Metal-organic Framework-based Nanoprobes For Reshaping The Tumor Microenvironment To Enhance Photodynamic Therapy Of Breast Cancer

BackgroudPhotodynamic therapy(PDT)exhibits emerging potentials against breast cancer,among which nanoscale metal-organic frameworks(MOFs)have attracted widespread attention in biomedical fields due to their unique structures in exerting efficient PDT for tumor treatment.Nevertheless,the complexity of the tumor microenvironment still poses great challenges to the photodynamic therapy of MOFs.It is still difficult to develop a precise co-delivery system integrating tumor microenvironment remodeling,efficient PDT,and synergistic therapy.In this study,based on PCN-224 porphyrin MOFs and Mn3O4 metallo-nanozyme,a synergistic therapeutic system,namely PCN224@Mn3O4@HA(PMH)nanoprobe was developed,which can drive oxygen production and glutathione depletion in the tumor microenvironment with combination of chemodynamic therapy(CDT)to enhance the effect of PDT.The composite nanoprobe can be used as a "reactive oxygen species activator" to effectively inhibit tumor growth and simultaneously exert its dual-modal imaging capabilities of fluorescence and magnetic resonance,which is expected to provide new ideas for individualized precision treatment of breast cancer.ObjectiveTo design and prepare PCN-224@Mn3O4@HA(PMH)nanoprobes,observe and verify its synergistic therapeutic effect on breast cancer at the solution level,cell level and in vivo level.MethodsPMH nanoprobe is synthesized via self-assembly and hydrothermal methods.The nanoprobe was characterized by transmission/scanning electron microscope,powder X-ray diffraction,ultraviolet-visible absorption spectrometer,dynamic light scattering and X-ray photoelectron spectroscopy.Dissolved oxygen instruments,glutathione kits,and methylene blue were used to test the catalytic performance and reactive oxygen species generation ability of the nanoprobe in solution.At the cellular level,the cytotoxicity and PDT effects of the nanoprobe were evaluated by MTT assay.The cellular uptake of the nanoprobe and its ability to induce oxygen production,glutathione depletion,reactive oxygen species generation,membrane lipid peroxidation,and the induction of necrosis and apoptosis in breast cancer cells were assessed by confocal microscopy and flow cytometry.At the in vivo level,a mouse model of breast cancer was constructed to evaluate the dual-modal imaging capability of the nanoprobe and its synergistic therapeutic effect in vivo.ResultsIn this study,the PMH nanoprobe was successfully constructed with a 200-nm particle size and a uniform polygonal shape under the electron microscope.It had good dispersion and was composed of five elements:carbon,nitrogen,oxygen,manganese,and zirconium.Solution experiment results:the nanoprobe exhibits catalase-like activity efficiently catalyzing hydrogen peroxide to produce oxygen.The nanoprobe displays glutathione peroxidase-like activity to consume glutathione.The Mn2+released from the nanoprobe after glutathione treatment induces a Fenton-like reaction to generate hydroxyl radicals.Under light conditions,the nanoprobe converts oxygen into singlet oxygen with high efficiency,which is better than the photodynamic effect of single PCN-224 under hypoxic conditions.Cellular experimental results:the MTT cytotoxicity assay demonstrated that the PMH nanoprobe exerts no biotoxicity on normal cells and has good biocompatibility,and the nanoprobe exhibits an excellent combined PDT/CDT therapeutic effect on breast cancer cells.Confocal microscopy and flow cytometry analysis showed that the nanoprobe is effectively taken up by tumor cells to alleviate cellular hypoxia,deplete intracellular glutathione,efficiently generate reactive oxygen species,induce lipid peroxidation,and lead to cell necrosis and apoptosis.In vivo experiment results:small animals fluorescence imaging showed that the nanoprobe accumulated in the tumor site of breast cancer mice,and reached the peak at 12 hours.The magnetic resonance T1-weighted signal exhibits a linear relationship with the concentration of the PMH nanoprobe,and the T1 signal is enhanced in the tumor site of mice after injection of the nanoprobe.The results of in vivo treatment showed that the nanoprobe exhibited excellent photodynamic and chemodynamic synergistic therapeutic effects on breast cancer mice with downregulating the expression of hypoxia-inducible factor-1α without obvious toxicity to vital organs.ConclusionThe designed and developed PMH nano-diagnosis and treatment system,through light-controlled reactive oxygen species formation and multi-modal imaging capabilities,can inhibit tumor proliferation and reshape the tumor microenvironment through PDT combined with CDT,which is expected to provide a new diagnosis and treatment strategy for breast cancer.