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Loss of STAT5 causes liver fibrosis and cancer development through increased TGF-{beta} and STAT3 activation

Atsushi Hosui1, Akiko Kimura, Daisuke Yamaji

  • 1Laboratory of Genetics and Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. hosui@gh.med.osaka-u.ac.jp

The Journal of Experimental Medicine
|April 1, 2009
PubMed

Insights

Loss of signal transducer and activator of transcription (STAT) 5 in mice leads to increased transforming growth factor-beta (TGF-beta) and STAT3 activity, promoting liver fibrosis and cancer. Restoring STAT5 function prevents tumor development.

Area of Science:

  • Hepatology
  • Molecular Biology
  • Oncology

Background:

  • Hepatocellular carcinoma (HCC) development mechanisms are unclear.
  • Signal transducer and activator of transcription (STAT) 5 plays a role in liver health.
  • STAT5 deficiency is linked to liver disease progression.

Purpose of the Study:

  • To elucidate the molecular link between STAT5, transforming growth factor-beta (TGF-beta), and STAT3 in liver disease.
  • To investigate the role of STAT5 in regulating TGF-beta stability and activity.
  • To determine the in vivo significance of STAT5 in carbon tetrachloride (CCl4)-induced liver injury and tumorigenesis.

Main Methods:

  • Utilized liver-specific STAT5A/B-null (STAT5-LKO) and STAT5 N-terminus deleted (STAT5-DeltaN) mouse models.
  • Administered carbon tetrachloride (CCl4) to induce liver fibrosis and tumors.
  • Performed histological analyses, Western blotting, immunoprecipitation, and immunohistochemistry.

Main Results:

  • STAT5-LKO mice exhibited liver fibrosis, elevated TGF-beta protein levels, and increased STAT3 activity upon CCl4 treatment.
  • STAT5 deficiency enhanced mature TGF-beta protein stability without altering mRNA levels.
  • STAT5 directly binds to TGF-beta via its N-terminal domain, and its absence promotes CCl4-induced liver fibrosis but not tumors in STAT5-DeltaN mice.

Conclusions:

  • Loss of STAT5 leads to elevated TGF-beta levels and enhanced STAT3 activity.
  • A deregulated STAT5-TGF-beta-STAT3 signaling network contributes to chronic liver disease and hepatocellular carcinoma development.
  • STAT5's N-terminal domain is crucial for preventing CCl4-induced liver tumorigenesis.

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