宫颈鳞癌组织中RASSF1A基因甲基化状态及其临床意义

背景与目的:Ras相关区域家族1A(ras associated domain family 1A,RASSF1A)基因是一种肿瘤候选抑痛基因,其启动子区高甲基化与多种人类上皮性肿瘤的发生有关.本研究通过检测宫颈鳞癌(cervical squamous cell carcinoma,CSCC)组织中RASSF1A基因启动子区甲基化状态及其蛋白表达情况,旨在分析RASSF1A基因甲基化与基因失活的相关性,并探讨RASSF1A基因甲基化与CSCC发生的关系.方法:分别采用甲基化特异性PCR(methylation-specific PCR,MSP)及免疫组织化学方法检测15例正常宫颈组织和46例CSCC组织中RASSF1A基因的甲基化程度及RASSF1A蛋白的表达情况,并分析RASSF1A基因甲基化与RASSF1A蛋白表达及其与CSCC临床病理特征之间的关系.结果:正常宫颈组织中未见RASSF1A基因甲基化,而CSCC组织中RASSF1A基因甲基化率为43.5%(20/46),两者比较差异具有统计学意义(P＜0.05).CSCC中临床Ⅰ期、Ⅱ期、Ⅲ～Ⅳ期的甲基化阳性率呈逐渐增高趋势(19.0%→58.8%→75.0%,P＜0.05),不同组织学分级、有无淋巴结转移与RASSF1A基因甲基化间未见明显相关性(P＞0.05).RASSF1A基因甲基化与RASSF1A蛋白的表达呈负相关(r=-0.469,P＜0.05).结论:RASSF1A基因启动子区甲基化是导致RASSF1A蛋白低表达的机制之一,可能与CSCC的发生发展有关.     

RASSF1A基因甲基化与非小细胞肺癌预后的相关性研究

背景与目的研究发现在很多肿瘤中均存在RASSF1A基因启动子区域高甲基化状态导致基因表达失活的现象,本研究就RASSF1A基因启动子的甲基化状态与非小细胞肺癌预后的关系进行探讨。方法采用甲基化特异的PCR检测150例非小细胞肺癌和20例肺部良性病变RASSF1A启动子甲基化状态。结果150例非小细胞肺癌中58例发现RASSF1A启动子存在甲基化(58/158,38.7%),20例肺部良性病变中无一例发现RASSF1A启动子甲基化。存在RASSF1A启动子高甲基化的病例预后较未发现RASSF1A甲基化的病例差(P=0.004),Cox回归分析显示RASSF1A启动子的甲基化状态是非小细胞肺癌术后的一个预后相关因素(RR=1.584,95%CI:1.040-2.411,P=0.032)。结论MSP法检测RASSF1A启动子甲基化状态可以作为非小细胞肺癌术后的一个预后评价指标。     

RAS相关家族1A基因在胃癌中的表达和启动子甲基化

目的分析散发性胃癌中RAS相关家族1A基因(RASSF1A基因)的表达、突变和启动子甲基化状况,探讨RASSF1A基因在胃癌发生、发展中的意义.方法采用定量PCR、RT-PCR和SSCP的检测90例胃癌组织和30例相应癌旁正常组织中RASSF1A基因表达水平以及基因突变的情况;采用甲基化特异性PCR (MSP)方法检测RASSF1A基因启动子甲基化情况.结果 90例胃癌中有52例(57.8%)RASSF1A无表达或表达低下.RASSF1A无表达或表达低下和肿瘤细胞的分化(P<0.05)以及分期(P<0.001)相关,但是和肿瘤的浸润深度以及淋巴结转移不相关(P>0.05).90例胃癌中52例启动子发生甲基化(57.8%),其中90.3%(47/52)的RASSF1A无表达或表达低下组织中检测到RASSF1A基因启动子的甲基化,然而癌旁正常组织未发现有RASSF1A基因启动子的甲基化,SSCP没有发现任何突变.结论胃癌中存在较多的启动子异常甲基化造成RASSF1A基因失活,这可能是胃癌发生发展的因素之一.     

非小细胞肺癌患者血清Ras相关区域家族1A基因启动子异常甲基化检测及其临床意义

目的 研究非小细胞肺癌(NSCLC)患者血清Ras相关区域家族1A(RASSF1A)基因启动子区域的甲基化状态及其临床意义.方法 采用甲基化特异性聚合酶链反应(MSP)技术,检测75例NSCLC患者血清RASSF1A基因启动子区域的甲基化状态,并分析其与临床病理参数之间的相关性.结果75例NSCLC患者血清RASSF1A基因启动子区域异常甲基化检出率为30.7%(23/75),而35例肺部良性疾病患者和15例健康志愿者中检出率均为0,差异有统计学意义(P＜0.001).RASSF1A启动子异常甲基化与NSCLC患者的年龄、性别、病理类型无显著相关性,但在晚期及肿瘤分化程度较低的患者中检出率较高(P＜0.05).结论 RASSF1A启动子异常甲基化在NSCLC的发生、发展中起重要作用,有望成为NSCLC辅助诊断和预后判断的分子标记.     

MSP法检测胃癌组织中RASSF1A基因启动子区甲基化改变

目的:探讨抑癌基因RASSF1A启动子区CpG岛甲基化与胃癌及临床病理特征的关系.方法:采用甲基化特异性PCR(methylation-specific PCR,MSP)法检测60例胃癌组织及相应癌旁组织和30例对照组织中RASSF1A基因启动子区甲基化状态.结果:胃癌组织中RASSF1A基因启动子区CpG岛甲基化率为65.0%(39/60),显著高于癌旁组织6.7%(4/60),及对照组0%(0/30)(P＜0.01).胃癌组织中不同年龄、性别、分化程度及淋巴结转移与否的RASSF1A基因甲基化率的差异均无统计学意义.结论:胃癌中RASSF1A基因启动子区的高甲基化提示其与胃癌的发生密切相关,MSP法对RASSF1A基因启动子区甲基化的检测有望成为胃癌早期监测的重要方法.     

RASSF1A基因与乳腺癌相关性的研究进展

目的:总结RASSF1A基因作为新型的肿瘤抑制因子与乳腺癌发生发展相关性的研究现状,探讨其高甲基化在乳腺癌的早期诊断和治疗方面的研究前景和临床价值.方法:应用PubMed数据库检索系统以“RASSF1A、methylation、breast cancer和epigenetics”为关键词.检索2000-01-2012-08关于RASSF1A基因与乳腺癌相关性研究.纳入标准:1)RASSF1A基因甲基化的相关研究;2)RASSF1A基因高甲基化与乳腺癌相关性的研究.根据纳入标准,符合分析的文献35篇.结果:RASSF1A高甲基化可能是乳腺癌发生和发展中一个早期事件.RASSF1A高甲基化水平在乳腺癌临床诊断中具有较高的阳性率(57％～85％);逆转RASSFIA基因启动子CpG岛高甲基化可成为乳腺癌药物治疗的新方向.RASSF1A基因在乳腺癌诊断和治疗等方面正在得到越来越广泛的研究和应用.结论:RASSF1A基因与乳腺癌的发生发展密切相关,可用于乳腺癌的早期诊断及治疗.     

急性髓系白血病RASSF1A基因启动子区异常甲基化临床意义研究

目的 RASSF1A基因异常甲基化可能参与血液肿瘤的发生,并为微小残留疾病(minimal residual de-sease,MRD)监测、分层、预后评估及靶向治疗提供依据.本研究旨在分析RASSF1A基因启动子区异常甲基化在急性髓系白血病(acutemyeloid leukemia,AML)中的临床意义.方法 选取2005-01-01-2013-03-01解放军总医院(113例)以及第一附属医院(39例)住院患者和门诊体检患者,共152例AML患者骨髓标本以及15例健康供者骨髓标本纳入本项研究.提取基因组DNA,并进行DNA硫化修饰;设计重亚硫酸盐测序PCR(bisulfite sequencing PCR,BS-PCR)引物以及甲基化特异性PCR(methylation specific PCR,MS-PCR)引物,进行PCR扩增,进而电泳分析以及DNA序列分析.同时对RASSF1A高甲基化组以及低甲基化组的血液学特点、骨髓原始细胞比例、细胞遗传学异常、基因异常、完全缓解率和总生存期进行统计学分析.结果 MS-PCR分析结果显示,RASSF1A基因在15例健康人中呈完全非甲基化状态,在152例AML患者中有38例出现启动子区高甲基化状态,其甲基化阳性率为25％.4例MS-PCR阳性AML患者经BS-PCR测序分析后,显示RASSF1A甲基化率分别为88.2％、85.5％、78.6％和92.7％,而在4例MS-PCR阴性患者RASSF1A基因启动子区甲基化率分别为10％、11.8％、12.7％和6.8％,4例健康供者RASSF1A基因启动子区甲基化率分别为5.0％、9.1％、8.2％和7.3％.进而通过统计学分析发现携带RASSF1A基因高甲基化的AML患者易合并存在ASXL1基因突变或DNMT3A基因突变.携带RASSF1A基因高甲基化的AML患者,其无进展生存期以及总生存期较短.结论 RASSF1A基因启动子区异常甲基化可能参与AML的发生,同时可能为AML分层诊治以及预后评估提供分子理论依据.     

宫颈癌组织中RASSF1A基因启动子甲基化对其表达水平的影响及临床意义

目的 研究宫颈癌组织中RAS相关区域家族1A基因(RASSF1A)启动子甲基化水平和RASSF1A基因mRNA表达水平,分析其与宫颈癌临床病理参数的关系及临床意义.方法 收集40例宫颈癌组织及相应癌旁组织,采用巢式特异性甲基化方法检测RASSF1A基因启动子甲基化水平,采用实时荧光定量PCR(qRT-PCR)检测宫颈癌和癌旁组织中RASSF1A基因mRNA表达水平.结果 宫颈癌组织中RASSF1A基因mRNA表达水平(0.26±0.05)显著低于癌旁组织(0.28±0.03),差异有统计学意义(t=2.27,P=0.026);宫颈癌组织中RASSF1A基因启动子区的甲基化率(0.71%±0.04%)显著高于癌旁组织(0.66%±0.03%),差异有统计学意义(t=6.78,P=0.000);RASSF1A基因mRNA表达水平与病理分化程度(t=3.31,P=0.002)、国际妇产科联合会(FIGO)分期(t=2.13,P=0.040)、淋巴结转移(t=2.56,P=0.015)、浸润深度(t=2.93,P=0.006)有关;RASSF1A基因启动子区的甲基化水平与病理分化程度(t=2.08,P=0.045)、FIGO分期(t=2.66,P=0.011)、淋巴转移(t=2.22,P=0.033)、浸润深度(t=2.12,P=0.041)有关.结论 宫颈癌组织中RASSF1A基因启动子甲基化和RASSF1A基因mRNA的表达水平与宫颈癌的恶性程度相关,RASSF1A基因甲基化水平有望成为宫颈癌转移风险的重要指标.     

卵巢上皮性恶性肿瘤组织RASSF1A基因启动子区甲基化的研究

目的 探讨RASSF1A基因启动子区异常甲基化与卵巢上皮性恶性肿瘤发生、发展的关系。方法 应用甲基化特异性PCR方法,检测80例卵巢上皮性恶性肿瘤组织RASSF1A基因启动子区异常甲基化。结果 80例卵巢上皮性恶性肿瘤组织中,RASSF1A基因启动子区甲基化的发生率为52．5％,而相应痛旁正常组织中,RASSF1A基因启动子区均未发生甲基化（P〈0．05）。浆液性癌、黏液性癌和内膜样癌中,RASSF1A基因启动子区甲基化的发生率分别为54．2％、52．4％和45．5％,差异尤统计学意义。临床Ⅰ期、Ⅱ期卵巢上皮性恶性肿瘤RASSF1A基因启动子区甲基化的发生率分别为21．4％和16．7％,明显低于临床Ⅲ期（66．7％）和Ⅳ期（77．8％）。高分化组和中分化组RASSFlA基因启动子区甲基化的发牛率分别为34．5％和35．0％,均低于低分化组（80．6％）。结论 卵巢上皮性恶性肿瘤组织中存在RASSF1A基因启动子区的异常甲基化,甲基化与卵巢上皮性恶性肿瘤的临床分期和组织学分级有关。     

MSP法检测胃癌组织中RASSF1A基因启动子区甲基化改变

目的：探讨抑癌基因RASSF1A启动子区CpG岛甲基化与胃癌及临床病理特征的关系。方法：采用甲基化特异性PCR（methylation—specific PCR,MSP）法检测60例胃癌组织及相应癌旁组织和30例对照组织中RASSF1A基因启动子区甲基化状态。结果：胃癌组织中RASSF1A基因启动子区CpG岛甲基化率为65．0％（39／60）,艋著高于癌旁组织6．7％（4／60）,及对照组0％（0／30）（P〈0．01）。胃癌组织中不同年龄、性别、分化程度及淋巴结转移与否的RASSF1A基因甲基化率的差异均无统计学意义。结论：胃癌中RASSF1A基因启动子区的高甲基化提示其与胃癌的发生密切相关,MSP法对RASSF1A基因启动子区甲基化的检测有望成为胃癌早期监测的重要方法。     

The RASSF gene family members RASSF5, RASSF6 and RASSF7 show frequent DNA methylation in neuroblastoma

ABSTRACT: BACKGROUND: Hypermethylation of promotor CpG islands is a common mechanism that inactivates tumor suppressor genes in cancer. Genes belonging to the RASSF gene family have frequently been reported as epigenetically silenced by promotor methylation in human cancers. Two members of this gene family, RASSF1A and RASSF5A have been reported as methylated in neuroblastoma. Data from our previously performed genome-wide DNA methylation array analysis indicated that other members of the RASSF gene family are targeted by DNA methylation in neuroblastoma. RESULTS: In the current study, we found that several of the RASSF family genes (RASSF2, RASSF4, RASSF5, RASSF6, RASSF7, and RASSF10) to various degrees were methylated in neuroblastoma cell lines and primary tumors. In addition, several of the RASSF family genes showed low or absent mRNA expression in neuroblastoma cell lines. RASSF5 and RASSF6 were to various degrees methylated in a large portion of neuroblastoma tumors and RASSF7 was heavily methylated in most tumors. Further, CpG methylation sites in the CpG islands of some RASSF family members could be used to significantly discriminate between biological subgroups of neuroblastoma tumors. For example, RASSF5 methylation highly correlated to MYCN amplification and INRG stage M. Furthermore, high methylation of RASSF6 was correlated to unfavorable outcome, 1p deletion and MYCN amplification in our tumor material. In conclusion This study shows that several genes belonging to the RASSF gene family are methylated in neuroblastoma. The genes RASSF5, RASSF6 and RASSF7 stand out as the most promising candidate genes for further investigations in neuroblastoma.     

RASSF1A基因与乳腺癌的研究进展

RASSF1是新发现的一种定位于染色体3p的肿瘤抑制基因。该基因存在多种不同的转录本,而RASSF1A是最重要最常见的转录本。它在多种实体肿瘤中如乳腺癌表达缺失,其主要原因是启动子甲基化。启动子甲基化作为肿瘤标记物在乳腺癌的诊断、治疗等方面有着广泛的研究前景和临床价值。     

RASSF1A基因与乳腺癌的研究进展

RASSF1是新发现的一种定位于染色体3p的肿瘤抑制基因。该基因存在多种不同的转录本,而RASSF1A是最重要最常见的转录本。它在多种实体肿瘤中如乳腺癌表达缺失,其主要原因是启动子甲基化。启动子甲基化作为肿瘤标记物在乳腺癌的诊断、治疗等方面有着广泛的研究前景和临床价值。     

Frequent hypermethylation of promoter region of RASSF1A in tumor tissues and voided urine of urinary bladder cancer patients

High frequency loss of 3p21.3 region where RASSF1A located was demonstrated in several tumors. We aimed to investigate the methylation status of RASSF1A and the frequency of LOH in 3p21.3 region in bladder cancer. Three bladder cancer cell lines, 40 cases of bladder TCC and 14 cases of paired voided urine samples were subjected to methylation analysis. By methylation specific PCR, complete methylation of promoter region of RASSF1A gene were detected in cell lines T24 and UMUC3. Demethylation treatment re-expressed RASSF1A in these 2 cell lines. Methylation of RASSF1A was also detected in 47.5% (19/40) of the TCC cases but not in 6 carcinoma in situ (CIS) or 6 normal urothelium samples. For LOH study, loss of 3p21.3 region was detected in 57.9% (11/19) of our cases. Interestingly, methylation of RASSF1A was found in 72.7% (8/11) of the cases with LOH but only in 12.5% (1/8) of the cases without LOH. Methylation of RASSF1A was detected in 50% (7/14) of voided urine samples, but not in normal control. It showed a higher sensitivity than conventional urine cytology in detecting cancer cells, especially for low grade cases. In conclusion, our results demonstrated a high frequency of RASSF1A methylation with frequent LOH in 3p21.3 region in bladder cancer. It suggested that it may be a potential tumor suppressor gene in this chromosomal region and can be silenced by promoter hypermethylation. Detection of aberrant gene methylation in routine voided urine was feasible and may provide a non-invasive and sensitive approach for cancer detection.     

Epigenetic inactivation of RASSF1A in lung and breast cancers and malignant phenotype suppression

BACKGROUND: The recently identified RASSF1 locus is located within a 120-kilobase region of chromosome 3p21.3 that frequently undergoes allele loss in lung and breast cancers. We explored the hypothesis that RASSF1 encodes a tumor suppressor gene for lung and breast cancers. METHODS: We assessed expression of two RASSF1 gene products, RASSF1A and RASSF1C, and the methylation status of their respective promoters in 27 non-small-cell lung cancer (NSCLC) cell lines, in 107 resected NSCLCs, in 47 small-cell lung cancer (SCLC) cell lines, in 22 breast cancer cell lines, in 39 resected breast cancers, in 104 nonmalignant lung samples, and in three breast and lung epithelial cultures. We also transfected a lung cancer cell line that lacks RASSF1A expression with vectors containing RASSF1A complementary DNA to determine whether exogenous expression of RASSF1A would affect in vitro growth and in vivo tumorigenicity of this cell line. All statistical tests were two-sided. RESULTS: RASSF1A messenger RNA was expressed in nonmalignant epithelial cultures but not in 100% of the SCLC, in 65% of the NSCLC, or in 60% of the breast cancer lines. By contrast, RASSF1C was expressed in all nonmalignant cell cultures and in nearly all cancer cell lines. RASSF1A promoter hypermethylation was detected in 100% of SCLC, in 63% of NSCLC, in 64% of breast cancer lines, in 30% of primary NSCLCs, and in 49% of primary breast tumors but in none of the nonmalignant lung tissues. RASSF1A promoter hypermethylation in resected NSCLCs was associated with impaired patient survival (P =.046). Exogenous expression of RASSF1A in a cell line lacking expression decreased in vitro colony formation and in vivo tumorigenicity. CONCLUSION: RASSF1A is a potential tumor suppressor gene that undergoes epigenetic inactivation in lung and breast cancers through hypermethylation of its promoter region.     

Detection of RASSF1A aberrant promoter hypermethylation in sputum from chronic smokers and ductal carcinoma in situ from breast cancer patients

The newly identified 3p21.3 tumour suppressor gene RASSF1A is methylated in the majority of primary lung tumours, lung tumour cell lines and in a variable percentage of breast tumours. To determine the extent of RASSF1A promoter hypermethylation in early lung tumorigenesis, we analysed sputum samples from lung cancer patients and from current and former smokers using a sensitive methylation-specific PCR (MSP) technique. We also analysed RASSF1A promoter region hypermethylation in trios of normal breast/invasive ductal breast carcinoma/ductal carcinoma in situ (DCIS) from breast cancer patients and DCIS without invasive cancer. We found that 50% of small cell lung cancer (SCLC) and 21% of non-small cell lung cancer (NSCLC) patients had RASSF1A methylation, while one of two former smokers and four of 13 current smokers demonstrated RASSF1A methylation in sputum. Furthermore, two of the four current smokers and one former smoker showing RASSF1A methylation in their sputum developed cancer within 12-14 months of bronchoscopy. In our breast cancer trios, RASSF1A promoter hypermethylation was detected in 65% of invasive cancers, in 42% of corresponding DCIS but in none of the normal breast samples. In addition, we found that three out of 10 DCIS without invasive breast cancer also underwent RASSF1A promoter hypermethylation. Our findings suggest that RASSF1A promoter region hypermethylation may be a useful molecular marker for early detection of lung cancer. Furthermore, since RASSF1A promoter hypermethylation was detected in ductal carcinoma in situ, inactivation of RASSF1A may be an early event in breast tumorigenesis.     

Identification of epigenetic aberrant promoter methylation of RASSF1A in serum DNA and its clinicopathological significance in lung cancer

RASSF1A is a novel putative tumor suppressor gene located in 3p21.3 region. The most common inactivation mechanism of RASSF1A is promoter hypermethylation, which is observed in multiple solid tumors including lung cancer. In the present study, we identified the methylation status of RASSF1A in lung cancer sera using methylation-specific PCR and analyzed its clinicopathological significance. Hypermethylation of RASSF1A was detected in 27 of 80 (33.8%) cancer patients but no benign pulmonary disease patients or healthy donors (P<0.001). RASSF1A hypermethylation was preferentially observed in small cell lung cancer (P=0.042), while no statistical difference was found among methylation frequencies of different subtypes of non-small cell lung cancer. RASSF1A methylation status was associated with differentiation (P=0.009) and stage (P=0.013), but not with gender, age or treatment. These findings suggest that serum RASSF1A hypermethylation is a promising molecular biomarker for lung cancer diagnosis.     

宫颈癌细胞系RASSFIA基因启动子及第1外显子区甲基化状态的研究

背景与目的：抑癌基因Ras相关区域家族1A (Ras association domain family 1A,RASSF1A)启动子及第1外显子区CG位点高甲基化导致该基因沉默与多种恶性肿瘤的发生发展相关。本研究旨在探讨宫颈癌细胞系RASSFIA基因启动子及第1外显子区甲基化状态以及甲基化转移酶抑制剂5-氮杂-2’-脱氧胞苷(5-Aza-2’deoxycytidine,5-Aza-dc)作用对RASSFIA基因表达的影响。方法：采用5 μmol/L(低浓度)和10 μmol/L(高浓度)的5-Aza-dc作用于HeLa、Caski、HT-3以及C-33A等4种宫颈癌细胞系,分别采用甲基化特异PCR (methylation-specific PCR,MSP)和亚硫酸盐基因组测序法(bisulfite genome sequencing,BGS)检测5-Aza-dc处理前后RASSF1A基因启动子及第1外显子区甲基化状态,RT-PCR检测干预前后RASSF1A基因mRNA的转录表达。结果：HeLa和Caski两种HPV阳性细胞系RASSF1A基因启动子及第1外显子区均呈低甲基化状态,mRNA表达阳性。低浓度和高浓度5-Aza-dc作用后,mRNA表达未见明显改变(F_HeLa=3.003,P=0.125;F_Caski=0.045,P=0.956)。HT-3和C-33A两种HPV阴性宫颈癌细胞系RASSF1A基因启动子及第1外显子区则表现为高度甲基化状态,mRNA表达受到抑制。低浓度和高浓度5-Aza-dc作用后,HT-3和C-33A细胞系RASSF1A基因启动子及第1外显子区CG位点甲基化程度降低,检测到其mRNA表达,高浓度5-Aza-dc作用组表达水平明显高于低浓度组和细胞对照组(F_HT-3=18.002,P=0.03;F_C-33A=17.179,P=0.03),LSD-t检验显示差异有统计学意义(P<0.05)。结论：HPV阳性和HPV阴性宫颈癌细胞系中RASSFIA基因启动子及第1外显子区甲基化状态不同;RASSF1A基因启动子及第1外显子区的高甲基化可抑制该基因表达;5-Aza-dc处理可使RASSF1A基因启动子及第1外显子区去甲基化,重新激活基因的表达,这种作用在一定范围内有剂量依赖性。