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De-risking Drug Discovery of Intracellular Targeting Peptides: Screening Strategies to Eliminate False-Positive Hits

2020; American Chemical Society; Volume: 11; Issue: 10 Linguagem: Inglês

10.1021/acsmedchemlett.0c00022

1948-5875

Simon Ng, Yu‐Chi Juang, Arun Chandramohan, Hung Yi Kristal Kaan, Ahmad Sadruddin, Tsz Ying Yuen, Fernando J. Ferrer‐Gago, Xue’Er Cheryl Lee, Xi Liew, Charles W. Johannes, Christopher J. Brown, Srinivasaraghavan Kannan, Pietro G. A. Aronica, Nils Berglund, Chandra Verma, Lijuan Liu, Alexander Stoeck, Tomi K. Sawyer, Anthony W. Partridge, David P. Lane,

Biochemical and Structural Characterization

Nonspecific promiscuous compounds can mislead researchers and waste significant resources. This phenomenon, though well-documented for small molecules, has not been widely explored for the peptide modality. Here we demonstrate that two purported peptide-based KRas inhibitors, SAH-SOS1A and cyclorasin 9A5, exemplify false-positive molecules—in terms of both their binding affinities and cellular activities. Through multiple gold-standard biophysical techniques, we unambiguously show that both peptides lack specific binding to KRas and instead induce protein unfolding. Although these peptides inhibited cellular proliferation, the activities appeared to be off-target on the basis of a counterscreen with KRas-independent cell lines. We further demonstrate that their cellular activities are derived from membrane disruption. Accordingly, we propose that to de-risk false-positive molecules, orthogonal binding assays and cellular counterscreens are indispensable.