title: Cell-specific and nuclear targeting with [M(CO)(3)](+) (M=(99m)Tc, Re)-based complexes conjugated to acridine orange and bombesin.
abstract: Receptor-specific nuclear targeting requires trifunctional metal complexes. We have synthesized [M(L(2)-pept)(L(1)-acr)(CO)(3)] (pept=peptide; acr=acridine-based agent) in which the fac-[M(CO)(3)](+) moiety (1st function, M=(99m)Tc, Re) couples an acridine-based nuclear-targeting agent (2nd function, L(1)-acr) and the specific cell-receptor-binding peptide bombesin (3rd function, L(2)-pept). The metal-mediated coupling is based on the mixed ligand [2+1] principle. The nuclear targeting agents have been derivatised with an isocyanide group for monodentate (L(1)) and bombesin (BBN) with a bidentate ligand (L(2)) for complexation to fac-[M(CO)(3)](+). For nuclear uptake studies, the model complexes [Re(L(2))(L(1)-acr)(CO)(3)] (L(2)=pyridine-2-carboxylic acid and pyridine-2,4-dicarboxylic acid) were synthesized and structurally characterized. We selected acridine derivatives as nuclear-targeting agents, because they are very good nucleus-staining agents and exhibit strong fluorescence. Despite the bulky metal complexes attached to acridine, all [Re(L(2))(L(1)-acr)(CO)(3)] showed high accumulation in the nuclei of PC3 and B16F1 cells, as evidenced by fluorescence microscopy. For radiopharmaceutical purposes, the (99m)Tc analogues have been prepared and radioactivity distribution confirmed the fluorescence results. Coupling of BBN to L(2) gave the receptor-selective complexes [M(L(2)-BBN)(L(1)-acr)(CO)(3)]. Whereas no internalization was found with B16F1 cells, fluorescence microscopy on PC3 cells bearing the BBN receptor showed high and rapid uptake by receptor-mediated endocytosis into the cytoplasm, but not into the nucleus.
authors: Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors: Nikos
authors: N
authors: Agorastos
authors: Lubor
authors: L
authors: Borsig
authors: Anabelle
authors: A
authors: Renard
authors: Philipp
authors: P
authors: Antoni
authors: Giampietro
authors: G
authors: Viola
authors: Bernhard
authors: B
authors: Spingler
authors: Philipp
authors: P
authors: Kurz
authors: Roger
authors: R
authors: Alberto
mesh_terms: D000165:Acridine Orange / Q000737:chemistry*; D001839:Bombesin / Q000737:chemistry*; D002467:Cell Nucleus / Q000187:drug effects*; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D012211:Rhenium / Q000737:chemistry / Q000494:pharmacology*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D006639:Histidine; D012211:Rhenium; D000165:Acridine Orange; D003545:Cysteine; D001839:Bombesin