Regulation of Rad51 promoter
Regulation of Rad51 promoter
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DOI：
10.4161/cc.29016
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发表时间：
2014-07-01
期刊：
影响因子：
4.3
通讯作者：
Gorbunova, Vera
中科院分区：
文献类型：
--
作者：
Hine, Christopher M.;Li, Hongjie;Gorbunova, Vera
DNA双链断裂修复和同源重组蛋白Rad51在大多数人类癌症中过表达。这与治疗抵抗和患者存活率降低相关。我们先前表明，含有Rad51启动子融合到报告基因的构建体在癌细胞中的活性平均是正常细胞的850倍。目前还不清楚是什么因素和序列调节Rad51启动子并导致其在癌细胞中的高活性。在这里，我们的特点是调节区域和检查致癌刺激的Rad51启动子的遗传要求。我们确定了负责癌细胞中Rad51启动子上调和下调的特定区域。此外，我们表明Rad51的表达是由EGR1转录因子正调控。然后，我们通过在正常人成纤维细胞中表达一组癌蛋白来模拟恶性转化过程。SV40大T抗原、致癌Ras和SV40小T抗原的不同组合的表达导致Rad51启动子活性逐步增加，所有3种癌蛋白一起导致表达增加47倍。累积起来，这些结果表明，Rad51启动子受多种因素的调节，并且其表达随着细胞向恶性进展而逐渐被激活。
The DNA double-strand break repair and homologous recombination protein Rad51 is overexpressed in the majority of human cancers. This correlates with therapy resistance and decreased patient survival. We previously showed that constructs containing Rad51 promoter fused to a reporter gene are, on average, 850-fold more active in cancer cells than in normal cells. It is not well understood what factors and sequences regulate the Rad51 promoter and cause its high activity in cancerous cells. Here we characterized regulatory regions and examined genetic requirements for oncogenic stimulation of the Rad51 promoter. We identified specific regions responsible for up-and downregulation of the Rad51 promoter in cancerous cells. Furthermore, we show that Rad51 expression is positively regulated by EGR1 transcription factor. We then modeled the malignant transformation process by expressing a set of oncoproteins in normal human fibroblasts. Expression of different combinations of SV40 large T antigen, oncogenic Ras and SV40 small T antigen resulted in step-wise increase in Rad51 promoter activity, with all the 3 oncoproteins together leading to a 47-fold increase in expression. Cumulatively, these results suggest that Rad51 promoter is regulated by multiple factors, and that its expression is gradually activated as cells progress toward malignancy.