Hypoxia-ameliorated photothermal manganese dioxide nanoplatform for reversing doxorubicin resistance

Tumor microenvironment-regulated drug delivery system combined with sonodynamic therapy for the synergistic treatment of breast cancer

Co-loading of sonosensitizers and chemotherapeutic drugs into nanocarriers can improve the biocompatibilities, stabilities, and targeting of drugs and reduce the adverse reactions of drugs, providing a robust platform to orchestrate the synergistic interplay between chemotherapy and sonodynamic therapy (SDT) in cancer treatment. In this regard, biodegradable manganese dioxide (MnO2) has attracted widespread attention because of its unique properties in the tumor microenvironment (TME). Accordingly, herein, MnO2 nanoshells with hollow mesoporous structures (H-MnO2) were etched to co-load hematoporphyrin monomethyl ether (HMME) and doxorubicin (DOX), and DOX/HMME-HMnO2@bovine serum albumin (BSA) obtained after simple BSA modification of DOX/HMME-HMnO2 exhibited excellent hydrophilicity and dispersibility. H-MnO2 rapidly degraded in the weakly acidic TME, releasing loaded HMME and DOX, and catalysed the decomposition of H2O2 abundantly present in TME, producing oxygen (O2) in situ, significantly increasing O2 concentration and downregulating the hypoxia-inducible factor 1α (HIF-1α). After irradiation of the tumor area with low-frequency ultrasound, the drug delivery efficiency of DOX/HMME-HMnO2@BSA substantially increased, and the excited HMME generated a large amount of reactive oxygen species (ROS), which caused irreversible damage to tumor cells. Moreover, the cell death rate exceeded 60% after synergistic SDT-chemotherapy. Therefore, the pH-responsive nanoshells designed in this study can realize drug accumulation in tumor regions by responding to TME and augment SDT-chemotherapy potency for breast cancer treatment by improving hypoxia in tumors. Thus, this study provides theoretical support for the development of multifunctional nanocarriers and scientific evidence for further exploration of safer and more efficient breast cancer treatments.

Multifunctional nanoparticles inhibit tumor and tumor-associated macrophages for triple-negative breast cancer therapy

HYPOTHESIS

Tumor-associated macrophages (TAM) are the mainstay of immunosuppressive cells in the tumor microenvironment, and elimination of M2-type macrophages (M2-TAM) is considered as a potential immunotherapy. However, the interaction of breast cancer cells with macrophages hinders the effectiveness of immunotherapy. In order to improve the efficacy of triple-negative breast cancer (TNBC) therapy, strategies that simultaneously target the elimination of M2-TAM and breast cancer cells may be able to achieve a better therapy.

EXPERIMENTS

LyP-SA/AgNP@Dox multifunctional nanoparticles were synthesized by electrostatic adsorption. They were characterized by particle size, potential and spectroscopy. And the efficacy of multifunctional nanoparticles was evaluated in 4 T1 cell lines and M2 macrophages, including their cell uptake intracellular reactive oxygen species (ROS) production and the therapeutic effect. Furthermore, based on the orthotopic xenotransplantation model of triple negative breast cancer, the biological distribution, fluorescence imaging, biosafety evaluation and combined efficacy evaluation of the nanoplatform were performed.

FINDINGS

We have successfully prepared LyP-SA/AgNP@Dox and characterized. Administering the nanosystem to 4 T1 tumor cells or M2 macrophages in culture induced accumulation of reactive oxygen species, destruction of mitochondria and apoptosis, and inhibited replication and transcription. Animal experiments demonstrated the nanoparticle had favorable targeting and antitumor activity. Our nanosystem may be useful for simultaneously inhibiting tumor and tumor-associated macrophages in breast cancer and, potentially, other malignancies.