title: Cathepsin nanofiber substrates as potential agents for targeted drug delivery.
abstract: The development of reactive drug carriers that could actively respond to biological signals is a challenging task. Different peptides can self-assemble into biocompatible nanostructures of various functionalities, including drugs carriers. Minimal building blocks, such as diphenylalanine, readily form ordered nanostructures. Here we present the development of self-assembled tetra-peptides that include the diphenylalanine motif, serving as substrates of the cathepsin proteases. This is of great clinical importance as cathepsins, whose activity and expression are highly elevated in cancer and other pathologies, have been shown to serve as efficient enzymes for therapeutic release. Based on the cathepsins affinity around the active site, we generated a library of Phe-Phe-Lys-Phe (FFKF) tetra-peptide substrates (TPSs). We inserted various N-termini capping groups with different chemical properties to investigate the effect on protease affinity and self-assembly. All nine TPSs were cleaved by their targets, cathepsins B and L. However, solvent switching led to nanofibers self-assembly of only seven of them. Due to its rapid self-assembly and complete degradation by cathepsin B, we focused on TPS4, Cbz-FFKF-OH. Degradation of TPS4 nanofibers by cathepsin B led to the release of 91.8±0.3% of the incorporated anti-cancerous drug Doxorubicin from the nanofibers within 8h while only 55±0.2% was released without enzyme treatment. Finally, we demonstrated that tumor lysates fully degraded TPS4 nanofibers. Collectively, these results suggest that tetra-peptide substrates that form nanostructures could serve as a promising platform for targeted drug delivery to pathologies in which protease activity is highly elevated.
authors.affiliation: The Institute for Drug Research, School of Pharmacy, Faculty of Medicine, Hebrew University, Jerusalem, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Ben-Nun
authors.affiliation: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Galit
authors.initials: G
authors.lastname: Fichman
authors.affiliation: Department of Oral Biology, The Goldschleger School of Dental Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Lihi
authors.initials: L
authors.lastname: Adler-Abramovich
authors.affiliation: Department of Biochemistry and Molecular Biology, J. Stefan Institute, Ljubljana, Slovenia; Faculty of Chemistry and Chemical Technology, University of Ljubljana, Slovenia; Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Jamova cesta 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Boris
authors.initials: B
authors.lastname: Turk
authors.affiliation: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; Department of Materials Science and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ehud
authors.initials: E
authors.lastname: Gazit
authors.affiliation: The Institute for Drug Research, School of Pharmacy, Faculty of Medicine, Hebrew University, Jerusalem, Israel. Electronic address: galiabl@ekmd.huji.ac.il.
authors.forename: Galia
authors.initials: G
authors.lastname: Blum
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage; D002403:Cathepsins / Q000378:metabolism*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000008:administration & dosage; D004337:Drug Carriers / Q000737:chemistry / Q000378:metabolism*; D016503:Drug Delivery Systems; D006801:Humans; D057139:Nanofibers / Q000737:chemistry / Q000648:ultrastructure; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D004337:Drug Carriers; D009842:Oligopeptides; C041142:phenylalanyl-phenylalanyl-phenylalanine; D004317:Doxorubicin; D002403:Cathepsins
keywords: Cathepsins; Diphenylalanine; Nanofibers; Self-assembly; Targeted drug delivery