Co-delivery of epirubicin and paclitaxel using an estrone-targeted PEGylated liposomal nanoparticle for breast cancer

Breast cancer is one of the most frequent malignancies in the female population. Recently, the development of medical products has been advanced for this disease; however, patients still suffer from the failure of current treatments and new therapeutic strategies are urgently required. In this study, due to the overexpression of the estrogen receptor (ER) in breast cancer and the ability of ER to specifically bind to its ligand estrone (ES), an ES-targeted PEGylated epirubicin (EPI) and paclitaxel (PTX) co-loaded liposomal nanoparticle (NP) (termed as ES-SSL-EPI/PTX) was developed. Physicochemical studies demonstrated that the ES-SSL-EPI/PTX had a nanoscaled particle size (similar to 120 nm) and a neutral zeta potential (similar to -5 mV) and presented favorable stability in physiological media. In vitro, the ES-SSL-EPI/PTX showed a significantly higher cellular uptake in human breast cancer MCF-7 cells mainly via the receptor-ligand mediated pathway resulting in effective cytotoxic activity. In vivo targeting study, the accumulation of targeted liposomes in tumor was significantly improved. The systemic circulation time and biodistribution in main organs of EPI and PTX delivered by ES-SSL-Liposomes were increased. Consequently, the ES-SSL-EPI/PTX significantly suppressed tumor growth in the MCF-7-derived tumor-bearing mouse model without inducing toxicity. These results suggested that the ES-SSL-EPI/PTX was a promising formulation for co-delivery of chemotherapeutics in the treatment of breast cancer.