Knockdown of NIK and IKKβ-Binding Protein (NIBP) Reduces Colorectal Cancer Metastasis through Down-Regulation of the Canonical NF-κΒ Signaling Pathway and Suppression of MAPK Signaling Mediated through ERK and JNK.

Abstract

Despite the identification of many signaling pathways involved in colorectal cancer (CRC) tumorigenesis, metastatic CRC still remains one of the major causes of cancer related death. NIK and IKKβ-binding protein (NIBP) is one of the key regulators of the NF-κB signaling pathway, which has been implicated in CRC metastasis. The aim of this study was to investigate the possible role of NIBP in CRC metastasis through its regulation of NF-κΒ and extracellular regulated kinase/c-Janus kinase (ERK/JNK) signaling pathways.In this study NIBP, phosphorylated (p)-p65, p-ERK1/2, and p-JNK1/2 expression was examined in 130 CRC, and 25 adenoma tissue samples were studied by immunohistochemistry. NIBP shRNA knockdown was performed in HCT116 cells, and NF-κB and ERK/JNK pathway activity was measured after TNF-α stimulation in vitro and in vivo.We found that NIBP, p-p65, p-ERK1/2, and p-JNK1/2 expression was higher in late stages of CRC compared to early stages or adenomas. Expression of p-p65, p-IκBα, p-IκBβ, p-ERK1/2, and p-JNK1/2 was inhibited in TNF-α stimulated HCT116 cells following NIBP knockdown. Nevertheless, p-ERK1/2 expression in un-transfected and NIBP knockdown HCT116 cells remained the same in the absence of TNF-α stimulation. Furthermore, cell motility and invasion were reduced in HCT116 cells following NIBP knockdown even after TNF-α treatment. Finally, primary tumor weight and liver metastasis were reduced in nude mice with orthotopically transplanted NIBP knockdown of HCT116 cells.In conclusion, we demonstrated that NIBP knockdown reduces colorectal cancer metastasis through down-regulation of canonical NF-κΒ signaling and suppression of ERK and JNK signaling.