Cutaneous T-cell lymphoma (CTCL) incidence increases with age, and blood involvement portends a worse prognosis. To advance our understanding of CTCL development and identify potential therapeutic targets, we performed integrative analyses of paired single-cell RNA and TCR sequencing of peripheral blood CD4+ T-cells from CTCL patients to reveal disease unifying features. The malignant CD4+ T-cells of CTCL show highly diverse transcriptomic profiles across patients, with most displaying a mature Th2 differentiation and T-cell exhaustion phenotype. TCR-CDR3 peptide prediction analysis suggested limited diversity between CTCL samples, consistent with a role for a common antigenic stimulus. PHATE affinity-based transition analysis identified putative precancerous circulating populations characterized by an intermediate stage of gene expression and mutation level between the normal CD4+ T-cells and malignant CTCL cells. We further revealed the therapeutic potential of targeting CD82 and JAK that endow the malignant CTCL cells with survival and proliferation advantages.
CD8+ T cells play an important role in tumor immune surveillance and control. Better understanding of the regulation of their anti-tumor actions and improving their cytotoxic function and persistence will help advancing cancer immunotherapies. Here, we report the development of a step-wise CRISPR knockout (KO) screening strategy under the selection of TGF-β, a clinically relevant immunosuppressive pressure. The screen identifies Cul5 as a negative-feedback regulator of the core signaling pathways, differentiation, and persistence of CD8+ T cell. Cul5 KO in mouse CD8+ T cells significantly improves their tumor control ability in vitro and in vivo with significant proteomic alterations that generally enhance TCR and cytokine signaling, effector function, stemness, and survival of CD8+ T cell. Mechanistically, Cul5, whose protein content and active, neddylated form increase upon TCR-stimulation, interacts with SOCS-box-containing Pcmtd2 and negatively regulates TCR and IL2/STAT5 signaling by decreasing TCR and IL2 signaling molecules. Moreover, Cul5 KO in human CD8+ T cells phenocopies that in mouse CD8+ T cells. Furthermore, KO of CTLA4 that is markedly upregulated by Cul5 KO in mouse and human CD8+ cells further enhances anti-tumor effect of Cul5 KO, and a neddylation inhibitor enhances CD8 effector activities largely dependently of Cul5. These results together not only reveal a previously unknown negative-feedback regulatory mechanism for CD8+ T cells, but also have strong translational implications in cancer immunotherapy.
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