Targeted β‐catenin ubiquitination and degradation by multifunctional stapled peptides

• Published in: Journal of peptide science Vol. 28; no. 7; pp. e3389 - n/a
• Main Authors: Wang, Xiaofeng, Dong, Liuli, Cheng, Jiongjia, Verdine, Gregory L., Lin, Aijun, Chu, Qian
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.07.2022
• Subjects: beta Catenin - genetics; beta Catenin - metabolism; Cancer; Catenin; Colorectal carcinoma; Degradation; Drug development; Gene expression; Humans; MDM2 protein; multifunctional stapled peptide; p53 Protein; Peptides; Peptides - metabolism; Proteasomes; Proteins; Signal transduction; Signaling; Ubiquitin; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Ubiquitination; Ubiquitins - genetics; Ubiquitins - metabolism; Wnt protein; Wnt Signaling Pathway; β‐catenin; β-catenin; degradation; multifunctional stapled peptide; Wnt signaling pathway; ubiquitination
• ISSN: 1075-2617; 1099-1387
• DOI: 10.1002/psc.3389

Aberrant activation of the Wnt signaling pathway has been identified in numerous types of cancer. One common feature of oncogenic Wnt regulation involves an increase in the cellular levels of β‐catenin due to interference with its constitutive ubiquitin‐dependent degradation. Targeting β‐catenin has therefore emerged as an appealing approach for the treatment of Wnt‐dependent cancers. Here, we report a strategy that employs multifunctional stapled peptides to recruit an E3 ubiquitin ligase to β‐catenin, thereby rescuing β‐catenin degradation by hijacking the endogenous ubiquitin‐proteasome pathway. Specifically, we designed, synthesized, and evaluated a panel of multifunctional stapled peptides that have a β‐catenin binding moiety (StAx‐35) covalently linked to a second stapled peptide moiety (SAH‐p53‐8), which is capable to interact with the E3 ubiquitin ligase MDM2. We found that in vitro these multifunctional peptides can recruit the MDM2 protein to β‐catenin and induce poly‐ubiquitination on β‐catenin. In cellulo, treatment of the human colorectal cancer cell line SW480 with the multifunctional stapled peptides showed dose‐dependent degradation of endogenous β‐catenin levels. In addition, a luciferase reporter assay showed that the multifunctional stapled peptides can suppress β‐catenin‐mediated gene expression via the Wnt signaling pathway. Therefore, these multifunctional stapled peptides provide a unique research tool for examining the Wnt signaling pathway by targeted knockdown of β‐catenin at the protein level, and may serve as leads for potential drug candidates in the treatment of Wnt‐dependent cancers. Schematic illustration of β‐catenin ubiquitination and degradation by multifunctional stapled Axin (MSA) peptide is shown. The β‐catenin and MDM2 binding moieties in the MSA peptide are highlighted in purple and orange, respectively. The process starts with MDM2 recruitment to β‐catenin, followed by poly‐ubiquitination of β‐catenin protein, which is eventually recognized and degraded by 26S proteasome.