Study On Anti-breast Cancer Of Co-delivery Nanoparticles Targeting Tumor-associated Macrophages And Tumor Cells Combined With Immunochemotherapy

Breast cancer accounts for about 30%of all female cancers with high morbidity and mortality,and is the most common cancer.So far,the treatment of cancer patients is mainly based on chemotherapy drugs.However,chemotherapy alone generally can not distinguish between malignant and normal proliferative cells,and may cause adverse toxicity to normal tissues such as heart,liver,and kidney.Moreover,the use of chemotherapy drugs will induce drug resistance in tumor cells,which will seriously affect the treatment process of cancer chemotherapy drugs.Breast cancer produces a large number of proliferating abnormal cells,and has a high-density immunosuppressive microenvironment composed of a large number of immunosuppressive cells.Tumor immunotherapy rebuild the tumor microenvironment to improve the ability of anti-tumor immunity,recognize and kill tumor cells.Therefore,combination therapy has become a new cancer treatment method.The combination of chemotherapy and immunotherapy for the treatment of solid tumors such as breast cancer induces tumor cell apoptosis,and correct or regulate the tumor immunosuppressive microenvironment,which is expected to improve the treatment effect.However,free drugs often cause systemic discomfort.Therefore,to find a better treatment for breast cancer has become the new direction.Chemotherapy and immune drugs are accurately delivered to the corresponding target cells to protect normal cells while killing tumor cells.In this study,doxorubicin（DOX）and immunomodulator（R848）were used to treat breast cancer.The tumor-targeted transmembrane peptide（R6RGD）and the M2 macrophage-targeting peptide（M2pep）were respectively coupled with carboxymethyl-β-cyclodextrin（CMβCD）and carboxymethyl chitosan（CMCS）by amide condensation reaction to prepare R6RGD-CMβCD and M2pep-CMCS.R6RGD-CMβCD loaded DOX nanoparticles(RCNP_DOX)were prepared by saturated solution method,and M2pep-CMCS loaded R848 nanoparticles(MCNP_R848)were prepared by solvent evaporation method.These two nanoparticles were injected into mice via tail vein by physical mixing.In this design,RCNP_DOX directly targeted tumor cells and directly released DOX to kill tumor cells.MCNP_R848 targeted M2 macrophages and released R848 to polarize M2 macrophages into M1 macrophages,reducing the level of tumor immunosuppression.The polarization of TAMs can increase the secretion of tumor necrosis factor-α（TNF-α）,rebuild the tumor immunosuppressive microenvironment,enhance the effect of immunotherapy,and indirectly kill tumor cells.In addition,the release characteristics of nanoparticles were also investigated.Our results showed that we had successfully developed a drug delivery system that combines chemotherapy and immunotherapy by targeting 4T1 cells and M2 macrophages.RCNP_DOX and MCNP_R848 had obvious targeting effect on breast cancer cells and M2 macrophages,respectively.MCNP_R848 could effectively transform tumor-promoting M2 macrophages into tumor-inhibiting M1 macrophages.At the same time,it was found that RCNP_DOX and MCNP_R848 had a synergistic cytotoxic effect,and there was an interaction between tumor cells and macrophages.In addition,the system combined with RCNP_DOX and MCNP_R848 could induce more apoptosis of breast cancer cells than single agent.Importantly,combination of RCNP_DOX and MCNP_R848 had good anti-cancer effects in vivo.At the same time,the prepared nanoparticles had good biocompatibility and no obvious toxicity.In general,this strategy provides a new way with obvious advantages for improving the efficiency of cancer treatment.