Assembly of a biomimetic copper-based nanocomplex for alleviating hypoxia to enhance cuproptosis against osteosarcoma and lung metastasis.

Osteosarcoma tissues demonstrated elevated expression of proteins (FDX1 and DLAT) integral to cuproptosis in our preliminary study, indicating the potential effectiveness of anti-tumor strategies predicated on this process. Nevertheless, the overexpression of copper export proteins and the challenge of copper ion penetration may contribute to insufficient local copper ion concentration for inducing cuproptosis. Herein, we engineered a biomimetic copper-elesclomol-polyphenol network for the efficient delivery of copper ions and the copper ionophore elesclomol. Simultaneously, we integrated catalase (CAT) to alleviate tumor hypoxia, thereby inducing a greater reliance of tumor cells on aerobic respiration and enhancing cuproptosis sensitivity. In vitro analyses revealed that the nanocomplex exhibited potent cytotoxicity and displayed hallmark characteristics of cuproptosis. In vivo trials further validated targeted tumor accumulation, resulting in the suppression of tumor growth and lung metastasis. An augmentation in the proportion of activated immune cells in both tumor and draining lymph nodes was observed. The improvement of immunosuppressive microenvironment facilitated a synergistic antitumor effect with cuproptosis. The therapeutic efficacy was further evidenced in two osteosarcoma models, highlighting the potential as a safe and effective strategy against osteosarcoma and lung metastasis. STATEMENT OF SIGNIFICANCE: Osteosarcoma tissues exhibit a marked increase in the expression of proteins FDX1 and DLAT, which are crucial for cuproptosis. Moreover, cells that depend on mitochondrial respiration are more susceptible to cuproptosis. Here we developed a biomimetic copper-based nanocomplex to trigger cuproptosis against osteosarcoma and lung metastases. The nanocomplex demonstrated excellent biocompatibility and tumor targeting. Catalase incorporating facilitated oxygen generation within tumor microenvironment and alleviated hypoxia, thereby inducing a greater reliance of tumor cells on aerobic respiration and enhancing cuproptosis sensitivity. Simultaneously, the released Cu-elesclomol complexes induced proteotoxic stress responses and efficiently elicited cuproptosis, leading to increased release of proinflammatory factors and triggering anti-tumor immune activation. Our strategy holds promise for osteosarcoma treatment by inducing cuproptosis and achieving potent tumor suppression.