Conclusion
Our findings not only provide a new class of anticancer drug candidates, but also bridge the gap and reduce the physical distance between peptides and PROTACs.
Methods
Herein we developed stapled peptide-based proteolysis-targeting chimeras (SP-PROTACs), that simultaneously exhibited improved cellular uptake and proteolytic stability attributed to the stapled peptides, and efficient target protein degradation promoted by the PROTACs. Based on the PMI peptide with dual specificity for both MDM2 and MDMX, a series of SP-PROTACs were designed.
Results
Among them, the optimized SPMI-HIF2-1 exhibited similar binding affinity with MDM2 and MDMX but obviously higher helical contents, improved proteolytic stability, better cellular permeability, and a better pharmacokinetic profile compared with its linear counterpart. Importantly, SPMI-HIF2-1 could effectively kill cancer cells and inhibit tumor progression in subcutaneous and orthotopic colorectal cancer xenograft models through simultaneously promoting the atypical degradation of both MDM2 and MDMX and durable p53 activation. An FP-based binding assay and structural modeling analysis of the ternary complex suggested that SPMI-HIF2-1 simultaneously bound with the target protein and E3 ligase.