Small-molecule inhibition of Wnt signaling through activation of casein kinase 1α

Area of Science:

• Molecular Biology
• Cell Signaling
• Drug Discovery

Background:

• Wnt/β-catenin signaling is crucial for development, stem cell function, and disease pathogenesis.
• Dysregulation of this pathway is implicated in various human diseases, particularly cancer.

Purpose of the Study:

• To identify novel inhibitors of Wnt/β-catenin signaling.
• To explore the therapeutic potential of identified compounds against Wnt pathway-driven cancers.

Main Methods:

• Screening of compounds using Xenopus laevis egg extract to identify modulators of Axin stabilization and β-catenin turnover.
• In vitro binding assays to assess compound interaction with casein kinase 1 (CK1) family members.
• Gene knockdown experiments to validate target engagement (CK1α).
• Cell-based assays using colon cancer cell lines to evaluate inhibition of Wnt signaling and proliferation.

Main Results:

• Pyrvinium was identified as a potent Wnt signaling inhibitor with an EC(50) of approximately 10 nM.
• Pyrvinium binds to all CK1 family members and selectively enhances CK1α kinase activity.
• CK1α knockdown reversed the inhibitory effects of pyrvinium on the Wnt pathway.
• Pyrvinium treatment reduced Axin and β-catenin levels, promoted Pygopus degradation, and inhibited proliferation in colon cancer cells.

Conclusions:

• Allosteric activation of CK1α is an effective strategy for inhibiting Wnt signaling.
• Pyrvinium represents a promising therapeutic agent for targeting the Wnt pathway in cancer.
• This study highlights a novel mechanism for Wnt pathway modulation with potential clinical applications.