LMP2A调节EBV相关胃癌细胞中PD-L1的表达

LMP2A regulates PD-L1 expression in EBV associated gastric cancer cells

目的探讨膜潜伏蛋白2A(LMP2A)调节EB病毒(EBV)相关胃癌(EBVaGC)细胞中程序性死亡蛋白-配体1(PD-L1)的表达,并分析LMP2A和PD-L1在胃癌细胞株中的表达及关系。方法选取人胃癌细胞株SNU-719[EBV阳性(EBV+)]、AGS[EBV阴性(EBV-)],采用实时荧光定量聚合酶链式反应(qRT-PCR)方法检测胃癌细胞株SNU-719(EBV+)及AGS(EBV-)中LMP2A和PD-L1基因的表达水平,佛波醇(TPA)诱导SNU-719(EBV+)和AGS(EBV-)中LMP2A的表达后,蛋白质印迹法(WB)检测LMP2A、PD-L1蛋白表达水平的变化。结果PD-L1在EBV阳性细胞株SNU-719(EBV+)中的表达水平明显高于在AGS(EBV-)中的表达水平,差异具有统计学意义(P<0.05)。SNU-719(EBV+)中LMP2A mRNA转录水平明显高于AGS(EBV-)细胞株,差异具有统计学意义(P<0.05);AGS(EBV-)、SNU-719(EBV+)细胞株中PD-L1和LMP2A mRNA转录水平具有一致性。诱导12、24、48 h,LMP2A在SNU-719(EBV+)细胞株中表达呈上升趋势,而AGS(EBV-)细胞株无变化。TPA诱导12 h后,SNU-719(EBV+)细胞PD-L1表达明显升高,而AGS(EBV-)细胞株升高不明显。结论EBV相关胃癌可能通过LMP2A介导的致癌途径上调PD-L1表达,从而引起肿瘤免疫逃逸。这提示阻断LMP2A致癌途径和PD-1/PD-L1检查点抑制通路可为EBV感染的胃癌患者带来潜在临床益处。

Objective To discuss the expression of programmed death protein ligand 1(PD-L1)in EB virus associated gastric cancer(EBVaGC)cells by latent membrane protein 2A(LMP2A),and analyze the expression and correlation between LMP2A and PD-L1.Methods Human gastric cancer cell lines SNU-719[EBV positive(EBV+)]and AGS[EBV negative(EBV-)]were selected.Quantitative real-time PCR(qRTPCR)was used to detect the expression of LMP2A and PD-L1 in gastric cancer cell line SNU-719(EBV+)and AGS(EBV-).Then the cells were induced with phorbol-12-tetradecanoate-13-acetate(TPA),Western blotting(WB)was used to detect the expression levels of LMP2A and PD-L1.Results The expression level of PD-L1 in EBV positive cell line SNU-719(EBV+)was significantly higher than that in AGS(EBV-),and the difference was statistically significant(P<0.05).The transcription level of LMP2A mRNA in SNU-719(EBV+)was significantly higher than that in AGS(EBV-)cell lines,and the difference was statistically significant(P<0.05).The transcription levels of PD-L1 and LMP2A mRNA in AGS(EBV-)and SNU-719(EBV+)cell lines were consistent.At 12,24,and 48 h after induction,the expression of LMP2A in SNU-719(EBV+)cell line showed an upward trend,while the expression of AGS(EBV-)cell line remained unchanged.After 12 h of TPA induction,the expression of PD-L1 in SNU-719(EBV+)cells was significantly increased,while that of AGS(EBV-)cell lines was not significantly increased.Conclusion EBV associated gastric cancer may upregulate the expression of PDL1 through LMP2A-mediated carcinogenic pathway,resulting in tumor immune escape.These findings indicated that simultaneous inhibition of PD-1/PD-L1 and LMP2A may provide potential survival benefits to patients with EBV associated gastric cancer.