Effects of colchicine on the induction of ornithine decarboxylase and its gene expression by the phorbol ester tumour promoter.

The activity and gene expression of ornithine decarboxylase (ODC, an indicator of tumour promotion) were induced by the phorbol ester tumour promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), in mouse skin. In the present study, the effect of colchicine, a microtubule-disrupting agent, on ODC activity and its gene expression were investigated. On administration of colchicine (100 micrograms) intraperitoneally 1.5 h before TPA treatment, ODC activity and ODC mRNA levels stimulated by TPA were suppressed to about 52 and 64%, respectively. These results suggest the involvement of a microtubule or colchicine-sensitive substrate in the signal transduction system for gene expression.