This study developed a novel redox-responsive selenium-containing nanomedicine, NP2, capable of simultaneously inhibiting the GSH and Trx antioxidant systems, enhancing cisplatin efficacy, and inducing immunogenic cell death, thereby significantly improving the antitumor effects of immune checkpoint therapy.
Literature Overview
The article titled 'A Redox-Responsive Selenium-Containing Nanomedicine Enables Dual Antioxidant System Inhibition to Overcome Platinum Resistance and Enhance Immunotherapy in Bladder Cancer,' published in the journal ACS Nano, reviews and summarizes the development of a novel selenium-containing polymeric nanomedicine, NP2. By responding to high intracellular glutathione (GSH) levels in tumor cells, NP2 releases a platinum(IV) prodrug while simultaneously disrupting the two major antioxidant systems—GSH and thioredoxin (Trx)—thereby overcoming platinum resistance, enhancing chemotherapy efficacy, and activating antitumor immune responses through induction of immunogenic cell death (ICD). The study further confirms that combining NP2 with a PD-1 antibody significantly suppresses the growth of both primary and distant tumors and prevents recurrence, offering a novel combination strategy for bladder cancer treatment. This work systematically reveals the synergistic role of dual antioxidant system inhibition in chemosensitization and immune activation, demonstrating significant translational medical value.Background Knowledge
Bladder cancer is the second most common urological malignancy worldwide. For muscle-invasive bladder cancer (MIBC), the standard first-line treatment is cisplatin-based chemotherapy. However, despite initial response rates of 50%–70%, most patients rapidly develop platinum resistance, leading to treatment failure. A key mechanism of resistance is the overactivation of intracellular antioxidant systems in tumor cells, particularly the glutathione (GSH) system, which can inactivate platinum by direct binding. Additionally, the thioredoxin (Trx) system also contributes to maintaining cellular redox balance and enhancing cell survival. Previous studies have largely focused on inhibiting a single antioxidant system, but with limited clinical success, suggesting that dual system inhibition may be a more effective strategy. Meanwhile, immune checkpoint inhibitors (e.g., anti–PD-1/PD-L1 antibodies) have shown promise in bladder cancer, but their efficacy is limited by the 'immune-cold' tumor microenvironment and low PD-L1 expression. Thus, converting 'immune-cold' tumors into 'immune-hot' tumors while overcoming platinum resistance remains a major challenge. This study addresses this clinical dilemma by designing a nanomedicine with dual functions—chemosensitization and immune activation—using materials chemistry to simultaneously target the GSH and Trx systems, offering an innovative solution to the dual challenges of drug resistance and immune suppression.
Research Methods and Experiments
Researchers designed and synthesized an amphiphilic polymer, P2, containing diselenide bonds, which self-assembled with the platinum(IV) prodrug Pt(IV)-CLB to form nanoparticles, NP2. The size, morphology, and chemical structure of NP2 were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). In vitro experiments employed multiple bladder cancer cell lines (T24, BIU-87, UMUC3, MB49) to evaluate NP2's cytotoxicity, cellular uptake efficiency, reactive oxygen species (ROS) generation, GSH depletion, DNA damage (via γ-H2AX detection), and release of immunogenic cell death (ICD) markers (CRT, HMGB1, ATP). Western blotting was used to assess Trx reductase and PD-L1 protein expression. RNA sequencing analyzed differentially expressed genes and pathway enrichment following drug treatment. In a murine MB49 subcutaneous xenograft model, in vivo imaging assessed NP2's biodistribution and tumor targeting. The antitumor effects of NP2 alone or in combination with an anti–PD-1 antibody were evaluated, with immunohistochemistry and flow cytometry used to analyze immune cell infiltration in the tumor microenvironment (dendritic cell maturation, CD8+ T cells, macrophage polarization, MDSCs) and PD-L1 expression levels.Key Conclusions and Perspectives
Research Significance and Prospects
This study innovatively combines materials science with tumor immune metabolism regulation. The developed NP2 nanomedicine not only addresses the long-standing clinical challenge of platinum resistance but also achieves synergistic enhancement of chemotherapy and immunotherapy through ICD induction. Its dual antioxidant system inhibition mechanism provides a new strategy for overcoming tumor redox adaptability, with broad potential applicability.
Future studies could further explore the platform's application in other platinum-resistant tumors, optimize drug ratios and delivery efficiency, and advance its clinical translation. Additionally, whether this strategy is applicable in combination with other immunotherapies (e.g., CAR-T, cancer vaccines) warrants further investigation. This work provides an important paradigm for developing multifunctional nanomedicines, advancing the development of precision and immune-oriented cancer therapies.
Conclusion
This study successfully developed a redox-responsive, selenium-containing nanomedicine, NP2, which effectively overcomes platinum resistance in bladder cancer and enhances chemotherapy efficacy by simultaneously inhibiting the GSH and Trx antioxidant systems. Upon releasing cisplatin within tumor cells, NP2 disrupts cellular antioxidant defenses, leading to substantial ROS accumulation, thereby inducing immunogenic cell death, activating dendritic cells, promoting CD8+ T cell infiltration, and reprogramming tumor-associated macrophages toward M1 polarization, significantly improving the immunosuppressive microenvironment. NP2 alone significantly inhibits tumor growth and upregulates PD-L1 expression, and when combined with anti–PD-1 antibody, demonstrates potent synergistic antitumor effects, effectively controlling both primary and distant lesions and eliciting immune memory to prevent tumor recurrence. This study not only provides a highly promising new therapeutic strategy for bladder cancer but also demonstrates the feasibility of achieving dual benefits—chemosensitization and immune activation—through redox balance modulation, offering important conceptual and practical guidance for the development of next-generation multifunctional nanomedicines.
