Microtubule-disrupting agents reverse the inhibitory effect of interferon on mitogenesis in 3T3 cells

Interferon can inhibit the stimulation of DNA synthesis in quiescent 3T3 cells exposed to combinations of purified growth factors, but the extent of inhibition varies with the number and combination of mitogens used. As the number of growth factors used to stimulate the cells is increased from two to three, the inhibitory effect of IFN is reduced, and if the third mitogen is a microtubule-disrupting agent such as colchicine or nocodazole, it is abolished altogether. The antagonistic effect of microtubule-disrupting agents on interferon-induced inhibition of DNA synthesis suggests that an intact tubulin network is required for this action of interferon. Interferon and tubulin disrupting agents also show similar kinetics in establishing an effect on DNA synthesis which could imply that they have opposite effects on tubulin assembly.