Dissociation of human cytokine receptor expression and signal transduction

We have examined the relationship between granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) receptor expression and signal transduction in populations of HL-60 cells differing in proliferative capacity to these cytokines. GM-CSF or IL-3 stimulation of HL-60 cells pretreated with either dimethyl sulfoxide (DMSO) or retinoic acid results in increases in proliferative response as well as both tyrosine and serine phosphorylation. In contrast, neither GM-CSF or IL-3 stimulation of parental HL-60 cells (those not treated with DMSO or retinoic acid) produced any changes in either proliferation or protein phosphorylation. Thus, although parental HL-60 cells expressed both GM-CSF and IL-3 receptors, treatment with either DMSO or retinoic acid was necessary to confer the capacity for signal transduction as assessed by both a biologic and biochemical response. Pretreatment of cells with genistein, a protein tyrosine kinase inhibitor, resulted in inhibition of GM-CSF-induced protein tyrosine phosphorylation as well as proliferation. These data show a strong correlation between cytokine-induced increases in protein phosphorylation and subsequent biologic responses. Further, this work demonstrates that cytokine receptor expression and signal transduction can be disassociated and suggests the potential for independent regulation of these two components of signal transduction.