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Growth-hormone-induced signal transducer and activator of transcription 5 signaling causes gigantism, inflammation, and premature death but protects mice from aggressive liver cancer

Friedbichler, K. and Themanns, M. and Mueller, K. M. and Schlederer, M. and Kornfeld, J. W. and Terracciano, L. M. and Kozlov, A. V. and Haindl, S. and Kenner, L. and Kolbe, T. and Mueller, M. and Snibson, K. J. and Heim, M. H. and Moriggl, R.. (2012) Growth-hormone-induced signal transducer and activator of transcription 5 signaling causes gigantism, inflammation, and premature death but protects mice from aggressive liver cancer. Hepatology, Vol. 55, H. 3. pp. 941-952.

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Official URL: http://edoc.unibas.ch/dok/A6338527

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Abstract

Persistently high levels of growth hormone (GH) can cause liver cancer. GH activates multiple signal-transduction pathways, among them janus kinase (JAK) 2-signal transducer and activator of transcription (STAT) 5 (signal transducer and activator of transcription 5). Both hyperactivation and deletion of STAT5 in hepatocytes have been implicated in the development of hepatocellular carcinoma (HCC); nevertheless, the role of STAT5 in the development of HCC as a result of high GH levels remains enigmatic. Thus, we crossed a mouse model of gigantism and inflammatory liver cancer caused by hyperactivated GH signaling (GH(tg) ) to mice with hepatic deletion of STAT5 (STAT5(Deltahep) ). Unlike GH(tg) mice, GH(tg) STAT5(Deltahep) animals did not display gigantism. Moreover, the premature mortality, which was associated with chronic inflammation, as well as the pathologic alterations of hepatocytes observed in GH(tg) mice, were not observed in GH(tg) animals lacking STAT5. Strikingly, loss of hepatic STAT5 proteins led to enhanced HCC development in GH(tg) mice. Despite reduced chronic inflammation, GH(tg) STAT5(Deltahep) mice displayed earlier and more advanced HCC than GH(tg) animals. This may be attributed to the combination of increased peripheral lipolysis, hepatic lipid synthesis, loss of hepatoprotective mediators accompanied by aberrant activation of tumor-promoting c-JUN and STAT3 signaling cascades, and accumulation of DNA damage secondary to loss of cell-cycle control. Thus, HCC was never observed in STAT5(Deltahep) mice. CONCLUSION: As a result of their hepatoprotective functions, STAT5 proteins prevent progressive fatty liver disease and the formation of aggressive HCC in the setting of hyperactivated GH signaling. At the same time, they play a key role in controlling systemic inflammation and regulating organ and body size.
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Department of Biomedicine, University Hospital Basel > Hepatology Laboratory (Heim)
UniBasel Contributors:Heim, Markus H.
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Saunders
ISSN:0270-9139
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:10 Apr 2015 09:14
Deposited On:10 Apr 2015 09:14

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