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。     

Ras相关区域家族1A基因及其与肺癌相关的研究进展

新近在肺癌和乳腺癌的研究中发现的Ras相关区域家族1A(Ras-association domain family 1A,RASSF1A)基因位于染色体3p21.3,是一种新型的肿瘤抑制基因(tumor suppressor gene,TSG).研究表明,RASSF1A主要通过介导细胞凋亡、阻断细胞周期进展等机制发挥抑癌作用,而该基因的表遗传失活与肺癌等多种恶性肿瘤的发生、发展和预后密切相关.同时其高甲基化的启动子可能是一种新的肿瘤标记物,可应用于肿瘤的诊断、治疗及其他众多领域,有着广阔的临床应用前景.     

宫颈癌中RASSF1A基因微卫星的不稳定性

Ras相关区域家族1A(ras association domain family 1A,RASSF1A)基因是新近克隆出来的一种肿瘤抑制基因[1],其在调节细胞周期和细胞凋亡方面具有重要作用。RASSF1A基因失表达见于多种人类肿瘤中。本研究选择RASSF1A基因内的两个微卫星多态标记,对110例宫颈组织进行微卫星不稳定     

Ras相关结构域家族蛋白1A基因与肿瘤

Ras作为一个在人类肿瘤研究中重要的癌基因,已成为目前研究得最为深入的基因之一。研究发现,Ras基因除了具有促进细胞牛长、增殖的作用外还具有一个非常重要的功能——抑制细胞生长、促进细胞凋亡和衰老。2000年,一个与鼠Ras效应蛋白Nore1和Maxp 1高度同源的蛋白编码基因——Ras相关结构域家族蛋白1A(RAS associalion domain family proteinlA,RASSF1A)基因的发现引起了研究者们的广泛关注,对其结卡勾、功能、分布和表达情况的研究发现,     

肺癌基因治疗研究进展

1　抑癌基因　　肿瘤的形成是“癌基因”与“抑癌基因”这对矛盾的平衡被打破的结果 ,如癌基因放大或过度表达 ,抑癌基因失活都会导致癌变发生。抑癌基因有很多如ＴＰ5 3、ＲＢ、Ｐ1 6、Ｂａｘ等 ,其中ＴＰ5 3是最重要的抑癌基因 ,ＴＰ5 3功能的失活 ,引起抑癌活性丧失 ,促进细胞恶性转化。目前认为ＴＰ5 3基因抑制肿瘤除它直接诱导细胞凋亡外 ,还能诱导肿瘤局部产生ＴＮＦα、ＩＬ-6等炎性细胞因子 ,增强瘤细胞对放、化疗的敏感性。晚近还认为它能抑制肿瘤内ＶＥＧＦ表达 ,抑制肿瘤血管生成。ＴＰ5 3基因在大多恶性肿瘤中表现为突变或缺失 …     

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.     

p16、RASSF1A在肝细胞性肝癌患者肿瘤组织及血浆中异常甲基化的检测及临床意义

目的探讨原发性肝细胞性肝癌(HCC)患者肿瘤组织及血浆中p16及RASSF1A启动子区的甲基化状态及其在HCC早期无创诊断中的意义。方法采用甲基化特异性PCR技术检测60例HCC患者肿瘤组织、癌旁组织、血浆及60例正常肝脏患者肝组织及血浆中p16、RASSF1A基因启动子区域的甲基化状态,分析其与肝癌患者临床病理参数之间的关系。结果 60例HCC患者血浆、肿瘤组织及癌旁中p16基因甲基化率分别为68.3%(41/60)、63.3%(38/60)和41.7%(25/60);RASSF1A基因异常甲基化检出率分别为73.3%(44/60)、70.0%(42/60)和36.7%(22/60);60例正常肝脏患者肝组织及血浆p16、RASSF1A未检测到基因启动子区域的甲基化,差异有统计学意义(P=0.000)。HCC患者外周血浆和癌组织中p16、RASSF1A基因的甲基化率与患者年龄、性别、AFP、有无肝炎病毒感染(HBV)、有无肝硬化、Child分级、肿瘤个数、包膜完整与否、有无癌栓、是否复发、病理分级、肿瘤分期无统计学相关性。结论 HCC患者肿瘤组织及血浆DNA中可检测到RASSF1A基因和p16基因的甲基化,外周血p16基因和RASSF1A基因的甲基化检测对肝癌筛查有重要意义,可能成为HCC新的肿瘤分子标记物。     

肾癌的生物学治疗研究进展

随着近年来科技的发展 ,发现了多种抑癌基因、端粒、端粒酶与肾肿瘤的发生、发展有关。免疫分子及抗血管形成在肾肿瘤的治疗方面有着重要的前景。先将肾癌的生物学治疗研究进展综述如下。1　肾癌的抑癌基因研究进展抑癌基因的失活或癌基因的激活与肿瘤的发生、发展关系密切。抑癌基因的点突变、重组、缺失或甲基化所致的功能失活与多种人类恶性肿瘤的发生及发展有关。抑癌基因编码的蛋白质具有多种功能。在肿瘤的发生过程中 ,抑癌基因的失活比原癌基因的激活起着更关键的作用。抑癌基因编码的蛋白质广泛存在于各种细胞中 ,主要有以下功能 :1…     

PIAS3抑癌效应研究进展

肿瘤是一种基因病,涉及到癌基因的激活和/或抑癌基因的失活.在这些基因中,某个或某些基因可能起了关键作用,其通过对下游细胞信号分子或网络的影响,进一步影响细胞的增殖和凋亡过程,造成失控性细胞增殖,最终形成肿瘤.     

肿瘤抑制基因DNA甲基化与卵巢癌的研究进展

卵巢癌是妇科常见的恶性肿瘤,严重威胁着女性的生命和健康。研究发现,DNA异常甲基化,尤其是基因启动子Cp G岛高甲基化,使肿瘤抑制基因RASSF1A、BRCA1等失活,在卵巢癌发生、发展中起重要作用。综述肿瘤抑制基因DNA异常甲基化在卵巢癌中的研究进展,可为卵巢癌发病机制、早期诊断、治疗及判断预后提供新的方法。     

Hypermethylation of RASSF1A in human and rhesus placentas

The pseudomalignant nature of the placenta prompted us to search for tumor suppressor gene hypermethylation, a phenomenon widely reported in cancer, in the human placenta. Nine tumor suppressor genes were studied. Hypermethylation of the Ras association domain family 1 A (RASSF1A) gene was found in human placentas from all three trimesters of pregnancy but was absent in other fetal tissues. Hypermethylation of Rassf1 was similarly observed in placentas from the rhesus monkey but not the mouse. An inverse relationship between RASSF1A promoter methylation and gene expression was demonstrated by bisulfite sequencing of microdissected placental cells and immunohistochemical staining of placental tissue sections using an anti-RASSF1A antibody. Treatment of choriocarcinoma cell lines, JAR and JEG3, by 5-aza-2'-deoxycytidine and trichostatin A led to reduction in RASSF1A methylation but increased expression. These observations extend the analogy between the primate placenta and malignant tumors to the epigenetic level.     

Characterization of mouse embryonic fibroblasts derived from Rassf6 knockout mice shows the implication of Rassf6 in the regulation of NF-κB signaling

RASSF6 is a member of the tumor suppressor Ras association domain family (RASSF) proteins. We have reported using human cancer cell lines that RASSF6 induces apoptosis and cell cycle arrest via p53 and plays tumor suppressive roles. In this study, we generated Rassf6 knockout mice by CRISPR/Cas technology. Contrary to our expectation, Rassf6 knockout mice were apparently healthy. However, Rassf6-null mouse embryonic fibroblasts (MEF) were resistant against ultraviolet (UV)-induced apoptosis/cell cycle arrest and senescence. UV-induced p53-target gene expression was compromised, and DNA repair was delayed in Rassf6-null MEF. More importantly, KRAS active mutant promoted the colony formation of Rassf6-null MEF but not the wild-type MEF. RNA sequencing analysis showed that NF-κB signaling was enhanced in Rassf6-null MEF. Consistently, 7,12-dimethylbenz(a)anthracene (DMBA) induced skin inflammation in Rassf6 knockout mice more remarkably than in the wild-type mice. Hence, Rassf6 deficiency not only compromises p53 function but also enhances NF-κB signaling to lead to oncogenesis.     

BCL‐XL binds and antagonizes RASSF6 tumor suppressor to suppress p53 expression

RASSF6, a member of the tumor suppressor Ras‐association domain family proteins, induces apoptosis in the caspase‐dependent and caspase‐independent manners. RASSF6 interacts with MDM2 and stabilizes p53. BCL‐XL is a prosurvival member of BCL‐2 family proteins. BCL‐XL directly inhibits proapoptotic BAX and BAK. BCL‐XL also traps tBID, a proapoptotic activator BH3‐only protein, and sequesters p53. In addition, BCL‐XL regulates the mitochondrial membrane permeability via voltage‐dependent anion channel. In these manners, BCL‐XL plays an antiapoptotic role. We report the interaction of BCL‐XL with RASSF6. BCL‐XL inhibits the interaction between RASSF6 and MDM2 and suppresses p53 expression. Consequently, BCL‐XL antagonizes RASSF6‐mediated apoptosis. Thus, the inhibition of RASSF6‐mediated apoptosis also underlies the prosurvival role of BCL‐XL.     

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。     

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。     

Promoter hypermethylation and reduced expression of RASSF1A are frequent molecular alterations of endometrial carcinoma.

Alterations in the regulation of the RAS-MAPK pathway are frequent in endometrial carcinoma. RASSF1A is a tumor-suppressor gene that can regulate this pathway negatively. RASSF1A has been found to be inactivated by promoter methylation in some human tumors. The aim of the study was to assess the immunohistochemical expression of RASSF1A in normal endometrium and endometrial carcinoma, and to correlate its expression with K-RAS mutations, presence of microsatellite instability, RASSF1A promoter methylation, and clinicopathological data. RASSF1A immunostaining was evaluated in one tissue microarray constructed from 80 paraffin-embedded samples of normal endometrium, and two tissue microarrays constructed with a total of 157 endometrial carcinomas (one constructed with 95 endometrial carcinomas previously evaluated for K-RAS mutations, and microsatellite instability, and another one containing 62 endometrial carcinomas that were also subjected to RASSF1A promoter methylation analysis). RASSF1A immunostaining was correlated with cell proliferation (Ki67), Cyclin D1 expression and clinicopathological data. Promoter methylation of RASSF1A was assessed by methylation-specific PCR. RASSF1A immunostaining was variable during the menstrual cycle in normal endometrium. RASSF1A expression was significantly reduced in 48% of endometrial carcinomas, particularly in tumors exhibiting microsatellite instability. RASSF1A-promoter methylation was very frequent in endometrial carcinoma (74%), and was frequently associated with reduced expression of RASSF1A. RASSF1A-promoter hypermethylation was common in advanced-stage endometrial carcinoma. The results suggest that reduced expression of RASSF1A may play a role in endometrial carcinogenesis by controlling cell proliferation and apoptosis through the MAPK-signaling pathway.     

Impact of RASSF1A gene methylation on clinico-pathological features of tumor and non-tumor tissue of breast cancer

BackgroundBreast cancer is the most common malignancy in women caused by genetic and epigenetic changes. Promoter DNA methylation in tumor suppressor gene plays a major role in breast cancer. The study determined the association of promoter DNA methylation of RASSF1A gene with clinicopathological features in tumor and non-tumor tissue.Materials and methodsA cross sectional study was conducted in the Department of Pathology, Government Institute of Medical Sciences, Greater Noida and Molecular Pathology Laboratory, Department of Pathology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences. Two sections, one from tumor and the other from non-tumor tissue, were obtained and processed for DNA extraction and bisulphite conversion. Methylation specific PCR was done and results of RASSF1A promoter methylation were statistically correlated with clinicopathological features.ResultsOf the 27 breast cancer tissue, 22 showed invasive ductal carcinoma, one showed invasive lobular carcinoma, another showed ductal carcinoma in situ and three cases showed malignant phyllodes tumor of breast. DNA promoter methylation was found in all the cases. 93% of tumor tissue samples and 67% of the non-tumor tissue samples were found to be aberrantly methylated. Tumor size and histological grade were found to be significantly (p-val <0.05) associated with the RASSF1A gene promoter methylation.ConclusionA significant association of higher tumor size and tumor histological grade with promoter methylation of RASSF1A gene exists suggestive of its being an important determinant of prognostic staging. This critical event in tumorigenesis may be of clinical utility in assessing breast cancer progression.Micro abstractThe study focuses on the RASSF1A gene promoter methylation and its impact on the clinicopathological features in Indian breast cancer patients highlighting the differences from other genetically different population. We found that RASFF1A gene methylation has significant impact on tumor size and tumor grade. The work carries high significance because it addresses the DNA methylation of tumor suppressor gene in relevance of breast cancer. It may also be the first such report on Indian patients with breast cancer.