Project description:Retinoic acid-inducible gene I (RIG-I) is a pattern recognition receptor involved in innate immunity, but its role in adaptive immunity, specifically in the context of CD8+ T-cell antitumour immunity, remains unclear. Here, we demonstrate that RIG-I is upregulated in tumour-infiltrating CD8+ T cells, where it functions as an intracellular checkpoint to negatively regulate CD8+ T-cell function and limit antitumour immunity. Mechanistically, the upregulation of RIG-I in CD8+ T cells is induced by activated T cells, and directly inhibits the AKT/glycolysis signalling pathway. In addition, knocking out RIG-I enhances the efficacy of adoptively transferred T cells against solid tumours, and inhibiting RIG-I enhances the response to PD-1 blockade. Overall, our study identifies RIG-I as an intracellular checkpoint and a potential target for alleviating inhibitory constraints on T cells in cancer immunotherapy, either alone or in combination with an immune checkpoint inhibitor.
Project description:RIG-I is a pattern recognition receptor involved in innate immunity, but its role in adaptive immunity remains unclear. Here, we demonstrate that RIG-I is upregulated in tumor infiltrating CD8+ T cells, where it functions as an intracellular checkpoint to negatively regulate CD8+ T cell function and limit antitumor immunity. Mechanically, up-regulation of RIG-I in CD8+ T cells is induced by retinoic acid (RA), a metabolite of vitamin A in TME, and direct inhibits the AKT/glycolysis signaling pathway. In addition, deletion of RIG-I enhances the efficacy of adoptively transferred T cells against solid tumors and inhibition of RIG-I enhances the response to PD-1 blockade. Our findings identify RIG-I as an intracellular checkpoint and a potential target for alleviating inhibitory constraints on T cells in cancer immunotherapy, either alone or in combination with immune checkpoint blockade.
Project description:Neuropilin-1 (Nrp-1) is a marker for murine CD4+FoxP3+ regulatory T (Treg) cells, a subset of human CD4+ Treg cells, and a population of CD8+ T cells infiltrating certain solid tumours. However, whether Nrp-1 regulates tumour-specific CD8 T-cell responses is still unclear. Here we show that Nrp-1 defines a subset of CD8+ T cells displaying PD-1hi status and infiltrating human lung cancer. Interaction of Nrp-1 with its ligand semaphorin-3A inhibits migration and tumour-specific lytic function of cytotoxic T lymphocytes. In vivo, Nrp-1+PD-1hi CD8+ tumour-infiltrating lymphocytes (TIL) in B16F10 melanoma are enriched for tumour-reactive T cells exhibiting an exhausted state, expressing Tim-3, LAG-3 and CTLA-4 inhibitory receptors. Anti-Nrp-1 neutralising antibodies enhance the migration and cytotoxicity of Nrp-1+PD-1hi CD8+ TIL ex vivo, while in vivo immunotherapeutic blockade of Nrp-1 synergises with anti-PD-1 to enhance CD8+ T-cell proliferation, cytotoxicity and tumour control. Thus, Nrp-1 could be a target for developing combined immunotherapies.
Project description:Checkpoint blockade therapies have improved cancer treatment, but such immunotherapy regimens fail in a large subset of patients. Conventional type 1 dendritic cells (DC1s) control the response to checkpoint blockade in preclinical models and are associated with better overall survival in patients with cancer, reflecting the specialized ability of these cells to prime the responses of CD8+ T cells1-3. Paradoxically, however, DC1s can be found in tumours that resist checkpoint blockade, suggesting that the functions of these cells may be altered in some lesions. Here, using single-cell RNA sequencing in human and mouse non-small-cell lung cancers, we identify a cluster of dendritic cells (DCs) that we name 'mature DCs enriched in immunoregulatory molecules' (mregDCs), owing to their coexpression of immunoregulatory genes (Cd274, Pdcd1lg2 and Cd200) and maturation genes (Cd40, Ccr7 and Il12b). We find that the mregDC program is expressed by canonical DC1s and DC2s upon uptake of tumour antigens. We further find that upregulation of the programmed death ligand 1 protein-a key checkpoint molecule-in mregDCs is induced by the receptor tyrosine kinase AXL, while upregulation of interleukin (IL)-12 depends strictly on interferon-γ and is controlled negatively by IL-4 signalling. Blocking IL-4 enhances IL-12 production by tumour-antigen-bearing mregDC1s, expands the pool of tumour-infiltrating effector T cells and reduces tumour burden. We have therefore uncovered a regulatory module associated with tumour-antigen uptake that reduces DC1 functionality in human and mouse cancers.
Project description:Immunotherapies aimed at alleviating the inhibitory constraints on T cells have revolutionized cancer management. To date, these have focused on the blockade of cell-surface checkpoints such as PD-1. Herein we identify protein tyrosine phosphatase 1B (PTP1B) as an intracellular checkpoint that is upregulated in T cells in tumors. We show that increased PTP1B limits T-cell expansion and cytotoxicity to contribute to tumor growth. T cell-specific PTP1B deletion increased STAT5 signaling, and this enhanced the antigen-induced expansion and cytotoxicity of CD8+ T cells to suppress tumor growth. The pharmacologic inhibition of PTP1B recapitulated the T cell-mediated repression of tumor growth and enhanced the response to PD-1 blockade. Furthermore, the deletion or inhibition of PTP1B enhanced the efficacy of adoptively transferred chimeric antigen receptor (CAR) T cells against solid tumors. Our findings identify PTP1B as an intracellular checkpoint whose inhibition can alleviate the inhibitory constraints on T cells and CAR T cells to combat cancer.SignificanceTumors subvert antitumor immunity by engaging checkpoints that promote T-cell exhaustion. Here we identify PTP1B as an intracellular checkpoint and therapeutic target. We show that PTP1B is upregulated in intratumoral T cells and that its deletion or inhibition enhances T-cell antitumor activity and increases CAR T-cell effectiveness against solid tumors. This article is highlighted in the In This Issue feature, p. 587.
Project description:Accumulating evidence suggests that metabolic rewiring in malignant cells supports tumour progression not only by providing cancer cells with increased proliferative potential and an improved ability to adapt to adverse microenvironmental conditions but also by favouring the evasion of natural and therapy-driven antitumour immune responses. Here, we review cancer cell-intrinsic and cancer cell-extrinsic mechanisms through which alterations of metabolism in malignant cells interfere with innate and adaptive immune functions in support of accelerated disease progression. Further, we discuss the potential of targeting such alterations to enhance anticancer immunity for therapeutic purposes.
Project description:Ubiquitylation is pivotal in regulating cellular responses, with its aberration implicated in tumor immune evasion. However, the impact of ubiquitin-conjugating enzymes (E2s) on this evasion remains unclear. Here, we employ a systematic approach to demonstrate that in pancreatic ductal carcinoma (PDAC), the inflammatory microenvironment induces overexpression of the E2 enzyme UBE2D3, contributing to tumor progression through non-oncogene codependent disorders. Through gene expression analyses and functional investigations, we elucidate a mechanism wherein cancer cells evade T cell immune responses by UBE2D3 binding to the ubiquitin ligase KLHL13 to co-ubiquitinate TAP2. This K63-linkage ubiquitination at the lysine 245 site of TAP2 impedes antigenic peptide transport by the TAP1/TAP2 complex, hindering p-MHC assembly and presentation in cancer cells. We demonstrate that genetic inhibition of UBE2D3 enhances tumor-specific CD8+ T cell proliferation and extends effector-memory-like phenotypes. Building on this, we develop a small-molecule inhibitor, QX-6, targeting the active site of UBE2D3 to disrupt its function. Pharmacologic inhibition of UBE2D3 blocks the ubiquitylation of antigen presentation-related substrates, leading to increased p-MHC presentation by cancer cells and reduced T cell exhaustion. Using immunocompetent and humanized models, we elucidate the therapeutic efficacy of targeting UBE2D3. Furthermore, we evaluate the synergistic anti-tumor effects of QX-6 in combination with KRAS-targeted TCR-T cell immunotherapy. In summary, our study reveals a post-translational modification mechanism wherein the intracellular checkpoint UBE2D3 regulates the TAP2 switch to control cancer cell evasion of CTLs, presenting a potential immunotherapeutic strategy to improve PDAC treatment outcomes.