Project description:Skeletal muscle wasting is a devastating consequence of cancer that may be responsible for nearly 30% of cancer-related deaths. In addition to muscle atrophy, we have identified significant muscle fiber damage and replacement of muscle with fibrotic tissue in rectus abdominis muscle biopsies from cachectic pancreatic ductal adenocarcinoma (PDAC) patients that associates with poor survival. Transcriptional profiling of muscle harvested from these same patients supported these findings by identifying gene clusters related to wounding, inflammation and cellular response to TGF-B upregulated in cachectic PDAC patients compared with non-cancer controls. In this dataset, we include the expression data obtained from rectus abdominis muscle biopsies fron non-cancer controls patients undergoing abdominal surgery for benign reasons and from PDAC patients undergoing tumor-resection surgery. PDAC patients were further classified as non-cachectic or cachectic. Cachexia was defined as a body weight loss of >5% during the 6 months prior to surgery. The purpose of this study was to identify the broader transcriptional networks changed in cachectic PDAC patients versus non-cancer controls, that may be associated with the histological changes observed in muscle biopsies harvested from these same patients.
Project description:BackgroundCancer cachexia is a catabolic condition characterized by skeletal muscle wasting, consequent to tumor burden, which negatively impacts tolerance to cancer therapies and contributes to increased mortality. Partly because of the limited knowledge of the underlying mechanisms of cancer cachexia derived from human studies, however, the ability to therapeutically intervene remains elusive. The purpose of the current study was therefore to better define the phenotype of skeletal muscle obtained from patients with pancreatic ductal adenocarcinoma (PDAC), which has one of the highest rates of cachexia.MethodsMorphological analyses were performed on rectus abdominis muscle biopsies obtained from resectable PDAC patients undergoing tumor resection surgery (N = 20) and from weight-stable non-cancer control subjects undergoing benign abdominal surgery (N = 16). PDAC patients with a body weight loss of greater than 5% during the previous 6 months were considered cachectic (N = 15). Statistical tests were two sided.ResultsSkeletal muscle from cachectic PDAC patients had increased collagen content compared with non-cancer control subjects (1.43% vs 9.66%, P = .0004, Dunn test). Across all PDAC patients, collagen content positively correlated with body weight loss (P = .0016, r = 0.672), was increased in patients with lymph node metastasis (P = .007, Mann-Whitney U test), and was associated with survival on univariate (HR = 1.08, 95% confidence interval [CI] = 1.02 to 1.04, P = .008) and multivariable analyses (HR = 1.08, 95% CI = 1.00 to 1.17, P = .038). Cachectic PDAC patients also displayed increased lipid deposition (2.63% vs 5.72%, P = .042), infiltration of CD68+ macrophages (63.6 cells/mm2 vs 233.8 cells/mm2, P = .0238), calcium deposition (0.21% vs 2.51%, P = .030), and evidence of deficient cellular quality control mechanisms (Mann-Whitney U test). Transcriptional profiling of all patients supported these findings by identifying gene clusters related to wounding, inflammation, and cellular response to TGF-β upregulated in cachectic PDAC patients compared with non-cancer control subjects.ConclusionsTo our knowledge, this work is the first to demonstrate increased collagen content in cachectic PDAC patients that is associated with poor survival.
Project description:Radiotherapy (RT) reduces the risk of cancer recurrence and death, while accompanied by multiple side effects including muscle fibrosis and weakness, seriously affects the life quality of patients. However, the underlying mechanism is poorly defined. Here, we identify cancer cells secrete more spermidine synthase (SRM) enzyme through small extracellular vesicles (sEVs) to trigger skeletal muscle weakness upon RT. Mechanistically, RT-triggered arachidonic acid (ArA) accumulation elevates the ISGylation of SRM protein, facilitating SRM packaging into EVs from primary tumor. Circulating SRM results in spermidine accumulation in skeletal muscle and type I collagen fiber biosynthesis in an eIF5A-dependent manner. However, losartan treatment blocks the ISGylation of SRM and its subsequent secretion. Collectively, our findings determine that ArA functions in concert for circulating SRM secretion upon RT, which aggravates skeletal muscle fibrosis through rewiring polyamine metabolism, shedding light on the alleviation of RT-mediated muscle weakness when combined with losartan treatment.
Project description:Radiotherapy (RT) reduces the risk of cancer recurrence and death, while accompanied by multiple side effects including muscle fibrosis and weakness, seriously affects the life quality of patients. However, the underlying mechanism is poorly defined. Here, we identify cancer cells secrete more spermidine synthase (SRM) enzyme through small extracellular vesicles (sEVs) to trigger skeletal muscle weakness upon RT. Mechanistically, RT-triggered arachidonic acid (ArA) accumulation elevates the ISGylation of SRM protein, facilitating SRM packaging into EVs from primary tumor. Circulating SRM results in spermidine accumulation in skeletal muscle and type I collagen fiber biosynthesis in an eIF5A-dependent manner. However, losartan treatment blocks the ISGylation of SRM and its subsequent secretion. Collectively, our findings determine that ArA functions in concert for circulating SRM secretion upon RT, which aggravates skeletal muscle fibrosis through rewiring polyamine metabolism, shedding light on the alleviation of RT-mediated muscle weakness when combined with losartan treatment.
Project description:Skeletal muscle fibrosis, characterized by the replacement of functional muscle tissue with fibrotic scarring, leads to muscle function loss and potentially fatal respiratory failure, particularly in muscular dystrophy. The mechanisms driving muscle fibrosis is not yet fully understood. Our study utilized single-cell RNA-seq and single-nuclei ATAC-seq to analyze the transcriptome and chromatin accessibility of regenerating and dystrophic skeletal muscle, identifying a specific subset of fibro-adipogenic precursors (FAPs) enriched in dystrophic muscles, termed fibrotic FAPs. We further demonstrated that chronic inflammation upregulates Fosl1, an early response gene, which activates the expression of Kdm6b in fibrotic FAPs. Kdm6b, a histone demethylase, specifically removes the repressive histone H3K27me3 mark. Notably, targeting Kdm6b genetically and pharmacologically inhibits fibrotic di^erentiation in human and mouse FAPs in vitro and ameliorated muscle fibrosis in mouse models in vivo. Furthermore, constitutive activation of the Fosl1-Kdm6b pathway reduced H3K27me3 modification at critical fibrotic gene loci, leading to their transcriptional activation. Taken together, our findings reveal that chronic inflammation perpetuates the Fosl1-Kdm6b axis in FAPs, causing epigenomic reprogramming and altering the H3K27me3 landscape, which is essential for preventing fibrotic differentiation of FAPs and skeletal muscle fibrosis.
Project description:Skeletal muscle fibrosis, characterized by the replacement of functional muscle tissue with fibrotic scarring, leads to muscle function loss and potentially fatal respiratory failure, particularly in muscular dystrophy. The mechanisms driving muscle fibrosis is not yet fully understood. Our study utilized single-cell RNA-seq and single-nuclei ATAC-seq to analyze the transcriptome and chromatin accessibility of regenerating and dystrophic skeletal muscle, identifying a specific subset of fibro-adipogenic precursors (FAPs) enriched in dystrophic muscles, termed fibrotic FAPs. We further demonstrated that chronic inflammation upregulates Fosl1, an early response gene, which activates the expression of Kdm6b in fibrotic FAPs. Kdm6b, a histone demethylase, specifically removes the repressive histone H3K27me3 mark. Notably, targeting Kdm6b genetically and pharmacologically inhibits fibrotic di^erentiation in human and mouse FAPs in vitro and ameliorated muscle fibrosis in mouse models in vivo. Furthermore, constitutive activation of the Fosl1-Kdm6b pathway reduced H3K27me3 modification at critical fibrotic gene loci, leading to their transcriptional activation. Taken together, our findings reveal that chronic inflammation perpetuates the Fosl1-Kdm6b axis in FAPs, causing epigenomic reprogramming and altering the H3K27me3 landscape, which is essential for preventing fibrotic differentiation of FAPs and skeletal muscle fibrosis.
Project description:Skeletal muscle fibrosis, characterized by the replacement of functional muscle tissue with fibrotic scarring, leads to muscle function loss and potentially fatal respiratory failure, particularly in muscular dystrophy. The mechanisms driving muscle fibrosis is not yet fully understood. Our study utilized single-cell RNA-seq and single-nuclei ATAC-seq to analyze the transcriptome and chromatin accessibility of regenerating and dystrophic skeletal muscle, identifying a specific subset of fibro-adipogenic precursors (FAPs) enriched in dystrophic muscles, termed fibrotic FAPs. We further demonstrated that chronic inflammation upregulates Fosl1, an early response gene, which activates the expression of Kdm6b in fibrotic FAPs. Kdm6b, a histone demethylase, specifically removes the repressive histone H3K27me3 mark. Notably, targeting Kdm6b genetically and pharmacologically inhibits fibrotic di^erentiation in human and mouse FAPs in vitro and ameliorated muscle fibrosis in mouse models in vivo. Furthermore, constitutive activation of the Fosl1-Kdm6b pathway reduced H3K27me3 modification at critical fibrotic gene loci, leading to their transcriptional activation. Taken together, our findings reveal that chronic inflammation perpetuates the Fosl1-Kdm6b axis in FAPs, causing epigenomic reprogramming and altering the H3K27me3 landscape, which is essential for preventing fibrotic di^erentiation of FAPs and skeletal muscle fibrosis.
Project description:Radiotherapy (RT) reduces the risk of cancer recurrence and death, while accompanied by multiple side effects including muscle fibrosis and weakness, seriously affects the life quality of patients. However, the underlying mechanism is poorly defined. Here, we identify cancer cells secrete more spermidine synthase (SRM) enzyme through small extracellular vesicles (sEVs) to trigger skeletal muscle weakness upon RT. Mechanistically, RT-triggered arachidonic acid (ArA) accumulation elevates the ISGylation of SRM protein, facilitating SRM packaging into EVs from primary tumor. Circulating SRM results in spermidine accumulation in skeletal muscle and type I collagen fiber biosynthesis in an eIF5A-dependent manner. However, losartan treatment blocks the ISGylation of SRM and its subsequent secretion. Collectively, our findings determine that ArA functions in concert for circulating SRM secretion upon RT, which aggravates skeletal muscle fibrosis through rewiring polyamine metabolism, shedding light on the alleviation of RT-mediated muscle weakness when combined with losartan treatment.
Project description:D-galactose (D-gal) is a widely used chemical to induce cellular senescence. Cells undergoing senescence induced by D-gal exhibit mitochondrial structural damage and a decline in energy metabolism, which are highly related to cellular aging Studies have confirmed that D-gal can induce senescence, fibrosis, and redox imbalance in skeletal muscle fibroblasts. Our results confirm that D-galactose effectively induces cellular senescence and skeletal muscle fibrosis in both cellular and animal models. The increase in senescence markers and fibrosis-related proteins, along with the observed decline in muscle strength and mass, are consistent with previous studies that highlight the role of D-galactose in modeling aging-associated pathologies. The observed lethargy and reduction in muscle fiber cross-sectional area further validate the model's relevance to sarcopenia research.
Project description:Skeletal muscle fibrosis, characterized by the replacement of functional muscle tissue with fibrotic scarring, leads to muscle function loss and potentially fatal respiratory failure, particularly in muscular dystrophy. The mechanisms driving muscle fibrosis is not yet fully understood. Our study utilized single-cell RNA-seq and single-nuclei ATAC-seq to analyze the transcriptome and chromatin accessibility of regenerating and dystrophic skeletal muscle, identifying a specific subset of fibro-adipogenic precursors (FAPs) enriched in dystrophic muscles, termed fibrotic FAPs. We further demonstrated that chronic inflammation upregulates Fosl1, an early response gene, which activates the expression of Kdm6b in fibrotic FAPs. Kdm6b, a histone demethylase, specifically removes the repressive histone H3K27me3 mark. Notably, targeting Kdm6b genetically and pharmacologically inhibits fibrotic di^erentiation in human and mouse FAPs in vitro and ameliorated muscle fibrosis in mouse models in vivo. Furthermore, constitutive activation of the Fosl1-Kdm6b pathway reduced H3K27me3 modification at critical fibrotic gene loci, leading to their transcriptional activation. Taken together, our findings reveal that chronic inflammation perpetuates the Fosl1-Kdm6b axis in FAPs, causing epigenomic reprogramming and altering the H3K27me3 landscape, which is essential for preventing fibrotic di^erentiation of FAPs and skeletal muscle fibrosis.