Bypassing multidrug resistance in human breast cancer cells with lipid/polymer particle assemblies

Background: Multidrug resistance (MDR) mediated by the overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) transporters, such as P-glycoprotein (P-gp), remains one of the major obstacles to effective cancer chemotherapy. In this study, lipid/particle assemblies named LipoParticles (LNPs), consisting of a dimethyldidodecylammonium bromide (DMAB)-modified poly(lactic-co-glycolic acid) (PLGA) nanoparticle core surrounded by a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) shell, were specially designed for anticancer drugs to bypass MDR in human breast cancer cells that overexpress P-gp. Methods: Doxorubicin (DOX), a chemotherapy drug that is a P-gp substrate, was conjugated to PLGA and encapsulated in the self-assembled LNP structure. Physiochemical properties of the DOX-loaded LNPs were characterized in vitro. Cellular uptake, intracellular accumulation, and cytotoxicity were compared in parental Michigan Cancer Foundation (MCF)-7 cells and P-gp-overexpressing, resistant MCF-7/adriamycin (MCF-7/ADR) cells. Results: This study found that the DOX formulated in LNPs showed a significantly increased accumulation in the nuclei of drug-resistant cells relative to the free drug, indicating that LNPs could alter intracellular traffic and bypass drug efflux. The cytotoxicity of DOX loaded-LNPs had a 30-fold lower half maximal inhibitory concentration (IC50) value than free DOX in MCF-7/ADR, measured by the colorimetric cell viability (MTT) assay, correlated with the strong nuclear retention of the drug. Conclusion: The results show that this core-shell lipid/particle structure could be a promising strategy to bypass MDR.