A multifunctional PD-L1 modulator for metabolic reprogramming to induce pyroptosis and enhance glutamine inhibition-mediated antitumor immunotherapy

Metabolic interference strategies offer promising interventions in tumor therapy. However, inhibiting glutamine metabolism can upregulate Programmed Cell Death Ligand 1 (PD-L1), resulting in immune evasion and limiting the efficacy of glutamine inhibitors. Here, a nano-modulator with multi-enzyme interactions, DPG@COD/CuMOF@Dz, is introduced. It combines metabolic management and immunotherapy by incorporating copper metal-organic framework nanoparticles containing cholesterol oxidase (COD) and DNAzyme (Dz), as well as particles modified with DSPE-PEG-glutamine (DPG). Once internalized, the nano-modulator releases COD, Cu²⁺, and Dz in response to the high intracellular GSH environment. Cu²⁺ activates Dz, which inhibits glutaminase production and glutamine metabolism in cancer cells. Meanwhile, COD depletes cholesterol from cancer cell membranes, decreasing PD-L1 stability and abundance. COD produces hydrogen peroxide, which combines with Cu²⁺ via Fenton-like processes to produce ·OH, raising intracellular reactive oxygen species (ROS) levels. Additionally, GLS Dz effectively suppresses glutamine metabolism, thereby diminishing intracellular glutathione (GSH) synthesis and disrupting the redox homeostasis in cancer cells. These cascading events collectively initiate pyroptosis and immunogenic cell death (ICD), which not only attenuates PD-L1-mediated immune evasion but also provokes a robust antitumor immune response. Notably, combination therapy employing the nano-modulator and an αPD-1 antibody achieved a remarkable tumor inhibition rate of 93.7%. This work presents a promising strategy to overcome the challenges associated with glutamine blockade, offering an innovative therapeutic paradigm for the treatment of breast cancer. STATEMENT OF SIGNIFICANCE: This study develops a novel nano-modulator (DPG@COD/CuMOF@Dz) that co-targets glutamine metabolism and PD-L1 stability via cholesterol depletion for enhanced cancer immunotherapy. By integrating enzymatic activity and metal-organic frameworks for synergistic redox disruption and immune activation, it overcomes limitations of conventional inhibitors and offers a "three-in-one" strategy to reverse immunosuppression. This work provides new insights into metabolic-immune crosstalk and presents a promising combinatory platform to boost immune checkpoint therapy.