Engineering a nanostructured nucleolin-binding peptide for intracellular drug delivery in triple-negative breast cancer stem cells

Abstract

Altres ajuts: La Fundació Marató TV3 (TV32013-133930-1-2), AECC post-doctoral fellowship (AIO14142112SERA) i ICREA Academia award

Five peptide ligands of four different cell surface receptors (nucleolin, CXCR1, CMKLR1, and CD44v6) have been evaluated as targeting moieties for triple-negative human breast cancers. Among them, the peptide F3, derived from phage display, promotes the fast and efficient internalization of a genetically fused green fluorescent protein (GFP) inside MDA-MB-231 cancer stem cells in a specific receptor-dependent fashion. The further engineering of this protein into the modular construct F3-RK-GFP-H6 and the subsequent construct F3-RK-PE24-H6 resulted in self-assembling polypeptides that organize as discrete and regular nanoparticles. These materials, 15-20 nm in size, show enhanced nucleolin-dependent cell penetrability. We show that the F3-RK-PE24-H6, based on the Pseudomonas aeruginosa exotoxin A (PE24) as a core functional domain, is highly cytotoxic over target cells. The combination of F3, the cationic peptide (RK), and the toxin domain PE24 in such unusual presentation appears as a promising approach to cell-targeted drug carriers in breast cancers and addresses selective drug delivery in otherwise difficult-to-treat triple-negative breast cancers.