Development of Glycyl-tRNA Synthetase-derived Peptide for Cancer Therapy

Abstract

Peptide therapeutics is a newly emerging field in cancer therapy. They can be rapidly synthesized and easily modified to fit the drug delivery system needs. Peptides have low toxicity and minimal side effects compared to chemical drugs, which are critical for therapeutic drug development. Glycyl-tRNA synthetase (GRS), a known component of translation, has been previously reported to kill cancer expressing cadherin-6 (CDH-6), also known as K-cadherin, by suppressing ERK signaling and inducing apoptosis. In this study, we analyzed the structure of GRS to determine the active region that binds to CDH6 and critical for cancer cell viability. Only fragment 4 (F4) domain of GRS, 511 to 685 residues, showed binding to CDH6 and induced apoptosis in CDH6-positive cells. Next, we used a protein-protein docking program, HADDOCK (High Ambiguity Driven protein-protein DOCKing), to predict the binding region of F4 to CDH6. Upon this analysis, we predicted single point mutants around N-terminal of F4 would perturb the interface binding. It was shown mutants that lost binding with CDH6 had a decrease in anti-cancer activity against CDH6-positive cancer cells. Double mutants were performed to identify that the region harboring the F535E residue was critical by showing a severe decrease in binding. After confirming the binding domain for GRS and CDH6, a peptide was developed based on these results and analyzed. The peptide showed CDH6 binding and dependent activity in dose-dependent manner through dephosphorylation of ERK signal. Xenograft mouse model showed that peptide suppressed tumor growth only in CDH6-expressing cell line. Our results lead to the discovery of binding site between GRS with CDH6 and the use of GRS peptide for therapeutic drug development against cancer.