TGF-β induces fascin expression in gastric cancer via phosphorylation of smad3 linker area

Background: Fascin is an actin-bundling protein critical for tumor invasion. TGF-beta could induce fascin expression in gastric cancer cells. In this study, we attempted to explore the role of p-smad3L in the expression of fascin induced by TGF-beta in gastric cancer cells. Methods: Pseudopodia were evaluated by immunofluorescence. Fascin expression was detected by RT-PCR and western blot. Smad3 siRNA was used to repress the endogenous smad3. The phosphorylations of smad3 linker region at sites s204, s208 and s213 were detected by western blot. The fascin promoter reporter activity was measured by dual luciferase assay. Results: TGF-beta could increase the formation of pseudopodia and the expression of fascin in gastric cancer cells. Smad3 depletion abrogated the expression of fascin induced by TGF-beta. The phosphorylation of smad3 linker region at serine 204, 208 and 213 was enhanced in gastric cancer cells after TGF-beta treatment. The fascin promoter reporter activity was significantly enhanced with TGF-beta treatment in both wild-type Smad3 group and Smad3EPSM group (P<0.05). Furthermore, the fascin promoter reporter activity in the wild-type Smad3 transfectant cells was significantly higher than that in Smad3EPSM cells (P<0.05). Conclusions: fascin expression induced by TGF-beta depends on smad3, at least in part, depends on smad3 linker phosphorylation.