Functional characterization of human oncoprotein gankyrin in Zebrafish

Gankyrin is an oncoprotein containing seven ankyrin repeats that is overexpressed in hepatocellular carcinoma (HCC). Gankyrin binds to Mdm2, which results in accelerated ubiquitylation via degradation of p53, and it also plays an important role in cell proliferation. However, little is known about the relationships between p53 levels, cell proliferation, and gankyrin over-expression. In order to investigate the influence of gankyrin protein on p53 and Mdm2 in a zebrafish model, we injected human gankyrin (hgankyrin) containing expression vectors (pCS2-hgankyrin, pCS2-hgankyrin-EGFP) into zebrafish embryos. To measure p53 and Mdm2 expression in hgankyrin-injected embryos, RT-PCR, Northern blot and in-situ hybridization and BrdU immunostaining were used. In addition, to know the effect of hgankyrin on cell proliferation in vitro, cell viability assays such as MTT, trypan blue staining and RT-PCR following transfection of hgankyrin-containing vector into HEK 293 cell line were performed. In vivo results indicated that p53 mRNA levels decreased but those of Mdm2 were not decreased in the presence of hgankyrin. These results suggest that gankyrin downregulates p53 expression and not Mdm2 expression. In the study of cell proliferation, BrdU-positive cells were predominantly increased in the head and tail regions in hgankyrin-injected zebrafish. Additional in vitro studies using trypan blue staining and MTT assay showed that gankyrin-expressing HEK 293 cells proliferated at a faster rate, indicating that gankyrin promotes cell proliferation. Our results demonstrate that hgankyrin overexpression downregulates p53 expression and promotes cell proliferation in zebrafish. Gankyrin may play an important role in tumorigenesis via its effects on p53 and cell proliferation.     

Borinostats: solid-phase synthesis of carborane-capped histone deacetylase inhibitors with a tailor-made selectivity profile

The elevated expression of histone deacetylases (HDACs) in various tumor types renders their inhibition an attractive strategy for epigenetic therapeutics. One key issue in the development of improved HDAC inhibitors (HDACis) is the selectivity for single HDAC isoforms over unspecific pan inhibition to minimize off-target toxicity. Utilizing the carborane moiety as a fine-tuning pharmacophore, we herein present a robust solid phase synthetic approach towards tailor-made HDACis meeting both ends of the selectivity spectrum, namely pan inhibition and highly selective HDAC6 inhibition.

This work describes a versatile solid phase synthesis of carborane-capped histone deacetylase inhibitors with a tunable selectivity profile and synergistic anticancer activity with bortezomib.     

环肽类组蛋白去乙酰化酶抑制剂

组蛋白乙酰化转移酶(HAT)和组蛋白去乙酰化酶(HDAC)调节组蛋白乙酰化程度，HDAC在基因表达和染色体形成等方面起着重要的调节作用。HDAC抑制剂能够引起肿瘤细胞生长停滞、诱导肿瘤细胞分化和调亡。通过对各种HDAC抑制剂结构及作用机制的研究有助于该类药物在临床上的应用和拓宽癌症治疗的适用范围。本文概述了近年来天然及合成的环肽类组蛋白去乙酰化酶抑制剂的研究进展。     

分子信标用于p53 mRNA的体外定量检测

根据p53基因的序列设计并合成了能特异性检测p53 mRNA的分子信标(MB), 发展了一种快速定量测定细胞内总RNA提取物中p53 mRNA的方法. 采用鼻咽癌(CNE2)细胞系和经RNA干扰技术降低p53基因表达的CNE2-p53RNAi细胞系, 抽提总RNA并用MB检测, 验证了MB的检测对象是p53 mRNA. 将该方法应用于多种肿瘤细胞内p53基因表达水平的分析, 表达变化趋势与经典的mRNA分析方法RT-PCR检测结果相符. 在此基础上, 用MB对5-氟尿嘧啶(5-Fu)处理的肺腺癌细胞(A549)进行了p53 mRNA的体外定量检测, 结果表明采用MB能够快速地获知该药物对细胞内p53 mRNA表达影响的信息.     

Selective synthesis and utility of one tripyrrolic compound and its intermediates

Highly selective syntheses of tri(2,4-dimethyl-3-carbethoxypyrrolyl)-methane 8 and its dipyrrolic intermediate 6 and pyrrolic one 1 are described based on the successful correction of the wrong process for 1 in literature. Tripyrrolic compounds have attracted much attention recently and been developed in diverse fields. 1 was the key intermediate for some tyrosine kinase inhibitors, including newly-launched Sutent, and most recently we have found 6 was also synthetically useful in the synthesis of 11 that has been discovered as a novel histone deacetylases (HDAC) inhibitor with an IC(50) value of about 1 microM in our assessments and represents a promising lead for the development of more potent histone deacetylase inhibitors (HDACIs).     

HDAC对接研究:苯甲酰胺类抑制剂结合方式推测

通过计算机模拟的对接过程研究，发现了MS-275— 一种苯甲酰胺类的组蛋白去乙酰酶（HDAC）抑制剂与酶的可能的全新结合方式.这种结合方式与已经阐明的组蛋白去乙酰酶类似蛋白（HDLP）与曲古柳菌素A(trichostatin A, TSA)和suberoylanilide hydroxamic acid(SAHA)形成的复合物晶体结构中配体与酶的作用方式完全不同.从对接结果看，MS-275的作用靶点在酶活性口袋的最狭窄部位，而不是直接作用于锌离子.这似乎能够解释MS-275的低毒性特点，并且为设计和筛选全新的HDAC抑制剂提供了新思路.     

Combined inhibition of HDAC and DNMT1 induces p85α/MEKmediated cell cycle arrest by dual target inhibitor 208 in U937 cells

Herein we reported an efficient dual DNMT and HDAC inhibitor 208 with great antiproliferative activity against U937 cells. Further studies revealed 208 affected the whole proteome profile and could induce G1 cell cycle arrest and apoptosis in U937 cells through upregulating CDK inhibitor p16 and downregulating cyclin-dependent kinases and their activators.     

Structural biasing elements for in-cell histone deacetylase paralog selectivity

We use the structural dissection of two 1,3-dioxanes with in-cell histone deacetylase (HDAC) paralog selectivity to identify key elements for selective HDAC inhibitors. We demonstrate that o-aminoanilides are inactive toward HDAC6 while apparently inhibiting deacetylases that act upon histone substrates. This finding has important clinical implications for the development of HDAC inhibitor-based treatments that do not interfere with microtubule dynamics associated with HDAC6. We also show that suberoylanilide hydroxamic acid (SAHA) alone is a nonparalog-selective HDAC inhibitor and that the 1,3-dioxane diversity appended to SAHA is essential for HDAC6 paralog selectivity.     

Inhibition of histone deacetylase 3 protects beta cells from cytokine-induced apoptosis

Cytokine-induced beta-cell apoptosis is important to the etiology of type-1 diabetes. Although previous reports have shown that general inhibitors of histone deacetylase (HDAC) activity, such as suberoylanilide hydroxamic acid and trichostatin A, can partially prevent beta-cell death, they do not fully restore beta-cell function. To understand HDAC isoform selectivity in beta cells, we measured the cellular effects of 11 structurally diverse HDAC inhibitors on cytokine-induced apoptosis in the rat INS-1E cell line. All 11 compounds restored ATP levels and reduced nitrite secretion. However, caspase-3 activity was reduced only by MS-275 and CI-994, both of which target HDAC1, 2, and 3. Importantly, both MS-275 and genetic knockdown of Hdac3 alone were sufficient to restore glucose-stimulated insulin secretion in the presence of cytokines. These results suggest that HDAC3-selective inhibitors may be effective in preventing cytokine-induced beta-cell apoptosis.     

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.     

Polymer-assisted, multi-step solution phase synthesis and biological screening of histone deacetylase inhibitors

The polymer-assisted solution phase synthesis (PASP) of an array of histone deacetylase (HDAc) inhibitors is described. HDAc inhibitors have considerable potential as new anti-proliferative agents. Selected compounds were shown to inhibit both human endothelial cell proliferation, and the formation of tubules (neovascularisation) in an in vitro model of angiogenesis.     

Targeting glycosylation pathways and the cell cycle: sugar-dependent activity of butyrate-carbohydrate cancer prodrugs

Short-chain fatty acid (SCFA)-carbohydrate hybrid molecules that target both histone deacetylation and glycosylation pathways to achieve sugar-dependent activity against cancer cells are described in this article. Specifically, n-butyrate esters of N-acetyl-D-mannosamine (But4ManNAc, 1) induced apoptosis, whereas corresponding N-acetyl-D-glucosamine (But4GlcNAc, 2), D-mannose (But5Man, 3), or glycerol (tributryin, 4) derivatives only provided transient cell cycle arrest. Western blots, reporter gene assays, and cell cycle analysis established that n-butyrate, when delivered to cells via any carbohydrate scaffold, functioned as a histone deacetylase inhibitor (HDACi), upregulated p21WAF1/Cip1 expression, and inhibited proliferation. However, only 1, a compound that primed sialic acid biosynthesis and modulated the expression of a different set of genes compared to 3, ultimately killed the cells. These results demonstrate that the biological activity of butyrate can be tuned by sugars to improve its anticancer properties.     

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.