Discovery of chemical probes that suppress Wnt/β-catenin signaling through high-throughput screening

Abstract

Aberrant activation of the Wnt/β-catenin signaling pathway has been observed in a wide range of human tumors. Deregulation of the pathway is closely linked to various aspects of human carcinogenesis such as cell viability, regulation of cell cycle, epithelial-mesenchymal transition, and maintenance of stemness. In addition, recent studies have disclosed the involvement of Wnt signaling in immune evasion of tumor cells. The accumulation of β-catenin in the nucleus is a common feature of cancer cells carrying defects in the pathway, which leads to the continuous activation of T-cell factor (TCF)/LEF transcription factors. Consequently, a genetic program is switched on, leading to the uncontrolled growth, prolonged survival, and acquisition of mesenchymal phenotype. As β-catenin/TCF serves as a signaling hub for the pathway, β-catenin/TCF-dependent transcriptional activity is a relevant readout of the pathway. To date, a wide variety of synthetic TCF/LEF reporters has been developed, and high-throughput screening (HTS) using these reporters has made significant contributions to the discovery of Wnt inhibitors. Indeed, HTS led to the identification of chemical probes targeting porcupine, a membrane bound O-acyltransferase, and CREB-binding protein, a transcriptional coactivator. This review focuses on various screening strategies for the discovery of Wnt inhibitors and their mode of action to help the creation of new concepts for assay/screening methods.

Keywords: TCF/LEF transcription factor; Wnt/β-catenin signaling pathway; chemical probe; high-throughput screening; reporter assay.