TET2-mediated tumor cGAS triggers endothelial STING activation to regulate vasculature remodeling and anti-tumor immunity in liver cancer.

Induction of tumor vascular normalization is a crucial measure to enhance immunotherapy efficacy. cGAS-STING pathway is vital for anti-tumor immunity, but its role in tumor vasculature is unclear. Herein, using preclinical liver cancer models in Cgas/Sting-deficient male mice, we report that the interdependence between tumor cGAS and host STING mediates vascular normalization and anti-tumor immune response. Mechanistically, TET2 mediated IL-2/STAT5A signaling epigenetically upregulates tumor cGAS expression and produces cGAMP. Subsequently, cGAMP is transported via LRRC8C channels to activate STING in endothelial cells, enhancing recruitment and transendothelial migration of lymphocytes. In vivo studies in male mice also reveal that administration of vitamin C, a promising anti-cancer agent, stimulates TET2 activity, induces tumor vascular normalization and enhances the efficacy of anti-PD-L1 therapy alone or in combination with IL-2. Our findings elucidate a crosstalk between tumor and vascular endothelial cells in the tumor immune microenvironment, providing strategies to enhance the efficacy of combinational immunotherapy for liver cancer.

Inhibition of ACLY overcomes cancer immunotherapy resistance via polyunsaturated fatty acids peroxidation and cGAS-STING activation.

Adenosine 5'-triphosphate citrate lyase (ACLY) is a cytosolic enzyme that converts citrate into acetyl-coenzyme A for fatty acid and cholesterol biosynthesis. ACLY is up-regulated or activated in many cancers, and targeting ACLY by inhibitors holds promise as potential cancer therapy. However, the role of ACLY in cancer immunity regulation remains poorly understood. Here, we show that ACLY inhibition up-regulates PD-L1 immune checkpoint expression in cancer cells and induces T cell dysfunction to drive immunosuppression and compromise its antitumor effect in immunocompetent mice. Mechanistically, ACLY inhibition causes polyunsaturated fatty acid (PUFA) peroxidation and mitochondrial damage, which triggers mitochondrial DNA leakage to activate the cGAS-STING innate immune pathway. Pharmacological and genetic inhibition of ACLY overcomes cancer resistance to anti-PD-L1 therapy in a cGAS-dependent manner. Furthermore, dietary PUFA supplementation mirrors the enhanced efficacy of PD-L1 blockade by ACLY inhibition. These findings reveal an immunomodulatory role of ACLY and provide combinatorial strategies to overcome immunotherapy resistance in tumors.

ATP-citrate lyase regulates stemness and metastasis in hepatocellular carcinoma via the Wnt/ß-catenin signaling pathway.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most highly malignant tumors. Liver tumor-initiating cells (LTICs) have been considered to contribute to HCC progression and metastasis. ATP-citrate lyase (ACLY), as a key enzyme for de novo lipogenesis, has been reported to be upregulated in various tumors. However, its expression and role in HCC and LTICs remain unknown. METHODS: The expressions of ACLY in HCC tissues were detected by quantitative real-time PCR (qRT-PCR), Western blotting and immunohistochemistry. Kaplan-Meier curves and Chi-square test were used to determine the clinical significance of ACLY expression in HCC patients. A series of assays were performed to determine the function of ACLY on stemness, migration and invasion of HCC cells. Luciferase reporter assay, Western blotting and immunoprecipitation were used to study the regulation of the Wnt/ß-catenin signaling by ACLY. Rescue experiments were performed to investigate whether ß-catenin was the mediator of ACLY-regulated stemness and migration in HCC cells. RESULTS: ACLY was highly expressed in HCC tissues and LTICs. Overexpression of ACLY was significantly correlated with poor prognosis, progression and metastasis of HCC patients. Knockdown of ACLY remarkably suppressed stemness properties, migration and invasion in HCC cells. Mechanistically, ACLY could regulate the canonical Wnt pathway by affecting the stability of ß-catenin, and Lys49 acetylation of ß-catenin might mediate ACLY-regulated ß-catenin level in HCC cells. CONCLUSIONS: ACLY is a potent regulator of Wnt/ß-catenin signaling in modulating LTICs stemness and metastasis in HCC. ACLY may serve as a new target for the diagnosis and treatment of HCC.

NAD+ Metabolism Maintains Inducible PD-L1 Expression to Drive Tumor Immune Evasion.

NAD+ metabolism is implicated in aging and cancer. However, its role in immune checkpoint regulation and immune evasion remains unclear. Here, we find nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ biogenesis, drives interferon γ (IFNγ)-induced PD-L1 expression in multiple types of tumors and governs tumor immune evasion in a CD8+ T cell-dependent manner. Mechanistically, NAD+ metabolism maintains activity and expression of methylcytosine dioxygenase Tet1 via α-ketoglutarate (α-KG). IFNγ-activated Stat1 facilitates Tet1 binding to Irf1 to regulate Irf1 demethylation, leading to downstream PD-L1 expression on tumors. Importantly, high NAMPT-expressing tumors are more sensitive to anti-PD-L1 treatment and NAD+ augmentation enhances the efficacy of anti-PD-L1 antibody in immunotherapy-resistant tumors. Collectively, these data delineate an NAD+ metabolism-dependent epigenetic mechanism contributing to tumor immune evasion, and NAD+ replenishment combined with PD-(L)1 antibody provides a promising therapeutic strategy for immunotherapy-resistant tumors.

[Spectrum-activity relationship of trichosanthis fructus and trichosanthis fructus strip pieces for rat myocardial ischemia-reperfusion injury].

To investigate the spectrum-activity relationship of Trichosanthis Fructus and Trichosanthis Fructus strip pieces for rat myocardial ischemia-reperfusion injury. HPLC fingerprints of Trichosanthis Fructus and Trichosanthis Fructus strip pieces were established, and the values of creatinekinase-MB (CK-MB), myoglobin (MYO) and cardiac troponin-T (cTNT) in 3 dose groups (2.25, 13.5, 27.0 g·kg⁻¹, equivalent to the crude herb g·kg⁻¹) of Trichosanthis Fructus and Trichosanthis Fructus strip pieces with myocardial ischemia-reperfusion injury in rats were measured, and the grey relational analysis was used to study the spectrum-activity relationship of Trichosanthis Fructus and Trichosanthis Fructus strip pieces for rat myocardial ischemia-reperfusion injury. With the dosage increase from 2.25 g·kg⁻¹ to 27.0 g·kg⁻¹, the correlation degree of spectrum-activity relationship of Trichosanthis Fructus and Trichosanthis Fructus strip pieces was also enhanced, but the change trend was different between these two groups. According to the frequency of the top 10 peaks in the correlation degree, peak 17, 14, 16, 19, 32, 12, 26, 30, 4, 6 and 2 were the basic effective substances group of Trichosanthis Fructus, peak 6,14,12,32,30,4 and 6 were the basic effective substances group of Trichosanthis Fructus strip pieces. Peak 6, 14, 12, 32, 30, 4 and 26 in fingerprints of Trichosanthis Fructus and Trichosanthis Fructus strip pieces were the main common pharmacodynamic substance base, among them, peak 6 was 5-hydroxymethyl furfural, peak 14 was vanillic acid and the peak 28 was rutin, but the correlation degree with the efficacy was different. The effect of Trichosanthis Fructus and Trichosanthis Fructus strip pieces on rat myocardial ischemia-reperfusion injury was due to the synergistic effect of the effective substance groups related to the dosage. The essential pharmacodynamic substance groups of Trichosanthis Fructus and Trichosanthis Fructus strip pieces were different, but they shared a common active ingredient group.