Tumor-Specific Peroxynitrite Overproduction Disrupts Metabolic Homeostasis for Sensitizing Melanoma Immunotherapy.

Tumor cells elicit metabolic reprogramming to establish an immunosuppressive tumor microenvironment (TME) for escaping from immunosurveillance. Therefore, interrupting the metabolic adaptation of tumor cells may be a promising strategy for TME immunomodulation, favoring immunotherapy. In this work, a tumor-specific peroxynitrite nanogenerator APAP-P-NO is constructed that can selectively disrupt metabolic homeostasis in melanoma cells. Stimulated by melanoma-characteristic acid, glutathione, and tyrosinase, APAP-P-NO can efficiently generate peroxynitrite through the in situ coupling of the produced superoxide anion and released nitric oxide. Metabolomics profiling reveals that the accumulated peroxynitrite induces a great decrease in metabolites in the tricarboxylic acid cycle. Meanwhile, the glycolysis-produced lactate drops sharply both intracellularly and extracellularly under peroxynitrite stress. Mechanistically, peroxynitrite impairs the activity of glyceraldehyde-3-phosphate dehydrogenase in glucose metabolism through S-nitrosylation. The metabolic alterations effectively reverse the immunosuppressive TME to evoke potent antitumor immune responses, including polarization of M2-like macrophages to M1phenotype, reduction of myeloid-derived suppressor cells and regulatory T cells, and restoration of CD8 T cell infiltration. Combining APAP-P-NO with anti-PD-L1 achieves a significant inhibition against both primary and metastatic melanomas without systemic toxicities. Collectively, a tumor-specific peroxynitrite overproduction approach is developed and the possible mechanism of peroxynitrite-mediated TME immunomodulation is explored, providing a new strategy for facilitating immunotherapy sensitivity.