(518.8) Metallated Anticancer Peptides: An Expanded Mechanism that Encompasses Physical and Chemical Bilayer Disruption

Poster Board Number: A434

Ella Mihailescu (Institute for Bioscience and Biotechnology Research), Fatih Comert (Institute for Bioscience and Biotechnology Research), Frank Heinrich (National Institute of Standards and Technology), Ananda Chowdhury (Institute for Bioscience and Biotechnology Research), Mason Schoeneck (University of Rochester ), Caitlin Darling (Clemson University), Kyle Anderson (Institute for Bioscience and Biotechnology Research), M. Daben Libardo (University of Connecticut), Alfredo Angeles-Boza (University of Connecticut), Vitalii Silin (Institute for Bioscience and Biotechnology Research), Myriam Cotten (William and Mary)

In the search for novel broad-spectrum therapeutics to fight chronic infections, inflammation, and cancer, host defense peptides (HDPs) have garnered increasing interest. Characterizing their biologically-active conformations and minimum motifs for function represents a requisite step to developing them into efficacious and safe therapeutics. Here, we demonstrate that metallating HDPs is an effective chemical strategy to improve their cytotoxicity on cancer cells. Mechanistically, we find that the metallated peptides not only physically but also chemically damage lipid membranes. Our testing ground features piscidins 1 and 3 (P1/3), two amphipathic, histidine-rich, membrane-interacting, and cell-penetrating HDPs that are α-helical bound to membranes. To investigate their membrane location, permeabilization effects, and lipid-oxidation capability, we employ neutron reflectometry, impedance spectroscopy, neutron diffraction, and UV spectroscopy. While P1-apo is more potent than P3-apo, metallation boosts their cytotoxicities by up to two- and seven-fold, respectively. Remarkably, P3 is particularly effective at inserting its metallated motif in bilayers, causing water crevices in the hydrocarbon region and placing Cu2+ near the double bonds of the acyl chains, as needed to oxidize them. This study points at a new paradigm where metallating HDPs to expand their mechanistic reach could be explored to design more potent peptide-based anticancer therapeutics.

National Science Foundation (MCB-1714164 to M.M and V.S.; MCB-1716608 to M.L.C., and MCB-1715494 to A.M.A.B.)