Discovery Of Novel Small Molecule Inhibitors Of Wnt Signaling Through In Silico Molecular Docking

Canonical Wnt signaling is one of the crucial pathways involved in embryonic development and tissue homeostasis. However this pathway is often dysregulated in cancers and thus developing effective inhibitors of Wnt signaling is of great interest in the field. Our strategy for inhibition of Wnt signaling involves disruption of the β-catenin (β-cat)-Tcf4 protein-protein interaction (PPI) complex, which is the key effector for nuclear Wnt signaling activity. Towards this goal, we developed a computational model of β-cat for predicting small molecule binders. Application of our computational model to an in silico screen against a library of more than 10,000 compounds predicted 27 compounds as good binders to β-cat. Through in vitro validation experiments such as Wnt reporter assays, co-immunoprecipitation, and surface plasmon resonance (SPR) studies, we identified compound GB1874 as our most promising candidate for inhibiting the β-cat-Tcf4 PPI. Compound GB1874 also affected the proliferation of Wnt-addicted colorectal cancer (CRC) cells in vitro and in tumor xenograft models in vivo. Notably the in vivo efficacy was associated with minimal systemic toxicity. In summary, we report the identification of a novel disruptor of β-cat-Tcf4 interaction, GB1874, which can serve as a promising small molecule candidate for a Wnt signaling inhibitor. Moreover, our study demonstrates the feasibility of using computational modeling to identify new inhibitors of PPI. Citation Format: Joo-Leng Low, Weina Du, Tenzin Gocha, Oguz Gokce, Xiaoqian Zhang, Daniel G. Yim, Adaikalavan Ramasamy, Hao Fan, Ramanuj DasGupta. Discovery of novel small molecule inhibitors of Wnt signaling through in silico molecular docking [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 509.