胃和结直肠腺癌患者血清RASSF1A基因启动子异常甲基化检测及其临床意义

目的 研究胃和结直肠腺癌患者血清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47例胃腺癌患者、45例结直肠腺癌患者、60例胃肠道良性病变患者及30例健康志愿者血清RASSF1A基因启动子区域的甲基化状态,并同时检测25例进行手术的胃腺癌、结直肠腺癌患者的肿瘤...     

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.     

Colorectal cancer and RASSF family—A special emphasis on RASSF1A

The RAS‐association domain family, commonly referred to as RASSF, is a family of 10 members (RASSF1‐10) implicated in a variety of key biological processes, including cell cycle regulation, apoptosis and microtubule stability. Furthermore, RASSFs have been implicated in tumorigenesis and several family members are now thought to be tumor suppressors. As opposed to the KRAS oncogene, for which mutational activation is frequent in colorectal cancer (CRC), RASSFs are found to be silenced mainly by aberrant promoter methylation. In particular, RASSF1A, RASSF2 and RASSF5 methylation has been associated with CRC development, though the mechanisms of action remain poorly understood. This review focus on the current knowledge of RASSF inactivation in CRC, particularly RASSF1A, and on the implications RASSFs may have as potential biomarkers and for the development of new targeted therapies for CRC.     

Differential involvement of RASSF2 hypermethylation in breast cancer subtypes and their prognosis

Breast cancer is a heterogeneous disease that can be subdivided into clinical, histopathological and molecular subtypes (luminal A-like, luminal B-like/HER2-negative, luminal B-like/HER2-positive, HER2-positive, and triple-negative). The study of new molecular factors is essential to obtain further insights into the mechanisms involved in the tumorigenesis of each tumor subtype. RASSF2 is a gene that is hypermethylated in breast cancer and whose clinical value has not been previously studied. The hypermethylation of RASSF1 and RASSF2 genes was analyzed in 198 breast tumors of different subtypes. The effect of the demethylating agent 5-aza-2′-deoxycytidine in the re-expression of these genes was examined in triple-negative (BT-549), HER2 (SK-BR-3), and luminal cells (T-47D). Different patterns of RASSF2 expression for distinct tumor subtypes were detected by immunohistochemistry. RASSF2 hypermethylation was much more frequent in luminal subtypes than in non-luminal tumors (p = 0.001). The re-expression of this gene by lentiviral transduction contributed to the differential cell proliferation and response to antineoplastic drugs observed in luminal compared with triple-negative cell lines. RASSF2 hypermethylation is associated with better prognosis in multivariate statistical analysis (P = 0.039). In conclusion, RASSF2 gene is differently methylated in luminal and non-luminal tumors and is a promising suppressor gene with clinical involvement in breast cancer.     

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。     

CpG hypermethylation of promoter region and inactivation of E-cadherin gene in human bladder cancer

Several studies have shown that E-cadherin expression is lost during malignant transformation. We hypothesized that CpG methylation in the promoter region may inactivate the expression of the E-cadherin gene in human bladder cancer. Normal and bladder cancer samples from 51 patients were compared in terms of E-cadherin gene expression and methylation status by immunohistochemistry, methylation-specific polymerase chain reaction (MSP), and bisulfite genome-sequencing techniques. Ten different CpG sites (nt 863, 865, 873, 879, 887, 892, 901, 918, 920, and 940) in the promoter region were studied. Thirty-five of 51 (69%) bladder cancer samples lacked E-cadherin expression, whereas only six of 51 (12%) normal bladder samples lacked E-cadherin immunoreactivity. MSP analysis of bladder cancer samples suggested that 43 of 51 (84%) showed methylation of the promoter region, whereas only 12 of 51 (24%) normal bladder samples showed hypermethylation. Sodium bisulfite genome-sequencing analysis revealed that of 10 CpG sites, two sites (nt 892 and nt 940) showed 100% methylation in all the cancer samples analyzed. Other CpG sites were partially methylated (47-91%). Normal tissue showed only 12% methylation (range, 1-33%) on various CpG sites. Also supporting these data, E-cadherin-negative bladder cancer cell lines restored expression of the E-cadherin gene after treatment with the demethylating agent 5-aza-2'-deoxycytidine. The present study showed that CpG hypermethylation was an important mechanism of E-cadherin gene inactivation in bladder cancer and also that specific CpG sites consistently presented higher methylation levels than others. These findings may provide a better strategy for the diagnosis and management of bladder cancer.     

膀胱肿瘤组织及尿液标本中TWIST1基因的甲基化水平研究

背景与目的：众多遗传学及表观遗传性的改变引发癌基因的激活剂抑癌基因的失活是膀胱肿瘤发生、发展的重要原因,本研究旨在揭示膀胱肿瘤患者肿瘤组织及尿液标本TWIST1基因的甲基化模式。方法：78例经病理确诊的膀胱肿瘤标本、癌旁正常组织及配对75例尿液标本组成实验组,75例年龄及性别比例匹配的非肿瘤个体组成对照组。从肿瘤、癌旁及尿液标本提取DNA,甲基化特异性聚合酶链反应(methylationspecificpolymerase chain reaction,MSP)检测肿瘤组织、癌旁组织及尿液标本中TWIST1基因的甲基化水平,检测结果与尿细胞学检测结果进行对比,比较两种检测方法的灵敏度及特异度。结果：甲基化检测结果显示,88.5%的肿瘤标本及84.0%的尿液标本出现TWIST1基因的甲基化,11.5%的癌旁正常组织及5.3%的对照尿液标本出现甲基化。尿细胞学检测结果显示,49.3%的肿瘤患者尿液标本检测出瘤细胞,17.3%的对照者被诊断为肿瘤或疑似肿瘤。尿液标本甲基化检测灵敏度及特异度显著高于尿细胞学检测方法。针对低级别肿瘤,TWIST1基因甲基化检测灵敏度为66.7%,高于尿细胞学检测(33.3%)。结论：TWIST1基因甲基化水平检测可作为一种简单、非侵入、敏感及特异的方法应用于早期膀胱肿瘤诊断筛查。     

RASSF1A在胃癌中的甲基化检测及表达

目的:探讨RASSF1A基因在胃癌及癌前病变组织中的表达及与启动子区甲基化的关系.方法: RT-PCR方法检测40例胃癌、20例中-重度慢性萎缩性胃炎伴肠上皮化生和不典型增生组织及20例癌旁正常组织RASSF1A mRNA表达,甲基化特异性PCR方法检测RASSF1A启动子区CpG岛甲基化状态;Western blot方法检测RASSF1A蛋白表达.结果: RASSF1AmRNA和蛋白表达水平在胃腺癌组织中明显低于中-重度慢性萎缩性胃炎伴肠上皮化生和不典型增生组及癌旁正常组织;RASSF1A在胃癌组织、中-重度慢性萎缩性胃炎伴肠上皮化生和不典型增生组织和正常组织中的甲基化频率分别为80%、25%和5%, 差异有显著性 (P<0.01);在胃癌组织中,RASSF1A mRNA阳性表达组甲基化明显低于表达缺失组.结论: 胃癌组织RASSF1A mRNA和蛋白表达缺失或低下与其启动子甲基化程度增高有关,启动子甲基化参与了胃癌的发生发展.     

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。     

抑癌基因RASSF1A mRNA在胃癌中的表达及临床意义

目的:检测抑癌基因RASSF1A mRNA在胃癌中的表达情况,探讨RASSF1A在胃癌发生发展中的作用及临床意义。方法:采用实时荧光定量逆转录聚合酶链反应(RT-PCR)分别检测40例胃癌及40例配对的癌旁组织(距癌2 cm)和40例配对远离胃癌的手术切缘正常组织(距癌5cm以上)RASSF1A mRNA的表达水平。结果:RASSF1A mRNA在胃癌中表达的阳性率(35%)显著低于癌旁组织(87.5%)和正常组织(100%)(P均<0.05),癌旁组织明显低于正常组织(P<0.05),且早期胃癌RASSF1A mRNA表达明显高于进展期胃癌(P<0.05)。结论:在原发性胃癌组织中,RASSF1A mRNA表达明显缺失或低下,且与胃癌临床分期显著相关。     

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。     

Frequent occurrence of RASSF1A promoter hypermethylation and merkel cell polyomavirus in merkel cell carcinoma

Merkel cell carcinoma (MCC) is one of the most aggressive cancers of the skin. It has recently been reported that integration of a Merkel cell polyomavirus (MCPyV) in receptor tyrosine phosphates type G (PTPRG) gene occurs in MCC, and that viral infections are associated with epigenetic silencing of tumor suppressor genes (TSG) in cancer. To examine whether a correlation between TSG inactivation and viral infection can be found in MCC, we investigated the promoter hypermethylation of RASSF1A, TP73, PTPRG, FHIT, and CDKN2A and the presence of MCPyV and SV40 in 98 MCC by PCR. Hypermethylation of RASSF1A was frequently found in 42 of 83 (51%) of MCC. Methylation of CDKN2A was present in 9 of 41 (22%) of MCC. Hypermethylation of TP73 (0%), PTPRG (4%), and FHIT (0%) was infrequent in MCC. Interestingly, MCPyV was found in 90 of 98 (92%) MCC, however, no SV40 signal was detected. No correlation between TSG hypermethylation and viral infection was found. Our results show frequent hypermethylation of RASSF1A and the presence of MCPyV in primary MCC, and that these events may contribute to the pathogenesis of MCC. © 2009 Wiley‐Liss, Inc.     

抑癌基因RASSF1A mRNA在胃癌中的表达及临床意义

目的：检测抑癌基因RASSF1A mRNA在胃癌中的表达情况,探讨RASSF1A在胃癌发生发展中的作用及临床意义。方法：采用实时荧光定量逆转录聚合酶链反应（RT-PCR）分别检测40例胃癌及40例配对的癌旁组织（距癌2 cm）和40例配对远离胃癌的手术切缘正常组织（距癌5cm以上）RASSF1A mRNA的表达水平。结果：RASSF1A mRNA在胃癌中表达的阳性率（35%）显著低于癌旁组织（87.5%）和正常组织（100%）（P均〈0.05）,癌旁组织明显低于正常组织（P〈0.05）,且早期胃癌RASSF1A mRNA表达明显高于进展期胃癌（P〈0.05）。结论：在原发性胃癌组织中,RASSF1A mRNA表达明显缺失或低下,且与胃癌临床分期显著相关。     

食管癌组织与外周血RASSF 1A甲基化的检测及其临床意义

目的:通过对食管癌组织及同一患者对应的术前外周血中RASSF1A基因甲基化的检测,加深食管癌变分子机制的了解并为食管癌早期诊断和高危人群预警提供候选指标.方法:采用甲基化特异性PCR方法,分别检测来自食管癌高发区的30例食管癌患者血浆、肿瘤组织及癌旁正常组织中RASSF1A基因启动子甲基化状况.结果:食管癌组织RASSF1A甲基化阳性率为40%(12/30),而这12例癌组织甲基化阳性的患者其外周血甲基化阳性共7例,癌组织和外周血RASSF1A甲基化阳性一致率为58%(7/12),18例癌组织甲基化阴性的患者其外周血也均为阴性,阴性一致率为100%(18/18).癌旁正常食管组织甲基化率为13%(4/30),明显低于癌组织(40%,12/30),P<0.05.7例外周血甲基化阳性的患者中,淋巴结转移阳性5例(55%,5/9),阴性2例(10%,2/21),两者差异有统计学意义,P<0.05.低分化鳞癌的RASSF1A甲基化阳性率(83%,5/6)明显高于中分化鳞癌(24%,5/21),P<0.05.结论:外周血RASSF1A甲基化可以反映同一个体食管鳞癌组织中RASSF1A基因甲基化的状态,可能是高危人群筛查重要候选分子标志之一.     

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。     

Frequent hypermethylation of MST1 and MST2 in soft tissue sarcoma

The RASSF1A tumor suppressor is involved in regulation of apoptosis and cell cycle progression. RASSF1A is localized to microtubules and binds the apoptotic kinases MST1 and MST2. It has been shown that this interaction is mediated by the Sav-RASSF-Hpo domain, which is an interaction domain characterized for the Drosophila proteins Sav (human WW45), Hpo (human MST1 and MST2) and Warts/LATS (large tumor suppressor). Previously, we have reported that RASSF1A hypermethylation occurs frequently in soft tissue sarcoma and is associated with an unfavorable prognosis for cancer patients. In our study, we performed methylation analysis of the CpG island promoter of MST1, MST2, WW45, LATS1 and LATS2 in soft tissue sarcomas by methylation-specific PCR. No or a very low methylation frequency was detected for WW45, LATS1 and LATS2 (<7%). In 19 out of 52 (37%) sarcomas, a methylated promoter of MST1 was detected and 12 out of 60 (20%) samples showed methylation of the MST2 promoter. Methylation status of MST1 was confirmed by bisulfite sequencing. In tumors harboring a methylated promoter of MST1, a reduction of MST1 expression was observed by RT-PCR. In leiomyosarcomas, MST1 and MST2 or RASSF1A methylation were mutually exclusive (P = 0.007 and P = 0.025, respectively). Surprisingly, a significantly increased risk for tumor-related death was found for patients with an unmethylated MST1 promoter (P = 0.036). In summary, our results suggest that alteration of the Sav-RASSF1-Hpo tumor suppressor pathway may occur through hypermethylation of the CpG island promoter of MST1, MST2 and/or RASSF1A in human sarcomas.     

新型肺癌候选抑癌基因RASSF1A研究进展

Ras相关区域家族1A(RASSF1A)是最近从3p1.3上发现的新型候选抑癌基因,在肺癌、乳腺癌和结肠癌等十几种恶性肿瘤中均出现高频率表达失活和异常高甲基化.将该基因转染入肺癌、肾癌等肿瘤细胞株中均可显著抑制癌细胞生长,逆转其恶性表型,提示该基因的失活可能在肺癌等多种肿瘤的发生发展中发挥重要作用.     

Correlation between hypermethylation of the RASSF2A promoter and K-ras/BRAF mutations in microsatellite-stable colorectal cancers

Recently, RASSF2A was identified as a potential tumor suppressor epigenetically inactivated in human cancers. Here, we evaluated the methylation status of RASSF2A in colorectal cancer (CRC) and analyzed its correlation with K-ras/BRAF mutations, microsatellite instability status and other clinicopathological features. Using methylation-specific PCR and bisulfite sequencing, we analyzed the methylation status in primary CRC, adenomas and corresponding normal tissues and then compared it with the presence of K-ras and BRAF mutations. We also examined the expression and methylation status of RASSF2A in CRC cell lines. We found that aberrant methylation of RASSF2A promoter regions is associated with gene silencing in CRC cell lines. In primary CRC, the frequency of RASSF2A methylation was 72.6%, and it was found in 16 of 16 (100%) adenomas. In addition, there was a positive correlation between K-ras/BRAF mutations and RASSF2A methylation in primary CRC. Furthermore, a significant positive correlation between K-ras/BRAF mutations and RASSF2A methylation was also observed in microsatellite-stable (p = 0.033) and distal CRC (p = 0.025). These results show that RASSF2A methylation is a frequent event in colorectal tumorigenesis and positively correlates with K-ras/BRAF mutation in microsatellite-stable or distal CRC.     

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。     

Hypermethylation of multiple genes in tumor tissues and voided urine in urinary bladder cancer patients.

PURPOSE: We aimed to investigate the methylation pattern in bladder cancer and assess the diagnostic potential of such epigenetic changes in urine. EXPERIMENTAL DESIGN: The methylation status of 7 genes (RARbeta, DAPK, E-cadherin, p16, p15, GSTP1, and MGMT) in 98 cases of bladder transitional cell carcinoma and 4 cases of carcinoma in situ was analyzed by methylation-specific PCR. Twenty-two cases had paired voided urine samples for analysis. RESULTS: In transitional cell carcinoma tumor tissues, aberrant methylation was frequently detected in RARbeta (87.8%), DAPK (58.2%), E-cadherin (63.3%), and p16 (26.5%), whereas methylation of p15 (13.3%), GSTP1 (5.1%), and MGMT (5.1%) is not common. No association between methylation status and grading or muscle invasiveness was demonstrated. In 22 paired voided urine samples of bladder cancer, methylation of DAPK, RARbeta, E-cadherin, and p16 could be detected in 45.5%, 68.2%, 59.1%, and 13.6% of the cases, respectively. The sensitivity of methylation analysis (90.9%) was higher than that of urine cytology (45.5%) for cancer detection. Methylation of RARbeta(50%), DAPK (75%), and E-cadherin (50%) was also detected in carcinoma in situ. In 7 normal urothelium samples and 17 normal urine controls, no aberrant methylation was detected except for RARbeta methylation in 3 normal urothelium samples (42.9%) and 4 normal urine samples (23.5%), respectively. CONCLUSIONS: Our results demonstrated a distinct methylation pattern in bladder cancer with frequent methylation of RARbeta, DAPK, E-cadherin, and p16. Detection of gene methylation in routine voided urine using selected markers appeared to be more sensitive than conventional urine cytology.