胃癌组织中PCDH8基因甲基化及Dnmt1表达关系的研究

发布时间：2018-03-07 16:18

本文选题：胃肿瘤　切入点：PCDH8　出处：《青岛大学》2017年硕士论文　论文类型：学位论文

【摘要】：胃癌是一种死亡率很高的恶性肿瘤,大部分胃癌患者确诊时已处于晚期阶段,早期诊断十分重要。胃癌产生与演变过程极为复杂,涉及环境、遗传等各个方面,其中DNA甲基化在胃癌发生过程中发挥重要作用。PCDH8(protocadherin-8,原钙粘蛋白-8)是一种新的抑癌基因,是原钙粘蛋白家族的成员。研究发现,PCDH8基因的表达减少或缺失受其启动子甲基化的影响,与多种肿瘤关系密切。研究目的:1.检测PCDH8基因在人类胃癌组织及癌旁正常组织中的甲基化状态,分析PCDH8基因与胃癌TNM分期及是否存在淋巴转移之间的相关性。2.分析PCDH8与Dnmt1(细胞内甲基转移酶1)两者之间的相关性。3.探讨PCDH8与Dnmt1在胃癌发生及发展过程中发挥的生物学作用。研究方法:收集2012年7月-2013年9月在青岛大学医学院附属青岛市市立医院普外科行手术切除的60例胃癌患者的新鲜胃癌组织及其相应的癌旁组织标本,胃癌组织取自癌灶中央非坏死区域,癌旁组织取自距离癌组织5cm以上,且术前未行放疗、化疗、靶向治疗等抗肿瘤治疗。通过甲基化特异性聚合酶链式反应(methylationspecific PCR,MSP)的方法检测PCDH8基因启动子区甲基化情况,并分析在60例胃癌组织和其癌旁正常胃粘膜组织中的差异;采用免疫组化SP法检测胃癌组织以及相应的癌旁组织中PCDH8基因蛋白及Dnmt1蛋白的表达水平,综合分析PCDH8及Dnmt1表达与胃癌的关系,并对胃癌中PCDH8基因甲基化及Dnmt1蛋白表达的关系进行初步探讨。结果:PCDH8甲基化的阳性表达率在癌旁正常胃粘膜组织中仅为3.3%(2/60),而PCDH8甲基化的阳性表达率在胃癌组织中为55.0%(33/60),差异具有统计学意义(χ2=38.76,p0.001);胃癌患者肿瘤组织中PCDH8的甲基化率与是否存在淋巴结转移的差异具有统计学的意义(χ2=17.47,p0.001),而与肿瘤的TNM分期以及病人的年龄、性别等差异均没有统计学意义(p均0.05)。PCDH8蛋白在胃癌组织的表达率(11.7%)远远低于其在癌旁正常胃粘膜组织中的表达率(90.0%)(χ2=73.65,p0.001),而癌旁正常胃粘膜组织中Dnmt1蛋白的阳性表达率(5.0%)明显低于胃癌组织中Dnmt1蛋白的阳性表达率(73.3%)(χ2=58.79,p0.001)。在胃癌组织中检测的PCDH8蛋白与Dnmt1蛋白的表达呈负相关(r=-0.544,p0.001)。结论:PCDH8基因在胃癌组织中呈低表达,DNMT1在癌组织中高表达,表明其可能与胃癌发生关系密切。PCDH8基因甲基化以及Dnmt1表达的增高可能参与了胃癌的发生和发展过程。胃癌组织中DNMT1的蛋白的高表达,可能导致抑癌基因PCDH8基因启动子区发生异常甲基化,使抑癌基因蛋白表达减少,失去了对肿瘤发生的抑制作用。
[Abstract]:Gastric cancer is a kind of malignant tumor with high mortality. Most patients with gastric cancer are in advanced stage by the time of diagnosis. Early diagnosis is very important. The process of gastric cancer production and evolution is very complicated, involving various aspects such as environment, heredity and so on. Among them, DNA methylation plays an important role in gastric carcinogenesis. PCDH8- 8 (procalcitonin -8) is a new tumor suppressor gene and a member of procadherin family. It has been found that the decreased or missing expression of PCDH8 gene is affected by its promoter methylation. Objective: 1. To detect the methylation status of PCDH8 gene in human gastric cancer tissues and adjacent normal tissues. To analyze the correlation between PCDH8 gene and TNM stage and lymphatic metastasis of gastric cancer. 2. To analyze the correlation between PCDH8 and Dnmt1 (intracellular methyltransferase 1). 3. To study the relationship between PCDH8 and Dnmt1 in the development and development of gastric cancer. Methods: from July 2012 to September 2013, fresh gastric cancer tissues and corresponding adjacent tissues were collected from 60 patients with gastric cancer who underwent surgical resection in general surgery, Qingdao Municipal Hospital affiliated to Qingdao University Medical College, from July 2012 to September 2013. The tissues of gastric cancer were taken from the non-necrotic area in the center of the cancer focus, and the adjacent tissues were taken from the tissues more than 5 cm from the cancerous tissue, and they were not treated with radiotherapy and chemotherapy before operation. Methylation specific polymerase chain reaction (methylation specific polymerase chain reaction) was used to detect methylation of promoter region of PCDH8 gene, and the difference was analyzed in 60 cases of gastric cancer and its adjacent normal gastric mucosa. Immunohistochemical SP method was used to detect the expression of PCDH8 gene protein and Dnmt1 protein in gastric cancer tissues and adjacent tissues. The relationship between PCDH8 and Dnmt1 expression and gastric cancer was analyzed. The relationship between the methylation of PCDH8 gene and the expression of Dnmt1 protein in gastric cancer was studied. Results the positive rate of methylation of PCDH8 gene in normal gastric mucosa adjacent to gastric cancer was only 3.3 / 60%, while the positive rate of PCDH8 methylation in gastric cancer tissue was 3.3 / 60%. The difference was statistically significant (蠂 2: 38.76%, p 0.001). The methylation rate of PCDH8 was significantly different from the presence of lymph node metastasis in gastric cancer (蠂 2 + 17.47%, p 0.001), but the TNM stage of the tumor and the age of the patient were statistically significant (蠂 2 / 17. 47%, P 0. 001, P 0. 001, P < 0. 05), and the difference was statistically significant (蠂 2 + 17. 47%, P 0. 001). The expression rate of PCDH8 protein in gastric cancer tissues was significantly lower than that in adjacent normal gastric mucosa tissues. (蠂 2 + 73.65%, p 0.001), and the positive expression rate of Dnmt1 protein in adjacent normal gastric mucosa tissues was 5.0% (P < 0.05). The positive expression rate of Dnmt1 protein in gastric cancer was significantly lower than that in gastric carcinoma (蠂 2 / 58.79 / p 0.001). There was a negative correlation between the expression of PCDH8 protein and Dnmt1 protein in gastric cancer tissue. Conclusion the low expression of DNMT1 gene was found in gastric cancer tissue. It is suggested that the methylation of PCDH8 gene and the increase of Dnmt1 expression may be involved in the carcinogenesis and progression of gastric cancer. It may lead to abnormal methylation in the promoter of tumor suppressor gene PCDH8 gene and decrease the expression of tumor suppressor gene protein.
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R735.2

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