Mohr Hermine, Ballke Simone, Bechmann Nicole, Gulde Sebastian, Malekzadeh-Najafabadi Jaber, Peitzsch Mirko, Ntziachristos Vasilis, Steiger Katja, Wiedemann Tobias, Pellegata Natalia S
Institute for Diabetes and Cancer, Helmholtz Centre Munich, Ingolstaedter Landstr.1, 85764 Neuherberg, Germany.
Joint Heidelberg-IDC Translational Diabetes Program, Heidelberg University Hospital, 69120 Heidelberg, Germany.
Cancers (Basel). 2021 Jan 2;13(1):126. doi: 10.3390/cancers13010126.
Pseudohypoxic tumors activate pro-oncogenic pathways typically associated with severe hypoxia even when sufficient oxygen is present, leading to highly aggressive tumors. Prime examples are pseudohypoxic pheochromocytomas and paragangliomas (p-PPGLs), neuroendendocrine tumors currently lacking effective therapy. Previous attempts to generate mouse models for p-PPGLs all failed. Here, we describe that the rat MENX line, carrying a (p27) frameshift-mutation, spontaneously develops pseudohypoxic pheochromocytoma (p-PCC).
We compared rat p-PCCs with their cognate human tumors at different levels: histology, immunohistochemistry, catecholamine profiling, electron microscopy, transcriptome and metabolome. The vessel architecture and angiogenic potential of pheochromocytomas (PCCs) was analyzed by light-sheet fluorescence microscopy ex vivo and multi-spectral optoacoustic tomography (MSOT) in vivo.
The analysis of tissues at various stages, from hyperplasia to advanced grades, allowed us to correlate tumor characteristics with progression. Pathological changes affecting the mitochrondrial ultrastructure where present already in hyperplasias. Rat PCCs secreted high levels of norepinephrine and dopamine. Transcriptomic and metabolomic analysis revealed changes in oxidative phosphorylation that aggravated over time, leading to an accumulation of the oncometabolite 2-hydroxyglutarate, and to hypermethylation, evident by the loss of the epigenetic mark 5-hmC. While rat PCC xenografts showed high oxygenation, induced by massive neoangiogenesis, rat primary PCC transcriptomes possessed a pseudohypoxic signature of high , , and low expression, thereby clustering with human p-PPGL.
Endogenous rat PCCs recapitulate key phenotypic features of human p-PPGLs. Thus, MENX rats emerge as the best available animal model of these aggressive tumors. Our study provides evidence of a link between cell cycle dysregulation and pseudohypoxia.
假性低氧肿瘤即使在有充足氧气的情况下也会激活通常与严重缺氧相关的促癌途径，从而导致高侵袭性肿瘤。典型例子是假性低氧嗜铬细胞瘤和副神经节瘤（p-PPGLs），这是目前缺乏有效治疗方法的神经内分泌肿瘤。此前生成p-PPGLs小鼠模型的尝试均告失败。在此，我们描述了携带（p27）移码突变的大鼠MENX品系会自发发生假性低氧嗜铬细胞瘤（p-PCC）。
我们在不同层面比较了大鼠p-PCC与其对应的人类肿瘤：组织学、免疫组织化学、儿茶酚胺谱分析、电子显微镜检查、转录组和代谢组。通过离体光片荧光显微镜和体内多光谱光声断层扫描（MSOT）分析嗜铬细胞瘤（PCCs）的血管结构和血管生成潜力。
对从增生到高级别阶段的不同组织阶段进行分析，使我们能够将肿瘤特征与进展相关联。影响线粒体超微结构的病理变化在增生阶段就已存在。大鼠PCC分泌高水平的去甲肾上腺素和多巴胺。转录组和代谢组分析揭示了氧化磷酸化的变化，这种变化随时间加剧，导致肿瘤代谢物2-羟基戊二酸积累，并导致高甲基化，表观遗传标记5-hmC的缺失即为明证。虽然大鼠PCC异种移植瘤因大量新生血管生成而表现出高氧合状态，但大鼠原发性PCC转录组具有高、、低表达的假性低氧特征，从而与人类p-PPGL聚类。
内源性大鼠PCC概括了人类p-PPGL的关键表型特征。因此，MENX大鼠成为这些侵袭性肿瘤的最佳可用动物模型。我们的研究提供了细胞周期失调与假性低氧之间存在联系的证据。
