Doxorubicin Delivery Systems with an Acetylacetone-Based Block in Cholesterol-Terminated Copolymers: Diverse Activity Against Estrogen-Dependent and Estrogen-Independent Breast Cancer Cells

The study presents the synthesis of original cholesterol-terminated copolymers comprising acetylacetone-based (AcacI) and N-isopropylacrylamide (NIPAAm) units with a varied arrangement (block and random copolymers). The nanoprecipitation method was used to form empty and doxorubicin-loaded polymeric nanoparticles (PNPs) from these copolymers, which were further studied in terms of their physicochemical and biological properties. Unexpectedly, it was revealed that even empty PNPs are effective against breast cancer cells, specifically towards estrogen-dependent MCF-7 cell line. The anti-cancer efficacy was further improved when a low dose of doxorubicin was introduced to the tested systems. It was shown that the proposed carriers modulate doxorubicin (DOX) compatibility with representatives of normal cells, including immune cells, cardiomyocyte cells, and fibroblasts, and reduce side effects associated with standard chemotherapy. The use of these carriers might be a strategy leading to enhancement of DOX activity in cancer cells which develop resistance through decreased drug penetration or drug efflux.