鼻咽癌细胞中ezrin基因启动子上游序列转录调控特性的研究

Transcriptional regulatory properties of DNA sequence upstream of the human ezrin gene promoter in nasopharyngeal carcinoma cells

目的:研究鼻咽癌细胞中ezrin基因启动子上游序列的转录调控特性。方法:构建一系列携带ezrin基因-1541/-706序列的报告基因表达载体,ezrin基因-1541/-706序列以正向和反向分别连接至不含启动子的报告基因上游、ezrin启动子上游、SV40启动子上游、ezrin启动子或SV40启动子控制的报告基因下游,将质粒转染CNE2细胞,检测荧光素酶活性。结果:CNE2细胞中,当-1541/-706序列正向位于报告基因上游时表现出启动子活性,其转录激活作用约为ezrin启动子的50%;反向连接时无启动子活性。而且,当-1541/-706序列正向位于ezrin启动子或SV40启动子上游时,显著提高荧光素酶表达;当反向位于启动子下游、正向或反向位于启动子控制的报告基因下游时,转录增强作用消失。结论:CNE2细胞中ezrin基因启动子上游序列具有转录激活和转录增强作用,这种作用具有DNA序列位置和方向依赖性。

AIM： To investigate transcriptional regulatory properties of DNA sequence upstream of the ezrin gene promoter in nasopharyngeal carcinoma CNE2 cells. METHODS： A series of reporter gene expression vectors carrying ezrin -1541/- 706 sequence were constructed. In forward or reverse orientation, the ezrin -1541/- 706 segment was located upstream of the luc gene in pGL3-Basic, upstream of the ezrin promoter or SV40 promoter, or downstream of the luc gene controlled by ezrin promoter or SV40 promoter. These plasmids were transfected into CNE2 cells for luciferase assay. RESULTS： In CNE2 cells, when the ezrin -1541/- 706 was located upstream of luc gene in pGL3- Basic in the forward orientation, it exhibited transcriptional activation about 50% of ezrin promoter; while this transactivation nearly abolished when this segment was reversed. When this segment was located upstream of the ezrin promoter or SV40 promoter in the forward orientation, it dra- matically increased luciferase expression. However, the transcriptional enhancement disappeared when this segment was located upstream of promoters in the reverse orientation, or downstream of reporter genes in the forward or reverse orientation. CONCLUSION： In CNE2 cells, the DNA sequence upstream of the ezrin promoter could exhibit tran- scriptional activation and enhancement, in a position- and orientation-dependent manner.