Tumor-induced alterations in single-nucleus transcriptome of atrophying muscles indicate enhanced protein degradation and reduced oxidative metabolism

Summary Tumor-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. We investigated muscle gene expression at single nucleus level in cachectic mice and revealed distinct myonuclear gene signatures and a shift towards type IIb myonuclei. Notably, atrophy-related genes, including Atrogin1 , MuRF1 and Eda2r were upregulated in these myonuclei, emphasizing their crucial role in muscle wasting. Activation of the Ectodysplasin A2 Receptor (EDA2R) pathway suppressed gene sets related to muscle contraction and oxidative metabolism, indicating its involvement in transcriptional reprogramming. Our study also highlighted the negative impact of tumors on oxidative metabolism in muscle tissue and their influence on the transcriptomes of mononuclear cells in skeletal muscle. These findings contribute to a deeper understanding of the molecular mechanisms underlying cancer cachexia.