Zhang Yu, Bao Yong Li, Wu Yin, Yu Chun Lei, Sun Ying, Li Yu Xin
National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun 130024, China.
Cancer Genet Cytogenet. 2010 Jan 15;196(2):124-32. doi: 10.1016/j.cancergencyto.2009.09.004.
The human SLC5A8 gene is a tumor suppressor. Its silencing may contribute to the carcinogenesis and progression of various tumors, which makes this gene an attractive molecular marker and a potential target for diagnosis and therapy. Little is known about transcriptional mechanisms controlling SLC5A8 gene expression. To better understand the molecular mechanisms regulating SLC5A8 expression, we characterized the 5'-regulatory region and a part of exon 1. Luciferase reporter assays of deletion mutants of SLC5A8 promoter demonstrated that a 295-bp region is essential for the basal promoter activity of the SLC5A8 gene. Further analysis indicated that the CCAAT boxes and GC boxes were involved in positive regulation of SLC5A8 promoter. Overexpression of two transcription factors, CCAAT/enhancer binding protein beta (C/EBPbeta) and specific transcription factor 1 (Sp1), upregulated the activities of the human SLC5A8 promoter and protein expression, suggesting that both C/EBPbeta and Sp1 transcription factors might have functions in SLC5A8 transcription. Taken together, our results elucidate the mechanism underlying the regulation of SLC5A8 gene transcription and also define a novel regulatory sequence that may be used to increase expression of the SLC5A8 gene in cancer gene therapy.
人类SLC5A8基因是一种肿瘤抑制基因。其沉默可能促进各种肿瘤的发生和发展，这使得该基因成为一个有吸引力的分子标志物以及诊断和治疗的潜在靶点。关于控制SLC5A8基因表达的转录机制，目前所知甚少。为了更好地理解调节SLC5A8表达的分子机制，我们对其5'-调控区和外显子1的一部分进行了特征分析。SLC5A8启动子缺失突变体的荧光素酶报告基因检测表明，一个295bp的区域对于SLC5A8基因的基础启动子活性至关重要。进一步分析表明，CCAAT盒和GC盒参与了SLC5A8启动子的正调控。两种转录因子CCAAT/增强子结合蛋白β（C/EBPβ）和特异性转录因子1（Sp1）的过表达上调了人类SLC5A8启动子的活性和蛋白表达，这表明C/EBPβ和Sp1转录因子可能在SLC5A8转录中发挥作用。综上所述，我们的结果阐明了SLC5A8基因转录调控的潜在机制，同时也确定了一个新的调控序列，该序列可用于在癌症基因治疗中增加SLC5A8基因的表达。
