A Novel Tnik Inhibitor Potently Downregulates Cancer Stem Cell Population Through Attenuation Of Wnt Signaling

Background: TNIK (Traf2- and Nck-interacting kinase) has been identified as a component of the β-catenin and T-cell factor 4 (TCF4) complex that regulates the downstream of Wnt signaling. Recent studies indicated that the Wnt pathway is highly activated in cancer stem cells (CSCs), which have been recognized as the driving force of tumorigenesis and mediating tumor recurrence. Thus, eradicating CSCs by inhibiting Wnt signaling may become a new therapeutic option for a complete cure of cancers. Recently we have demonstrated that TNIK is required for the tumor-initiating function of colorectal CSCs, and therefore TNIK is considered to be attractive targets for drug discovery. We have discovered a thiazole-based TNIK inhibitor having potent inhibitory activity for the Wnt signaling. Further optimization of the thiazole-based TNIK inhibitor resulted in an orally available novel TNIK inhibitor, NC-1. In this study, we evaluated in vivo efficacy of the TNIK inhibitor in mouse models as well as its effects on CSCs in vitro. Materials and Methods: To evaluate the effects of NC-1 on the CSCs in SW620, human colon cancer cells, the enzymatic activity of aldehyde dehydrogenase (ALDH) was analyzed by flow cytometry using an Aldefluor assay. The expression of CSCs surface marker protein, CD133, was analyzed using flow cytometry. Antitumor efficacy of NC-1 was evaluated in a human colorectal tumor xenograft mouse model. Results: We demonstrated that treatment of cancer cells with NC-1 significantly downregulated ALDH positive cell population in a dose-dependent manner. In addition, NC-1 suppressed cell surface expression of CD133 in a dose-dependent manner, suggesting that NC-1 preferentially killed CSCs population in vitro. Furthermore, NC-1 inhibited tumor growth in the HCT116 xenograft mouse model. Citation Format: Yuko Uno, Hideki Moriyama, Shigeki Kashimoto, Mari Masuda, Masaaki Sawa, Tesshi Yamada. A novel TNIK inhibitor potently downregulates cancer stem cell population through attenuation of Wnt signaling [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B146.