5-Aminosalicylic acid inhibits TGF-β1 signalling in colorectal cancer cells

The transforming growth factor-β (TGF-β) pathway is an important pathway in the initiation and progression of colorectal cancer. We aimed to determine the effects of 5-aminosalicylic acid (5-ASA) on TGF-β signalling in colorectal cancer cells in vitro. 5-ASA inhibited TGF-β1 signalling in HCT116 cells and colonic fibroblasts, as judged by a TGF-β-specific reporter gene assay, plasminogen activator inhibitor-1 mRNA and protein levels, fibroblast trans-differentiation, Smad3 phosphorylation and nuclear translocation. We conclude that 5-ASA inhibits TGF-β1 signalling in colorectal cancer cells, and might be a potent adjuvant therapeutic drug, interfering with aberrant TGF-β signalling in colorectal cancer.