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STAT3 activation in skeletal muscle links muscle wasting and the acute phase response in cancer cachexia.

Bonetto A, Aydogdu T, Kunzevitzky N, Guttridge DC, Khuri S, Koniaris LG, Zimmers TA - PLoS ONE (2011)

Bottom Line: In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response.These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer.These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such that amino acids liberated by increased proteolysis in cachexia are synthesized into acute phase proteins and exported into the blood.

View Article: PubMed Central - PubMed

Affiliation: Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, United States of America.

ABSTRACT

Background: Cachexia, or weight loss despite adequate nutrition, significantly impairs quality of life and response to therapy in cancer patients. In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response. Acute phase proteins, including fibrinogen and serum amyloid A (SAA) are synthesized by hepatocytes in response to IL-6 as part of the innate immune response. To gain insight into the relationships among these observations, we studied mice with moderate and severe Colon-26 (C26)-carcinoma cachexia.

Methodology/principal findings: Moderate and severe C26 cachexia was associated with high serum IL-6 and IL-6 family cytokines and highly similar patterns of skeletal muscle gene expression. The top canonical pathways up-regulated in both were the complement/coagulation cascade, proteasome, MAPK signaling, and the IL-6 and STAT3 pathways. Cachexia was associated with increased muscle pY705-STAT3 and increased STAT3 localization in myonuclei. STAT3 target genes, including SOCS3 mRNA and acute phase response proteins, were highly induced in cachectic muscle. IL-6 treatment and STAT3 activation both also induced fibrinogen in cultured C2C12 myotubes. Quantitation of muscle versus liver fibrinogen and SAA protein levels indicates that muscle contributes a large fraction of serum acute phase proteins in cancer.

Conclusions/significance: These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer. Through IL-6/STAT3 activation, skeletal muscle is induced to synthesize acute phase proteins, thus establishing a molecular link between the observations of high IL-6, increased acute phase response proteins and muscle wasting in cancer. These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such that amino acids liberated by increased proteolysis in cachexia are synthesized into acute phase proteins and exported into the blood.

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Robust expression of acute phase response proteins in skeletal muscle versus liver in C26 cachexia.A. Western blotting and quantitation of fibrinogen levels in control and C26 quadriceps and liver. Data (mean ± SEM) are expressed as relative densitometry value. **P<0.01, ***P<0.001. B, Western blotting analysis of fibrinogen standard proteins and quadriceps and liver extracts for control, CHO-IL6 injected nude mice and C26 injected CD2F1 mice. Quantitation was performed on the band indicated by the arrow. Data (means ± SEM) are expressed as ng fibrinogen / µg protein. *P<0.05, **P<0.01, ***P<0.001. C, Western blotting analysis demonstrates significantly increased fibrinogen and SAA1 protein levels in quadriceps and gastrocnemius in moderate and severe C26 cachexia. *P<0.05, **P<0.01, ***P<0.001.
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pone-0022538-g007: Robust expression of acute phase response proteins in skeletal muscle versus liver in C26 cachexia.A. Western blotting and quantitation of fibrinogen levels in control and C26 quadriceps and liver. Data (mean ± SEM) are expressed as relative densitometry value. **P<0.01, ***P<0.001. B, Western blotting analysis of fibrinogen standard proteins and quadriceps and liver extracts for control, CHO-IL6 injected nude mice and C26 injected CD2F1 mice. Quantitation was performed on the band indicated by the arrow. Data (means ± SEM) are expressed as ng fibrinogen / µg protein. *P<0.05, **P<0.01, ***P<0.001. C, Western blotting analysis demonstrates significantly increased fibrinogen and SAA1 protein levels in quadriceps and gastrocnemius in moderate and severe C26 cachexia. *P<0.05, **P<0.01, ***P<0.001.

Mentions: Given the robust induction of acute phase gene RNA in cachexia (Figure 5), we sought to confirm expression at the protein level. By Western blotting analysis, levels of the secreted protein fibrinogen in quadriceps extracts were increased 2–12 fold in mice with C26 cachexia versus controls, depending upon which band is quantified (Figure 7A). In liver, fibrinogen protein levels were increased 2–5 fold (Figure 7A). Measuring fibrinogen signal against a standard curve of purified murine fibrinogen, normal quadriceps contained approximately 0.9 ng fibrinogen per µg of protein, while quadriceps in C26 cachexia contained 1.9 ng/µg (Figure 7B), a ∼2-fold increase. Normal liver contained 1.8 ng/µg fibrinogen, while liver in C26 cachexia contained 5.2 ng/µg fibrinogen, a ∼3-fold increase. Fibrinogen expression was also increased in quadriceps as well as liver in response to administration of IL-6 (Figure 7B), suggesting this may be a general response to conditions of high IL-6 and not limited to cancer.


STAT3 activation in skeletal muscle links muscle wasting and the acute phase response in cancer cachexia.

Bonetto A, Aydogdu T, Kunzevitzky N, Guttridge DC, Khuri S, Koniaris LG, Zimmers TA - PLoS ONE (2011)

Robust expression of acute phase response proteins in skeletal muscle versus liver in C26 cachexia.A. Western blotting and quantitation of fibrinogen levels in control and C26 quadriceps and liver. Data (mean ± SEM) are expressed as relative densitometry value. **P<0.01, ***P<0.001. B, Western blotting analysis of fibrinogen standard proteins and quadriceps and liver extracts for control, CHO-IL6 injected nude mice and C26 injected CD2F1 mice. Quantitation was performed on the band indicated by the arrow. Data (means ± SEM) are expressed as ng fibrinogen / µg protein. *P<0.05, **P<0.01, ***P<0.001. C, Western blotting analysis demonstrates significantly increased fibrinogen and SAA1 protein levels in quadriceps and gastrocnemius in moderate and severe C26 cachexia. *P<0.05, **P<0.01, ***P<0.001.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3140523&req=5

pone-0022538-g007: Robust expression of acute phase response proteins in skeletal muscle versus liver in C26 cachexia.A. Western blotting and quantitation of fibrinogen levels in control and C26 quadriceps and liver. Data (mean ± SEM) are expressed as relative densitometry value. **P<0.01, ***P<0.001. B, Western blotting analysis of fibrinogen standard proteins and quadriceps and liver extracts for control, CHO-IL6 injected nude mice and C26 injected CD2F1 mice. Quantitation was performed on the band indicated by the arrow. Data (means ± SEM) are expressed as ng fibrinogen / µg protein. *P<0.05, **P<0.01, ***P<0.001. C, Western blotting analysis demonstrates significantly increased fibrinogen and SAA1 protein levels in quadriceps and gastrocnemius in moderate and severe C26 cachexia. *P<0.05, **P<0.01, ***P<0.001.
Mentions: Given the robust induction of acute phase gene RNA in cachexia (Figure 5), we sought to confirm expression at the protein level. By Western blotting analysis, levels of the secreted protein fibrinogen in quadriceps extracts were increased 2–12 fold in mice with C26 cachexia versus controls, depending upon which band is quantified (Figure 7A). In liver, fibrinogen protein levels were increased 2–5 fold (Figure 7A). Measuring fibrinogen signal against a standard curve of purified murine fibrinogen, normal quadriceps contained approximately 0.9 ng fibrinogen per µg of protein, while quadriceps in C26 cachexia contained 1.9 ng/µg (Figure 7B), a ∼2-fold increase. Normal liver contained 1.8 ng/µg fibrinogen, while liver in C26 cachexia contained 5.2 ng/µg fibrinogen, a ∼3-fold increase. Fibrinogen expression was also increased in quadriceps as well as liver in response to administration of IL-6 (Figure 7B), suggesting this may be a general response to conditions of high IL-6 and not limited to cancer.

Bottom Line: In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response.These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer.These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such that amino acids liberated by increased proteolysis in cachexia are synthesized into acute phase proteins and exported into the blood.

View Article: PubMed Central - PubMed

Affiliation: Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, United States of America.

ABSTRACT

Background: Cachexia, or weight loss despite adequate nutrition, significantly impairs quality of life and response to therapy in cancer patients. In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response. Acute phase proteins, including fibrinogen and serum amyloid A (SAA) are synthesized by hepatocytes in response to IL-6 as part of the innate immune response. To gain insight into the relationships among these observations, we studied mice with moderate and severe Colon-26 (C26)-carcinoma cachexia.

Methodology/principal findings: Moderate and severe C26 cachexia was associated with high serum IL-6 and IL-6 family cytokines and highly similar patterns of skeletal muscle gene expression. The top canonical pathways up-regulated in both were the complement/coagulation cascade, proteasome, MAPK signaling, and the IL-6 and STAT3 pathways. Cachexia was associated with increased muscle pY705-STAT3 and increased STAT3 localization in myonuclei. STAT3 target genes, including SOCS3 mRNA and acute phase response proteins, were highly induced in cachectic muscle. IL-6 treatment and STAT3 activation both also induced fibrinogen in cultured C2C12 myotubes. Quantitation of muscle versus liver fibrinogen and SAA protein levels indicates that muscle contributes a large fraction of serum acute phase proteins in cancer.

Conclusions/significance: These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer. Through IL-6/STAT3 activation, skeletal muscle is induced to synthesize acute phase proteins, thus establishing a molecular link between the observations of high IL-6, increased acute phase response proteins and muscle wasting in cancer. These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such that amino acids liberated by increased proteolysis in cachexia are synthesized into acute phase proteins and exported into the blood.

Show MeSH
Related in: MedlinePlus