Accuracy of the routine detection of mutation in mismatch repair genes in patients with susceptibility to hereditary upper urinary tract transitional cell carcinoma

OBJECTIVE: To establish the clinical benefits of systematic testing for hMSH6 and hMLH1 mutations in the very rare patients with upper urinary tract transitional cell carcinomas (UUT-TCCs), a clinical predisposition for hereditary tumour and no mutation detected in hMSH2 gene. PATIENTS AND METHODS: In all, 164 UUT-TCC specimen blocks were screened for microsatellite instability (MSI); 27 (16%) had high MSI levels. Eight patients (30%) had clinical criteria suspicious of hereditary tumour; in three a mutation in hMSH2 was detected. For the other patients, clinical data were collated, and DNA gene sequences analysed to detect mutations in hMLH1 and in hMSH6 genes. RESULTS: Five patients were assessed (mean age at the diagnosis of UUT-TCC 65.2 years, sd 8, range 54-71; two aged < 60 years). Three patients had a personal history of hereditary nonpolyposis colorectal related-cancer (three colorectal). There were only mutations in hMSH2 gene detected, with none in hMSH6 and hMLH1. CONCLUSION: For the rare patients with UUT-TCC who are suspected of carrying mismatch repair gene mutations if no hMSH2 mutation is found by genetic testing, complementary DNA sequencing for hMLH1 and hMSH6 mutation does not seem to contribute and should not be recommended in daily practice.     

The mismatch repair gene hMSH2 is mutated in the prostate cancer cell line LNCaP

PURPOSE: Mismatch repair genes are responsible for the coordinated correction of misincorporated nucleotides formed during DNA replication. Inactivating and inherited mutations in the prototypic mismatch repair gene hMSH2 have been described in a cancer predisposition syndrome known as hereditary nonpolyposis colon cancer. Patients with hereditary nonpolyposis colon cancer are at increased risk for colon cancer and extracolonic cancers such as upper tract transitional cell carcinoma but not prostate cancer. We investigated expression of hMSH2 in prostate cancer cell lines using genetic and molecular analysis. MATERIALS AND METHODS: We used the 3 well described prostate cancer cell lines, DU145, LNCaP and PC3. Western blot analysis with monoclonal antibody to hMSH2 was used to assess expression. Southern blot and polymerase chain reaction of genomic DNA were used to identify genetic alterations in the hMSH2 gene. Single cell cloning, dinucleotide repeats and BAT-26 were used to assess the cell lines for microsatellite instability. RESULTS: The prostate cancer cell line LNCaP did not express hMSH2 and was found to have a homozygous deletion of hMSH2 exons 9 to 16, resulting in truncation of the protein. While microsatellite analysis did not reveal alterations at the BAT-26 locus, single cell cloning produced several LNCaP subclones with alteration at 1 dinucleotide repeat. CONCLUSIONS: The well described prostate cancer cell line LNCaP has a mutation in the hMSH2 gene, resulting in loss of expression and possible evidence of microsatellite instability. To our knowledge our finding is the first demonstration of a genetic alteration in hMSH2 in a prostate cancer cell line.     

膀胱移行细胞癌微卫星不稳定性表达及机理探讨

目的 探讨微卫星不稳定性在膀胱移行细胞癌的表达及其作用机制。方法 用PCR方法分析35例膀胱移行细胞癌尿沉渣标本中微卫星不稳定性表达;用RT-PCR方法监测5种人类错配修复基因在膀胱癌细胞系mRNA转录水平的表达;用PCR方法检测膀胱癌细胞系BIU-87中错配修复基因hMLH1的启动子区域出现异常甲基化。结果 35例膀胱癌患者尿沉渣中,有31例（88.6%)可检出微卫星不稳定性表现;5种人的错配修复基因在BIU-87膀胱癌细胞系中有hMLH1和hMSH2表达缺失,而在正常近曲小管细胞系中都有表达;BIU-87细胞错配修复基因hMLH1的启动子区域出现异常甲基化,应用去甲基化剂处理后可检测到hMLH1的启动子区域的表达,再次去除去甲基化剂后叠不能检测hMLH1的启动子区域。结论 微卫星不稳定性与错配修复基因表达有关。甲基化对膀胱癌细胞系BIU-87错配修复基因hMLH1的表达具有调控作用。     

错配修复基因启动子甲基化与胰腺癌发生的关系

目的通过对胰腺癌错配修复基因启动子甲基化及蛋白表达的检测与微卫星不稳定性的分析,探讨胰腺癌发病的分子机制。方法从35例胰腺癌病人的正常胰腺组织、癌组织中提取DNA;MSP法检测hMLH1及hMSH2基因启动子甲基化状态;SSCP法检测标本中微卫星不稳定性发生情况;免疫组化法检测错配修复基因hMLH1及hMSH2在胰腺癌中的表达情况。结果35例胰腺癌中hMLH1启动子甲基化发生率为60％（21／35）,正常组织中未发现甲基化,两者之间有统计学差异（P〈0.05）;而对于hMSH2仅有1例胰腺癌出现启动子甲基化;35例胰腺癌中微卫星高度不稳定7例,低度不稳定14例,稳定11例,正常组织中没有出现微卫星不稳定,两者之间有统计学差异（P〈0.05）;在微卫星不稳定的21例胰腺癌组织中有19例（90％）出现hMLH1启动子甲基化现象,微卫星稳定的ll例胰腺癌组织中仅有2例（6％）出现hMLH1启动子甲基化。hMLH1启动子甲基化在微卫星不稳定胰腺癌组织中常为缺失表达或低表达,在微卫星稳定胰腺癌组织中呈正常表达。hMSH2无论在MSI-H或MSI-L胰腺癌与正常胰腺组织中均无缺失表达,仅部分低表达。结论胰腺癌组织中错配修复基因的缺陷主要是hMLH1启动子甲基化,与胰腺癌微卫星不稳定性及蛋白表达缺失有关,在胰腺癌发生过程中起重要作用,是胰腺癌发生的重要机制之一。     

膀胱移行细胞癌错配修复基因hMLH1、hMSH2、hMSH3启动子甲基化状态的研究

目的 探讨错配修复基因hMLH1、hMSH2、hMSH3在膀胱移行细胞癌中启动子甲基化和蛋白表达的相关性.方法 采用甲基化特异聚合酶链反应(MSP)检测正常膀胱上皮组织(13例)及膀胱移行细胞癌组织(57例)hMLH1、hMSH2、hMSH3启动子甲基化状态,免疫组织化学检测其蛋白表达.结果 在正常膀胱上皮中,hMLH1、hMSH2、hMSH3均未发现启动子甲基化;在肿瘤组织中,hMSH2未发现启动子甲基化,hMLH1、hMSH3启动子甲基化阳性率分别为36.8%、49.1%,与正常组织比较差异均有统计学意义(P＜0.01),但在不同肿瘤分级(G1、G2、G3)间及不同临床分期(浅表性、浸润性)间比较差异无统计学意义(P＞0.05).免疫组织化学显示:hMLH1、hMSH2、hMSH3蛋白表达在正常膀胱上皮组织中,阳性表达率分别为100%、100%、92.3%,与肿瘤组织阳性表达率分别为59.6%、52.6%、40.4%,两者比较差异有统计学意义(P＜0.01),但在不同临床分期(浅表性、浸润性)间比较差异无统计学意义(P＞0.05),且hMSH2、hMSH3蛋白阳性表达率随肿瘤分级的增加显著降低,G1与G3比较差异有统计学意义(P＜0.05).在肿瘤组织中,hMLH1和hMSH3启动子甲基化与蛋白表达具有极显著相关性(P＜0.01).结论 hMLH1、hMSH3蛋白表达受其启动子甲基化的调控,hMSH2蛋白表达不受其启动子甲基化的调控.错配修复基因hMLH1、hMSH2、hMSH3蛋白表达的缺失可能参与了膀胱移行细胞癌的发生.     

脑胶质瘤中hMLH1、hMSH2基因启动子区的甲基化状态研究

目的 检测脑胶质瘤中hMLH1、hMSH2基因启动子区的甲基化状态,探讨其在肿瘤发生中的作用.方法 采用甲基化特异性聚合酶链反应(MSP)方法,检测51例脑胶质瘤标本及人脑胶质瘤U251细胞株的hMLH1、hMSH2基因启动子C_PG岛甲基化状态.结果 在7例正常脑组织中,用MSP法检测的hMLH1、hMSH2基因启动子区均未发现甲基化,51例脑胶质瘤组织中,hMLH1、hMSH2甲基化率分别为13.7%(7/51)、35.3%(18/51),且为甲基化和非甲基化共存,人脑胶质瘤U251细胞中未发生hMLH1启动子甲基化,而发生了hMSI-12启动子甲基化,hMLH1、hMSH2基因启动子区甲基化与性别、年龄、病理类型无明显相关.但hMLH1在低级别(Ⅰ～Ⅱ级)患者标本中甲基化率为0.0%(0/25),高级别(Ⅲ～Ⅳ级)患者标本中甲基化率为26.9%(7/26),差异有统计学意义(χ~2=5.69,P<0.05).结论 hMLH1、hMSH2基因启动子区甲基化状态与性别、年龄、病理类型无明显相关.hMSH2基因启动子区的CpG岛在脑胶质瘤中有中等频率的甲基化,是脑胶质瘤发生过程中的早期事件,可能与脑胶质瘤的发生相关;脑胶质瘤中hMLH1基因启动子区甲基化率较低,但hMLH1启动子区甲基化状态与病理分级有关;人脑胶质瘤U251细胞株中hMSH2基因启动子C_PG岛高甲基化.     

Expression of vascular endothelial growth factor protein in human renal cell carcinoma

OBJECTIVE: To evaluate the effect of vascular endothelial growth factor (VEGF, one of the most important angiogenetic factors) in renal cell carcinoma (RCC) by analysing many RCCs for the expression of immunohistochemical (IHC) VEGF-staining related to clinicopathological findings and survival. PATIENTS AND METHODS: VEGF immunostaining was examined with the tissue microarray (TMA) method on tumour samples from 229 patients and validated in 71 by ordinary tissue sections (TS). IHC VEGF expression was quantified by estimating the volume density and staining intensity on a three-grade scale. RESULTS: In most RCCs there was VEGF staining in the cell cytoplasm and membrane. In cell membranes the VEGF expression declined with storage time. IHC VEGF expression analysed by TMA and TS gave corresponding results. There was no difference in VEGF expression among conventional, papillary and chromophobe RCCs. There were significant correlations between VEGF expression and tumour size and stage. In univariate analysis VEGF expression correlated with survival, especially in conventional RCCs; this prognostic information was lost in multivariate analysis. The VEGF staining intensity correlated only with VEGF expression but not with any clinicopathological factors. CONCLUSIONS: VEGF protein was present in most RCC cells. There was no difference in VEGF expression among the different RCC types. The correlation between VEGF expression and tumour stage and with prognosis indicates the significance of VEGF within tumour growth and progression in RCC.     

Microsatellite instability and mismatch repair target gene mutations in cell lines and xenografts of prostate cancer

BACKGROUND: Mismatch repair (MMR) and microsatellite instability (MSI) occur in prostate cancer, but their role has not been well documented. METHODS: In 6 cell lines and 22 xenografts from prostate cancer, PCR and gel electrophoresis were performed to detect MSI by analyzing microsatellite markers BAT-25 and BAT-26 and to detect frameshift mutations in mononucleotide repeats in BAX, IGF2R, MSH3, MSH6, and TGFBR2. RESULTS: Four of 6 (67%) cell lines and 3 of 22 (14%) xenografts showed MSI. At least 1 frameshift mutation was detected in the same 4 (67%) cell lines and in 5 of 22 (23%) xenografts. While MSH3 was frequently mutated in cell lines, BAX and TGFBR2 showed frequent alterations in both cell lines and xenografts. CONCLUSIONS: MSI related to MMR deficiency is relatively frequent in high-grade tumors, and mutations in MSI target genes involved in cell death and proliferation appeared to be selected for during prostatic carcinogenesis.     

错配修复蛋白hMLH1、hMSH2和hMSH6在散发性结直肠癌中的表达及意义

目的探讨三种错配修复蛋白hMLH1、hMSH2和hMSH6在散发性结直肠癌(SCRC)中的表达情况及临床意义。 方法随机选取空军总医院普通外科和北京大学肿瘤医院结直肠外科自2008年3月至2012年12月收治的SCRC患者290例,采用免疫组织化学SP法检测患者肿瘤组织中hMLH1、hMSH2、hMSH6蛋白的表达情况,并结合其临床病理参数进行回顾性分析。 结果290例SCRC患者的肿瘤组织中hMLH1蛋白表达缺失率13.4%(39/290),hMSH2表达缺失率12.1%(35/290), hMSH6表达缺失率29.0%(84/290); hMLH1/hMSH2共同缺失率3.8%(11/290), hMLH1/hMSH6共同缺失率10.0%(29/290),hMSH2/hMSH6共同缺失率7.2%(21/290)、hMLH1/hMSH2/hMSH6共同缺失率3.4%(10/290)。hMSH1蛋白在中分化腺癌和低分化、黏液癌组织中表达率明显高于高分化腺癌(P<0.01); hMSH2蛋白在直径≤5 cm的肿瘤组织中的表达率显著高于直径>5 cm的肿瘤组织(P<0.01);hMSH6蛋白在女性组中的表达率显著低于男性组(P<0.01),在直径≤5 cm的肿瘤组织中的表达率高于直径>5 cm的肿瘤组织(P<0.05),有脉管内癌栓组的表达率高于无脉管内癌栓组(P<0.05),且在淋巴结转移多的组织中表达率高于淋巴结低转移者(P<0.01)。hMLH1与hMSH2的表达无明显相关性,而hMSH6与hMLH1、hMSH2的表达均呈明显相关性。 结论在SCRC中,错配修复蛋白hMLH1、hMSH2、hMSH6的表达缺失并不少见,且其表达缺失与SCRC临床病理参数的关系也明显不同于遗传性非息肉病性大肠癌。因此,当hMLH1、hMSH2、hMSH6作为对SCRC患者行肿瘤恶性度评定或制定个体化的化疗方案和预后判断的参考指标时,其标准也不同于遗传性非息肉病性大肠癌。     

hMLH1及hMSH2蛋白免疫组化结合微卫星不稳定性检测在遗传性非息肉病性结直肠癌家系筛选中的作用

目的 探讨hMLH1及hMSH2蛋白免疫组化结合微卫星不稳定性检测在遗传性非息肉病性结直肠癌家系筛选中的敏感性、特异性及临床应用价值。方法 对12例符合Amsterdam标准的HNPCC患者和16例散发性结直肠癌患者的肿瘤标本进行hMLH1及hMSH2蛋白免疫组化检查和微卫星不稳定性检测。结果 hMLH1及hMSH2蛋白免疫组化筛选HNPCC家系的敏感性为91．7％,特异性为87．5％;微卫星不稳定性检测的敏感性为100％,特异性为75．0％;两者结合敏感性为91．7％,特异性为93．8％。结论 hMLH1及hMSH2蛋白免疫组化结合微卫星不稳定性检测筛选HNPCC家系敏感性和特异性明显提高,而且方法简单、经济,适合在临床广泛应用。     

Infrequent microsatellite instability in urothelial cell carcinoma of the bladder in young patients

OBJECTIVE: Defects in the DNA mismatch repair result in microsatellite instability (MSI), which characterise most tumours related to the hereditary non-polyposis colorectal cancer syndrome and some sporadic tumours. Several studies have reported the occurrence of MSI in urothelial cell carcinoma (UCC) of the bladder with a particularly high incidence in tumours from young patients. In this study, we have evaluated the occurrence of MSI in primary bladder UCC arising in seventeen young patients selected for being below 45 years of age at diagnosis. METHODS: Microsatellite analysis has been performed using the panel of five quasimonomorphic mononucleotide repeats (BAT-25, BAT-26, NR-21, NR-24, NR-27) recently recommended to detect MSI tumours. The original Bethesda panel including BAT-25, BAT-26 and three dinucleotide repeats (D2S123, D5S346, D17S250) has further been studied in 10 UCC samples. RESULTS: MSI has been observed in only one of the 17 bladder UCC studied. Using the original Bethesda panel, identical results were obtained, indicating that the panel of five mononucleotide markers adequately detected MSI in UCC tumours. CONCLUSIONS: Our data indicate that classical MSI affecting mono- or di-nucleotides are rarely involved in bladder UCC developing in young patients. Further studies using gold standard criteria would help clarifying the involvement of MSI in the pathogenesis of bladder UCC.     

Expression of the SART1 tumor rejection antigen in renal cell carcinoma

We have previously described the SART1 gene, which encodes both the SART1₂₅₉ antigen expressed in the cytosol of the majority of squamous cell carcinomas and some adenocarcinomas and the SART1₈₀₀ antigen expressed in the nucleus of the majority of proliferating cells. The SART1₂₅₉ antigen is recognized by HLA-A24 and A26-restricted cytotoxic T lymphocytes (CTLs). The present study investigated the expression of these two antigens in renal cell carcinomas (RCCs) in order to identify an appropriate molecule for use in specific immunotherapy for RCC patients. These two antigens were detected in all RCC cell lines and cells of the primary cultures of the RCCs tested. Further, they were detectable in cells of the primary cultures of non-tumorous kidney tissues. In contrast to these cultured cells, SART1₂₅₉ was detectable in only a few uncultured RCC tissues (5/20, 25%) and was undetectable in non-tumorous kidney tissues. SART1₈₀₀ was also scarcely detectable in uncultured RCC tissues (3/20, 15%) and non-tumorous kidney tissues (4/20, 20%). HLA-A2402-restricted and tumor-specific CTL (KE4-CTL) used for the cloning of the SART1 gene showed significant levels of cytotoxicity to both the cells from the RCC cell line and the cells from the primary cultures of RCC tissues, but did not lyse any normal cells, including cells from the primary cultures of non-tumorous kidney tissues. The SART1-derived peptide at positions 690–698 induced HLA-A24 restricted CTLs cytotoxic to RCC cells from peripheral blood mononuclear cells (PBMCs) of RCC patients. Therefore, the SART1 peptide could be an appropriate molecule for use in peptide-based specific immunotherapy for RCC patients. Received: 22 October 1999 / Accepted: 11 January 2000     

A meta-analysis of the prevalence of somatic mutations in the hMLH1 and hMSH2 genes in colorectal cancer

Aim The study aimed to understand better the somatic mutations in the human MutL Homolog 1 (hMLH1) and human MutS Homolog 2 (hMSH2) genes in colorectal cancer (CRC) and to investigate the differences derived from ethnicity, family history, detection method and microsatellite instability (MSI). Method The terms ‘hMSH2’ or ‘hMLH1’and‘colorectal cancer’‘colorectal carcinoma’ or ‘colorectal tumour’ were searched in the PubMed, Springer, Lippincott, Williams & Wilkins and HighWire Press databases for the publication period December 1993 to September 2010. The Comprehensive Meta Analysis V2 software (Biostat Inc.) was used to explore the prevalence and 95% confidence intervals. Results The prevalence of somatic mutations in the hMLH1 and hMSH2 genes in CRC was 0.15 (95% CI 0.10–0.22) and 0.10 (95% CI 0.07–0.16), respectively. A higher prevalence of somatic mutations in hMSH2 was found in hereditary non‐polyposis CRC than in sporadic CRC: 0.36 (95% CI 0.14–0.67) and 0.10 (95% CI 0.07–0.13) respectively. In addition, a higher prevalence of somatic mutations in the hMLH1 gene was observed relative to hMSH2 in the European group. The prevalence was higher in the high‐level instability (MSI‐H) group than in both the low‐level instability (MSI‐L) and the microsatellite stable (MSS) groups. Conclusion Somatic mutations in the hMLH1 and hMSH2 genes play a vital role in CRC and a high prevalence was found in this meta‐analysis. Furthermore, more studies are needed which focus on somatic mutations in the American population and in patients with MSI‐L and MSS.     

大肠腺瘤及其癌变组织hMLH1和hMSH2表达及其临床意义

目的　探讨错配修复基因hMLH1和hMSH2在大肠腺瘤癌变中的意义。方法　采用免疫组化方法对 6 3例大肠腺瘤、2 0腺瘤癌变、2 0例大肠癌的hMLH1和hMSH2表达进行了检测。结果　显示错配修复基因hMLH1、hMSH2在大肠腺瘤、腺瘤癌变和大肠癌表达率逐渐降低 ,且随腺瘤不典型增生加重表达率也逐渐降低 ,hMLH1、hMSH2表达缺失率与肿瘤发生部位相关 ,右半结肠明显高于左半结肠。结论　DNA错配修复基因功能缺失与大肠癌的发生有关 ,可能系大肠癌发生过程中的早期事件 ,且左、右半结肠大肠癌的发生机制可能有所不同。     

微卫星不稳定结直肠癌hMLH1和hMSH2及hMSH6种系突变与hMLH1启动子甲基化检测

目的探究微卫星不稳定（MSI）结直肠癌患者的hMLH1、hMSH2和hMSH6种系突变特征和hMLH1启动子甲基化状态。方法对前瞻性收集的34例MSI结直肠癌患者检测其hMLH1、hMSH2和hMSH6种系突变，并研究其肿瘤的hMLH1启动子甲基化状态。结果34例MSI结直肠癌中。共检测到MLH1基因启动子的甲基化19例（55．9％）。19例MSI—H结直肠癌中检测到MLH1基因的甲基化14例（73．7％）；15例MSI—L结直肠癌检测到MLH1基因的甲基化5例（33．3％）；两组差异有统计学意义（P〈0．05）。全组共发现8个hMSH2和hMSH6基因的突变，其中hMSH6基因突变3个，hMSH2基因突变5个。结论中国人MSI结直肠癌错配修复基因突变（未测到MLH1基因突变）和MLH1基因启动子的甲基化检出率可能有别于国外MSI结直肠癌。     

Study on in vitro invasive potential of renal cell carcinoma cell lines and effect of growth factors (EGF and TGF-beta 1) on their in invasions

Renal cell carcinomas (RCCs) frequently metastasize to distant organs in their clinical course. However, the mechanism of the metastasis had not been fully elucidated. In vitro invasion assay has been reported to be a rapid method for the evaluation of the invasive potential of various malignant cells. In vitro invasive potential of RCC has not been investigated by this method. Thus, in the present study, we first attempted to characterize the in vitro invasive potential of four human RCC cell lines which had been established in our institute. Secondly, we investigated the influence of two growth factors (EGF, TGF-beta 1) on the invasive potential of these cell lines when the two factors were applied as chemoattractants. SMKT-R-3 and R-4 cell lines showed more cell penetration through Matrigel than SMKT-R-1 and R-2 cell lines, suggesting that the former cell lines have higher invasive potential. While invasive potential varied in each cell line, it was enhanced by EGF in all cell lines. However, TGF-beta 1 suppressed the invasive potential of all four cell lines. These results suggest that two factors have different actions on the invasion of RCCs.     

What is the best way to assess microsatellite instability status in colorectal cancer? Study on a population base of 462 colorectal cancers

The assessment of the microsatellite instability (MSI) status in colorectal cancers is presently warranted for three reasons: 1) as a screening tool for hereditary nonpolyposis colorectal cancer, 2) as a prognostic marker, and 3) as a potential predictive factor of chemotherapy response. The aim of this study was to evaluate, on a large scale with tissue samples coming from a number of different sources, the difficulties met with routine use of immunohistochemistry (IHC) and to determine if it really does offer an accurate alternative to PCR genotyping. Colorectal carcinomas from 462 consecutive patients resected in public or private hospitals were assessed for MSI status by two methods: MSI testing (with BAT-26 microsatellite) and IHC detection of hMLH1, hMSH2, and hMSH6 proteins. Of the 398 cancers tested, immunohistochemistry was noncontributory in 42 (10.5%), focal in 9 (2.3%), and discordant with the PCR results in 36 (9%). For these 87 cases, complementary analyses were performed to explain discrepancy. After additional IHC assay with modified processing protocols, 8 cases remained noncontributory, 2 focal, and 28 discordant: 18 microsatellite stability IHC/MSI PCR and 10 MSI IHC/microsatellite stability PCR. For these discordant cases, we performed a multiplex PCR assay on DNA extracted from the frozen sample and BAT-26 was amplified from DNA extracted from the paraffin blocks used for IHC. Four discordant cases were reclassified after PCR multiplex assay (3 as MSI and 1 as microsatellite stability). Five other cases displayed intratumoral heterogeneity and 19 remained discordant. The discrepancy could be partly explained by variable technical protocols of fixation in the different laboratories, leading to variations in staining quality and difficulties in IHC interpretation. This population-based study is the first one to show that IHC is not sensitive and specific enough to be used routinely. Immunohistochemistry analysis of MMR proteins must be performed in standardized conditions and interpreted by confirmed pathologists. It cannot replace PCR as long as protocols are not optimized and harmonized.     

膀胱移行细胞癌中DNA错配修复基因hMLH1、hMSH2和hMSH3启动子区甲基化状态研究

目的探讨DNA错配修复基因启动子区CpG岛甲基化状态及其在膀胱移行细胞癌（BTCC）中的表达。方法应用MSP技术检测膀BTCC中hMLH1、hMSH2和hMSH3基因启动子区甲基化状态,RT-PCR法检测其mRNA表达水平。结果36例BTCC组织中hMSH1、hMSH2的甲基化阳性率分别为38.9％（14／36）、52.8％（19／36）,所有标本中均未发现有hMSH3启动子甲基化。hMLH1、hMSH2、hMSH3 mRNA在BTCC中表达率分别为47.2％（17／36）、38.9％（14／36）、16.7％（6／36）,在正常组织中分别为22.2％（8／36）、63.9％（23／36）、0％（0／36）,差异均有统计学意义（P〈0.01）,并且随肿瘤病理分级的增加呈下降趋势（P〈0.05）,均与临床分期不相关（P〉0.05）。结论hMLH1、hMSH2和hMSH3基因启动子异常甲基化可能导致该基因转录表达失活,使其mRNA表达减少甚至缺失,这可能是导致BTCC发生、发展的原因之一。