Identification of novel potent peptide inhibitors targeting the polo-box domain of PLK1: structure-based pharmacophore modelling, virtual screening, molecular docking, molecular dynamics study and biological evaluation.

Multiple myeloma, a hematological malignancy, shows PLK1 overexpression in cells correlates with poor prognosis, suggesting PLK1 as a potential therapeutic target. In this study, we discovered five peptides (PLs 1-5) targeting the polo box domain (PBD) of PLK1 through an integrated virtual screening strategy. MST assays confirmed that PLs 1-5 had strong binding affinity for PLK1, especially PL-1 (K_d = 3.11 ± 0.05 nM). Meanwhile, the kinase selectivity assay showed that the PL-1 had no significant inhibitory effects on a panel of other kinases. Molecular dynamics simulation further demonstrated the structural stability of PL-1 and PLK1 complex. Notably, PL-1 displayed potent antiproliferative efficacy against U266 multiple myeloma cells (IC₅₀ = 0.09 ± 0.01 µM). PL-1 showed high intracellular uptake capacity. In addition, PL-1 exhibited good biostability in human serum and liver microsomes. Taken together, PL-1 is a potent and highly selective antitumor agent with considerable therapeutic promise for multiple myeloma.