Estramustine Phosphate Inhibits TGF-β-Induced MouseMacrophage Migration and Urokinase-Type PlasminogenActivator Production

Transforming growth factor-beta (TGF-β) has been demonstrated as a key regulator of immune responses including monocyte/macrophage functions. TGF-βregulates macrophage cell migration and polarization, as well as it is shown to modulatemacrophage urokinase-type plasminogen activator (uPA) production, which also contributes to macrophage chemotaxis andmigration toward damaged or inflamed tissues. Microtubule (MT) cytoskeleton dynamic plays a key role during the cellmotility, and any interference on the MT network profoundly affects cell migration. In this study, by using estramustinephosphate (EP), which modifies MT stability, we analysed whether tubulin cytoskeleton contributes to TGF-β-inducedmacrophage cell migration and uPA expression. We found out that, in the murine macrophage cell line RAW 264.7, EP atnoncytotoxic concentrations inhibited cell migration and uPA expression induced by TGF-β. Moreover, EP greatly reduced thecapacity of TGF-βto trigger the phosphorylation and activation of its downstream Smad3 effector. Furthermore, Smad3activation seems to be critical for the increased cell motility. Thus, our data suggest that EP, by interfering with MT dynamics,inhibits TGF-β-induced RAW 264.7 cell migration paralleled with reduction of uPA induction, in part by disabling Smad3activation by TGF-β.