Transforming growth factor-β signals promote progression of squamous cell carcinoma by inducing epithelial-mesenchymal transition and angiogenesis

At present, the molecular mechanisms driving the progression and metastasis of oral squamous cell carcinoma (OSCC) remain largely uncharacterized. The activation of transforming growth factor-β (TGF-β) signaling in the tumor microenvironment has been observed in various types of cancer and has been implicated their progression by enhancing the migration and invasion of epithelial cancer cells. However, its specific roles in the oral cancer progression remain unexplored. In this study, we examined the effects of TGF-β signaling on the murine squamous cell carcinoma, SCCVII cells in vitro and in vivo. The incubation of SCCVII cells with TGF-β induced the activation of TGF-β signals and epithelial-mesenchymal transition (EMT). Notably, the motility of SCCVII cells was increased upon the activation of the TGF-β signaling. RNA sequencing revealed upregulation of genes related to EMT and angiogenesis. Consistent with these in vitro results, the inhibition of TGF-β signals in SCCVII cell-derived primary tumors resulted in suppressed angiogenesis. Furthermore, we identified six candidate factors (ANKRD1, CCBE1, FSTL3, uPA, TSP-1 and integrin β3), whose expression was induced by TGF-β in SCCVII cells, and associated with poor prognosis for patients with head and neck squamous cell carcinoma. These results highlight the role of TGF-β signals in the progression of OSCC via multiple mechanisms, including EMT and angiogenesis, and suggest novel therapeutic targets for the treatment of OSCC.