Sorafenib-Loaded PLGA-TPGS Nanosystems Enhance Hepatocellular Carcinoma Therapy Through Reversing P-Glycoprotein-Mediated Multidrug Resistance.

Multidrug resistance (MDR) is a key determinant for hepatocellular carcinoma chemotherapy failure. P-glycoprotein is one of the main causes of MDR by causing drug efflux in tumor cells. In order to solve this thorny problem, we prepared a sorafenib-loaded polylactic acid-glycolic acid (PLGA) - D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) nanoparticles (SPTNs). SPTNs were successfully synthesized through an ultrasonic emulsion solvent evaporation method with a favourable encapsulation efficiency of 90.35%. SPTNs were almost spherical in shape with uniform particle size (215.70 ± 0.36 nm), narrow polydispersity index (0.27 ± 0.02) and negative surface charge (-26.01 ± 0.65 mV). In the cellular uptake assay, the intracellular coumarin-6 (C6) fluorescence of TPGS component-based PLGA nanoparticles (C6-PTNs) was 1.63-fold higher relative to that of PVA component-based PLGA nanoparticles (C6-PVNs). The half-maximal inhibitory concentration and apoptosis ratio of SPTNs against HepG2/MDR cells were 3.90 μM and 75.62%, respectively, which were notably higher than free SF and sorafenib-PLGA-PVA nanoparticles (SPVNs). The anti-drug efflux activities of SPTNs were assessed by the intracellular trafficking assay using verapamil as a P-gp inhibitor. SPTNs could effectively inhibit the drug efflux in tumor cells detected by flow cytometry, and suppressed relative MDR1 gene as well as P-glycoprotein expression in tumor cells. Attributed to the MDR reversion effect of SPTNs, the in vivo antitumor efficacy experiment showed that SPTNs significantly inhibited the tumor growth of HepG2/MDR xenograft-bearing nude mice, and obviously reduced the toxicity against liver and kidney compared with SF treatment. In summary, SPTNs, as highly efficient and safe antitumor nano delivery systems, showed promising potential for hepatocellular carcinoma therapy through reversing P-glycoprotein-mediated MDR. Graphical Abstract.