title: Synthesis, characterization, antitumor activity of pluronic mimicking copolymer micelles conjugated with doxorubicin via acid-cleavable linkage.
abstract: Pluronic mimicking poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer having multiple hydroxyl groups in the PPO middle segment (core-functionalized Pluronic: CF-PLU) was synthesized for conjugation of doxorubicin (DOX). DOX was conjugated on the multiple hydroxyl groups of CF-PLU via an acid-labile hydrazone linkage (CF-PLU-DOX). In aqueous solution, CF-PLU-DOX copolymers self-assembled to form a core/shell-type micelle structure consisting of a hydrophobic DOX-conjugated PPO core and a hydrophilic PEO shell layer. The conjugated DOX from CF-PLU-DOX micelles was released out more rapidly at pH 5 than pH 7.4, indicating that the hydrazone linkage was cleaved under acidic condition. CF-PLU-DOX micelles exhibited greatly enhanced cytotoxicity for MCF-7 human breast cancer cells compared to naked DOX, while CF-PLU copolymer itself showed extremely low cytotoxicity. Flow cytometry analysis revealed that the extent of cellular uptake for CF-PLU-DOX micelles was greater than free DOX. Confocal image analysis also showed that CF-PLU-DOX micelles had a quite different intracellular distribution profile from free DOX. CF-PLU-DOX micelles were mainly distributed in the cytoplasm, endosomal/lysosomal vesicles, and nucleus, while free DOX was localized mainly within the nucleus, suggesting that CF-PLU-DOX micellar formulation might be advantageously used for overcoming the multidrug resistance (MDR) effect, which gradually develops in many tumor cells during repeated drug administration.
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Lee
authors.forename: Sung Young
authors.initials: SY
authors.lastname: Park
authors.forename: Hyejung
authors.initials: H
authors.lastname: Mok
authors.forename: Tae Gwan
authors.initials: TG
authors.lastname: Park
mesh_terms: D000143:Acids / Q000737:chemistry; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000138:chemical synthesis* / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D020442:Poloxamer / Q000138:chemical synthesis* / Q000494:pharmacology*; D012542:Scattering, Radiation
chemical_list: D000143:Acids; D000970:Antineoplastic Agents; D008823:Micelles; D020442:Poloxamer; D004317:Doxorubicin