Vitamin E-tocopheryl polyethylene glycol succinate decorated drug delivery system with synergistic antitumor effects to reverse drug resistance and immunosuppression

To overcome cancer drug resistance and to reverse tumor immunosuppression, a vitamin E-tocopheryl polyethylene glycol succinate (TPGS) decorated polymer-based drug delivery system was developed. The effects of the drug delivery system on diverse proteins involved in cell apoptosis, cancer invasion, metastasis and immunosuppression were investigated to provides a more comprehensive understanding of TPGS modified drug delivery systems. Curcumin (CUR), a hydrophobic drug, was loaded in star poly(DL-lactide) with a cholic acid core, and then decorated with TPGS shell to obtain CUR@TPGS/star poly(DL-lactide) nanoparticles (CUR@TPNP). Cholic acid cored star poly(DL-lactide) is featured by a rapid degradation rate with a surface erosion characteristic. TPGS not only reverses tumor drug resistance through downregulating P-gp expression of tumor cells but also enhances the anti-tumor efficiency through combined TPGS/CUR therapeutic actions on reversal of tumor immunosuppression mediated by CD47 and PD-L1. As compared with the CUR loaded nanoparticles without TPGS decoration, CUR@TPNP with TPGS decoration results in significantly enhanced intracellular drug accumulation to efficiently induce cell apoptosis in drug resistant tumor cells. More importantly, CUR@TPNP possesses considerably improved efficacy in upregulating p53 and p21 as well as downregulating beta-catenin, MMP-9, Snail, CD47 and PD-L1, indicating the TPGS decorated drug delivery system inhibits tumor development and metastasis much more efficiently.