Design and Characterization of Inhibitory Peptides (iPeps) derived from MIEN 1 Protein sequence

Purpose: MIEN1 is a tumor-specific protein that regulates migration and invasion of cancers. It is overexpressed in human breast, prostate, colorectal, ovarian cancers, making this protein a potential therapeutic target for these cancers. Our goal is to identify small inhibitory peptides (iPeps) derived from the native MIEN1 protein. Methods: CASTp server was used to identify the pockets or empty concavities on the MIEN1 protein surface into which potential inhibitory molecules can gain access. Peptide desiging tools like AntiCp , Cancer PPD and Chimera program were utilized. The peptides were the synthesized locally and the ability of the peptides to inhibit proliferation, migration and invasion were assayed. Results: All the peptides designed were cationic and hydrophobic. AntiCP, a support vector machine (SVM)-based web server, showed that the peptides had an SVM threshold of more than 0.5. The peptides were able to form hydrogen bonding with MIEN1 in chimera which is an indication of their MIEN1 binding. AntiCp server also indicated their anticancer activity. Of the 5 peptides tested, three peptides designed based on MIEN 1 protein sequence showed inhibition of MDA-MB-231 cell proliferation in the MTT assay at a concentration of 100 μg/mL. Ongoing experiments will examine the effect of inhibitory peptides on migration and invasion mediated by MIEN 1. Conclusions: Preliminary data demonstrated that peptide sequences potentially blocked MIEN1 functional activities. We will establish these peptides as the first inhibitory molecules of MIEN1 protein and determine their mechanism of action to further develop potent MIEN1 inhibitors