Designed synthetic analogs of the α-helical peptide temporin-La with improved antitumor efficacies via charge modification and incorporation of the integrin αvβ3 homing domain.

How to target cancer cells with high specificity and kill cancer cells with high efficiency remains an urgent demand for anticancer drugs. Temporin-La, which belongs to the family of temporins, presents antitumor activity against many cancer cell lines. We first used a whole bioinformatic analysis method as a platform to identify new anticancer antimicrobial peptides (AMPs). On the basis of these results, we designed a temporin-La analog (temporin-Las) and related constructs containing the Arg-Gly-Asp (RGD) tripeptide, the integrin αvβ3 homing domain (RGD-La and RGD-Las). We detected a link between the net charges and integrin αvβ3 expression of cancer cell lines and the antitumor activities of these peptides. Temporin-La and its synthetic analogs inhibited cancer cell proliferation in a dose-dependent manner. Evidence was provided that the affinity between RGD-Las and tumor cell membranes was stronger than other tested peptides using a pull-down assay. Morphological changes on the cell membrane induced by temporin-La and RDG-Las, respectively, were examined by scanning electron microscopy. Additionally, time-dependent morphological changes were detected by confocal microscopy, where the binding process of RGD-Las to the cell membrane could be monitored. The results indicate that the electrostatic interaction between these cationic peptides and the anionic cell membrane is a major determinant of selective cell killing. Thus, the RGD tripeptide is a valuable ligand motif for tumor targeting, which leads to an increased anticancer efficiency by RGD-Las. These AMP-derived peptides have clinical potential as specifically targeting agents for the treatment of αvβ3 positive tumors.