Preparation of liposomes co-encapsulating doxorubicin and mifepristone for treating multidrug-resistant cancer

The emergence of multidrug resistance (MDR) is well-known to decrease the therapeutic effects of anticancer drugs. To increase anticancer drug efficacy and decrease adverse effects, we prepared liposomes co-encapsulating doxorubicin (DXR) and mifepristone (MIF) (DXR/MIF-LPs) for treating MDR cancer and evaluated the MDR reversal effect in DXR-resistant Colon-26 cancer cells (C26/DXR). Liposomal encapsulation was performed using remote loading methods: amphipathic DXR was encapsulated using the ammonium sulfate gradient method, whereas hydrophobic MIF was encapsulated in preformed liposomes by incubating with water-miscible dimethyl sulfoxide. Both drugs were successfully encapsulated in liposomes by simultaneously incubating with blank liposomes without remarkably altering the particle size. The release of each drug from DXR/MIF-LPs corresponded to that from liposomes encapsulating a single drug, indicating that drug encapsulation did not influence drug release. Treatment with MIF did not impact the overexpression of P-glycoprotein (P-gp) in C26/DXR cells. However, DXR/MIF-LPs increased the cellular association of DXR and enhanced cytotoxicity compared with liposomes encapsulating DXR against C26/DXR cells, indicating that MIF inhibits P-gp function and increases the cytotoxicity of DXR in MDR cells. Collectively, our findings suggest that the co-delivery of DXR and MIF using a liposomal formulation is a promising approach for reversing MDR.