β-Catenin-RAS interaction serves as a molecular switch for RAS degradation via GSK3β

Area of Science:

• Molecular Biology
• Cellular Signaling
• Cancer Research

Background:

• RAS proteins are crucial for cell growth and transformation.
• Glycogen synthase kinase 3 beta (GSK3β) regulates RAS stability via phosphorylation and proteasomal degradation.
• This GSK3β-mediated RAS degradation is impaired in cells with nondegradable mutant (MT) β-catenin.

Purpose of the Study:

• To elucidate the mechanism by which β-catenin affects RAS protein stability.
• To investigate the direct interaction between β-catenin and RAS.
• To explore therapeutic strategies targeting the β-catenin-RAS interaction in colorectal cancer (CRC).

Main Methods:

• Protein-protein interaction studies to identify the binding interface between β-catenin and RAS.
• Analysis of GSK3β phosphorylation sites on RAS.
• Functional assays using peptides to block β-catenin-RAS interaction in CRC cells.
• Investigation of synergistic effects of APC and KRAS mutations in CRC transformation.

Main Results:

• β-catenin directly interacts with RAS at the α-interface, specifically at GSK3β phosphorylation sites (Thr144 and Thr148).
• Degradation of β-catenin is necessary for exposing these sites and enabling RAS degradation.
• A blocking peptide targeting the β-catenin-RAS interaction restored GSK3β-mediated RAS degradation in MT β-catenin CRC cells.
• This interaction modulates the stability of both β-catenin and RAS.

Conclusions:

• The direct interaction between β-catenin and RAS is a key regulatory mechanism for RAS protein stability.
• This interaction provides a molecular link between the Wnt/β-catenin and RAS-ERK pathways.
• Targeting the β-catenin-RAS interaction offers a potential therapeutic strategy for colorectal cancer driven by APC and KRAS mutations.