Biophysical Characterization of LTX-315 Anticancer Peptide Interactions with Model Membrane Platforms: Effect of Membrane Surface Charge

Abstract

LTX-315 is a clinical-stage, anticancer peptide therapeutic that disrupts cancer cell membranes. Existing mechanistic knowledge about LTX-315 has been obtained from cell-based biological assays, and there is an outstanding need to directly characterize the corresponding membrane-peptide interactions from a biophysical perspective. Herein, we investigated the membrane-disruptive properties of the LTX-315 peptide using three cell-membrane-mimicking membrane platforms on solid supports, namely the supported lipid bilayer, intact vesicle adlayer, and tethered lipid bilayer, in combination with quartz crystal microbalance-dissipation (QCM-D) and electrochemical impedance spectroscopy (EIS) measurements. The results showed that the cationic LTX-315 peptide selectively disrupted negatively charged phospholipid membranes to a greater extent than zwitterionic or positively charged phospholipid membranes, whereby electrostatic interactions were the main factor to influence peptide attachment and membrane curvature was a secondary factor. Of note, the EIS measurements showed that the LTX-315 peptide extensively and irreversibly permeabilized negatively charged, tethered lipid bilayers that contained high phosphatidylserine lipid levels representative of the outer leaflet of cancer cell membranes, while circular dichroism (CD) spectroscopy experiments indicated that the LTX-315 peptide was structureless and the corresponding membrane-disruptive interactions did not involve peptide conformational changes. Dynamic light scattering (DLS) measurements further verified that the LTX-315 peptide selectively caused irreversible disruption of negatively charged lipid vesicles. Together, our findings demonstrate that the LTX-315 peptide preferentially disrupts negatively charged phospholipid membranes in an irreversible manner, which reinforces its potential as an emerging cancer immunotherapy and offers a biophysical framework to guide future peptide engineering efforts.

Study of the Membrane Activity of the Synthetic Peptide ∆M3 Against Extended-Spectrum β-lactamase Escherichia coli Isolates

“…This is the case with indolicidin, a peptide with reported antibacterial activity against a wide range of microorganisms and Gram-positive and Gram-negative bacteria (Ando et al 2010 ), with no secondary structure in solution or during interaction with membranes (Hsu & Yip 2007 ; Ladokhin et al 1999 ). Another recognized peptide LTX-315, known as Oncopore™, a synthetic oncolytic peptide active in several cancer cell lines, has also been shown to be structureless in aqueous solution and model membranes made of 100% PC, 70/30% PC/PS, and 50% v/v TFE by circular dichroism (Koo et al 2022 ). Our previous work with infrared spectroscopy also demonstrated the described outcome using tumoral and non-tumoral model membranes (Klaiss-Luna et al 2023 ).…”

Study of the Membrane Activity of the Synthetic Peptide ∆M3 against Extended-Spectrum β-Lactamase Escherichia coli Isolates

“…The mechanism of action of daptomycin has been widely studied, and it has been demonstrated that, as a cyclic peptide, the structure does not present a helical or b-sheet structure (15,55). LTX-315, known as Oncopore TM , a synthetic oncolytic peptide active in several cancer cell lines, has also been shown to be structureless in aqueous solution and model membranes made of 100% PC, 70/30 % PC/PS, and 50% v/v TFE by circular dichroism (20). Our previous work with infrared spectroscopy also demonstrated the described outcome using tumoral and non-tumoral model membranes (19).…”

Unraveling Membrane-Disruptive Properties of Sodium Lauroyl Lactylate and Its Hydrolytic Products: A QCM-D and EIS Study

“…G m is directly proportional to the tendency of ions to flow through the tethered lipid bilayer, whereas C m is inversely related to membrane thickness [45][46][47]. The tBLM fabricated on the gold electrode was characterized using EIS to confirm its formation according to reference values [48,49], and the measured signals served as a baseline before 2000 µM compounds/mixtures were added to the tBLM platform for 30 min, which preceded a subsequent buffer washing step. Note that the baselines of G m and C m values for tBLM formation were in the acceptable range of <~3 µS and 0.7-1.2 µF/cm 2 , respectively.…”