A Zebrafish Chemical Suppressor Screening Identifies Small Molecule Inhibitors of the Wnt/β-catenin Pathway

Genetic screening for suppressor mutants has been successfully used to identify important signaling regulators. Using an analogy to genetic suppressor screening, we developed a chemical suppressor screening method to identify inhibitors of the Wnt/beta-catenin signaling pathway. We used zebrafish embryos in which chemically induced beta-catenin accumulation led to an "eyeless" phenotype and conducted a pilot screening for compounds that restored eye development. This approach allowed us to identify geranylgeranyltransferase inhibitor 286 (GGTI-286), a geranylgeranyltransferase (GGTase) inhibitor. Our follow-up studies showed that GGTI-286 reduces nuclear localization of beta-catenin and transcription dependent on beta-catenin/T cell factor in mammalian cells. In addition to pharmacological inhibition, GGTase gene knockdown also attenuates the nuclear function of beta-catenin. Overall, we validate our chemical suppressor screening as a method for identifying Wnt/beta-catenin pathway inhibitors and implicate GGTase as a potential therapeutic target for Wnt-activated cancers.