Biophysical Survey of Small-Molecule beta-Catenin Inhibitors: A Cautionary Tale

ABSTRACT: The canonical Wingless-related integration site signaling pathway plays a critical role in human physiology, and its dysregulation can lead to an array of diseases. fi-Catenin is a multifunctional protein within this pathway and an attractive yet challenging therapeutic target, most notably in oncology. This has stimulated the search for potent small-molecule inhibitors binding directly to the fi-catenin surface to inhibit its protein???protein interactions and downstream signaling. Here, we provide an account of the claimed (and some putative) small-molecule ligands of ficatenin from the literature. Through in silico analysis, we show that most of these molecules contain promiscuous chemical substructures notorious for interfering with screening assays. Finally, and in line with this analysis, we demonstrate using orthogonal biophysical techniques that none of the examined small molecules bind at the surface of fi-catenin. While shedding doubts on their reported mode of action, this study also reaffirms fi-catenin as a prominent target in drug discovery.