title: Delivering aminopyridine ligands into cancer cells through conjugation to the cell-penetrating peptide BP16.
abstract: Peptide conjugates incorporating the N-based ligands (Me2)PyTACN or (S,S')-BPBP at the N- or the C-terminus of the cell-penetrating peptide were synthesized (PyTACN-BP16 (), BP16-PyTACN (), BPBP-BP16 (), and BP16-BPBP ()). Metal binding peptides bearing at the N-terminus the ligand, an additional Lys and a β-Ala were also prepared (PyTACN-βAK-BP16 () and BPBP-βAK-BP16 ()). Moreover, taking into account the clathrin-dependent endocytic mechanism of , the enzymatic cleavable tetrapeptide Gly-Phe-Leu-Gly was incorporated between the ligand and the N- or C-terminus of (BPBP-GFLG-BP16 () and BP16-GLFG-BPBP ()). Analysis of the cytotoxicity of all the peptide conjugates showed that: (i) the position of the ligand influenced the IC50 values, (ii) the incorporation of the βAla-Lys dipeptide rendered non active sequences, (iii) peptide conjugates derived from the (S,S')-BPBP ligand were more active than those bearing (Me2)PyTACN, and (iv) the introduction of the cleavable tetrapeptide significantly enhanced the activity of the BPBP conjugates (IC50 of 4.3 to 11.7 μM ( and ) compared to 26.0 to >50 μM (, and )). The most active peptide was BPBP-GFLG-BP16 () (IC50 of 4.3 to 5.0 μM). This high activity was attributed to its high internalization in MCF-7 cells, as shown by flow cytometry, and to the subsequent release of the ligand by the intracellular cleavage of the enzyme-labile spacer, as observed in cathepsin B enzymatic assays. Therefore, these results pave the way for the design of novel peptide conjugates to be used in pro-oxidant anticancer therapies.
authors.affiliation: QBIS-CAT Research Group, Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. xavi.ribas@udg.edu miquel.costas@udg.edu and LIPPSO, Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. lidia.feliu@udg.edu marta.planas@udg.edu.
authors.forename: M
authors.initials: M
authors.lastname: Soler
authors.affiliation: QBIS-CAT Research Group, Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. xavi.ribas@udg.edu miquel.costas@udg.edu and Departament de Biologia, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. anna.massaguer@udg.edu.
authors.forename: M
authors.initials: M
authors.lastname: González-Bártulos
authors.affiliation: LIPPSO, Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. lidia.feliu@udg.edu marta.planas@udg.edu.
authors.forename: E
authors.initials: E
authors.lastname: Figueras
authors.affiliation: Departament de Biologia, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. anna.massaguer@udg.edu.
authors.forename: A
authors.initials: A
authors.lastname: Massaguer
authors.affiliation: LIPPSO, Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. lidia.feliu@udg.edu marta.planas@udg.edu.
authors.forename: L
authors.initials: L
authors.lastname: Feliu
authors.affiliation: LIPPSO, Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. lidia.feliu@udg.edu marta.planas@udg.edu.
authors.forename: M
authors.initials: M
authors.lastname: Planas
authors.affiliation: QBIS-CAT Research Group, Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. xavi.ribas@udg.edu miquel.costas@udg.edu.
authors.forename: X
authors.initials: X
authors.lastname: Ribas
authors.affiliation: QBIS-CAT Research Group, Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. xavi.ribas@udg.edu miquel.costas@udg.edu.
authors.forename: M
authors.initials: M
authors.lastname: Costas
mesh_terms: D000631:Aminopyridines / Q000737:chemistry / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D057846:Cell-Penetrating Peptides / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D000631:Aminopyridines; D000970:Antineoplastic Agents; D057846:Cell-Penetrating Peptides; D008024:Ligands; D009942:Organometallic Compounds