Objective To investigate the expression and prognostic significance of mediator complex subunit 8 (MED8) in gastric cancer and its impact on the cell cycle.Methods The expression of MED8 in gastric cancer and adjacent tissues and its correlation with patients' prognosis were analyzed using public databases.A validation cohort of 104 patients who underwent radical resection for gastric cancer in the First Affiliated Hospital of Bengbu Medical College from June 2012 to July 2017 was included.The receiver operating characteristic curve was established to evaluate the predictive value of MED8 for postoperative 5-year survival.Bioinformatics tools were used to predict the biological roles of MED8 in gastric cancer.The effect of the MED8 level on the G1/S phase transition of gastric cancer cells (MGC-803) was analyzed via lentivirus transduction and flow cytometry.Western blotting was carried out to assess the impact of MED8 expression on the protein levels of cyclin-dependent kinase 4(Cdk4) and G1/S-specific cyclin-D1(CyclinD1) in MGC-803 cells.Results The high expression of MED8 in the gastric cancer tissue was associated with poor prognosis (P<0.001) and had prognostic significance (area under curve=0.733,P<0.001).Gene enrichment analysis suggested that MED8 may participate in the cell cycle process.Flow cytometry results revealed that the upregulation of MED8 expression promoted the transition of MGC-803 cells from the G1 phase to the S phase (P<0.001),while the downregulation of MED8 had the opposite effect (P<0.001).Western blotting showed increases in the protein levels of Cdk4 and CyclinD1 in MGC-803 cells with upregulated MED8 expression (all P<0.001),and decreases in the cells with downregulated MED8 expression (all P<0.001).Conclusion MED8 is highly expressed in gastric cancer and may affect its progression and prognosis by regulating the G1/S phase transition of gastric cancer cells.
目的 探讨中介体复合物亚基8(MED8)在胃癌中的表达及其与预后的关系和对细胞周期的影响。方法 采用公共数据库分析MED8在胃癌及癌旁组织的表达及其与患者预后的关系,并纳入2012年6月至2017年7月于蚌埠医学院第一附属医院行胃癌根治术的104例患者进行验证。采用受试者工作特征曲线评估MED8对患者术后5年生存率的预测价值;采用生物信息学方法预测MED8在胃癌中的生物学功能;采用慢病毒转染调控胃癌细胞系(MGC-803)中MED8的水平,流式细胞学分析MED8表达水平对MGC-803细胞G1/S期转换的影响。免疫印迹实验检测MED8表达水平对MGC-803细胞中细胞周期蛋白依赖性激酶4(Cdk4)和G1/S-特异性周期蛋白-D1(CyclinD1)蛋白表达的影响。结果 MED8在胃癌组织中高表达与患者不良预后相关(P<0.001),且具有良好的预后预测价值(曲线下面积=0.733,P<0.001);基因富集分析提示MED8可能参与细胞周期进程。流式细胞实验表明上调MED8表达可促进MGC-803细胞从G1期进入S期(P<0.001),下调MED8则相反(P<0.001)。免疫印迹检测显示上调MED8的MGC-803细胞中Cdk4和CyclinD1蛋白水平均显著升高(P均<0.001);下调MED8则相反(P均<0.001)。结论 MED8在胃癌中高表达且可能通过调控胃癌细胞周期G1/S期转换影响疾病进展及预后。.
Keywords: bioinformatics; cell cycle; gastric cancer; mediator complex subunit 8; prognosis.