CDKN2A基因在非小细胞肺癌中表达及生物学功能生物信息分析

目的探讨细胞周期蛋白依赖激酶抑制剂2A(CDKN2A)在人非小细胞肺癌(NSCLC)中表达、生物学功能和患者预后的关系。方法应用生物信息分析技术探讨癌症基因组图谱数据库(TCGA)中CDKN2A在NSCLC患者肿瘤组织和正常肺组织中的表达情况。采用蛋白-蛋白相互作用(PPI)数据库STRING分析CDKN2A编码蛋白作用网络,并进行聚类分析。采用基因本体论(Gene Ontology,GO)和京都基因与基因组百科全书(Kyoto Encyclopedia of Genes and Genomes,KEEG)富集CDKN2A和相关蛋白的生物学功能和信号通路。同时分析CDKN2A高低表达与NSCLC患者的无疾病进展生存和总生存的关系。同时采用免疫组化检测62例NSCLC患者癌组织和癌旁组织中CDKN2A表达情况分析CDKN2A阳性和阴性表达组患者生存期是否存在差异。结果CDKN2A基因在多种实体肿瘤包括乳腺癌、食管癌、肠癌等中表达水平明显上调。在NSCLC患者癌组织中CDKN2A表达水平明显高于正常肺组织(P<0.05)。而CDKN2A表达水平与肿瘤分期无明显相关性(P>0.05)。CDKN2A相关蛋白PPI网络中,相互作用关系指数为24.8,区域聚类指数为0.74,相互作用蛋白呈现明显的聚类表达(P<0.05)。CDKN2A编码蛋白主要定位在细胞核、细胞膜和囊泡;分子功能主要为蛋白结合、核蛋白结合和铁结合。而生物学过程主要集中于代谢、细胞增殖及对刺激的反应。KEGG信号通路主要为细胞周期调控、DNA蛋白结合以及Wnt信号通路。CDKN2A高表达NSCLC患者总生存期明显低于低表达组,且差异有统计学意义(HR=1.3,P=0.02),而CDKN2A高低表达组间NSCLC患者无疾病进展生存无统计学差异(HR=0.94,P=0.59)。62例NSCLC患者癌组织中CDKN2A阳性表达11例(17.7)而对应癌旁组织中阳性表达49例(79.0%),癌组织中CDKN2A阳性标的率显著高于癌旁组织(P<0.05)。而CDKN2A阳性组与阴性组患者生存期差异无统计学意义(HR=0.99,P>0.05)。结论CDKN2A在NSCLC患者癌组织中表达升高,并与患者预后不良有关,有望成为NSCLC预后和治疗的靶点。

Bioinformatics analysis of CDKN2A gene expression and biological function in NSCLC

Objective To investigate the expression of cyclin-dependent kinase inhibitor 2A(CDKN2A)in human non-small cell lung cancer(NSCLC),its biological function and prognosis.Methods The expression of CDKN2A in Cancer Genome Atlas Database(TCGA)of NSCLC patients and normal lung tissues was investigated by bioinformatics analysis.The protein-protein interaction(PPI)database STRING was used to analyze the interaction network of CDKN2A-encoded proteins,and cluster analysis was carried out.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEEG)were used to enrich the biological functions and signaling pathways of CDKN2A and related proteins.Meanwhile,the relationship between CDKN2A expression and disease-free progression and overall survival of NSCLC patients was analyzed.Immunohistochemistry was used to detect the expression of CDKN2A in cancer tissues and adjacent tissues of 62 patients with NSCLC.The overall survival of patients with positive and negative expression of CDKN2A was analyzed.Results The expression of CDKN2A gene was significantly up-regulated in various solid tumors including breast,esophageal and intestinal cancers.The expression level of CDKN2A in NSCLC patients was significantly higher than that in normal lung tissues(P<0.05).There was no significant correlation between CDKN2A expression and tumor stage(P>0.05).In the PPI network of CDKN2A-related proteins,the interaction relationship index was 24.8,and the regional clustering index was 0.74.The interaction proteins showed obvious clustering expression(P<0.05).CDKN2A encoding proteins were mainly located in nucleus,cell membrane and vesicles,and their molecular functions were protein binding,nucleoprotein binding and iron binding.Biological processes mainly focused on metabolism,cell proliferation and response to stimuli.KEGG signaling pathways included cell cycle regulation,DNA protein binding and Wnt signaling pathways.The total survival time of NSCLC patients with high expression of CDKN2A was significantly lower than that of the low expression group(HR=1.3,P=0.02),while there was no significant difference in disease-free progression survival of NSCLC patients with high expression of CDKN2A(HR=0.94,P=0.59).CDKN2A was positive in 11 cases(17.7)of 62 NSCLC patients and 49 cases(79.0%)of corresponding adjacent tissues.The positive rate of CDKN2A in cancer tissues was significantly higher than that in adjacent normal tissues(P<0.05).There was no significant difference in overall survival between the CDKN2A positive and CDKN2A negative groups(HR=0.99,P>0.05).Conclusion The expression of CDKN2A in cancer tissue of NSCLC patients is elevated,which is related to poor prognosis of NSCLC patients.CDKN2A is expected to be a target for prognosis and treatment of NSCLC.