Controllable release of self-assembled reduction-sensitive paclitaxel dimer prodrug and tetrandrine nanoparticles promotes synergistic therapy against multidrug-resistant cancer

Multidrug resistance (MDR) is the main reason for chemotherapy failure. Nanocarriers combined delivery of anti-cancer drugs and MDR inhibitors is an effective strategy to avoid MDR and improve the anti-cancer activity of drugs. Two paclitaxel (PTX) molecules are linked by disulfide bonds into PTX2. Then, the PTX2 and tetrandrine (TET) are coated together by mPEG-PLGA self-assembled NPs for combinational treatment. Microstructure, physiological stability, and cytotoxicity are characterized for the co-loaded NPs. The NPs exhibit excellent suitability and blood safety for intravenous injection, specifically responsive to pH 6–7, and promptly initiate chemical degradation. Ex vivo fluorescence microscopy image studies indicate that co-loaded NPs increase drug penetration into cancer cells compared with free drugs. MTT assay demonstrates that co-loaded NPs have higher cytotoxicity against HeLa and the flow cytometric analysis shows that co-loaded NPs trigger more apoptosis than the free drugs. Reactive oxygen species (ROS) assay indicates that the drug-loaded NPs generated higher levels of ROS to accelerate apoptosis in HeLa cells. TET can get desirable effects of inhibiting the MDR in advance by binding with the active site on P-gp, then the disulfide bond of PTX2 is broken by glutathione (GSH) in cancer cells and decomposed into PTX to inhibit cancer cell proliferation. Our studies indicate that the co-loaded NPs can potentially overcome the MDR of conventional chemotherapeutic agents.