Peptide Inhibitors Targeting FOXO4-p53 Interactions and Inducing Senescent Cancer Cell-specific Apoptosis.

Cellular senescence, marked by irreversible cell cycle arrest and senescence-associated secretory phenotype, contributes to aging and cancer recurrence. While chemotherapy can induce senescence in cancer cells, these therapy-induced senescent cells often resist apoptosis and promote tumor recurrence. The nuclear interaction between FOXO4 and p53 is crucial for senescent cell survival. Using NMR spectroscopy, we identified that hydrophobic interactions in the p53 transactivation domain play a key role in FOXO4 forkhead domain binding. Based on this structural information, we designed an optimized peptide inhibitor with reduced negative charges and incorporated a cationic cell-penetrating peptide for enhanced cellular delivery (CPP-CAND). CPP-CAND exhibited high selectivity for senescent cells, effectively disrupting nuclear FOXO4-p53 foci and inducing caspase-dependent apoptosis. Notably, it showed cytotoxicity against senescent cancer cells induced by different chemotherapeutic agents including doxorubicin and cisplatin. With its enhanced selectivity, l-amino acid composition, and shorter length, CPP-CAND represents a promising therapeutic candidate for targeting therapy-induced senescent cancer cells.