【作者】 刘继斌；

【导师】 陈克平；

【作者基本信息】 江苏大学 ， 食品科学， 2012， 博士

【摘要】 肿瘤中异常甲基化是导致基因功能丧失的一个重要机制。叶酸可通过体内代谢反应参与DNA的甲基化而调节染色体DNA的表达。目前消化系统肿瘤多基因甲基化研究主要集中在组织,而血浆中多基因甲基化对肿瘤预后的研究较少。论文应用甲基化特异性PCR方法检测了CpG岛甲基化表型(CIMP),检测了血液中叶酸水平并进行床头流行病学调查分析,建立了适合中国人群的多指标CIMP谱和相关的验证。同时研究了食管癌中相关基因甲基化在Wnt信号通路中的作用。论文的主要结果如下：(1)在肝癌组织、血浆中获得七个基因甲基化表达率都超过15%。提示检测多基因的甲基化状态对肝癌的早期诊断有帮助。在血浆中肿瘤相关的一些基因启动子甲基化与肝癌组织中的表达有很好的相符性。(2)肿瘤组织和血浆中CIMP阳性表达与临床病理特征有一定的联系；CIMP阳性表达暗示了肝癌可能存在或即将发生转移、复发。肝癌患者血浆中CIMP阳性表达可作为肝癌预后不良的检测标志。(3)叶酸摄入与CIMP阳性表达有一定关系,在肝癌病人中适当的增加叶酸摄入也许可以延缓肝癌的发展。(4)血浆中SFRP-1,DKK-3和RUNX-3基因启动子甲基化状态可以单独和共同预测食管癌复发。更多还原

【Abstract】 Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. In general, prognosis remains poor, thus identification of useful molecular prognostic markers is necessary. Aberrant promoter hypermethylation is an important mechanism leading to loss of gene function in tumors including HCC. Folate and methionine are dietary methyl group donors that may be hypothesized to influence DNA methylation. Low folate status or intake was suggested to decrease genomic methylation. Circulating folate concentration was associated with increased gene promoter hypermethylation. The hypermethylated subtype in tumors, called the CpG island methylator phenotype (CIMP) in which multiple genes are concurrently methylated, is a novel marker of tumor progression. Methylation of CpG islands in the promoters of many tumor suppressor genes effectively silences those genes. These epigenetic alterations may be important early events in carcinogenesis and may also be potential biomarkers for early detection. CIMP is an important mechanism in HCC development and may serve as a molecular marker of late-stage HCC with poor prognosis. CIMP status was analyzed using a methylation marker panel in tumor tissues and plasma with methylation-specific polymerase chain reaction and blood folate levels was assayed by using enzyme linked immunosorbent assay(ELISA). Epidemiological study was done in the ward. At the same time, the role of gene methylation related esophageal cancer in the Wnt signaling pathway was studied.The main results of the paper is as follows:(1)The frequencies of high-level methylation in HCC tissue and plasma were at least 15%. The methylation status of multiple genes in plasma may serve as a molecular marker of HCC with the early diagnosis.There is good concordance of DNA methylation in plasma and tumor in HCC.(2) CIMP associated with tumor not only in tumor tissue but also in plasma were significantly different in HCC with Gender,HBsAg,AFP and TNM stage and in nonneoplastic tissues and plasma of healthy controls. The metastatic rate and recurrence rate in CIMP+group were significantly higher than CIMP-group in plasma(p<0.05). In this study,Plasma DNA could be used as a reliable resource and replace tumor tissue for CIMP research. CIMP in plasma could serve as a molecular marker of late stage and poorly prognostic HCC.(3) Blood folate levels is associated with positive expression of CpG island methylation phenotype (CIMP) and CIMP+status and low blood folate levels were frequently be associated with tumor metastasis and recurrence.Increased folate levels in HCC may be prevent the further development of HCC.(4) SFRP-1, DKK-3 and RUNX-3 gene promoter methylation status in plasma can be individually and jointly predict esophageal cancer recurrence. The status of promoter hypermethylation of Wnt antagonists/inhibitors in plasma may serve as a non-invasive prognostic biomarker for ESCC.更多还原