北方人群HNPCC微卫星不稳定性和错配修复基因突变规律研究

目的探讨中国北方人群遗传性非息肉病性结直肠癌（HNPCC）微卫星不稳定性（MSI）和错配修复（MMR）基因突变的特征。方法通过MSI检测和MMR基因种系突变检测对30个中国北方人HNPCC家系进行系统分析。结果①25个家系表现为高度微卫星不稳定（MSI-H）,1个家系为低度微卫星不稳定（MSI-L）,4个家系表现为微卫星稳定（MSS）;②在25个MSI-H家系的先证者中,检测到14种致病性种系突变（hMLH1基因突变9种,hMSH2基因突变5种）,突变类型包括框移突变、无义突变、剪接区突变、错义突变,并发现3种新突变位点。结论中国北方人群HNPCC的错配修复基因突变谱广泛而多样,应开展系统研究,以建立北方人群的HNPCC错配修复基因突变库并制定相应的突变检测策略。     

Germline mutation analysis of hPMS2 gene in Chinese families with hereditary nonpolyposis colorectal cancer

AIM: To study the germline mutation of hPMS2 gene in 26 unrelated Chinese hereditary nonpolyposis colorectal cancer (HNPCC) probands and to fulfill the screening strategy for HNPCC in Chinese. METHODS: Genomic DNA was extracted from the peripheral blood. To avoid the interference of pseudogene in detection of the remaining 11 exons (exon 1-5, 9, 11-15), long-range polymerase chain reaction (PCR) was conducted to amplify the complete coding region of hPMS2 gene firstly. Then 1/8 of the PCR productswere used as template to amplify the individual exon respectively and DNA sequencing was done. Direct DNA sequencing of the conventional PCR products of exon 6, 7, 8 and 10 of hPMS2 gene was performed. The same analysis was made in 130 healthy persons without family histories of HNPCC to further investigate the pathological effects of the detected missense mutation. RESULTS: One HNPCC proband fulf illed Bethesda guidelines and was found to carry the germline mutation of hPMS2 gene, which has not been reported in Chinese HNPCC families. It was a missense mutation at c.1532C>T of exon 11. It was detected in three controls as well with an occurrence rate of 2.3% (3/130). Since it could not be found in the PMS2-single nucleotide polymorphism (SNP) database, this missense mutation is a new SNP unreported up to date. Meanwhile, 260 reported SNPs of hPMS2 gene were detected in the 26 HNPCC probands. The 2nd and 5th exons were probably the hot SNP regions of hPMS2 gene in Chinese HNPCC families involving 53.1% of all reported SNP. CONCLUSION: The germline mutation of hPMS2 gene may be rare in Chinese HNPCC families. The 2nd and 5th exons are hot SNP regions of hPMS2 gene.     

Clinical implications of multiple colorectal carcinomas in hereditary nonpolyposis colorectal carcinoma

PURPOSE: An increased incidence of multiple (synchronous and metachronous) colorectal carcinomas has been reported in hereditary nonpolyposis colorectal cancer. This review was undertaken to determine the clinical implications of multiple colorectal carcinomas in hereditary nonpolyposis colorectal cancer. METHODS: A retrospective review of the records of patients in the hereditary nonpolyposis colorectal cancer registry at Roswell Park Cancer Institute who had either synchronous or metachronous colorectal carcinomas was conducted. RESULTS: Twenty-five of 93 patients with documented pathology were found to have multiple colorectal carcinomas. The mean age at diagnosis of the index colorectal carcinoma was 46.7 (range, 28–65) years. There were 7 (7.5 percent) patients with synchronous colorectal carcinomas and 20 (21.5 percent) patients with metachronous colorectal carcinomas. Two of the seven (28.6 percent) patients with synchronous colorectal carcinomas developed a metachronous colorectal carcinoma. In the patients with metachronous colorectal carcinomas, 29 metachronous events were noted: colon (23) and rectum (6). The mean and median time interval for metachronous colorectal carcinomas were 10.9 and 11.8 (range, 1.5–43.8) years, respectively. The mean times to first, second, and third events were 11.7 (range, 1.5–43.5), 7.9 (range, 2.7–18.7), and 12.3 (range, 11.8–12.7) years, respectively. The majority of patients with metachronous colorectal carcinomas did not have stage progression at the diagnosis of the metachronous colorectal carcinomas: 13 patients had lower or same stage at first event, 4 had lower or same stage at second event, and 2 patients had lower stage at third event. Three of 20 patients with metachronous colorectal carcinomas died of their disease. CONCLUSION: Multiple colorectal cancers are common in hereditary nonpolyposis colorectal cancer. Even though stage progression may not be evident at diagnosis of metachronous colorectal cancer, some of these patients will nevertheless die of their disease.Presented at the annual meeting of the Southeastern Surgical Congress, Atlanta, Georgia, February 2 to 4, 1998.     

KRAS and BRAF gene mutations and DNA mismatch repair status in Chinese colorectal carcinoma patients

AIM:To investigate gene mutations and DNA mismatch repair(MMR) protein abnormality in Chinese colorectalcarcinoma(CRC) patients and their correlations with clinicopathologic features.METHODS:Clinical and pathological information for 535 patients including 538 tumors was reviewed and recorded.Mutation analyses for exon 2 of KRAS gene and exon 15 of BRAF gene were performed by Sanger sequencing except that in 9 tumors amplification refractory mutation system PCR was used.Expression of MMR proteins including MHL1,MSH2,MSH6 and PMS2 was evaluated by immunohistochemistry.Correlations of KRAS and BRAF mutation status and the expression status of MMR proteins with age,gender,cancer stage,location,and histology were analyzed.Correlations between KRAS or BRAF mutations and MMR protein expression were also explored.RESULTS:The overall frequencies of KRAS and BRAF mutations were 37.9% and 4.4%,respectively.KRAS mutations were more common in patients ≥ 50 years old(39.8% vs 22% in patients 50 years old,P 0.05).The frequencies of BRAF mutants were higher in tumors from females(6.6% vs males 2.8%,P 0.05),located in the right colon(9.6% vs 2.1% in the left colon,1.8% in the rectum,P 0.01),with mucinous differentiation(9.8% vs 2.8% without mucinous differentiation,P 0.01),or being poorly differentiated(9.5% vs 3.4% well/moderately differentiated,P 0.05).MMR deficiency was strongly associated with proximal location(20.5% in the right colon vs 9.2% in the left colon and 5.1% in the rectum,P 0.001),early cancer stage(15.0% in stages Ⅰ-Ⅱ vs 7.7% in stages Ⅲ-Ⅳ,P 0.05),and mucinous differentiation(20.2% vs 9.2% without mucin,P 0.01).A higher frequency of MLH1/PMS2 loss was found in females(9.2% vs 4.4% in males,P 0.05),and MSH2/MSH6 loss tended to be seen in younger(50 years old) patients(12.0% vs 4.0% ≥ 50 years old,P 0.05).MMR deficient tumors were less likely to have KRAS mutations(18.8% vs 41.7% in MMR proficient tumors,P 0.05) and tumorswith abnormal MLH1/PMS2 tended to harbor BRAF mutations(15.4% vs 4.2% in MMR proficient tumors,P 0.05).CONCLUSION:The frequency of sporadic CRCs having BRAF mutation,MLH1 deficiency and MSI in Chinese population may be lower than that in the Western population.     

Clinical characteristics and diagnosis of patients with hereditary nonpolyposis colorectal cancer

AIM: To study the clinical characteristics of hereditary nonpolyposis colorectal cancer (HNPCC) in the Chinese population and discuss the identification and management of the patients with HNPCC. METHODS: A series of 140 patients with colorectal cancers (CRC) and HNPCC associated tumors from 30 families fulfilling the Amsterdam criteria were analyzed. RESULTS: A total of 118 patients had CRC. Average age at diagnosis of the first CRC was 45.7 years, 56.8 % and 23.4 % of the first CRC were located proximal to the splenic flexure and in the rectum respectively. Twenty-three (19.5 %) had synchronous and metachronous CRC. Twenty-seven patients were found to have extracolonic tumors. Gastric carcinoma was the most common tumor type in our series (44.4 %). CONCLUSION: The frequency of HNPCC was 2.6 % in our series of patients. The main features are an excess of early onset with a propensity to involve the proximal colon, and high frequency of multiple foci. Management and surveillance for these patients should be different from sporadic CRC. Contrary to American and European reports, gastric cancer seems more frequent than endometrial cancer in Chinese. It is necessary to formulate a new HNPCC criterion for Chinese patients.     

错配修复基因突变检测对遗传性非息肉病性结直肠癌患病风险的预测

目的 探讨错配修复(MMR)基因种系突变检测在遗传性非息肉病性结直肠癌(HNPCC)家系成员患癌风险预测中的作用.方法 对43个携带致病性突变的HNPCC家系的316名家庭成员的发病情况进行详细调查,并对结果进行统计学分析.结果 ①突变状态明确的HNPCC家系年龄大于20岁的成员共263例,其中突变携带者144例,非携带者119例;HNPCC相关恶性肿瘤的发生率分别为59.03%(85/144)和2.52%(3/119),二者差异有统计学意义(X2=93.44,P＜0.01).②在144例年龄大于20岁的突变携带者中,男、女HNPCC相关恶性肿瘤发生率分别为72.00%(54/75)和44.93%(31/69),二者差异有统计学意义(χ~2=10.89,P＜0.01).③随着年龄的增加,突变携带者发生HNPCC相关肿瘤的累计风险度逐渐增加.结论 在HNPCC家系中,MMR基因种系突变携带者为发生HNPCC相关肿瘤的高危人群,MMR基因种系突变的检测能很好地预测HNPCC相关肿瘤的发生危险.     

遗传性非息肉病性结直肠癌的临床特征与诊断原则

目的：探讨遗传性非息肉病性结直肠癌（HNPCC）的临床特点和诊断。方法：收集22个符合Amsterdam标准的HNPCC家族，分析其临床特点。结果：本组符合Amsterdam标准的HNPCC发病率为2．6％＜22个家族有恶性肿瘤患者101例，结直肠癌患者84例，发生第一个结直肠癌的平均年龄为45．7岁，位于脾曲近侧结肠和直肠的分别占58．3％和23．8％。23．8％患者发生同时或异时多原发结直肠癌。20例患者发生肠外肿瘤，以胃癌居多。结论：HNPCC具有发病年龄早，近侧结肠多见，同时和异时多原发结直肠癌发生率高的特点，诊断治疗及随访应有别于散发性结直肠癌。本组肠外肿瘤以胃癌发生率高，与国外报道不同。建立中国人的HNPCC诊断标准是必要的。     

遗传性非息肉病性结直肠癌错配修复基因MLH1启动子甲基化研究

目的了解中国人遗传性非息肉病性结直肠癌中MLH1基因启动子区CpG岛的过度甲基化现象。方法在错配修复基因微小突变检测和大片段缺失检测等实验的基础上,对47例DNA标本进行硫化处理,然后采用甲基化特异性PCR（MSP）方法检测标本中MLH1基因启动子的甲基化情况。结果47例标本中发现6例存在MLH1基因启动子过度甲基化,检出率为12.8%,其中4例表现为完全甲基化,2例表现为部分甲基化。结论MLH1基因启动子过度甲基化现象在遗传性非息肉病性结直肠癌中发生率较高,是HNPCC发病的相关因素之一。过度甲基化现象的研究有助于致癌机制的进一步探讨和揭示。     

hEXO1基因突变与中国人遗传性非息肉病性结直肠癌的相关性

DNA错配修复（MMR）基因hMLH1、hMSH2、hMSH6、hPMS2等种系突变与遗传性非息肉病性结直肠癌（HNPCC）易感性相关。hEX01能与hMSH2产生很强的相互作用，参与错配修复过程和或DNA重组。本研究采用DNA测序筛查16个中国人HNPCC和低风险HNPCC家系hEXO1基因所有13个编码外显子和1个非编码外显子及剪接区，查找突变体，分析这些变异体与家系临床表型的相关性，探讨hEXO1作为HNPCC和低风险HNPCC家系易感基因的可能性。     

遗传性非息肉病性结直肠癌家系临床病理特征分析

目的 探讨中国人遗传性非息肉病性结直肠癌(HNPCC)家系发病特点及预后.方法 收集24个符合Amsterdam标准的HNPCC家系,绘制其家系图谱、收集临床病理及随访资料,分析中国人HNPCC的发病特点及预后.结果 24个HNPCC家系中,共有肿瘤患者116例(其中先证者多原发癌16例,家系成员多原发癌9例),发病年龄19～74岁,其中结直肠癌灶120个,肠外相关肿瘤32个.在24个HNPCC家系的先证者中,患第一结直肠癌的平均年龄为42.5岁,男性多于女性,右半结肠肿瘤多于左半结肠;肿瘤分化均较好,以中分化多见,病理类型以管状腺癌多见,占45.8%(11/24);截至随访结束时,术后生存≥5年者共14例,占58.3%(14/24),其中9例超过10年,最长1例存活时间已达27年.结论 中国人HNPCC以中分化管状腺癌多见,发病年龄较轻,右半结肠癌多见.     

Clinical and genetic characteristics of Chinese hereditary nonpolyposis colorectal cancer families

AIM: To analyze the clinical characteristics of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) families and to screen the germline mutations of human mismatch repair genes hMLH1 and hMSH2 in the probands.METHODS: Thirty-one independent Chinese HNPCC families were collected in Zhejiang Province. All of them met Chinese HNPCC criteria. Clinical data about patient gender, site of colorectal cancer, age of onset, history of multiple colorectal cancer, associated extracolonic cancer were recorded. PCR and denaturing high performance liquid chromatography (DHPLC) were employed to screen the mutations. Sequencing analysis was used to find out the exact mutation site and characteristics of the samples showing abnormal DHPLC profiles.RESULTS: One hundred and thirty-six malignant neoplasms were found in 107 patients including 14 multiple cancers. One hundred and six of the 136 neoplasms (77.9%) were diagnosed as colorectal cancer, with an average age of onset at 48.57 ± 29.00 years. Gastric cancer was the most common extracolonic cancer (10.3%) in these families. Twenty-three different sequence variations in hMLH1 and hMSH2 genes were detected in these 17 families. Fifteen sequence variations were located in the exons, including 5 SNPs, 3 silent mutations, 3 missense mutations, 2 nonsense mutations and 2 frameshift mutations. The latter seven mutations seemed to be pathogenic.CONCLUSION: Germline mutations of hMLH1 and hMSH2 genes are identified in about one-third HNPCC kindreds fulfilling Chinese HNPCC criteria. Chinese HNPCC families have some particular clinical characteristics, such as a left-sided predominance, less synchronous or metachronous colorectal cancer, and frequent occurrence of gastric cancer.     

新疆地区遗传性非息肉病性大肠癌临床病理特点分析

目的探讨新疆地区遗传性非息肉病性大肠癌（HNPCC）的临床病理特点,并对中国人HNPCC诊断标准进行评价。方法新疆地区符合中国人HNPCC诊断标准的HNPCC 12家系63例（HNPCC组）,其中4家系同时符合AmsterdamⅡ标准为A组,其余为B组;随机选取同期收治的无家族遗传倾向的散发性大肠癌152例（散发组）。采用SPSS16.0软件,对HNPCC组、散发组间及HNPCC中A、B组患者的临床病理资料进行比较。结果 HNPCC组发病年龄〈50岁者23例,肿瘤位于右半结肠39例,低分化癌32例,多发癌12例,肠外恶性肿瘤22例,Dukes A期24例,黏液腺癌31例;散发组分别为26、50、38、6、5、34、43例。两组比较,P均〈0.05。HNPCC中A、B组患者临床病理特征比较,P均〉0.05。结论新疆地区HNPCC的特点是发病年龄早、右半结肠多见、病理分化差、多发癌常见,肠外恶性肿瘤发生率高;与AmsterdamⅡ标准比较,中国人HNPCC诊断标准更适用于新疆地区HNPCC的诊断。     

Small bowel carcinoma in hereditary nonpolyposis colorectal cancer

A 53-yr-old man, a member of a hereditary nonpolyposis colorectal cancer (HNPCC) family, with previous colonoscopic polypectomies, presented for persisting vomiting and marked signs of dehydration. Previous radiological and endoscopic examinations of the upper digestive tract were negative, with the exception of the presence of a duodenal adenomatous polyp. Enteroclysis led to a diagnosis of obstruction at the Treitz angle due to a moderately differentiated adenocarcinoma. Microsatellite instability was demonstrated in the DNA extracted from the tumor. The patient was the carrier of a mutation in the intron 13 of the h MLH 1 gene, one of the four mismatch repair genes known to be responsible for HNPCC.     

Treatment and follow-up strategies in hereditary nonpolyposis colorectal carcinoma

The treatment and follow-up strategies of patients with hereditary nonpolyposis colorectal carcinoma (HNPCC) were analyzed in 22 Finnish HNPCC families in systematic follow-up between 1983 and 1990. During the sevenyear study period metachronous colorectal neoplasia was diagnosed in 41 percent (15/37) of the patients treated by segmentai colonic resection and in 24 percent (4/17) of those treated by subtotal colectomy. Extracolonic carcinoma was diagnosed in 12 (30 percent) of the 40 patients during the long-term follow-up. The most common extracolonic malignancy was biliopancreatic carcinoma which accounted for all five cancer-related deaths in the whole series during the study period. It was concluded that subtotal colectomy is superior to hemicolectomy or segmental resection in HNPCC patients with colorectal carcinoma. A regular annual endoscopic follow-up of the residual rectum is still necessary, and surveillance for extracolonic cancers must be considered.This work was supported by the Finnish Cancer Society and the Foundation of Gastroenterological Research.     

Identification of mismatch repair gene mutations in young patients with colorectal cancer and in patients with multiple tumours associated with hereditary non-polyposis colorectal cancer

BACKGROUND: Patients with early-onset colorectal cancer (CRC) or those with multiple tumours associated with hereditary non-polyposis colorectal cancer (HNPCC) raise suspicion of the presence of germline DNA mismatch repair (MMR) gene mutations. AIM: To analyse the value of family history, microsatellite instability (MSI) analysis and MMR protein staining in the tumour to predict the presence of an MMR gene mutation in such patients. METHODS: In 281 patients diagnosed with CRC before the age of 50 years or with CRC and at least one additional HNPCC-associated cancer, germline mutation analysis in MLH1, MSH2 and MSH6 was carried out with denaturing gradient gel electrophoresis and multiplex ligation-dependent probe amplification. MSI analysis with five consensus markers and MMR protein staining for MLH1, MSH2 and MSH6 were carried out in the tumours. RESULTS: 25 pathogenic mutations (8 in MLH1, 9 in MSH2 and 8 in MSH6) were found. MSI analysis missed three and immunohistochemistry (IHC) missed two mutation carriers. Sensitivities of family history, MSI analysis and IHC for the presence of a mutation were 76%, 82% and 88%, specificities were 64%, 70% and 84%, and positive predictive values were 19%, 23% and 38%, respectively. Multivariate analysis showed the highest odds ratio for IHC (38.3, 95% confidence interval 9.0 to 184). Prevalence of pathogenic germline MMR gene mutations in patients with CRC before the age of 50 years was 6% and in those with > or =2 HNPCC-associated tumours was 22%. In the second group, no mutation carriers were found among the 29 patients who were diagnosed with their first tumour after the age of 60 years. CONCLUSION: Family history, MSI analysis and IHC are indicative parameters to select patients with CRC for MMR gene mutation analysis. The data show that IHC is the best single selection criterion.