The up-regulation of human caspase-8 by interferon-γ in breast tumor cells requires the induction and action of the transcription factor interferon regulatory factor-1
The up-regulation of human caspase-8 by interferon-γ in breast tumor cells requires the induction and action of the transcription factor interferon regulatory factor-1
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DOI：
10.1074/jbc.m313023200
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发表时间：
2004-05-07
影响因子：
4.8
通讯作者：
López-Rivas, A
中科院分区：
文献类型：
--
作者：
Ruiz-Ruiz, C;de Almodóvar, CR;López-Rivas, A
用干扰素-γ（IFN-γ）处理人乳腺肿瘤细胞可提高caspase-8的表达，并通过增加顶端caspase-8的加工和活化使这些细胞对死亡受体介导的凋亡敏感。我们已经鉴定了人caspase-8基因启动子，并研究了IFN-γ处理的MCF-7乳腺肿瘤细胞中caspase-8基因表达的转录调控。我们的研究结果表明，IFN-γ诱导的caspase-8 mRNA的表达上调，通过蛋白质合成依赖性机制，涉及的作用IFN-γ诱导的转录因子干扰素调节因子-1（IRF-1），而不改变mRNA的稳定性。人caspase-8基因启动子缺乏可识别的TATA和CAAT盒，但含有一个共有的Sp1结合位点。我们已经确定了两个主要的IFN-γ诱导的转录起始位点在这些细胞中的S1核酸酶图谱，引物延伸分析证实。启动子的缺失分析定义了负责IFN-γ诱导型启动子活性的82-bp最小区域。在这个区域，我们已经确定了一个IFN刺激的反应元件，这是重要的基础和IFN-γ增强的转录活性。电泳迁移率变动分析表明，IFN-γ在与诱导半胱天冬酶-8 mRNA相似的时间尺度上诱导含有ISRE基序的寡核苷酸探针与IRF-1之间的复合物。在MCF-7细胞中外源表达的IRF-1上调了含有caspase-8启动子的82 bp区域的荧光素酶报告质粒的活性。这些数据定义了IFN-γ可能通过其控制肿瘤细胞对死亡受体介导的凋亡的敏感性的新途径。
Treatment of human breast tumor cells with interferon-gamma (IFN-gamma) elevates caspase-8 expression and sensitizes these cells to death receptor-mediated apoptosis through the increased processing and activation of apical procaspase-8. We have characterized the human caspase-8 gene promoter and studied the transcriptional regulation of caspase-8 gene expression in MCF-7 breast tumor cells treated with IFN-gamma. Our findings show that IFN-gamma induces the up-regulation of caspase-8 mRNA expression through a protein synthesis-dependent mechanism involving the action of the IFN-gamma-inducible transcription factor interferon regulatory factor-1 (IRF-1) and without altering mRNA stability. The human caspase-8 gene promoter lacks recognizable TATA and CAAT boxes but contains a consensus Sp1 binding site. We have identified two major IFN-gamma-inducible transcriptional start sites in these cells by S1 nuclease mapping, confirmed by primer extension analysis. Deletion analysis of the promoter defined an 82-bp minimal region responsible for IFN-gamma-inducible promoter activity. In this region, we have identified an IFN-stimulated response element that is important for both the basal and IFN-gamma-enhanced transcriptional activities. Electrophoretic mobility shift assay analysis demonstrated that IFN-gamma induces a complex between an oligonucleotide probe containing the ISRE motif and IRF-1 over a similar time scale to the induction of caspase-8 mRNA. Exogenously expressed IRF-1 in MCF-7 cells up-regulated the activity of a luciferase reporter plasmid containing an 82-bp region of the caspase-8 promoter. These data define a new pathway through which IFN-gamma might control the sensitivity of tumor cell to death receptor-mediated apoptosis.