下调组蛋白赖氨酸特异性脱甲基酶1的表达引起人白血病Molt-4细胞的凋亡

目的观察LSD1基因对人类急性T淋巴母细胞性白血病Molt-4细胞增殖和凋亡的影响。方法设计并筛选出针对LSD1基因的最佳siRNA片段,将其转染入Molt-4细胞后,MTS法观察LSD1 siRNA对Molt-4细胞增殖的影响;流式细胞术分析细胞凋亡;Western blot检测LSD1 siRNA作用后组蛋白H3K4、H3K9甲基化及组蛋白H3乙酰化状态,以及p15、DNA甲基化酶1(DNMT1)和凋亡相关蛋白Bcl-2、procaspase-3的表达变化。结果沉默LSD1基因可抑制细胞增殖,LSD1 siRNA浓度为0、30、60、120 nmol·L~(-1)作用48 h后,Molt-4细胞的增殖率分别为(99.65±1.21)%、(83.02±1.69)%、(65.72±2.16)%、(41.15±2.23)%,差异具有统计学意义(P<0.05);LSD1 siRNA以60 nmol·L~(-1)的浓度转染细胞0、24、48、72 h,增殖率分别为(99.86±1.35)%、(65.72±2.16)%、(48.26±1.92)%、(37.86±1.66)%,P<0.05,提示LSD1 siRNA可以抑制Molt-4细胞的增殖。LSD1 siRNA 0、30、60、120 nmol·L~(-1)作用48 h后,细胞凋亡率分别为(3.35±1.26)%、(12.16±1.74)%、(32.74±2.47)%、(54.64±2.58)%,P<0.05,凋亡率随着LSD1 siRNA浓度的增加逐渐上升;同时出现凋亡相关蛋白Bcl-2、procaspase-3的表达下降;LSD1 siRNA抑制LSD1蛋白及LSD1 mRNA,上调组蛋白H3K4一甲基化、二甲基化及组蛋白H3的乙酰化水平,H3K4三甲基化、H3K9甲基化水平无明显变化;LSD1 siRNA下调DNA去甲基化酶DNMT1的表达,上调p15的表达。结论 LSD1 siRNA能抑制Molt-4细胞的增殖并诱导其凋亡,其机制可能与表观遗传学调控有关,有望成为白血病治疗的一个新的靶点。     

BIX-01294对Molt-4细胞增殖、凋亡及组蛋白甲基化的影响

目的观察甲基化转移酶G9a抑制剂BIX-01294对急性T淋巴细胞白血病Molt-4细胞增殖、凋亡及组蛋白甲基化的影响。方法 MTT法绘制细胞生长曲线,流式细胞仪检测细胞凋亡的变化;Western blot检测凋亡相关蛋白Caspase-3、Bcl-2、Bax、抑癌蛋白P15、DNA去甲基化酶DNMT1、组蛋白H3乙酰化、组蛋白H3K9单、双、三甲基化水平,H3K27单甲基化、双甲基化水平的变化。结果 BIX-01294可下调Bcl-2蛋白、上调Bax蛋白的表达,Caspase-3表达上调,诱导细胞凋亡,浓度为0、1、2、4μmol·L-1的BIX-01294作用Molt-4细胞24 h后,凋亡率分别为(5.54±1.35)%、(10.24±2.26)%、(32.28±3.26)%、(47.52±4.37)%(P<0.05),差异有统计学意义。BIX-01294抑制DNMT1表达,上调P15蛋白表达,抑制细胞的增殖;BIX-01294下调组蛋白H3K9、H3K27单甲基化和二甲基化水平,而组蛋白H3乙酰化及H3K9三甲基化水平无明显改变。结论 BIX-01294通过抑制G9a的活性,下调H3K9、H3K27单甲基化、二甲基化水平,抑制DNMT1,使上调P15蛋白,最终抑制Molt-4细胞增殖,并诱导细胞凋亡。     

HDAC抑制剂及其联合PI3K抑制剂抗肿瘤研究进展

组蛋白去乙酰化酶(histone deacetylase, HDAC)通常异常过表达,导致肿瘤抑制基因的转录抑制。作为具有巨大潜力的抗癌药物,组蛋白去乙酰化酶抑制剂(histone deacetylase inhibitors, HDIs)可以通过调节核小体结构,抑制HDAC活性,调控抑癌基因表达而发挥抗肿瘤效应。目前,已上市的5个HDAC抑制剂适应症局限于外周T细胞淋巴瘤和皮肤T细胞淋巴瘤,而在实体瘤方面,大多数作为单一药物使用的HDAC抑制剂未能得到有效的治疗效果。磷脂酰肌醇3-激酶(phosphoinositide 3-kinase, PI3K)是PI3K-AKT-mTOR信号通路的起始节点,在肿瘤细胞的增殖、迁移、侵袭、分化等过程中起着十分重要的作用,该通路的异常激活与肿瘤的发生发展有着密切关系,将HDAC抑制剂和PI3K抑制剂的联合使用以及HDAC/PI3K双靶点抑制剂能够改善单独用药时存在的问题。本综述介绍了具有代表性的HDIs和PI3K抑制剂,以及HDAC/PI3K抑制剂联用及双靶点抑制剂的抗肿瘤临床和临床前研究进展。     

沉默DNMT1基因对Molt-4细胞增殖、凋亡及组蛋白调控的影响

目的探讨siRNA沉默DNMT1基因对人急性T淋巴细胞性白血病Molt-4细胞增殖、凋亡及组蛋白调控的影响。方法将DNMT1特异性siRNA经LipofectamineTM2000转染Molt-4细胞后,应用RT-PCR检测Molt-4细胞DNMT1 mRNA表达,MTT法绘制细胞生长曲线;流式细胞术分析细胞凋亡。Western blot检测Bcl-2、procaspase-3、P15蛋白表达以及组蛋白甲基化、乙酰化状态的改变。结果 DNMT1 siRNA可沉默DNMT1基因的表达,并呈现浓度依赖性;抑制Molt-4细胞增殖,诱导细胞凋亡。经0、30、60、120 nmol·L-1DNMT1 siRNA作用24h后,细胞凋亡率分别为(4.27±1.42)%,(15.25±1.54)%,(35.63±2.54)%,(66.27±3.02)%,差异具有统计学意义(P<0.05)。DNMT1 siRNA可上调P15的表达;下调Bcl-2、procaspase-3的表达,下调组蛋白H3K9甲基化水平,上调组蛋白H3K4的甲基化水平,而组蛋白H3乙酰化水平无明显变化。结论 DNMT1 siRNA可以有效地抑制Molt-4细胞中DNMT1的表达,下调组蛋白H3K9甲基化水平,上调组蛋白H3K4的甲基化水平,从而抑制细胞增殖和诱导细胞凋亡。     

姜黄素诱导Raji、HL-60和K562组蛋白乙酰化的研究

目的研究姜黄素对淋巴瘤细胞系Raji细胞的抑制增殖作用,并在组蛋白乙酰化/去乙酰化水平对其抗肿瘤机制进行探讨。方法MTT法检测不同浓度姜黄素、TSA作用于Raji细胞的抑制增殖率。以TSA处理后的细胞为阳性对照,免疫组化法定量分析及免疫荧光流式细胞化学定量检测姜黄素作用后Raji、HL-60、K562细胞的组蛋白乙酰化H3水平。结果姜黄素抑制Raji细胞增殖,并呈时间剂量依赖性;25μmol.L-1姜黄素可致Raji、HL-60、K562细胞的乙酰化H3水平增加(P<0.05),50μmol.L-1姜黄素的诱导作用增强(P<0.01)。结论姜黄素可以选择性地抑制Raji细胞增殖;且类似于TSA诱导Raji,HL-60,K562细胞组蛋白乙酰化增加。     

组蛋白去乙酰化酶抑制剂抗血管新生机制的体内研究

目的 探讨组蛋白去乙酰化酶(HDAC)抑制剂对白血病细胞移植瘤血管新生的影响及其机制.方法 12只裸鼠均分为对照组和丙戊酸钠(VPA)用药组.建立Kasumi-1细胞裸鼠移植瘤模型,应用HDAC抑制剂VPA体内用药.RT-PCR和免疫组化检测血管内皮生长因子(VEGF)及其受体(VEGFR) mRNA或蛋白的表达;染色质免疫共沉淀法检测VEGF基因启动子区域染色质内组蛋白H3乙酰化程度的变化.结果 与对照组比较,VPA用药组VEGF及VEGFR2 mRNA和蛋白表达水平明显减少,启动子区域染色质内组蛋白H3的乙酰化程度明显升高.结论 VPA作为HDAC抑制剂,通过提高组蛋白的乙酰化程度,进而抑制血管新生相关因子及受体的表达,阻碍白血病的血管新生.     

组蛋白修饰变化参与曲古抑菌素A缓解的烟草烟雾暴露所致小鼠子宫损伤过程

目的研究组蛋白修饰变化在曲古抑菌素A(trichostatin A,TSA)缓解烟草烟雾(cigarette smoke,CS)暴露所致的雌性小鼠子宫损伤过程中的作用。方法通过CS暴露30 d方法制备CS暴露小鼠子宫损伤模型,CS暴露的同时给予TSA进行治疗;HE染色观察各组小鼠子宫组织形态学变化;Western blot技术检测各组小鼠子宫组织H3K4me1、H3K4me2、H3K4me3、H3K9me1、H3K9me2、H3K9me3和H3K27me3总的修饰水平变化以及GLP(euchromatic histone lysine methyltransferase 1,H3K9甲基转移酶),G9ɑ(euchromatic histone lysine methyltransferase 2,H3K9甲基转移酶),EZH2(enhancer of zeste homolog 2,H3K27me3甲基转移酶)的表达水平。结果TSA缓解CS暴露所致的雌性小鼠子宫间质细胞和腺体数量减少等结构改变。TSA有效抑制了CS暴露激活的小鼠子宫组织H3K9me1的表达,但却进一步激活CS暴露诱导的总H3K27me3修饰水平。TSA可以抑制CS暴露激活的小鼠子宫组织GLP和G9ɑ的表达,进一步激活CS暴露诱导的EZH2表达水平。结论组蛋白修饰变化参与CS暴露所致的小鼠子宫损伤以及TSA的缓解损伤过程。     

环磷酰胺处理雄小鼠对受精卵和二细胞期胚胎DNA甲基化和组蛋白H3K23乙酰化的影响

目的探讨环磷酰胺处理雄性小鼠对受精卵和早期胚胎DNA甲基化修饰和组蛋白H3第23位赖氨酸(H3K23)乙酰化修饰的影响。方法 20只性成熟的ICR雄小鼠饲喂环磷酰胺6 mg.kg-1 4周。雄鼠与雌鼠交配后收集原核期受精卵和二细胞期胚胎。间接免疫荧光染色技术结合激光共聚焦扫描显微镜技术检测胚胎细胞中DNA甲基化和组蛋白H3K23乙酰化修饰的分布和水平。结果与正常对照组相比,环磷酰胺组原核期受精卵和二细胞期胚胎的DNA甲基化修饰水平和分布没有明显差异;但与正常对照组(3%)相比,环磷酰胺组的二细胞期胚胎微核现象(20%)明显升高(P<0.01);与正常对照组相比,环磷酰胺组受精卵雄原核和二细胞期胚胎细胞核的组蛋白H3K23乙酰化水平明显降低(P<0.05),且胚胎间的变化差异明显升高,其中部分原核期受精卵(58%)和二细胞期胚胎(44%)染色水平明显偏低。结论长期低剂量环磷酰胺处理雄鼠可以导致部分受精卵和二细胞期胚胎组蛋白H3K23乙酰化异常,并且显著增加微核发生率。     

喹唑啉酮类选择性PI3Kδ抑制剂的研究进展

磷脂酰肌醇3-激酶δ(PI3Kδ)主要分布在造血细胞和免疫细胞中,对于B细胞的活化、增殖非常重要。PI3Kδ抑制剂可用于免疫相关的疾病与血液肿瘤的治疗。PI3Kδ抑制剂的化学结构多种多样,其中喹唑啉酮类选择性PI3Kδ抑制剂能诱导PI3Kδ构象的改变,是螺旋桨型PI3Kδ抑制剂的代表。本文基于喹唑啉酮类选择性PI3Kδ抑制剂与铰链区结合的结构不同(分为嘌呤类、吡唑并嘧啶类、嘧啶类),对近年来喹唑啉酮类选择性PI3Kδ抑制剂的最新研究进展进行综述。     

Identification of Novel Selective Lysine‐Specific Demethylase 1 (LSD1) Inhibitors Using a Pharmacophore‐Based Virtual Screening Combined with Docking

Lysine‐specific demethylase 1 (LSD1) plays an important role in regulating the lysine methylation at residues K4 and K9 on histone H3. High levels of LSD1 expression have been observed in several malignant tumors. In this study, we presented a pharmacophore‐based virtual screening of a moderate database of 171 143 small molecules. A pharmacophore of LSD1 inhibitors was constructed for the first time and then used to screen the compound library combined with validated molecular docking tools followed by biochemical assays, led to the identification of 9 novel LSD1 inhibitors, showing their IC₅₀ values in a range of 2.41–101 μm . Furthermore, compound XZ 09 exhibited less inhibition against the homologous monoamine oxidase A (MAO‐A) and B (MAO‐B) displaying its moderate selectivity. Our study provides an effective virtual screening method to identify new LSD1 inhibitors and XZ09 represents a potent and selective lead compound to deserve further optimization for the treatment of LSD1 overexpressing cancers.     

Novel compounds protect auditory hair cells against gentamycin-induced apoptosis by maintaining the expression level of H3K4me2

Aminoglycoside-induced hair cell (HC) loss is a major cause of hearing impairment, and the effective prevention of HC loss remains an unmet medical need. Epigenetic mechanisms have been reported to be involved in protecting cochlear cells against ototoxic drug injury, and in this study we developed new bioactive compounds that have similar chemical structures as the epigenetics-related lysine-specific demethylase 1 (LSD1) inhibitors. LSD1 inhibitors have been reported to protect cochlear cells by preventing demethylation of dimethylated histone H3K4 (H3K4me2). To determine whether these new compounds exert similar protective effects on HCs, we treated mouse cochlear explant cultures with the new compounds together with gentamycin. There was a severe loss of HCs in the organ of Corti after gentamycin exposure, while co-treatment with the new compounds significantly protected against gentamycin-induced HC loss. H3K4me2 levels in the nuclei of HCs decreased after exposure to gentamycin, but H3K4me2 levels were maintained in the presence of the new compounds. Apoptosis is also involved in the injury process, and the new compounds protected the inner ear HCs against apoptosis by reducing caspase-3 activation. Together, our findings demonstrate that our new compounds prevent gentamycin-induced HC loss by preventing the demethylation of H3K4me2 and by inhibiting apoptosis, and these results might provide the theoretical basis for novel drug development for hearing protection.     

Desipramine and the phencyclidine derivative BTCP differently inhibit [3H]TCP binding to high- and low-affinity sites.

The effects of N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine (BTCP) and desipramine on [3H]N-[1-(2-thienyl)cyclohexyl]piperidine ([3H]TCP) binding were investigated in vivo and in vitro. In the cerebrum, both drugs were competitive inhibitors of high-affinity [3H]TCP binding. Conversely, in the cerebellum, they were non-competitive inhibitors of low-affinity [3H]TCP binding. These results imply that the different [3H]TCP binding sites have distinct pharmacological properties, and show that, although chemically related to TCP, BTCP has an effect similar to that of desipramine.     

Structure–Activity Relationship and In Silico Evaluation of cis- and trans-PCPA-Derived Inhibitors of LSD1 and LSD2

trans-2-Phenylcycloproylamine (trans-PCPA) has been used as the scaffold to develop covalent-binding inhibitors against lysine-specific demethylase 1 (LSD1/KDM1A), a therapeutic target for several cancers. However, the effects of different structural moieties on the inhibitory activity, selectivity, and reactivity of these derivatives, including the cis isomers, against LSD1 and its paralogue LSD2/KDM1B are not fully understood. Here we synthesized 65 cis- and trans-PCPA derivatives and evaluated their inhibitory activity against LSD1 and LSD2. One of the derivatives, 7c (cis-4-Br-2,5-F₂-PCPA; S1024), inhibited LSD1 and LSD2 with K_i values of 0.094 μM and 8.4 μM, respectively, and increased the level of dimethylated histone H3 at K4 in CCRF-CEM cells. A machine learning-based regression model (Q² = 0.61) to predict LSD1-inhibitory activity was also constructed and showed a good prediction accuracy (R² = 0.81) for 12 test-set compounds, including 7c. The present methodology would be useful when designing covalent-binding inhibitors for other enzymes.     

Triptolide induces cell-cycle arrest and apoptosis of human multiple myeloma cells in vitro via altering expression of histone demethylase LSD1 and JMJD2B

Aim:

To elucidate the relationship between triptolide-induced changes in histone methylation and its antitumor effect on human multiple myeloma (MM) cells in vitro.

Methods:

Human multiple myeloma cell line RPMI8226 was used. Apoptosis was evaluated using Annexin-V-FITC/PI-labeled flow cytometry, Hoechst 33258 staining, and transmission electron microscopy. Flow cytometry was used to detect the cell cycle distribution of the apoptotic cells. The presence of the LSD1, JMJD2B, H3K4me2, H3K9me2, and H3K36me2 proteins was verified by Western blot analysis. Semi-quantitative real-time PCR was performed to examine the expression of LSD1 and JMJD2B.

Results:

Triptolide (10–160 nmol/L) suppressed the proliferation of MM cells in a dose- and time-dependent manner with an IC₅₀ value of 99.2±9.0 nmol/L at 24 h. Triptolide (50 nmol/L) induced G₀/G₁ cell cycle arrest in MM cells. The agent (50–150 nmol/L) induced apoptosis of MM cells in a dose-dependent manner. The same concentrations of triptolide suppressed the expression of dimethylated H3K4, dimethylated H3K9 and dimethylated H3K36 by altering the expression of histone demethylase LSD1 and JMJD2B without affecting the expression of histone demethylase LSD1.

Conclusion:

Triptolide potently inhibits the growth of MM cells via regulating the expression of histone demethylase LSD1 and JMJD2B, which lead to abnormal histone methylation.     

Inhibitors of LSD1 as a potential therapy for acute myeloid leukemia

Introduction: Epigenetic dysregulation plays a critical role in the pathogenesis of acute myeloid leukemia (AML). Alterations in histone methylation lead to aberrant silencing of expression of multiple genes involved in tumor suppression and cell cycling, resulting in myeloid maturation arrest and proliferation of early myeloid progenitors. One promising approach targeting chromatin regulatory proteins is inhibition of lysine specific demethylase-1 (LSD1), an enzyme responsible for demethylation of histone H3 as well as other functions

Areas covered: Available literature on LSD1 in normal and malignant hematopoiesis was identified in PubMed and reviewed. Areas addressed here include the biology of LSD1, pharmacologic inhibitors, and preclinical data supporting the rationale for LSD1 inhibition in AML therapy.

Expert opinion: LSD1 inhibitors represent a promising novel epigenetic approach for AML therapy. Preclinical studies have revealed that pharmacologic LD1 inhibitors function primarily by altering stem cell programs and restoring myeloid differentiation to AML cells. These effects are markedly enhanced in combination with trans-retinoic acid or histone deacetylase inhibitors with little toxicity. Currently, multiple oral LSD1 inhibitors are undergoing phase 1 investigation in patients with AML. The results of these clinical trials are eagerly awaited.     

The rat brain phencyclidine (PCP) receptor. A putative K+ channel

Receptor binding studies were carried out to test whether the rat brain phencyclidine (PCP) receptor is part of a K+ channel. [3H]PCP, and two analogs, [3H]TCP and m-amino[3H]PCP, labeled a single receptor on rat brain synaptic membranes. Each compound bound to a similar number of sites (Bmax = 2.7 pmol bound/mg protein); the apparent dissociation constants for these compounds (KD less than 0.3 microM) decreased with increasing temperature. The following observations indicate that the PCP receptor is part of a K+ channel: (1) aminopyridines (AP) and tetraalkylammonium ions blocked [3H]PCP binding; their respective orders of potency, 4-AP = 3,4-diAP much greater than 3-AP, and tetrabutylammonium (TBA) greater than tetraethylammonium much greater than tetramethylammonium, paralleled their abilities to block K+ channels, (2) the order of potency of PCP and its analogs for binding to the PCP receptor, TCP greater than PCE greater than m-amino-PCP greater than PCP greater than PCPY greater than m-nitro-PCP, paralleled their rank order for blocking brain K+ channels, and (3) the stereospecific displacement of [3H]PCP binding by the isomers of the "sigma" ligands, (+)N-allyl-normetazocine (NANM) greater than (-)NANM, and (-)cyclazocine greater than (+)cyclazocine, and of the dioxolanes, dexoxadrol much greater than levoxadrol, paralleled their abilities to block brain K+ channels. Reciprocal plot and Schild plot analyses indicated that TBA, (+)NANM and dexoxadrol were competitive inhibitors at the PCP receptor, whereas 4-AP had an allosteric interaction.