Enhancing the Stability of Tumor Homing LyP-1 Peptide Using Cyclization and Retro Grafting Strategies

Anticancer peptide therapeutics are promising candidates for cancer treatment as they are highly specific to their targets and can have tumor-homing abilities. Several studies have been shown that a nine-residue tumor-homing LyP-1 peptide can be used in anticancer agent development and in tumor imaging studies. However, because it is a small linear peptide, it is very unstable in serum as most of the peptide therapeutics face before they enter to clinical studies. The main aim of this study is to enhance the serum stability of LyP-1 using cyclization and grafting (and/or retro grafting) strategies. Four grafted versions onto sunflower trypsin inhibitor peptide SFTI-1 and a cyclic homodimerized version of LyP-1 were synthesized and tested on MDA-MB-435S cancer (melanoma) cells and HFF-1 normal fibroblast cells in comparison with cisplatin chemotherapeutics. The cyclic homodimer LyP-1 peptide exhibited extraordinary stability in serum. Additionally, the retro grafted peptides have also improved stability that indicates the retro sequence concept provides peptides with higher stability.