Sirtuin-6–dependent genetic and epigenetic alterations are associated with poor clinical outcome in hepatocellular carcinoma patients

Authors

  • Jens U. Marquardt,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
    2. Institute of Human Genetics, University Medical Center, Johannes Gutenberg University, Mainz, Germany
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    • These authors contributed equally to this work.

  • Kerstin Fischer,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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    • These authors contributed equally to this work.

  • Katharina Baus,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Anubha Kashyap,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Shengyun Ma,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Markus Krupp,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Matthias Linke,

    1. Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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  • Andreas Teufel,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Ulrich Zechner,

    1. Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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  • Dennis Strand,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Snorri S. Thorgeirsson,

    1. Institute of Human Genetics, University Medical Center, Johannes Gutenberg University, Mainz, Germany
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  • Peter R. Galle,

    1. First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Susanne Strand

    Corresponding author
    • First Department of Internal Medicine , University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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  • Potential conflict of interest: Nothing to report.

  • This study was supported by grants from the “Inneruniversitäre Forschungsförderung Stufe 1,” Johannes Gutenberg University, Mainz (to S. S.) and in part by the Forschungszentrum Immunologie, Imaging Core Facility, Johannes Gutenberg University, Mainz (to D. S.).

Address reprint requests to: Susanne Strand, Ph.D., First Department of Internal Medicine, Molecular Hepatology, University Medical Center, Johannes Gutenberg University Mainz, Obere Zahlbacherstrasse 63, 55131 Mainz, Germany. E-mail: sstrand@uni-mainz.de; fax: +49-6131-179963.

Abstract

Sirtuin 6 (SIRT6) is a member of the sirtuin family of NAD+–dependent deacetylases. Genetic deletion of Sirt6 in mice results in a severe degenerative phenotype with impaired liver function and premature death. The role of SIRT6 in development and progression of hepatocellular carcinoma is currently unknown. We first investigated SIRT6 expression in 153 primary human liver cancers and in normal and cirrhotic livers using microarray analysis. SIRT6 was significantly down-regulated in both cirrhotic livers and cancer. A Sirt6 knockout (KO) gene expression signature was generated from primary hepatoctyes isolated from 3-week-old Sirt6-deficient animals. Sirt6-deficient hepatocytes showed up-regulation of established hepatocellular carcinoma (HCC) biomarkers alpha-fetoprotein (Afp), insulin-like growth factor 2 (Igf2), H19, and glypican-3. Furthermore, decreased SIRT6 expression was observed in hepatoma cell lines that are known to be apoptosis-insensitive. Re-expression of SIRT6 in HepG2 cells increased apoptosis sensitivity to CD95-stimulation or chemotherapy treatment. Loss of Sirt6 was characterized by oncogenic changes, such as global hypomethylation, as well as metabolic changes, such as hypoglycemia and increased fat deposition. The hepatocyte-specific Sirt6-KO signature had a prognostic impact and was enriched in patients with poorly differentiated tumors with high AFP levels as well as recurrent disease. Finally, we demonstrated that the Sirt6-KO signature possessed a predictive value for tumors other than HCC (e.g., breast and lung cancer). Conclusion: Loss of SIRT6 induces epigenetic changes that may be relevant to chronic liver disease and HCC development. Down-regulation of SIRT6 and genes dysregulated by loss of SIRT6 possess oncogenic effects in hepatocarcinogenesis. Our data demonstrate that deficiency in one epigenetic regulator predisposes a tumorigenic phenotype that ultimately has relevance for outcome of HCC and other cancer patients. (Hepatology 2013;53:1054–1064)

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