RASSF1A基因甲基化作为肿瘤生物学标志的临床应用

RAS相关区域家族1A基因（rasassociation domain family 1A, RASSF1A）是新近发现的一个位于人染色体3p21.3上的抑癌基因。RASSF1表达的缺失是人类恶性肿瘤中最常见的一个分子事件，目前至少有37种肿瘤存在该基因启动子的甲基化。RASSF1基因启动子CpG岛的甲基化在许多肿瘤组织和肿瘤患者体液中检测到，而在正常组织和体液中罕见，提示它具有肿瘤标志物的特征；RASSF1与其他一些基因组合的甲基化分析有助于卵巢癌、乳腺癌、膀胱癌、肾癌、肺癌等的早期诊断。其次，RASSF1甲基化可作为恶变危险因素的监测，良性增生性病变RASSF1A甲基化的出现往往提示恶变的危险性增高。第三，应用于预后判断，因为某些恶性肿瘤RASSF1A甲基化与患者预后不良相关联。第四，RASSF1A甲基化提供了顺铂和三苯氧胺治疗是否耐药的一个标志，并可在癌症患者整个治疗过程给予监控。总之，RASSF1A甲基化作为肿瘤生物标志物在肿瘤的诊断及其他众多领域有一定的临床应用前景。     

RASSF1A基因甲基化与妇科肿瘤

ras相关区域家族1A基因(RASSF1A)启动子区域的高甲基化影响了该基因的转录表达,促进了相关肿瘤的发生发展.研究发现,RASSF1A启动子区域高甲基化与子宫颈癌、卵巢癌和子宫内膜癌等的发生密切相关.     

鼻咽癌组织中RASSF1A基因甲基化的研究

目的观察RASSF1A基因在鼻咽癌组织和慢性鼻咽炎的甲基化情况。方法采用甲基化特异性PCR技术检测16例鼻咽低分化未角化癌和10例鼻咽黏膜慢性炎组织中RASSF1A基因的甲基化。结果RASSF1A基因的高甲基化率在鼻咽癌组织中为93．75％（15／16）,在慢性鼻咽炎组织中为0,两组病例的RASSF1A基因高甲基化率差别显著,P〈0．005。结论RASSF1A基因在鼻咽癌组织中呈高甲基化,可能是影响鼻咽癌发生发展的抑癌基因之一。     

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。     

RASSF1A基因在宫颈癌中的甲基化检测及

目的　探讨宫颈癌组织中RASSF1A(Ras association domain family1A)抑癌基因启动子甲基化状态及临床意义以及与高危型HPVs感染的关系。方法　甲基化特异性聚合酶链反应(MSP)方法检测39例宫颈鳞癌及12例正常宫颈组织中RASSF1A基因甲基化状态。聚合酶链反应(PCR)方法检测宫颈癌组织中HPV16、18型的感染状况。结果　39 例宫颈癌组织中有11 例可见异常甲基化(28.2%);12例正常宫颈组织均未见甲基化;宫颈癌组HPV感染率为69.2%;RASSF1A基因甲基化在淋巴结转移组(75.0%)高于淋巴结未转移组(9.1 %),P<0.05。RASSF1A甲基化在患者年龄、肿瘤大小、病理组织学分级、临床分期和HPVs感染组之间差异无统计学意义, P>0.05。结论　RASSF1A基因启动子区5′CpG岛的高甲基化是导致RASSF1A基因失活的重要机制,可能参与宫颈癌的发生过程。     

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.     

RASSF1A 基因在宫颈癌中的甲基化检测及临床意义

 目的 探讨宫颈癌组织中RASSF1A(Ras association domain family 1A)抑癌基因启动子甲基化状态及临床意义以及与高危型HPVs感染的关系. 方法 甲基化特异性聚合酶链反应(MSP)方法检测39例宫颈鳞癌及12例正常宫颈组织中RASSF1A基因甲基化状态.聚合酶链反应(PCR)方法检测宫颈癌组织中HPV16、18型的感染状况. 结果 39例宫颈癌组织中有11例可见异常甲基化(28.2%);12例正常宫颈组织均未见甲基化;宫颈癌组HPV感染率为69.2%;RASSF1A基因甲基化在淋巴结转移组(75.0%)高于淋巴结未转移组(9.1 %),P<0.05.RASSF1A甲基化在患者年龄、肿瘤大小、病理组织学分级、临床分期和HPVs感染组之间差异无统计学意义, P>0.05.结论 RASSF1A基因启动子区5′-CpG岛的高甲基化是导致RASSF1A基因失活的重要机制,可能参与宫颈癌的发生过程.     

RASSF1A基因甲基化在上皮性卵巢肿瘤中的检测及临床意义

卵巢癌是严重威胁女性健康的一种恶性肿瘤,由于缺乏早期诊断方法,70%的患者就诊时已是晚期,5年生存率仅为20%～30%.因此,如何早期诊断卵巢痛已是当前的研究热点.DNA甲基化是肿瘤发生的早期事件,甲基化表型早于肿瘤恶性表型的出现,且具有基因和肿瘤组织异质性[1],这使其成为目前用于肿瘤诊断最有前景的DNA标志.     

RASSF1A基因在肿瘤发生发展中的作用

肿瘤的发生发展与癌基因的激活和抑癌基因的失活密切相关。大量研究发现,抑癌基因的失活与其启动子高甲基化有密切关联。Ras相关区域家族1A（Ras association domain family 1A,RASSF1A）是2000年发现的新型候选肿瘤抑制基因（tumor suppressor gene,TSG）。Ras基因是人类肿瘤研究中1种重要的癌基因,目前已成为研究得最为深入的癌基因之一。研究发现,Ras基因具有促进细胞生长、增殖的作用,而RASSF1A基因可能是Ras激活信号传导通路中1个负向调节基因,对肿瘤的发生、发展、预后等方面具有重要意义。近年来,国内外学者对其在多种肿瘤中的表达情况、抑癌机制、失活原因及临床应用前景等方面进行了广泛研究,现综述如下。     

贲门腺癌中RASSF1A基因的甲基化状态及表达

 目的 研究贲门腺癌（gastric cardiac adenocarcinoma,GCA）中RASSF1A基因的甲基化状态及其蛋白表达情况。 方法 分别应用甲基化特异性PCR（MSP）、RT-PCR及免疫组织化学SP法检测贲门癌组织及相应癌旁组织的RASSF1A甲基化情况和mRNA水平及蛋白表达情况。 结果 92例贲门癌组织中有54例发生了甲基化,甲基化率为58.7%,显著高于癌旁正常组织（P<0.01）。Ⅲ期和Ⅳ期贲门癌患者中RASSF1A基因发生甲基化的比率显著高于Ⅰ期和Ⅱ期患者（P<0.05）。92例贲门癌组织中有43例RASSF1A基因蛋白表达阴性,与相应癌旁正常组织相比有显著性差异（P<0.01）。Ⅲ期和Ⅳ期贲门癌RASSF1A基因蛋白表达显著低于Ⅰ期和Ⅱ期患者（P<0.05）。发生甲基化的贲门癌组织中RASSF1A的mRNA水平的表达显著低于未发生甲基化的贲门癌组织（P<0.01）。 结论 RASSF1A基因启动子区发生甲基化导致的基因沉默可能是贲门腺癌发生的机制之一。     

hSTC-1作为肿瘤标志物的研究

斯钙素(stanniocalcin,STC)是一种首先在硬骨鱼中发现的糖蛋白激素,该激素由鱼类独有的内分泌腺斯坦尼氏小体所分泌。近年来发现人和其它哺乳动物也存在STC,有STC-1和STC-2两种。有研究探讨了hSTC-1作为肿瘤标志物的可行性,本文主要就hSTC-1作为肿瘤标志物的研究作一综述。     

hSTC-1作为肿瘤标志物的研究

斯钙素（stanniocalcin,STC）是一种首先在硬骨鱼中发现的糖蛋白激素,该激素由鱼类独有的内分泌腺斯坦尼氏小体所分泌。近年来发现人和其它哺乳动物也存在STC,有STC-1和STC-2两种。有研究探讨了hSTC-1作为肿瘤标志物的可行性,本文主要就hSTC-1作为肿瘤标志物的研究作一综述。     

RASSF1A基因在胶质瘤组织中甲基化研究及临床意义

目的：探讨胶质瘤组织及脑正常组织中抑癌基因RASSF1A启动子区甲基化程度及与临床特征的关系。方法：采用甲基化特异性聚合酶链反应（MS-PCR）方法检测46例脑胶质瘤（其中星形细胞瘤19例,室管膜瘤16例,胶质母细胞瘤11例）及6例脑正常组织中RASSF1A基因启动子区甲基化状态。并对RASSF1A基因启动子区甲基化发生情况与临床各因素之间的关系进行分析。结果：（1）46例脑胶质瘤组织DNA标本中RASSF1A基因启动子区甲基化发生率为65．2％（30／46）;6例脑正常组织中RASSF1A基因未发生甲基化;RASSF1A在胶质瘤和脑正常组织之间发生甲基化率比较差异有显著性（P=0.017）。在46例脑胶质瘤中RASSF1A有30例发生甲基化,其中低级别组14例（14／26）,高级别组16例（16／20）,两组之间甲基化率比较无明显差异（P〉0．05）。其中星形细胞瘤、室管膜瘤、胶质母细胞瘤中甲基化发生率分别为63．2％（12／19）、68、8％（11／16）、63．6％（7／11）,各组之间甲基化发生率比较均无统计学意义（P=0．211）。（2）RASSFIA基因启动子区甲基化程度与脑胶质瘤病理分型、肿瘤大小之间无显著相关性。结论：RASSF1A在胶质瘤中有甲基化发生,在脑正常组织中未发生甲基化,检测胶质瘤中RASSF1A基因启动子区甲基化情况对临床判断肿瘤发生发展有指导意义。     

DNA甲基化标志在胃肠肿瘤中的临床应用

DNA甲基化是高等真核生物中经常发生的现象,这种表观遗传学改变常发生在基因的启动子区域,并且不改变DNA序列和遗传密码,具有可逆性,在基因转录调控中发挥重要作用.已近知道抑癌基因和一些与正常细胞功能相关基因的转录失活与DNA甲基化有关,在胃肠肿瘤的发生,发展中起重要作用.随着对DNA甲基化的分子机制的进一步认识,以甲基化为基础的标志在临床的应用,尤其是肿瘤的防治,展现了广阔的前景.目前,这一标志及其相关技术在临床的应用涉及到诊断及治疗等方面,诸如患病风险评估、早期诊断、预后判定、复发监测、治疗反应监测和治疗计划的制定以及可作为治疗靶点等.就DNA甲基化肿瘤标志在胃肠肿瘤中的临床应用研究进展作一综述.     

Clinical utility of RASSF1A methylation in human malignancies

The high frequency of RASSF1A methylation has been noted in a vast number of patients in a broad spectrum of malignancies, suggesting that RASSF1A inactivation is associated with cancer pathogenesis. However, whether this recurrent incidence of RASSF1A hypermethylation in human malignancies and its association with more aggressive tumour phenotype is a frequent event across different cancer types has not yet been discussed. In this review, we interrogated existing evidence for association of RASSF1A hypermethylation with clinicopathological characteristics that can indicate more invasive lesions.     

Association of RASSF1A promoter methylation with gastric cancer risk: a meta-analysis

Ras-association domain family 1A (RASSF1A), a candidate tumor suppressor gene, is frequently silenced and inactivated by hypermethylation of its promoter region in several human tumors. However, the association between RASSF1A promoter methylation and gastric cancer risk remains conflicting. The aim of this study was to assess the association of RASSF1A promoter methylation with gastric cancer risk by a comprehensive meta-analysis. Relevant studies were identified by searches of PubMed and Web of Science databases with no restrictions. Combined odds ratio (OR) and 95 % confidence interval (CI) were used to assess the strength of the association between RASSF1A promoter methylation and gastric cancer risk. A chi-square-based Q test and sensitivity analyses were performed to test the between-study heterogeneity and the contributions of single studies to the final results, respectively. Funnel plots were carried out to evaluate publication bias. Overall, a significant association was observed between RASSF1A promoter methylation and gastric cancer risk (OR, 12.67; 95 % CI, 8.12–19.78; p?<?0.001) with no between-study heterogeneity. Subgroup analyses further revealed that gastric cancer risk was increased for individuals carrying the methylated RASSF1A compared with those with unmethylated RASSF1A. In addition, no publication bias was detected in the overall and subgroup analyses. This study identified a strong association between RASSF1A promoter methylation and risk of gastric cancer and highlighted a promising potential for RASSF1A promoter methylation in gastric cancer risk prediction.     

RASSF1A hypermethylation in pretreatment serum DNA of neuroblastoma patients: a prognostic marker

The tumour suppressor gene RASSF1A is known to be frequently silenced by promoter hypermethylation in neuroblastoma tumours. Here we explored the possible prognostic significance of aberrant promoter hypermethylation of RASSF1A in serum DNA samples of patients with neuroblastoma as a surrogate marker for circulating tumour cells. We analysed the methylation status of the RASSF1A gene in matched tumour and pretreatment serum DNA obtained from 68 neuroblastoma patients. Hypermethylation of RASSF1A in tumour samples was found in 64 patients (94%). In contrast, serum methylation of RASSF1A was observed in 17 patients (25%). Serum methylation of RASSF1A was found to be statistically associated with age ⩾12 months at diagnosis (P=0.002), stage 4 (P<0.001) and MYCN amplification (P<0.001). The influence of serum RASSF1A methylation on prognosis was found to be comparable with that of the currently most reliable marker, MYCN amplification on univariate analysis (hazard ratio, 9.2; 95% confidence interval (CI), 2.8–30.1; P<0.001). In multivariate analysis of survival, methylation of RASSF1A in serum had a hazard ratio of 2.4 (95% CI, 0.6–9.2), although this association did not reach statistical significance (P=0.194). These findings show that the methylation status of RASSF1A in the serum of patients with neuroblastoma has the potential to become a prognostic predictor of outcome.     

RASSF1A is not appropriate as an early detection marker or a prognostic marker for non-small cell lung cancer

Aberrant methylation of several tumor suppressor genes often occurs during the pathogenesis of lung cancer. RASSF1A is one of the tumor suppressor genes, and it is frequently inactivated by hypermethylation of its promoter region in a variety of human cancers, including lung cancer. It has recently been suggested that RASSF1A methylation was frequently observed in poorly differentiated tumors, and that it was correlated with adverse survival in lung adenocarcinoma (Tomizawa Y, et al., Clin Cancer Res 2002;8:2362-8). In this study, we investigated the pathogenetic and clinicopathologic significance of RASSF1A methylation for the development and/or progression of non small cell lung cancer (NSCLC). We examined 116 cases of NSCLC for the methylation status of RASSF1A. Methylation-specific analysis demonstrated that 40.5% (47 of 116) of the cases were methylated at the CpG sites in the promoter. Methylation of RASSF1A was associated with cellular differentiation (p = 0.0244) and it was related to survival (p = 0.0276). However, there was no association between RASSF1A methylation and the individual clinicopathologic features: TNM stage (p > 0.1), recurrence (p > 0.1), lymphatic permeation (p > 0.1) and smoking duration time (p > 0.1). Furthermore, we analyzed RASSF1A's probability as a prognostic marker by using stepwise Cox proportional hazard regression testing. As a result, the stage proved to be the most important factor (p = 0.0089), more than any other factors such as age, gender, cell type, methylation status, differentiation, smoking duration time, tumor size and lymph node permeation. There was no other significant factor other than stage and age. These results show that epigenetic inactivation of RASSF1A cannot be a prognostic marker of NSCLC.