DNA聚合酶θ在子宫内膜癌中的表达及其临床意义

Expression and clinical significance of DNA polymeraseθin endometrial cancer

目的·探究和验证DNA聚合酶θ(DNA polymeraseθ,POLQ)在子宫内膜癌和正常子宫内膜组织中的差异表达,分析其与子宫内膜癌患者临床特征的关系及对预后判断的价值。方法·应用基因表达数据动态分析(Gene Expression Profiling Interactive Analysis,GEPIA)网站检索POLQ基因在人体各部位癌组织和正常组织的表达情况。从癌症基因组图谱(The Cancer Genome Atlas,TCGA)数据库中下载POLQ基因表达谱及临床数据,经Strawberry Perl软件整理后获得基因表达矩阵,使用R软件比较癌和癌旁组织POLQ表达差异及其表达与临床特征的关系,利用基因探针富集分析(Gene Set Enrichment Analysis,GSEA)揭示POLQ在子宫内膜癌中参与的信号通路。收集127例2011年3月—2014年12月在重庆医科大学第一附属医院接受手术且组织病理学诊断为子宫内膜癌的患者的临床信息,分析不同临床特征患者间POLQ表达的差异;取这些患者的肿瘤组织石蜡切片行免疫组织化学染色,判断肿瘤组织中POLQ表达情况,并以22例子宫肌瘤患者的正常子宫内膜组织作为对照。利用Kaplan-Meier法及多因素Cox回归模型分析POLQ表达与子宫内膜癌患者预后的相关性。结果·通过GEPIA网站检索到POLQ除了在睾丸癌中相对低表达,在多数癌症中表达均升高。TCGA数据库中POLQ在子宫内膜癌组织的表达水平显著高于癌旁组织(P=0.000);POLQ在60岁及以上和高分级患者中的表达水平更高(均P<0.05),且POLQ高表达患者总生存期较短(P=0.000)。GSEA结果显示,POLQ基因主要富集在碱基切除修复通路、同源重组通路、P53通路等。POLQ在正常子宫内膜石蜡切片免疫组织化学染色评分≥1分与≥5分的比例均显著低于子宫内膜癌组织(均P<0.05);≥5分的比例在不同肿瘤分期、淋巴结转移情况的患者间差异有统计学意义(均P=0.038);且POLQ高表达患者无病生存期和总生存期均显著短于POLQ低表达组(均P<0.05)。多因素Cox分析提示POLQ评分可作为子宫内膜癌的独立预后因素。结论·相较于正常子宫内膜,POLQ在子宫内膜癌组织中表达显著升高,尤其在晚期、有淋巴结转移的患者中表达水平更高,且POLQ高表达是子宫内膜癌患者预后差的独立预测因素。

Objective·To explore and verify the differential expression of DNA polymeraseθ(POLQ)in endometrial cancer(EC)and normal endometrial tissues,and analyze its relationship with clinical characteristics of EC patients and its value in prognostic judgement.Methods·Gene Expression Profiling Interactive Analysis(GEPIA)website was used to retrieve the expression of POLQ in cancer tissues and normal tissues in various parts of the human body.The POLQ gene expression profile and the clinical data were downloaded from The Cancer Genome Atlas(TCGA)database.The gene expression matrix was obtained by Strawberry Perl software.The differences in the POLQ expression between EC and paracancerous tissues and the relationship between the POLQ expression and the clinical characteristics were analyzed by R software.Gene Set Enrichment Analysis(GSEA)was used to reveal the signaling pathways in which POLQ participated in EC.The clinical information of 127 patients diagnosed as having EC by histopathology,who underwent surgery in the First Affiliated Hospital of Chongqing Medical University from March 2011 to December 2014,were collected to analyze the differences in the POLQ expression among patients with different clinical characteristics.Immunohistochemical staining was performed on paraffin sections of tumor tissues from these patients to determine the expression of POLQ in the tumor tissues,and normal endometrium tissues from 22 patients with uterine fibroids were used as controls.Kaplan⁃Meier method and multivariate Cox regression model were used to analyze the correlation between POLQ expression and prognosis.Results·It was found that POLQ expression was relatively lower in testicular germ cell tumor,but increased in most cancers through GEPIA website.The expression of POLQ in EC tissues was significantly higher than that in paracancerous tissues in the TCGA database(P=0.000),and POLQ was more expressed in the patients with the age of 60 years and above and in the highly graded patients(both P<0.05).Overall survival of the patients with high expression of POLQ was shorter(P=0.000).The results of GSEA showed that POLQ gene was mainly enriched in the base resection repair pathway,homologous recombination pathway,P53 pathway,etc.The proportions of POLQ scores≥1 and≥5 in the normal endometrial paraffin sections were significantly lower than those in the EC tissues(both P<0.05).The proportion of POLQ score≥5 showed statistically significant difference among the patients with different tumor stages or different conditions of lymph node metastasis(both P=0.038).The disease-free survival and overall survival of the patients with high POLQ expression were significantly shorter than those of the patients with low POLQ expression(both P<0.05).Multivariate Cox analysis showed that POLQ score could be used as an independent prognostic indicator.Conclusion·Compared with normal endometrium,the expression of POLQ significantly increase in EC tissues,especially in patients with advanced stage and lymph node metastasis,and high expression of POLQ is an independent predictor of poor prognosis in EC patients.