Brief Article
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Aug 21, 2011; 17(31): 3623-3629
Published online Aug 21, 2011. doi: 10.3748/wjg.v17.i31.3623
Combined inhibitors of angiogenesis and histone deacetylase: Efficacy in rat hepatoma
Marion Ganslmayer, Annette Zimmermann, Steffen Zopf, Christoph Herold
Marion Ganslmayer, Steffen Zopf, Christoph Herold, Medical Department 1, University hospital Erlangen-Nuernberg, Ulmenweg 18, 91054 Erlangen, Germany
Annette Zimmermann, Department of Otolaryngology, University of Marburg, Baldingerstraβe 1, 35043 Marburg, Germany
Author contributions: Ganslmayer M, Zopf S and Herold C designed research; Ganslmayer M and Zimmermann A performed research; Ganslmayer M, Zimmermann A and Zopf S analyzed the data; and Ganslmayer M and Herold C wrote the paper.
Supported by The Schering AG, Berlin (Germany) which friendly provided PTK787/ZK222584 and MS-275
Correspondence to: Marion Ganslmayer, MD, Department of Internal Medicine 1, University hospital Erlangen-Nuernberg, Ulmenweg 18, D-91054 Erlangen, Germany.
Telephone: +49-9131-85450932 Fax: +49-9131-8535182
Received: December 31, 2010
Revised: March 7, 2011
Accepted: March 14, 2011
Published online: August 21, 2011

AIM: To evaluate the antitumoral effect of combined inhibitors of angiogenesis and histone deacetylases in an experimental rat hepatoma model.

METHODS: MH7777A hepatoma cells were injected into the liver of male Buffalo rats. After 7 d treatment with the vascular endothelial growth factor receptor antagonist PTK787/ZK222584 (PTK/ZK), the histone deacetylase inhibitor MS-275, tamoxifen (TAM) and/or retinoic acid was initiated (n≥ 8 animals/group). Natural tumor development was shown in untreated control groups (control 1 with n = 12, control 2 with n = 8). The control groups were initiated at different time points to demonstrate the stability of the hepatoma model. For documentation of possible side effects, we documented any change in body weight, loss of fur and diarrhea. After 21 d treatment, the rats were euthanized. Main target parameters were tumor size and metastasis rate. Additionally, immunohistochemistry for the proliferating cell nuclear antigen (PCNA) and TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay were performed.

RESULTS: The control groups developed large tumor nodules with extrahepatic tumor burden in the lung and abdominal organs (control 1: 6.18 cm3± 4.14 cm3 and control 2: 8.0 cm3± 4.44 cm3 28 d after tumor cell injection). The tumor volume did not differ significantly in the control groups (P = 0.13). As single agents MS-275 and PTK/ZK reduced tumor volume by 58.6% ± 2.6% and 48.7% ± 3.2% vs control group 1, which was significant only for MS-275 (P = 0.025). The combination of MS-275 and PTK/ZK induced a nearly complete and highly significant tumor shrinkage by 90.3% ± 1% (P = 0.005). Addition of TAM showed no further efficacy, while quadruple therapy with retinoic acid increased antitumoral efficacy (tumor reduction by 93 ± 1%) and side effects. PCNA positive cells were not significantly reduced by the single agents, while dual therapy (MS-275 and PTK/ZK) and quadruple therapy reduced the PCNA-positive cell fraction significantly by 9.1 and 20.6% vs control 1 (P < 0.05). The number of TUNEL-positive cells, markers for ongoing apoptosis, was increased significantly by the single agents (control 1: 6.9%, PTK/ZK: 11.4%, MS-275: 12.2% with P < 0.05 vs control 1). The fraction of TUNEL-positive cells was upregulated highly significantly by dual therapy (18.4%) and quadruple therapy (24.8%, P < 0.01 vs control 1). For the proliferating (PCNA positive) and apoptotic cell fraction, quadruple therapy was significantly superior to dual therapy (P = 0.01).

CONCLUSION: Combined PTK/ZK and MS-275 were highly effective in this hepatoma model. Quadruple therapy enhanced the effects microscopically, but not macroscopically. These results should be investigated further.

Keywords: PTK787, ZK222584, MS-275, Hepatocellular carcinoma, Histone deacetylase inhibitor