在治疗肿瘤领域中组蛋白去乙酰化酶抑制剂的研究进展

近年来在治疗肿瘤领域中组蛋白去乙酰化酶（HDAC）抑制剂的研究已成为热点。组蛋白乙酰化转移酶（HAT）与组蛋白去乙酰化酶（HDAC）之间保持的动态平衡调控着有序的基因表达, HDAC表达过度造成乙酰化的失衡会形成肿瘤,而HDAC抑制剂可诱导肿瘤细胞分化、细胞周期停滞和凋亡,抑制肿瘤的生成。HDAC抑制剂是很有前途的新型癌症靶向治疗药物。本文将重点阐述HDAC抑制剂的作用机制以及在肿瘤治疗领域中的研究进展。     

组蛋白去乙酰化酶抑制剂的研究进展

表观遗传学是目前遗传学研究的热点,而肿瘤的发生与表观遗传学关系密切.表观遗传修饰中组蛋白乙酰化酶(HAT)和组蛋白去乙酰化酶(HDAC)之间的动态平衡控制着染色质结构和基因表达.HDAC抑制剂作为新一代潜在靶向抗肿瘤药物,为国内外药学研究的热点.本文综述HDAC抑制剂的作用机制及临床研究进展.     

组蛋白去乙酰化酶抑制剂抗肿瘤临床研究进展

综述了近年来组蛋白去乙酰化酶(HDAC)抑制剂作为抗肿瘤药的临床研究进展。组蛋白去乙酰化酶抑制剂可以引导肿瘤细胞生长停滞、分化和凋亡,是很有前途的癌症治疗药物。目前,超过十多种组蛋白去乙酰化酶抑制剂作为治疗血液肿瘤和恶性实体瘤药物,有上百个临床试验正在进行中。     

肺癌患者外周血中单个核细胞HDAC活性的研究

目的:探讨肺癌患者外周血液单个核细胞和中性粒细胞中组蛋白去乙酰化酶(HDAC)的活性及临床意义。方法:采用酶标法,以健康人作对照,分别测定健康人和肺癌患者静脉血液外周单个核细胞及中性粒细胞中HDAC的活性。结果:健康人外周血液中单个核细胞中HDAC活性为(484±90AFU/μg),肺癌患者外周血液单个核细胞中HDAC活性为(4922±552AFU/μg),明显高于健康对照,两者相比有显著性差异(P<0.01);而中性粒细胞中HDAC活性无显著差异(P>0.05)。结论:肺癌患者外周静脉血液的单个核细胞HDAC活性增加,外周血单个核细胞HDAC活性有可能成为一种肿瘤筛选的标志物。     

以组蛋白去乙酰化酶为靶标的抗癌药物研发进展

基因表达的精确控制是细胞增殖分化和器官正常生长和发育的基础。基因转录和激活程序依赖于组蛋白乙酰化酶(histone acetylase，HAT)和组蛋白去乙酰化酶(histone deacetylase，HDAC)的协同作用。当HDAC过度表达并被转录因子募集，就会导致特定基因的不正常抑制，从而导致癌症及其他疾病。目前以HDAC作为抗癌靶点的研究方兴未艾，现综述HDAC类似蛋白(HDLP)的晶体结构和当前存在的HDAC抑制剂的作用机制、结构种类、研发状况和构效关系，以及新的HDAC抑制剂CS055的研发策略。     

组蛋白去乙酰化酶抑制剂抗肿瘤机制研究进展

肿瘤是威胁人类身体健康严重疾病之一,传统抗肿瘤药物因为选择性差而容易引起比较严重的毒副作用。随着近些年来临床医学研究水平的不断提高,有关肿瘤致病与发病机制的相关基本过程也逐渐被阐明,新型的抗肿瘤药物组蛋白去乙酰化酶（HDAC）抑制剂在临床中广泛应用开来。HDAC抑制剂能够作用于患者的肿瘤细胞,使肿瘤细胞的增殖受抑制,诱导肿瘤细胞凋亡,具有非常高的临床应用价值。本文就HDAC抑制剂在抗肿瘤方面所取得的效果以及药用机制等问题做了相关描述,供相关人员做参考。     

组蛋白去乙酰化酶6的结构、功能及选择性抑制剂的研究进展

组蛋白去乙酰化酶6(HDAC6)是组蛋白去乙酰化酶家族中独具特色的一员。该酶具有两个去乙酰化功能区,可特异性催化非组蛋白底物,参与并调节众多生理或病理进程。目前已报道的选择性HDAC6抑制剂结构种类较多,有的正处于临床试验阶段。本文将对HDAC6的结构、功能及其选择性抑制剂的研究进展进行综述。     

HDAC3在结肠癌组织中的表达及其临床病理相关性

目的探讨人结肠癌组织中组蛋白去乙酰化酶3(HDAC3)表达与临床病理特性的相关性。方法应用实时荧光定量PCR法和Western blot分别检测30例人结肠癌(A组)及其癌旁组织(B组)中HDAC3 mRNA和蛋白表达;另取5例正常结肠组织作为对照(C组)。用免疫组织化学方法检测高、中、低分化(各30例)结肠癌术后组织中HDAC3的表达水平。分析其表达与结肠癌临床病理学指标的关系。结果 A组HDAC3mRNA表达高于B组(5.91±3.70vs.3.22±2.63)(P<0.01)。A组HDAC3蛋白表达明显高于B、C组(0.90±0.16vs.0.28±0.15、0.06±0.01)(P<0.05)。90例结肠癌组织中HDAC3蛋白表达阳性率为78%,HDAC3表达强度与患者年龄、TNM分期和淋巴结转移密切相关(P<0.05)。结论 HDAC3高表达可能是结肠癌的特征之一,在结肠癌的侵袭力及淋巴结转移中起一定的作用。HDAC3可能成为诊断和判断预后的指标之一。     

组蛋白去乙酰化酶抑制剂恩替诺特

组蛋白去乙酰化酶(HDAC)是一类对染色质结构修饰和基因表达调控起重要作用的蛋白酶。因HDAC具有转录抑制功能,被视为是一类新兴的癌症药物靶点。HDAC过度表达影响包括乳腺癌在内的一些癌症的进程。抑制HDAC的表达或活性能够为治疗癌症提供新策略。恩替诺特是一种口服合成的苯甲酰胺衍生物类HDAC抑制剂,很有潜力成为抗癌药物,特别是乳腺癌治疗药物。多项临床试验研究表明恩替诺特具有安全性和有效性。     

食管鳞癌组织中组蛋白去乙酰化酶2的表达及临床意义

目的探讨组蛋白去乙酰化酶2(HDAC2)在食管鳞癌组织中的表达及其临床意义。方法应用实时荧光定量PCR及Western blot法检测30例配对人食管鳞癌(A组)和癌旁组织(C组)中HDAC2蛋白及其mRNA的表达。免疫组化方法检测90例(B组)食管鳞癌组织中HDAC2的表达水平,分析其与临床和病理特性的相关性。结果 A组HDAC2蛋白及其mRNA表达量均显著高于C组(P<0.01)。免疫组化结果显示,B组HDAC2蛋白表达阳性率为79%(71/90),HDAC2表达强度与TNM分期和淋巴结转移相关(P<0.05),而与患者年龄、性别、肿瘤大小、肿瘤位置、病理学大体分型、浸润深度及分化程度无关(P>0.05)。结论 HDAC2高表达可能是食管鳞癌的特征之一,在一定程度上可以反映肿瘤的恶性程度,可作为判断食管鳞癌患者预后的指标。     

Structural and enzymatic parameters that determine alkyl dehydrogenation/hydroxylation of capsaicinoids by cytochrome p450 enzymes.

Previous studies on the metabolism of capsaicinoids, natural products isolated from chili peppers, demonstrated the production of unique macrocyclic, alkyl dehydrogenated, omega-, and omega-1-hydroxylated products. This study investigated the structural and enzymatic parameters that direct selective alkyl dehydrogenation and hydroxylation of capsaicinoids, using a variety of structurally related capsaicinoid analogs and cytochrome P450 (P450) enzymes. CYP2C9 preferentially catalyzed alkyl dehydrogenation, whereas CYP2E1 and 3A4 catalyzed omega- and omega-1-hydroxylation, respectively. Analysis of incubations containing various P450s and structural variants of capsaicin by liquid chromatography-tandem mass spectrometry demonstrated similarities in the rate of capsaicinoid metabolism, but marked differences in the metabolite profiles. Production of macrocyclic and omega-1-hydroxylated metabolites from the various capsaicinoids was dependent on the structure of the alkyl terminus and P450 enzyme. A tertiary carbon at the omega-1 position, coupled to an adjacent unsaturated bond at the omega-2,3 position, enhanced the formation of the macrocyclic and dehydrogenated metabolites and were requisite structural features for omega-1-hydroxylated product formation. Conversely, substrates lacking these structural features were efficiently oxidized to the omega-hydroxylated metabolite. These data were consistent with our hypothesis that metabolism of the alkyl portion of capsaicinoids was governed, in part, by the stability and propensity to form an intermediate radical and a carbocation, and a direct interaction between the alkyl terminus and the heme of many P450 enzymes. These results provided valuable insights into potential mechanisms by which P450s metabolize capsaicinoids and highlight critical chemical features that may also govern the metabolism of structurally related compounds including fatty acids, monoter-penes, and isoprenoids.     

Pharmacokinetic features of the antiparasitic macrocyclic lactones

The macrocyclic lactones have pharmacokinetic properties which enhance their use against endo- and ectoparasites in animals and man. The most consistent physico-chemical feature of the group which contributes to their kinetic characteristics is high lipid solubility. This appears to be necessary for their pharmacodynamic action as well as common kinetic features such as large volumes of distribution and the influence of body fat composition on their disposition. They are used in all domestic animal species and are undoubtedly influenced by the anatomical and physiological differences in these species, however body fat composition also appears to exert a major influence on distribution, metabolism and persistence between species and between breeds and individuals. A myriad of formulations have been developed to enhance the convenience of administration in the different domestic animals and the macrocyclic lactones are delivered orally, subcutaneously and topically to good effect. Lipid based excipients have been developed in "depot" formulations to extend the period of effective prevention of parasite re-infection. Subtle structural changes have been made to the macrocyclic lactone molecules to reduce distribution to the central nervous system and mammary gland, thus allowing use of some compounds such as selamectin (SLM) in "toxicity sensitive" breeds of collie dog which lack P-glycoprotein efflux systems in their central nervous systems and the use of eprinomectin (EPM) in dairy cattle with a nil-milk withdrawal period. Gender differences exist in the pharmacokinetics of these compounds which may be associated with body (fat) composition or metabolism. Feeding may also reduce the availability of macrocyclic lactones which bind particulate digestive material and parasitism may impact the kinetics of the drugs because parasitized animals have altered pathophysiological processes, especially in the gastro intestinal tract but also because of the impact which parasitism may have on the body condition (and fat deposition) in animals. The pharmacokinetics of macrocyclic lactones may be affected by coadministration with compounds which interfere with P-glycoprotein transporters and these interactions have been explored as possible mechanisms for enhancing the effectiveness of these antiparasitics. The objective of this article is to provide a comprehensive review of the pharmacokinetics of macrocyclic lactones and to interpret where that information may prove clinically useful.     

Comparative DNA cross-linking by activated pyrrolizidine alkaloids.

The toxicity and bioactivity of pyrrolizidine alkaloids (PAs), common constituents of hundreds of plant species, and in herbal remedies and folk medicines prepared thereof, are probably due to their ability to form DNA cross-linking. We investigated DNA cross-linking activity by chemically-activated PAs from four different structural classes in Madin-Darby bovine kidney (MDBK) cells and in pBR322 DNA. In cell culture, alpha,beta-unsaturated macrocyclic diester pyrroles dehydrosenecionine (DHSN), dehydroriddelliine (DHRD) and the saturated macrocyclic diester pyrrole dehydromonocrotaline (DHMO) were significantly more potent cross-linkers than the simple necine base (retronecine) and an N-oxide (indicine N-oxide; INO) as determined by alkaline elution. The proportion of total DNA cross-links that were proteinase K-resistant (DNA-DNA cross-links) induced by the various pyrroles ranged from 0.08 (DHRN) to 0.67 (DHSN). Those pyrroles that were potent cross-linkers of cellular DNA also cross-linked, in a dose-dependent manner, Bam HI-digested pBR322 DNA as assessed by a gel retardation assay. The possible functional relevance of pyrrole-DNA cross-links was determined by their ability to interrupt PCR amplification of a 1.129 kb segment of pBR322. Dehydrosenecionine completely inhibited amplification, while DHMO was of intermediate potency, while DHRN and INO had no effect. Taken together, these studies suggest that structural features, most notably the presence of a macrocyclic diester, confer potent cross-link activity to PAs. In any event, DNA-DNA cross-linking is probably biologically relevant as indicated by their interference with DNA replication.     

Treatment of MDR1 mutant dogs with macrocyclic lactones

P-glycoprotein, encoded by the multidrug resistance gene MDR1, is an ATP-driven drug efflux pump which is highly expressed at the blood-brain barrier of vertebrates. Drug efflux of macrocyclic lactones by P-glycoprotein is highly relevant for the therapeutic safety of macrocyclic lactones, as thereby GABA-gated chloride channels, which are confined to the central nervous system in vertebrates, are protected from high drug concentrations that otherwise would induce neurological toxicity. A 4-bp deletion mutation exists in the MDR1 gene of many dog breeds such as the Collie and the Australian Shepherd, which results in the expression of a non-functional P-glycoprotein and is associated with multiple drug sensitivity. Accordingly, dogs with homozygous MDR1 mutation are in general prone to neurotoxicity by macrocyclic lactones due to their increased brain penetration. Nevertheless, treatment of these dogs with macrocyclic lactones does not inevitably result in neurological symptoms, since, the safety of treatment highly depends on the treatment indication, dosage, route of application, and the individual compound used as outlined in this review. Whereas all available macrocyclic lactones can safely be administered to MDR1 mutant dogs at doses usually used for heartworm prevention, these dogs will experience neurological toxicity following a high dose regimen which is common for mange treatment in dogs. Here, we review and discuss the neurotoxicological potential of different macrocyclic lactones as well as their treatment options in MDR1 mutant dogs.     

Macrocyclic diacylglycerol-bis-lactones as conformationally constrained analogues of diacylglycerol-lactones. Interactions with protein kinase C

A series of macrocyclic diacylglycerol (DAG)-bis-lactones were investigated as extreme conformationally constrained analogues of DAG-lactones in order to seek more potent protein kinase C (PKC) ligands with higher binding affinities and less lipophilicity than previous compounds. The additional constraint achieved the desired objective as exemplified by the macrocyclic DAG-bis-lactone 57, which exhibited a 6-fold higher binding affinity for PKCalpha (K(i) = 6.07 nM) than the corresponding nonmacrocyclic 3-alkylidene DAG-lactone 6. A structure-activity relationship (SAR) analysis of the macrocyclic DAG-bis-lactones demonstrated a parabolic relationship between activity and lipophilicity, as well as a predilection for the Z-alkylidene isomers as the preferred ligands. Molecular docking studies revealed that macrocyclic DAG-bis-lactone 57 bound to the C1b domain of PKCalpha exclusively in the sn-1 binding mode in contrast to DAG-lactone 6, which showed both sn-1 and sn-2 binding modes. It is proposed that the high potency displayed by these macrocyclic DAG-bis-lactones results from a set of more favorable hydrogen bonding and hydrophobic interactions with PKCalpha as well as from a reduced entropy penalty due to conformational restriction.     

A novel macrocyclic polyamine cationic lipid containing an imidazolium salt group: synthesis, characterization and its transfection activity as a gene delivery vector

The synthesis and characterization of a novel macrocyclic polyamine cationic lipid containing an imidazolium salt group is reported. Its interaction with plasmid DNA was studied by gel electrophoresis and fluorescence quenching experiments. The transfection activity of target compound as a gene delivery vector was also investigated. The results showed that the synthesized macrocyclic polyamine cationic lipid has high binding and condensation ability of DNA under physiological conditions probably because of the cooperation effect of macrocyclic polyamine (Cyclen) and an imidazolium salt group. This novel lipid could transfer plasmid DNA into cell in in vitro experiment without the use of any extraneous agent.     

Macrocyclic inhibitors of beta-secretase: functional activity in an animal model

A macrocyclic inhibitor of beta-secretase was designed by covalently cross-linking the P1 and P3 side chains of an isophthalamide-based inhibitor. Macrocyclization resulted in significantly improved potency and physical properties when compared to the initial lead structures. More importantly, these macrocyclic inhibitors also displayed in vivo amyloid lowering when dosed in a murine model.     

Lipophilic 1,3-xylyl-21-crown-6 macrocyclic polyether 2-carboxylic acids as biological mimics of the ionophore antibiotics

Twelve lipophilic 1,3-xylyl-21-crown-6 macrocyclic polyether 2-carboxylic acids, two lariat ether 1,3-xylyl-21-crown-6 macrocyclic polyether 2-carboxylic acids, and two 1,3-xylyl-28-crown-8 macrocyclic polyether 2-carboxylic acids were synthesized and tested for in vitro antibacterial activity, in vitro stimulation of rumen propionic acid production, and in vivo anticoccidial activity in chickens. These are biological screens relevant to animal health areas where the ionophore antibiotics such as monensin have found application. While the parent structure 1 without lipophilic substituents was biologically inactive, the lipophilic macrocycles were active in the two in vitro tests but not against chicken coccidiosis. One compound was tested in cattle and was found to increase levels of propionic acid in the rumen fermentation. This effect is considered an important factor for increasing the efficiency of feed utilization in cattle exhibited by the ionophore antibiotic monensin. The alkali ion salts of these lipophilic macrocyclic polyether carboxylic acids are very soluble in organic solvents and insoluble in water. These compounds are proposed to act as ion-transport agents and functional mimics of the ionophore antibiotics in the biological systems described above.     

Structure-activity relationships for human estrogenic activity in zearalenone mycotoxins.

Zearalenones are estrogenic Fusarium mycotoxins consisting of a resorcinol moiety fused to a 14-member macrocyclic lactone. Using an improved MCF7 human breast cell proliferation assay, we have compared the estrogenicity of 17 chromatographically-homogeneous zearalenones. Both similarities and substantial differences from published results in intact animal systems were observed. Substantial human estrogenicity was retained even in analogs lacking hydroxylation on the aromatic and macrocyclic rings.