Pep5-based antitumor peptides containing multifunctional fragments with enhanced activity and synergistic effect

In this study, we designed a series of hybrid peptides based on pep5-TAT (P-05), comprising antitumor segment (pep5), endosomal escape segment ((LLHH)₃) and cell penetrating/membrane disrupting segment (TAT, R₉, sC18₂). These peptides exhibited remarkable antitumor activity towards tumor cells (HepG2, A549). Among them, the IC₅₀ values of peptide P-09 were 4.0 and 4.8 times lower than those of P-05 in HepG2 and A549 cells, respectively. It was proved that P-09 could enter tumor cells through endocytosis and direct penetration and induce the apoptosis and necrosis. The antitumor effects were attributed to the synergistic effect of membrane disruption and proteasome inhibition, which occurred during and after the cellular entry, respectively. The whole process was accompanied by excessive ROS production. In vivo, P-09 exhibited enhanced ability to inhibit the growth of HepG2 subcutaneous tumor xenografts than P-05 in nude mice. In brief, this work provided valuable insights into the design of peptide-based antitumor agents with synergistic antitumor effects.