PcG家族基因多态性与肝癌易感性的关联研究

发布时间：2018-04-10 10:44

本文选题：肝细胞癌　+ PcG家族　；参考：《吉林大学》2017年硕士论文

【摘要】：肝细胞癌(HCC)是最常见的肝脏恶性肿瘤之一,根据调查发现,HCC的发病率在所有癌症中排名第五位。有研究显示,在2012年全球约有782500例新发HCC病例,死亡病例约745500例,其中中国约占全球总数的50%。导致HCC发生的机制十分复杂,已有的研究认为乙型肝炎病毒(HBV)和丙型肝炎病毒(HCV)的慢性感染和随后肝部的再生循环损伤为HCC的主要病因。同时,遗传和表观遗传因素在HCC的发生、发展中亦发挥重要的作用。在HCC发病机制研究中,学者们发现组蛋白甲基化,尤其是H3K27me3可以通过抑制相关抑癌基因的功能,促进HCC的发生和进展。同时,PcG家族作为H3K27me3的主要催化酶,在HCC的表观遗传学中亦积累了大量的研究工作。总结发现:⑴PcG家族不仅可以通过H3K27依赖途径发挥促癌作用,还可以通过非H3K27依赖途径促进HCC的发生,但机制尚不明确。⑵PcG家族基因多态性和突变与肿瘤发生之间存在显著关联,但目前与HCC易感性之间的关联尚鲜见报道,有待于进一步研究与分析。目的:研究分析PcG家族基因的多态性与HCC的遗传相关性。方法:本次研究纳入HCC患者175例,健康对照者231例,所有研究对象均为中国汉族人。经HCC患者组和正常对照组两组研究对象知情同意后,各抽取外周静脉血5ml,采用血液基因组提取试剂盒(离心柱型)提取406例研究对象的全基因组DNA。本研究中共选择PcG家族3个基因(EZH2,CBX8和EED)的9个多态性位点,分别为:rs2302427,rs3757441,rs41277434,rs4889891,rs62000363,rs9905914,rs1391221,rs7952481和rs974144。应用MALDI-TOF-MS技术来检测本研究所选择的3个基因9个位点的基因型。使用Excel 2007软件录入所有数据并进行整理,采用SPSS 17.0软件对研究对象的数据进行统计分析,用SNPStats在线数据处理程序对基因型进行分析。用均数±标准差(`X±s)来表示统计描述,用中位数(四分位数间距)表示临床指标数据,用百分比表示计数资料;用χ2检验检测SNPs的等位基因频率;对于每个SNP,采用Hardy-Weinberg检验进行检测;用χ2检验来分析照组与病例组之间的SNP基因型分布、等位基因频率;使用非参数检验或单因素方差分析来评价SNP与临床指标参数的关联性.结果:⑴本次研究共纳入HCC患者175例,正常对照者231例。病例组中包含男性147例,女性26例,男女性别比例为5.25:1;对照组中包含男性157例,女性68例,男女性别比例为2.33:1。病例组和对照组的平均年龄分别为56.83±13.37岁和55.21±12.61岁。年龄和性别在两组之间的差异均没有统计学意义(All P0.05)。⑵EZH2基因3个位点和EED基因3个位点的基因型分布均符合Hardy-Weinberg平衡定律。⑶EZH2基因除了rs41277434位点的基因型分布在病例组和对照组之间没有差异之外,其他两个位点(rs2302427和rs3757441)的差异都具有统计学意义(P0.05);EED基因rs4889891,rs62000363和rs9905914位点的基因型分布和等位基因频率在病例组和对照组之间的差异都没有统计学意义(P0.05);CBX8基因rs4889891位点的基因型分布和等位基因频率在病例组和对照组之间的差异无统计学意义,其余两个位点,由于其他基因型和等位基因频率低于1%,不存在统计学意义。⑷在四种遗传模型下,EZH2的三个位点中,除了rs3757441位点的超显性模型(P0.05)和rs41277434位点的隐形模型(P0.05)外,其余均与HCC的发生存在明显关联(P0.05);EED基因3个位点和CBX8基因的3个位点的多态性分布在病例组与对照组之间不具有统计学差异(All P0.05)。⑸单倍型分析结果显示,EZH2基因中单倍型CCA在总样本中占23.69%,其分布在病例组与对照组之间显著不同(OR=2.03;CI,1.29-3.19;P0.05);EED基因的单倍型分析结果显示,在总样本中单倍型的分布在病例组与对照组之间没有显著不同(P0.05);CBX8基因的单倍型分析结果显示,单倍型ATG在总样本中占42.18%,其分布在病例组与对照组之间显著不同(OR=2.44;CI,1.83-3.25;P0.05)。⑹与HCC患者临床相关指标的数量性状分析结果显示,3种基因9个位点中除了EZH2的rs2302427多态性与AST指标具有显著性差异之外(P0.05),其余位点的多态性与HCC患者其他临床指标之间的差异不具有统计学意义(P0.05)。结论:1、EZH2基因三个位点的多态性与HCC的发生之间存在显著关联。⑴携带rs2302427 G等位基因和CCA单倍型的个体具有较高的HCC风险,且rs2302427的G等位基因与临床指标AST显著相关。⑵rs3757441的等位基因频率、基因型分布和遗传模型分析结果在病例组和对照组之间存在明显差异,但rs3757441多态性与HCC患者的临床指标之间没有显著关联。⑶rs41277434等位基因在病例组与对照组之间存在显著差异,且携带C等位基因的个体与携带其他等位基因的个体相比HCC风险降低。2、未发现EED基因三个位点rs7952481、rs1391221和rs974144的多态性与HCC易感性之间存在关联。3、CBX8基因的rs62000363,rs9905914位点的基因型和等位基因频率低于1%,无法进行统计学分析;rs4889891位点的基因型分布和等位基因频率在病例组和对照组之间的差异无统计学意义,与之前的研究结果矛盾,需进行进一步的研究与验证。
[Abstract]:Hepatocellular carcinoma (HCC) is one of the most common malignant tumor of the liver, according to the survey found that the incidence of HCC in all cancer ranked fifth. Studies have shown that in 2012 there are around 782500 new cases of HCC cases, around 745500 deaths, of which Chinese accounted for the total number of 50%. in mechanism the occurrence of HCC is very complex, according to the studies of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection and subsequent regeneration of chronic liver injury is the main cause of the HCC cycle. At the same time, genetic and epigenetic factors in the occurrence of HCC, but also play an important role in the development of research in the pathogenesis of HCC. In the mechanism, the scholars found that histone methylation, especially H3K27me3 can inhibit tumor suppressor gene function, promote the occurrence and development of HCC. At the same time, the PcG family as the main catalytic enzyme H3K27me3, HCC in epigenetics in product Tired of a lot of research work. It was found that the PcG family can not only through the H3K27 dependent pathway to promote cancer, can also occur through non H3K27 dependent pathway to promote HCC, but the mechanism is not clear. The PcG gene polymorphisms and mutations and tumor occurrence between the significant correlation, but correlation between the current and HCC susceptibility was rarely reported, for further research and analysis. Objective: To study correlation of genetic polymorphism analysis of PcG gene family and HCC. Methods: This study included 175 cases of HCC patients and 231 healthy subjects. All the research objects are Chinese by Han people. The group of patients with HCC and normal the control group of two groups of subjects after informed consent, the peripheral venous blood of 5ml were selected, using the blood genomic DNA Extraction Kit (centrifugal column type) extraction of genomic DNA. of 406 subjects in this study were selected family of PcG 3 base Because of (EZH2, CBX8 and EED) of 9 polymorphic loci, respectively: rs2302427, rs3757441, rs41277434, rs4889891, rs62000363, rs9905914, rs1391221, rs7952481 and rs974144. using MALDI-TOF-MS technology to detect the genotype of the selected 3 genes of 9 loci. Excel 2007 software was used to input all the data and finishing on the study of the data were analyzed by SPSS 17 software, the genotypes were analyzed by SNPStats online data processing program. With the mean and standard deviation (`X + s) to represent the statistical description, with the median (four percentile interval) said the clinical data, said the count data were percentage; 2 inspection of SNPs allele frequency; for each SNP, Hardy-Weinberg test was used for detection; 2 test to analyze the SNP genotype between group and case group with chi square distribution, allele frequency; using non parametric The number of correlation test and single factor variance analysis to evaluate the parameters of SNP and clinical index. Results: the present study included 175 HCC patients and 231 normal subjects were included in the case group. 147 cases were male, 26 were female, the gender ratio is 5.25:1; the control group included 157 cases of male and female in 68 cases, the average age of the gender ratio of 2.33:1. and control group were 56.83 + 13.37 and 55.21 + 12.61 years. Age and gender differences between the two groups were not statistically significant (All P0.05). Genotypes of the 3 SNPs of EZH2 gene and EED gene 3 loci were in accordance with the distribution Hardy-Weinberg equilibrium. EZH2 gene rs41277434 locus genotype distribution except that there is no difference between the case group and the control group, the other two loci (rs2302427 and rs3757441) were statistically significant (P0.05); EED gene rs4889891, RS6 Genotype 2000363 and rs9905914 loci and allele frequency distribution differences between the case group and the control group were not statistically significant (P0.05); genotype CBX8 gene rs4889891 locus and allele frequency distribution differences between the case and control groups were not statistically significant, the remaining two loci, because of the other genotype and allele frequencies of less than 1%, there is no statistical significance. In four kinds of genetic models, three loci of EZH2, in addition to overdominance model rs3757441 loci (P0.05) contact model and rs41277434 loci (P0.05), the rest were significantly associated with the occurrence of HCC (P0.05); polymorphism of 3 EED loci and 3 loci of the CBX8 gene has no statistical difference between the case group and the control group (All P0.05). The haplotype analysis showed that haplotype of EZH2 gene in CCA accounted for 23 of the total sample .69%, which is distributed between the case group and the control group were significantly different (OR=2.03; CI, 1.29-3.19; P0.05); EED gene haplotype analysis results show that the distribution of haplotypes in the total sample between the case group and the control group were not significantly different (P0.05); CBX8 gene haplotype analysis results showed that haplotype ATG 42.18% of the total sample, the distribution between case group and control group were significantly different (OR=2.44; CI, 1.83-3.25; P0.05). 6 quantitative traits analysis results in patients with HCC related clinical indexes showed that 3 genes of 9 loci except rs2302427 EZH2 polymorphism and AST index had significant difference (except P0.05), the differences between the remaining polymorphisms and other clinical indicators of HCC patients was not statistically significant (P0.05). Conclusion: 1. There was significant correlation between EZH2 gene polymorphism and three loci of HCC. 1 with rs2302427 G The alleles and CCA haplotype in individuals with higher risk of HCC and rs2302427 were significantly correlated with the G allele of AST rs3757441. The clinical indicators of the allele frequency, genotype distribution and genetic model analysis results between the case group and the control group have obvious difference, but there was no significant association between rs3757441 polymorphism of clinical indicators in patients with HCC. The rs41277434 allele has significant difference between the case group and the control group, and the individuals carrying the C allele compared with other allele HCC reduced the risk of.2, found EED gene three loci rs7952481, there is an association between.3 polymorphism and rs974144 and rs1391221 the susceptibility to HCC, CBX8 gene rs62000363, rs9905914 locus genotype and allele frequencies of less than 1%, can not be analyzed statistically; rs4889891 locus genotype distribution and allele frequency The difference between the case group and the control group was not statistically significant, and it was inconsistent with the previous research results, and further research and verification were needed.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R735.7

【参考文献】