Enantiomeric CopA3 dimer peptide suppresses cell viability and tumor xenograft growth of human gastric cancer cells

The CopA3 dimer peptide is a coprisin analog that has an anticancer effect against human cancer cells in vitro. In this study, we investigated the anticancer activity of the enantiomeric CopA3 dimer peptide in human gastric cancer cell lines as well as in an in vivo tumor xenograft model. Enantiomeric CopA3 reduced gastric cancer cell viability and exhibited cytotoxicity against cancer cells. Enantiomeric CopA3-induced cell death was mediated by specific interactions with phosphatidylserine and phosphatidylcholine, membrane components that are enriched in cancer cells, in a calcein leakage assay. Moreover, acridine orange/ethidium bromide staining, flow cytometric analysis, and Western blot analysis showed that enantiomeric CopA3 induced apoptotic and necrotic gastric cancer cell death. The antitumor effect was also observed in a mouse tumor xenograft model in which intratumoral inoculation of the peptide resulted in a significant decrease in the SNU-668 gastric cancer tumor volume. In addition, periodic acid-Schiff and hematoxylin staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay revealed apoptotic and necrotic cell death in tumor masses treated with greater than 150 μg CopA3. Collectively, these results indicate that the enantiomeric CopA3 dimer peptide induces apoptosis and necrosis of gastric cancer cells in vitro and in vivo, indicating that the peptide is a potential candidate for the treatment of gastric cancer, which is a common cause of cancer and cancer deaths worldwide.