遗传性非息肉性结直肠癌患者腺瘤和癌组织微卫星基因型分析

背景：遗传性非息肉性结直肠癌（HNPCC）是一种由错配修复基因种系突变引起的常染色体显性遗传病，高度微卫星不稳定（MSI—H）为其分子生物学特征之一。目的：利用5个微卫星位点建立正常结直肠黏膜、结直肠腺瘤和癌组织的微卫星基因型，探讨HNPCC的MSI发生情况和MSI检测的临床意义。方法：纳入源自33个HNPCC家系的腺瘤28例和腺癌14例，其中4例为同步腺瘤-癌；以32例散发性结直肠腺瘤和24例散发性结直肠癌作为对照。选用BAT25、BAT26、D2S123、D5S346、D17S250五个微卫星位点行荧光标记聚合酶链反应（PCR），以GeneMapper软件分析PCR产物。通过与正常黏膜微卫星序列PCR片段长度进行比较，判定腺瘤和癌组织的MSI情况。结果：HNPCC腺瘤和癌组织MSI-H发生率分别显著高于散发性结直肠腺瘤和结直肠癌（64-3％对3．1％，71.4％对12．5％，P〈0．05）。4例同步腺瘤-癌均表现为MSI—H．其腺瘤和癌组织的MSI类型不同。结论：HNPCC腺瘤和癌组织MSI—H发生率高。同步腺瘤一癌来源于不同克隆。MSI检测可作为HNPCC的临床初筛方法。     

错配修复蛋白和p53蛋白在结直肠癌中的表达及其临床意义

背景:研究表明,结直肠癌的主要发病途径有两条,即染色体不稳定性途径和微卫星不稳定性(MSI)途径。目的:探讨错配修复蛋白(MMRP)和p53蛋白在结直肠癌中的表达及其临床意义。方法:采用免疫组化SP法检测2013年1月—2017年12月上海市嘉定区中心医院收治的276例结直肠癌中4种MMRP和p53蛋白表达,并分析其与临床病理特征的关系。分析MSI对结直肠癌患者生存情况的影响。结果:MMRP表达缺失36例(13.0%),MSI与组织病理学类型、TNM分期和血吸虫感染有关(P<0.05),而与患者性别、年龄、发病部位、分化程度和淋巴结转移均无关(P>0.05)。p53蛋白在结直肠癌中的阳性表达率为44.9%,其表达与组织病理学类型、TNM分期、淋巴结转移和血吸虫感染有关(P<0.05),而与患者性别、年龄、发病部位和分化程度均无关(P>0.05)。MSI与p53表达呈负相关(r=-0.169,P<0.05)。MSI组和MSS组的1、3、5年生存率分别为100%、97.2%、83.1%和96.7%、81.9%、38.9%,差异有统计学意义(χ^2=12.582,P=0.001)。结论:MSI和p53表达与结直肠癌的临床病理特征关系密切,对肿瘤的恶性程度和预后的判断有指导意义。MSI与p53表达呈负相关,提示两者可能参与结直肠癌不同阶段的发生、发展过程。     

结直肠癌中TRPV6蛋白表达及其与临床病理学特征和预后相关性分析

目的 探讨结直肠癌组织中TRPV6蛋白表达情况，并分析其与患者相关临床病理学特征及预后的相关性。方法 应用免疫组织化学法检测65例结直肠癌石蜡组织中TRPV6蛋白表达情况，PCR法检测结直肠癌石蜡组织中微卫星稳定和KRAS基因突变情况，采用SPSS 24.0统计学软件分析TRPV6阳性表达与患者临床病理特征及预后的相关性。结果 TRPV6蛋白明确表达于肿瘤细胞及正常肠道黏膜上皮细胞膜；65例结直肠癌TRPV6阳性率为24.62%,高于正常对照肠黏膜，二者表达存在显著差异(P<0.05)。TRPV6阳性表达与肿瘤远处转移(P=0.029)、肿瘤组织微卫星状态(P=0.027)及KRAS癌基因突变显著相关(P=0.018),而与患者性别、年龄、肿瘤部位、分化程度、组织学类型、淋巴结转移、临床分期等均未显示显著相关。结论 TRPV6蛋白可能参与了结直肠癌的发生、发展，其确切作用机制有待进一步深入研究。     

散发性结直肠癌中hMSH2与PTEN的表达及临床意义

目的:研究错配修复蛋白hMSH2与PTEN在散发性结直肠癌的表达变化及两者之间的关系,以进一步探讨其临床意义.方法:采用SP免疫组织化学两步法对42例散发性结直肠癌、相应近端癌旁组织(距癌组织3 cm)和远端癌旁组织(距癌组织>10 cm)及15例正常结直肠组织进行hMSH2与PTEN蛋白袁达检测.同时Western blot法检测42例散发性结直肠癌、相应远端对照组织hMSH2与PTEN蛋白表达.分析散发性结直肠癌发病机制及hMSH2与PTEN蛋白表达与临床病理之间的关系.结果:结直肠癌组织中,hMSH2与PTEN蛋白失表达率(阴性率)均低于正常结直肠组织及近端癌旁组织、远端癌旁组织(X2hMSH2=7.967,X2PTEN=11.67,均P<0.05).PTEN蛋白表达与肿瘤分化程度呈正相关(rs=0.727,P<0.05),与Dukes分期、侵润深度、淋巴结转移、肝转移均呈负相关(rs=-0.727,-0.718,-0.718,-0.535,均P<0.05).hMSH2蛋白表达与上述临床病理特征未见明显相关.hMSH2与PTEN蛋白表达在散发性结直肠癌中呈正相关(rs=0.679,P<0.05).与远端对照组织相比42例胃癌组织中hMSH2蛋白低表达率为59.52%(25/42),PTEN低表达率为45.24%(19/42).结论:PTEN表达与其临床病理特征相关;在散发性结直肠癌发生、发展过程中错配修复蛋白hMSH2表达缺失伴有PTEN蛋白表达下调.     

CpG岛甲基子表型阳性的散发性大肠癌的临床病理特征

目的 探讨CpG岛甲基子表型阳性的散发性大肠癌的临床病理特征.方法 采用甲基化特异性PCR方法对71例散发性大肠癌患者行p14、hMLH1、p16、MGMT和MINT1共5个基因启动子甲基化检测,分析CpG岛甲基子表型阳性的散发性大肠癌的临床病理特征.结果 71例散发性大肠癌患者中共检出CpG岛甲基子表型阳性者15例,阳性率为21.1%.CpG岛甲基子表型阳性的散发性大肠癌中右半结肠癌（40.0%比12.5%,P＜0.05）、低分化癌（46.7%比14.3%,P＜0.05）、淋巴结转移（86.7%比48.2%,x2=7.112,P＜0.05）、Dukes C期或D期（86.7%比50.0%,x2=6.519,P＜0.05）所占比例均显著高于CpG岛甲基子表型阴性者.结论 CpG岛甲基子表型阳性的散发性大肠癌具有右半结肠癌多发、低分化多见、常有淋巴结转移和分期较晚的特点.     

Diversin在结直肠癌中表达及与临床病理因素的关系

目的研究Diversin在结直肠癌组织中的表达及与临床病理因素的关系。方法收集沈阳医学院附属中心医院病理科结直肠癌蜡块组织51例及配对的癌旁组织,采用EnVision两步法检测Diversin在结直肠癌组织及癌旁组织中的免疫组织化学表达。结果 Diversin在结直肠癌组织阳性表达率(80.39%)明显高于癌旁组织(9.80%),且Diversin在不同分化程度,临床分级,淋巴结转移的结直肠癌患者中差异有统计学意义(P0.05)。结论 Diversin在结直肠癌中高表达,并且与结直肠癌患者的分化程度、临床分级、淋巴结转移有关,可能成为结直肠癌诊治的生物学标记物。     

微卫星不稳定状态与结直肠癌患者临床病理特征的相关性研究

目的探究微卫星不稳定(MSI)状态与结直肠癌患者临床病理特征的相关性。方法采用回顾性队列研究方法,收集2015年1月至2019年12月南京医科大学第一附属医院结直肠外科1280例结直肠癌手术患者的临床病理资料,其中男性800例,女性480例;中位年龄为63岁;右半结肠癌337例,左半结肠癌398例,直肠癌545例。PCR方法检测肿瘤标本的微卫星状态。依据MSI状态,将患者分为高度微卫星不稳定性(MSI-H)组和微卫星稳定性(MSS)/低度微卫星不稳定性(MSI-L)组。观察人口学特征,手术标本病理学检查,微卫星状态等指标。计数资料以绝对数或百分比表示,组间比较采用卡方检验或Fisher精确检验。等级资料采用秩和检验。非正态分布资料,采用中位数M(P25,P75)表示,组间比较采用曼-惠特尼U检验。结果在1280例患者中,112例(8.7%)为MSI-H,79例(6.2%)为MSI-L,1089例(85.1%)为MSS。MSI-H组与MSS/MSI-L组患者在术前血清CEA(χ²=6.943,P<0.05)、肿瘤部位(Z=-9.451,P<0.001)、肿瘤TNM分期(Z=-2.108,P<0.05)、肿瘤T分期(Z=-2.397,P<0.05)、肿瘤N分期(Z=-3.892,P<0.001)、肿瘤分化(χ²=6.663,P<0.05)、肿瘤黏液成分(χ²=78.833,P<0.001)、肿瘤最大直径(χ²=39.656,P<0.001)、癌结节(χ²=8.759,P<0.05)、神经侵犯(χ²=10.238,P<0.05)、淋巴结转移率(LNR)(χ²=5.880,P<0.05)、淋巴结检出数(Z=-5.019,P<0.001)、阳性淋巴结检出数(Z=-3.667,P<0.001)等方面差异有统计学意义,主要表现为,MSI-H组患者CEA<4.7 ng/mL、右半结肠癌、低TNM分期、高T分期、低N分期、低分化、黏液成分、肿瘤直径≥4 cm、无癌结节、无神经侵犯、低LNR所占比例显著高于MSS/MSI-L组患者。MSI-H组淋巴结检出数显著多于MSS/MSI-L组,而阳性淋巴结检出数显著较少。结论MSI-H结直肠癌患者具有较为特殊的临床病理特征,其中既有预后良好的,亦有预后不良的特征。     

结直肠癌中HMGA2表达的意义与微卫星不稳定性的关系

目的探讨高迁移率族蛋白(HMG) A2在结直肠癌组织中表达意义及与微卫星不稳定性(MSI)的关系。方法结直肠癌手术标本70例,采用免疫组化法检测微卫星不稳定四种相关蛋白MLH1、MSH2、MSH6、PMS2及HMGA2的表达情况,分为高频微卫星不稳定组(MSI-H)、低频微卫星不稳定(MSI-L)/微卫星稳定组(MSS)两组,研究HMGA2与MSI的相关性及与结直肠癌临床特征之间的关系,进一步用Western印迹法验证免疫组化结果。结果结直肠癌中HMGA2阳性率为65. 71%(46/70),与正常肠黏膜相比差异显著(P<0. 001),低分化癌组高于中、高分化癌组,差异有意义(P<0. 05); TNMⅢ+Ⅳ期明显高于Ⅰ+Ⅱ期(P<0. 05)。MSI-H发生率为17. 14%(12/70),右半结肠发生率高于左半结肠(P<0. 05),此外,MSI-H发生与患者年龄、肿瘤分化程度有关(P<0. 05)。MSI-H组、MSI-L/MSS组中HMGA2的表达差异无统计学意义(P>0. 05)。结论HMGA2高表达可能促进结直肠癌的发生与发展,作用机制与微卫星状态无关,需要进一步研究。     

肿瘤浸润淋巴细胞在结直肠癌中的临床病理分析

目的:探讨结直肠癌中肿瘤浸润淋巴细胞(TIL)的临床病理和免疫组织化学特征, 及大量TIL与各病理因素的关系.方法:利用光镜和免疫组织化学法对370例结直肠癌中的肿瘤浸润淋巴细胞进行组织病理学观察, 并分析对比其与各临床病理因素的相关性.结果:81.9%的结直肠癌中可见淋巴细胞散在分布, 数量少, 18.1%却可见大量的淋巴细胞,并有一定的临床病理特征. 大量的TIL部分侵入肿瘤实质而部分位于肿瘤组织周围. 免疫组织化学染色显示, 肿瘤浸润淋巴细胞主要是由CD3+ T细胞、CD20+、CD79α+B细胞、浆细胞和CD56+NK细胞构成, 其中细胞毒性TIA-1均有较高的表达, 并伴有大量淋巴细胞浸润与肿瘤组织的分化程度、浸润深度及淋巴结转移有关(χ2 = 4.954, 11.240及12.768; P = 0.026,0.001及0.000).结论:结直肠癌组织中TIL的病理形态差异较大并与临床病理因素相关. 在结直肠癌中伴有大量肿瘤浸润淋巴细胞存在时有积极的意义.     

hMLH-1和hMSH-2蛋白在新疆汉族散发性大肠癌中的表达及意义

目的:探讨错配修复基因hMLH-1和hMSH-2蛋白在新疆汉族散发性大肠癌(sporadic colorectal carcinoma,SCC)中的表达情况及其与SCC病理参数的关系.方法:采用免疫组织化学方法检测95例汉族SCC组织和65例正常结直肠组织(normal colorectal mucosa,NCM)中hMLH-1和hMSH-2蛋白的表达情况.结果:hMLH-1和hMSH-2在NCM中均表达.hMLH-1蛋白在SCC组织中缺失率为(31.6%)与NCM比较有显著差异(P<0.05);hMSH-2蛋白在SCC组织中缺失率(18.9%)与NCM比较有显著差异(P<0.05).hMLH-1在右半结肠癌中缺失率高于左半结肠癌和直肠癌(P=0.006),在低分化腺癌和黏液腺癌中缺失率明显高于高-中分化腺癌(P=0.014);hMSH-2蛋白在右半结肠癌中缺失率高于左半结肠癌和直肠癌(P=0.002),低分化腺癌和黏液腺癌中缺失率显著高于高-中分化腺癌(P=0.008).在SCC组织中,hMLH-1和hMSH-2蛋白表达呈正相关性(r=0.224,P<0.05).结论:hMLH-1和hMSH-2蛋白在新疆地区汉族散发性大肠癌中有一定比例的缺失,且与肿瘤分化程度和发生部位密切相关,hMLH-1和hMSH-2蛋白联合检测可能为判断散发性直肠癌恶性程度和临床预测提供重要参考.     

Microsatellite Instability and Mutations in DNA Mismatch Repair Genes in Sporadic Colorectal Cancers

PURPOSE: This study was designed to investigate the frequency of mutations in DNA mismatch repair genes in sporadic colorectal cancers. METHODS: Genomic DNAs procured from paraffin blocks of the pathologic specimens from 230 consecutive patients with colorectal cancer were examined for their microsatellite instability status using a mononucleotide microsatellite marker, BAT-26, and also evaluated expressions of hMLH1, hMSH2, and hMSH6 proteins by immunohistochemical staining. Any of these 230 patients did not have family histories of hereditary nonpolyposis colorectal cancer, familial adenomatous polyposis, colorectal cancer, or hereditary nonpolyposis colorectalrelated cancers, such as endometrial, small bowel, and ureteral and renal pelvic cancers. When microsatellite instability was positive, mutations in the simple repeated sequences of TGF-RII, BAX, IGF IIR, hMSH3, and hMSH6 genes were examined. In microsatellite instability–positive or staining-negative cases, polymerase chain reaction–single- strand conformation polymorphism and DNA sequencing detected mutations of hMLH1, hMSH2, and hMSH6 genes. If mutations were found in tumor tissue samples, we tested for a germline mutation with a microdissected corresponding normal tissue. RESULTS: Among 230 cases of sporadic colorectal cancer, 21 (9.1 percent) manifested microsatellite instability. In the immunohistochemical staining, 20 (8.6 percent) showed loss of expressions. All 20 staining-negative cases were microsatellite instability–positive. Only 1 of 21 (4.8 percent) microsatellite instability– positive cases showed intact staining for three proteins. The frame-shift mutations of the simple repetitive sequences were found in 17 cases (81.0 percent) in TGF-RII, 11 (52.4 percent) in BAX, 5 (23.8 percent) in IGF IIR, 7 (33.3 percent) in hMSH3, and 8 (38.1 percent) in hMSH6 genes. Germline mutation was observed in only one case, which accounts for 4.8 percent among positive microsatellite instability and 0.4 percent of total patients, and was found in hMSH2. Five somatic mutations (2 in hMLH1, 2 in hMSH2, and 1 in hMSH6) also were found. CONCLUSION: The results indicated that a germline mutation of DNA mismatch repair gene was a rare event in sporadic colorectal cancers.     

Early-Age-at-Onset Colorectal Cancer and Microsatellite Instability as Markers of Hereditary Nonpolyposis Colorectal Cancer

PURPOSE: Early-age-at-onset colorectal cancer and microsatellite instability are characteristic features of hereditary nonpolyposis colorectal cancer. Our aim was therefore to investigate whether these features might be useful markers in screening for hereditary nonpolyposis colorectal cancer and mismatch repair gene mutations. METHODS: From 1,132 consecutive patients who underwent surgery for colorectal cancer at our department between 1980 and 1999, we selected all patients 40 years of age or younger (study group, n = 59) and a subset of patients 40 years of age or older (control group, n = 60) who were matched for gender and pathologic TNM stage. Patients for whom a complete family cancer history or microsatellite status was unavailable were excluded from the study. Family cancer histories, retrieved from archival charts, were reassessed. Microsatellite status was investigated with the five microsatellites from the Bethesda recommended panel (BAT-26, BAT-25, D2S123, D5S346, and D17S250). On the basis of the number of altered microsatellites ( 2, 1, or 0), tumors were considered as having high or low instability or microsatellite stability, respectively. Mutation analysis for MLH1 and MSH2 genes was performed only in cases of high instability. DNA was investigated for mutations by single-strand conformational polymorphism and sequencing analysis. RESULTS: Data from 95 patients (study group: n = 37, 18 males, mean age 35 years; control group: n = 58, 29 males, mean age 62 years) were available for analysis. Four patients (study group, n = 3; control group, n = 1) fulfilled the Amsterdam II criteria for hereditary nonpolyposis colorectal cancer. Of the 37 study group tumors, 12 (32.4 percent) showed high-frequency microsatellite instability, and 25 had microsatellite stability, whereas among the 58 control group tumors, 4 (7 percent) showed high-frequency microsatellite instability, and 54 had microsatellite stability (P < 0.002). Mismatch repair gene mutation analysis was performed in 12 cases (study group, n = 7; control group, n = 5). We found four mutations (MSH2 119delG, MLH1 ex9 684insT, MSH2 Gln239Stop, and MLH1 del0.8 Kb) in the study group patients and none in the control group. Of four hereditary nonpolyposis colorectal cancer patients who underwent mismatch repair gene mutation analysis, one had a mutation. CONCLUSIONS: Early-age-at-onset colorectal cancer is significantly correlated with high-frequency microsatellite instability tumor status and is a useful criterion to identify hereditary nonpolyposis colorectal cancer patients. Moreover, when used in association with high-frequency microsatellite instability status, it is effective in selecting patients for mismatch repair gene mutation analysis.     

HNPCC大肠腺瘤及癌组织微卫星不稳定与TGFβRII表达的关系

目的观察遗传性非息肉病性大肠癌（HNPCC）和大肠腺瘤癌组织中TGFβRRII、错配修复基因（hMLH1、hMSH2、hMSH6）蛋白表达和微卫星不稳定（MSI）的关系。方法以来源于33个HNPCC家系的大肠腺瘤28例和大肠腺癌14例为观察对象，以32例散发性大肠腺瘤和24例散发性大肠癌作为对照。采用免疫组织化学技术，检测大肠腺瘤及大肠腺癌组织中TGFβRRII、hMLH1、hMSH2、hMSH6蛋白表达。从活检组织中提取DNA，选择BAT-25、BAT-26、D2S123、D5S346、D17S250五个微卫星位点行荧光标记聚合酶链反应（PCR），以GeneMapper软件分析PCR产物。通过与正常黏膜微卫星序列PCR片断长度进行比较，判定腺瘤和癌组织的MSI情况。结果64．29％的HNPCC大肠腺瘤和71．43％的HNPCC大肠癌表现为MSI—H，明显高于散发性大肠腺瘤9．38％和散发性大肠癌12，5％。分别有67．86％的HNPCC大肠腺瘤和71.43％的HNPCC大肠癌表现为MMR蛋白表达缺失。明最高于散发性大肠腺瘤3．13％和散发性大肠癌12．5％。分别有57．14％的HNPCC大肠腺瘤和78.57％的HNPCC大肠癌表现为TGFβRRII低表达，明显高于散发性大肠腺瘤9．38％和散发性大肠癌41．67％。在MSI．H的HNPCC大肠腺瘤中，TGFl3RII低表达者占77．78％，MSI—H的HNPCC大肠癌中90％出现TGFβRRII的低表达。MSI—H的散发性大肠腺瘤中TGFβRRII的低表达率为66．67％，MSI—H的散发性大肠癌TGFβRRII的低表达率为100％。结论大部分HNPCC大肠腺瘤和大肠癌出现MSI—H，大部分MSI-H大肠腺瘤和大肠癌表现为TGFβRRII低表达。MSI、MMR、TGFβRRII的检测对腺瘤癌变风险的估计具有重要意义。     

RER and LOH association with sporadic colorectal cancer in Taiwanese patients

BACKGROUND/AIMS: This association study was undertaken to determine replication error and loss of heterozygosity in colorectal tumors using a set of 10 microsatellite markers linked to APC, hMSH2, hMLH1, DCC, P53, NM23, HPC1 and MET genes as well as tumor suppressor genes on 8p22. METHODOLOGY: Thirty-nine patients diagnosed and confirmed with sporadic colorectal cancer were biopsied. Their stored frozen tissues were subsequently retrieved for simultaneous analyses of replication error and loss of heterozygosity via an automated fluorescent microsatellite assay. RESULTS: Replication error was observed in 8/39 of the cases (20.5%) and had significantly higher frequency in the patients younger than 60 yr (P = 0.049). More than one third of informative tumors showed loss of heterozygosity at P53, DCC and APC genes (57.9%, 35.3% and 33.3%, respectively). Loss of heterozygosity at TP53-Dint marker was significantly associated with survival status (P = 0.038) in which a higher frequency was observed in the patients who died from colorectal cancer. Of 22 informative tumors, 6 (27.3%) showed loss of heterozygosity at the D8S254 marker that is suspected to be near one or more tumor suppressor genes and was significantly associated with gender (P = 0.046). All 6 cases of loss of heterozygosity at D8S254 were found in male patients. The frequencies of loss of heterozygosity at the NM23, hMSH2, hMLH1 and HPC1 genes were 18.5%, 12.1%, 9.1% and 7.4%, respectively. None of the cases examined displayed loss of heterozygosity at the MET oncogene. CONCLUSIONS: Additional microsatellite markers other than those associated with colorectal cancer were used to conduct the study of genomic instability and alterations in colorectal cancer tumors. The present results for the sporadic occurrence of colorectal cancer in Taiwanese patients further extend the correlation of clinical pathology and prognosis with the analysis of replication error and loss of heterozygosity.     

Microsatellite instable double primary cancers of the colorectum and stomach exhibit less favorable outcome

AIM: To ascertain the adequacy of the microsatellite instability (MSI) as a prognostic indicator by assessing MSI status of patients with double primary gastric and colorectal cancer (DPGCC). METHODS: Sixteen patients were studied, all of whom exhibited sporadic DPGCC, and had no family history of hereditary non-polyposis colorectal cancer, according to the Amsterdam criteria. A total of 32 cancers from 16 DPGCC patients, and 216 single primary CRC, were assessed for MSI in 5 microsatellite loci, BAT25, BAT26, D2S123, D5S346, and D17S250. RESULTS: MSI was observed in 6 (37.5%) of 16 GC and 4 (25.0%) of 16 CRC. Thirty tumors (13.9%) out of 216 single primary CRC and one tumor (16.7%) out of 6 double primary CRC were found to be microsatellite unstable. Of the 6 GC with MSI in DPGCC, 5 (31.3%) were MSI-high and one (6.3%) was MSI-low. In 5 of 16 DPGCC patients, the cancer recurred in or adjacent to the anastomosis or metastasized to the kidney or lung. The MSI-high DPGCC cases were associated with a younger age of onset (47.5 years vs62.5 years), higher frequency of lymph node metastasis (100% vs 25%), and advanced Dukes stage (C, 100% vs 41.7%), as well as a higher frequency of recurrence or metastasis (100% vs 8.3%). Only recurrence or metastasis showed statistical significance by Fisher's exact test. CONCLUSION: Our data suggest that MSI may play an important role in the development of DPGCC, and that it may be used clinically as a molecular predictive marker for recurrence or late metastasis of DPGCC.     

Two subtypes in colorectal mucinous carcinoma in relation to microsatellite instability

BACKGROUND/AIMS: Although some investigators have attempted to divide colorectal mucinous adenocarcinoma into two entities, there have been few reports describing microsatellite instability of each subtype. In this study, we elucidated the clinicopathological features of subtypes in mucinous carcinoma, especially the relationship between microsatellite instability and each subtype. METHODOLOGY: The present study included 33 patients with mucinous colorectal cancer. The 33 patients were classified into two groups; the papillotubular type group (n = 22) and the mucocellular type group (n = 11). The clinicopathological aspects and microsatellite instability were examined. RESULTS: Significant differences were found between the papillotubular type group and the mucocellular type group regarding the following findings such as lymphatic invasion, lymph node metastasis, peritoneal metastasis, and Dukes stage. The mucocellular type group had 2 cases with high-frequency microsatellite instability, 7 cases with low-frequency microsatellite instability and 2 cases with microsatellite stability. Conversely, the papillotubular type group included 12 cases with high-frequency microsatellite instability, 3 cases with low-frequency microsatellite instability and 7 cases with microsatellite stability. The ratio of cases with high-frequency microsatellite instability in the mucocellular type group (18.1%) was significantly lower than that of the papillotubular type group (54.5%) (P = 0.0463). The 5-year survival rate of the mucocellular type group (29.1%) was significantly lower than that of the papillotubular type group (70.3%) (P = 0.0282). CONCLUSIONS: Colorectal mucinous carcinoma needs to be classified into two groups, papillotubular type and mucocellular type, because of significant differences in microsatellite instability and patients' survival.     

Evaluation of tumor microsatellite instability using five quasimonomorphic mononucleotide repeats and pentaplex PCR

BACKGROUND & AIMS: The microsatellite instability (MSI) phenotype is a characteristic of the hereditary nonpolyposis colorectal cancer syndrome as well as approximately 15% of sporadic colon and gastric tumors. It is a valuable diagnostic marker for the identification of hereditary nonpolyposis colorectal cancer cases and may be a molecular predictive marker for the identification of colon cancer patients who benefit from chemotherapy. To evaluate MSI, a reference panel was proposed at an international consensus meeting, comprised of 2 mononucleotide (BAT-25, BAT-26) and 3 dinucleotide repeats. Analysis of BAT-26 is sufficient for detecting the MSI phenotype in most, but not all, cases. Additional results with dinucleotide markers can sometimes lead to incorrect classification of MSI tumors. METHODS: We describe here a single fluorescent multiplex system comprising 5 quasimonomorphic mononucleotide repeats for the detection of MSI tumors. RESULTS: None of 184 germline DNA samples, including 56 from African subjects, was found to contain allelic size variations in more than 2 of these markers. In contrast, all MSI tumors showed allelic size variations in 3 or more of the microsatellites. Using this assay, we confirmed (or reclassified in 6 cases) the MSI status of 124 colon and 50 gastric primary tumors and 16 colon cell lines. CONCLUSIONS: We propose that using a pentaplex polymerase chain reaction system allows accurate evaluation of tumor MSI status of DNA with 100% sensitivity and specificity without the need to match normal DNA. This assay is simpler to use than those involving dinucleotides and is more specific than using BAT-26 alone.     

Novel <Emphasis Type="Italic">hMSH</Emphasis>2, <Emphasis Type="Italic">hMSH</Emphasis>6 and <Emphasis Type="Italic">hMLH</Emphasis>1 gene mutations and microsatellite instability in sporadic colorectal cancer

Purpose To detect the hMSH2, hMSH6 and hMLH1 DNA mismatch repair gene mutations and microsatellite instability in somatic colorectal cancer.Patients and methods The mutations of hMSH2, hMSH6, and hMLH1 genes, including microsatellite instability of BAT-26, BAT-40, D2S123, D5S346 and D17S250 were analyzed in 31 patients with colorectal.Results The results revealed that eight cases (25.8%) harbored mutations in DNA mismatch repair genes. Of these, five novel mutations including I237V in exon 4 of hMSH2, ins T at codon 1196 in exon 7 of hMSH6, and ins G at codon 154 in exon 6, N158H in exon 6, and del A at codon 257 in exon 9 of hMLH1 were identified. Moreover, several intronic polymorphisms, including c–g transversion at IVS-1 nt211 + 9 of hMSH2, del T in poly T track at IVS-6 nt3559-5, ATCT duplicate in IVS-7 nt 3642 + 35 and t–g transversion at IVS-10 nt4080 + 185 of hMSH6 were demonstrated in these patients. In addition, seven cases (22.5%) exhibited microsatellite instability (MSI).Conclusion These results suggested that the inactivation of DNA mismatch repair genes and microsatellite instability may play a minor role in somatic colorectal cancer development.     

Alterations of BAT-26 identify a subset of gastric cancer with distinct clinicopathologic features and better postoperative prognosis

BACKGROUND/AIMS: Gastrointestinal tumors with microsatellite instability represent a replication error-positive phenotype. BAT-26, a repeat of 26 deoxyadenosine localized in intron 5 of hMSH2 gene, has been reported as a reliable indicator of replication error phenotype in colorectal cancers. This study investigated whether BAT-26 is a useful marker for a mutator phenotype with distinct clinicopathologic features in gastric cancer. METHODOLOGY: One hundred and nineteen gastric cancer tissues and matched non-tumor tissue were examined by polymerase chain reactions with electrophoresis for 9 dinucleotide microsatellites and BAT-26, and frameshift mutations of transforming growth factor-beta type II receptor. The relation between BAT-26 alterations and relevant clinicopathological or genetic parameters were analyzed. RESULTS: Gastric cancer with BAT-26 alterations was highly correlated with multiple microsatellite alterations (> or = 3 loci) and frameshift mutations of transforming growth factor-beta type II receptor, and predominantly showed antral location, intestinal histologic subtype, advanced stage, a higher rate of Helicobacter pylori infection, a better postoperative survival and less lymph node metastasis. CONCLUSIONS: These results show testing of BAT-26 alterations is a convenient and rapid screening method for identifying a subset of gastric cancer with a mutator phenotype and better prognosis.     

Microsatellite instability in sporadic and inherited colon adenocarcinomas from Greek patients: correlation with several clinicopathological characteristics

BACKGROUND AND AIMS: Microsatellite instability seems to play a significant role in colorectal carcinogenesis, as it is reported to occur in HNPCC patients as well as in a proportion of sporadic cases. The aim of this study was to examine the presence of microsatellite instability in relation to other commonly observed genetic abnormalities and clinicopathological characteristics of sporadic and inherited colorectal cancers. METHODOLOGY: One hundred and three sporadic colorectal adenocarcinomas and 9 adenocarcinomas from HNPCC patients were histologically evaluated. The presence of microsatellite instability was investigated at six loci. K-ras and p53 mutations, p53 LOH, hMLH1 expression and methylation status were examined as well. Statistical analysis was performed to define possible correlations of the observed genetic alterations with the clinicopathological characteristics of the analysed tumors. RESULTS: High-grade microsatellite instability was found in 14% of sporadic adenocarcinomas and in 78% of adenocarcinomas from HNPCC patients. K-ras and p53 mutations were found in 29% and 28% of sporadic adenocarcinomas respectively and in 0% and 22% of the 9 HNPCC cases. A statistically significant correlation was noticed in sporadic tumors between the presence of MSI-H and tumor location at the proximal colon, as well as with the female gender. CONCLUSIONS: Sporadic MSI+ colon adenocarcinomas seem to represent a distinct entity with a unique profile of genetic changes, different from those observed in HNPCC or MSI negative sporadic tumors.