Background: Although chemodynamic therapy (CDT) has attracted enormous attention in anti-tumor studies for converting endogenous hydrogen peroxide (H₂O₂) into toxic hydroxyl radicals (•OH) by Fenton-type reaction, the treating effects of using CDT alone is still unsatisfying. Recently, glucose oxidase (GOx) was reported to be co-delivered with Fenton agent for synergistic starvation therapy (ST) and CDT. However, the overexpressed glutathione (GSH) and hypoxia in tumor microenvironment (TME) restrict the therapeutic efficacy of ST/CDT.
Methods and Results: In this work, a novel nanoplatform composed of GOx plus Fenton agent (Cu²⁺) encapsulated core and metformin (MET)-loaded manganese dioxide nanosheets (MNSs) shell was prepared and further functionalized by arginine-glycine-aspartate (RGD). With the RGD-mediated affinity with cancer cells, the nanocomposite (GOx-CuCaP@MNSs-MET@PEG-RGD, GCMMR) could accomplish targeting delivery and TME-activated release of cargos. The intracellular GSH was depleted by MnO₂/Cu²⁺ and abundant H₂O₂ was generated along with the GOx-induced glucose deprivation, which process was further enhanced by MET-mediated hypoxia relief via inhibiting mitochondria-associated respiration. Subsequently generated •OH from Cu⁺-mediated Fenton-like reaction exerts severe intracellular oxidative stress and cause apoptosis. Moreover, significant inhibition of tumor growth was detected in a subcutaneous xenograft model of osteosarcoma (OS) after GCMMR treatment.
Conclusion: The excellent therapeutic efficacy and biosafety of the nanoplatform were confirmed both in vitro and in vivo. Collectively, this study provides an appealing strategy with catalytic cascade enhancement on targeted ST/CDT for cancer treatment, especially for hypoxic solid tumors.
Keywords: chemodynamic therapy, starvation therapy, glucose oxidase, Fenton reaction, biomineralization, metformin