Rationale: Combinations of two or more therapeutic agents targeting different signaling pathways involved in
tumor progression can have synergistic anticancer effects. However,
combination chemotherapies are greatly limited by the different pharmacokinetics,
tumor targeting, and cellular uptake capacities of the combined drugs. We have previously demonstrated the potential synergistic efficacy of
paclitaxel (PTX) and the natural anti-angiogenic agent
tetramethylpyrazine (
TMP) for suppressing ovarian
carcinoma growth. An efficient, facile, and smart nanosystem to deliver PTX and
TMP simultaneously in vivo is greatly desired. Methods: We constructed a redox-sensitive nanosystem based on the amphiphilic PTX-ss-
TMP conjugate, in which PTX and
TMP are linked by a
disulfide bond. We characterized the structure of the drug conjugate by 1H NMR and LC-MS, and then prepared PTX-ss-
TMP NPs by a one-step nanoprecipitation method. We investigated the redox sensitivity,
tumor-targeting ability, anticancer efficacy, and anti-angiogenesis activity of PTX-ss-
TMP NPs in vitro and in vivo. Results: The amphiphilic PTX-ss-
TMP conjugate readily self-assembled into stable nanoparticles in aqueous
solution with a low critical association concentration of 1.35 µg/mL, well-defined spherical structure, small particle size (152 nm), high drug loading, redox-responsive drug release, high biocompatibility, and high storage stability. In
cancer cells pretreated with GSH-OEt, PTX-ss-
TMP NPs exhibited higher cytotoxicity, apoptosis rate, and cell-cycle arrest than monotherapy or combination
therapy with free drugs, which was attributed to their improved cellular uptake and rapid intracellular drug release. Additionally, PTX-ss-
TMP NPs also had a stronger
anti-angiogenesis effect in HUVECs than free drug, which was mediated by VEGFR2-involved downstream signals. Finally, PTX-ss-
TMP NPs showed
tumor-specific accumulation and excellent antitumor activity in A2780 xenograft mice compared with free drug. Conclusions: These in vitro and in vivo results provide clear evidence that this redox-responsive carrier-free nanosystem with intrinsic amphiphilicity has great potential for combination
cancer chemotherapy.