Abstract 77: The HDAC inhibitory prodrug AN-7 reduces the toxicity of doxorubicin, anti-Her2 and radiation while augmenting their anticancer efficacy
Authors: Tarasenko Nataly , Cutts Suzanne M. , Lipsky Yoav , Boer Pnina , Nudelman Abraham , Fenig Eyal , Kessler-Icekson Gan-Ia , Phillips Don R. , Rephaeli Ada 
Published: June 2012

The histone deacetylase inhibitor (HDACI) butyroyloxymethyl diethylphosphate (AN-7), has been shown to possess anticancer activity in vitro and in vivo and to act in synergy with doxorubicin (Dox) in killing cancer cells while attenuating Dox-induced cardiotoxicity (Rephaeli et al., 2007). In this study we further explored the effect of AN-7 in combination with Dox, the antibody Ab-4 against Her2/neu receptor (anti-HER2) and radiation, on several cancer and normal cells. The cells studied were the murine mammary 4T1, human breast T47D and glioblastoma U251 cell lines, neonatal rat cardiomyocytes, cardiofibroblasts and astrocytes, and the immortalized cardiomyocyte cell line H9C2. Inhibition of the activity of HDAC class I and II in the cells was performed using a cell permeable fluorescent probe. In vivo, we tested the effect of AN-7, Dox and their combination (AN-7+Dox) on naïve or mammary tumor-bearing Balb-c mice and in in mice bearing glioma. Cell death, ROS production and changes in protein expression were evaluated. AN-7 in combination with Dox or anti-Her2 acted in synergy to induce cell death of human breast carcinoma cells T47D (with combination indices of 0.74 and 0.79, respectively). AN-7 also augmented radiation induced mortality of T47D and at the same time, it protected cardiomyocytes against the toxicity induced by either anti-HER2 or radiation. Additionally, AN-7 protected astrocytes against Dox-induced cytotoxicity. While SAHA inhibited to a similar extent the HDAC activity in normal astrocytes and cardiomyocytes, AN-7 selectively inhibited inhibited HDAC activity in glioblastoma and mammary carcinoma cell lines. Cell-type specific changes in the expression of proteins controlling survival, angiogenesis and inflammation by AN-7 or AN-7+Dox were observed in vitro and in vivo. In mice, the efficacy of SAHA and AN-7 was similar while AN-7 was significantly less toxic than SAHA (p&lt;0.02). The antineoplastic efficacy of Dox and AN-7+Dox was associated with reduction in tumor angiogenesis, proliferation and growth. However, the antineoplastic activity of Dox was associated with toxicity as was evident by lower survival rate and the reduction in the expression of pro-angiogenic factors and proliferating and c-kit positive cells in the heart of the Dox-treated mice. In comparison to Dox, AN-7 plus Dox treatment resulted not only in a greater anticancer efficacy, but also in the protection of the mice against Dox-induced toxicity. In summary, AN-7 augmented the anticancer activity of Dox, anti-HER2 and radiation and attenuated their toxicity. The effects of AN-7, Dox and their combination were preserved in vivo, indicating the potential benefit of AN-7 in combination with anticancer therapy for clinical use.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 77. doi:10.1158/1538-7445.AM2011-77