ABSTRACT
In clinical practice, the treatment of colon cancer is faced with the dilemma of metastasis and recurrence, which is related to immunosuppression and hypoxia. Immune checkpoint blockade (ICB) is a negative regulatory pathway of immunity. Immune checkpoint blockade (ICB) is an important immunotherapy method. However, inadequate immunogenicity reduces the overall response rate of ICB. In this study, a tumor microenvironment-responsive nanomedicine (Cu-FACD@MnO2@FA) was prepared to increase host immune response and increase intracellular oxygen levels. Cu-FACD@MnO2@FA preferentially enriched at the tumor site, combined with the immune checkpoint inhibitor alpha PD-L1, induced sufficient immunogenicity to treat colon cancer. Immunofluorescence detection of tumor cells and tissues showed that the expression of hypoxa-inducing factor 1α was significantly down-regulated after treatment and the expression of immunoactivity-related proteins was significantly changed. In vivo treatment in a bilateral tumor mouse model showed complete ablation of the primary tumor and efficient inhibition of the distal tumor. In this study, for the first time, the oxygenation effects of MnO2-coated Cu-doped carbon dots and chemodynamic therapy and a strategy of combining with immuno-blocking therapy were used for treating colon cancer.
Subject(s)
Carbon , Colonic Neoplasms , Copper , Folic Acid , Manganese Compounds , Oxides , Manganese Compounds/chemistry , Manganese Compounds/pharmacology , Animals , Oxides/chemistry , Oxides/pharmacology , Copper/chemistry , Colonic Neoplasms/drug therapy , Colonic Neoplasms/pathology , Mice , Carbon/chemistry , Humans , Folic Acid/chemistry , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/therapeutic use , Oxygen/chemistry , Quantum Dots/chemistry , Cell Line, Tumor , Mice, Inbred BALB C , Tumor Microenvironment/drug effectsABSTRACT
Cancer immune escape, metastasis, recurrence, and multidrug resistance are all associated with hypoxia in the tumor microenvironment (TME). We synthesized a CuPPaCC conjugate for reactive oxygen species (ROS)-mediated cancer therapy. CuPPaCC continuously produced cytotoxic ROS and oxygen through a photo-chemocycloreaction, alleviated hypoxia, and inhibited the expression of a hypoxia-inducing factor (HIF-1α). CuPPaCC was synthesized from pyromania phyllophyllic acid a (PPa), cystine (CC), and copper ions, and its structure was characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). The ability of CuPPaCC to produce ROS and oxygen after photodynamic therapy (PDT) in vitro and in vivo was investigated. The ability of CuPPaCC to consume glutathione was investigated. CuPPaCC toxicity (light and dark) in CT26 cells was analyzed by MTT and live/dead cell staining. The anticancer effect of CuPPaCC in vivo was investigated in CT26 Balb/c mice. When stimulated by the TME, CuPPaCC released Cu2+ and PPaCC, and the singlet oxygen yield increased from 34 to 56.5%. The dual ROS-generating mechanism via a Fenton-like reaction/photoreaction and dual glutathione depletion via Cu2+/CC multiplied the antitumor efficacy of CuPPaCC. The photo-chemocycloreaction continued to produce oxygen and maintained high ROS levels even after PDT, significantly alleviating hypoxia in the TME and downregulating the expression of HIF-1α. CuPPaCC thus showed excellent antitumor activity in vitro and in vivo. These results showed that the strategy could be effective in improving the antitumor efficacy of CuPPaCC and could be used as a synergistic regimen for cancer therapy.
