EZH2在消化系统肿瘤发生发展中的作用

消化系统肿瘤是一类由多因素和多基因异常引发的恶性肿瘤,相关基因的异常表观遗传调控与其发生和发展密切相关。果蝇zeste基因增强子人类同源物(enhancer of zeste homolog 2,EZH2)是多梳蛋白抑制复合体2(polycomb repressive complex2,PRC 2)的核心亚基,也是一种重要的负性表观遗传调控蛋白质,它通过催化组蛋白H3K 27位点的甲基化而使肿瘤抑制基因表达沉默。近年来研究发现,EZH2在消化系统肿瘤组织和细胞中高表达,并与肿瘤的增殖、侵袭和转移显著性正相关,可独立用作肿瘤患者不良预后指标。对EZH2与消化系统肿瘤相互关系的深入研究,将对这类肿瘤的治疗提供新的分子靶点和新的途径。     

EZH2在卵巢癌中的研究进展

果蝇zeste基因增强子人类同源2(enhancer of zeste homolog 2,EZH2)是近年来肿瘤领域研究的热门靶点基因,其在卵巢恶性肿瘤中表达增高,与卵巢癌的发生发展及预后密切相关。EZH2作为一种重要的负性表观遗传调控蛋白,可通过催化组蛋白3赖氨酸27三甲基化(H3K27me3)和调控新型钙黏蛋白分子CD13等影响卵巢细胞的增殖、迁移和侵袭,对EZH2的深入研究将为治疗卵巢恶性肿瘤提供新的分子靶点。本文就该领域的最新研究进展作一简要综述。     

EZH2抑制剂与肿瘤治疗

果蝇Zeste基因增强子人类同源物2(Drosophila zeste gene enhancer of human homolog 2,EZH2)是一种参与基因负性表观遗传调控的甲基转移酶。研究发现,EZH2在多种肿瘤组织中高表达,并与肿瘤的发生发展和侵袭转移密切相关,由此成为抗肿瘤治疗新的分子靶点。目前已研发出多种EZH2抑制剂用于肿瘤的基础和临床治疗研究,并取得令人鼓舞的结果。本文将对EZH2小分子抑制剂的研究进展做简要综述。     

EZH2在心脏与血管发育中的作用

Zeste基因增强子人类同源物2(enhancer of zeste homolog 2, EZH2)是多梳蛋白抑制复合物2(polycomb repressive complex 2, PRC2)的主要元件之一，利用组蛋白甲基化酶活性发挥经典作用，抑制靶基因的表达。此外，EZH2通过甲基化其他蛋白，作为蛋白支架分子募集转录相关分子介导转录激活，与lncRNA及miRNA相互作用等非经典途径调控各项生命活动，与干细胞分化和组织器官发育关系密切。EZH2及其功能相关分子在心脏发育、血管发生等过程中发挥着至关重要的作用。靶向敲除小鼠心脏Ezh2基因会影响心肌组织及内皮源性组织的正常发育，造成广泛性的心脏发育缺陷。EZH2参与调控正常组织和肿瘤组织的血管生成，维持新生血管完整性，并参与调控内皮间质化和内皮造血转化。本文探讨了EZH2在心脏和血管发生领域的影响效应、调控机制，及其与相关疾病的关系。     

CXXC4、EZH2在口腔鳞状细胞癌中表达及临床意义

目的:探讨口腔鳞状细胞癌(Oral Squamous Cell Carcinoma,OSCC)中CXXC指蛋白4(CXXC finger protein 4,CXXC4)与Zeste基因增强子同源物2(Enhancer of zeste homolog 2,EZH2)的表达、相关性及与临床病理特征之间的关系,为OSCC的早期诊断、治疗、判断预后及预防等提供参考依据。方法:采用免疫组织化学S-P法检测CXXC4蛋白及EZH2蛋白在60例口腔鳞状细胞癌组织及20例非肿瘤患者正常口腔黏膜组织中的表达情况,分析二者与口腔鳞状细胞癌临床病理特征的相关性。结果:口腔鳞状细胞癌组织中CXXC4蛋白的表达率为35.0%(21/60),明显低于正常口腔黏膜组织的60.0%(12/20)(P0.05);口腔鳞状细胞癌中EZH2蛋白的表达率为70.0%(42/60),高于正常口腔黏膜组织的25%(5/20)(P0.05)。CXXC4蛋白与EZH2蛋白的表达与口腔鳞状细胞癌的病理分化程度、TNM分期及淋巴结转移等密切相关(P0.05),而与年龄、性别及肿瘤直径大小等无关。CXXC4蛋白与EZH2蛋白在OSCC中表达呈负相关(r=-0.511,P0.001)。结论:CXXC4蛋白的表达下调或缺失以及EZH2蛋白的表达上调或过表达与口腔鳞状细胞癌的发生、发展及侵袭转移有关,可能作为口腔鳞状细胞癌预后预测的参考指标。     

EZH2在胃癌组织中的表达及与Hp-L型感染关系的探讨

目的探讨EZH2在胃癌组织中表达的意义及与幽门螺杆菌L型(Helicobacter pylori-L,Hp-L)感染的关系。方法 (1)应用免疫组织化学Elivision法和革兰染色法检测80例胃癌组织及30例癌旁组织(对照组)中EZH2蛋白的表达和Hp-L型的感染情况;(2)采用逆转录多聚酶链反应(RT-PCR)技术检测30例新鲜胃癌组织及对应切缘正常胃黏膜组织(对照组)中EZH2的mRNA表达。结果胃癌组EZH2蛋白表达的阳性率高于对照组(P<0.05),且EZH2表达水平升高与肿瘤大小、浸润深度、淋巴结转移和TNM分期有关(P<0.05),与性别、年龄无关(P>0.05);RT-PCR显示,肿瘤组织、远端正常对照组织的EZH2表达量差异明显(P<0.01)。胃癌组Hp-L型检出率78.8%(63/80)与对照组23.3%(7/30)有显著性差异(P<0.05),与免疫组化Hp-L型抗原表达率73.8%(59/80)无显著性差异(P>0.05),Hp-L检出阳性率为71.3%(57/80);癌组中Hp-L型感染阳性组的EZH2表达阳性率高于Hp-L型阴性组(P<0.05),且Hp-L型阳性率和EZH2蛋白的表达呈正相关(r=0.250,P<0.05)。结论 EZH2蛋白和mRNA在胃癌中的表达增加,且与胃癌的浸润、转移相关,其机制可能与幽门螺杆菌L型(Hp-L型)感染有关。     

组蛋白甲基酶EZH2的研究进展

EZH2(enhancer of zeste homolog 2)作为重要的表观遗传修饰物,是PcG(Polycomb group)蛋白家族的重要成员之一,在调控基因表达的过程中起关键作用。EZH2主要对组蛋白H3K27进行甲基化,从而沉默下游基因。它在细胞增殖、分化及肿瘤形成方面都有重要作用。特别是近年来的研究表明,EZH2与很多恶性肿瘤的转移和侵略有关。随着对其研究的深入,EZH2将有望在新药作用靶点及疾病治疗方面发挥作用。     

HGF和EZH2在宫颈癌组织中的表达及其与临床病理特征的关系

目的:探讨肝细胞生长因子(HGF)、果蝇zeste基因增强子2(EZH2)在宫颈癌组织中的表达及其与临床病理特征的关系。方法:选取2016年10月到2018年1月期间在新疆医科大学附属肿瘤医院接受治疗的宫颈癌患者50例,收集其手术切除的病理组织作为宫颈癌组的检测标本,另选取同期在我院收治的子宫肌瘤患者,收集其行全子宫切除术时切除的宫颈组织,其中上皮内瘤样病变(CIN)组织和正常宫颈组织各50例,CIN组织作为CIN组的检测标本,正常宫颈组织作为对照组的检测标本。比较宫颈癌组、CIN组和对照组标本中HGF和EZH2的阳性表达情况。分析HGF和EZH2的表达与宫颈癌患者临床病理特征的关系,分析宫颈癌组织中HGF、EZH2表达的相关性。结果:各组标本中的HGF和EZH2的阳性表达率整体比较差异均有统计学意义(P0.05),宫颈癌组、CIN组的HGF和EZH2的阳性表达率均明显高于对照组,且宫颈癌组EZH2的阳性表达率高于CIN组(P0.05)。宫颈癌组织中HGF和EZH2的表达与年龄、肿瘤类型、肿瘤大小无关(P0.05),临床分期II期、有淋巴结转移、病理分级G3的宫颈癌组织中HGF和EZH2的阳性表达率高于临床分期I期、无淋巴结转移、病理分级G1+G2的宫颈癌组织(P0.05)。经Spearman相关分析显示,宫颈癌组织中HGF与EZH2表达呈正相关(P0.05)。结论:HGF和EZH2在宫颈癌组织中呈高表达,且其表达水平与临床分期、淋巴结转移、病理分级有关。     

EZH2蛋白在食管上皮永生化细胞系和恶性转化细胞系中的表达

目的研究EZH2蛋白在食管上皮永生化细胞系(SHEE)和恶性转化细胞系(SHEEC)中的表达。方法采用免疫细胞化学染色、免疫印迹分析和流式细胞术检测两种细胞系EZH2蛋白的表达。结果两种细胞EZH2蛋白染色均呈阳性,阳性反应定位于细胞核,部分细胞胞浆也有阳性着色。免疫印迹分析表明SHEEC细胞和SHEE细胞的总蛋白、核蛋白在分子质量约90ku的位置均出现特异性印迹条带。SHEE细胞中EZH2蛋白的表达强于SHEEC细胞(P<0.05)。流式细胞术显示EZH2蛋白在两种细胞中均有表达,两者的平均荧光强度无明显差别;阳性细胞率均较高,其中SHEE细胞阳性率高于SHEEC细胞。结论EZH2蛋白在SHEE细胞和SHEEC细胞中高表达可能参与了它们的恶性改变;而EZH2蛋白在两种细胞系中的差异表达可能与细胞的分化程度及来源于胚胎食管上皮细胞相关。     

EZH2:调节癌症发展的多重表观遗传因子

果蝇zeste基因增强子的人类同源物2(enhancer of zeste homolog 2,EZH2)是表观遗传调控因子多梳抑制复合体2(polycomb repressive complex 2,PRC2)的催化亚基,可催化组蛋白H3第27位的赖氨酸三甲基化并沉默靶基因转录,调控癌症进展及干细胞干性维持等多种生命活动。多项研究证明,EZH2不仅具有经典的PRC2依赖的转录抑制作用,还可通过非PRC2依赖的方式激活靶基因转录,亦或通过其激活性或失活性的突变调节下游靶基因的活性。目前,已在多种癌细胞中检测到了EZH2的过表达或突变,并且其变化与癌症的恶性程度密切相关。因此,靶向EZH2及其介导的信号通路的研究将成为一个全新的癌症基因治疗的方向。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.