Disparate Impact of Butyroyloxymethyl Diethylphosphate (AN-7), a Histone Deacetylase Inhibitor, and Doxorubicin in Mice Bearing a Mammary Tumor

The histone deacetylase inhibitor (HDACI) butyroyloxymethyl diethylphosphate (AN-7) synergizes the cytotoxic effect of doxorubicin (Dox) and anti-HER2 on mammary carcinoma cells while protecting normal cells against their insults. This study investigated the concomitant changes occurring in heart tissue and tumors of mice bearing a subcutaneous 4T1 mammary tumor following treatment with AN-7, Dox, or their combination. Dox or AN-7 alone led to inhibition of both tumor growth and lung metastases, whereas their combination significantly increased their anticancer efficacy and attenuated Dox- toxicity. Molecular analysis revealed that treatment with Dox, AN-7, and to a greater degree, AN-7 together with Dox increased tumor levels of γH2AX, the marker for DNA double-strand breaks and decreased the expression of Rad51, a protein needed for DNA repair. These events culminated in increased apoptosis, manifested by the appearance of cytochrome-c in the cytosol. In the myocardium, Dox-induced cardiomyopathy was associated with an increase in γH2AX expression and a reduction in Rad51 and MRE11 expression and increased apoptosis. The addition of AN-7 to the Dox treatment protected the heart from Dox insults as was manifested by a decrease in γH2AX levels, an increase in Rad51 and MRE11 expression, and a diminution of cytochrome-c release. Tumor fibrosis was high in untreated mice but diminished in Dox- and AN-7-treated mice and was almost abrogated in AN-7+Dox-treated mice. By contrast, in the myocardium, Dox alone induced a dramatic increase in fibrosis, and AN7+Dox attenuated it. The high expression levels of c-Kit, Ki-67, c-Myc, lo-FGF, and VEGF in 4T1 tumors were significantly reduced by Dox or AN-7 and further attenuated by AN-7+Dox. In the myocardium, Dox suppressed these markers, whereas AN-7+Dox restored their expression. In conclusion, the combination of AN-7 and Dox results in two beneficial effects, improved anticancer efficacy and cardioprotection

Valproic Acid Prodrug Affects Selective Markers, Augments Doxorubicin Anticancer Activity and Attenuates Its Toxicity in a Murine Model of Aggressive Breast Cancer

We studied the unique inhibitor of the histone deacetylases (HDAC) valproate-valpromide of acyclovir (AN446) that upon metabolic degradation release the HDAC inhibitor (HDACI) valproic acid (VPA). Among the HDAC inhibitors that we have tested, only AN446, and to a lesser extent VPA, synergized with doxorubicin (Dox) anti-cancer activity. Romidepsin (Rom) was additive and the other HDACIs tested were antagonistic. These findings led us to test and compare the anticancer activities of AN446, VPA, and Rom with and without Dox in the 4T1 triple-negative breast cancer murine model. A dose of 4 mg/kg once a week of Dox had no significant effect on tumor growth. Rom was toxic, and when added to Dox the toxicity intensified. AN446, AN446 + Dox, and VPA + Dox suppressed tumor growth. AN446 and AN446 + Dox were the best inhibitory treatments for tumor fibrosis, which promotes tumor growth and metastasis. Dox increased fibrosis in the heart and kidneys, disrupting their function. AN446 most effectively suppressed Dox-induced fibrosis in these organs and protected their function. AN446 and AN446 + Dox treatments were the most effective inhibitors of metastasis to the lungs, as measured by the gap area. Genes that control and regulate tumor growth, DNA damage and repair, reactive oxygen production, and generation of inflammation were examined as potential therapeutic targets. AN446 affected their expression in a tissue-dependent manner, resulting in augmenting the anticancer effect of Dox while reducing its toxicity. The specific therapeutic targets that emerged from this study are discussed

The Histone Deacetylase Inhibitor AN7, Attenuates Choroidal Neovascularization in a Mouse Model

Choroidal neovascularization (CNV) is a complication of age-related macular degeneration and a major contributing factor to vision loss. In this paper, we show that in a mouse model of laser-induced CNV, systemic administration of Butyroyloxymethyl-diethyl phosphate (AN7), a histone deacetylase inhibitor (HDACi), significantly reduced CNV area and vascular leakage, as measured by choroidal flatmounts and fluorescein angiography. CNV area reduction by systemic AN7 treatment was similar to that achieved by intravitreal bevacizumab treatment. The expression of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF-2), and the endothelial cells marker CD31, was lower in the AN7 treated group in comparison to the control group at the laser lesion site. In vitro, AN7 facilitated retinal pigmented epithelium (RPE) cells tight junctions’ integrity during hypoxia, by protecting the hexagonal pattern of ZO-1 protein in the cell borders, hence reducing RPE permeability. In conclusion, systemic AN7 should be further investigated as a possible effective treatment for CNV

The Therapeutic Potential of AN-7, a Novel Histone Deacetylase Inhibitor, for Treatment of Mycosis Fungoides/Sezary Syndrome Alone or with Doxorubicin.

The 2 histone deacetylase inhibitors (HDACIs) approved for the treatment of cutaneous T-cell lymphoma (CTCL) including mycosis fungoides/sezary syndrome (MF/SS), suberoylanilide hydroxamic acid (SAHA) and romidepsin, are associated with low rates of overall response and high rates of adverse effects. Data regarding combination treatments with HDACIs is sparse. Butyroyloxymethyl diethylphosphate (AN-7) is a novel HDACI, which was found to have selective anticancer activity in several cell lines and animal models. The aim of this study was to compare the anticancer effects of AN-7 and SAHA, either alone or combined with doxorubicin, on MF/SS cell lines and peripheral blood lymphocytes (PBL) from patients with Sezary syndrome (SPBL). MyLa cells, Hut78 cells, SPBL, and PBL from healthy normal individuals (NPBL) were exposed to the test drugs, and the findings were analyzed by a viability assay, an apoptosis assay, and Western blot. AN-7 was more selectively toxic to MyLa cells, Hut78 cells, and SPBL (relative to NPBL) than SAHA and also acted more rapidly. Both drugs induced apoptosis in MF/SS cell lines, SAHA had a greater effect on MyLa cell line, while AN-7 induced greater apoptosis in SPBL; both caused an accumulation of acetylated histone H3, but AN-7 was associated with earlier kinetics; and both caused a downregulation of the HDAC1 protein in MF/SS cell lines. AN-7 acted synergistically with doxorubicin in both MF/SS cell lines and SPBL, and antagonistically with doxorubicin in NPBL. By contrast, SAHA acted antagonistically with doxorubicin on MF/SS cell lines, SPBL, and NPBL, leaving <50% viable cells. In conclusion, AN-7 holds promise as a therapeutic agent in MF/SS and has several advantages over SAHA. Our data provide a rationale for combining AN-7, but not SAHA, with doxorubicin to induce the cell death in MF/SS

Effect of AN-7, DOX and their combinations on markers of proliferation and fibrosis.

<p>Sections of tumors and hearts were stained (DAB) for: (A) Ki-67; (B) c-Kit and both were counter stained with hematoxylin. The arrowhead marked the c-Kit positively staind cells. Bar = 200 µm, the 4-fold magnified picture in the insert was taken from the area indicated by the square. (C) Lysates samples, as described above, were resolved on 10% SDS gel and stained for c-Myc (left). The Mean±SE ratio of c-Myc/actin expression is shown (right). ^#p<0.05, as specified, vs. untreated control; *p<0.05, as specified, vs Dox. (D) Picrosirius red and fast-green for the visualization of interstitial fibrosis. Bar = 200 µm, the 2-fold magnified picture in the insert was taken from the area indicated by the square.</p

Effect of AN-7 on the activity and expression of cellular HDACs classes I and II.

<p>(A) The cells were exposed to AN-7 for 3 h in the presence of the HDAC fluorogenic substrate. The average % of HDAC activity as a function of 0–100 µM concentration of AN-7 of a representative experiment conducted in quadruplicates is shown. (B) The average IC₅₀±SE of AN-7 for each of the cell types is calculated from three independent experiments. (C) Lysates of cells were loaded (35 µg protein/well) on 10% SDS gels and were subjected to Western blot analysis. HDAC1, HDAC2, HDAC5 or actin were detected with the appropriate antibodies. (D) HDAC activity of three experiments (in triplicate) conducted with 4T1 (cancer) and H9C2 (non-cancer) cells treated with AN-7 (50 µM) as a single agent for a total of 3 h, 1 h prior to the addition of the fluorogenic substrate and 2 h in its presence; Dox (200 nM) as a single agent treatment, or with the combination AN-7+Dox where 50 µM AN-7 was added 1 h prior to the addition of Dox and the fluorogenic substrate and then incubated for an additional 2 h. (E) The viability of the cells treated as described in (D) was determined by a Hoechst assay after 23 or 24 h for cells treated with Dox. (F) Cells were treated with AN-7 (3 or 24 h), Dox (2 or 23 h) or AN-7 (3 or 24 h)+Dox (2 or 23 h), as described (D). The lysates of the cells were subjected to Western blot analysis as described (C).</p

Effect of Dox, AN-7, and AN-7+Dox in the 4T1 murine mammary carcinoma model.

<p>(A) In the preliminary experiment, female Balb/c mice carrying 75–180 mm³ subcutaneous 4T1 tumors were randomly divided into three groups (10 mice/group) and were injected ip once a week with either vehicle, 3 or 5 mg/kg Dox. Tumor volume was measured twice a week up to day 14 when the experiment was terminated (after 2 Dox treatments). Mean±SE of tumor volume was: *p<0.05, untreated vs. the other groups; #p<0.05, Dox 5 mg/kg vs. Dox 3 mg/kg. (B) Mean±SE of tumor weight and the ratio of heart-weight to body-weight (HW/BW, g/g), measured at the experiment termination point were: *p<0.01, Dox 5 mg/kg vs. all other groups. (C) In the pivotal experiment, the Percent Failure Free mice bearing 75–180 mm³ subcutaneous 4T1 tumors, was assessed by a Kaplan-Mier graph. The mice were assigned to the following treatments: saline vehicle ip (n = 7) or po (n = 7); ip Dox, 5 mg/kg once/week (n = 14); po AN-7, 50 mg/kg 3 times/week (n = 14); po AN-7+ip Dox (n = 14). The arrows on the x-axis indicate the point in time of the second and the third Dox treatment. (D) Mean±SE of heart-weight to body-weight ratios (HW/BW, g/g) at the above experiment end-point was ^#p<0.01, Dox 5 mg/kg vs. all other groups. (E) Tumor weight at the termination point (mean±SE) was: Dox 5 (total) represents the tumor weight of all the mice treated with 5 mg/kg Dox (n = 14), as measured at their individual end-points; Dox 5 (>21) represents the tumor weight of the mice (n = 5) treated with 5 mg/kg Dox and survived beyond day 21 of treatment. *p<0.02 all groups vs. untreated control; ^#p<0.05 AN-7+Dox vs. AN-7 or Dox 5 (total) or p<0.01 Dox 5 (>21). (F) Mean±SE of lung lesions for the various treatment groups is shown. *p<0.02, untreated vs. all treatment groups; ^#p<0.05, AN-7+Dox vs. AN-7 or vs. Dox.</p