TGF-ß: an emerging player in drug resistance.

The transforming growth factor ß (TGF-ß) pathway acts as a double-edged sword in tumorigenesis. By constraining epithelial cell growth, TGF-ß is a potent tumor suppressor. However, TGF-ß also acts as a key player in the induction of epithelial-to-mesenchymal transition (EMT), thereby enhancing invasiveness and metastasis. Furthermore, TGF-ß signaling has recently been correlated with resistance against both targeted and conventional anticancer agents. Here, we present data demonstrating a role for TGF-ß in chemotherapy resistance in colorectal cancer (CRC). We discuss these results in the context of recent findings indicating TGF-ß signaling as an emerging player in cancer drug resistance.