Gold Nanoparticle Based Fluorescence Resonance Energy Transfer Immunoassay for the Detection of the Histone Deacetylase Activity using a Fluorescent Peptide Probe

A novel platform for detection of histone deacetylase (HDAC) activity has been developed using a gold nanoparticle based fluorescence resonance energy transfer (FRET) immunoassay. This strategy combined the acetylated fluorescent peptide probe with the anti-acetyl antibody functionalized Au NPs to measure the deacetylation activity of histone deacetylase sirtuin2. Enzymatic deacetylation of the acetylated peptide substrate was detected by a gold nanoparticle labeled anti-acetyl peptide antibody with the formation of the immunocomplex resulting in energy transfer between the fluorescent dyes and the nanoparticles. Due to the highly efficient fluorescence quenching of the gold nanoparticles, the proposed method shows a low background and favorable sensitivity. In addition, this approach can be applied to the evaluation of HDAC inhibitor activity. The proposed platform should facilitate the development of new assays for HDAC activity and other histone modifications.     

Conformational analogues of Oxamflatin as histone deacetylase inhibitors

Conformational analogues of the hydroxamic acid Oxamflatin compounds, have been synthesised to enable evaluation of the impact of varying the linking section on histone deacetylase inhibition. Preliminary testing indicates treatment of leukaemia cells with each of the analogues leads to significant inhibition of histone deacetylase and reduction in cell growth and proliferation.     

Cyclic tetrapeptides bearing a sulfhydryl group potently inhibit histone deacetylases

New inhibitors of histone deacetylase (HDAC) containing a sulfhydryl group were designed on the basis of the corresponding hydroxamic acid (CHAP31) and FK228. Their disulfide dimers and hybrids exhibited potent HDAC inhibitory activity in vivo with potential as anticancer prodrugs. [structure: see text]     

Bis(4-hydroxybenzyl)sulfide: a sulfur compound inhibitor of histone deacetylase isolated from root extract of Pleuropterus ciliinervis

A sulfur compound, bis(4-hydroxybenzyl)sulfide (1) was isolated from the root extract of Pleuropterus ciliinervis. Its structure was elucidated using NMR spectroscopic techniques and mass spectrometric analysis. Compound 1 showed potent inhibitory activity in a histone deacetylase (HDAC) enzyme assay. It also exhibited growth inhibitory activity on five human tumor cell lines and more sensitive inhibitory activity on the MDA-MB-231 breast tumor cell line.     

Total syntheses of the histone deacetylase inhibitors largazole and 2-epi-largazole: application of N-heterocyclic carbene mediated acylations in complex molecule synthesis

Details of the evolution of strategies toward convergent assembly of the histone deacetylase inhibiting natural product largazole exploiting γ,δ-unsaturated-α,β-epoxy-aldehydes and a thiazole-thiazoline containing ω-amino-acid are described. The initial N-heterocyclic carbene mediated redox amidation exploying these two types of building blocks representing largazole's structural domains of distinct biosynthetic origin directly afforded the seco-acid of largazole. This was accomplished without any protecting groups resident upon either thioester bearing epoxy-aldehyde or the tetrapeptide. However, the ineffective production of largazole via the final macrolactonization led to an alternative intramolecular esterification/macrolactamization strategy employing the established two building blocks. This provided largazole along with its C2-epimer via an unexpected inversion of the α-stereocenter at the valine residue. The biological evaluation demonstrated that both largazole and 2-epi-largazole led to dose-dependent increases of acetylation of histone H3, indicating their potencies as class I histone deacetylase selective inhibitiors. Enhanced p21 expression was also induced by largazole and its C2 epimer. In addition, 2-epi-largazole displayed more potent activity than largazole in cell viability assays against PC-3 and LNCaP prostate cancer cell lines.     

Syntheses of amamistatin fragments and determination of their HDAC and antitumor activity

[reaction: see text] Amamistatins A and B are natural products found to have anti-proliferative effects against MCF-7, A549, and MKN45 human tumor cell lines (IC50 0.24-0.56 microM). It was proposed that their activity was due to histone deacetylase (HDAC) inhibition mediated by the N-formyl-N-hydroxy lysine moiety. Amamistatin B fragment analogs were synthesized and screened for biological activity. These compounds were modest HDAC inhibitors and showed antitumor activity against MCF-7 and PC-3 human tumor cells.     

Role of histone deacetylase activity in the developing lateral line neuromast of zebrafish larvae

Histone deacetylases are involved in many biological processes and have roles in regulating cell behaviors such as cell cycle entry, cell proliferation and apoptosis. However, the effect of histone deacetylases on the development of hair cells (HCs) has not been fully elucidated. In this study, we examined the influence of histone deacetylases on the early development of neuromasts in the lateral line of zebrafish. Hair cell development was evaluated by fluorescent immunostaining in the absence or presence of histone deacetylase inhibitors. Our results suggested that pharmacological inhibition of histone deacetylases with inhibitors, including trichostatin A, valproic acid and MS-275, reduced the numbers of both HCs and supporting cells in neuromasts. We also found that the treatment of zebrafish larvae with inhibitors caused accumulation of histone acetylation and suppressed proliferation of neuromast cells. Real-time PCR results showed that the expression of both p21 and p27 mRNA was increased following trichostatin A treatment and the increase in p53 mRNA was modest under the same conditions. However, the expression of p53 mRNA was significantly increased by treatment with a high concentration of trichostatin A. A high concentration of trichostatin A also led to increased cell death in neuromasts as detected in a TUNEL assay. Moreover, the nuclei of most of these pyknotic cells were immunohistochemically positive for cleaved caspase-3. These results suggest that histone deacetylase activity is involved in lateral line development in the zebrafish and might have a role in neuromast formation by altering cell proliferation through the expression of cell cycle regulatory proteins.     

Molecular insights into azumamide e histone deacetylases inhibitory activity

Azumamide E, a cyclotetrapeptide isolated from the sponge Mycale izuensis, is the most powerful carboxylic acid containing natural histone deacetylase (HDAC) inhibitor known to date. In this paper, we describe design and synthesis of two stereochemical variants of the natural product. These compounds have allowed us to clarify the influence of side chain topology on the HDAC-inhibitory activity. The present contribution also reveals the identity of the recognition pattern between azumamides and the histone deacetylase-like protein (HDLP) model receptor and reports the azumamide E unprecedented isoform selectivity on histone deacetylases class subtypes. From the present studies, a plausible model for the interaction of azumamides with the receptor binding pocket is derived, providing a framework for the rational design of new cyclotetrapeptide-based HDAC inhibitors as antitumor agents.     

Synthesis and activity of largazole analogues with linker and macrocycle modification

To characterize largazole's structural requirements for histone deacetylase (HDAC) inhibitory and antiproliferative activities, a series of analogues with modifications to the side chain or 16-membered macrocycle were prepared and biologically evaluated. Structure-activity relationships suggested that the four-atom linker between the macrocycle and octanoyl group in the side chain and the (S)-configuration at the C17 position are critical to repression of HDAC activity. However, the valine residue in the macrocycle can be replaced with alanine without significant loss of activity.     

Homology modeling,force field design,and free energy simulation studies to optimize the activities of histone deacetylase inhibitors

As an effort to develop therapeutics for cancer treatments, a number of effective histone deacetylase inhibitors with structural diversity have been discovered. To gain insight into optimizing the activity of an identified lead compound, a computational protocol sequentially involving homology modeling, docking experiments, molecular dynamics simulation, and free energy perturbation calculations was applied for rationalizing the relative activities of known histone deacetylase inhibitors. With the newly developed force field parameters for the coordination environment of the catalytic zinc ion in hand, the computational strategy proved to be successful in predicting the rank orders for 12 derivatives of three hydroxamate-based inhibitor scaffolds with indole amide, pyrrole, and sulfonamide moieties. The results showed that the free energy of an inhibitor in aqueous solution should be an important factor in determining the binding free energy. Hence, in order to enhance the inhibitory activity by adding or substituting a chemical group, the increased stabilization in solution due to the structural changes must be overcome by a stronger enzyme-inhibitor interaction. It was also found that to optimize inhibitor potency, the hydrophobic head of an inhibitor should be elongated or enlarged so that it can interact with Pro29 and His28 that are components of the flexible loop at the top of the active site.     

3D-QSAR Models of Anti-tumor Activity for Histone Deacetylase Inhibitors Containing Dihydropyridin-2-one

A 3D-QSAR study was conducted to analyze the anti-tumor activity(pHs, s = 1, 6) of dihydropyridin-2-one containing histone deacetylase inhibitor(DHDACi) to histone deacetylase(HDACs, s = 1, 6) by the comparative molecular field analysis(CoMFA) method. The predicting model was established based on the training set of 22 compounds, which was verified by the test set of 6 compounds containing template molecule. The results showed that the contributions of steric and electrostatic fields to pH_1 are 37.6% and 62.4%, and those to pH_6 are 44.6% and 55.4%, respectively. The coefficients of the cross-validation(R_(cv)~2) and the non cross-validation(R~2) are 0.574 and 0.947 for pH_1, and 0.488 and 0.884 for pH_6, respectively. The models were then used to predict the activities of the compounds for the training and testing sets. The results indicated that the models had strong stability and good predictability. Based on the 3D contour maps, several new potential inhibitors with higher anti-tumor activity were designed. However, the effectiveness of these potential inhibitors is still needed to be verified by the experimental results.     

Histone Deacetylase Inhibitory Activity and Antiproliferative Potential of New [6]-Shogaol Derivatives

Twenty newly synthesized derivatives of [6]-shogaol (4) were tested for inhibitory activity against histone deacetylases. All derivatives showed moderate to good histone deacetylase inhibition at 100 µM with a slightly lower potency than the lead compound. Most potent inhibitors among the derivatives were the pyrazole products, 5j and 5k, and the Michael adduct with pyridine 4c and benzothiazole 4d, with IC₅₀ values of 51, 65, 61 and 60 µM, respectively. They were further evaluated for isoform selectivity via a molecular docking study. Compound 4d showed the best selectivity towards HDAC3, whereas compound 5k showed the best selectivity towards HDAC2. The potential derivatives were tested on five cancer cell lines, including human cervical cancer (HeLa), human colon cancer (HCT116), human breast adenocarcinoma cancer (MCF-7), and cholangiocarcinoma (KKU100 and KKU-M213B) cells with MTT-based assay. The most active histone deacetylase inhibitor 5j exhibited the best antiproliferative activity against HeLa, HCT116, and MCF-7, with IC₅₀ values of 8.09, 9.65 and 11.57 µM, respectively, and a selective binding to HDAC1 based on molecular docking experiments. The results suggest that these compounds can be putative candidates for the development of anticancer drugs via inhibiting HDACs.     

基于组蛋白去乙酰化酶靶点的羟肟酸类化合物及其抗肿瘤活性研究进展

组蛋白去乙酰化酶（histone deacetylase, HDACs）是肿瘤治疗的靶点之一,组蛋白去乙酰化酶抑制剂（histone deacetylase inhibitor, HDACi）可通过多种机制发挥抗肿瘤作用,包括抑制肿瘤细胞活力、迁移、侵袭、血管生成、增殖、DNA修复和诱导细胞凋亡。本文对近年来以HDACs为单靶点和多靶点的羟肟酸类衍生物的合成及其抗肿瘤活性进行综述,并对此方面的发展趋势、应用前景进行展望。     

Synthesis of functionalized amides of 2-(arylamino)pyrimidine series

New amides of 2-(arylamino)pyrimidine series were synthesized with pharmacophoric fragments of tyrosine kinase and histone deacetylase inhibitors and functional groups providing chemosorption of compounds on nanocarriers.     

Target Design of Novel Histone Deacetylase 6 Selective Inhibitors with 2-Mercaptoquinazolinone as the Cap Moiety

Epigenetic alterations found in all human cancers are promising targets for anticancer therapy. In this sense, histone deacetylase inhibitors (HDACIs) are interesting anticancer agents that play an important role in the epigenetic regulation of cancer cells. Here, we report 15 novel hydroxamic acid-based histone deacetylase inhibitors with quinazolinone core structures. Five compounds exhibited antiproliferative activity with IC₅₀ values of 3.4–37.8 µM. Compound 8 with a 2-mercaptoquinazolinone cap moiety displayed the highest antiproliferative efficacy against MCF-7 cells. For the HDAC6 target selectivity study, compound 8 displayed an IC₅₀ value of 2.3 µM, which is 29.3 times higher than those of HDAC3, HDAC4, HDAC8, and HDAC11. Western blot assay proved that compound 8 strongly inhibited tubulin acetylation, a substrate of HDAC6. Compound 8 also displayed stronger inhibition activity against HDAC11 than the control drug Belinostat. The inhibitory mechanism of action of compound 8 on HDAC enzymes was then explored using molecular docking study. The data revealed a high binding affinity (−7.92 kcal/mol) of compound 8 toward HDAC6. In addition, dock pose analysis also proved that compound 8 might serve as a potent inhibitor of HDAC11.     

Total synthesis of spiruchostatin B, a potent histone deacetylase inhibitor, from a microorganism

The first total synthesis of spiruchostatin B, a potent histone deacetylase inhibitor, was achieved in a convergent manner; the synthesis established stereochemistry at the C5' position.     

一种香豆素荧光标记多肽的合成及应用

Sirtuin蛋白是一类称为依赖烟酰胺腺嘌呤二核苷酸（NAD）的组蛋白去乙酰化酶,共有7个成员,均是潜在的疾病治疗靶点。 然而,目前的荧光筛选方法,只适用于SIRT1~SIRT3。 因此,根据SIRT5的新酶活,设计、合成了针对SIRT5的荧光标记多肽（ISGASE(SuK) AMC）,并通过LC-MS和荧光检测证明了该荧光标记多肽能应用于SIRT5的活性筛选。     

Binding Free Energy (BFE) Calculations and Quantitative Structure–Activity Relationship (QSAR) Analysis of Schistosoma mansoni Histone Deacetylase 8 (smHDAC8) Inhibitors

Histone-modifying proteins have been identified as promising targets to treat several diseases including cancer and parasitic ailments. In silico methods have been incorporated within a variety of drug discovery programs to facilitate the identification and development of novel lead compounds. In this study, we explore the binding modes of a series of benzhydroxamates derivatives developed as histone deacetylase inhibitors of Schistosoma mansoni histone deacetylase (smHDAC) using molecular docking and binding free energy (BFE) calculations. The developed docking protocol was able to correctly reproduce the experimentally established binding modes of resolved smHDAC8–inhibitor complexes. However, as has been reported in former studies, the obtained docking scores weakly correlate with the experimentally determined activity of the studied inhibitors. Thus, the obtained docking poses were refined and rescored using the Amber software. From the computed protein–inhibitor BFE, different quantitative structure–activity relationship (QSAR) models could be developed and validated using several cross-validation techniques. Some of the generated QSAR models with good correlation could explain up to ~73% variance in activity within the studied training set molecules. The best performing models were subsequently tested on an external test set of newly designed and synthesized analogs. In vitro testing showed a good correlation between the predicted and experimentally observed IC₅₀ values. Thus, the generated models can be considered as interesting tools for the identification of novel smHDAC8 inhibitors.