用尿沉淀细胞DNA甲基化状态的分析检测膀胱癌

目的：确定尿沉淀细胞DNA中的13个肿瘤相关基因启动子的甲基化谱式分析在膀胱癌诊断中的价值。方法：用定性甲基化特异性（methylation specific polymerase chain reaction，MSP）的方法，对92例临床确诊的膀胱癌患者、23例非肿瘤性尿路疾病患者、6例脑外科患者、7例健康志愿者检测了尿沉淀细胞DNA中肿瘤相关基因启动子的甲基化状态。结果：在临床确诊的92例膀胱癌患者中被检测的13个基因的高甲基化状态出现频率显著高于23例非肿瘤性尿路疾病患者，差异有统计学意义（P〈0．05）。而6例脑外科患者和7例正常健康人的尿沉淀细胞DNA中，上述基因均为去甲基化状态。若以任一个基因高甲基化为膀胱癌的指征，88．0％（81／92例）的膀胱癌可被检出。结论：MSP法分析尿沉淀细胞DNA中肿瘤相关基因启动子的甲基化状态可有效地检出膀胱癌。     

尿沉淀细胞DNA的甲基化谱式分析和膀胱癌的诊断

目的：寻找并评估通过对尿沉淀细胞DNA甲基化分析检出膀胱癌的基因组合。方法：甲基化特异性PCR（methylation specific polymerase chain reaction,MSP）。结果：对3株膀胱癌细胞系进行的20个基因启动子区域CpG岛甲基化状态分析发现,除BRCA1以外其他基因至少在细胞株的1个等位基因呈高甲基化状态。对40例膀胱癌组和3组非膀胱癌对照组的尿沉淀细胞DNA进行了6个基因甲基化状态分析发现,SALL3在膀胱癌组甲基化率为67.5%（27/40）,MT1A为50.0%（20/40）,HPP1为50.0%（20/40）,MYOD1为37.5%（15/40）,BRCA1为32.5%（13/40）,TMS1为5.0%（2/40）。这6个基因在3个非膀胱癌对照组,即非肿瘤性泌尿生殖系统疾病患者23例、脑外科患者6例和正常人群7例均呈去甲基化状态,所以可以受试基因中任一个基因呈现高甲基化状态作为膀胱癌的指征,该法检出膀胱癌的敏感性为90.0%（36/40）。结论：对这5个基因在尿沉淀细胞DNA中甲基化状态的检测可望有效地检出膀胱癌。     

宫颈癌组织中DAPK基因启动子甲基化的研究

背景与目的:已有研究表明DNA异常甲基化在肿瘤的发生、发展中发挥了重要作用.本研究旨在探讨宫颈癌组织中DAPK(death-associated protein kinase)启动子甲基化与基因失活的关系.方法:应用甲基化特异性PCR (methylation-specific PCR,MSP)技术检测52例宫颈癌、60例宫颈上皮内瘤样病变(cervical intraepithelial neoplasia,CIN)和20例正常宫颈鳞状上皮DAPK启动子甲基化状况,应用免疫组化方法检测其蛋白表达;分析DAPK启动子甲基化和基因失活与宫颈癌临床病理因素之间的关系.结果:正常宫颈组织不存在DAPK基因启动子CpG岛甲基化,而CIN和宫颈癌中的DAPK甲基化率分别为18.3%(11/60)、65.4%(34/52),三者之间的差异有统计学意义(P<0.05).宫颈鳞癌的DAPK甲基化率明显高于腺癌(分别为80.0%和16.7%),其差异有统计学意义(P<0.001).DAPK启动子甲基化和DAPK蛋白表达之间呈负相关(r=-0.849,P<0.001).结论:DAPK启动子CpG岛甲基化可导致基因失活,并可能参与宫颈癌的发生.     

胃癌细胞系和胃癌组织中EphA7基因的高甲基化及其临床意义

背景与目的：启动子区CpG岛高甲基化是导致基因转录水平下调的重要表观遗传学机制,我们前期的研究发现EphA7基因在部分胃癌中表达下调.本研究探讨EphA7基因下调的机制及其临床意义.方法：检测6株胃癌细胞及62例胃癌标本中EphA7基因甲基化状态.采用同位素掺入方法对胃癌细胞系的EphA7基因表达进行半定量RT-PCR测定;利用亚硫酸氢钠处理DNA后,进行DNA测序和甲基化特异性PCR检测.结果：对胃癌细胞系亚硫酸氢钠修饰后DNA测序发现,在EphA7基因启动子区内CpG岛存在超甲基化现象,利用甲基化特异性PCR检测胃癌标本证实,在部分胃癌组织中存在高甲基化.高甲基化与胃癌细胞的分化程度有关（P=0.03）.结论：高甲基化是导致该基因下调的机制之一.EphA7基因在胃癌的发生过程中可能发挥一定作用.     

3株肺癌细胞中9个肿瘤相关基因的启动子甲基化状态和部分基因表达的相关性

目的对3株肺癌细胞中9个肿瘤相关基因的启动子甲基化状态和部分基因表达的相关性进行评估.方法通过甲基化特异性多聚酶链反应法(MSP)结合DNA测序来确定3株肺腺癌细胞株(A549,SH77和SPE-A-1)中9个基因的启动子CpG岛的甲基化状态:APC,CDH13,DAPK1,MGMT,MYOD1,p16INK4a,p73,RAR-β和WT1基因.同时采用半定量RT-PCR的方法来量度下列5个基因的表达:CDH13,MGMT,MYOD1,RAR-β和WT1基因.结果在9个受检基因之中,下列4个基因在三株细胞中均呈同样的甲基化谱式:仅有去甲基化:APC和DAPK1,以及兼有甲基化和去甲基化:p73和p16INK4a.而其余5个基因则表现为不同的甲基化模式.尽管,这5个基因的表达谱式大体上符合其启动子CpG岛甲基化的表达静息的原则,个别的例外亦是有的.这提示着与DNA甲基化状态无关的机制可能也会参与该基因的表达调控.结论肺癌细胞株中的肿瘤相关基因的启动子CpG岛的过甲基化可与该基因的表达状态有较高的相关性.     

启动子区5′CpG岛去甲基化对人肠癌RKO细胞生物学表型的影响(英文)

目的:探讨DNA启动子区5′CpG岛甲基化状态与人肠癌RKO细胞生物学特征的关系。方法:应用特异性DNA甲基转移酶抑制剂-5-氮-2′-脱氧胞苷(5-Aza-2’-deoxycytidine,5-Aza-CdR)处理肠癌RKO细胞72小时,甲基化特异性PCR(methylation-specific PCR,MSP)及DNA测序法分析p16/CDKN2抑癌基因5’CpG岛甲基化状态;MTT、FCM、荧光染色及透射电镜检测启动子区去甲基化后对细胞生长、形态和细胞周期凋亡的影响。结果:肠癌RKO细胞p16/CDKN2基因5’CpG岛呈高甲基化状态;DNA甲基转移酶抑制剂(5-Aza-CdR)能较好地逆转启动子区胞嘧啶甲基化状态;CpG岛去甲基化后能明显地抑制肠癌细胞的生长,增加细胞群体倍增时间(P<0.01),诱导肠癌细胞凋亡,并呈良好的量效依赖关系。结论:通过逆转CpG岛高甲基化能有效地抑制肠癌细胞增殖,为临床治疗大肠癌提供新的作用靶点。     

胃癌患者外周血与胃癌组织中ERCC1基因甲基化的关系及其意义

背景与目的：胃癌的发生基于基因和表观遗传学机制,表观遗传学的改变在胃癌的发展中起到重要作用。DNA甲基化是目前研究最多、最为深入的一种表观遗传学表达机制。DNA甲基化是一个可逆性过程。核苷酸切除修复交叉互补基因1(excision repair cross-complementing gene 1,ERCC1)是一种DNA损伤修复基因。本研究检测胃癌患者外周血与胃癌组织中ERCC1基因启动子CpG岛甲基化状态,探讨两者的关系及其意义。方法：采用甲基化特异性PCR技术,检测30例胃癌患者外周血、胃癌组织中ERCC1基因启动子CpG岛甲基化状态。结果：胃癌组织中ERCC1基因启动子CpG岛甲基化率为76.7%(23/30),外周血中ERCC1基因启动子CpG岛甲基化率为63.3%(19/30),差异无统计学意义。结论：胃癌患者外周血中的ERCC1基因启动子CpG岛甲基化率与胃癌组织中相似,检测胃癌患者外周血中的ERCC1基因启动子CpG岛甲基化状态为治疗胃癌提供一个简便、快捷、可靠的途径,同时也为以ERCC1基因启动子CpG岛甲基化作为靶点治疗胃癌提供了可靠的理论依据。     

DNA修复酶基因MGMT启动子区异常甲基化与食管癌的关系

背景与目的： 分析食管癌组织中MGMT启动子区CpG岛甲基化状态和食管癌发病风险的关系,探讨MGMT基因启动子的异常甲基化在食管癌筛查及早期诊断中的意义。 材料与方法： 对江苏淮安的91例新发食管癌病例的癌组织、癌旁组织及外周血血浆样本提取DNA,应用甲基化特异性PCR(MSP)分析MGMT启动子区CpG岛的甲基化状态;对食管癌组织和癌旁组织提取总RNA,采用SYBR GREEN I 实时荧光定量逆转录-聚合酶链反应(RT-PCR)测定MGMT的mRNA水平。 结果： MGMT启动子区CpG岛异常甲基化与食管癌发病风险增高有关联 (OR=7.750, 95％CI=2.736～21.955);MGMT启动子区CpG岛甲基化状态与MGMT mRNA水平无显著相关;血浆循环DNA中MGMT启动子区CpG岛甲基化与癌组织中MGMT启动子区CpG岛甲基化相关(P<0.01),血浆循环DNA中MGMT启动子区CpG岛甲基化检出率与癌组织中MGMT启动子区CpG岛甲基化检出率中度相关(Kappa=0.603, P<0.01)。 结论： MGMT基因的启动子区CpG岛的异常甲基化与食管癌发病风险增加有关;检测血浆循环DNA中MGMT基因启动子的异常甲基化,可为食管癌的筛查、早期诊断提供有价值的信息。     

胃癌中E-cadherin和DAPK基因启动子异常甲基化的研究

目的:检测胃癌中死亡相关蛋白激酶(death-associated protein kinase,DAPK)基因和上皮钙粘蛋白(epithelial cadherin,E-cadherin)基因启动子区CpG岛甲基化状态,并探讨两个基因甲基化改变的特点及其与临床病理特征、患者一般资料之间的关系.方法:采用目前常用的甲基化特异性PCR(Methylation-specific PCR.MSP)方法检测4l例胃癌组织和20例正常对照组织中DAPK、E-cadherin基因启动子区甲基化状态并进行统计分析.结果:41例胃癌组织中DAPK、E-cadherin基因启动子区甲基化阳性率分别为68.3%(28/41)和46.3%(19/41),20例正常时照组织中未检测到DAPK、E-cadherin基因启动子区发生甲基化,两个基因在胃癌组织中的甲基化率明显高于正常对照组织(P<0.05),但DAPK和E-cadherin基因启动子甲基化在胃癌的发生中无协同性(相关性和一致性).胃癌组织中一个基因发生甲基化的检出率为78.0%(32/41);胃癌组织中DAPK基因启动子区甲基化与淋巴结转移、分化程度相关(P<0.05),而E-cadherin基因启动子区甲基化则与淋巴结转移和浸润深度有相关性(P<0.05).两个基因启动子区异常甲基化与被检查者肿瘤的大小、肿瘤的部位等临床病理特征以及被检者的性别、年龄不具有相关性.结论:DAPK、E-eadherin基因启动子区甲基化是胃癌发生、发展过程中的频发事件,通过检测胃粘膜组织中两个基因启动子区甲基化状况,可能会对胃癌的早期诊断及判断预后提供一定的参考价值;联合检测两个基因甲基化状态优于各单个基因检测.     

肝癌细胞系中肝癌转移相关候选基因启动子区域CpG岛甲基化和表达水平的相关性研究

背景与目的：DNA甲基化被认为是反映细胞内DNA转录状态的重要表观遗传学标记。本研究旨在对启动子区域CpG岛的甲基化与基因转录水平的相关性进行评估。方法：采用甲基化特异性PCR的方法确定7个与肝癌转移相关的候选基因的启动子区域在6个肝细胞系(包括5个肝癌源性的)中的甲基化状态,并通过半定量PCR的方法确定6个基因稳定态的mRNA水平。结果：仅有纯合和杂合去甲基化的基因状态得到发现。RT-PCR分析表明除了OXCT基因在其处于杂合去甲基化状态的HepG2和HCCLM3细胞中不表达,在其他的情况下,7个候选基因均有表达。讨论：本研究中的7个肝癌转移相关基因的甲基化状态仅在细胞系中部分的反映了基因的转录状态,提示其它转录调控机制的存在。     

上皮性卵巢癌组织中WWOX基因启动子区域CpG岛的甲基化状态及临床意义

目的研究上皮性卵巢癌组织中WWOX基因启动子区CpG岛的甲基化状态,并分析WWOX基因的甲基化与上皮性卵巢癌的临床病理指标之间的关系。方法采用甲基化特异性PCR(methylation specific polymerase chain reaction,MSP)方法检测48例上皮性卵巢癌、18例卵巢交界性上皮性肿瘤、26例卵巢良性上皮性肿瘤及33例正常卵巢组织中WWOX基因CpG岛甲基化状态。结果上皮性卵巢癌、卵巢交界性上皮性肿瘤、卵巢良性上皮性肿瘤组织中WWOX基因启动子区CpG岛甲基化率分别为43.75%、26.32%、3.84%,正常卵巢组织中未检测到WWOX基因CpG岛甲基化。上皮性卵巢癌组织中WWOX基因CpG岛的甲基化率明显高于其他卵巢组织,差异有统计学意义(P<0.01)。晚期(Ⅲ期、Ⅳ期)上皮性卵巢癌组织中WWOX基因CpG岛的甲基化率高于早期(Ⅰ期、Ⅱ期)上皮性卵巢癌组织,差异有统计学意义(P<0.05)。结论 上皮性卵巢癌组织中广泛存在着WWOX基因启动子区CpG岛甲基化,可能是导致WWOX基因失活的重要机制。WWOX基因的异常甲基化可能与上皮性卵巢癌的发生发展密切相关,其可能成为上皮性卵巢癌的早期诊断和评估预后的重要指标。     

Aberrant methylation and silencing of ARHI,an imprinted tumor suppressor gene in which the function is lost in breast cancers

ARHI is a maternally imprinted tumor suppressor gene that maps to a site on chromosome 1p31 where loss of heterozygosity has been observed in 40% of human breast and ovarian cancers. ARHI is expressed in normal ovarian and breast epithelial cells, but ARHI expression is lost in a majority of ovarian and breast cancers. Expression of ARHI from the paternal allele can be down-regulated by multiple mechanisms in addition to loss of heterozygosity. This article explores the role of DNA methylation in silencing ARHI expression. There are three CpG islands in the ARHI gene. CpG islands I and II are located in the promoter region, whereas CpG island III is located in the coding region. Consistent with imprinting, we have found that all three CpG islands were partially methylated in normal human breast epithelial cells. Additional confirmation of imprinting has been obtained by studying DNA methylation and ARHI expression in murine A9 cells that carry either the maternal or the paternal copy of human chromosome 1. All three CpG islands were methylated, and ARHI was not expressed in A9 cells that contained the maternal allele. Conversely, CpG islands were not methylated and ARHI was expressed in A9 cells that contained the paternal allele of human chromosome 1. Aberrant methylation was found in several breast cancer cell lines that exhibited decreased ARHI expression. Hypermethylation was detected in 67% (6 of 9) of breast cancer cell lines at CpG island I, 33% (3 of 9) at CpG island II, and 56% (5 of 9) at CpG island III. Hypomethylation was observed in 44% (4 of 9) of breast cancer cell lines at CpG island II. When methylation of CpG islands was studied in 20 surgical specimens, hypermethylation was not observed in CpG island I, but 3 of 20 cases exhibited hypermethylation in CpG island II (15%), and 4 of 20 cases had hypermethylation in CpG island III (20%). Treatment with 5-aza-2'-deoxycytidine, a methyltransferase inhibitor, could reverse aberrant hypermethylation of CpG island I, II and III and partially restore ARHI expression in some, but not all of the cell lines. Treatment with 5-aza-2'-deoxycytidine partially reactivated ARHI expression in cell lines with hypermethylation of CpG islands I and II but not in cell lines with partial methylation or hypomethylation of these CpG islands. To test the impact of CpG island methylation on ARHI promoter activity more directly, constructs were prepared with the ARHI promoter linked to a luciferase reporter and transfected into SKBr3 and human embryo kidney 293 cells. Methylation of the entire construct destroyed promoter activity. Selective methylation of CpG island II alone or in combination with CpG island I also abolished ARHI promoter activity. Methylation of CpG I alone partially inhibited promoter activity of ARHI. Thus, hypermethylation of CpG island II in the promoter region of ARHI is associated with the complete loss of ARHI expression in breast cancer cells. Other epigenetic modifications such as hypermethylation in CpG island III may also contribute to the loss of ARHI expression.     

胃癌环氧化酶-2 、hMLH1 及hMSH2 微卫星不稳定与基因调控的关系

 目的 检测临床手术切除43例胃癌及相应正常组织COX-2、hMLH1和hMSH2微卫星不稳定状态MSI及三种基因启动子甲基化情况，并进一步探讨它们与胃癌发生的关系。方法 采用聚合酶链反应（PCR）技术检测5个位点的MSI状态；甲基化特异性PCR（Methylation specific PCR，MSP）方法检测胃癌及正常组织COX-2、hMLH1及hMSH2三种基因启动子CpG岛甲基化状态。结果 43例胃癌中MSI总检出率为48．84％（21／43），五个位点的MSI检出率无显著差别。COX-2和hMLH1基因启动子CpG岛甲基化在43例胃癌中分别有8例和13例，正常组织中未检测到。hMSH2基因启动子CpG岛在胃癌及正常组织中均未检测到甲基化。在MSI-H组hMLH1基因启动子CpG岛甲基化率显著高于MSS组（P〈0．01）；而在MSI-H和MSI-L组间以及MSI-L和MSS无差别。MSI-H组中COX-2基因启动子CpG岛甲基化8例，且有7例胃癌同时出现hMLH1和COX-2基因启动子CpG岛甲基化。结论 在MSI胃癌（尤其是MSI-H型胃癌）的发生、发展过程中可能同时出现了hMLH1和COX-2基因启动子CpG岛的甲基化（即表型遗传修饰）。MSI胃癌hMLH1基因启动子CpG岛甲基化率高于MSS胃癌，提示检测hMLH1基因启动子CpG岛甲基化对于判断肿瘤类型有一定意义。     

Detection of methylated apoptosis-associated genes in urine sediments of bladder cancer patients.

PURPOSE: There is increasing evidence for a fundamental role for epigenetic silencing of apoptotic pathways in cancer. Changes in DNA methylation can be detected with a high degree of sensitivity, so we used the MethyLight assay to determine how methylation patterns of apoptosis-associated genes change during bladder carcinogenesis and whether DNA methylation could be detected in urine sediments. EXPERIMENTAL DESIGN: We analyzed the methylation status of the 5' regions of 12 apoptosis-associated genes (ARF, FADD, TNFRSF21, BAX, LITAF, DAPK, TMS-1, BCL2, RASSF1A, TERT, TNFRSF25, and EDNRB) in 18 bladder cancer cell lines, 127 bladder cancer samples, and 37 samples of adjacent normal bladder mucosa using the quantitative MethyLight assay. We also analyzed the methylation status in urine sediments of 20 cancer-free volunteers and 37 bladder cancer patients. RESULTS: The 5' regions of DAPK, BCL2, TERT, RASSFIA, and TNFRSF25 showed significant increases in methylation levels when compared with nonmalignant adjacent tissue (P < or = 0.01). Methylation levels of BCL2 were significantly associated with tumor staging and grading (P < or = 0.01), whereas methylation levels of RASSF1A and ARF were only associated with tumor stage (P < or = 0.04), and TERT methylation and EDNRB methylation were predictors of tumor grade (P < or = 0.02). To investigate clinical usefulness for noninvasive bladder cancer detection, we further analyzed the methylation status of the markers in urine samples of patients with bladder cancer. Methylation of DAPK, BCL2, and TERT in urine sediment DNA from bladder cancer patients was detected in the majority of samples (78%), whereas they were unmethylated in the urine sediment DNA from age-matched cancer-free individuals. CONCLUSIONS: Our results indicate that methylation of the 5' region of apoptosis-associated genes is a common finding in patients with bladder carcinoma. The ability to detect methylation not only in bladder tissue, but also in urine sediments, suggests that methylation markers are promising tools for noninvasive detection of bladder cancers. Our results also indicate that some methylation markers, such as those in regions of RASSF1A and TNFRSF25, might be of limited use for detection because they are also methylated in normal bladder tissues.     

Cell type-specific methylation of an intronic CpG island controls expression of the MCJ gene

Over 50% of human genes are associated with CpG islands and DNA methylation within such CpG islands has been clearly correlated with inhibition of expression. Whereas changes in DNA methylation play a key role in a number of human diseases, in particular cancer, in normal DNA CpG islands are nearly always methylation free, regardless of the expression status of the associated gene. Only limited evidence supports a role for DNA methylation in controlling tissue-specific expression in adult somatic tissue. Loss of expression of the MCJ gene has previously been linked to increased chemotherapeutic drug resistance in ovarian cancer. We report that loss of expression of MCJ in drug-resistant ovarian cancer cell lines depends on methylation of a CpG island within its first exon, but is independent of methylation within the promoter region. Furthermore, cell type-specific expression of the MCJ gene in normal cells also depends on the methylation status of the CpG island within its first exon. The MCJ CpG island is methylated and the gene is not expressed in cells of epithelial origin, but unmethylated and expressed in cells of lymphocyte or fibroblast origin. Chromatin immunoprecipitation assays determined that MCJ CpG island methylation was associated with loss of histone acetylation in ovarian epithelial cells compared with unmethylated fibroblast cells. Reduced acetylation was observed not only within the CpG island, but also within the promoter region, suggesting that CpG island methylation may direct alterations in chromatin structure within the promoter region, leading to gene inactivation.     

CpG island hypermethylation and tumor suppressor genes: a booming present,a brighter future

We have come a long way since the first reports of the existence of aberrant DNA methylation in human cancer. Hypermethylation of CpG islands located in the promoter regions of tumor suppressor genes is now firmly established as an important mechanism for gene inactivation. CpG island hypermethylation has been described in almost every tumor type. Many cellular pathways are inactivated by this type of epigenetic lesion: DNA repair (hMLH1, MGMT), cell cycle (p16(INK4a), p15(INK4b), p14(ARF)), apoptosis (DAPK), cell adherence (CDH1, CDH13), detoxification (GSTP1), etc em leader However, we still know little of the mechanisms of aberrant methylation and why certain genes are selected over others. Hypermethylation is not an isolated layer of epigenetic control, but is linked to the other pieces of the puzzle such as methyl-binding proteins, DNA methyltransferases and histone deacetylase, but our understanding of the degree of specificity of these epigenetic layers in the silencing of specific tumor suppressor genes remains incomplete. The explosion of user-friendly technologies has given rise to a rapidly increasing list of hypermethylated genes. Careful functional and genetic studies are necessary to determine which hypermethylation events are truly relevant for human tumorigenesis. The development of CpG island hypermethylation profiles for every form of human tumors has yielded valuable pilot clinical data in monitoring and treating cancer patients based in our knowledge of DNA methylation. Basic and translational will both be needed in the near future to fully understand the mechanisms, roles and uses of CpG island hypermethylation in human cancer. The expectations are high.