Relationship between aberrant methylation of FAS promoter and biological behavior of bladder urothelial carcinoma

This study examined the promoter methylation of APO-1/CD95 (Fas) gene in bladder urothelial carcinoma and analyzed the relationship between the Fas promoter methylation and the biological behavior of b...     

METHYLATION PATTERN OF LRP15 GENE IN LEUKEMIA

Objective To investigate the methylation status of LRP15 gene in acute leukemia (AL) patients and its role in the tumorigenesis. Methods The methylation of LRP15 promoter and first exon of bone marrow mononuclear cells in 73 patients with AL, 10 with chronic leukemia (CL), 9 with hematological benign diseases, and 20 healthy transplantation donors was analyzed by using methylation specific polymerase chain reaction. The methylation of LRP15 gene promoter and first exon in COS7, K562, and HL60 cell lines was also assayed. Results No LRP15 gene promoter methylation was detected in COS7 cell line. LRP15 gene promoter was methylated in K562 and HL60 cell lines. No deletion of LRP15 gene was detected in all samples. In nearly all French-American-British leukemia subtypes, we found that frequency of LRP15 methylation in adult patients with AL was 71.23% (52/73). There was no detectable methylation in any of the 20 healthy donors and 8 chronic myeloid leukemia patients. The difference in frequency of LRP15 methylation between AL patients and healthy donors or CL patients (10.00%, 1/10) was significant (P<0.01). Hypermethylation of LRP15 gene was found in 57.14% (16/28) of newly diagnosed AL patients, 83.33% of relapsed AL patients respectively, which was significantly different (P<0.05). We also demonstrated LRP15 methylation in 55.56% (5/9) adults with benign hematological diseases. Conclusions LRP15 methylation changes are common abnormalities in leukemia. LRP15 is postulated to be a tumor suppressor gene.     

Methylation of Gene CHFR Promoter in Acute Leukemia Cells

In order to explore whether gene CHFR was inactivated by methylation in leukemia cells, the expression of CHFR was examined before and after treatment with demethylation agent in Molt-4, Jurkat and U937 leukemia cell lines by means of RT-PCR， The methylation of promoter in Moh-4, Jurkat and U937 cells as well as 41 acute leukemia patients was analyzed by MS-PCR. The results showed that methylation of CHFR promoter was inactivated and could be reversed by treatment with a demethylating agent in Molt 4, Jurkat and U937. CHFR promoter methylation was detected in 39 % of acute leukemia patients. There was no difference in incidence of CHFR promoter methylation between acute myeloeytie leukemia and acute lymphocytic leukemia. In conclusion, CHFR is frequently inactivated in acute leukemia and is a good candidate for the leukemia supper gene. By affecting mitotic checkpoint function, CHFR inactivation likely plays a key role in tumorigenesis in acute leukemia. Moreover, the methylation of gene CHFR appears to be a good index with which to predict the sensitivity of acute leukemia to microtubule inhibitors.     

Effect of Mono-2-ethyhexyl Phthalate on DNA Methylation in Human Prostate Cancer LNCaP Cells

Objective To evaluate whether mono(2‐ethylhexyl) phthalate(MEHP) affects genomic DNA methylation and the methylation status of some specific genes such as patched gene(PTCH) and smoothened gene(SMO) in LNCaP cells. Methods LNCaP cells were treated with MEHP(0, 1, 5, 10, and 25 μmol/L) for 3 days. An ELISA assay was preformed to detect genomic methylation, including 5‐methylcytosine(5‐mC) and 5‐hydroxymethylcytosine(5‐hmC) content. A pyrosequencing assay was applied to assess DNA methylation in PTCH and SMO gene promoters. The correlation between DNA methylation and gene expression was assessed. Results The proportion of cytosines with 5‐mC methylation in LNCaP cells was significantly decreased by MEHP(1, 5, 10, and 25 μmol/L) in a dose‐dependent manner(P 0.01). For genes in the Hedgehog pathway, there was no significant MEHP concentration‐dependent difference in the DNA methylation of PTCH and SMO. Conclusion MEHP might affect the progression of prostate cancer through its effect on global DNA methylation.     

Relationship between the Expression of RASSF1A Protein and Promoter Hypermethylation of RASSF1A Gene in Bladder Tumor

To investigate the relationship between the expression of RASSF1A protein and promoter hypermethylation of RASSF1A gene, RASSF1A protein expression was measured by Western blotting in 10 specimens of normal bladder tissues and 23 specimens of bladder transitional cell carcinoma （BTCC）. The promoter methylation in BTCC and normal bladder tissues was detected by methylation-specific PCR （MSP）. The results showed that the expression level of RASSF1A protein was significantly lower in BTCC tissues than that in normal bladder tissues. However, it was not correlated with its clinical stages and pathological grades. The frequency of promoter methylation of RASSF1A gene was higher in BTCC tissues than that in normal bladder tissues. In 14 patients with the aberrant promoter methylation, 13 showed loss or low expression of RASSF 1A protein. It is concluded that RASSF1A gene promoter methylation may contribute to the low level or loss of RASSF1A protein expression, the inactivation of RASSF1A gene and the genesis of BTCC. But, it may bear no correlation with its clinical stages and pathological grades.     

Association of E-cadherin and β-catenin with metastasis in nasopharyngeal carcinoma

Background This study was designed to detect methylation of E-cadherin gene promoter and gene mutation of β-catenin in exon 3 and their expression of protein and mRNA in primary tumor and lymph node metastatic tumor of nasopharyngeal carcinoma (NPC), and investigate the mechanism of invasion and metastasis of neoplastic cells in NPC. Methods Fourty-two fresh biopsy samples were taken from untreated NPC patients at the Affiliated Hospital of Sun Yat-sen Medical College, Sun Yat-sen University, Guangzhou, China during the period of 1999 -2002. Among them 21 were taken from primary tumors and the other 21 from lymph node metastatic tumors. The gene promoter methylation of E-cadherin was detected by methylation-specific PCR (MSP). The mutation in exon 3 of β-catenin was detected by direct sequencing analysis. RT-PCR, Western blot and immunohistochemical staining were used to detect the mRNA and protein expression patterns in both primary and metastatic tumors of NPC. Results Down-regulated expression of E-cadherin in metastatic tumor was compared with that in primary tumor. Reduced expression of E-cadherin was found to be correlated with lymph node metastatic tumor of NPC ( P = 0. 004) ; but there was no obvious correlation between primary and metastatic tumors in the expression of β-catenin (P = 0. 698). The mRNA expression level of Ecadherin in metastatic tumors decreased significantly compared with that in primary tumors. However, little change was observed in the mRNA level of β-catenin in different tumor tissues. Only 4 samples (19. 1%) displayed gene promoter methylation of E-cadherin in primary tumor and 10 samples (47. 6%) showed methylated form of E-cadherin. The gene promoter methylation of E-cadherin was more common in metastatic tumor than in primary tumor of NPC ( P =0. 024). Only 2 (4. 76% ) of the 42 samples showed mutations in exon 3 of β-catenin at 41 (T41A, ACC→GCC) and codon 47(S47T, AGT→ACT). The cytoplasmic and nuclear expression of β-catenin in tumor was not found in any samples of NPC. Conclusions The results suggest that the downregulation of E-cadherin results from the gene promoter aberrant methylation of E-cadherin and that the methylation of E-cadherin plays an important role in invasion and metastasis of tumor cells in NPC. However, β-catenin mutation is an infrequent event in NPC, and β-catenin is not a critical factor influencing the invasion and metastasis of tumor cells in NPC.     

MSP法检测胃癌的PTEN基因甲基化改变

目的:检测胃癌中抑癌基因PTEN启动子区域甲基化状况,并探讨其甲基化改变的特点与临床病理特征的关系。方法:采用甲基化特异的PCR法(MSP)检测胃癌组织及相应癌旁组织(各35例)中PTEN启动子区域甲基化状态。结果:35例癌旁正常胃组织未发现有PTEN基因启动子的甲基化,16/35例胃癌组织检测到PTEN基因启动子的甲基化,癌组织PTEN基因启动子甲基化率显著增高(P<0.05)。有淋巴结转移的19例胃癌组织中,有12例PTEN基因启动子甲基化,有淋巴结转移的PTEN基因启动子甲基化显著高于无淋巴结转移组(P<0.05)。结论:PTEN基因启动子的甲基化与胃癌的发生、转移相关。甲基化特异的PCR法(MSP)是检测胃癌抑癌基因PTEN启动子区域甲基化状况的一种较新且特异的实验方法,可用于胃癌的辅助诊断和预后判断。     

候选抑癌基因Syk启动子甲基化与胃癌转移相关

目的：探讨Syk（spleen tyrosine kinase）基因启动子甲基化在胃癌发生、转移过程中的作用及其临床意义。方法：采用RT-PCR检测61例胃癌组织、癌旁组织中SykmRNA的表达．并用甲基化特异性PCR（MSP）方法检测Syk基因启动子甲基化情况。结果：61例癌旁组织均检测到Syk基因的表达,胃癌组织有14例检测到Syk基因的表达,Syk基因在胃癌组织中表达率显著降低（P〈0．05）。61例胃癌旁组织未发现有Syk基因启动于的甲基化。而61例癌组织中有21例检测到Syk基因启动子的甲基化。癌组织Syk基因启动于甲基化率显著高于癌旁组织（P〈0．05）。有淋巴结转移的31例胃癌组织中,有17例Syk基因启动子甲基化,有淋巴结转移的Syk基因启动于甲基化姓著高于无淋巴结转移组（P〈0．05）。结论：Syk基因启动于甲基化是导致Syk基因失活的原因之一。Syk基因启动子的甲基化可能与胃癌的发生、转移有关。     

胃癌组织中Caveolin-1基因外显子2甲基化状态检测

目的：应用甲基化特异性PCR（MSP）技术检测胃癌组织中Caveotin-1基因外显子2启动子区域5’端CpG岛甲基化状况,探讨Caveolin-1基因甲基化在胃癌发生发展中的作用．方法：收集30例胃癌组织和6例距肿瘤5cm以上的癌旁正常胃组织,运用标准蛋白酶K消化、酚-氯仿抽提法提取组织中基因组DNA,采用CpGenome DNA Modification Kit对DNA进行修饰后以甲基化特异性引物及非甲基化引物进行PCR,通过琼脂糖凝胶电泳及产物测序判定结果．结果：6例癌旁正常胃组织Caveolin-1基因外显子2启动子区域5＇端CpG岛均为甲基化阴性．30例胃癌组织中有27例甲基化阳性,甲基化率为90％（27／30）．其中16例胃癌组织（53．3％）仅有甲基化引物扩增出目的条带,表现为完全甲基化;11例胃癌组织（36．7％）甲基化与非甲基化引物均扩增出目的条带,表现为部分甲基化．统计结果显示胃癌组织中Caveolin-1基因外显子2启动子区域甲基化率显著高于癌旁正常胃组织．结论：胃癌组织中存在Caveolin-1基因外显子2启动子区域高甲基化,且可能参与胃癌的早期过程．     

甲基化调控microRNA表达影响胰腺癌细胞增殖、迁移、侵袭的研究

目的 研究基因启动子区甲基化对胰腺癌相关microRNA（miR34a、miR34b、miR148a、miR203a）表达水平的调控,及其对胰腺癌细胞增殖、迁移、侵袭能力的影响。方法 通过5-氮杂-2′-脱氧胞苷（5-Aza-CdR)去甲基化处理胰腺癌细胞MIAPaca-2,使用甲基化特异性PCR (methylation-specific PCR,MSP)法检测60 μmol/L 5-Aza-CdR处理组及0 μmol/L对照组 MIAPaca-2细胞目标microRNA启动子甲基化水平的变化;用荧光实时定量PCR检测处理组及对照组目标microRNA表达水平的改变;CCK-8法、划痕实验以及Transwell法检测胰腺癌细胞去甲基化处理后处理组和对照组增殖、迁移、侵袭能力的变化。结果 MSP法结果显示处理组较未处理组目标microRNA甲基化M条带灰度值减弱,非甲基化U条带灰度值增强,处理组目标microRNA启动子甲基化程度较对照组减弱。荧光实时定量PCR结果显示处理组较未处理组目标microRNA相对表达量升高（ P<0.05）,处理组microRNA的表达水平随去甲基化处理而升高。CCK-8法显示随着药物处理浓度的增加,处理组细胞抑制率增高,去甲基化处理抑制了胰腺癌细胞的增殖能力。划痕实验结果显示处理组较未处理组细胞伤口愈合率降低（ P<0.01）,去甲基化处理降低了胰腺癌细胞的迁移能力。Transwell法结果显示处理组较未处理组穿膜细胞数减少（ P<0.01）, 去甲基化处理降低了胰腺癌细胞的侵袭能力。结论 肿瘤细胞去甲基化处理,导致4种目标microRNA高表达,抑制了胰腺癌细胞的增殖、迁移和侵袭能力。     

microRNA-34a在肺癌细胞凋亡中的作用

目的 探讨microRNA-34a在肺癌细胞凋亡中的作用。 方法 将A549肺癌细胞株分为3组:microRNA-34a转染组、对照组和未转染组。分析microRNA-34a在A549肺癌细胞中的表达,microRNA-34a对A549肺癌细胞生长周期、细胞增殖、细胞凋亡的影响,microRNA-34a对A549肺癌细胞Bcl-2、P53和C-MYC蛋白以及mRNA表达的影响。 结果 miRNA-34a转染组microRNA-34a的表达明显高于对照组(P<0.05)。miRNA-34a转染组G₀/G₁细胞明显高于对照组和未转染组(P<0.05)。miRNA-34a转染组48 h和96 h的增殖率明显低于对照组和未转染组(P<0.05)。miRNA-34a转染组的细胞凋亡明显高于对照组和未转染组(P<0.05)。miRNA-34a转染组的Bcl-2蛋白和C-MYC蛋白表达水平明显低于对照组(P<0.05);miRNA-34a转染组的P53蛋白表达水平明显高于对照组(P<0.05)。miRNA-34a转染组的Bcl-2 mRNA和C-MYC mRNA表达水平明显低于对照组Bcl-2 mRNA和C-MYC mRNA表达水平(P<0.05);miRNA-34a转染组的P53 mRNA表达水平明显高于对照组P53 mRNA表达水平(P<0.05)。 结论 microRNA-34a抑制A549肺癌细胞增殖,促进A549肺癌细胞的凋亡,机制可能为下调Bcl-2和C-MYC基因,上调P53基因。      

RUNX3启动子甲基化与胃癌发生发展的关系

目的检测胃癌RUNX3基因启动子区域甲基化情况,探讨RUNX3基因在胃癌发生和发展过程中的意义。方法采用DNA甲基化特异性聚合酶链反应[methylation-specific polymerase chain reaction,PCR（MSP）]技术对30例胃癌患者手术切除肿瘤组织及其癌旁组织RUNX3基因启动子区域甲基化进行检测。结果 RUNX3基因甲基化率在胃癌中为70.0%（21/30）,其癌旁组织中为16.7%（5/30）,有统计学差异（P〈0.05）。结论 RUNX3的甲基化可能是癌症特异性的,其启动子区甲基化与胃癌的发生、发展密切相关。     

喉鳞状细胞癌中RASSF1A基因启动子区甲基化及蛋白表达

目的：探讨RASSF1A基因启动子区甲基化与喉癌的关系。方法：运用甲基化特异性PCR,检测RASSF1A基因在48例喉癌组织、相对应癌旁组织及48例正常人外周血中的启动子区甲基化情况。用Western blotting方法检测喉癌组织、癌旁组织及正常人外周血中RASSF1A表达情况。结果：在48例喉癌组织、相对应的癌旁组织和48份正常人外周血中,RASSF1A基因启动子区分别有34例（70.83%）、11例（22.92%）和6例（12.50%）发生了甲基化, 喉癌组织甲基化程度明显高于癌旁组织和正常人外周血（P<0.05）。在48例喉癌组织中27例（56.25%）不能正常表达RASSF1A蛋白,而相对应癌旁组织中仅有8例（16.67%）,喉癌组织中RASSF1A蛋白的表达程度明显低于癌旁组织(P<0.01)。启动子区发生甲基化的34例喉癌组织中共有25例（73.53%）呈弱阳性,而7例未发生甲基化的喉癌组织中为1例（14.29%）,两组间比较差异具有显著性(P<0.05)。结论：RASSF1A基因启动子区甲基化与喉癌的发生有关,有望成为喉癌诊断的分子标志。     

候选抑癌基因syk启动子甲基化与乳腺癌发生和转移的关系

目的　探讨脾酪氨酸激酶 (spleentyrosinekinase ,syk)基因启动子甲基化与乳腺癌发生、发展过程的关系。方法　采用逆转录 聚合酶链反应 (RT PCR)检测了 4 0例乳腺癌组织、癌旁组织及15例乳腺纤维瘤组织中sykmRNA的表达 ,同时用甲基化特异性PCR(MSP)方法检测syk基因启动子甲基化情况。结果　 4 0例癌旁组织、乳腺纤维瘤组织均检测到syk基因的表达 ,乳腺癌组织有 9例检测到syk基因的表达 ,syk基因在乳腺癌组织中表达率显著降低 (P <0 .0 5 )。癌旁组织及乳腺纤维瘤组织未发现有syk基因启动子的甲基化 ,4 0例乳腺癌组织中有 17例检测到syk基因启动子的甲基化 ,癌组织syk基因启动子甲基化率显著增高 (P <0 .0 5 )。有淋巴结转移的 18例乳腺癌组织中 ,有 14例syk基因启动子甲基化 ,有淋巴结转移的syk基因启动子甲基化显著高于无淋巴结转移组 (P <0 .0 5 )。结论　syk基因启动子甲基化是导致syk基因失活的原因之一 ,syk基因启动子的甲基化可能与乳腺癌的发生、转移相关。     

上调microRNA-34a抑制胶质瘤细胞的增殖及侵袭

目的 探讨microRNA-34a(miR-34a)在胶质瘤组织中的表达情况以及对人脑胶质瘤细胞系U251增殖及侵袭的影响.方法 选取川北医学院附属医院2013年3月至2017年3月胶质瘤组织标本30例和重症脑外伤需行手术者正常脑组织标本10例作为研究对象,采用荧光定量PCR法检测miR-34a在胶质瘤组织表达情况.体外实验,将人工合成的miR-34a模拟物miR-34a mimic转染至U251细胞系,采用荧光定量PCR、MMT、Transwell法检测miR-34a在U251细胞系中表达以及对U251细胞增殖和侵袭能力的影响.依据细胞转染情况,分为Control组(不转染任何基因)、Mock组(转染miRNA-neg序列)和miRNA-34 a mimic组(转染miRNA-34a mimic序列).结果 miRNA-34a在人脑胶质瘤组织中相对表达水平为(0.35±0.07),低于正常人脑组织的(1.00±0.13),差异有统计学意义(P<0.05);转染后,荧光定量PCR结果显示,Control组、Mock组、miRNA-34a mimic组miRNA-34a相对表达水平分别为(1.00±0.08)、(0.98±0.11)和(6.19±0.34),miRNA-34a mimic组与Control、Mock组比较,差异有统计学意义(P<0.05);MMT结果显示,在不同时间点,miRNA-34a mimic组U251细胞增殖抑制率高于Control组、Mock组,差异有统计学意义(P<0.05);Transwell结果显示,Control组、Mock组、miRNA-34a mimic组侵袭细胞数分别为(90.53±5.84)个、(88.21±5.04)个和(27.46±2.76)个,miRNA-34a mimic组与Control、Mock组比较,差异有统计学意义(P<0.05).结论miR-34a在胶质瘤组织中表达下调,上调miR-34a表达可抑制胶质瘤细胞的增殖及侵袭.