosine kinase and protein phosphotyrosine phosphatase activities during induced granulocytic and monocytic differentiation of HL-60 leukemia cells

About 1.5% of phosphorylated amino acid residues of HL-60 promyelocytic leukemia cells are phosphotyrosine. Induction of granulocytic differentiation by exposure to dimethylsulfoxide decreased tyrosine phosphorylation to 0.2%. A maximum 3-fold increase in tyrosine kinase activity and a 7-fold increase in protein phosphotyrosine phosphatase activity accompanied this change. Monocytic differentiation induced by 12-O-tetradecanoylphorbol-13-acetate, caused a decrease in phosphotyrosine levels to 0.1%; tyrosine kinase activity maximally increased 2-fold, and protein phosphotyrosine phosphatase activity increased 11-fold in these differentiated cells. Thus, although total tyrosine kinase activity markedly increased during differentiation, this was counteracted by an even greater elevation in protein phosphotyrosine phosphatase activity. The findings support the concept that tyrosine phosphorylation is important in the regulation of growth and differentiation of leukemia cells.

Retinoic acid promotes phorbol ester-initiated macrophage differentiation in HL-60 leukemia cells without disappearance of protein kinase C

The ability of retinoic acid (RA) to promote 12- O-tetradecanoyl-phorbol-13-acetate (TPA)-initiated macrophage differentiation was examined in human promyelocytic leukemia cell line HL-60. One-hour exposure to 10 nM TPA and subsequent exposure for 48 h to 1 μM RA following removal of TPA rapidly induced the macrophage phenotype in 65% of the cells. This effect was comparable to continuous exposure for 48 h to TPA alone, but contrasted with the absence of macrophage-like cells after RA treatment alone or the induction of 10% of the cell population to a macrophage phenotype after 1-h exposure to TPA. The effect of TPA + RA was accompanied by increased cell adherence and increased nonspecific esterase activity but not by a change in the reduction of nitroblue tetrazolium. Protein kinase C (PK-C) activity was increased 35–40% in cells treated for 1 h with TPA alone or after subsequent exposure to RA. Cells treated for 48 h with RA exhibited a 2-fold increase in PK-C activity while cells exposed to TPA for 48 h lost all PK-C activity. The changes in PK-C activity in TPA + RA-treated cells were accompanied by Ca 2+/phospholipid(PL)-dependent phosphorylation in vitro of pp38 which is characteristic of treatment with RA alone, as well as the Ca 2+/PL-independent phosphorylation in vitro of pp82 and pp130 (vinculin) which is prevalent in cells treated continuously with TPA alone and is absent in RA-treated cells. These results indicate that the macrophage phenotype induced by TPA + RA is similar to that produced by continuous exposure to TPA alone with respect to their in vitro phosphoprotein patterns, cytochemical markers, cell adherence and morphology, but that the disappearance of PK-C is not an obligatory characteristic of these cells.

Induction of differentiation and inhibition of DNA methylation in HL-60 myeloid leukemic cells by 5-AZA-2′-deoxycytidine

The effects of 5-AZA-2′-deoxycytidine (5-AZA-CdR) on the induction of morphological and biochemical differentiation and inhibition of DNA methylation of human HL-60 myeliod leukemic cells were investigated. 5-AZA-CdR at concentrations of 0.1–1 μg ml −1 for 48-h exposure produced significant morphological differentiation of HL-60 leukemic cells to a more mature phenotype, augmented the cell surface marker (OKMI) for mature granulocytes/monocytes and also increased the superoxide anion production. Under these same conditions 5-AZA-CdR inhibited the synthesis of 5-methylcytosine in DNA suggesting that there is a correlation between the induction of differentiation and inhibition of DNA methylation. At concentrations of 5-AZA-CdR that inhibit DNA methylation there was a marked decrease in colony-formation suggesting that the antileukemic action of this analog is related to the methylation of DNA.