A Codelivery System of Anticancer Drug Doxorubicin and Tumor-Suppressor Gene p53 Based on Polyphosphoester for Lung Cancer Therapy

Abstract

In order to obtain nanoparticles loaded with both the anticancer drug doxorubicin (DOX) and p53 gene, a pH-responsive doxorubicin prodrug and polycationic carrier can be respectively prepared through a combination of ring-opening polymerization (ROP) and “click” reaction. First, poly(ethylene glycol)monomethyl ether (mPEG) is used to initiate the ring-opening polymerization of a cyclic phosphoester monomer, 2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane (abbreviated as BYP), resulting in a block copolymer precursor (mPEG-b-PBYP) containing alkynyl groups in the side chain. In another reaction, a pH-responsive doxorubicin derivative (DOX-hyd-N3) containing an azide group and an acid-sensitive hydrazone bond (-hyd-) is synthesized. Subsequently, the polymeric prodrug mPEG-b-PBYP-hyd-DOX is prepared by Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC) “click” reaction between the alkynyl group of mPEG-b-PBYP and the azide group of DOX-hyd-N3. And the polycationic carrier (abbreviated as mPEG-b-PBYP-g-DAE) is obtained via the thiol-yne “click” reaction between mPEG-b-PBYP and 2-dimethylaminoethanethiol hydrochloride (DAE). The structures of mPEG-b-PBYP-hyd-DOX and mPEG-b-PBYP-g-DAE are characterized by magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), ultraviolet-visible spectrophotometer (UV-vis), Fourier transform infrared spectroscopy (FT-IR), and high-performance liquid chromatography (HPLC) analyses. The two kinds of polymers can self-assemble into mixed micelles in aqueous solution, which are then combined with p53 gene by electrostatic interaction to form nanoparticles coencapsulated with the DOX and p53 gene. The size and morphology of the mixed micelles are characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). And the release of DOX from the nanoparticles is studied by fluorescence spectrophotometer. The gene condensation ability of the mixed micelles is tested by zeta potential and gel retardation assay. Furthermore, in vitro cell experiments have proved the biocompatibility of the polymer precursor, the effect of nanoparticles on cancer cell inhibition, and the process of effective release of DOX and p53 gene after the nanoparticle enters the A549 cells by endocytosis. Meanwhile, the gene transfection effect of nanoparticles at different N/P ratios can be observed by confocal laser-scanning microscope. These results demonstrate that the DOX/p53 gene-coloaded nanoparticles have broad application prospects in the treatment of lung cancer.