Rational Design and Structure Validation of a Novel Peptide Inhibitor of the Adenomatous-Polyposis-Coli (APC)–Rho-Guanine-Nucleotide-Exchange-Factor‑4 (Asef) Interaction

In colorectal cancer, adenomatous
polyposis coli (APC) interacts
with Rho guanine-nucleotide-exchange factor 4 (Asef), thereby stimulating
aberrant colorectal-cancer-cell migration. Consequently, the APC–Asef
interaction represents a promising therapeutic target for mitigating
colorectal-cancer migration. In this study, we adopted the rational-design
strategy involving the introduction of intramolecular hydrogen bonds
and optimization of the lipophilic substituents to improve the binding
affinities of peptides, leading to the discovery of MAI-400, the best
inhibitor of the APC–Asef interaction known to date (Kd = 0.012 μM, IC50 = 0.25 μM).
Comprehensive evaluation of MAI-400 by biochemical and biophysical
assays revealed the formation and effect of an intramolecular hydrogen
bond. A cell-based assay showed MAI-400 efficiently blocking the APC–Asef
interaction in a dose-dependent manner. Therefore, our study provides
a best-in-class inhibitor, MAI-400, based on the rational drug design
and structural validation, that can effectively inhibit the APC–Asef
interaction.