title: Design and synthesis of a multivalent fluorescent folate-calix[4]arene conjugate: cancer cell penetration and intracellular localization.
abstract: A novel fluorescently labeled folate conjugate in which four folic acid units are covalently conjugated with a 7-nitro-benzofurazan fluorophore by means of a calix[4]arene platform was synthesized by using a Cu-catalyzed azide-alkyne cycloaddition reaction (click chemistry). The synthesized construct (FA-C4-NBD) was characterized by mass spectrometry, NMR and fluorescence spectroscopy. Confocal fluorescence microscopy experiments were carried out to evaluate the cell penetration ability of FA-C4-NBD on normal and cancer cells. The cellular uptake of FA-C4-NBD proceeds via folate receptor-mediated endocytosis. FA-C4-NBD is internalized into HeLa cancer cells which express high levels of folate receptors, whereas the uptake into fibroblast NIH3T3 cells which have very low expression levels of folate receptors is negligible. The involvement of the folate receptor was corroborated by competition tests with free folic acid. Co-localization analysis with different organelle markers indicated that FA-C4-NBD is not eliminated by recycling towards the outside of the cell, but accumulates intracellularly in the endo-lysosomal system.
authors: Istituto di Chimica Biomolecolare, C.N.R., Via Paolo Gaifami 18, I-95126, Catania, Italy. grazia.consoli@icb.cnr.it.
authors: Grazia Maria Letizia
authors: GM
authors: Consoli
authors: Giuseppe
authors: G
authors: Granata
authors: Giorgia
authors: G
authors: Fragassi
authors: Mauro
authors: M
authors: Grossi
authors: Michele
authors: M
authors: Sallese
authors: Corrada
authors: C
authors: Geraci
mesh_terms: D000818:Animals; D047250:Calixarenes / Q000737:chemistry / Q000493:pharmacokinetics*; D045744:Cell Line, Tumor; D015195:Drug Design; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics*; D005492:Folic Acid / Q000737:chemistry / Q000493:pharmacokinetics*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D015394:Molecular Structure; D041681:NIH 3T3 Cells; D009369:Neoplasms / Q000473:pathology*; D010636:Phenols / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D005456:Fluorescent Dyes; D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes; D005492:Folic Acid