Evidence that TNF-β induces proliferation in colorectal cancer cells and resveratrol can down-modulate it

Abstract

Although much is understood about the proinflammatory cytokine TNF-α, very limited data are available about TNF-β (lymphotoxin). Whether TNF-β can induce the proliferation of tumor cells, how TNF-β-induced proliferation of tumor cells is affected by natural products such as resveratrol and the role of NF-κB in this process, is not understood. In the present study, we used clonogenic and cytotoxic methods to show the effect of TNF-β on cell proliferation. We also examined the impact of resveratrol on TNF-β-promoted proliferation and on NF-κB activation in HCT116 colorectal cancer (CRC). Our findings showed that TNF-β induced the proliferation and invasion in CRC cells and this was comparable with that of TNF-α. TNF-β-stimulated proliferation of CRC cells was blocked via anti-TNF-β-receptor. We found that resveratrol reversed the TNF-β-induced proliferation and invasion of CRC cells, and this correlated with the suppression of TNF-β-stimulated NF-κB signaling. Like resveratrol, IκB-kinase (IKK) inhibitor (BMS-345541), also reversed TNF-β-stimulated proliferation, NF-κB activation and these were mediated through inhibition of IκB-kinase, phosphorylation of IκBα, suppression of phosphorylation, and nuclear translocation of the p65 subunit of NF-κB. Furthermore, resveratrol similar to BMS-345541 suppressed TNF-β-promoted NF-κB-mediated gene biomarkers linked with proliferation, apoptosis, and invasion. Overall, our findings indicate for the first time that TNF-β/TNF-β-receptor signaling is involved in proliferation of CRC cells in parallel to TNF-α, and that resveratrol down-modulates TNF-β/TNF-β-receptor-mediated inflammatory response, at least in part through down modulating NF-κB activation, thereby regulating tumor cell growth. Impact statement The mechanism by which natural products such as resveratrol suppresses TNF-β-promoted tumor cell proliferation, invasion, and colony formation is unknown. In this study, we explored for the first time the effect of resveratrol on the proinflammatory cytokine TNF-β-, compared to TNF-α-stimulated proliferative and pro-inflammatory signaling in HCT116 cells. Our findings suggest that expression of TNF-β and TNF-β-receptor, like TNF-α, can lead to activation of inflammatory transcription factor (NF-κB) and NF-κB-regulated gene biomarkers, which are involved in the promotion of cancer proliferation, invasion, metastasis, and cell survival of tumor. Resveratrol can block TNF-β/TNF-β-receptor-induced activation of NF-κB, NF-κB-modulated gene products, and inhibition of caspase-3 cleavage. These results highlight the therapeutic effect of resveratrol-mediated anti-tumor activity by multitargeting cellular signaling pathways.