α-Helix-Mimicking Sulfono-γ-AApeptide Inhibitors for p53–MDM2/MDMX Protein–Protein Interactions

Abstract

The use of peptidomimetic scaffolds is a promising strategy for the inhibition of protein–protein interactions (PPIs). Herein, we demonstrate that sulfono-γ-AApeptides can be rationally designed to mimic the p53 α-helix and inhibit p53–MDM2 PPIs. The best inhibitor, with K d and IC50 values of 26 nM and 0.891 μM toward MDM2, respectively, is among the most potent unnatural peptidomimetic inhibitors disrupting the p53–MDM2/MDMX interaction. Using fluorescence polarization assays, circular dichroism, nuclear magnetic resonance spectroscopy, and computational simulations, we demonstrate that sulfono-γ-AApeptides adopt helical structures resembling p53 and competitively inhibit the p53–MDM2 interaction by binding to the hydrophobic cleft of MDM2. Intriguingly, the stapled sulfono-γ-AApeptides showed promising cellular activity by enhancing p53 transcriptional activity and inducing expression of MDM2 and p21. Moreover, sulfono-γ-AApeptides exhibited remarkable resistance to proteolysis, augmenting their biological potential. Our results suggest that sulfono-γ-AApeptides are a new class of unnatural helical foldamers that disrupt PPIs.

The role of miRNAs in MDMX‐p53 interplay

“…have been developed and shown anticancer activity in vitro and in vivo. 16,47,[80][81][82][83][84][85][86] However, none of these inhibitors has been approved for clinical treatment. 7,87 Almost all of these inhibitors have been designed to reactivate wild-type p53 by inhibiting MDM2 and/or MDMX, and it is speculated that these inhibitors may have little or no inhibitory effect on human cancer cells with p53 mutation or p53 deletion.…”

“…Dozens of MDMX inhibitors and MDMX/MDM2 dual inhibitors have been developed and shown anticancer activity in vitro and in vivo 16,47,80–86 . However, none of these inhibitors has been approved for clinical treatment 7,87 .…”

The activity of sulfono-γ-AApeptide helical foldamers that mimic GLP-1

“…Circular dichroism CD spectra were measured on an Aviv 215 CD spectrometer using a 1-mm path length quartz cuvette, and compound solutions in PBS buffer were prepared using dry weight of the lyophilized solid followed by dilution to give the desired concentration (100 M) and solvent combination (23,24). Ten scans were averaged for each sample, three times of independent experiments were conducted, and the spectra were averaged.…”

“…Sulfono--AApeptides are recently introduced as a new class of helical mimetics to address some enduring challenges in disrupting -helix-mediated protein-protein interactions (20)(21)(22)(23)(24)(25)(26)(27). As proteolytically stable peptidomimetics, sulfono--AApeptides exhibit unusual folding stability by adopting a series of helical structures with well-defined hydrogen bonding patterns (21).…”

“…Furthermore, the single crystal of the homogeneous sulfono--AA foldamers reveals a precise three-dimensional (3D) arrangement of their side functional groups and the helical pitch (5.1 versus 5.4 Å of -helix) (21), leading to helical mimetics for targeting various -helix-interacting proteins (Fig. 1, B and C) (23,24). We were intrigued whether this -helix-mimicking strategy could be used to mimic GLP-1, a very long helical peptide.…”