Nanoparticles with Optimal Ratiometric Co-Delivery of Docetaxel with Gambogic Acid for Treatment of Multidrug-Resistant Breast Cancer.

It has been reported that gambogic acid (GA), the main active component of gamboge, could directly inhibit and reduce the expression level of P-gp by promoting protein degradation through post-translational proteasome pathway. In this study, the optimal molar ratio of GA/docetaxel (DTX) that could recover the sensitivity of MCF-7/ADR cells to DTX was firstly investigated. Then GA and DTX were loaded simultaneously in PLGA nanoparticles in terms of the optimal ratio. In vitro cell apoptosis and western-blot assays showed that co-delivery of anticancer drugs resulted in enhanced cell apoptosis through the downregulation of the expression level of P-gp. Interestingly, in vivo pharmacokinetic study demonstrated that GA and DTX are released synchronously in blood from the NPs. Finally, the most effective tumor growth inhibition in the MCF-7/ADR human breast tumor xenograft was observed in the co-delivery nanoparticle formulation group in comparison with saline control, free DTX solution and free DTX/GA solution. Taken together, our study demonstrated that DTX/GA PLGA NPs based combination therapy holds significant potential towards the treatment of multidrug-resistant breast cancer.