Sorafenib inhibits signal transducer and activator of transcription-3 signaling in cholangiocarcinoma cells by activating the phosphatase shatterproof 2

Authors

  • Boris R. A. Blechacz,

    1. Miles and Shirley Fiterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
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  • Rory L. Smoot,

    1. Miles and Shirley Fiterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
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  • Steven F. Bronk,

    1. Miles and Shirley Fiterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
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  • Nathan W. Werneburg,

    1. Miles and Shirley Fiterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
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  • Alphonse E. Sirica,

    1. Department of Pathology, Division of Cellular and Molecular Pathogenesis, Virginia Commonwealth University School of Medicine, Richmond, VA
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  • Gregory J. Gores

    Corresponding author
    1. Miles and Shirley Fiterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
    • College of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
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    • fax: 507-284-0762


  • Potential conflict of interest: Nothing to report.

Abstract

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway is one of the key signaling cascades in cholangiocarcinoma (CCA) cells, mediating their resistance to apoptosis. Our aim was to ascertain if sorafenib, a multikinase inhibitor, may also inhibit JAK/STAT signaling and, therefore, be efficacious for CCA. Sorafenib treatment of three human CCA cell lines resulted in Tyr705 phospho-STAT3 dephosphorylation. Similar results were obtained with the Raf-kinase inhibitor ZM336372, suggesting sorafenib promotes Tyr705 phospho-STAT3 dephosphorylation by inhibiting Raf-kinase activity. Sorafenib treatment enhanced an activating phosphorylation of the phosphatase SHP2. Consistent with this observation, small interfering RNA–mediated knockdown of phosphatase shatterproof 2 (SHP2) inhibited sorafenib-induced Tyr705 phospho-STAT3 dephosphorylation. Sorafenib treatment also decreased the expression of Mcl-1 messenger RNA and protein, a STAT3 transcriptional target, as well as sensitizing CCA cells to tumor necrosis factor–related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. In an orthotopic, syngeneic CCA model in rats, sorafenib displayed significant tumor suppression resulting in a survival benefit for treated animals. In this in vivo model, sorafenib also decreased tumor Tyr705 STAT3 phosphorylation and increased tumor cell apoptosis. Conclusion: Sorafenib accelerates STAT3 dephosphorylation by stimulating phosphatase SHP2 activity, sensitizes CCA cells to TRAIL-mediated apoptosis, and is therapeutic in a syngeneic rat, orthotopic CCA model that mimics human disease. (HEPATOLOGY 2009.)

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