Peptide inhibitors QTSWGPEM and QPSGGPYM suppress p53-COP1 interaction, reducing p53 ubiquitination

Breast cancer, a leading cause of female mortality, often involves dysregulated p53 protein, a critical tumor suppressor. p53 regulates cell proliferation, DNA repair, and apoptosis, but its function is frequently compromised by ubiquitination mediated by E3 ubiquitin ligases like COP1. Inhibiting the p53-COP1 interaction could prevent p53 degradation, thereby restoring its tumor-suppressive activity and offering a novel therapeutic strategy for breast cancer.

Researchers employed a combined computational and experimental approach to design peptide inhibitors. They began with Molecular Dynamics (MD) simulations and MM-PBSA calculations to precisely map the p53 protein's interaction interface with COP1. Subsequently, peptide ligands were designed to specifically target this COP1-binding region on p53. These candidate peptides underwent docking and further MD simulations for initial screening. The most promising candidates, QTSWGPEM and QPSGGPYM, were then synthesized and validated experimentally.

The designed peptides demonstrated significant inhibitory effects on the p53-COP1 interaction. Both QTSWGPEM and QPSGGPYM were confirmed to bind directly to the p53 protein in both enzyme-linked immunosorbent assay (ELISA) and fluorescence polarization (FP) assay. In competitive ELISA experiments, the peptides effectively suppressed the p53-COP1 interaction, with QTSWGPEM achieving a remarkable inhibition rate of 75% and QPSGGPYM showing 36% inhibition.

The most potent peptide, QTSWGPEM, suppressed the p53-COP1 interaction by 75% in competitive ELISA, indicating a strong potential for restoring p53 function. Further validation through pull-down assay unequivocally confirmed the effective suppression of the p53-COP1 interaction by these designed peptides. These results highlight the successful application of a hybrid computational-experimental strategy for developing targeted protein-protein interaction inhibitors.