Cyclic Nucleotide-induced Maturation of Human Promyelocytic Leukemia Cells

Abstract

Myeloid differentiation in vitro is characterized by the sequential appearance of morphological, functional, and biochemical markers of maturation. We examined the effect of agents that increased the intracellular concentration of adenosine 3′5′-cyclic monophosphate on the expression of these markers by human promyelocytic leukemia cells (HL60). Cells treated with 500 μM N⁶,O²-dibutyryl adenosine 3′5′-cyclic monophosphate expressed formyl peptide and complement receptors, reduced nitroblue tetrazolium, adhered to substrate, demonstrated chemotaxis and stimulated lysosomal enzyme release, rapidly ceased proliferation, and assumed the morphology of myelocytes and metamyelocytes. Prostaglandin E₂ (100 nM) and theophyllin (500 μM) induced similar functional changes but the cells did not mature beyond the myelocyte stage. Cholera toxin (1 or 50 nM) induced formyl-peptide receptor expression and adherence, but the cells did not reduce nitroblue tetrazolium, continued to proliferate, and were unchanged morphologically. Formyl-peptide receptor expression was the earliest marker of these modified programs of maturation. The receptor appeared within 2 h after treatment and increased linearly for 72 h. Receptor expression was dependent on new protein synthesis. At 48 h, Scatchard analysis demonstrated 2.4 × 10⁵ receptors/ cell with a K_D of 1.3 nM. In contrast to induction of HL60 differentiation by dimethyl sulfoxide, retinoic acid, or phorbol myristate acetate, the developmental programs initiated by agents that raised intracellular adenosine 3′5′-cyclic monophosphate shared several unique features: (a) plasma membrane maturation was dissociated from morphological maturation; (b) no latent period was evident following induction—the earliest membrane marker was expressed within 2 h; (c) commitment to terminal differentiation was delayed.