肾癌组织中Tim-3基因的甲基化分析

目的分析肾癌组织中Tim-3基因启动子的甲基化情况,探讨Tim-3甲基化在肾癌发生中的可能作用。方法采用甲基化特异性PCR（MSP）检测20例肾癌组织和3例癌旁组织中Tim-3基因启动子甲基化状态,分析检测结果。结果肾癌组织中有11例（55%）检测到了Tim-3基因甲基化表达,相应癌旁组织中没有检测到Tim-3基因甲基化表达。结论肾癌组织中Tim-3基因启动子发生甲基化,Tim-3基因甲基化可能与肾癌的发生发展有关。     

定量检测血浆RASSF1A甲基化在晚期肺癌患者个体化治疗中的应用

摘要:目的：定量检测晚期肺癌患者化疗过程中血浆RAS相关区域家族1A基因(RASSF1A)甲基化水平,探讨其在个体化治疗中的应用价值。 方法：采集24例晚期肺癌患者化疗前后静脉血共135份,用荧光定量甲基化特异性PCR (MSP)检测RASSF1A基因的甲基化水平,观察化疗前后的变化情况。 结果：13例部分缓解组(partial remission,PR)患者化疗后甲基化定量水平明显升高(P＜0.05),而11例未缓解组(stable disease,SD或progressive disease,PD)的患者化疗前后甲基化水平无明显变化;生存时间≥12个月的13例患者化疗后甲基化定量水平也明显升高(P＜0.01),而生存时间<12个月的11例患者化疗前后甲基化水平无明显变化。生存曲线分析显示,化疗后有甲基化水平升高改变的患者总体生存时间更长(P＜0.01）。 结论：晚期肺癌患者化疗前后血浆RASSF1A甲基化定量水平的检测,对评估化疗的疗效及预后有一定的价值,对个体化化疗的药物选择有一定的指导意义。     

人胚胎骨髓MSC及其突变株F6细胞DAPK基因表达及启动子甲基化检测

摘要：目的：研究人胚胎骨髓间充质干细胞（fetal mesenchymal stem cells, FMSC）及其突变肿瘤细胞F6死亡相关蛋白激酶（deathassociated protein kinase,DAPK）基因的表达及启动子区域甲基化。 方法：用RT-PCR和甲基化特异性PCR（methylationspecific PCR, MS-PCR）技术对FMSC及F6细胞系DAPK 基因的表达和启动子甲基化状态进行检测,并对甲基化产物测序鉴定。 结果：DAPK基因在FMSC中表达而在F6中不表达。通过MS-PCR检测证实F6中DAPK基因发生甲基化,FMSC中DAPK基因发生未完全甲基化。 结论：DAPK基因启动子区域发生甲基化可能是促使其基因表达下调的重要机制,在FMSC突变成F6肿瘤细胞过程中发挥重要作用。     

Hypomethylation of the serotonin receptor type‐2A Gene (HTR2A) at T102C polymorphic site in DNA derived from the saliva of patients with schizophrenia and bipolar disorder

Several lines of evidence indicate that dysfunction of serotonin signaling and HTR2A receptor are involved in the pathogenesis of schizophrenia (SCZ) and bipolar disorder (BD). DNA methylation of HTR2A at T102C polymorphic site influences HTR2A expression and aberrant DNA methylation of HTR2A promoter was reported in postmortem brain of patients with SCZ and BD. Hypothesizing that the brain's epigenetic alteration of HTR2A may also exist in peripheral tissues that can be used as a diagnostic/therapeutic biomarker, we analyzed HTR2A promoter DNA methylation in DNA extracted from the saliva of patients with SCZ and BD, and their first degree relatives versus normal controls. Bisulfite sequencing was used to screen DNA methylation status of the HTR2A promoter CpGs and qMSP was used to quantify the degree of cytosine methylation at differentially methylated sites. Most of the cytosines of the HTR2A promoter were unmethylated. However, CpGs of the ?1438A/G polymorphism site, ?1420 and ?1223 were >95% methylated. The CpG at T102C polymorphic site and neighboring CpGs were ～70% methylated both in the patients and controls. qMSP analysis revealed that the cytosine of the T102C polymorphic site was significantly hypo‐methylated in SCZ, BD, and their first degree relatives compared to the controls. Cytosine methylation of HTR2A at T102C polymorphic site in DNA derived from the saliva can potentially be used as a diagnostic, prognostic, and/or therapeutic biomarker in SCZ and BD. However, these preliminary observations need to be replicated in other populations with a larger sample size to be considered for clinical applications. © 2011 Wiley‐Liss, Inc.     

The epigenetics of autoimmunity

The etiology of autoimmune diseases remains largely unknown. Concordance rates in monozygotic twins are lower than 50% while genome-wide association studies propose numerous significant associations representing only a minority of patients. These lines of evidence strongly support other complementary mechanisms involved in the regulation of genes expression ultimately causing overt autoimmunity. Alterations in the post-translational modification of histones and DNA methylation are the two major epigenetic mechanisms that may potentially cause a breakdown of immune tolerance and the perpetuation of autoimmune diseases. In recent years, several studies both in clinical settings and experimental models proposed that the epigenome may hold the key to a better understanding of autoimmunity initiation and perpetuation. More specifically, data support the impact of epigenetic changes in systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis and other autoimmune diseases, in some cases based on mechanistical observations. We herein discuss what we currently know and what we expect will come in the next future. Ultimately, epigenetic treatments already being used in oncology may soon prove beneficial also in autoimmune diseases.     

Identification of disease-associated DNA methylation in intestinal tissues from patients with inflammatory bowel disease

Lin Z, Hegarty JP, Cappel JA, Yu W, Chen X, Faber P, Wang Y, Kelly AA, Poritz LS, Peterson BZ, Schreiber S, Fan J‐B, Koltun WA. Identification of disease‐associated DNA methylation in intestinal tissues from patients with inflammatory bowel disease. Overwhelming evidence supports the theory that inflammatory bowel disease (IBD) is caused by a complex interplay between genetic predispositions of multiple genes, combined with an abnormal interaction with environmental factors. It is becoming apparent that epigenetic factors can have a significant contribution in the pathogenesis of disease. Changes in the methylation state of IBD‐associated genes could significantly alter levels of gene expression, potentially contributing to disease onset and progression. We have explored the role of DNA methylation in IBD pathogenesis. DNA methylation profiles (1505 CpG sites of 807 genes) of matched diseased (n = 26) and non‐diseased (n = 26) intestinal tissues from 26 patients with IBD [Crohn's disease (CD) n = 9, ulcerative colitis (UC) n = 17] were profiled using the GoldenGate? methylation assay. After an initial identification of a panel of 50 differentially methylated CpG sites from a training set (14 non‐diseased and 14 diseased tissues) and subsequent validation with a testing set (12 non‐diseased and 12 diseased tissues), we identified seven CpG sites that are differentially methylated in intestinal tissues of IBD patients. We have also identified changes in DNA methylation associated with the two major IBD subtypes, CD and UC. This study reports IBD‐associated changes in DNA methylation in intestinal tissue, which may be disease subtype‐specific.     

DNA methylation studies on imprinted loci in a male monozygotic twin pair discordant for Beckwith–Wiedemann syndrome

Tierling S, Souren NY, Reither S, Zang KD, Meng‐Hentschel J, Leitner D, Oehl‐Jaschkowitz B, Walter J. DNA methylation studies on imprinted loci in a male monozygotic twin pair discordant for Beckwith–Wiedemann syndrome. Beckwith–Wiedemann syndrome (BWS) is one of the most prevalent congenital disorders predominantly caused by epigenetic alterations. Here we present an extensive case study of a monozygotic monochorionic male twin pair discordant for BWS. Our analysis allows to correlate BWS symptoms, like a protruding tongue, indented ears and transient neonatal hypoglycaemia, to an abnormal methylation at the KvDMR1. DNAs extracted from peripheral blood, skin fibroblasts, saliva and buccal swab of both twins, their sister and parents were analysed at 11 differentially methylated regions (DMRs) including all four relevant DMRs of the BWS region. The KvDMR1 was exclusively found to be hypomethylated in all cell types of the affected BWS twin, while the unaffected twin and the relatives showed normal methylation in fibroblasts, buccal swab and saliva DNA. Interestingly, the twins share a common blood‐specific hypomethylation phenotype most probably caused by a feto‐fetal transfusion between both twins. Because microsatellite analysis furthermore revealed a normal biparental karyotype for chromosome 11, our results point to an exclusive correlation of the observed BWS symptoms to locally restricted epimutations at the KvDMR1 of the maternal chromosome.     

FOXP3调控中的表观遗传学现象

FOXP3转录因子是维持调节性T细胞(Treg)免疫抑制功能的必要条件。研究发现FOXP3也可在抗原受体激活的非调节性T细胞表达,使其作为Treg的特异性标志受到质疑。实验证明Treg细胞的FOXP3基因座含有多个去甲基化区域,且似乎更有特异性。FOXP3基因表达和蛋白功能发挥随着组蛋白甲基化和乙酰化水平而改变。DNA甲基化转移酶抑制剂(DNMTi)或组蛋白去乙酰化酶抑制剂(HDACi)可诱导具有免疫抑制功能的Treg产生。本文对FOXP3基因表达调控,蛋白修饰后调节其它基因表达过程中的表观遗传学现象及临床应用前景作一综述。     

母胎间差异甲基化片段在无创性产前诊断中的应用价值

目的探讨HLCS、RASSF1A片段在母胎间甲基化状态的差异并评估其在无创性产前诊断中的应用价值。方法收集388例孕妇血浆,其中126例同时收集外周血细胞及胎盘（或绒毛）组织,采用甲基化敏感性限制性酶切联合荧光定量PCR（MSRE＋PCR）技术,检测母胎间HLCS基因、RASSF1A基因甲基化状态的差异,分析其影响因素,并根据孕妇血浆中胎源性HLCS/RASSF1A浓度比值判断胎儿21号染色体数目。结果研究证实HLCS及RASSF1A在胎盘或绒毛组织中均呈高甲基化状态,而在母体外周血细胞呈现低甲基化状态,且这种甲基化差异不受孕妇年龄、孕周、胎儿性别的影响。采用MSRE＋PCR技术对孕妇血浆中HLCS、RASSF1A片段的检出率分别为97.4%和96.9%。计算274例正常妊娠孕妇血浆中胎源性HLCS/RASSF1A比值,确定其95%的参考值范围为0.34～2.02,以此为标准判断102例胎儿21号染色体数目,其中98例二倍体妊娠的准确率为95.9%（94/98）,4例21三体综合征妊娠均获正确诊断。结论高甲基化HLCS、RASSF1A基因可作为孕妇血浆中胎源DNA的标志物,且有望根据孕妇血浆中甲基化HLCS/RASSF1A浓度比值进行21三体综合征的无创性产前诊断。     

Helicobacter pylori induces promoter hypermethylation and downregulates gene expression of IRX1 transcription factor on human gastric mucosa

Background and Aim: Gene silence of IRX1 tumor suppressor by promoter CpG methylation combined with loss of heterozygosity (LOH) has been identified in human gastric cancer. This study investigated the association between methylation of IRX1 and Helicobacter pylori infection in gastric mucosa tissues and cell line. Methods: IRX1 methylation was studied by methylation specific polymerase chain reaction (MSP) and bisulfate sequencing polymerase chain reaction (BSP) methods in gastric mucosa tissues from H. pylori‐positive chronic gastritis patients or H. pylori‐negative chronic gastritis patients. Promoter activity, methylation status and gene expressing level of IRX1 were evaluated by persistent infecting H. pylori on human gastric cells GES‐1 in vitro. Electron microscopy was used to observe the effect of H. pylori infection on GES‐1 gastric mucosa cells. Results: The methylation level of IRX1 promoter in H. pylori positive chronic gastritis and H. pylori negative chronic gastritis was 55.30% ± 13.17 versus 5.20% ± 6.31, respectively (P < 0.01). H. pylori infection stimulated increased microvillus, and mucous secretion on GES‐1 cells. Infection of H. pylori induced IRX1 promoter methylation and downregulation of the promoter activity as well as gene expression significantly. Conclusions: This study firstly demonstrated that H. pylori infection contributes to IRX1 promoter methylation on gastric mucosa.