生物钟周期基因2与胰腺导管腺癌预后的相关性分析

Correlation analysis between period circadian clock 2 gene and the prognosis of pancreatic ductal adenocarcinoma

目的寻找胰腺导管腺癌（PDAC）预后相关基因并探讨其分子调控机制。方法从美国国立生物技术信息中心基因表达数据库中选取102例包含完整临床生存资料的 PDAC 患者的基因表达谱数据。从 Transfac 数据库中收集到106个转录因子调控基因集合。使用 PicTar 和 TargetScanS 算法收集到715个 miRNA 靶向调控基因集合。生物学通路数据来源于京都基因与基因组百科全书（KEGG）。已知癌基因数据来自癌基因普查（CGC）数据库。使用单因素 Cox 比例风险模型分析基因表达谱数据与生存时间的相关性，得到全基因组范围内的与生存相关的候选基因。使用超几何分布算法分析3种数据集的基因富集情况。使用 BH-FDR 算法进行多重矫正检验（要求假阳性率＜0．05）。采用 Kaplan-Meier 法对 PDAC 患者进行生存曲线分析。结果单因素 Cox 比例风险模型分析102例PDAC 患者数据后显示，有273个基因与患者的生存时间显著相关（P ＜0．0001）。将273个生存基因针对106个转录因子调控基因集合进行富集分析，得到12个富集生存基因的转录因子靶基因集合。将273个生存基因针对715个 miRNA 靶向调控基因集合进行富集分析，得到11个富集生存基因的miRNA 靶向调控基因集合。将273个生存基因针对 KEGG 通路数据进行富集分析，得到15个富集生存基因的生物学通路。生物钟周期基因2可能在转录水平受到转录因子 CCAAT 框/增强子蛋白（CEBPA）的调控，同时在转录后水平受到 miRNA-32的调控，进而通过昼夜节律通路影响 PDAC 的预后。102例 PDAC 患者按生物钟周期基因2表达量从高到低排序，前51例归为生物钟周期基因2高表达组，其余归为生物钟周期基因2低表达组，行 Kaplan-Meier 生存分析后显示，生物钟周期基因2与PDAC 的预后显著相关（P ＜0．01）。结论CEBPA/miRNA-32/生物钟周期基因2及其相关的生物钟节律通路可能是干预 PDAC 发展的靶通路，与 PDAC 预后相关。

Objective To explore the prognosis related genes of pancreatic ductal adenocarcinoma （PDAC）and investigate the molecular regulation mechanism.Methods Gene expression data of 102 PDAC patients with complete clinical survival data were selected from gene expression database of National Center for Biotechnology Information.The 106 transcription regulation gene collection was collected from Transfac database.The 715 microRNA （miRNA）target regulation gene collection was selected according to PicTar and TargetScanS method.Biological pathway data obtained from the Kyoto Encyclopedia of Genes and Genomes （KEGG）.The known cancer genes were collected from the cancer gene census （CGC） database.Univariate Cox proportional hazards model was used to analyze the correlation between gene expression data and survival time,then obtained survival related candidate genes from the whole genome. Then the enriched genes were analyzed by hypergeometric distribution algorithm from three databases. Multiple correction testing was performed by BH-FDR method （FDR 〈 0.05 ）.Kaplan-Meier was performed for survival curve analysis of PDAC.Results The results of data of 102 PDAC patients analyzed by univariate Cox proportional hazards model indicated that 273 genes were significantly related to the survival time of patients （P 〈0.000 1 ）.After 273 survival genes were enrichment analyzed in 106 transcription factor regulation gene collection,12 survival genes enriched transcription factor target gene sets were found.After 273 survival genes were enrichment analyzed in 715 miRNA target regulation gene collection,11 survival genes enriched miRNAs target sets were discovered.After 273 survival genes were enrichment analyzed in pathway data of KEGG,15 survival genes enriched pathways were obtained. Period circadian clock 2 （PER2 ）was regulated by CCAAT/enhancer binding protein （CEBPA）at transcription level and regulated by miRNA-32 after transcription.The prognosis of PDAC was affected by circadian rhythm pathway.The 102 patients with PDAC were ranked according to the expression of PER2 from high to low,the first 51 cases were included in PER2 higher expression group and the left were included in PER2 lower expression group.Kaplan-Meier survival analysis indicated that PER2 was significantly correlated with prognosis of PDAC （P 〈0.01 ）.Conclusion CEBPA/miRNA-32/PER2 and its related circadian clock pathway may be the target pathway in interfering the development of PDAC,and is correlated with the prognosis of PDAC.