Quercetin-derived microbial metabolite DOPAC potentiates CD8⁺ T cell anti-tumor immunity via NRF2-mediated mitophagy.

Abstract

Quercetin, a dietary flavonol, shows promise in cancer prevention, though its effects on the immune compartment within the tumor microenvironment are not fully understood. Here, we identify 3,4-dihydroxyphenylacetic acid (DOPAC), a microbial metabolite of quercetin, as a critical mediator of its anti-tumor effects in a CD8⁺ T cell-dependent manner. Mechanistically, DOPAC directly binds to Kelch-like epichlorohydrin-associated protein 1 (KEAP1), disrupting its interaction with nuclear factor erythroid 2-related factor 2 (NRF2) and preventing KEAP1-mediated degradation of NRF2 in CD8⁺ T cells. Elevated NRF2 transcriptionally enhances the expression of B cell lymphoma 2-interacting protein 3, promoting mitophagy and mitochondrial functionality, which improves CD8⁺ T cell fitness within the tumor microenvironment. Furthermore, DOPAC synergizes with immune checkpoint blockade to suppress tumor growth. Our findings underscore the role of microbial metabolites of dietary nutrients in modulating anti-tumor immune responses, positioning DOPAC as a promising candidate for cancer immunotherapy.