Dithiocarbamate-inspired side chain stapling chemistry for peptide drug design.

Xiang Li,Wang-Xiao He,Marzena Pazgier,W David Tolbert,Hong-Gang Hu,Jia-Can Su,Neelakshi Gohain,Wuyuan Lu,Yan Zou,Weirong Yuan,Fan Niu

doi:10.1039/c8sc03275k

Abstract

Two major pharmacological hurdles severely limit the widespread use of small peptides as therapeutics: poor proteolytic stability and membrane permeability. Importantly, low aqueous solubility also impedes the development of peptides for clinical use. Various elaborate side chain stapling chemistries have been developed for α-helical peptides to circumvent this problem, with considerable success in spite of inevitable limitations. Here we report a novel peptide stapling strategy based on the dithiocarbamate chemistry linking the side chains of residues Lys(i) and Cys(i + 4) of unprotected peptides and apply it to a series of dodecameric peptide antagonists of the p53-inhibitory oncogenic proteins MDM2 and MDMX. Crystallographic studies of peptide-MDM2/MDMX complexes structurally validated the chemoselectivity of the dithiocarbamate staple bridging Lys and Cys at (i, i + 4) positions. One dithiocarbamate-stapled PMI derivative, DTCPMI, showed a 50-fold stronger binding to MDM2 and MDMX than its linear counterpart. Importantly, in contrast to PMI and its linear derivatives, the DTCPMI peptide actively traversed the cell membrane and killed HCT116 tumor cells in vitro by activating the tumor suppressor protein p53. Compared with other known stapling techniques, our solution-based DTC stapling chemistry is simple, cost-effective, regio-specific and environmentally friendly, promising an important new tool for the development of peptide therapeutics with improved pharmacological properties including aqueous solubility, proteolytic stability and membrane permeability.

Highlights

Two major pharmacological hurdles severely limit the widespread use of small peptides as therapeutics: poor proteolytic stability and membrane permeability
We report a novel peptide stapling strategy based on the dithiocarbamate chemistry linking the side chains of residues Lys(i) and Cys(i + 4) of unprotected peptides and apply it to a series of dodecameric peptide antagonists of the p53-inhibitory oncogenic proteins MDM2 and MDMX
The hydrocarbon stapling chemistry takes advantage of Grubbs catalysts to crosslink on resin, via ruthenium-catalyzed ole n metathesis, two unnatural amino acids bearing ole nic side chains at (i, i + 4) or (i, i + 7) positions, and has been successfully used to design various peptide inhibitors with improved proteolytic stability, membrane permeability, and biological activity.[25,26,27,28,29,30,31,32,33,34,35,36]

Summary

Introduction

Two major pharmacological hurdles severely limit the widespread use of small peptides as therapeutics: poor proteolytic stability and membrane permeability. We report a novel peptide stapling strategy based on the dithiocarbamate chemistry linking the side chains of residues Lys(i) and Cys(i + 4) of unprotected peptides and apply it to a series of dodecameric peptide antagonists of the p53-inhibitory oncogenic proteins MDM2 and MDMX.

Results

Conclusion