In vivo PET imaging of histone deacetylases by 18F-suberoylanilide hydroxamic acid (18F-SAHA)

Histone deacetylases (HDACs) are a group of enzymes that modulate gene expression and cell state by deacetylation of both histone and non-histone proteins. A variety of HDAC inhibitors (HDACi) have already undergone clinical testing in cancer. Real-time in vivo imaging of HDACs and their inhibition would be invaluable; however, the development of appropriate imaging agents has remained a major challenge. Here, we describe the development and evaluation of (18)F-suberoylanilide hydroxamic acid ((18)F-SAHA 1a), a close analogue of the most clinically relevant HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). We demonstrate that 1a has near identical biochemical activity profiles to that of SAHA and report findings from pharmacokinetic studies. Using a murine ovarian cancer model, we likewise show that HDAC inhibitor target binding efficacy can be quantitated within 24 h of administration. 1a thus represents the first (18)F-positron emission tomography (PET) HDAC imaging agent, which also exhibits low nanomolar potency and is pharmacologically analogous to a clinically relevant HDAC inhibitor.     

Development of tetrahydroisoquinoline-based hydroxamic acid derivatives: potent histone deacetylase inhibitors with marked in vitro and in vivo antitumor activities

Inhibition of histone deacetylase (HDAC) results in growth arrest, differentiation, and apoptosis in nearly all tumor cell lines, promoting HDACs as promising targets for antitumor therapy. In our previous study we developed a novel series of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives as HDAC inhibitors (HDACi), among which compound 7d exhibited promising HDAC8 inhibitory and antiproliferative activities. Herein, we report the design and development of a new class of tetrahydroisoquinoline-bearing hydroxamic acid analogues as potential HDACi and anticancer agents. In vitro biological evaluation of these compounds showed improved HDAC8 inhibition (compounds 31a and 31b exhibited mid-nM IC(50) values against HDAC8) and potent growth inhibition in multiple tumor cell lines. Most importantly, compounds 25e, 34a, and 34b exhibited excellent in vivo anticancer activities in a human breast carcinoma (MDA-MB-231) xenograft model compared with suberoylanilide hydroxamic acid (SAHA), an approved HDACi. Collectively, our results indicate that tetrahydroisoquinoline bearing a hydroxamic acid is an excellent template to develop novel HDACi as potential anticancer agents.     

组蛋白去乙酰化酶抑制剂与加替沙星新缀合物的合成及抗肿瘤活性

目的 设计合成加替沙星-组蛋白去乙酰化酶抑制剂(histone deacetylase inhibitor, HDACi)缀合物，并探讨其抗肿瘤活性。方法 以第四代喹诺酮类药物加替沙星为原料，对其进行结构修饰，分别在其C-7哌嗪基和C-3位羧基引入辛二酰苯胺异羟肟酸(SAHA)单元，并采用HDACs试剂盒、微管蛋白试剂盒和MTT法对所合成的缀合物进行酶和抗肿瘤抑制活性测试。结果 合成了4个未见文献报道的新化合物10a~c和13，其结构均经过1H NMR、13C NMR和HRMS进行确证。初步的生物活性研究表明目标化合物能有效地抑制微管蛋白聚合和HDACs，并对5种肿瘤细胞有不同程度的抑制活性，其中SAHA类似物单元的侧链为6个亚甲基的缀合物10b和13对微管蛋白聚合和HDACs的抑制活性以及抗肿瘤活性强于其他衍生物。结论 将组蛋白去乙酰化酶抑制剂(HDACi)单元引入到加替沙星上，能提高其抗肿瘤活性。     

Development of N-Hydroxycinnamamide-Based Histone Deacetylase Inhibitors with an Indole-Containing Cap Group

相似文献   

The histone deacetylase inhibitor,trichostatin A,inhibits the development of 2,4-dinitrofluorobenzene-induced dermatitis in NC/Nga mice

Repetitive skin contact with a chemical hapten like 2,4-dinitrofluorobenzene (DNFB) evokes an atopic dermatitis (AD)-like dermatitis reaction in NC/Nga mice maintained under specific pathogen-free (SPF) conditions. The histone deacetylase (HDAC) inhibitor, trichostatin A (TSA), modulates the expression of several genes by inhibiting the activity of HDACs. Furthermore, TSA has been reported to suppress inflammatory cytokine expression and to induce T cell-suppression by increasing regulatory T cell (T reg cell) numbers. In addition, histone deacetylase inhibitors (HDACi) are currently undergoing clinical trials for the treatment of inflammatory disorders.     

Discovery of HDAC Inhibitors That Lack an Active Site Zn2+-Binding Functional Group

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Novel inhibitors of human histone deacetylases: design, synthesis, enzyme inhibition, and cancer cell growth inhibition of SAHA-based non-hydroxamates

To find novel non-hydroxamate histone deacetylase (HDAC) inhibitors, a series of compounds modeled after suberoylanilide hydroxamic acid (SAHA) was designed and synthesized. In this series, compound 7, in which the hydroxamic acid of SAHA is replaced by a thiol, was found to be as potent as SAHA, and optimization of this series led to the identification of HDAC inhibitors more potent than SAHA. In cancer cell growth inhibition assay, S-isobutyryl derivative 51 showed strong activity, and its potency was comparable to that of SAHA. The cancer cell growth inhibitory activity was verified to be the result of histone hyperacetylation and subsequent induction of p21(WAF1/CIP1) by Western blot analysis. Kinetical enzyme assay and molecular modeling suggest the thiol formed by enzymatic hydrolysis within the cell interacts with the zinc ion in the active site of HDACs.     

Antifibrotic activity of an inhibitor of histone deacetylases in DOCA-salt hypertensive rats

Background and purpose:

Histone deacetylases (HDACs) silence genes by deacetylating lysine residues in histones and other proteins. HDAC inhibitors represent a new class of compounds with anti-inflammatory activity. This study investigated whether treatment with a broad spectrum HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA), would prevent cardiac fibrosis, part of the cardiovascular remodelling in deoxycorticosterone acetate (DOCA)-salt rats.

Experimental approach:

Control and DOCA-salt rats were treated with SAHA (25 mg·kg⁻¹·day⁻¹ s.c.) for 32 days. Changes in cardiovascular structure and function were assessed by blood pressure in vivo and in Langendorff perfused hearts, ventricular papillary muscle and in aortic rings in vitro. Left ventricular collagen deposition was assessed by histology.

Key results:

Administration of SAHA to DOCA-salt rats attenuated the following parameters: the increased concentration of over 20 pro-inflammatory cytokines in plasma, increased inflammatory cell infiltration and interstitial collagen deposition, increased passive diastolic stiffness in perfused hearts, prolongation of action potential duration at 20% and 90% of repolarization in papillary muscle, development of left ventricular hypertrophy, systolic hypertension and changes in vascular dysfunction.

Conclusions and implications:

The HDAC inhibitor, SAHA, attenuated the cardiovascular remodelling associated with DOCA-salt hypertensive rats and improved cardiovascular structure and function, especially fibrosis, in the heart and blood vessels, possibly by suppressing inflammation. Control of cardiac histone or non-histone protein acetylation is a potential therapeutic approach to preventing cardiac remodelling, especially cardiac fibrosis.     

Targeting histone deacetylases for cancer therapy: Trends and challenges

Dysregulation of histone deacetylases(HDACs) is closely related to tumor development and progression. As promising anticancer targets, HDACs have gained a great deal of research interests and two decades of effort has led to the approval of five HDAC inhibitors(HDACis). However, currently traditional HDACis, although effective in approved indications, exhibit severe off-target toxicities and low sensitivities against solid tumors, which have urged the development of next-generation of HDACi. Thi...     

Contingent and non-contingent effects of low-dose ethanol on GABA neuron activity in the ventral tegmental area

Ventral tegmental area (VTA) GABA neurons appear to be critical regulators of mesocorticolimbic dopamine (DA) neurotransmission, which has been implicated in alcohol reward. The aim of this study was to evaluate the effects of low-dose “non-contingent” intravenous (IV) ethanol (0.01-0.1 g/kg) on VTA GABA neuron firing rate and synaptic responses, as well as VTA GABA neuron firing rate during low-dose “contingent” IV ethanol self-administration. Intravenous administration of 0.01-0.03 g/kg ethanol significantly increased VTA GABA neuron firing rate and afferent-evoked synaptic responses. In the runway self-administration paradigm, presentation of an olfactory cue (S+; almond extract) or no-cue (S−; no odor) in the Start box was paired with IV administration of low-dose ethanol (0.01 g/kg) or saline in the Target box. Runway excursion times decreased significantly in association during S+, and increased significantly during S− conditions. The firing rate of VTA GABA neurons markedly increased when rats received 0.01 g/kg IV ethanol in the Target box. VTA GABA neuron firing increased in the Start box of the runway in association with S+, but not S−. These findings demonstrate that VTA GABA neurons are activated by low-dose IV ethanol and that their firing rate increases in anticipation of ethanol reward.     

β-Arrestin-2 knockout prevents development of cellular μ-opioid receptor tolerance but does not affect opioid-withdrawal-related adaptations in single PAG neurons

BACKGROUND AND PURPOSE

Tolerance to the behavioural effects of morphine is blunted in β-arrestin-2 knockout mice, but opioid withdrawal is largely unaffected. The cellular mechanisms of tolerance have been studied in some neurons from β-arrestin-2 knockouts, but tolerance and withdrawal mechanisms have not been examined at the cellular level in periaqueductal grey (PAG) neurons, which are crucial for central tolerance and withdrawal phenomena.

EXPERIMENTAL APPROACH

μ-Opioid receptor (MOPr) inhibition of voltage-gated calcium channel currents (I_Ca) was examined by patch-clamp recordings from acutely dissociated PAG neurons from wild-type and β-arrestin-2 knockout mice treated chronically with morphine (CMT) or vehicle. Opioid withdrawal-induced activation of GABA transporter type 1 (GAT-1) currents was determined using perforated patch recordings from PAG neurons in brain slices.

KEY RESULTS

MOPr inhibition of I_Ca in PAG neurons was unaffected by β-arrestin-2 deletion. CMT impaired coupling of MOPrs to I_Ca in PAG neurons from wild-type mice, but this cellular tolerance was not observed in neurons from CMT β-arrestin-2 knockouts. However, β-arrestin-2 knockouts displayed similar opioid-withdrawal-induced activation of GAT-1 currents as wild-type PAG neurons.

CONCLUSIONS AND IMPLICATIONS

In β-arrestin-2 knockout mice, the central neurons involved in the anti-nociceptive actions of opioids also fail to develop cellular tolerance to opioids following chronic morphine. The results also provide the first cellular physiological evidence that opioid withdrawal is not disrupted by β-arrestin-2 deletion. However, the unaffected basal sensitivity to opioids in PAG neurons provides further evidence that changes in basal MOPr sensitivity cannot account for the enhanced acute nociceptive response to morphine reported in β-arrestin-2 knockouts.

LINKED ARTICLES

This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2     

Understanding the Role of Histone Deacetylase and their Inhibitors in Neurodegenerative Disorders: Current Targets and Future Perspective

Neurodegenerative diseases are a group of pathological conditions that cause motor inc-ordination (jerking movements), cognitive and memory impairments result from degeneration of neurons in a specific area of the brain. Oxidative stress, mitochondrial dysfunction, excitotoxicity, neuroinflammation, neurochemical imbalance and histone deacetylase enzymes (HDAC) are known to play a crucial role in neurodegeneration. HDAC is classified into four categories (class I, II, III and class IV) depending upon their location and functions. HDAC1 and 2 are involved in neurodegeneration, while HDAC3-11 and class III HDACs are beneficial as neuroprotective. HDACs are localized in different parts of the brain- HDAC1 (hippocampus and cortex), HDAC2 (nucleus), HDAC3, 4, 5, 7 and 9 (nucleus and cytoplasm), HDAC6 & HDAC7 (cytoplasm) and HDAC11 (Nucleus, cornus ammonis 1 and spinal cord). In pathological conditions, HDAC up-regulates glutamate, phosphorylation of tau, and glial fibrillary acidic proteins while down-regulating BDNF, Heat shock protein 70 and Gelsolin. Class III HDACs are divided into seven sub-classes (SIRT1-SIRT7). Sirtuins are localized in the different parts of the brain and neuron -Sirt1 (nucleus), Sirt2 (cortex, striatum, hippocampus and spinal cord), Sirt3 (mitochondria and cytoplasm), Sirt4, Sirt5 & Sirt6 (mitochondria), Sirt7 (nucleus) and Sirt8 (nucleolus). SIRTs (1, 3, 4, and 6) are involved in neuronal survival, proliferation and modulating stress response, and SIRT2 is associated with Parkinsonism, Huntington’s disease and Alzheimer’s disease, whereas SIRT6 is only associated with Alzheimer’s disease. In this critical review, we have discussed the mechanisms and therapeutic targets of HDACs that would be beneficial for the management of neurodegenerative disorders.     

Antidepressant-Like Properties of Novel HDAC6-Selective Inhibitors with Improved Brain Bioavailability

HDAC inhibitors have been reported to produce antidepressant and pro-cognitive effects in animal models, however, poor brain bioavailability or lack of isoform selectivity of current probes has limited our understanding of their mode of action. We report the characterization of novel pyrimidine hydroxyl amide small molecule inhibitors of HDAC6, brain bioavailable upon systemic administration. We show that two compounds in this family, ACY-738 and ACY-775, inhibit HDAC6 with low nanomolar potency and a selectivity of 60- to 1500-fold over class I HDACs. In contrast to tubastatin A, a reference HDAC6 inhibitor with similar potency and peripheral activity, but more limited brain bioavailability, ACY-738 and ACY-775 induce dramatic increases in α-tubulin acetylation in brain and stimulate mouse exploratory behaviors in novel, but not familiar environments. Interestingly, despite a lack of detectable effect on histone acetylation, we show that ACY-738 and ACY-775 share the antidepressant-like properties of other HDAC inhibitors, such as SAHA and MS-275, in the tail suspension test and social defeat paradigm. These effects of ACY-738 and ACY-775 are directly attributable to the inhibition of HDAC6 expressed centrally, as they are fully abrogated in mice with a neural-specific loss of function of HDAC6. Furthermore, administered in combination, a behaviorally inactive dose of ACY-738 markedly potentiates the anti-immobility activity of a subactive dose of the selective serotonin reuptake inhibitor citalopram. Our results validate new isoform-selective probes for in vivo pharmacological studies of HDAC6 in the CNS and reinforce the viability of this HDAC isoform as a potential target for antidepressant development.     

PPARγ Activation Attenuates Opioid Consumption and Modulates Mesolimbic Dopamine Transmission

PPARγ is one of the three isoforms identified for the peroxisome proliferator-activated receptors (PPARs) and is the receptor for the thiazolidinedione class of anti-diabetic medications including pioglitazone. PPARγ has been long studied for its role in adipogenesis and glucose metabolism, but the discovery of the localization in ventral tegmental area (VTA) neurons opens new vistas for a potential role in the regulation of reward processing and motivated behavior in drug addiction. Here, we demonstrate that activation of PPARγ by pioglitazone reduces the motivation for heroin and attenuates its rewarding properties. These effects are associated with a marked reduction of heroin-induced increase in phosphorylation of DARPP-32 protein in the nucleus accumbens (NAc) and with a marked and selective reduction of acute heroin-induced elevation of extracellular dopamine (DA) levels in the NAc shell, as measured by in vivo microdialysis. Through ex vivo electrophysiology in acute midbrain slices, we also show that stimulation of PPARγ attenuates opioid-induced excitation of VTA DA neurons via reduction of presynaptic GABA release from the rostromedial tegmental nucleus (RMTg). Consistent with this finding, site-specific microinjection of pioglitazone into the RMTg but not into the VTA reduced heroin taking. Our data illustrate that activation of PPARγ may represent a new pharmacotherapeutic option for the treatment of opioid addiction.     

Histone deacetylase inhibitors in the treatment of hematological malignancies

Histone deacetylases (HDACs) play a central role in the epigenetic regulation of gene expression. Aberrant activity of HDACs has been found in several human cancers leading to the development of HDAC inhibitors (HDACi) as anti-tumors drugs. In fact, over the last years, a number of HDACi have been evaluated in clinical trials; these drugs have the common ability to hyperacetylate both histone and non-histone targets, resulting in a variety of effects on both cancer cells and immune responses. Clinical trials of HDACi conducted in solid tumors and hematological malignancies have shown a better clinical efficacy of these drugs in hematological malignancies. In this review, will be highlighted the mechanisms of action underlying the clinical responses obtained with these drugs and the doubts regarding the use of HDACi in cancer therapy.     

用于筛选组蛋白去乙酰化酶抑制剂细胞模型的验证

目的验证已建立的组蛋白去乙酰化酶(HDAC)抑制剂筛选细胞模型,并采用该模型进行药物筛选。方法采用脂质体转染法将含有TA1和TA2启动子元件的荧光素酶报道基因真核表达载体pTA1-Luc和pTA2-Luc导入COS-7细胞,G418筛选获得稳定转染上述报告基因系统的细胞克隆。以特异性HDAC抑制剂缩酯环肽FK228,N-辛二酰苯胺异羟肟酸(SAHA)和曲古抑菌素A(TSA)为阳性对照,通过测定荧光素酶活性评估TA1和TA2启动子对HDAC抑制剂的反应;并采用此细胞模型对其他抗肿瘤药物和植物提取物进行初步筛选。结果稳定转染的COS-pTA1及COS-pTA2细胞对HDAC抑制剂具有良好的浓度依赖性(FK228:相关系数为0.7236;SAHA:相关系数为0.7997;TSA为相关系数为0.9815;P<0.01),其中COS-pTA1的特点是灵敏度高,可以有效避免因样品活性低而出现漏检。COS-pTA2细胞的特点是检测背景低,特异性强,可以有效排除假阳性的标本。两种细胞模型的联合筛选,可以鉴定具有HDAC抑制活性的化合物。结论该细胞模型可用于筛选具有HDAC抑制活性的先导化合物。