大肠癌组织APC／MCC和DCC基因杂合缺失的研究

为评估ＡＰＣ／ＭＣＣ和ＤＣＣ基因在大肠癌发生和发展中的作用，采用聚合酶链反应（ＰＣＲ）技术，并配合限制性片段长度多态现象（ＲＦＬＰ）分析，对４１例大肠癌患者的组织ＡＰＣ／ＭＣＣ（位于染色体５ｑ２１）和ＤＣＣ基因（位于染色体１８ｑ２１．３）杂合缺失（ＬＯＨ）进行研究。ＡＰＣ基因ＬＯＨ率为２８．０％（７／２５），ＭＣＣ基因ＬＯＨ率为３６．４％（８／２２），两者综合分析ＬＯＨ率为３８．９％（１４／３８）。ＤＣＣ基因ＬＯＨ率为５５．３％（２１／３８）。ＤＣＣ基因在有淋巴结转移组的ＬＯＨ率（８０．０％）显著高于无淋巴结转移组（３９．１％）（Ｐ＜０．０５），在ＤｕｋｅｓＣ、Ｄ期组的ＬＯＨ率（７１．４％）显著高于Ａ、Ｂ期组（３５．３％）。以上结果提示，ＡＰＣ／ＭＣＣ和ＤＣＣ基因的ＬＯＨ是大肠癌常见的基因改变，ＤＣＣ基因ＬＯＨ的测定有可能成为大肠癌病人预后估计的指标。     

胃癌组织5q微卫星不稳定性与APC/MCC基因杂合性缺失的研究

目的探讨５ｑ微卫星不稳定性（ＭＳＩ）与ＡＰＣ／ＭＣＣ基因杂合缺失（ＬＯＨ）的关系。方法应用ＰＣＲ－ＳＳＬＰ及ＰＣＲ－ＲＦＬＰ技术分析５２例手术切除胃癌组织中ＭＳＩ及ＡＰＣ／ＭＭＣ基因ＬＯＨ。结果５ｑＭＳＩ检出率为３４．０％（１６／４７）,ＡＰＣ／ＭＣＣ基因ＬＯＨ率为３１．４％（１１／３５）。早期胃癌５ｑＭＳＩ阳性率为６６．７％（２／３）,ＡＰＣ／ＭＣＣＬＯＨ率为５０％（１／２）;进展期分别为３１．８（１４／４４）,３０．３％（１０／３３）。两组间无显著差别（Ｐ＞０．０５）。ＭＳＩ及杂合缺失与肿瘤大小、浸润深度、淋巴结转移及临床分期无关。粘液（印戒）细胞癌ＡＰＣ／ＭＣＣＬＯＨ率（５５．６％）显著高于高、中分化管状腺癌（Ｐ＜０．０５）。胃、肠两型胃癌５ｑＭＳＩ及ＡＰＣ／ＭＣＣＬＯＨ差异无显著性及５ｑＭＳＩ与ＡＰＣ／ＭＣＣＬＯＨ无相关性（Ｐ＞０．０５）。结论染色体５ｑＭＳＩ有ＡＰＣ／ＭＣＣ基因ＬＯＨ在两型胃癌的早期发生及发展中起一定作用。染色体５ｑ可能是胃癌的易感部位。     

大肠癌APC基因研究进展

肿瘤的发生发展除了与饮食、环境等因素有关外，还与多个癌基因的激活和肿瘤抑制基因的失活有关。结直肠癌的发生发展为肿瘤分子生物学的研究提供了极好的模式。遗传性结直肠癌包括家族性腺瘤性息肉病结直肠癌及遗传性非息肉性结直肠癌，总发病率约占结直肠癌的15％左右。遗传性结直肠癌的基因定位是近年来结直肠癌分子生物学研究的重大进展，对预防、早期诊断、早期治疗及术后随访具有重大意义。本复习近年来发现的家族性腺瘤性息肉病基因改变的一些献，并就它与结直肠癌的关系做一综述。     

结直肠肿瘤中APC基因的研究进展及临床应用展望

APC基因为结直肠腺瘤性息肉的易惑基因,定位于人体5号染色体5q21之上,由15个外显子组成,编码2843个氨基酸的蛋白(分子量约300 kDa)。APC基因的突变不仅与家族性腺瘤性息肉(FAP)有关,而且同部分散发性结直肠肿瘤有关。APC基因的突变在结直肠肿瘤的发生早期起重要作用。本文对APC基因的发现、定位及作用扼要介绍,并探讨APC基因突变在结直肠肿瘤临床应用方面的展望。     

结直肠肿瘤中APC基因突变研究进展

APC基因为结直肠腺瘤性息肉的易感基因，定位于人体5号染色体5q21上。APC基因不仅与家族性腺瘤性息肉病（FAP）有关，而且同部分散发性结直肠肿瘤也有关。本文对APC基因突变类型、功能、基因型-表型相关性、检测及临床应用作一扼要介绍。     

原发肝细胞癌N—ras基因突变,APC和DCC基因杂合缺失研究

目的 了解Ｎ－ｒａｓ基因突变。ＡＰＣ和ＤＣＣ基因杂合性缺失在原发性肝癌发生发展中的作用，方法 采用聚合酶链反应－限制性片段长度多态观察（ＰＣＲ－ＲＦＬＰ）分析技术，对３０例外科手术切除原发肝细胞癌组织中癌基因Ｎ－ｒａｓ第１２位密码子突变，抑癌基因ＡＰＣ和ＤＣＣ杂合缺失（ＬＯＨ）进行研究。结果 原发肝癌中Ｎ－ｒａｓ第１２位密码子的突变率为１６．７％（５／３０），ＡＰＣ和ＤＣＣ基因ＬＯＨ率分别为３６．     

非同位素PCR—SSCP检测结,直肠癌组织MCC突变

目的探讨中国人结，直肠癌与ＭＣＣ突变的关系。因为，结，直肠癌的发生与发展与抑癌基因的变化密切相关，包括等位基因缺失，突变，插入，染色体重排等。方法应用非同位素ＰＣＲ－ＳＳＣＰ检测４５例中国人结，直肠癌ＭＣＣ突变。结果４５例患者中，ＭＣＣ突变１３例，占２８．９％，其中高分化腺癌５／１５例，中分化腺癌６／１８例，低分化腺癌２／１２例，Ｄｕｋｅｓ分期与ＭＣＣ突变的关系：Ａ组５／１５例，Ｂ期２／１６例，Ｃ     

抑癌基因DCC和MCC在大肠癌中的变化

为了探讨ＤＣＣ和ＭＣＣ在中国人大肠腺瘤和大肠癌中的变化及其与大肠腺癌的分级、分期和大肠腺瘤的分级之间的关系，对３０例大肠腺瘤和３３例大肠癌患者用Ｓｏｕｔｈｅｒｎ杂交法检测了ＤＣＣ基因的突变和用聚合酶链反应（ＰＣＲ）方法检测了ＭＣＣ的杂合缺失（ＬＯＨ）。结果为：在大肠腺瘤患者中，仅在重度不典型增生者中能检出ＤＣＣ的突变；在３３例大肠癌中检出７例突变，且随分化的减少和分期的增加而有频度增加的趋势。３０例腺瘤中有９例检出有ＭＣＣ的ＬＯＨ，其中轻、中、重度不典型增生者分别有２、３及４例；在３３例大肠癌中检出１８例ＭＣＣ的ＬＯＨ，且其发生的频度有明显的随分级、分期的严重而增加的趋势。结论：ＤＣＣ的变化可定位于腺瘤的中、晚期阶段；ＭＣＣ的变化可定位于正常组织与腺瘤之间，且与腺瘤至癌的演变有一定关联；以上结果支持大肠癌的发生、发展是一个多基因变化的过程这一学说。     

APC基因与胃癌

ＡＰＣ基因是近年来发现的抑癌基因，有关该基因的结构、功能及与胃癌关系的研究不断得到进展。多数研究提示，该基因与细胞增殖、分化、粘附等均有一定关系，并在胃癌的早期发生及发展中可能起重要作用。因此，研究它的结构、蛋白产物及功能、致癌机制，探讨其在胃癌中的变化规律，对于胃癌的预防、诊断和治疗均具有重要意义。     

Loss of heterozygosity at adenomatous polyposis coli,mutation in colorectal cancer and deleted in colorectal cancer genetic loci in colorectal cancers

AIM: To evaluate the role and analyze the loss of heterozygosity (LOH) of adenomatous polyposis coli (APC), mutation in colorectal cancer (MCC) and deleted in colorectal cancer (DCC) genes in the development and progression of colorectal cancers. METHODS: LOH at APC, MCC and DCC genes was examined in 41 surgically resected specimens of colorectal carcinomas by polymerase chain reaction and restriction fragment length polymorphism analysis technique. RESULTS: LOH of APC and MCC were observed in 7 of 25 (28.0%) and 8 of 22 (36.4%) of informative cases, respectively. When considered as one locus, the LOH frequency for APC/MCC was 14 of 36 (38.9%). LOH at DCC gene locus was detected in 21 of 38 (55.3%) of informative cases. No correlation was found between the LOH at APC or MCC gene and tumor histological types, size, invasion, lymph node metastasis and Dukes’ stages (P > 0.05). However, LOH rates at DCC locus in the group with lymph-node metastasis (80.0%) and in Dukes’ stages III and IV (71.4%) were significantly higher than those without lymph node metastasis (39.1%) and in Dukes’ stages I and II (35.3%) (P < 0.05). CONCLUSION: LOH at APC and/or MCC may occur more frequently in the early stages and plays a role in the initiation of colorectal cancer while LOH at DCC is frequent at late event and associated with the progression and metastasis of colorectal cancer.     

A preliminary study on the loss of heterozygosity at 17p13 in gastric and colorectal cancers

Ａｐｒｅｌｉｍｉｎａｒｙｓｔｕｄｙｏｎｔｈｅｌｏｓｓｏｆｈｅｔｅｒｏｚｙｇｏｓｉｔｙａｔ１７ｐ１３ｉｎｇａｓｔｒｉｃａｎｄｃｏｌｏｒｅｃｔａｌｃａｎｃｅｒｓＷＵＧｕｏＪｕｎ１，ＳＨＡＮＸｉａｎｇＮｉａｎ２，ＬＩＭｉｎｇＦａ２，ＳＨＩＳｈａｏＬ...     

大肠癌APC基因15外显子突变分析

目的　探讨APC基因突变在大肠癌发生中的作用及与临床病理参数和微卫星不稳 (MSl)的关系。方法　采用多重PCR、DGGE电泳和DNA测序技术检测 76例大肠癌APC基因 15外显子突变 ;采用PCR为基础的方法检测MSI。结果　 76例大肠癌中检出APC基因 15外显子突变 2 9例 ,突变率为 3 8 2 % ;APC基因突变多见于左侧大肠癌 ,但与肿瘤大小、分化程度、浸润深度和临床病理分期无显著相关。高频率微卫星不稳 (MSI H)大肠癌APC基因突变率显著低于低频率微卫星不稳 (MSI L)和微卫星稳定(MSS)大肠癌 (P <0 0 5～ 0 0 1)。结论　APC基因可能是散发型大肠癌的易感基因 ,APC基因突变在大肠癌的发生中可能参与了染色体不稳途径     

变性梯度凝胶电泳分析检测结直肠癌APC和p53基因突变

目的: 探讨APC和p53基因突变在结直肠癌中的意义.方法:采用变性梯度凝胶电泳(DGGE), DNA测序法分析15例正常人和60例散发性结直肠癌标本的APC基因15外显子和p53基因第5, 7外显子的基因突变.结果: 在结直肠癌组检出14例APC和16例p53基因突变, 测序证实其中13/14例APC发生在突变集中区域;9/16例p53基因突变位于第5外显子, 7/16例p53基因突变位于第7外显子, 2例同时检出了APC基因和p53基因突变.结论:DGGE是一种快速、简便、高效、灵敏的突变检测技术. 同时也证明APC基因突变和p53基因突变均参与了结直肠癌的发生、发展过程.     

5'-CpG island methylation of the LKB1/STK11 promoter and allelic loss at chromosome 19p13.3 in sporadic colorectal cancer

BACKGROUND: In patients with Peutz-Jeghers syndrome (PJS), causative germline mutations in the LKB1/STK11 gene on chromosome 19p13.3 have been identified. Because of the loss of heterozygosity (LOH) at 19p13.3 in hamartomas and the cancer susceptibility of patients with PJS, LKB1/STK11 is suggested to act as a tumour suppressor. However, the frequency of genetic and epigenetic inactivation of LKB1/STK11 in sporadic tumours is unclear. AIMS: To investigate the LKB1/STK11 gene for promoter hypermethylation and allelic loss in tumour specimens of patients with sporadic colorectal cancer. METHODS: DNA from 50 consecutive paraffin embedded sporadic colorectal adenocarcinomas and corresponding normal epithelium was extracted. After bisulphite treatment, specimens were analysed for methylation of the LKB1/STK11 promoter 5'-CpG island by methylation specific polymerase chain reaction (MSP). In addition, tumours were analysed for LOH of chromosome 19p13.3. In tumours exhibiting LOH, LKB1/STK11 was sequenced. RESULTS: MSP was successful in 48 of 50 tumour specimens. Of those, four (8%) demonstrated hypermethylation of the LKB1/STK11 promoter 5'-CpG island. Moreover, LOH at either D19S886 or D19S878 was observed in five of 38 (13%) informative tumours. All five tumours showing LOH at 19p13.3 were advanced and four of five were located in the left sided colon. There was no correlation between LOH and LKB1/STK11 promoter hypermethylation or somatic mutation. CONCLUSIONS: In sporadic colorectal cancer, hypermethylation of the LKB1/STK11 promoter and allelic loss at the STK 11 gene locus are rare events. LOH at 19p13.3 was associated with advanced tumour stage and left sided location but not with LKB1/STK11 promoter hypermethylation or somatic mutation.     

Loss of heterozygosity and mRNA expression at deleted in colorectal cancer gene locus in gastric cancer

AIM: To assess the effects of the deleted in colorectal cancer (DCC) gene changes on the development and progression of gastric cancer.METHODS: The loss of heterozygosity (LOH) and mRNA expression DCC gastric cancer using a PCR-based detection method.RESULTS: LOH was found in 35.3% (18/51) of the specimens, and the LOH was more frequently detected in tumors from patients with stage III or IV cancer (50.5%) than those in stages I or II (14.3%) (P < 0.05). The occurrence of LOH was not found to correlate with the histological type, tumor size, invasion depth and lymph node metastasis of gastric cancer. The mRNA expression of the DCC gene was studied in 26 of the 51 cases, of which LOE was found in 30.8% (8/26). LOE was not significantly correlated to LOH or other clinicopathological parameters.CONCLUSION: LOH and LOE of DCC gene are frequently encountered in gastric cancer, and the LOH of DCC gene is a late event associated with progression of gastric cancer.     

散发性结直肠癌染色体3q24-25区杂合性缺失的精细定位

目的探讨散发性结直肠癌3号染色体杂合性缺失,对3q24-25区进行精细定位,寻找新的结直肠癌抑癌基因。方法将3号染色体采用13个微卫星DNA标记,在3q24-25区另取6个微卫星标记对83例结直肠癌患者的肿瘤和正常组织进行PCR反应。PCR产物在ABI Prism 377自动荧光测序仪进行电泳3 h,以Genescan3.1和Genotyper 2.1软件进行基因分型。结果 3号染色体上发现了2个高频杂合缺失区即3p14区和3q24-25区,在3q24-25区界定了1个大约2 cm的跨越D3S1279位点的杂合缺失区。结论 3q24-25区存在1个精细的杂合缺失区域,该区很可能存在1个或多个与结直肠癌相关的新抑癌基因。