Protein-Protein Interaction Inhibitors as Tools in Chemical Biology (#74)
Protein-protein interactions (PPIs) have emerged as promising therapeutic targets that offer new opportunities in the battle against diseases caused by dysregulated transcriptional [1] In this context, peptides represent a promising molecular class to modulate these interactions, due to their high affinity, binding specificity and ability to form secondary structures, which enable them to cover large surfaces. [2] Here I will provide an overview of our work related to peptides and in particular how a peptide can disrupt the heterodimer ELOB/C, which affects cancer cell proliferation.[4] Our peptide inhibitor was designed based on the ELOB/C’s recognition motif, the so-called “BC-box”, which binds with low sub-nanomolar affinity to this heterodimer (Kd = 0.46 ± 0.02 nM). Characterization of the binding topology by hydrogen-deuterium exchange (HDX) and circular dichroism (CD) indicated an induced alpha-helical binding conformation to ELOB/C. For pull-down and cell-based experiments we incorporated a cell-penetrating sequence (R8) and demonstrated not only dose-dependent disruption of ELOB/C interactors (EPOP or the Von-Hippel-Lindau tumour suppressor, VHL), but also significant proliferation impairment of various cancer cell lines (e.g. PC3 cells, wild-type: IC50 = 10.99 ± 2.40 μM, scramble: IC50 = 23.15 ± 2.53 μM). By flow cytometry we confirmed the pronounced induction of early (6.9%) and late apoptotic (15.9%) cells compared to the control peptides (scramble: 1.6% early, 5.3% late). Finally, RNA sequencing analysis on peptide-treated PC3 cells display an altered transcriptome, which included the downregulation of cancer-related pathways. All together, we successfully implemented a designed peptide inhibitor to probe the cellular interactions and transcriptional changes of ELOB/C’s cancer-relevant PPIs. This demonstrates the potential and versatility of peptide-based approaches for the investigation of PPIs and offers a starting point to develop further optimized inhibitors for ELOB/C. [3]
- [1] Lu, H et. Al., Recent advances in the development of protein-protein interactions modulators: mechanisms and clinical trials. Signal Transduction and Targeted Therapy 2020, 5(1), 213. [2] Wang et al., Rational Design of Peptide-Based Inhibitors Disrupting Protein-Protein Interactions. Frontiers in Chemistry 2021, 9, 685675. [3] Fischer, S. and Trinh, V. T. et al. Peptide-mediated inhibition of the transcriptional regulator Elongin BC induces apoptosis in cancer cells, Cell Chemical Biology 2023, 30, 766