Enhanced in vitro antiproliferative effects of EpCAM antibody-functionalized paclitaxel-loaded PLGA nanoparticles in retinoblastoma cells

BACKGROUND To specifically deliver paclitaxel (PTX) to retinoblastoma (RB) cells, the anionic surface-charged poly(lactic-co-glycolic acid) (PLGA) NPs loaded with paclitaxel were conjugated with epithelial cell adhesion molecule (EpCAM) antibody for enhancing site-specific intracellular delivery of paclitaxel against EpCAM overexpressing RB cells. METHODS PTX-loaded PLGA NPs were prepared by the oil-in-water single emulsion solvent evaporation method, and the PTX content in NPs was estimated by the reverse phase isocratic mode of high performance liquid chromatography. Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide chemistry was employed for the covalent attachment of monoclonal EpCAM antibody onto the NP surface. In vitro cytotoxicity of native PTX, unconjugated PTX-loaded NPs (PTX-NPs), and EpCAM antibody-conjugated PTX-loaded nanoparticles (PTX-NP-EpCAM) were evaluated on a Y79 RB cell line by a dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, while cellular apoptosis, cysteinyl-aspartic acid protease (caspase)-3 activation, Poly (adenosine diphosphate-ribose) polymerase (PARP) cleavage, and cell-cycle arrest were quantified by flow cytometry. By employing flow cytometry and fluorescence image analyses, the extent of cellular uptake was comparatively evaluated. RESULTS PTX-NP-EpCAM had superior antiproliferation activity, increased arrested cell population at the G(2)-M phase, and increased activation of caspase-3, followed by PARP cleavage in parallel with the induction of apoptosis. Increased uptake of PTX-Np-EpCAM by the cells suggests that they were mainly taken up through EpCAM mediated endocytosis. CONCLUSIONS EpCAM antibody-functionalized biodegradable NPs for tumor-selective drug delivery and overcoming drug resistance could be an efficient therapeutic strategy for retinoblastoma treatment.