Maimonides Biomedical Research Institute of Córdoba (IMIBIC), Córdoba, Spain.
Cancer Network Biomedical Research Centre (CIBERONC), Madrid, Spain.
J Pathol. 2023 Jul;260(3):261-275. doi: 10.1002/path.6080. Epub 2023 Apr 5.
S-nitrosoglutathione reductase (GSNOR) is a denitrosylase enzyme that has been suggested to play a tumor suppressor role, although the mechanisms responsible are still largely unclear. In this study, we show that GSNOR deficiency in tumors is associated with poor prognostic histopathological features and poor survival in patients with colorectal cancer (CRC). GSNOR-low tumors were characterized by an immunosuppressive microenvironment with exclusion of cytotoxic CD8 T cells. Notably, GSNOR-low tumors exhibited an immune evasive proteomic signature along with an altered energy metabolism characterized by impaired oxidative phosphorylation (OXPHOS) and energetic dependence on glycolytic activity. CRISPR-Cas9-mediated generation of GSNOR gene knockout (KO) CRC cells confirmed in vitro and in vivo that GSNOR-deficiency conferred higher tumorigenic and tumor-initiating capacities. Moreover, GSNOR-KO cells possessed enhanced immune evasive properties and resistance to immunotherapy, as revealed following xenografting them into humanized mouse models. Importantly, GSNOR-KO cells were characterized by a metabolic shift from OXPHOS to glycolysis to produce energy, as indicated by increased lactate secretion, higher sensitivity to 2-deoxyglucose (2DG), and a fragmented mitochondrial network. Real-time metabolic analysis revealed that GSNOR-KO cells operated close to their maximal glycolytic rate, as a compensation for lower OXPHOS levels, explaining their higher sensitivity to 2DG. Remarkably, this higher susceptibility to glycolysis inhibition with 2DG was validated in patient-derived xenografts and organoids from clinical GSNOR-low tumors. In conclusion, our data support the idea that metabolic reprogramming induced by GSNOR deficiency is an important mechanism for tumor progression and immune evasion in CRC and that the metabolic vulnerabilities associated with the deficiency of this denitrosylase can be exploited therapeutically. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
谷胱甘肽 S-亚硝基转移酶（GSNOR）是一种脱亚硝基酶，据推测其具有肿瘤抑制作用，但其作用机制仍在很大程度上不明确。在本研究中，我们发现肿瘤中 GSNOR 的缺失与结直肠癌（CRC）患者预后不良的组织病理学特征和生存率降低有关。GSNOR 低表达的肿瘤具有免疫抑制性微环境，细胞毒性 CD8 T 细胞被排斥在外。值得注意的是，GSNOR 低表达的肿瘤表现出免疫逃避的蛋白质组学特征，同时伴有能量代谢改变，表现为氧化磷酸化（OXPHOS）受损和对糖酵解活性的能量依赖性增强。CRISPR-Cas9 介导的 GSNOR 基因敲除（KO）CRC 细胞的生成在体外和体内证实，GSNOR 缺失赋予了更高的肿瘤发生和肿瘤起始能力。此外，GSNOR-KO 细胞具有增强的免疫逃避特性和对免疫治疗的抗性，这是通过将它们移植到人源化小鼠模型中得到证实的。重要的是，GSNOR-KO 细胞表现出从 OXPHOS 向糖酵解的代谢转变，以产生能量，这表现为乳酸分泌增加、对 2-脱氧葡萄糖（2DG）的敏感性增加和线粒体网络碎片化。实时代谢分析显示，GSNOR-KO 细胞的糖酵解率接近最大值，以弥补 OXPHOS 水平的降低，这解释了它们对 2DG 的更高敏感性。值得注意的是，在患者来源的异种移植和临床 GSNOR 低表达肿瘤的类器官中，用 2DG 抑制糖酵解的更高敏感性得到了验证。总之，我们的数据支持这样的观点，即 GSNOR 缺失引起的代谢重编程是 CRC 肿瘤进展和免疫逃避的重要机制，并且与该脱亚硝基酶缺乏相关的代谢脆弱性可以在治疗上得到利用。
