Expression of different histone deacetylases and functional effects of histone deacetylase inhibitors in hepatocellular carcinoma

P Dietrich; K Freese; W Thasler; C Hellerbrand

doi:10.1055/s-0037-1612774

Zeitschrift für Gastroenterologie, Table of Contents

Z Gastroenterol 2018; 56(01): E2-E89
DOI: 10.1055/s-0037-1612774

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Georg Thieme Verlag KG Stuttgart · New York

Expression of different histone deacetylases and functional effects of histone deacetylase inhibitors in hepatocellular carcinoma

Authors

P Dietrich

¹Friedrich-Alexander University Erlangen-Nürnberg, Institute of Biochemistry, Erlangen
K Freese

¹Friedrich-Alexander University Erlangen-Nürnberg, Institute of Biochemistry, Erlangen
W Thasler

²Ludwig-Maximilians-University Munich, Biobank o.b. HTCR, Department of General Visceral- and Transplantation Surgery, Munich
C Hellerbrand

¹Friedrich-Alexander University Erlangen-Nürnberg, Institute of Biochemistry, Erlangen

³Comprehensive Cancer Center (CCC) Erlangen-EMN, Erlangen

Abstract

Full Text

Histone deacetylase (HDAC) comprise in humans currently 18 members divided in 4 classes. Application of HDAC inhibitors (HDACi) appears as promising therapeutic strategy in different types of cancer including hepatocellular cancer (HCC). However, detailed information about HDAC expression and functional mechanisms of HDACi-action in HCC are lacking.

The aim of this study was to perform a comprehensive analysis of the expression of HDAC classes I, II and IV and to functionally analyze the effect of 3 different HDACi in HCC cells.

Methods and Results:

Quantitative RT-PCR analysis revealed significantly increased expression of (i) HDAC 1/2/3/8 (class I); (ii) HDAC 4/5/6/9 (class IIa); (iii) HDAC 6/10 (class IIb) and (iiii) HDAC 11 (class IV) in 4 human HCC cell lines (Hep3B, HepG2, PLC, HuH7) and 11 human HCC tissues compared to primary human hepatocytes (PHH). Biochemical analysis showed significantly higher HDAC-activity in HCC cells compared to PHH. In human HCC samples, HDAC expression levels revealed significant correlations (over different HDAC-classes), i.e. it appeared that there are “high” and “low” HDAC-expressers. Next, we analyzed the toxic dose range of the HDACi suberoylanilide hydroxamic acid (SAHA), trichostatin A (TSA) and trapoxin (TPX) on HCC cells in vitro. SAHA irreversibly blocks the active zinc-binding site of HDAC enzymes and is already approved for the treatment of T-cell lymphoma. Also TPX is an irreversible inhibitor while TSA is a reversible HDACi. All 3 HDACi caused dose-dependent toxicity in HCC. At concentrations of 10µM (SAHA), 1µM (TSA) and 0.1µM (TPX) 100% of HCC cells died, while the same doses did not exhibit any toxicity in PHH. Next, we analyzed functional effects of the HDACi on HCC cells in sub-toxic doses. All 3 caused a dose-dependent reduction of proliferation as assessed by impedance based real time proliferation assays. Treatment with TSA and TPX induced a complete growth arrest, while SAHA inhibited proliferation only approximately 50%. Furthermore, all 3 HDACi reduced the migratory potential and clonogenicity of HCC cells in vitro but with different efficacy.

Conclusion:

HDACs are significantly increased in HCC and promote different facets of tumorigenicity of HCC cells in vitro. HDACi showed qualitatively similar but quantitatively different inhibitory effects on HCC cells in vitro, which may be exploit to develop more targeted therapeutic approaches. Interestingly, there is a general pattern of high and low HDAC-expression in human HCCtissues. Future studies need to unravel whether diagnostic analysis of HDAC-levels could predict tumor progression and/or response to therapeutic HDACi-application.