Project description:Cancer mediated activation of the ActRIIB-ALK4/5 heterodimer by myostatin is strongly associated with muscle wasting. Progressive skeletal muscle wasting, with or without loss of adipose tissue, is observed in up to 50 per cent of all cancer patients. This multifactorial syndrome is known as cachexia, and cannot be fully reversed by conventional nutritional support. Cachexia leads to progressive functional impairment. We investigated in vitro and in vivo the efficacy of ALK4/5 receptor blockers like SB431542 in preventing muscle wasting and in this context determined muscle-related miRNA expression profiles in non-tumor bearing control mice, in SB431542 treated C26 tumor-bearing mice and in cachectic C26 tumor-bearing mice.
Project description:Existing data suggest that NF-kappaB signaling is a key regulator of cancer-induced skeletal muscle wasting. However, identification of the components of this signaling pathway and of the NF-M-NM-:B transcription factors that regulate wasting is far from complete. In muscles of C26 tumor bearing mice, overexpression of d.n. IKKM-NM-2 blocked muscle wasting by 69%, the IM-NM-:BM-NM-1-super repressor blocked wasting by 41%. In contrast, overexpression of d.n. IKKM-NM-1 or d.n. NIK did not block C26-induced wasting. Surprisingly, overexpression of d.n. p65 or d.n. c-Rel did not significantly block muscle wasting. Genome-wide mRNA expression arrays showed upregulation of many genes previously implicated in muscle atrophy. To test if these upregulated genes were direct targets of NF-M-NM-:B transcription factors, we compared genome-wide p65 or p50 binding to DNA in control and cachectic muscle using ChIP-sequencing. Bioinformatic analysis of ChIP-seq data from control and C26 muscles showed increased p65 and p50 binding to a few regulatory and structural genes but only two of these genes were upregulated with atrophy. The p65 and p50 ChIP-seq data are consistent with our finding of no significant change in protein binding to an NF-M-NM-:B oligo in a gel shift assay. Taken together, these data support the idea that although inhibition of IM-NM-:BM-NM-1, and particularly IKKM-NM-2, blocks cancer-induced wasting, the alternative NF-M-NM-:B signaling pathway is not required. In addition, the downstream NF-M-NM-:B transcription factors do not regulate the transcriptional changes. These data are consistent with the growing body of literature showing that there are NF-M-NM-:B-independent substrates of IKKM-NM-2 and IM-NM-:BM-NM-1 that regulate physiological processes. To compare gene expression changes in atrophied muscles from C26 tumor bearing mice, gastrocnemius/plantaris muscles were harvested from 4 C26 tumor-bearing mice, and 3 control non tumor-bearing mice. Total RNA were isolated and pooled (2-3 muslces in the same group per RNA sample ) to make equal amount of total RNA per sample. Three pooled total RNA samples from healthy control muscles and 3 pooled total RNA from muscles of C26 tumor bearing mice were labelled and hybridized on 6 Mouse Affyemtrix Gene 1.0 ST arrays. Two-side t-tests and multiple test corrections were performed to identify differentially expressed genes due to C26 tumor bearing induced cachexia.
Project description:Advanced colorectal cancer (CRC), a leading cause of death worldwide, is often accompanied by the development of liver metastases (LM), as well as skeletal muscle (SkM) wasting, i.e. cachexia. Despite affecting the majority of CRC patients, cachexia remains understudied and uncured. Moreover, only a single model of LM associated with CRC has been developed for the study of cachexia. Here we examined differential gene expression of skeletal muscles deriving from subcutaneous and metastatic C26 tumor hosts. Tumor hosts displaying LM experienced exacerbated muscle wasting compared to tumor hosts without LM.
Project description:Cancer cachexia is a devastating metabolic syndrome characterized by systemic inflammation and massive muscle and adipose tissue wasting. Although cancer cachexia is responsible for approximately one third of cancer deaths, no effective therapies are available and the underlying mechanisms have not been fully elucidated.We have found that (+)-JQ1 administration protects tumor-bearing mice from body weight loss, muscle and adipose tissue wasting. Remarkably, in C26-tumor bearing mice (+)-JQ1 administration dramatically prolongs survival, without directly affecting tumor growth. By ChIP-seq analyses, we unveil that the BET proteins directly promote the muscle atrophy program during cachexia. Consistently, BET pharmacological blockade prevents the activation of catabolic genes associated with skeletal muscle atrophy and decreases IL6 systemic levels. Overall, these findings indicate that BET may represent a promising therapeutic target in the management of cancer cachexia.
Project description:Background Loss of skeletal muscle mass in advanced cancer is recognized as an independent predictor of mortality. Mechanisms involved in this wasting process and parameters for early diagnosis are still lacking. As skeletal muscle is considered as a secretory organ, the aim of this present experimental work was to characterize the changes in muscle proteome and secretome associated with cancer-induced cachexia to better understand cellular mechanisms involved in this wasting process and to identify secreted proteins which might reflect the ongoing muscle atrophy process. Methods We investigated first the changes in the muscle proteome associated with cancer-induced cachexia by using differential label-free proteomic analysis on muscle of the C26 mouse model. The differentially abundant proteins were submitted to sequential bioinformatic secretomic analysis in order to identify potentially secreted proteins. Selected reaction monitoring and Western blotting were used to verify the presence of candidate proteins at the circulating level. Their muscle source was demonstrated by assessing their gene expression in skeletal muscle and in cultured myotubes. Finally, we also investigated their regulation in muscle cells. Alterations in several molecular pathways potentially involved in muscle atrophy were highlighted using Gene ontology enrichment analyses. Results Our results revealed a dramatic increased production (2-to 25-fold) by the muscle of several acute phase reactants (APR: Haptoglobin, Serpina3n, Complement C3, Serum amyloid A1) which are also released in the circulation during C26 cancer cachexia. Their production was confirmed in other preclinical models of cancer cachexia as well as in cancer patients. The muscular origin of these APR was demonstrated by their increased expression in skeletal muscle and myotubes. Glucocorticoids and pro-inflammatory cytokines contribute directly to their increased expression in muscle cells in vitro, while the role of IL-6 in the muscular induction of these APR was demonstrated in vivo. Conclusions Cancer is associated with marked changes in muscle secretome during muscle wasting. Our study demonstrates a marked increased production of APR by skeletal muscle in pre-clinical models of cancer cachexia and in cancer patients. Further studies are required to unravel the potential role of these proteins in muscle atrophy and their interest as biomarkers of cancer cachexia.
Project description:Skeletal muscle wasting is a devastating consequence of cancer that affects up to 80% of cancer patients and associates with reduced survival. Herein we identified the transcriptional repressor protein, Forkhead box P1 (FoxP1), as a downstream target gene of FoxO1 whose skeletal muscle expression is elevated in multiple models of cancer cachexia and in patients with cancer who exhibit cachexia. Through generation of inducible skeletal muscle-specific FoxP1 over-expressing (FoxP1iSkmTg/Tg) mice, we demonstrate that FoxP1 upregulation is sufficient to induce features of cachexia, including body and skeletal muscle wasting characterized by reduced muscle fiber cross-sectional area of type IIX/B muscle fibers. Muscles from FoxP1iSkmTg/Tg mice also showed significant muscle damage and myopathy characterized by the accumulation of p62 and cellular material-filled vesicles, the presence of centrally nucleated myofibers, and were significantly weaker than controls. In the context of cancer cachexia, blocking FoxP1 upregulation prevented the cancer-induced repression of target genes critical to muscle structural integrity and repair, including Myocyte enhancer factor 2c (Mef2c), improved muscle ultrastructure and significantly attenuated muscle fiber atrophy. We further show that the muscle wasting phenotype induced by FoxP1 required the activity of histone deacetylase (HDAC) proteins, which are well-established to cooperate with FoxP1 to mediate gene repression, and which were necessary for FoxP1-dependent repression of Mef2c. In summary, we identify FoxP1 as a negative transcriptional regulator of skeletal muscle mass and function, whose up-regulation mediates cancer-induced muscle wasting. We used microarrays to investigate the genome-wide transcriptional networks regulated by the FoxO1 and FoxP1 transcription factors in skeletal muscle of tumor-bearing mice.
Project description:Cachexia is a systemic metabolic syndrome characterized by loss of fat and skeletal muscle mass in chronic wasting diseases such as cancer. The regulation of cellular protein synthesis in response to workload in skeletal muscle is generally blunted in cancer cachexia; however, the precise molecular regulation is largely unknown. In this study, to examine the molecular mechanism of skeletal muscle protein metabolism in cancer cachexia, we analyzed comprehensive gene expression in skeletal muscle using microarrays. CD2F1 mice (male, 7 weeks old) were subcutaneously transplanted (1*10^6 cells per mouse) with a mouse colon cancer-derived cell line (C26) as a model of cancer cachexia. Functional overload of the plantaris muscle by synergist ablation was performed at the 2nd week, and the plantaris muscle was sampled at the 4th week of cancer transplantation. The hypertrophy of skeletal muscle (increased skeletal muscle weight/protein synthesis efficiency and activation of mTOR signaling) associated with compensatory overload was significantly suppressed with the cancer cachexia. Gene expression profiling and pathway analysis by microarray showed that resistance to muscle protein synthesis associated with cancer cachexia was induced by downregulation of insulin-like growth factor-1. These observations show that cancer cachexia induces resistance to muscle protein synthesis, which could be a potential factor inhibiting the adaptation of skeletal muscle growth to physical exercise.
Project description:Background
Loss of skeletal muscle mass in cancer cachexia is recognized as an independent predictor of mortality. Mechanisms involved in this wasting process and parameters for early diagnosis are not yet clearly defined. As skeletal muscle is considered as a secretory organ, the aim of this present experimental work was to characterize the changes in the putative muscle secretome associated with cancer-induced cachexia to gain a better understanding of cellular mechanisms involved and to identify secreted proteins which might reflect this wasting process.
Methods
We investigated first the changes in the muscle proteome associated with cancer-induced cachexia by using differential label-free proteomic analysis on muscle of the C26 mouse model. The differentially abundant proteins were then submitted to sequential bioinformatic secretomic analysis in order to identify potentially secreted proteins. Multiple reaction monitoring and Western blotting were used to verify the presence of candidate proteins at the circulating level. Finally, we investigated the regulation of the production of these secreted proteins by muscle in vitro and in vivo.
Results
Our results revealed a dramatic increased muscular production (2-to 25-fold) of several acute phase reactants (APR: haptoglobin, serpina3n, complement C3, serum amyloid A1) which are released in the circulation during C26 cancer cachexia. This observation was confirmed in two other preclinical models of cancer cachexia as well as in cancer patients. The muscular origin of these APR was demonstrated by their increased expression in skeletal muscle and myotubes. Our results showed also that IL-6 plays a major role in the muscular induction of these APR in vivo, while glucocorticoids and pro-inflammatory cytokines stimulate directly their increased expression in muscle cells in vitro.
Conclusions
Muscle wasting caused by cancer is associated with marked changes in muscle secretome. Our study demonstrates a marked increased production of APR by skeletal muscle in pre-clinical models of cancer cachexia and in cancer patients. Further studies are required to unravel the potential role of these proteins in muscle atrophy and their interest as biomarkers of cancer cachexia.
Project description:Existing data suggest that NF-kappaB signaling is a key regulator of cancer-induced skeletal muscle wasting. However, identification of the components of this signaling pathway and of the NF-κB transcription factors that regulate wasting is far from complete. In muscles of C26 tumor bearing mice, overexpression of d.n. IKKβ blocked muscle wasting by 69%, the IκBα-super repressor blocked wasting by 41%. In contrast, overexpression of d.n. IKKα or d.n. NIK did not block C26-induced wasting. Surprisingly, overexpression of d.n. p65 or d.n. c-Rel did not significantly block muscle wasting. Genome-wide mRNA expression arrays showed upregulation of many genes previously implicated in muscle atrophy. To test if these upregulated genes were direct targets of NF-κB transcription factors, we compared genome-wide p65 or p50 binding to DNA in control and cachectic muscle using ChIP-sequencing. Bioinformatic analysis of ChIP-seq data from control and C26 muscles showed increased p65 and p50 binding to a few regulatory and structural genes but only two of these genes were upregulated with atrophy. The p65 and p50 ChIP-seq data are consistent with our finding of no significant change in protein binding to an NF-κB oligo in a gel shift assay. Taken together, these data support the idea that although inhibition of IκBα, and particularly IKKβ, blocks cancer-induced wasting, the alternative NF-κB signaling pathway is not required. In addition, the downstream NF-κB transcription factors do not regulate the transcriptional changes. These data are consistent with the growing body of literature showing that there are NF-κB-independent substrates of IKKβ and IκBα that regulate physiological processes.
Project description:Cancer-induced muscle wasting reduces quality of life, complicates or precludes cancer treatments, and predicts early mortality. Herein, we investigated the requirement of the muscle-specific E3 ubiquitin ligase, MuRF1, for muscle wasting induced by pancreatic cancer. Murine pancreatic cancer (KPC) cells, or saline, were injected into the pancreas of WT and MuRF1-/- mice, and tissues analyzed throughout tumor progression. KPC tumors induced progressive wasting of skeletal muscle and systemic metabolic reprogramming in WT mice, but not MuRF1-/- mice. KPC tumors from MuRF1-/- mice also grew slower, and showed an accumulation of metabolites normally depleted by rapidly growing tumors. Mechanistically, MuRF1 was necessary for the KPC-induced increases in cytoskeletal and muscle contractile protein ubiquitination, and the depression of proteins that support protein synthesis. Together, these data demonstrate that MuRF1 is required for KPC-induced skeletal muscle wasting, whose deletion reprograms the systemic and tumor metabolome and delays tumor growth.