Activation of the p21WAF1/CIP1 promoter independent of p53 by the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) through the Sp1 sites
Activation of the p21WAF1/CIP1 promoter independent of p53 by the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) through the Sp1 sites
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DOI：
10.1038/sj.onc.1203963
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发表时间：
2000-11-23
期刊：
影响因子：
8
通讯作者：
Pardee, AB
中科院分区：
文献类型：
--
作者：
Huang, LL;Sowa, Y;Pardee, AB
辛二酰苯胺异羟肟酸（SAHA）是一种新型的组蛋白去乙酰化酶抑制剂，对体外培养的小鼠红白血病细胞有较强的诱导分化作用。我们最近已经证明，SAHA诱导细胞周期停滞和凋亡的人乳腺癌细胞，伴随着上调的周期蛋白依赖性激酶抑制剂，p21（WAF 1/CIP 1）通过p53-独立的机制。在这项研究中，我们使用p21基因表达作为模型系统，以阐明SAHA介导的基因激活的分子机制。用SAHA处理人乳腺癌细胞系MICF 7细胞诱导p21 mRNA作为立即早期基因激活的结果。此外，SAHA主要通过位于相对于转录起始位点的-82和-69的两个Spl位点激活p21启动子。此外，Sp1和Sp3蛋白是与p21启动子的Sp1位点结合的主要因子。然而，SAHA不改变它们的DNA结合活性，这表明SAHA通过改变Spl和Sp3的DNA结合活性以外的机制介导p21启动子活性。使用GAL 4荧光素酶测定系统的进一步研究表明，GAL 4-Spl和GAL 4-Sp3融合蛋白都支持SAHA介导的来自由5个GAL 4 DNA结合位点驱动的启动子的基因活化，且GAL 4-Sp3融合蛋白在没有SAHA处理时是血管抑制性。总的来说，我们的研究结果表明，SAHA激活p21启动子通过Sp1网站，Sp1和Sp3蛋白都可以介导SAHA诱导的基因激活。
Suberoylanilide hydroxamic acid (SAHA) is a novel histone deacetylase inhibitor with high potency in inducing differentiation of cultured murine erythroleukemia cells. We have recently demonstrated that SAHA induces cell cycle arrest and apoptosis in human breast cancer cells, accompanied by up-regulation of the cyclin-dependent kinase inhibitor, p21(WAF1/CIP1) via a p53-independent mechanism. In this study, we used p21 gene expression as a model system to elucidate the molecular mechanism(s) underlying SAHA-mediated gene activation. Treatment of human breast cancer cell line MICF7 cells with SAHA induced p21 mRNA as a consequence of an immediate-early gene activation. Moreover, SAHA activated the p21 promoter primarily through two Spl sites located at -82 and -69 relative to the transcription start site. Furthermore, Spl and Sp3 proteins were the major factors binding to the Spl site of the p21 promoter. However, SAHA did not alter their DNA binding activities, suggesting that SAHA mediates p21 promoter activity by a mechanism other than altering the DNA binding activities of Spl and Sp3, Further studies using the GAL4 luciferase assay system demonstrated that both GAL4-Sp1 and GAL4-Sp3 fusion proteins supported SAHA-mediated gene activation from a promoter driven by five GAL4 DNA binding sites, and that GAL4-Sp3 fusion protein,vas suppressive in the absence of SAHA treatment. Collectively, our results suggest that SAHA activates the p21 promoter through the Spl sites, and that both Spl and Sp3 proteins can mediate SAHA-induced gene activation.