RASSF1A基因甲基化与肿瘤的关系

RASSF1A(Ras association domain family 1 Agene) 是RAS相关结构域家族RASSF1基因的转录本A, 它编码一组RAS效应蛋白,它的启动子高甲基化及其基因外失活已在多种人肿瘤细胞株和原发性癌组织中普遍存在,它在多种恶性肿瘤的发生和诱导细胞凋亡的过程中发挥作用。     

RASSF1基因转录本A和C的表达与卵巢癌关系的研究

目的探讨RASSF1基因转录本A和C在多个卵巢癌细胞系和卵巢癌组织中所起的作用。方法应用逆转录聚合酶链反应(RT PCR)和激光捕获显微切割技术检测3个卵巢癌细胞系和80例人原发卵巢上皮性恶性肿瘤组织中RASSF1A和RASSF1CmRNA的表达。结果RASSF1A mRNA在卵巢癌SK OV3细胞中表达缺失;RASSF1A和RASSF1C在人卵巢癌组织中的表达率分别为40.0%(32/80)和91.3%(73/80)。RASSF1AmRNA的表达在浆液性癌、黏液性癌和内膜样癌组织中分别是41.2%(20/48),38.1%(8/21)和36.4%(4/11),P>0.05;临床Ⅰ期和Ⅱ期分别为71.4%和75.0%(10/14,9/12),明显高于临床Ⅲ期和Ⅳ期(26.7%、12/45和14.1%,1/9),P<0.05;高和中分化组分别为58.6%和50.0%(17/29,10/20),明显高于低分化组(16.1%,5/31),P<0.05。结论卵巢癌细胞和人原发卵巢癌组织中存在RASSF1AmRNA表达的缺失,RASSF1A的表达与卵巢癌的临床分期和组织学分级有关,可能作为一种新的抑癌基因在卵巢癌的发生和发展过程中起重要作用,RASSF1AmRNA的缺失提示预后不良。     

Association of RASSF1A hypermethylation with risk of HBV/HCV-induced hepatocellular carcinoma: A meta-analysis

BackgroundResearchers have discovered a large number of DNA methylation patterns in human cancer. These cancer-specific methylation patterns can provide information for the diagnosis, treatment, and prognosis of cancer. Methylation studies can find new biomarkers based on epigenetic analysis and apply these biomarkers to clinical oncology. Many studies on the association between RAASF1A methylation status and susceptibility to hepatitis B virus (HBV)/hepatitis C virus (HCV)-induced hepatocellular carcinoma (HCC) have reached controversial conclusions. Hence, the current review comprehensively assessed the correlation between Ras association domain family 1A (RASSF1A) methylation and the risk of the HCV/HBV-induced HCC.MethodsThe appropriated publications were extracted in EMBASE, PubMed, Web of Science, Cochrane Library, and China National Knowledge Infrastructure databases using STATA 5.0 software. The odds ratios (ORs) with 95 % confidence interval (95 % CI) of RASSF1A methylation were computed.ResultsA total of 1015 HBV/HCV-related HCC samples, 124 non-HBV/HCV-related HCC (NBNC-HCC) samples, and 1225 nontumorous controls were extracted and examined in this research. The frequency of the methylated RASSF1A in the HBV/HCV-related tumor cases displayed a significantly increased OR compared with the overall nontumor samples (OR = 19.372, 95 % CI = 11.060–33.931, P = 0.000). The frequency of the methylated RASSF1A in HBV/HCV-related neoplasm cases displayed a significantly increased OR compared with the non-HBV/HCV-related neoplasm (NBNC-neoplasm) samples (OR = 2.150, 95 % CI = 1.398–3.308, P = 0.000). Compared with normal, chronic hepatitis B or C, cirrhosis, and paracancerous samples, the pooled OR of the RASSF1A promoter methylation in the HBV/HCV-induced HCC samples was 62.785(95 % CI = 35.224–111.909), 25.07 (95 % CI = 13.85–45.36), 6.89 (95 % CI = 3.33–14.264) and 9.02 (95 % CI = 0.91–89.80), respectively. The rate of RASSF1A hypermethylation was robustly correlated with tumor size and vascular invasion, and the pooled OR was 0.346 (95 % CI = 0.210 – 0.569) and 0.081 (95 % CI = 0.022 – 0.303), respectively.ConclusionResults showed robust associations between RASSF1A gene methylation in promoter region and enhanced HBV/HCV-related HCC susceptibility, thereby revealing that RASSF1A methylation status may serve as an important indicator for HCC oncogenesis.     

卵巢癌患者血液中RASSF1A基因甲基化的检测及其意义

目的 探讨循环肿瘤DNA中RASSF1A基因的甲基化及其与卵巢癌的关系。方法 应用甲基化特异性PCR（MSP）方法,对51名正常健康人、51例卵巢癌患者和51例卵巢良性肿瘤患者循环DNARASSF1A基因的甲基化进行了检测。结果 51名正常健康人和51例卵巢良性肿瘤患者循环DNARASSF1A基因甲基化的发生率均为0;51例卵巢癌患者循环肿瘤DNARASSF1A甲基化的发生率为43．1％（22／51,P〈0．05）。RASSF1A甲基化与卵巢癌组织学类型无明显相关性（P〉0.05）。临床Ⅰ期和Ⅱ期循环肿瘤DNARASSF1A基因甲基化的发生率明显低于临床Ⅲ期和Ⅳ期（P〈0．05）;高和中分化组RASSF1A基因甲基化的发生率低于低分化组（P〈0．05）。结论 RASSF1A基因甲基化在卵巢癌的发生和发展过程中起重要作用。卵巢癌患者的循环肿瘤DNA中可以检测到RASSF1A基因的甲基化,与卵巢癌的临床分期和组织学分级有关。循环肿瘤DNA中RASSF1A甲基化的检测有助于卵巢癌的诊断和预后判定。     

p73基因在卵巢上皮性肿瘤中的表达及甲基化研究

目的 探讨卵巢上皮性肿瘤中p73蛋白的表达和基因启动子的甲基化情况,并观察其与临床病理学特征的关系.方法 制备包括68例卵巢癌、37例卵巢交界性肿瘤和21例卵巢良性肿瘤的组织芯片,用免疫组织化学EnVision法检测上述组织中p73蛋白表达情况,用亚硫酸氧盐修饰后测序法检测13例新鲜卵巢癌组织及5例新鲜卵巢交界性肿瘤组织的p73基因启动子甲基化情况.结果 92.6％ (63/68)的卵巢癌表达p73,p73蛋白总体表达率均值为32％(p73表达率指p73阳性细胞数所占的百分比),其中浆液性癌( 26/26)的表达率均值为40％,高于其他组织类型的癌(P=0.006).按照卵巢癌发病模式区分,Ⅱ型卵巢癌p73表达率均值(40％)高于Ⅰ型卵巢癌(24％),P=0.010.卵巢癌中p73的表达与临床分期及组织学分级无相关性(均P＞0.05).卵巢交界性肿瘤组(30/37)和良性肿瘤组(12/21)p73的总体表达率均值分别为16％和15％,该两组肿瘤中浆液性肿瘤表达率均值均高于黏液性肿瘤(P-0.003,P=0.026).卵巢癌组的p73阳性表达率均值明显高于交界性肿瘤组和良性肿瘤组(均P ＜0.05),交界性肿瘤组与良性肿瘤组比较差异无统计学意义(P＞0.05).浆液性肿瘤( 49/53)中,卵巢癌组(26/26) p73阳性表达率均值明显高于交界性肿瘤组(12/14)和良性肿瘤组(11/13;P =0.024和P=0.002),而卵巢交界性肿瘤组和良性肿瘤组比较差异无统计学意义(P=0.428).黏液性肿瘤(15/27)中,卵巢癌组(6/7)p73阳性表达率均值高于良性肿瘤组( 1/8;p=0.032),而卵巢癌组与卵巢交界性肿瘤组(8/12)、交界性肿瘤组与良性肿瘤组比较,差异均无统计学意义(P=0.234和P=0.201).p73启动子的甲基化结果显示,13例卵巢癌有8例发生甲基化,但每例样本甲基化频率有所不同,总体甲基化频率均值为8.0％.5例交界性肿瘤有2例发生甲基化,总体甲基化频率均值为9.0％,两组比较差异无统计学意义(P＞0.05).卵巢癌组p73甲基化额率与组织类型、发病模式、组织学分级及临床分期均无相关性(均P＞0.05).结论 卵巢上皮性肿瘤多数表达p73,卵巢癌p73的表达率均值明显高于交界性肿瘤和良性肿瘤,浆液性肿瘤高于其他组织类型;p73蛋白表达率与p73基因甲基化程度不存在简单线性相关关系.     

髓母细胞瘤与幕上原始神经外胚叶肿瘤中RASSF1A基因的甲基化差异

目的通过研究髓母细胞瘤与幕上原始神经外胚叶肿瘤（SPNET）中RASSF1A基因的甲基化改变,探讨颅内原始神经外胚叶肿瘤（PNET）的不同亚型中该基因的表遗传学差异及其意义。方法收集25例原发髓母细胞瘤,9例原发SPNET,3株髓母细胞瘤细胞系和2株SPNET细胞系。采用甲基化特异性聚合酶链反应（MSP）检测RASSF1A基因启动子区的甲基化状态。应用去甲基化试剂5-aza-2’deoxycytidine处理存在基因表达缺失的细胞系,探讨基因表达与甲基化之间的关系。结果100％（25／25）的原发髓母细胞瘤、6／9的原发SPNET及全部PNET细胞系中均检测到RASSFIA基因的甲基化。相反,该基因甲基化在全部正常组织（包括2例小脑,5例大脑）中均未检测到。并且,RASSF1A在SPNET中的甲基化率明显低于髓母细胞瘤（Fisher精确检验,P=0．014）。在经去甲基化试剂处理的PNET细胞中,该基因表达得以恢复,证明甲基化与该基因沉默相关。结论RASSF1A甲基化是肿瘤特异性的,RASSF1A甲基化与PNET的发生有一定关联,不同亚型的PNET之间RASSF1A基因的不同甲基化状态提示髓母细胞瘤和SPNET是表遗传学上存在差异的两类肿瘤。     

RASSF1A及其在肿瘤发生中的作用

RASSF1A（Ras-assotiation domain family 1 A）基因是一个新型抑癌基因。目前的研究已经在许多肿瘤中发现了这个基因的失活。虽然这个基因的失活可因基因缺失或突变引起，但最常见的原因还是该基因的启动子区甲基化紊乱。这种表形遗传学改变被证实是肿瘤形成的一个早期事件，是肿瘤形成的主要因素之一。RASSF1A有多个结构域，被认为是一种潜在的Ras癌蛋白效应分子，能与活化的Ras结合，调节凋亡及细胞周期信号通路，在细胞的凋亡、增殖、分化及维持细胞的稳定中发挥多种生物学效应，与肿瘤的发生发展密切相关。     

上皮性卵巢癌组织脆性组氨酸三联基因甲基化和3p14的等位基因丢失

目的 探讨肿瘤抑制基因脆性组氨酸三联(FHIT)基因在上皮性卵巢癌(简称卵巢癌)组织中的甲基化状态以及该基因定位的3p14位点的等位基因丢失及其在卵巢癌的发生发展中的作用。方法采用甲基化特异性聚合酶链反应(MSP)方法检测61例卵巢癌组织及10例交界性上皮性卵巢肿瘤(简称交界性卵巢肿瘤)组织FHIT基因启动子CpG岛的甲基化频率,并采用微卫星多态性标志D3S1287检测45例卵巢癌组织3p14位点杂合子丢失(LOH)和纯合子丢失(HD)状态。结果卵巢癌组织中FHIT基因甲基化频率为39．3％(24／61),其中浆液性囊腺癌为45．2％(19／42),黏液性囊腺癌为14．3％(1／7),子宫内膜样癌为33．3％(4／12);交界性卵巢肿瘤组织中FHIT基因甲基化为6／10,其中交界性浆液性囊腺瘤1／3,交界性黏液性囊腺瘤5／7。卵巢癌组织甲基化频率与临床分期、细胞分化程度相关性无统计学意义。交界性卵巢肿瘤与卵巢癌之甲基化频率差异无统计学意义。43．5％(10／23)卵巢癌显示LOH;有信息的浆液性囊腺癌中33．3％(6／18)检测到HD。FHIT基因甲基化与基因丢失之间无明显相关性。结论首次证实卵巢癌FHIT基因启动子有较高的甲基化频率,这可能是FHIT基因沉默的重要原因,在卵巢癌的发生与发展过程中起着重要的作用;同时3p14位点等位基因的丢失可使基因完全失去功能,促进肿瘤的发生。     

肺癌患者RASSF1A启动子甲基化状态及其基因表达水平

目的探讨肺癌RAS相关区域家族1A(RASSF1A)启动子CpG岛甲基化状态和基因表达水平与肺癌发生的关系。方法用甲基化特异性PCR检测RASSF1A启动子CpG岛甲基化状态,实时定量PCR检测RASSF1A mRNA的表达水平。结果在肺癌组织中RASSF1A启动子甲基化频率为53.33%(24/45),在正常肺组织中发生甲基化的频率为13.04%(3/23)(P<0.05)。正常肺组织中RASSF1A mRNA全部表达,肺癌组织中表达缺失率为28.89%(13/45),且表达量低于正常肺组织(P<0.05);不同年龄、性别、肿瘤大小、恶性程度、肿瘤分类中其表达量无显著差异;RASSF1A甲基化与其mRNA表达水平下降密切相关。结论肺癌中RASSF1A基因启动子甲基化频率明显升高,其表达普遍下调或缺失,提示RASSF1A启动子甲基化在肺癌发生、发展中起一定作用。     

人RASSF1A基因的真核表达载体的构建及其表达

目的 通过构建人RASSF1A基因的真核表达载体,为研究其在肿瘤细胞凋亡、细胞周期阻滞、细胞增殖抑制等方面奠定基础.方法 采用RT-PCR从人外周血的单个核细胞RNA中扩增出人RASSF1A基因的全长cDNA,利用DNA重组技术将其插入到真核表达栽体pcDNA3.1(+)中获得重组质粒.利用脂质体将重组质粒转染入人鼻咽癌细胞株CNE-2中,采用RT-PCR.westem-blot检测RASSF1A的瞬时表达.结果 酶切图谱分析及基因测序证明人RASSF1A基因已被完整、正确地插入到pcDNA3.1(+)质粒载体中,RT-PCR及Western-blot结果显示转染细胞的RASSF1A表达水平上调.结论 成功构建了RASSF1A基因的真核表达栽体pcDNA3.1(+)/RASSF1A.     

GSTP1 promoter hypermethylation is an early event in breast carcinogenesis

Promoter hypermethylation in precursor lesions of the breast cancer may be biomarkers of cancer risk and targets for cancer chemoprevention. Pi-class glutathione-S-transferases (GSTP1) is inactivated by promoter hypermethylation in invasive breast cancers. However, little is known about epigenetic silencing of GSTP1 gene by promoter hypermethylation in precursor lesions. To determine the significance of GSTP1 promoter hypermethylation in breast carcinogenesis, methylation status of GSTP1 gene was studied by nested methylation-specific polymerase chain reaction, and GSTP1 expression was studied by immunohistochemistry in invasive ductal carcinoma (IDC), ductal carcinoma in situ (DCIS), usual ductal hyperplasia (UDH), and normal breast tissue. GSTP1 promoter hypermethylation was detected in 4/24 (16.7%) of UDH, 18/49 (36.7%) of DCIS, and 14/36 (38.9%) of IDC. No hypermethylation was detected in normal breast tissues. GSTP1 promoter hypermethylation was found to be progressively elevated during breast carcinogenesis (p < 0.01). GSTP1 promoter hypermethylation was associated with loss of GSTP1 expression (p < 0.01 for UDH, p < 0.001 for DCIS and IDC). Our results suggest that GSTP1 promoter hypermethylation is an early event in breast carcinogenesis and appears to functionally silence GSTP1 expression. GSTP1 promoter hypermethylation in the precursor lesions of breast cancer may be used as a target for cancer chemoprevention.     

肾细胞癌RASSF1A基因启动子区甲基化状况与表达水平研究

目的检测19例肾细胞癌患者癌组织及癌旁组织Ras相关区域家族蛋白1A（RASSFlA）基因启动子区甲基化情况并检测其mRNA表达水平，探索两者之间的联系。方法收集肾细胞癌患者癌组织及相应癌旁组织19份，分别提取其基因组DNA，以甲基化特异性PCR（Methylation special PCR，MSP）法检测RASSFlA基因启动子区甲基化情况。并以QPCR法检测了RASSFlA基因的mRNA表达水平。结果19例中有lO例肾细胞癌患者癌组织存在高甲基化，mRNA表达水平表达降低，二者之间存在显著负相关性（r=-0．8734，P〈0．01）。结论肾细胞癌中RASSFlA基因启动子区存在高甲基化，并抑制该基因的表达。     

定量检测子痫前期孕妇血浆中超甲基化的RASSF1A基因

目的 探讨子痫前期孕妇血浆中超甲基化的Ras相关区域家族1A(ras association domain family 1A,RASSF1A)基因的水平变化及应用价值.方法 选择晚期妊娠子痫前期患者60例为实验组,其中轻度和重度子痫前期各30例;正常晚期孕妇60名为对照组.提取血浆游离DNA,经甲基化敏感的限制性内切酶处理,实时定量检测酶切前、后RASSF1A基因的浓度,同时检测β肌动蛋白(β-actin)基因以确保酶的完全消化.结果 子痫前期孕妇血浆中超甲基化的RASSF1A基因含量为正常妊娠组的3.31倍.轻、重度子痫前期患者浓度有差异,中位数分别为1659.00 copies/mL及2036.50 copies/mL(P<0.05).结论 子痫前期孕妇血浆中的超甲基化RASSF1A基因含量明显升高,且浓度水平与子痫前期的严重程度相关.     

抑癌基因RASSF1A微卫星变异与宫颈癌发生发展的关系

目的 探讨抑癌基因RASSF1A微卫星变异在宫颈癌发生发展中的作用及其与HPV感染的关系.方法 选择RASSF1A基因的两个微卫星多态标记位点,采用PCR技术对宫颈组织进行杂合性丢失与微卫星不稳定性的检测,同时检测宫颈组织中HPV16的感染状况.结果 两位点的LOH发生率在宫颈癌组织临床分期及病理分级之间差异有统计学意义(P＜0.05).双位点的LOH及MSI在宫颈癌有无淋巴结转移间差异有统计学意义(P＜0.05).RASSF1A基因的LOH发生率在HPV16感染阳性组中明显高于阴性组(P＜0.05).结论 RASSF1A基因的改变是宫颈癌发生过程中的较晚期事件,RASSF1A基因的LOH与MSI对于宫颈癌的筛查、早期诊断及判断预后可能具有临床实用价值.RASSF1A基因的LOH与HPV16感染二者共同作用在宫颈癌的发生发展过程中更有意义.     

Analysis of the NSD1 promoter region in patients with a Sotos syndrome phenotype

Sotos syndrome (SoS, OMIM#117550) is an overgrowth disorder characterized by excessive growth—especially in the first years of childhood—distinctive craniofacial features, and various degrees of mental retardation. Haploinsufficiency of the nuclear receptor binding SET domain containing protein 1 (NSD1) gene, due to either intragenic mutations or whole-gene microdeletions, is found in the majority of patients with SoS. However, in approximately 10–40% of patients with a typical SoS phenotype, no abnormalities are detected. In this study, hemizygous hypermethylation or genomic sequence abnormalities of the promoter region of NSD1 were hypothesized to be the underlying cause in patients with a SoS phenotype, but without confirmed NSD1 alterations. In 18 patients, including one patient with a reported hepatocellular carcinoma, the promoter region of NSD1 was analyzed. However, no hypermethylation or sequence abnormalities in the promoter region could be detected. It therefore seems unlikely that such abnormalities of NSD1 are a major culprit in patients with phenotypical SoS. Additional methods are necessary for detection of other genetic or epigenetic causes of SoS.     

High frequency of RASSF1A and RARb2 gene promoter methylation in morphologically normal endometrium adjacent to endometrioid adenocarcinoma

Aims: To identify a DNA methylation signature of endometrioid carcinoma of the endometrium (EEC) in the early stages of endometrial carcinogenesis. Methods and results: Archival biopsy specimens of 39 EECs, 14 cases of atypical hyperplasia (AH), 11 histologically normal endometrial tissues adjacent to EECs and 24 normal control endometrial samples were retrieved. The cases were tested by quantitative methylation‐specific polymerase chain reaction with primers hybridizing in the promoter regions of five genes frequently methylated in human cancer (RASSF1A, RARb2, P16, MGMT and GSTPi). Twenty‐nine of 39 (74%) EECs and 7/14 (50%) AHs were methylated for the RASSF1A gene, whereas 17/39 (44%) EECs and 6/14 (43%) AHs were positive for the methylation of the RARb2 gene. No significant results were obtained for the other genes (P16, MGMT and GSTPi). Interestingly, 4/11 (36%) and 6/11 (55%) histologically normal endometrial tissues adjacent to EEC showed, respectively, RASSF1A and RARb2 gene methylation. Furthermore, these 11 specimens were microsatellite stable and showed similar proliferative, cell cycle and apoptotic mean labelling indices as the normal endometrial control tissues. Conclusions: Promoter region methylation of RASSF1A and RARb2 genes is an early event in endometrial carcinogenesis.     

DNA ploidy and MYC DNA amplification in ovarian carcinomas

There is increasing evidence that DNA ploidy is a prognostic factor in ovarian carcinomas, but it is uncertain whether MYC DNA amplification is an epiphenomenon of DNA nondiploidy or a distinct biological change with an impact on the clinical course of the disease. To clarify these issues we analysed DNA ploidy by flow and image cytometry and MYC copy number by polymerase chain reaction in archival material from ovarian carcinomas with known follow up. The results were compared with proliferative activity (Ki67 index) and p53 and bcl-2 expression. DNA cytometry revealed nondiploidy in 84 of 144 cases (58.3%). Nondiploidy was statistically significantly correlated with histological tumour type, histological grade, Ki67 index >10%, FIGO stage, presence of residual tumour after debulking surgery and adverse postoperative outcome. Furthermore, DNA nondiploidy was associated with p53 accumulation. We found that 84.9% of the p53-positive cases were nondiploid. This points to the paramount importance of wild type p53 for the maintenance of genome integrity in this tumour type. MYC DNA amplification was seen in 33.8% (26/77 cases) of ovarian carcinoma. There was no correlation between MYC DNA amplification and histological tumour type, histological grade, FIGO stage, DNA ploidy, proliferative activity or prognosis. However, when p53 and bcl-2 expression was taken into account, a statistically significant correlation between gene alteration or expression patterns and histological tumour type was revealed. The group of mucinous carcinomas demonstrated both MYC DNA amplification and strong bcl-2 expression in 50% and contained the largest fraction of cases without aberration (37.5%). Endometrioid carcinomas were characterized by strong bcl-2 expression in 85%, whereas serous and undifferentiated carcinomas predominantly exhibited p53 alterations, frequently accompanied by bcl-2 overexpression or MYC DNA amplification. Thus, in interaction with other genes MYC DNA amplification may play a role in the determination of the varying differentiation patterns of ovarian carcinomas.