关键词: TPA反应性, ezrin基因, 食管癌细胞, 启动子活性, 双荧光素酶报告基因分析系统

Abstract: 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 transactivation. 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). Sp1 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 phosphoryla- ting Sp1 and AP-1 pathways.

Key words: TPA responsiveness, ezrin gene, esophageal carcinoma cell, promoter activity, dual-luciferase reporter assay system