Induction of the Epithelial-to-Mesenchymal Transition of Human Colorectal Cancer by Human TNF-β (Lymphotoxin) and its Reversal by Resveratrol

Objective: Tumor necrosis factor-beta (TNF-beta), as an inflammatory mediator that has been shown to promote tumorigenesis, induces NF-kappa B. Natural multi-targeted agent resveratrol in turn shows anti-inflammatory and anti-cancer properties. Epithelial-to-mesenchymal transition (EMT) allows cancer cells to turn into a motile state with invasive capacities and is associated with metastasis and development of cancer stem cells (CSC). However, TNF-beta-induced EMT and the anti-invasion mechanism of resveratrol on CRC are not yet completely understood. Methods: We investigated the underlying molecular mechanisms of resveratrol on TNF-beta/TNF-beta R-induced EMT and migration of CRC cells (HCT116, RKO, SW480) in monolayer or 3D alginate cultures. Results: TNF-beta, similar to TNF-alpha, induced significant cell proliferation, morphological change, from an epithelial to a spindle-like mesenchymal shape with the formation of filopodia and lamellipodia associated with the expression of EMT parameters (elevated vimentin and slug, reduced E-cadherin), increased migration/invasion, and formation of CSC in all CRC cells. Interestingly, these effects were dramatically decreased in the presence of resveratrol or anti-TNF-beta R with TNF-beta co-treatment, inducing biochemical changes to the mesenchymal-epithelial transition (MET), with a planar cell surface and suppressed formation of CSC cells. This was associated with a significant increase in apoptosis. Furthermore, we found that resveratrol suppressed TNF-beta-induced NF-kappa B and NF-kappa B-regulated gene biomarkers associated with growth, proliferation, and invasion. Finally, TNF-beta R interacts directly with focal adhesion kinase (FAK) and NF-kappa B. Conclusion: These results suggest that resveratrol down-regulates TNF-beta/TNF-beta R-induced EMT, at least in part via specific suppression of NF-kappa Beta and FAK in CRC cells.