食管鳞癌组织p16基因调控区甲基化及其蛋白表达研究

目的探讨p16基因在食管癌变过程中表达缺失与其启动子区甲基化的关系。方法采用MSP免疫组化方法,检测环太行山地区45例食管鳞癌患者癌组织p16基因启动子区甲基化状态及蛋白表达情况。结果p16基因在癌组织中表达异常41例（91．1％）,间变组织中表达异常38例（84．4％）,发生纯合型甲基化的组织分别为33例（73．3％）（癌组织）和32例（71．1％）（间变组织）,而其周围正常组织26例（57．8％）均发生了p16启动子区的杂合型甲基化。p16基因纯合型甲基化与癌组织、间变组织、p16蛋白表达缺失相关（P〈0．05）。结论该地区食管癌组织p16基因在癌前病变中p16启动子区即发生了纯合型甲基化、食管癌变的早期事件。p16基因启动子区甲基化可单独影响p16蛋白的正常表达。     

新疆哈萨克族食管癌中Cdc42基因启动子区甲基化与其mRNA表达改变的研究

目的研究新疆哈萨克族食管癌中Cdc42基因启动子区甲基化状态与其mRNA表达改变的关系。方法用RT—PCR方法测定mRNA表达,甲基化特异PCR方法检测DNA启动子区甲基化状态。结果在20例癌组织中,有16例表达阳性,占80％,20例癌旁组织中有13例表达,占65％,其中癌组织表达量明显高于癌旁组织的有10例,占50％,癌旁组织表达量高于癌组织的有5例,占25％。肿瘤组织和正常组织该基因启动子区见甲基化条带,未见非甲基化条带。结论Cdc42基因在肿瘤组织和正常组织均表现为高甲基化状态,新疆哈萨克族食管癌中Cdc42基因mRNA表达增强可能与该基因的甲基化状态没有直接关系,另存在其他机制,有待进一步研究。     

上消化道癌肿中runx3基因甲基化研究

runx3是胃癌中新发现的抑癌基因。国外至少40％的胃癌组织中检测到runx3基因启动子区高甲基化，此种高甲基化状态直接导致基因静默，表达缺失。runx3启动子甲基化具有很高的肿瘤特异性，有望成为胃癌诊断的早期标记。鉴于runx3启动子甲基化与前肠来源组织肿瘤密切相关，我们研究runx3在我国食管鳞癌、贲门癌和胃癌中的甲基化状态及相应mRNA表达水平，探索其在这些肿瘤发生中的作用。     

CHFR、CDKN2A甲基化在食管鳞癌KYSE150、KYSE180细胞系放射抵抗中的作用

目的探讨抑癌基因CHFR、CDKN2A甲基化在食管鳞癌放射抵抗中的作用。方法食管鳞癌细胞系KYSE150、KYSE180经辐照处理后形成稳定的放射抵抗细胞克隆KYSE150-8 Gy,KYSE180-8 Gy,对原始细胞系和放射抵抗细胞系抑癌基因CHFR、CDKN2A进行DNA提取、甲基化处理及焦磷酸测序,再对样本mRNA进行提取并采用实时聚合酶链反应(RT-PCR)检测其表达。并配对比较细胞系增殖能力。结果 KYSE150、KYSE180及KYSE150-8 Gy、KYSE180-8 Gy细胞系均有CHFR及CDKN2A基因DNA甲基化现象,且放射抵抗细胞系DNA甲基化程度高于原始细胞系,相应基因表达低于原始细胞系,且放射抵抗细胞系增殖能力显著高于原始细胞系。结论 CHFR、CDKN2A基因高甲基化导致肿瘤抑制功能的丧失,使食管鳞癌细胞DNA修复能力和抗凋亡能力显著加强,并因此抗拒了放射线的灭活,同时增强了肿瘤的增殖能力。     

食管鳞癌细胞株金属硫蛋白3基因CpG岛超甲基化的临床意义

目的 探讨金属硫蛋白3(MT-3)基因CpG岛超甲基化与食管鳞状细胞癌的关系.方法选取TE-1、TE-13、TTN和ECA-109四种食管鳞癌细胞株,用甲基化特异性聚合酶链反应和逆转录聚合酶链反应技术,在5-氮2'-脱氧胞苷(5-Aza-CdR)处理前后,对各细胞株的MT3基因CpG岛超甲基化及mRNA表达进行比较.结果 四种食管鳞状细胞癌细胞株的MT3基因均存在不同程度的CpG岛超甲基化.5-aza-CdR处理后超甲基化状态解除,mRNA表达明显提高(P均<0.05).结论 食管鳞状细胞癌细胞株中MT3基因CpG岛超甲基化可抑制其mR-NA表达:超甲基化解除后MT3基因的mRNA表达相应升高.     

急性白血病ZO-1基因表达与甲基化调控关系的研究

目的探讨人急性白血病细胞系与正常骨髓细胞中ZO-1基因启动子区甲基化状态的差异及其与基因表达的关系。方法应用反转录聚合酶链反应的方法观察3种人白血病细胞株HL60、NK92、Molt4及正常人骨髓有核细胞中ZO-1基因的表达情况;应用甲基化特异性聚合酶链反应的方法分别检测其ZO-1基因启动子区的甲基化状态;应用去甲基化药物处理HL-60细胞,观察处理后ZO-1基因甲基化状态及基因表达的变化。结果在10例正常骨髓细胞均可发现ZO-1基因表达,而在3种白血病细胞系中未见其表达;正常骨髓细胞中ZO-1基因启动子区无甲基化。而在3种白血病细胞中呈完全甲基化;应用去甲基化药物处理HL-60细胞使其ZO-1基因启动子区去甲基化,可重新诱导ZO-1基因的表达。结论ZO-1基因的表达受甲基化状态调控,ZO-1基因可能与白血病发生相关。     

应用全基因组甲基化芯片筛选结直肠腺瘤基因启动子区甲基化标志物

目的应用全基因组甲基化芯片筛选结直肠腺瘤基因启动子区甲基化标志物。方法选择2013年1月至2014年12月在广西壮族自治区人民医院及广西医科大学第一附属医院住院的进展期结直肠腺瘤患者9例(腺瘤组),另选择经肠镜排除炎症性肠疾病、癌前病变及癌的患者20例作为对照组。腺瘤组于内镜下切除结直肠腺瘤标本(直径≥2 cm),对照组取结直肠黏膜标本(结肠黏膜13例,直肠黏膜7例)。提取组织DNA,应用全基因组甲基化芯片进行甲基化检测,通过生物信息学分析筛选差异甲基化基因启动子区甲基化标志物。结果以Δβ≥|0.4|,在基因启动子区共发现1 870个差异甲基化标志物,1 524个为高甲基化标志物,346个为低甲基化标志物,其中包含929个启动子差异甲基化基因。GO分析结果显示,启动子差异甲基化基因主要在化学性突触传递、神经系统发育、细胞外基质组织、细胞外基质结构成分、RNA聚合酶Ⅱ调控区序列特异性DNA结合、序列特异性DNA结合、质膜、蛋白质类细胞外基质、细胞膜等注释条目中出现富集。KEGG_Pathyway分析显示,启动子差异甲基化基因主要参与了神经活性的配体-受体相互作用、尼古...     

质子泵抑制剂治疗对Barrett食管APC基因启动子区甲基化的影响

背景：Barrett食管（BE）是食管腺癌的癌前病变,与食管腺癌的发生密切相关,已成为近年来的研究热点。目的：观察质子泵抑制剂（PPI）埃索美拉唑对BE患者抑癌基因APC表达及其启动子区甲基化的影响。方法：以甲基化特异性聚合酶链反应（PCR）和实时荧光定量PCR观察69例BE患者APC基因启动子区甲基化阳性率和APCmRNA表达在埃索美拉唑治疗前后的变化。分析治疗前APC基因启动子区甲基化状态与BE临床病理特征的关系。结果：埃索美拉唑治疗前,APC基因启动子区甲基化阳性率显著高于治疗后（42．0％对17．4％,P=0．007）。治疗前．长段BE的APC甲基化阳性率显著高于短段BE（46．8％对31．8％,P=0．032）;内镜下食管炎洛杉矶分类A级和B级者的APC甲基化阳性率显著低于C级和D级（19．0％对52．1％,P=0．046）;Ⅰ、Ⅱ、Ⅲ型BE间APC甲基化阳性率无明显差异（P=0．061）。埃索美拉唑治疗后,BE上皮APCmRNA表达量较治疗前显著增加（19．5±0．4对6．5±2．3,P=0．000）。结论：埃索美拉唑可抑制BE患者APC基因启动子区甲基化,增加抑癌基因APC表达。     

肺癌组织中RKIP基因启动子区甲基化状态观察

目的观察肺癌组织中Raf激酶抑制蛋白（RKIP）基因启动子区甲基化状态变化,探讨其与肺癌临床病理特征的关系。方法采用RT-PCR和甲基化特异性PCR法（MSP）分析肺癌及相应癌旁肺组织中RKIP基因表达情况及其启动子区甲基化状态。结果肺癌组织中RKIP基因启动子区甲基化率为45．8％（27／56）,明显高于癌旁肺组织的13．3％（2／56）,P〈0．05。所有甲基化的肺癌组织中RKIP基因均无表达。有淋巴结转移的43例肺癌组织中,27例RKIP基因启动子甲基化;无淋巴结转移的40例中,11例RKIP基因启动子甲基化（P〈0．05）。结论肺癌组织中RKIP基因失表达与其启动子区甲基化有关,这可能是肺癌发生发展以及转移的原因之一。     

胃癌细胞PTEN基因启动子区甲基化与蛋白表达的关系及意义

目的探讨胃癌细胞中抑癌基因PTEN5’启动子区CpG岛甲基化状态与其蛋白表达的关系。方法采用甲基化特异性聚合酶链反应（MSP）方法检测不同分化程度的胃癌细胞（HGC-27，MGC-803，BGC-823，SGC-7901）中PTEN基因启动子区域甲基化状态。并通过Western blot法检测该4种细胞中PTEN蛋白的表达。结果除SGC-7901外，其他三种胃癌细胞PTEN基因都有不同程度的甲基化，并随着胃癌细胞分化程度的降低。PTEN启动子区甲基化逐渐增强（P〈0．01）；PTEN蛋白表达逐渐减弱（P〈0．01）。PTEN蛋白表达与其启动子区高甲基化之间呈负相关。结论PTEN基因启动子区异常甲基化可能导致该基因失活，使其蛋白表达减少甚至缺失，这可能是导致胃癌发生、发展的重要机制之一。     

Methylation of TIMP3 in esophageal squamous cell carcinoma

AIM： To measure the frequency of DNA methylation of the tissue inhibitor of metalloproteinase 3 （TIMP3） promoter and relate this to any change of gene expression in esophageal squamous cell carcinoma in patients from a region of high incidence in China. METHODS： Cancer cell lines were treated with or without the demethylating reagent 5-aza-2′-deoxycytidine. Methylation of the TIMP3 promoter was assessed in three regions by melt curve analysis and its expression was assessed by real-time RT-PCR. Tumors and proximal resection margins were obtained from 64 patients with esophageal squamous cell carcinoma from a region of high incidence in China. Methylation was assessed by melt curve analysis and expression by immunohistochemistry.
RESULTS： Methylation in one of the three promoter regions assessed correlated with gene silencing in esophageal cell lines. A degree of methylation of TIMP3 was found in only four esophageal squamous cell carcinomas, and partial loss of TIMP3 protein expression in just one.
CONCLUSION： Methylation and loss of expression of TIMP3 occurs infrequently in esophageal squamous cell carcinoma in a region of high incidence in China.     

Downregulation of retinoic acid receptor-β2expression is linked to aberrant methylation in esophageal squamous cell carcinoma cell lines

AIM: To study the role of hypermethylation in the loss ofretinoic acid receptorβ2(RARβ2) in esophageal squamous cell carcinoma (ESCC).METHODS: The role of hypermethylation in RAR,β2 gene silencing in 6 ESCC cell lines was determined by methylationspecific PCR (MSP), and its methylation status was compared with RARβ2 mRNA expression by RT-PCR. The MSP results were confirmed by bisulfite sequencing of RARβ2promoter regions. RESULTS: Methylation was detected in 4 of the 6 cell lines, and the expression of RARβ2was markedly downregulated in 3 of the 4 methylated cell lines. The expression of RARβ2was restored in one RARβ2-downregulated cell line with the partial demethylation of promoter region of RARβ after 5aza-2'-deoxycytidine (5-aza-dc) treatment.CONCLUSION: The methylation of the 5' region may play an important role in the downregulation of RARβ2 in someESCC cell lines, suggesting that multiple mechanisms contribute to the loss of RARβ2expression in ESCC cell lines. This study may have clinical applications for treatment and prevention of ESCC.     

Expression of OCT4 in human esophageal squamous cell carcinoma is significantly associated with poorer prognosis

AIM: To explore the expression pattern of OCT4 in human esophageal squamous cell carcinoma and its significance in diagnosis and prognosis.METHODS: Using real-time polymerase chain reaction (PCR), Western blotting, immunocytochemistry and immunohistochemistry, the expression of OCT4 in three esophageal squamous cancer cell lines, KYSE70, KYSE140 and KYSE450, was characterized. OCT4 expression was investigated in a series of 153 esophageal squamous cell carcinoma samples using immunohistochemistry and explored its association with clinicopathological features.RESULTS: Immunohistochemically, OCT4 positive immunostaining was observed in cancer cell nuclei. OCT4 was variably expressed in three esophageal squamous cancer cell lines. Among 153 specimens, 105 (68.7%) were negative or weakly positive for OCT4 staining; 21 (13.7%) were moderately positive and 27 (17.6%) were strongly positive. Higher expression level of OCT4 was significantly associated with higher histological grade (P < 0.001) and poor clinic outcome (P < 0.001).CONCLUSION: The expression of OCT4 enables the tumor to have a higher degree of stemness, which in turn results in a poorer clinical outcome for patients with esophageal squamous cell carcinoma.     

Downregulation of retinoic acid receptor-β2expression is linked to aberrant methylation in esophageal squamous cell carcinoma cell lines

AIM:To study the role of hypermethylation in the loss of retinoic acid receptor β2(RARβ2) in esophageal squamous cell carcinoma (ESCC).METHODS:The role of hypermethylation in RARβ2 gene silencing in 6 ESCC cell lines was determined by methylation-specific PCR (MSP),and its methylation status was compared with RARβ2 mRNA expression by RT-PCR.The MSP results were confirmed by bisulfite sequencing of RARβ2promoter regions.RESULTS:Methylation was detected in 4 of the 6 cell lines,and the expression of RARβ2 was markedly downregulated in 3 of the 4 methylated cell lines. The expression of RARβ2 was restored in one RARβ2-downregulated cell line with the partial demethylation of promoter region of RARβ2 after 5-aza-2′-deoxycytidine (5-aza-dc) treatment.CONCLUSION:The methylation of the 5′ region may play an important role in the downregulation of RARβ2 in some ESCC cell lines, suggesting that multiple mechanisms contribute to the loss of RARβ2expression in ESCC cell lines.This study may have clinical applications for treatment and prevention of ESCC.     

Demethylation-mediated upregulation of melanoma-associated antigen-A11 correlates with malignant progression of esophageal squamous cell carcinoma

BackgroundThe expression and methylation status of oncogenes are closely related to the onset and progression of cancer.AimsTo explore the role and methylation status of melanoma-associated antigen-A11 in the pathogenesis of esophageal squamous cell carcinoma.Methods116 esophageal squamous cell carcinoma patients with tumor tissues and corresponding adjacent normal tissues were obtained. The expression level and methylation status of melanoma-associated antigen-A11 in esophageal cancer cell lines and esophageal squamous cell carcinoma tissues were determined respectively.ResultsSignificant up-regulation of melanoma-associated antigen-A11 was detected in esophageal cancer cell lines and esophageal squamous cell carcinoma tissues. Up-regulation of melanoma-associated antigen-A11 contributed to proliferation and invasion in cancer cells. Hypomethylation of the CpG site was associated with pathological differentiation, clinical stage, tumor size, lymph node metastasis and distant metastasis. Esophageal squamous cell carcinoma patients in stage III and IV, with high expression of melanoma-associated antigen-A11 or hypomethylation of the CpG site within the promoter demonstrated poor survival.ConclusionMelanoma-associated antigen-A11 is up-regulated in esophageal squamous cell carcinoma at least partly by hypomethylation of the CpG site within the promoter and this hypomethylation may affect the prognosis of esophageal squamous cell carcinoma patients.     

Expression of ECRG4, a novel esophageal cancer－related gene,downregulated by CpG island hypermethylation in human esophageal squamous cell carcinoma

AIM: To study the mechanisms responsible for inactivation of a novel esophageal cancer related gene 4 (ECRG4) in esophageal squamous cell carcinoma (ESCC). METHODS: A pair of primers was designed to amplify a 220 bp fragment, which contains 16 CpG sites in the core promoter region of the ECRG 4 gene. PCR products of bisulfite-modified CpG islands were analyzed by denaturing high-performance liquid chromatography (DHPLC), which were confirmed by DNA sequencing. The methylation status of ECRG 4 promoter in 20 cases of esophageal cancer and the adjacent normal tissues, 5 human tumor cell lines (esophageal cancer cell line-NEC, EC109, EC9706; gastric cancer cell line- GLC; human embryo kidney cell line-Hek293) and 2 normal esophagus tissues were detected. The expression level of the ECRG 4 gene in these samples was examined by RT-PCR. RESULTS: The expression level of ECRG 4 gene was varied. Of 20 esophageal cancer tissues, nine were unexpressed, six were lowly expressed and five were highly expressed compared with the adjacent tissues and the 2 normal esophageal epithelia. In addition, 4 out of the 5 human cell lines were also unexpressed. A high frequency of methylation was revealed in 12 (8 unexpressed and 4 lowly expressed) of the 15 (80 %) downregulated cancer tissues and 3 of the 4 unexpressed cell lines. No methylation peak was observed in the two highly expressed normal esophageal epithelia and the methylation frequency was low (3/20) among the 20 cases in the highly expressed adjacent tissues. The methylation status of the samples was consistent with the result of DNA sequencing. CONCLUSION: These results indicate that the inactivation of ECRG 4 gene by hypermethylation is a frequent molecular event in ESCC and may be involved in the carcinogenesis of this cancer.     

CHD5基因在食管癌中的表观遗传学改变

目的:研究食管癌发病过程中染色质解旋酶DNA结合蛋白5(Chromodomain helicase DNA-binding protein5,CHD5)基因表观遗传学改变,探讨CHD5基因甲基化作为食管癌诊断标志物的可行性.方法:用甲基化特异性聚合酶链反应(methylation specific PCR,MSP)检测72例食管癌组织及成对癌旁组织,9例正常食管黏膜组织及4株食管癌细胞系中CHD5基因的甲基化状态,并用逆转录聚合酶链式反应(RT-PCR)检测CHD5基因在上述食管癌细胞系的表达.结果:69%(50/72)食管癌组织发生CHD5基因启动子区甲基化,32%(23/72)癌旁组织发生甲基化,差异具有统计学意义(χ2=20.254,P<0.05).9例食管正常组织未发生甲基化,2株食管癌细胞系中由于基因启动子区甲基化导致CHD5基因表达缺失,经5-aza-deoxycytidine处理96h后CHD5重新表达.结论:食管癌中CHD5基因频繁发生甲基化,表观遗传学改变是其基因表达的重要调节机制,CHD5基因甲基化有可能作为食管癌诊断的标志物.