Rational design of a sensitivity-enhanced tracer for discovering efficient APC-Asef inhibitors.

Zhong, Jie; Guo, Yuegui; Lu, Shaoyong; Song, Kun; Wang, Ying; Feng, Li; Zheng, Zhen; Zhang, Qiufen et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

The adenomatous polyposis coli (APC)-Rho guanine nucleotide exchange factor 4 (Asef) protein-protein interaction (PPI) is essential for colorectal cancer metastasis, making it a promising drug target. Herein, we obtain a sensitivity-enhanced tracer (tracer 7) with a high binding affinity (K<sub>d</sub> = 0.078 μM) and wide signal dynamic range (span = 251 mp). By using tracer 7 in fluorescence-polarization assays for APC-Asef inhibitor screening, we discover a best-in-class inhibitor, MAI-516, with an IC<sub>50</sub> of 0.041 ± 0.004 μM and a conjugated transcriptional transactivating sequence for generating cell-permeable MAIT-516. MAIT-516 inhibits CRC cell migration by specifically hindering the APC-Asef PPI. Furthermore, MAIT-516 exhibits no cytotoxic effects on normal intestinal epithelial cell and colorectal cancer cell growth. Overall, we develop a sensitivity-enhanced tracer for fluorescence polarization assays, which is used for the precise quantification of high-activity APC-Asef inhibitors, thereby providing insight into PPI drug development.

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