Development and Characterization of the Shortest Anti-Adhesion Peptide Analogue of B49Mod1

Abstract

Inhibition of cancer cell adhesion is an effective approach to killing adherent cancer cells. B49 and its analog B49Mod1 peptides, derived from the extracellular domain (ECD) of bone marrow stromal antigen 2 (BST-2), display anti-adhesion activity on breast cancer cells. However, the minimal sequence required for this anti-adhesion activity is unknown. Here, we further characterized the anti-adhesion activity of B49Mod1. We show that the anti-adhesion activity of B49Mod1 may require cysteine-linked disulfide bond and that the peptide is susceptible to proteolytic deactivation. Using structure-activity relationship studies, we identified an 18-Mer sequence (B18) as the minimal peptide sequence mediating the anti-adhesion activity of B49Mod1. Atomistic molecular dynamic (MD) simulations reveal that B18 forms a stable complex with the ECD of BST-2 in aqueous solution. MD simulations further reveal that B18 may cause membrane defects that facilitates peptide translocation across the bilayer. Placement of four B18 chains as a transmembrane bundle results in water channel formation, indicating that B18 may impair membrane integrity and form pores. We hereby identify B18 as the minimal peptide sequence required for the anti-adhesion activity of B49Mod1 and provide atomistic insight into the interaction of B18 with BST-2 and the cell membrane.

Development of a Cationic Amphiphilic Helical Peptidomimetic (B18L) As A Novel Anti-Cancer Drug Lead

“…B18 peptide was the result of structure activity relationship (SAR) studies on B49Mod1 [ 2 ]. B18 has a net negative charge of –2 at physiological pH, inhibits cell to cell and cell to extracellular matrix (ECM) adhesion, with subtle polyfunctional cytotoxic effects on cancer cells [ 11 ]. To develop peptides with significant cytotoxicity toward cancer cells, we modified B18 through sequence substitution and created five B18-derived peptidomimetics named B18K, B18KL, B18KA, B18L and B18I ( Table 1 ).…”

“…Since B18L is a derivative of BST-2-based peptides B49B49Mod1 [ 2 ] and B18 [ 11 ], we assessed its interaction with the extracellular domain of BST-2 using two different assays—molecular dynamics (MD) simulation and in vitro binding of B18L with recombinant BST-2 (rBST-2) [ 9 ] based on ultraviolet (UV) absorbance at 230 nm. MD simulation of two chains of B18L (chains a and b) and BST-2 (chains a and b) in 0.15 M KCl neutral aqueous solution were performed for 500 ns.…”

“…Given that transmembrane insertion of the parental B18 revealed the potential for water channel formation [ 11 ], we assessed the effect of B18L on the membrane when transmembrane-inserted. Four monomers chains of B18L were transmembrane inserted into POPC/POPS mixed lipid bilayer and simulated for 1000 ns.…”

“…We have previously described the anti-adhesion activities of the BST-2-based peptides B49/B49Mod1 series [ 2 ] and the first generation analog B18 [ 11 ]. While B18 is effective in inhibiting cancer cell adhesion, the peptide has minor cytotoxic activity against cancer cells [ 11 ]. In this manuscript, we report the structure-activity-directed studies of B18 peptide that led to the development of a series of five B18-derived peptidomimetics—B18K, B18KL, B18KA, B18L, B18I.…”

“…We developed the first (B49 and B49Mod1) [ 2 ] and second (B18) [ 11 ] generations of BST-2-based peptide series with anti-adhesion activities. Although B18 inhibits cancer cell adhesion, it does not effectively kill cancer cells within a 24-h experimental window.…”