Objective Squalene epoxidase (SQLE) promotes metabolic dysfunction-associated steatohepatitis-associated hepatocellular carcinoma (MASH-HCC), but its role in modulating the tumour immune microenvironment in MASH-HCC remains unclear. Design We established hepatocyte-specific Sqle transgenic (tg) and knockout mice, which were subjected to a choline-deficient high-fat diet plus diethylnitrosamine to induce MASH-HCC. SQLE function was also determined in orthotopic and humanised mice. Immune landscape alterations of MASH-HCC mediated by SQLE were profiled by single-cell RNA sequencing and flow cytometry. Results Hepatocyte-specific Sqle tg mice exhibited a marked increase in MASH-HCC burden compared with wild-type littermates, together with decreased tumour-infiltrating functional IFN-γ+ and Granzyme B+ CD8+ T cells while enriching Arg-1+ myeloid-derived suppressor cells (MDSCs). Conversely, hepatocyte-specific Sqle knockout suppressed tumour growth with increased cytotoxic CD8+ T cells and reduced Arg-1+ MDSCs, inferring that SQLE promotes immunosuppression in MASH-HCC. Mechanistically, SQLE-driven cholesterol accumulation in tumour microenvironment underlies its effect on CD8+ T cells and MDSCs. SQLE and its metabolite, cholesterol, impaired CD8+ T cell activity by inducing mitochondrial dysfunction. Cholesterol depletion in vitro abolished the effect of SQLE-overexpressing MASH-HCC cell supernatant on CD8+ T cell suppression and MDSC activation, whereas cholesterol supplementation had contrasting functions on CD8+ T cells and MDSCs treated with SQLE-knockout supernatant. Targeting SQLE with genetic ablation or pharmacological inhibitor, terbinafine, rescued the efficacy of anti-PD-1 treatment in MASH-HCC models. Conclusion SQLE induces an impaired antitumour response in MASH-HCC via attenuating CD8+ T cell function and augmenting immunosuppressive MDSCs. SQLE is a promising target in boosting anti-PD-1 immunotherapy for MASH-HCC. All data relevant to the study are included in the article or uploaded as online supplemental information. All data supporting the findings of this study are available within the article and its online supplemental information.

中文翻译：

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靶向角鲨烯环氧化物酶可恢复代谢功能障碍相关脂肪性肝炎诱导的肝细胞癌的抗 PD-1 疗效


目的 角鲨烯环氧化物酶 （SQLE） 促进代谢功能障碍相关脂肪性肝炎相关肝细胞癌 （MASH-HCC），但其在调节 MASH-HCC 中肿瘤免疫微环境的作用仍不清楚。设计 我们建立了肝细胞特异性 Sqle 转基因 （tg） 和敲除小鼠，它们接受胆碱缺乏的高脂肪饮食加二乙基亚硝胺诱导 MASH-HCC。还在原位和人源化小鼠中确定了 SQLE 功能。通过单细胞 RNA 测序和流式细胞术分析 SQLE 介导的 MASH-HCC 免疫景观改变。结果 与野生型同窝小鼠相比，肝细胞特异性 Sqle tg 小鼠的 MASH-HCC 负荷显著增加，同时肿瘤浸润功能性 IFN-γ+ 和颗粒酶 B+ CD8+ T 细胞减少，同时富集 Arg-1+ 髓源性抑制细胞 （MDSC）。相反，肝细胞特异性 Sqle 敲除抑制了肿瘤生长，细胞毒性 CD8+ T 细胞增加，Arg-1+ MDSC 减少，推断 SQLE 促进 MASH-HCC 中的免疫抑制。从机制上讲，SQLE 驱动的胆固醇在肿瘤微环境中的积累是其对 CD8+ T 细胞和 MDSC 影响的基础。SQLE 及其代谢物胆固醇通过诱导线粒体功能障碍来损害 CD8+ T 细胞活性。体外胆固醇耗竭消除了 SQLE 过表达 MASH-HCC 细胞上清液对 CD8+ T 细胞抑制和 MDSC 活化的影响，而胆固醇补充剂对 CD8+ T 细胞和用 SQLE 敲除上清液处理的 MDSC 具有相反的功能。用基因消融或药物抑制剂特比萘芬靶向 SQLE，挽救了 MASH-HCC 模型中抗 PD-1 治疗的疗效。 结论 SQLE 通过减弱 CD8+ T 细胞功能和增强免疫抑制性 MDSC 诱导 MASH-HCC 抗肿瘤反应受损。SQLE 是促进 MASH-HCC 抗 PD-1 免疫治疗的有前途的靶点。与研究相关的所有数据都包含在文章中或作为在线补充信息上传。支持本研究结果的所有数据均可在文章及其在线补充信息中找到。