Yoshihiko Hirohashi

Smac13-Tat Fusion Peptide Induces Cell Death and Sensitizes HeLa Cells to Chemotherapeutic Drugs

Background: The inhibitor of apoptosis proteins (IAPs) are overexpressed in a variety of cancer cells and play an important role in the inhibition of caspases, thereby suppressing programed cell death and leading to chemoresistance of cancer cells. However, the anti-apoptotic function of IAPs could be suppressed by Smac, the second mitochondria-derived activator of caspase through its direct interaction with IAPs. Smac can interact with IAPs through the N-terminal Ala-Val-Pro-Ile tetrapeptide domain. Methods: In the present study, the first 7 amino acid sequence (residues 54-60), Smac7,and the first 13 amino acid sequence (residues 54-66), Smac13, which are conserved among mammalian homologues were transduced into cells by bonding to the HIV-1 Tat-derived cell-penetrating peptide. Results: The Smac-Tat peptides induced cell death and increased the sensitivity to chemotherapeutic agents in HeLa cells, whereas they did not affect cell survival in normal lymphocytes. The Smac7Tat peptide could bind to Livin but not Survivin. Conclusion: We demonstrate here that Smac13-Tat is more effective for chemosensitization than Smac7-Tat and that its use might serve as a potent molecular targeted therapy for chemoresistant cervical cancer.