Abstract 3906: Inhibition ofNF-kB Inducing Kinase (NIK) to supressNF-kB alternative pathway and cell migration in HNSCC
Authors: Das Rita , Clavijo Paul E. , Allen Clint , Saleh Anthony , Chen Zhong , Waes Carter Van 
Published: August 2018

Abstract
Nuclear factor-κB (NF-κB) activation through the alternative pathway has been implicated in cancer progression and survival, however the regulatory signaling and biological significances are not well understood, especially in head and neck squamous cell carcinoma (HNSCC). NF-κB-inducing kinase (NIK) is a key molecule in the alternative NF-κB pathway, which receives signals from Lymphotoxin beta/Lymphotoxin beta receptor (LTβ/LTβR) to activate Inhibitor-κB kinase α (IKKα) and transcription factors RELB/NF-κB2. In a panel of HNSCC cell lines, we observed that dysregulation of the alternative NF-κB pathway occurred primarily through increased LTβ receptor signaling via NIK and the non-canonical NF-κB subunits. We identified a NIK inhibitor 1, 3[2H, 4H]-Iso-Quinoline Dione, which inhibited cell migration at a low dose range, but exhibited minimal anti-proliferative effect in HPV(-) HNSCC cell lines. The biological effects of the inhibitor were through suppression of the alternative NF-κB signaling. Using Western blot and immunofluorescence staining, we showed that the inhibitor reduced the protein expression and/or phosphorylation of NIK, IKKα, and RELB/NF-κB2 (p52) in the cytoplasm, and/or the protein translocation in the nucleus. The NIK inhibitor also blocked LTβ induced translocation of RELB to the nucleus. The effects of NIK inhibitor were validated by knockdown of NIK using siRNA, which inhibited cell migration and LTβ-induced expression of MET. Met is a hepatocyte growth factor receptor implicated in promoting metastasis, and knockdown of MET slowed down HNSCC cell migration. We further extended the study on a murine oral metastasis cell line MOC2, which is a syngeneic mouse model suitable for testing drug effects on tumor growth and migration in vivo. We found that the NIK inhibitor decreased cell proliferation, migration, and invasion through an extracellular matrix barrier at low concentration ranges. Currently, we have identified a potent and selective small molecule NIK inhibitor, which is orally bioavailable and active in vivo. We plan to test the effects of this NIK inhibitor on HNSCC tumor growth and metastasis in the syngeneic MOC2 model. Our study may shed light on how HNSCC tumors migrate and metastasize to local lymph nodes, where the microenvironment promotes alternative NF-κB activation by LTβ through NIK signaling. Targeting NIK mediated alternative NF-κB activation could be a potential therapeutic strategy for preventing tumor migration and metastasis of HNSCC. (Supported by NIDCD intramural projects ZIA-DC-000016, 74)
Citation Format: Rita Das, Paul E. Clavijo, Clint Allen, Anthony Saleh, Zhong Chen, Carter Van Waes. Inhibition ofNF-kB Inducing Kinase (NIK) to supressNF-kB alternative pathway and cell migration in HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3906.