Project description:We report an in situ vaccination, adaptable to nearly any type of cancer, that combines radiotherapy targeting one tumor and intratumoral injection of this site with tumor-specific antibody and interleukin-2 (IL-2; 3xTx). In a phase I clinical trial, administration of 3xTx (with an immunocytokine fusion of tumor-specific antibody and IL-2, hu14.18-IL2) to subjects with metastatic melanoma increases peripheral CD8+ T cell effector polyfunctionality. This suggests the potential for 3xTx to promote antitumor immunity against metastatic tumors. In poorly immunogenic syngeneic murine melanoma or head and neck carcinoma models, 3xTx stimulates CD8+ T cell-mediated antitumor responses at targeted and non-targeted tumors. During 3xTx treatment, natural killer (NK) cells promote CTLA4+ regulatory T cell (Treg) apoptosis in non-targeted tumors. This is dependent on NK cell expression of CD86, which is upregulated downstream of KLRK1. NK cell depletion increases Treg infiltration, diminishing CD8+ T cell-dependent antitumor response. These findings demonstrate that NK cells sustain and propagate CD8+ T cell immunity following 3xTx
Project description:Natural killer (NK) cells are central to innate antitumor immunity, yet their function is systemically compromised in colorectal cancer (CRC). We show that CRC patients exhibit early and pronounced alterations in peripheral blood NK cells, marked by a reduced frequency of total CD56⁺ cells, a shift toward CD56lowCD16⁺ subset, and impaired cytotoxic and cytokine responses. Notably, plasma from CRC patients, particularly those with advanced disease, induces similar dysfunction in healthy donor (HD) NK cells, suppressing mTORC1 signaling and effector activity. Transcriptomic profiling of HD NK cells exposed to CRC plasma revealed downregulation of TNF-α signaling components, concordant with reduced systemic and intracellular TNF-α levels in patients. Additionally, CRC plasma suppressed the JAK-STAT pathway and upregulated SOCS family genes, further dampening NK cell responsiveness. Inhibition of TNF-α in HD NK cells recapitulated the CRC plasma–induced defects, while exogenous TNF-α partially restored NK cell function, including STAT5 and S6 phosphorylation. These findings uncover TNF-α signaling deficiency as a systemic mechanism of NK cell suppression in CRC, linking impaired metabolism to immune evasion. Targeting this axis may offer a novel strategy to reinvigorate NK cell–mediated antitumor immunity in CRC.
Project description:Natural killer (NK) cells play pivotal roles in antitumor immunity, yet their connection to tumor metabolism remains unclear. Our systematic analysis of multiomics data and survival data from colorectal cancer (CRC) patients uncovered a novel association between mitochondrial acetyl-CoA acetyltransferase 1 (ACAT1) and NK cell infiltration that influences disease progression. ACAT1, a metabolic enzyme involved in reversible conversion of acetoacetyl-CoA to two molecules of acetyl-CoA, exhibits nuclear protein acetylation activity through its translocation. Under immune stimulation, mitochondrial ACAT1 can be phosphorylated at serine 60 (S60) and enters the nucleus; however, this process is hindered in nutrient-poor tumor microenvironments. Nuclear ACAT1 directly acetylates lysine 146 of p50 (NFKB1), attenuating its DNA binding and transcriptional repression activity and thereby increasing the expression of immune-related factors, which in turn promotes NK cell recruitment and activation to suppress colorectal cancer growth. Furthermore, significant associations were found among low nuclear ACAT1 levels, decreased S60 phosphorylation, and reduced NK cell infiltration, as well as poor prognosis in CRC. Our findings reveal an unexpected function of ACAT1 as a nuclear acetyltransferase and elucidate its role in NK cell-dependent antitumor immunity through p50 acetylation.
Project description:Uncoupling protein 1 (UCP1) is a mitochondrial inner membrane protein whose main function is to mediate non-shivering thermogenesis. Dysregulated expression of UCP1 contributes to the pathogenesis of multiple diseases, including cancer. Natural killer (NK) cells, key effectors of antitumor immunity, are substantially impaired in the tumor microenvironment (TME). Here, we showed that UCP1 expression is markedly downregulated in tumor-infiltrating NK (TINK) cells from both colorectal cancer (CRC) patients and tumor-bearing mice and is correlated with impaired effector function. In the TME, TGF-β1 and hypoxia repress the transcription of UCP1 through the downregulation of C/EBPβ. NK cell-specific ablation of UCP1 accelerated tumor growth and reduced the infiltration of TINKs. RNA sequencing revealed an increase in NLRP3 inflammasome-mediated pyroptosis in Ucp1–/– NK cells. UCP1 deficiency synergized with TME stress to increase the uptake of fatty acids and oxidative phosphorylation via the upregulation of CD36/FABP4. This induces mitochondrial damage and excessive release of mitochondrial DNA (mtDNA), triggering the activation of the NLRP3 inflammasome and NK cell pyroptosis. Enforced UCP1 expression in NK cells prevents TME-induced pyroptosis, maintains the antitumor activity in both murine models and patient-derived organoids. Genetically modified expression of UCP1 in NK cells is a potential therapy for patients with tumors.