The histone-deacetylase inhibitor Trichostatin A blocks proliferation and triggers apoptotic programs in hepatoma cells.
OBJECTIVE
Effective treatment for hepatocellular carcinoma is urgently needed. The histone-deacetylase inhibitor Trichostatin A (TSA) was shown to induce apoptosis in non-hepatic cells at submicromolar concentrations. However, the effect of TSA on hepatoma cells is unknown.


METHODS
The hepatoma cells HepG2, MH1C1, Hepa1-6 and Hep1B as well as human fibroblasts (control cells) were exposed to TSA (10(-6) to 10(-9)M). Cell proliferation was assessed by measuring DNA-synthesis and cell numbers. Apoptosis was quantified by flow cytometry and by the TdT-mediated dUTP nick-end labeling method. Expression patterns of cell cycle- and/or apoptosis-associated p27, p21(cip/waf), bax, bcl-2, cyclin A and (pro)-caspase 3 were studied using quantitative Western blotting. Activation of caspase 3 was analyzed via a colorimetric assay.


RESULTS
10(-6)M TSA inhibited DNA-synthesis by 46% (HepG2) to 64% (MH1C1) after 24h, inducing a G(2)/M-phase arrest and apoptosis. TSA increased activation of caspase 3 and expression of cyclin A, p2l(cip/waf), bax and (pro)-caspase 3, while bcl-2 was downregulated. Human fibroblasts remained unaffected.


CONCLUSIONS
TSA inhibits hepatoma cell growth in vitro, which are otherwise particularly resistant to chemotherapy. Its anti-proliferative activity is paralleled by a comparable rate of apoptosis. TSA may be a promising agent for treatment of hepatocellular carcinoma in vivo.
Herold
Christoph
C
Department of Medicine I, University of Erlangen-Nuernberg, Krankenhausstrasse 12, 91054 Erlangen, Germany.
Ganslmayer
Marion
M
Ocker
Matthias
M
Hermann
Martin
M
Geerts
Albert
A
Hahn
Eckhart G
EG
Schuppan
Detlef
D
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D006528:Carcinoma, Hepatocellular; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D008113:Liver Neoplasms; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D050760:Cyclin-Dependent Kinase Inhibitor p27; C012589:trichostatin A; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases