Tumor necrosis factor-induced changes of gene expression in U937 cells. Differentiation-dependent plasticity of the responsive state.

TNF-alpha alone or in combination with IFN-gamma differentially affects the proliferation and differentiation of the human leukemic cell line U937 and two derivatives C27 and G3. All three cell lines express similar numbers of functional, high affinity receptors for both TNF-alpha and IFN-gamma. In C27 and G3 cells, TNF-alpha as well as IFN-gamma induced changes in steady state levels of specific mRNA, which appear to be associated with TNF-alpha and IFN-gamma diverse effects on cell growth and differentiation. Constitutive differences in membrane phosphorylation patterns suggest that altered transduction of TNF-alpha signals may account for the differential response of these three cell lines. Several lines of evidence indicate that C27 and G3 cells, when compared with parental U937 cells represent discretely higher stages of monocytic differentiation, suggesting that cellular differentiation may contribute to the development of resistance to the action of TNF-alpha.