DNA甲基化与食管鳞状细胞癌患者化疗敏感性的相关性研究

发布时间：2018-02-04 15:11

本文关键词： 食管鳞癌 DNA甲基化化疗敏感性预后癌症基因组图谱 IRAK3　出处：《北京协和医学院》2017年博士论文　论文类型：学位论文

【摘要】：实验背景:食管癌是全世界范围内发病率第8位、死亡率第6位的恶性肿瘤。我国食管癌约90%为食管鳞癌,尽管已有手术、放疗、化疗等联合治疗可以改善患者生存,但食管癌的五年生存率仍不足15%。其中不同化疗方案均表现出较低的患者有效率,所以寻找预测化疗药物敏感性的标志物已成为改善患者预后的关键。DNA甲基化作为重要的表观遗传学修饰,对肿瘤的发生发展有着相当重要的作用,展现出在肿瘤早期筛查、预后评估、化疗敏感性预测等方面的巨大价值。实验方法:利用全基因组甲基化高密度芯片(Infinium HD human Methylation450K BeadChip)检测对紫杉醇联合顺铂化疗方案敏感性不同的食管鳞癌组织样本12例,利用生物信息技术分析检测数据,筛选敏感组与耐药组之间的差异甲基化位点和基因。联合同一样本表达谱数据行关联分析,筛选由DNA甲基化异常导致基因表达改变的候选基因。利用癌症基因组图谱计划(TCGA)食管鳞癌数据,验证候选基因甲基化水平是否与患者生存预后相关,行Cox多因素回归分析筛选最终可预测患者化疗敏感性和预后的异常甲基化基因。实验结果:本实验共筛选出敏感组与耐药组之间差异甲基化位点共40985个(p0.05),启动子区差异甲基化基因共425个(p0.05,FDR0.05),其中高甲基化基因34个,低甲基化基因391个,多与化学物质刺激应答、信号传导等通路相关。甲基化谱与表达谱关联分析,筛选出DNA甲基化异常导致基因表达改变的候选基因共12个。TCGA食管鳞癌数据验证得到其中6个基因甲基化水平与其表达具有相关性(相关系数-0.3,p0.05),Cox多因素回归分析显示性别(p=0.036,HR=0.209,95%CI[0.048,0.905])、初治后有无新发肿瘤(p=0.027,HR=1.119,95%CI[1.120,6.700])以及基因 IRAK3 甲基化水平(p=0.039,HR=0.036,95%CI[0.036,0.920])是食管鳞癌患者的独立预后因素。实验结论:紫杉醇联合顺铂化疗方案下,敏感组与耐药组的食管鳞癌标本对比发现启动子区域差异甲基化基因共425个,与化学物质刺激应答、信号传导等重要通路相关。其中由DNA甲基化异常导致基因表达改变的基因12个,包含已知的抑癌基因和多个转录调控相关基因。经TCGA食管鳞癌数据验证,基因IRAK3的甲基化水平为食管鳞癌患者的独立预后因素,IRAK3高甲基化食管鳞癌患者死亡风险更低,可作为食管鳞癌患者预后预测的分子标志物,与化疗敏感性的关系尚需进一步验证。
[Abstract]:Background: esophageal cancer is the 8th most common malignant tumor in the world and the sixth most fatal malignant tumor. About 90% esophageal carcinoma in China are esophageal squamous cell carcinoma despite the operation and radiotherapy. Chemotherapy and other combined treatment can improve the survival of patients, but the 5-year survival rate of esophageal cancer is still less than 15%. Therefore, searching for markers to predict chemosensitivity has become the key to improve the prognosis of patients. DNA methylation is an important epigenetic modification, which plays an important role in tumor development. Demonstrated early screening and prognostic evaluation of the tumor. Great value in prediction of chemosensitivity. Experimental methods: using high density microarray for genomic methylation. Infinium HD human Methylation450K BeadChip). 12 cases of esophageal squamous cell carcinoma with different sensitivity to paclitaxel and cisplatin chemotherapy were detected. Bioinformatics was used to analyze the detection data and to screen the differential methylation sites and genes between sensitive and resistant groups. The association analysis was performed with the expression profile data of the same sample. To screen candidate genes for gene expression changes caused by abnormal DNA methylation. TCGA-based esophageal squamous cell carcinoma data were obtained by cancer genome mapping project. To verify whether the methylation level of candidate gene is related to survival and prognosis of patients. Cox multivariate regression analysis was performed to screen abnormal methylation genes that ultimately predict chemosensitivity and prognosis in patients. A total of 40985 differentially methylated sites were screened between sensitive and resistant groups. P0.05). There were 425 differentially methylated genes in promoter region, including 34 hypermethylation genes and 391 hypomethylated genes, which were mostly responsive to chemical stimulation. Correlation between signal transduction and other pathways. Correlation analysis between methylation spectrum and expression spectrum. A total of 12 candidate genes with abnormal DNA methylation resulting in gene expression changes were screened. Data from TCGA esophageal squamous cell carcinoma showed that 6 of them were correlated with their expression (P < 0.05). Correlation coefficient -0.3. The multivariate regression analysis of p0.05 and Cox showed that the sex was 0.036% HRL 0.209% CI. [0.048% 0.905], if there is a new tumor after initial treatment, there are 0.027 HRT and 1.11919 / 95 CI. [) and the IRAK3 methylation level of the gene P0.039, HRN 0.036 95 CI. [Conclusion: paclitaxel combined with cisplatin chemotherapy is an independent prognostic factor in patients with esophageal squamous cell carcinoma. A total of 425 promoter region differentially methylated genes were found in esophageal squamous cell carcinoma specimens from sensitive and drug-resistant groups, which were stimulated by chemical substances. Signal transduction and other important pathways are related, of which 12 genes caused by abnormal DNA methylation caused gene expression changes. TCGA esophageal squamous cell carcinoma data confirmed that the methylation level of gene IRAK3 was an independent prognostic factor in esophageal squamous cell carcinoma patients. The risk of death in patients with hypermethylated esophageal squamous cell carcinoma (IRAK3) is lower, which can be used as a molecular marker for predicting prognosis in patients with esophageal squamous cell carcinoma. The relationship between IRAK3 and chemosensitivity needs to be further verified.
【学位授予单位】：北京协和医学院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R735.1

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