Self-Assembled Indomethacin Dimer Nanoparticles Loaded with Doxorubicin for Combination Therapy in Resistant Breast Cancer.

An ortho-ester-linked indomethacin (IND) dimer-based nanodrug delivery system was prepared to improve the therapeutic effect of doxorubicin (DOX) by reversing the multidrug resistance. The synthesized dimer (IND-OE) could form stable nanoparticles (IND-OE/DOX) loaded with DOX via the single-emulsion method. Compare to insensitive nanoparticles (IND-C12/DOX), IND-OE/DOX showed a rapid degradation behavior and accelerated drug release at mildly acidic environments. In vitro cell experiments verified that IND-OE nanoparticles could increase DOX concentration due to the efficient intracellular drug release by the degradation of the ortho ester as well as reduced DOX efflux by IND-mediated P-gp downregulation. In vivo studies further demonstrated that IND-OE/DOX displayed the maximized synergetic antitumor efficacy than free DOX or IND-C12/DOX, and the tumor inhibition rates versus saline were 46.78% (free DOX), 60.23% (IND-C12/DOX), and 80.62% (IND-OE/DOX). Overall, this strategy of combination with chemosensitizers and ortho ester linkage has great potential to serve as an amplifying chemotherapy platform against various drug-resistant tumors.