Suppression of LPS-induced tumor necrosis factor-alpha gene expression by microtubule disrupting agents

Microtubule disrupting agents such as colchicine have been shown to reduce TNF-alpha production in macrophages. To examine molecular mechanisms underlying the action of colchicine, TNF-alpha gene expression was studied in the murine macrophage cell line PU5-1.8. An LPS stimulation caused an intense up-regulation of TNF-alpha gene expression which was followed by a high TNF-alpha protein production. Simultaneous addition of colchicine (10 microM) suppressed LPS-induced TNF-alpha mRNA accumulation by one-third and TNF-alpha protein release by two-thirds. This effect was shared by vinblastine and vincristine, chemically different agents that also disrupt microtubule polymerization. For full suppressive activity on TNF-alpha gene expression, colchicine had to be present for 3 h in LPS-stimulated macrophage cultures. With nuclear run-on transcription experiments we could demonstrate that colchicine primarily inhibited de novo gene transcription and did not accelerate degradation of TNF-alpha mRNA in actinomycin D-treated macrophages. Thus, the well-known antiinflammatory action of microtubule depolymerizing agents may be largely due to a reduced TNF-alpha gene expression.