癌症恶病质背景下肿瘤引起的骨骼肌消耗是一种对患者生存具有深远影响的疾病。肌肉质量的损失是一个重大的临床障碍，并且与化疗耐受性降低和虚弱加剧有关。了解驱动肌肉萎缩的分子机制对于新疗法的设计至关重要。刘易斯肺癌肿瘤被用来诱导小鼠恶病质和肌肉萎缩。使用 10X Genomics 应用程序按照制造商的指南构建了荷瘤小鼠及其非荷瘤对照的胫骨前肌 (TA) 肌肉的单核文库。 RNA 测序结果使用 Cell Ranger 软件和 Seurat R 软件包进行分析。使用 Oroboros O2k-FluoRespirometer 测量从 TA 肌肉分离的线粒体的耗氧量。用重组外胚增生素 A2 (EDA-A2) 蛋白处理小鼠原代肌管，以激活 EDA-A2 受体 (EDA2R) 信号传导并研究基因表达和耗氧量的变化。荷瘤小鼠在表现出中度恶病质时被处死。这些小鼠的平均 TA 肌肉重量减少了 11% (P = 0.0207)。总共研究了 12,335 个细胞核，其中包括来自对照组的 6422 个细胞核和来自萎缩肌肉的 5892 个细胞核。单核转录组分析发现了不同的肌核基因特征以及向 IIb 型肌核的转变。肌肉萎缩相关基因，包括 Atrogin1、MuRF1 和 Eda2r，在这些肌核中表达上调，强调了它们在肌肉萎缩中的关键作用。基因集富集分析表明，EDA2R 激活和肿瘤接种导致肌肉细胞中相似的表达模式，包括刺激核因子 -kappa B、Janus 激酶信号转导器和转录激活剂和转化生长因子 -β 途径以及抑制肌生成和氧化磷酸化。肌肉氧化代谢受到肿瘤和 EDA2R 激活的抑制。这项研究在单核分辨率下鉴定了肿瘤诱导的肌肉组织转录变化，并强调了肿瘤对氧化代谢的负面影响。这些发现有助于更深入地了解肌肉萎缩的分子机制。© 2024 作者。 《恶病质、肌肉减少症和肌肉杂志》由 Wiley periodicals LLC 出版。

Tumour-induced skeletal muscle wasting in the context of cancer cachexia is a condition with profound implications for patient survival. The loss of muscle mass is a significant clinical obstacle and is linked to reduced tolerance to chemotherapy and increased frailty. Understanding the molecular mechanisms driving muscle atrophy is crucial for the design of new therapeutics.Lewis lung carcinoma tumours were utilized to induce cachexia and muscle atrophy in mice. Single-nucleus libraries of the tibialis anterior (TA) muscle from tumour-bearing mice and their non-tumour-bearing controls were constructed using 10X Genomics applications following the manufacturer's guidelines. RNA sequencing results were analysed with Cell Ranger software and the Seurat R package. Oxygen consumption of mitochondria isolated from TA muscle was measured using an Oroboros O2k-FluoRespirometer. Mouse primary myotubes were treated with a recombinant ectodysplasin A2 (EDA-A2) protein to activate EDA-A2 receptor (EDA2R) signalling and study changes in gene expression and oxygen consumption.Tumour-bearing mice were sacrificed while exhibiting moderate cachexia. Average TA muscle weight was reduced by 11% (P = 0.0207) in these mice. A total of 12 335 nuclei, comprising 6422 nuclei from the control group and 5892 nuclei from atrophying muscles, were studied. The analysis of single-nucleus transcriptomes identified distinct myonuclear gene signatures and a shift towards type IIb myonuclei. Muscle atrophy-related genes, including Atrogin1, MuRF1 and Eda2r, were upregulated in these myonuclei, emphasizing their crucial roles in muscle wasting. Gene set enrichment analysis demonstrated that EDA2R activation and tumour inoculation led to similar expression patterns in muscle cells, including the stimulation of nuclear factor-kappa B, Janus kinase-signal transducer and activator of transcription and transforming growth factor-beta pathways and the suppression of myogenesis and oxidative phosphorylation. Muscle oxidative metabolism was suppressed by both tumours and EDA2R activation.This study identified tumour-induced transcriptional changes in muscle tissue at single-nucleus resolution and highlighted the negative impact of tumours on oxidative metabolism. These findings contribute to a deeper understanding of the molecular mechanisms underlying muscle wasting.© 2024 The Author(s). Journal of Cachexia, Sarcopenia and Muscle published by Wiley Periodicals LLC.