Screening of tumor suppressor genes on lq31.1-32.1 in Chinese patients with sporadic colorectal cancer

Background As a model for both multistep and multipathway carcinogenesis, colorectal neoplastic progression provides paradigms for researching both oncogenes and tumor suppressor genes (TSGs). However, the mechanism of colorectal cancer (CRC) is not completely understood, and many genes may be involved in the colorectal carcinogenesis. The purpose of this study was to screen for the potential TSGs on chromosome lq31.1-32.1 in Chinese patients with sporadic colorectal cancer, to explore whether colorectal cancer in the Chinese population has unique genetic alterations and determine whether other putative TSGs exist and contribute to colon carcinogenesis. Methods Six polymorphic microsatellite markers, at a density of approximately one marker in every 1.6 cM, were chosen for refined loss of heterozygosity (LOH) mapping of lq31.1-32.1. Eighty-three colorectal cancer patients' tumor and normal DNA were analyzed via polymerase chain reaction (PCR) for these microsatellite markers. PCR products were eletrophoresed on an ABI 377 DNA sequencer. Genescan 3.1 and Genotype 2.1 software were used for LOH scanning and analysis. On the basis of refined LOH mapping results, we undertook a microarray-based expression screening to identify tumor association genes in 19 of the CRC cases. Results The average LOH frequency of lq31.1-32.1 was 24.41%, with the highest frequency of 36.73% (18/49) at D1S2622, and the lowest of 16.42% (11/67) at D1S412. A minimal region of frequent deletion was located within a 2 cM genomic segment at D1S413-D1S2622. There was no significant association between LOH of any marker in the studied regions and the clinicopathological data (patient sex, age, tumor size, growth pattern, or Dukes stage). On the basis of refined mapping results, we chose 25 genes located in the D1S413-D1S2622 (lq31.3-32.1) region and presented a microarray-based high throughput screening approach in 19 sporadic CRC cases to identify candidate CRC related tumor suppressor genes. This study found 4 significantly down-expressed genes, including CSRP1, LMOD1, PPP1R12B and CFHL3. There was no significant association between expression levels of CFHL3, CSRP1, LMOD1, PPPIR12B and the clinicopathological data. By database searching, CSRP1 was hypothesized to be a colorectal cancer related tumor suppressor gene. Conclusions Through detailed deletion mapping, we found that the lq31.3-32.1 region might harbor one or more colorectal cancer related tumor suppressor gene(s). And by microarray-based high-throughput screening of candidate genes located in this region and by subsequent database searching, we present the first evidence that CSRP1 might be involved in the progression of CRC.     

散发性结直肠癌染色体10q23～24区域杂合缺失分析

目的抑癌基因的杂合缺失（LOH）被认为是结直肠癌形成的通路之一,本实验拟通过对染色体10q23～24区的LOH分析,发现高频杂合缺失区域并筛查与结直肠癌相关的抑癌基因。方法7个荧光标记的微卫星引物（围绕D10S185位点）与83例结直肠癌的肿瘤和正常组织进行聚合酶链反应（PCR）反应。产物在ABI Prism377自动荧光测序仪进行电泳,以GeneSean3．1和Genotyper2．1软件进行扫描以及杂合缺失分析LOH。与临床病理因素之间的关系比较采用X^2检验。结果7个位点平均杂合缺失率为36．11％,以D10S583位点最高,达54．84％;最低是D10S205,21．3％。发现两个高频杂合缺失区域：一个在D10S583和D10S185之间,大约0．9cM（10q23．33）的距离;另一个在D10S1709和D10S1265位点之间,大约1．5cM（10q24．2～24．31）的距离。D10S1265位点的杂合缺失与Dukes分期显著相关,其余位点与临床病理因素均无显著相关。结论在散发性结直肠癌10q23-24发现了两个高频LOH区域：10q23．33和10q24．2～24．31。除对磷脂酶同族蛋白（PTEN）基因外,10q上可能存在与散发性结直肠癌相关的其他抑癌基因。     

胃癌染色体1q21等位基因杂合性缺失的精细定位

目的 精细定位胃癌染色体1q21等位基因杂合性缺失及其常见缺失区域,并初步探讨1q21等位基因杂合性缺失在胃癌发生发展中的作用.方法 采用1q21区域7个高密度微卫星多态性标志结合PCR技术.精细分析了30例配对新鲜胃癌手术标本中胃癌染色体等位基因杂合性缺失的情况,利用X2检验和四格表确切概率法初步探讨了1q21等位基因杂合性缺失与胃癌临床特征的关系.结果 30例胃癌标本中,有18例存在等位基因杂合性缺失,占60%(18/30),7个微卫星位点D1S514、D1S2696、D1S498、D1S305、D1S2624、D1S2635和D1S2707的杂合性缺失频率分别为13.3%、10%、20%、23.3%、33.3%、40%和23.3%.常见高频率杂合性缺失区域位于D1S2624-D1S2707之间,即共同缺失区在D1S2635附近;胃癌染色体1q21等位基因杂合性缺失与病人的年龄、性别、胃癌原发灶的部位、癌细胞分化程度及临床分期比较差异没有湿著性意义(P>0.05);但是,胃癌染色体1q21等位基因杂合性缺失与胃癌有无淋巴结转移比较差异有显著性意义(P<0.05).结论 胃癌细胞染色体1q21存在较高频率的等位基因杂合性缺失,D1S2635附近可能存在与胃癌发生密切相关的肿瘤抑制基因.     

散发性结直肠癌1p36.33-36.31区域等位基因杂合缺失精细定位

目的抑癌基因的杂合缺失（LOH）被认为是结直肠癌形成的通路之一,本实验通过对染色体1p36．33-36．31区域的杂合缺失精细定位分析,发现高频杂合缺失区域并探讨其意义。方法7个荧光标记的微卫星引物（1p36．33-36．31）与83例结直肠癌的肿瘤和正常组织进行聚合酶链反应（PCR）。产物在ABI Prism377自动荧光测序仪进行电泳,以GeneSean3．1和Genotyper2．1软件进行扫描以及杂合缺失分析。杂合缺失结果与临床病理参数之间的关系比较采用χ^2检验。结果1p36．33-36．31区域平均杂合缺失率是31．5％,以D1S243位点最高,47．2％,最低是D1S1347,7．4％。存在两个高频杂合缺失区域：D1S243位点（1p36．33）以及D1S468和D1S2660位点之间约3cM的区域（1p36．32-36．31）。1p36．33—36．31区域各位点的杂合缺失率与性别、年龄、肿瘤大小生长方式以及分级无显著相关。结论1p36．33-36．31区域发现了两个高频LOH区域：1p36．33和1p36．32-36．31,可能存在与结直肠癌发生相关的抑癌基因。     

Loss of heterozygosity of chromosome 20 in sporadic colorectal cancer

Objective To analyze the loss of heterozygosity (LOH) of chromosome 20 in patients with sporadic colorectal cancer to identify additional loci involved in colorectal tumorigenesis. Methods Polymorphic microsatellite markers were analyzed in 83 colorectal cancer patients’ tumor and normal DNA by PCR. PCR products were electrophoresed on an 377 DNA sequencer. Genescan 2. 1 and Genotype 2. 1 software were used in the LOH scanning and analysis. Comparisons between LOH frequency and clinicopathological data were performed by Χ(2) test.P&lt;0. 05 was considered statistically significant. Results The average LOH frequency in the long arm, short arm and whole chromosome 20 was 21. 1%, 26. 7% and 22. 8%, respectively. Chromosome 20 exhibited relatively high LOH frequency, particularly in the regions of 20p and 20q11. 1-q13. 1.Conclusion There is notable genetic instability on chromosome 20 in sporadic colorectal carcinoma patients; that is, mutation on chromosome 20 is closely associated with sporadic colorectal carcinogenesis. Also, there may be tumor suppressor genes related to sporadic colorectal carcinoma near the region 20q11. 1-q13. 1.     

胶质母细胞瘤染色体13q上肿瘤抑制基因存在的可能性

目的寻找胶质母细胞瘤(glioblastoma,GBM)13号染色体上可能存在肿瘤抑制基因的杂合性丢失 (LOH)区域,为发现和定位肿瘤抑制基因(TSG)提供线索和依据。方法应用聚合酶链反应(PCR)方法,采用 荧光标记的引物和377型DNA序列自动分析仪,分析了20例GBM13号染色体上14个微卫星多态性标记的 LOH。结果在60％GBM的13号染色体上观察到LOH,在45.8％可提供信息位点存在LOH。其中13q的 LOH率明显高于13p,13q和13p的LOH率分别为60％、27％。在13q上的下列位点上检测到较高的LOH率 (＞50％)13q14.1-14.3上D13S153,13q12-14.2上的D13S217-D13S263,13q21.2-32上的D13S156-D13S265。 结论13号染色体可能在GBM的分子发病机制中发挥着重要作用,在13q14.1-14.3上的D13S153位点、13q 12-14.2上的D13S217-D13S263和13q21.2-32上的D13S156-D13S265间区域可能存在多个与GBM相关的肿瘤 抑制基因,可能包括RB1以及不同于RB1的其他肿瘤抑制基因。     

子宫内膜癌患者FHIT、SLIT2、EDNRB基因杂合性丢失

目的：探讨子宫内膜癌患者FHIT、SLIT2、EDNRB基因3个微卫星位点D3S1287、 D4S1593、D13S160杂合性丢失（loss of heterozygosity，LOH），以确定侯选的抑癌基因。方法：应用PCR-变性 PAGE-银染方法分别对35例子宫内膜癌患者癌组织及相对应的正常子宫内膜组织在FHIT、SLIT2、EDNRB基因3个微卫星位点D3S1287、D4S1593、D13S160 行LOH检测。结果：LOH总检出率为54.3%，D3S1287、D4S1593、D13S160位点分别为34.5%、20.5%、19.3%。FHIT、SLIT2、EDNRB基因的3个微卫星位点发生LOH率与子宫内膜癌手术-病理分期无明显相关性。结论：子宫内膜癌患者肿瘤组织在FHIT、SLIT2、及EDNRB基因的微卫星位点D3S1287、D4S1593、D13S160 均有LOH。FHIT、SLIT2及EDNRB基因为抑癌基因，其失活可能与子宫内膜癌的发生有关。     

Colorectal carcinogenesis.

Colorectal carcinogenesis is a multi-step process during which genetic and epigenetic events determine the transition from a normal cell to a malignant cell. In the past decade, intensive research led to the identification of two types of colorectal cancers that are distinct by their carcinogenesis process. The first group, named LOH (Loss of Heterozygosity) type, is characterized by allelic losses of tumor suppressor genes. The second group, called MSI (Microsatellite Instability) type, is characterized by genetic instability at microsatellite loci. In addition, recent studies suggest the four different signaling pathways, Wnt/Wingless pathway, K-ras pathway, TGF-beta pathway and p53 pathway, could be implicated in tumor progression. In this review we discuss the development of colorectal cancer on the basis of molecular biology and recent advances in research of the colorectal cancer.     

肺癌组织3号染色体短臂上抑癌基因异常改变的初步分析

目的 探讨3号染色体短臂上的抑制基因Fhit,hMLH1及VHL在肺癌发展中的可能作用。方法 选取上述基因内含子或附近的微卫星多态位点对45例肺癌组织进行杂合性缺失（LOH）分析,并对其中17例进行了Fhit蛋白的免疫组化染色。结果 Fhit基因内含子3个位点D3S1234、D3S1300及D3S4103的杂合率分别为77．8％（35／45）、73．3％（33／45）和82．2％（37／45）,LOH阳性率分别为62．9％（22／35）、63．6％（21／33）和59．5％（22／37）。与hMLH1基因连锁的两个位点D3S1561、D3S1612杂合率分别为48．9％（22／45）、42．2％（19／45）,LOH阳性率分别为54．5％（12／22）和63．2％（12／19）。与VHL基因连锁的两个位点D3S1038、D3S1283的杂合率分别为62．2％（28／45）和80．0％（36／45）,LOH阳性率分别为64．3％（18／28）和41．7％（15／36）。17例肺癌组织有64．7％（11／17）Fhit蛋白表达缺失。在Fhit蛋白缺失的11个病例中,有10例存在一个或多个Fhit基因位点的LOH。结论 上述3个抑癌基因存在的高频率LOH可为肺癌的早期诊断提供新的途径和依据。Fhit基因的杂合性缺失可能是Fhit蛋白表达下调的机理之一。     

散发性结直肠癌3号染色体等位基因杂合缺失

目的 了解散发性结直肠癌（SCRC）3号染色体等位基因杂合缺失（LOH）发生情况。探讨其与临床病理特征间的关系,并对3号染色体上可能的SCRC相关基因进行初步定位。方法 用覆盖3号染色体的13个微卫星标记对83例散发性结直肠癌进行LOH扫描分析。结果 3号染色体至少有两个位点发生LOH者占39%（29/74）,3p所选4个位点中至少有一个发生LOH者占37%（27/74）,3q所选9个位点中至少有一个发生LOH者占53%（39/74）。整条染色体上以D3S1300（3q14.2)位点LOH率最高,达54%（23/43）。3qLOH在远端结直肠癌较近端高发,3q及D3S1300LOH阳性肿瘤多表现为浸润型生长和局部侵犯,并多发于大于50岁的老年患者。结论 3号染色体存在散在分布及区域性高频等位基因LOH,并与SCRC临床病理资料相关,提示其上SCRC相关基因的存在。高频LOH位点D3S1300的发现,提示3p14.2附近区域的FHIT基因可能作为肿瘤抑制基因在结直肠癌的发生发展中发挥作用。     

Chromosome 6q deletion mapping in human ovarian tumor, a common deletion region between D6S1649 and D6S311

Objective： To explore the loss of heterozygosity（LOH） on chromosome 6q in ovarian cancer, and localize a minimum area in deletion region. Methods： 93 ovarian tumors were analyzed for LOH studies with 10 microsatellite markers spanning chromosome 6q. To further localize a minimum area in deletion region. Nineteen microsatellite markers were used to refined a minimum area. Results： Forty three tumors （46%） were demonstrated allelic losses, which spanned less than two megabase areas, franked by a distal marker D6S311 and a proximal marker D6S1649, and likely harbored ovarian tumor suppressor gene （s）. With analysis of density of LOH, increased DNA copy number at loci of 6q was demonstrated between D6S1649 and D6S311. Conclusion： It is possible that duplication after the allelic loss might be a main mechanism that leads to carcinogenesis in ovarian tumor. The refinement of these candidate tumor suppressor genes loci might facilitate future loss of heterozygosity studies and enable the isolation of candidate genes from this region.     

膀胱移行细胞癌3号染色体短臂上抑癌基因杂合性缺失的研究

目的 探讨位于3号染色体短臂的候选抑癌基因FHIT、hMLH和VHL在中国人膀胱移行细胞癌（TCC）发生中的可能作用。方法 选取6个位于上述基因内含子或与上述基因紧密连锁的微卫星多态标记对40例膀胱TCC组织进行杂合性缺失（LOH）分析。结果 位于FHIT基因内含子内的两个微卫星多态标记（D2S1234和D3S1300）中至少有一个为杂合子的杂合率为95．0％（38／40）,至少有一个发生LOH的频率为57．8％（22／38）。与hMLH1基因连锁的两处微卫星多态标记（D3S1561和D3S1612）中至少有一个为杂合子的杂合率为55．0％（22／40）,至少有一个发生LOH的频率为59．1％（13／22）。与VHL基因连锁的两个微卫星多态标记（D3S1038和D3S1284）中至少有一个为杂合子的杂合率为90．0％（36／40）,至少有一个发生LOH的频率为47．2％（17／36）。在所检测微卫星多态标记中仅D3S1284的LOH与膀胱TCC的病理分期正相关（P＜0．01）,余微卫星多态标记的LOH与膀胱移行细胞癌病理分级及病理分期均不相关（P＞0．05）。结论 上述3个基因在膀胱TCC中存在高频率LOH,提示它们可能在膀胱TCC的发生发展中起重要作用。FHIT基因和hMLH1基因的缺失作为分子标志有可能为膀胱TCC的早期诊断提供新的途径和依据,而VHL基因的缺失可能是膀胱TCC发生的晚期事件。     

中国人胃癌染色体11p15.5处杂合性缺失分析

目的　通过对中国人胃癌染色体 11p15 .5处杂合性缺失的研究 ,了解中国人群中胃癌病人在此区域杂合性缺失的情况。方法　从 66例胃癌病人的石蜡包埋的手术病理标本中 ,提取肿瘤及相应正常组织的DNA ,用荧光标记的方法选取 11p15 .5处的微卫星DNA标记进行PCR扩增 ,再将PCR产物进行变性聚丙烯酰胺凝胶电泳 ,电泳后行杂合性缺失分析。结果　 11/ 3 6( 3 0 .6% )的病人在D11S13 18处存在杂合性缺失 ;而D11S40 46位点处 ,13 / 60 ( 2 1.7% )的病例存在杂合性缺失 ;2 4/ 61( 3 9.3 % )的病例在 11p15 .5处至少有 1个位点存在杂合性缺失。杂合性缺失的频率与肿瘤病人的年龄、性别、肿瘤大小、肿瘤部位及淋巴结是否转移均无关。结论　高频杂合性缺失的区域可能有抑癌基因的存在。这将有助于阐明胃癌发生发展的分子机制 ,进而为对胃癌进行风险预测、基因诊断以及基因治疗提供可能     

结直肠癌中DPC4/SMAD4基因杂合性缺失及生物学意义

目的分析我国散发性结直肠癌肿瘤组织中,DPC4/SMAD4基因杂合性缺失的发生情况.方法利用D18S46、D18S363、D18S474、D18S535和D18S877共5个跨DPC4基因区域的微卫星位点,采用微卫星分析方法,对25例散发性结直肠癌相关位点的杂合性缺失(LOH)进行了分析.结果至少1个位点呈多态性的病例为l00%,DPC4/SMAD4基因LOH发生率为60%.结论等位基因杂合性缺失是中国人散发性结直肠癌中DPC4基因失活的重要机制.     

Genome-wide allelotype study of primary glioblastoma multiforme

Objective To investigate the molecular genetic pathogenesis of primary glioblastoma multiforme (GBM) and identify which chromosomes or chromosomal regions of the entire genome may harbor tumor suppressor genes (TSGs) associated with GBM.Methods A high-resolution allelotype study of 21 cases of primary GBM was performed by PCR-based loss of heterozygosity （LOH）analysis. Three hundred and eighty-two fluorescent dye-labeled microsatellite markers covering all 22 autosomes were applied. The mean genetic distance between two flanking markers was about 10 cM.Results LOH was observed on all 39 nonacrocentric autosomal arms examined in this study. The LOH frequencies of 10q, 10p, 9p, 17p and 13q were the highest (&gt;50%). Furthermore, high LOH frequencies were detected in the regions containing known TSGs including PTEN, DMBT1, p16, p15, p53 and RB; the LOH frequencies on 14q, 3q, 22q, 11p, 9q, 19q were also high (&gt;40.5%). Our study observed the following commonly deleted regions: 9p22-23, 10p12.2-14, 10q21.3, 13q12.1-14.1, 13q14.3-31, 17p11.2-12, 17p13, 3q25.2-26.2, 11p12-13, 14q13-31, 14q32.1, 14q11.1-13, 22q13.3, 4q35, 4q31.1-31.2, 6q27 and 6q21-23.3. Conclusions The molecular pathogenesis of GBM is very complicated and associated with a variety of genetic abnormalities on many chromosomal arms. The most closely related chromosomal arms to the pathogenesis of GBM are 10q, 10p, 9p, 17p and 13q. Besides the well-known TSGs including PTEN, DMBT1, p16, p15, p53 and RB, multiple unknown TSGs associated with GBM may be present on the commonly deleted regions detected in the present study.     

Chromosome 14q may harbor multiple tumor suppressor genes in primary glioblastom a multiformec

目的：评价染色体14q的（杂合性）丢失是否与原发性多形性胶质母细胞瘤的发生发展有关,并确定14q上可能存在的共同杂合性丢失区域。方法：应用聚合酶链反应（PCR）为基础的微卫星分析方法,采用14个荧光标记的多态性（微卫星）标记,检测了20例原发性多形性胶质母细胞瘤（GBM）染色体14q的杂合性丢失（LOH）状况。结果：50％（10/20例）GBM在染色体14q上至少有一个微卫星标记存在LOH,其中5个病例的所有被检测标记都表现为LOH或不能提供信息。在位于14q32.1的D14S65位点、14q23-31的D14S63-D14S74位点间区域检测到的LOH率最高,分别为57.1％、46.7％-47.1％。在本研究中的所有位点,均未检测到微卫星不稳定。结论：染色体14q上的等位基因丢失可能在GBM发病机制中起着重要作用,14q32.1上的D14S65位点、14q23-31上的D14S63-D14S74位点间区域可能存在与GBM相关的多个肿瘤抑制基因。     

人类垂体腺瘤中的基因突变

由于人类垂体腺瘤是单克隆细胞起源，故提示基因突变在肿瘤生成中发挥着重要作用。目前发现包括生长激素腺瘤癌基因gsp的表达，癌基因p53表达异常，MEN-1缺失和P16的高甲基化等，在垂体腺瘤发生发展和侵袭性生长中发挥作用     

人膀胱移行细胞癌染色体17p13区域杂合性缺失精细作图

目的　明确染色体 17p13区域等位基因杂合性缺失 (LOH)在人膀胱移行细胞癌 (TCC)中的发生频率和最小缺失区域 ,为膀胱TCC相关抑癌基因的定位克隆提供线索。方法　应用位于17p13区域的 13个微卫星标记 ,对 4 4例膀胱TCC患者手术切除的癌组织进行LOH分析 ,并探讨各微卫星标记LOH与病理分级、分期的关系。结果　 4 4例患者中 ,35例 (79 5 % )的膀胱TCC组织中存在至少 1个微卫星标记的LOH。缺失频率最高的微卫星标记是位于 17p13 2的D17S5 13,达 4 1 4 % (12 /2 9) ;其次为位于 17p13 3的D17S130 8,为 4 0 5 % (17/ 4 2 ) ;最低为位于 17p13 1的D17S2 6 1,为 14 3% (4/2 8)。LOH主要集中于三个区域 :位于 17p13 3的D17S6 95～D17S130 8,位于 17p13 2的D17S15 33～D17S831,以及位于 17p13 1区域的TP5 3。所检测微卫星标记中仅TP5 3的LOH与膀胱TCC病理分级(χ2 =5 10 4 ,P <0 0 5 )和分期 (χ2 =5 382 ,P <0 0 5 )呈正相关。结论　在 17p13区域除TP5 3基因以外 ,还可能存在两个与膀胱TCC相关的抑癌基因 ,分别位于 17p13 3的D17S6 95～D17S130 8和17p13 2的D17S15 33～D17S831。TP5 3的LOH是膀胱TCC发展的晚期事件 ,而 17p13 3和 17p13 2区域的LOH则可能是膀胱TCC发生的早期事件     

Deletion of chromosomes 9p and 17 associated with abnormal expression of p53, p16/MTS1 and p15/MTS2 gene protein in hepatocellular carcinomas

Ｈｅｐａｔｏｃｅｌｌｕｌａｒｃａｒｃｉｎｏｍａ (ＨＣＣ)ｒａｎｋｓｔｈｉｒｄａｍｏｎｇｔｈｅｃａｕｓｅｓｏｆｃａｎｃｅｒｍｏｒｔａｌｉｔｙｉｎＣｈｉｎａ ,ａｎｄａｂｏｕｔ4 2 5%ｏｆｔｈｅｗｏｒｌｄ’ｓｎｅｗｃａｓｅｓｏｆＨＣＣｅａｃｈｙｅａｒｏｃｃｕｒｉｎＣｈｉｎａ 1ＥｐｉｄｅｍｉｏｌｏｇｉｃｓｔｕｄｉｅｓｐｒｏｖｉｄｅｅｖｉｄｅｎｃｅｔｈａｔｉｎｆｅｃｔｉｏｎｗｉｔｈｈｅｐａｔｉｔｉｓＢ (ＨＢＶ )ａｎｄ/ｏｒｈｅｐａｔｉｔｉｓＣ (ＨＣＶ ) ,ａｎｄｉｎｇｅｓｔｉｏｎｏｆａｆｌａｔｏｘｉｎＢｃｏｎ…     

用原位RT—PCR技术检测大肠癌组织中相关新基因SNC66的表达

目的：探讨在肿瘤组织石蜡切片标本中原位检测内源性基因表达产物的灵敏方法，研究大肠癌相关新基因SNC66在大肠癌组织中的表达情况以及与大肠癌的相关性。方法：经原位逆转录后进行原位PCR扩增，在扩增过程中掺入地高辛标记的核苷酸（Dig-UTP)并加以检测。比较SNC66在大肠粘膜和大肠癌组织中的表达情况。结果：25个循环时，37例大肠癌组织标本有10例阴性不表达，27例强阳性表达。10个循环时，则14例呈阴性，18例弱阳性，5例强阳性。配对的37例大肠粘膜标本则都呈强阳性表达。结论：原位RT－PCR是一种检测内源性基因低拷贝转录产物mRNA的较灵敏的方法。SNC66基因在大肠癌组织中存在明显的表达降低或缺陷，可作为侯选的抑癌基因加以进一步研究。