SMAD9基因在肺腺癌中的表达及临床意义

Expression and clinical significance of SMAD9 in lung adenocarcinoma

目的探讨SMAD9基因在肺腺癌中的表达变化与临床病理指标以及术后生存之间的关联,为肺腺癌的筛查及其预后提供参考依据。方法基于肿瘤基因图谱(the Cancer Genome Atlas,TCGA)数据库收集的数据,分析SMAD9基因在肺腺癌患者肿瘤组织(510例)和癌旁正常组织(59例)中的表达情况以及与临床病理指标和术后生存的关系。收集肺腺癌患者的肿瘤组织及癌旁正常组织、3-甲基胆蒽(3-MCA)诱导的HBE恶性转化细胞、肺腺癌细胞株,采用qRT-PCR以及Western blot方法检测SMAD9基因的mRNA及蛋白表达水平。采用CCK-8法检测SMAD9过表达和干扰对细胞增殖的影响。结果TCGA数据库分析结果显示,在肺腺癌患者中,肿瘤组织的SMAD9基因的mRNA表达显著低于癌旁正常组织(P<0.01)。qRT-PCR以及Western blot结果都显示,SMAD9基因在3-MCA诱导的HBE恶性转化细胞中呈下调趋势,且在恶转细胞中随着恶转代数增加下调越明显;该基因在肺腺癌组织、多株肺腺癌细胞中的表达均呈现显著下调(P<0.05)。SMAD9基因的表达与N分期及肿瘤分期高度相关(P<0.05)。ROC曲线分析结果显示,SMAD9基因mRNA的表达是一个灵敏度较好的肺腺癌分子筛查标志物(AUC=0.904,95%CI=0.869~0.938,P<0.001)。Kaplan-Meier分析结果显示,肺腺癌患者中,SMAD9基因低表达患者生存时间显著低于高表达患者的生存时间(P<0.05)。过表达SMAD9基因抑制肺腺癌细胞增殖(P<0.01),干扰SMAD9表达后HBE细胞增殖能力显著增强(P<0.01)。结论SMAD9基因在肺腺癌发生、发展过程中表达下调,该基因的表达对肺腺癌患者的筛查和术后生存具有较好的参考价值。

Objective To investigate the mRNA expression of SMAD9 in lung adenocarcinoma,and its relationship with clinicopathological parameters,survival and prognosis,so as to provide some valuable references for the screening and postoperative survival.Methods The expression of SMAD9 in tumor tissues(510 cases)and adjacent normal tissues(59 cases)of lung adenocarcinoma patients and its relationship with clinicopathological parameters and postoperative survival were analyzed based on the Cancer Genome Atlas(TCGA)database.The expression of SMAD9 in tumor tissues and adjacent normal tissues of lung adenocarcinoma patients,HBE malignant transformed cells induced by 3-MCA and lung adenocarcinoma cells were detected by quantitative real-time RT-PCR(qRT-PCR)and Western blotting.The effect of SMAD9 overexpression and interference on cell proliferation was detected by CCK-8 assay.Results The mRNA expression analysis of SMAD9 in TCGA database showed that the expression of SMAD9 was significantly lower in lung adenocarcinoma than adjacent normal tissues(P<0.01).The results of qRT-PCR and Western blotting also showed that the expression of SMAD9 was significantly down-regulated in 3-MCA-induced HBE malignant transformed cells and lung adenocarcinoma tissues and cell lines(P<0.05).The down-regulation of SMAD9 expression was closely correlated with N grade and tumor grade(P<0.05).ROC curve analysis indicated that the mRNA expression of SMAD9 was a sensitive indicator of lung adenocarcinoma(AUC=0.903,95%CI=0.868~0.938,P<0.001).Kaplan-Meier analysis displayed that the survival time of patients with low expression of SMAD9 was significantly shorter than those with high expression(P<0.05).Overexpression of SMAD9 inhibited the proliferation of lung adenocarcinoma cells(P<0.01),and the proliferation of HBE cells was significantly enhanced after interfering with SMAD9 expression as compared with the control cells(P<0.01).Conclusion SMAD9 gene expression is down-regulated in the incidence and development of lung adenocarcinoma.The expression of SMAD9 may be of great value for the screening and postoperative survival of lung adenocarcinoma patients.