NIBP impacts on the expression of E-cadherin, CD44 and vimentin in colon cancer via the NF-κB pathway.

NIBP, a novel nuclear factor-κB (NF-κB)-inducing kinase (NIK) and IκB kinase ß (IKKß) binding protein, directly interacts with NIK and IKKß, and acts as the 'bridge' of the NF­κB classical and alternative signaling pathways. However, its influence on epithelial­mesenchymal transition markers in colon cancer remains to be fully elucidated. The aim of the present study was to investigate the roles of NIBP impacting on the expression of E­cadherin, CD44 and vimentin. In the present study, the associations between NIBP and E­cadherin, CD44 and vimentin in clinical samples were analyzed by making pairwise comparisons between normal colon tissue, non­metastatic colon cancer tissue and metastatic colon cancer tissue. In in vitro experiments, after changing the expression of NIBP in cells, the protein expression levels of CD44, vimentin, E­cadherin were analyzed by western blot analysis. The results revealed that the protein expression levels of NIBP, CD44 and vimentin were markedly increased, and E­cadherin was markedly decreased, in metastatic colon cancer tissue compared with normal colon tissue and non­metastatic colon cancer tissue. Upregulation of NIBP expression decreased the levels of E­cadherin, whereas the downregulation of NIBP increased E­cadherin levels, while no significant differences were observed in the levels of CD44 and vimentin. In addition, cells that were treated with the NF­κB inhibitor, pyrrolidine dithiocarbamate (PDTC), also tended to exhibit increased levels of CD44 and vimentin expression in the NIBP upregulated expression group (29­NIBP group) compared with the mock group, whereas the expression levels of E­cadherin, CD44 and vimentin were similar in the NIBP downregulated expression group (116­NIBPmir group) and the HCT116 blank control group (116­mock group) on treatment of the cells with tumor necrosis factor­α. These findings indicated that NIBP, E­cadherin, CD44 and vimentin are possibly associated with metastasis in colon cancer. When the NF­κB pathway is not subjected to any interventions, NIBP may predominantly regulate the NF­κB classical pathway, rather than the alternative pathway. When the classical pathway was completely inhibited, NIBP was able to activate the NF­κB alternative pathway. NIBP is therefore necessary for the interaction between the NF­κB classical and alternative pathways. In conclusion, NIBP impacts on the expression levels of E­cadherin, CD44 and vimentin via the NF­κB classical and alternative pathways. Therapeutic regimens for patients with colorectal cancer may comprise NIBP inhibitors in the future.