Inhibitors of polyamine biosynthesis block tumor necrosis factor-induced activation of macrophages

The activation of polyamine biosynthesis, dependent on increased gene expression of ornithine decarboxylase, has been found to play an important role in the control of cell proliferation and differentiation. In this report it has been found that accumulation of ornithine decarboxylase mRNA also follows stimulation of human monocytes/macrophages by tumor necrosis factor. Human recombinant tumor necrosis factor (100 units/ml) also evoked an enhanced respiratory burst of macrophages. The respiratory burst response was inhibited in a dose-dependent manner with difluoromethylornithine, an inhibitor of ornithine decarboxylase, and methylglyoxal-bis(guanylhydrazone), an inhibitor of the formation of spermidine and spermine. The data presented in this paper suggest that polyamines may play a functional role in tumor necrosis factor-driven macrophage activation, and they are discussed in the context of their possible use as inhibitors of polyamine metabolism in tumor chemotherapy.