DCX⁺ cells cripple systemic spleen immunity and promote tumor progression

The neuronal microtubule-associated protein doublecortin (DCX), traditionally known for its expression in neural precursor cells and its critical roles in neurogenesis and neuronal migration, has recently emerged as a potential player in cancer progression. However, its specific functions in tumor immunity remain largely unexplored. Here, we reveal a distinct central and peripheral distribution of DCX⁺ cells in human and murine cancers. In non-neurological solid tumors of human, DCX⁺ cells, as new tumor stromal components, may lack neuronal maturation capacity and exhibited a dopaminergic phenotype (NeuN^-/CD45^-/c-Kit^-/CD31⁺/TH⁺/DAT⁺), and localized within highly invasive stromal microenvironments. Their presence correlated with postoperative tumor recurrence and reduced circulating CD8⁺ T cells. In 4NQO-induced murine tumor models, DCX knockdown delayed tumor progression and restored systemic antitumor immunity, characterized by diminished immunosuppressive IRF4⁺ cDC2 cells and attenuated CD8⁺ T cell exhaustion in the spleen. Notably, DCX was absent in murine tumor tissues and spleen, suggesting that DCX-mediated systemic immune regulation exclusively involved brain DCX⁺ cells, which functionally connected to peripheral sympathetic innervation of ADRB2⁺ splenic immune cells. Depletion of DCX⁺ cells downregulated splenic neurotrophins, including PGF, FGF2, GDF15, and BMPs. Even under non-tumor conditions, DCX deficiency disrupted direct sympathetic nerve-CD8⁺ T cell interactions, unleashing CD8⁺ T cell activation and intrasplenic migration. Although mechanistic differences may exist between species, our findings identify DCX⁺ cells as a novel brake on T cell activation, bridging neural and immune regulation in cancer.