TGF-β signalling and its role in cancer progression and metastasis

The transforming growth factor-beta (TGF-beta) system signals via protein kinase receptors and SMAD mediators to regulate a large number of biological processes. Alterations of the TGF-beta signalling pathway are implicated in human cancer. Prior to tumour initiation and early during progression, TGF-beta acts as a tumour suppressor; however, at later stages, it is often a tumour promoter. Knowledge about the mechanisms involved in TGF-beta signal transduction has allowed a better understanding of cancer progression, invasion, metastasis and epithelial-to-mesenchymal transition. Furthermore, several molecular targets with great potential in therapeutic interventions have been identified. This review discusses the TGF-beta signalling pathway, its involvement in cancer and current therapeutic approaches.