食管癌细胞ezrin基因启动子TPA反应性的研究

TPA Responsiveness of ezrin Gene Promoter in Esophageal Carcinoma Cells

背景与目的:研究食管癌细胞ezrin基因启动子的TPA反应性以及TPA诱导ezrin基因转录的MAPK信号转导途径。材料与方法:应用转录因子数据库分析预测ezrin基因-87/+134序列的潜在转录因子结合位点和TPA反应元件;采用双荧光素酶报告基因分析系统,检测ezrin基因-87/+134序列的启动子活性和TPA反应性,TPA反应元件结合蛋白Sp1和AP-1对ezrin基因的转录激活作用,以及MAPK抑制剂对TPA诱导激活的ezrin基因转录的抑制作用。结果:ezrin基因-87/+134序列存在潜在TPA反应元件,具有启动子活性;5ng/mlTPA显著增强ezrin基因启动子活性(P<0.01);Sp1和AP-1对ezrin基因具有转录激活作用;MEK1/2特异性抑制剂U0126和PD98059降低TPA诱导的ezrin基因转录激活作用。结论:食管癌细胞中,ezrin基因启动子具有TPA反应性;TPA可能通过MEK/ERK1/2磷酸化Sp1/AP-1途径调控ezrin基因转录。

BACKGROUND AND AIM：To identify the TPA responsiveness of ezrin gene promoter and the mitogen-activated protein kinase（MAPK） signal pathway of TPA-induced ezrin transcription in esophageal carcinoma cells.MATERIALS AND METHODS：The potential transcription factors and TPA-responsive elements（TRE） were analyzed and predicted using transcription factor database.Using dual-luciferase reporter assay system,we determined the promoter activity and TPA responsiveness of ezrin gene-87/＋134 sequence,the transactivation of TRE binding proteins Sp1 and AP-1 on ezrin, and the inhibition of MAPK inhibitors on TPA-induced ezrin transaetivation. RESULTS： Ezrin gene -87/＋ 134 sequence had potential TPA-responsive elements and exhibited promoter activity. 5 ng/ml TPA increased ezrin promoter activity significantly（P〈0.01） Spl and AP-1 transactivated ezrin gene. MEK1/2 specific inhibitors U0126 and PD98059 decreased the TPA-induced ezrin transactivation. CONCLUSION： Ezrin gene promoter demonstrated TPA responsiveness in esophageal carcinoma cells. TPA may regulate ezrin transcription via MEK/ERK1/2 phosphorylating Spl and AP-1 pathways.