TGF-β Signal Transduction in Pancreatic Carcinoma Cells is Sensitive to Inhibition by the Src Tyrosine Kinase Inhibitor AZM475271.

Abstract

Earlier results from our group have shown that in pancreatic ductal adenocarcinoma (PDAC)-derived cells transforming growth factor (TGF)-β1-dependent epithelial-mesenchymal transition (EMT) and cell motility was inhibited by the Src inhibitors PP2 and PP1 both of which targeted the TGF-β receptors for inhibition. In this study we evaluated the impact of another Src inhibitor, AZM475271, on various TGF-β responses in PDAC cells. The effect of AZM475271 on TGF-β1-induced random cell migration (chemokinesis), the expression of EMT and migration/invasion-associated genes, TGF-β-induced luciferase activity, and C-terminal phosphorylation of Smad2 and Smad3 was measured in the PDAC-derived Panc-1 and Colo357 cell lines using real-time cell migration assays, quantitative real-time PCR, luciferase reporter gene assays and phosphoimmunoblotting, respectively. AZM475271 effectively blocked TGF-β1-induced chemokinesis of Panc-1 cells in a dose-dependent fashion and inhibited the high chemokinetic activity of Panc-1 cells with ectopic expression of a constitutively active ALK5T204D mutant. AZM475271 but not another Src inhibitor, SU6656, partially relieved the suppressive effect of TGF-β1 on E-cadherin and inhibited TGF-β1-induced upregulation of the MMP2, MMP9, N-cadherin and vimentin genes, activity of a TGF-β1-dependent reporter gene, and activation of Smad2 and Smad3. Our data suggest that AZM475271 cross-inhibits tumor-promoting TGF-β signaling and may thus function as an inhibitor of both TGF-β and Src in both experimental and clinical therapies against metastatic dissemination in late-stage PDAC.