Radiosensitizing Effect of a Phenylbutyrate-Derived Histone Deacetylase Inhibitor in Hepatocellular Carcinoma

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• 作者：Yen-Shen Lu ; M.D. ; Ph.D.^&lowast ; ; ^&Dagger ; ; ^§ ; ; Chia-Hung Chou ; Ph.D.^&lowast ; ; Kai-Yuan Tzen ; M.D.^&dagger ; ; Ming Gao ; Ph.D.^&lowast ; ; Ann-Lii Cheng ; M.D. ; Ph.D.^&lowast ; ; ^&Dagger ; ; ^§ ; ; ^¶ ; ; Samuel K. Kulp ; Ph.D.^鈥?/sup> ; Jason Chia-Hsien Cheng ; M.D. ; Ph.D.^&lowast ; ; ^§ ; ; ^¶ ; ; ^{jasoncheng@ntu.edu.tw}
• 关键词：Hepatocellular carcinoma ; Radiotherapy ; Histone deacetylase
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2012
• 期刊代码：136_03603016
• 类别：med
• 出版时间：1 June, 2012
• 卷：83
• 期：2
• 页码：e181-e189
• 文件大小：1356 K

摘要

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Purpose

Radiotherapy is integrated into the multimodal treatment of localized hepatocellular carcinoma (HCC) refractory to conventional treatment. Tumor control remains unsatisfactory and the sublethal effect associates with secondary spread. The use of an effective molecularly targeted agent in combination with radiotherapy is a potential therapeutic approach. Our aim was to assess the effect of combining a phenylbutyrate-derived histone deacetylase (HDAC) inhibitor, AR-42, with radiotherapy in m>in聽vitrom> and m>in聽vivom> models of human HCC.

Methods and Materials

Human HCC cell lines (Huh-7 and PLC-5) were used to evaluate the m>in聽vitrom> synergism of combining AR-42 with irradiation. Flow cytometry analyzed the cell cycle changes, whereas Western blot investigated the protein expressions after the combined treatment. Severe combined immunodeficient (SCID) mice bearing ectopic and orthotopic HCC xenografts were treated with AR-42 and/or radiotherapy for the m>in聽vivom> response.

Results

AR-42 significantly enhanced radiation-induced cell death by the inhibition of the DNA end-binding activity of Ku70, a highly versatile regulatory protein for DNA repair, telomere maintenance, and apoptosis. In ectopic xenografts of Huh-7 and PLC-5, pretreatment with AR-42 significantly enhanced the tumor-suppressive effect of radiotherapy by 48%and 66%, respectively. A similar combinatorial effect of AR-42 (10 and 25 mg/kg) and radiotherapy was observed in Huh-7 orthotopic model of tumor growth by 52%and 82%, respectively. This tumor suppression was associated with inhibition of intratumoral Ku70 activity as well as reductions in markers of HDAC activity and proliferation, and increased apoptosis.

Conclusion

AR-42 is a potent, orally bioavailable inhibitor of HDAC with therapeutic value as a radiosensitizer of HCC.