Molecular mechanism of TGF-β signaling pathway in colon carcinogenesis and status of curcumin as chemopreventive strategy

Colon cancer is one of the third most common cancer in man, the second most common cancer in women worldwide, and the second leading cause of mortality in the USA. There are a number of molecular pathways that have been implicated in colon carcinogenesis, including TGF-beta/Smad signaling pathway. TGF-beta (transforming growth factor-beta) signaling pathway has the potential to regulate various biological processes including cell growth, differentiation, apoptosis, extracellular matrix modeling, and immune response. TGF-beta signaling pathway acts as a tumor suppressor, but alterations in TGF-beta signaling pathway promotes colon cancer cell growth, migration, invasion, angiogenesis, and metastasis. Here we review the role of TGF-beta signaling cascade in colon carcinogenesis and multiple molecular targets of curcumin in colon carcinogenesis. Elucidation of the molecular mechanism of curcumin on TGF-beta signaling pathway-induced colon carcinogenesis may ultimately lead to novel and more effective treatments for colon cancer.