In order to characterize the events which commit the HL60 human promyelocytic leukemia cell line to differentiate into macrophages or mature myeloid cells, we have analyzed the in vitro [35S]methionine-labeled translational products obtained from polyadenylated messenger RNA of the HL60 cells before and after exposure to: (a) dimethylformamide (DMF), an inducer of myeloid differentiation; (b) 12-O-tetradecanylphorbol-13-acetate (TPA), an inducer of macrophage differentiation; or (c) a combination of the two inducers. Exposure of the HL60 cells to either TPA or DMF results in decreases in the relative abundancy of translational products with molecular weights of 20,000, 17,000, and 15,000. Exposure of the HL60 cells so as to generate macrophage differentiation results in elevations of translational products with molecular weights of 60,000, 47,000, 42,000, 32,000, 27,000, 14,000, and 12,300, while DMF-induced myeloid differentiation is associated with increases in the abundancy of translational products with molecular weights of 60,000, 42,000, 35,000, 32,000, 27,000, 13,000 and 12,300. The addition of the macrophage inducer TPA to HL60 cells previously exposed to the myeloid inducer DMF results in changes in the relative abundance of several translational products, yielding a pattern which differs quantitatively from that obtained from cells treated with DMF or TPA alone. These changes in the relative abundancies of the HL60 translational products suggest that the steady state levels of several different populations of mRNA or the ability of these mRNAs to be translated are being modified during the induction of myeloid or macrophage differentiation in the HL60 promyelocytic leukemia cell line.


Supported in part by American Cancer Society Institutional Grant IN 127C.

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