【作者】 张静；

【导师】 田东萍； 苏敏；

【作者基本信息】 汕头大学 ， 病理学与病理生理学， 2008， 硕士

【摘要】 背景与目的食管癌(Esophageal Cancer,EC)、贲门癌(Cardicac Cancer,CC)是世界上常见的恶性肿瘤,发病率呈地区分布不均衡现象。虽然潮汕和太行山地区环境和人们的生活方式截然不同,但两地均为我国食管癌、贲门癌高发区;遗传易感性可能在食管癌、贲门癌发病中发挥了不可忽视的作用。p53基因与多种恶性肿瘤发生、发展密切相关,其第72位密码子存在单核苷酸多态性(p53 Pro72Arg,rs1042522),表达产生两种野生型p53蛋白。该多态在不同地域、种族中分布不同,与肿瘤易感性关系研究结果存在差异。本研究分别检测潮汕、太行山两高发区病例与对照人群p53 Pro72Arg基因型,观察该多态在两高发人群中的分布特征及与其它地区、人群比较的差异;比较分析等位基因及基因型频率在病例与对照中的分布差异,初步探讨p53 Pro72Arg多态与食管癌、贲门癌遗传易感性的关联。材料与方法标本来源:选取本课题组2002年以来收集的潮汕及太行山高发区人群外周血样。病例组来自当地医院确诊为食管癌或贲门癌的患者,对照组来自两地肿瘤高危人群普查的健康人。其中潮汕病例461例、对照499例;太行山病例421例、对照500例。所有病例及对照均为籍贯在两高发区的中国汉族人。实验方法:采用UltraPureTM基因组DNA快速提取试剂盒提取基因组DNA; PCR扩增包含p53 Pro72Arg位点的基因片段;应用高通量基于凝胶基因芯片的SNP分型技术检测p53 Pro72Arg基因型并测序验证。统计分析方法:将本研究结果与文献及公共数据库数据比较;分别以地域、性别、年龄、是否吸烟、有无消化道肿瘤家族史逐一分层进行病例-对照比较。采用卡方检验比较基因型及等位基因频率;非条件logistic回归计算发病风险(用性别、年龄校正)。结果1. p53 Pro72Arg等位基因在潮汕、太行山高危人群中分布差别无统计学意义(χ2 =0.67, P=0.41),与中国其他地区汉族及壮族比较差别无统计学意义;在两高危人群总体中的分布与世界其他地区、种族人群比较,差别具有显著性;2. p53 Pro72Arg基因型在两高发区人群食管癌病例组与高危人群对照组间总体分布差异具有显著性(P=0.03)。与携带Arg/Arg比较,Pro/Arg和(Pro/Arg+Pro/Pro)可增加两高发区人群食管癌的发病风险,校正比值比(odds ratio, OR)分别为1.37和1.38,95%置信区间(confidengce interval, CI)分别为(1.04-1.80)和(1.06-1.79);携带Pro/Pro可增加较低年龄段(≤50岁)人群食管癌的发病风险,OR值为1.89(95%CI=1.03-3.45)。未发现该多态与贲门癌发病风险明显相关。结论1.中国南北两大食管癌高发区潮汕地区及太行山区人群具有相同的p53 Pro72Arg多态遗传背景;且同我国其他汉族人群及少数民族壮族一致。2.两高发区高危人群中,携带p53 Pro72Arg Pro等位基因可能与食管癌易感性有关;携带Pro/Pro基因型尤可增加较低年龄人群的食管癌发病风险。3. p53 Pro72Arg Pro/Pro有可能作为中国食管癌低年龄段高危人群易感个体筛选的遗传学标记。更多还原

【Abstract】 Background and ObjectiveEsophageal cancer (EC) and Cardiac cancer (CC) are common cancers globally with great diversity in their incidences. Chaoshan littoral and Taihang mountains both belong to the six EC&CC high risk areas in China. Although the two areas are completely different in environment and people’s lifestyle, they are almost the same in incidences, family aggregation and pathology types of EC&CC. It is a clue show the hereditary susceptibility may play an important role in the carcinogenesis of EC&CC. Tumor suppressor gene p53 has a tight relationship with almost all kinds of human malignancies. p53 gene codon72 polymorphism (p53 Pro72Arg,rs1042522) results from a single base change (from CGC to CCC). The p53 Pro72Arg polymorphism genotype distribution has geographical and ethnical diverse. Previous studies have shown its association with many kinds of human cancer, however, its significance as a genetic susceptibility factor of cancer is still a matter of controversy. We detecte p53 Pro72Arg polymorphism genotype on cases and controls from Chaoshan littoral and Taihang mountains, observe the distribution of p53 Pro72Arg polymorphism genotype in the two high risk populations and compare our results with other population from other races or areas in the world and other areas in China using references and public data. And we also compare the results of cases with controls in order to investigate the relationship between Pro72Arg polymorphism and EC& CC susceptibility in the two high incidence areas.Materials and MethodsSample Resources: Peripheral blood samples from Chaoshan and Taihang had been collected by our group since 2002. Cases were the EC or CC patients from hospitals of these two areas including 461 samples from Chaoshan and 421 samples from Taihang. Controls were the healthy subjects who took part in the survey of EC high risk group in these two areas, including 499 samples from Chaoshan and 500 samples from Taihang. All the samples were Chinese Han nationality with their native place in these two high risk areas.Experiment Methods: Genomic DNA was extracted from peripheral blood leukocytes using the UltraPureTM DNA extraction kit (Beijing SBS Genetech C0.,Ltd.); PCR was conducted to amplificate DNA squencece including p53 codon 72. Primers were designed by Primer Primier 5.0 software. The genotypes were evaluated separately by DNA microarray using a method called gel-based microarray for SNP genotyping and a verification of sample drawing DNA sequencing was followed.Statistic Methods: Other data from references and public data were collected for comparing with our results. Area, sex, age, smoking habit and digestive tract tumor family history are used as layers in case-control study. Chi square test was used for the comparison of the frequencies of genotypes and alleles. Unconditional logistic regression was used to evaluate the risk of EC or CC (adjusted by sex and age).Results1. The p53 Pro72Arg allele frequence distribution in our control populations was identical(χ2 =0.67, P=0.41). When compared with other normal populations in different areas of China published in other studies including Zhuang nationality, the p53 Pro72Arg allele frequence distributions were identical too, while with other races in the world, the results showed some significant differences.2. The genotypes distribution of p53 Pro72Arg polymorphism was significantly different between EC patients and healthy subjects (P=0.03). When Compared with p53 Pro72Arg Arg/Arg genotype, carrying Pro/Arg and (Pro/Pro+Pro/Arg) genotype increased the risk of EC, the age, sex adjusted OR=1.37(95%CI 1.04-1.80)and 1.38(95%CI 1.06-1.79). Furthermore, the risk associated with the Pro/Pro variant genotype was more pronounced in younger patients (≤50 years) (OR, 1.89; 95% CI, 1.03-3.45).Conclusions1. The two high incidence areas of esophageal cancer and cardiac cancer—Chaoshan Littoral in south China and the Taihang Mountains in north China shared same p53 Pro72Arg genetic background. Compared with other reports, it’s identical in Han nationality from different parts of China and Zhuang nationality, too.2. Pro allele might be correlated with EC carcinogenesis in our objective population. The Pro/Pro genotype was significantly associated with the increased risk of EC in younger population.3. p53 Pro72Arg polymorphism Pro/Pro homozygote could be a biomarker associated with EC susceptibility.更多还原