Role of Transforming Growth Factor-β in Epithelial-Mesenchymal Transition of Human Cancers - A Brief Review

Epithelial Mesenchymal Transition (EMT) is a crucial process in embryogenesis, however it also plays an important role in pathologies including inflammation, wound healing and cancer. EMT is a determining step in cancer metastasis as tumour cells utilise the process of EMT for invasion, migration and colonization at distant sites. The transforming growth factor-β (TGF-β) is a pleiotropic inflammatory cytokine belonging to the TGF-β super family of growth and differentiation factors secreted by immune, non-hematopoietic and tumour cells. Three TGF-β isoforms, TGF-β1, TGF-β2, and TGF-β3 are recognized in mammals. TGF-β induced signalling pathways remains the most prominent among other pathways inducing EMT. The TGF-β induced signaling pathways are inducted in all three types of EMT including the physiological embryogenesis process and pathological process such as wound healing and tumorogenesis. TGF-β acts via the SMAD and Non-SMAD pathways and plays major roles in tumour infiltration and metastasis. This article aims to briefly review the role of TGF- β induced signalling pathways and its role in tumour progression in human cancers such as lung cancer, breast cancer and oral squamous cell carcinoma.