Inhibition of Activator Protein-1 by Sulforaphane Involves Interaction with Cysteine in the cFos DNA-Binding Domain: Implications for Chemoprevention of UVB-Induced Skin Cancer
Inhibition of Activator Protein-1 by Sulforaphane Involves Interaction with Cysteine in the cFos DNA-Binding Domain: Implications for Chemoprevention of UVB-Induced Skin Cancer
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DOI：
10.1158/0008-5472.can-09-0770
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发表时间：
2009-09-01
期刊：
影响因子：
11.2
通讯作者：
Bowden, G. Timothy
中科院分区：
文献类型：
--
作者：
Dickinson, Sally E.;Melton, Tania F.;Bowden, G. Timothy
萝卜硫素是一种异硫氰酸酯，来自十字花科蔬菜，与降低某些癌症的风险有关。虽然萝卜硫素在诱导转录因子Nrf 2中的作用已被广泛研究，但也有证据表明，抑制转录因子激活蛋白-1（AP-1）可能有助于该化合物的化学预防特性。在这项研究中，我们第一次表明，萝卜硫素是有效的，在减少的多重性和肿瘤负荷的UVB诱导的鳞状细胞癌的小鼠模型中使用的化合物和致癌物的共同治疗。我们还表明，萝卜硫素预处理能够降低UVB照射后转基因小鼠皮肤中AP-1荧光素酶的活性。染色质免疫沉淀分析证实，AP-1二聚体的主要成分cFos被萝卜硫素抑制与AP-1 DNA结合位点的结合。核蛋白的电泳迁移率变动分析还表明，萝卜硫素和二酰胺，都已知与半胱氨酸氨基酸反应，是有效的抑制AP-1结合到其响应元件。使用截短的重组cFos和cJun，我们表明，这些蛋白质的DNA结合结构域中的关键半胱氨酸（cFos中的CYS 154和cJun中的CYS 272）的突变导致在电泳迁移率变动分析中对萝卜硫素和二酰胺的敏感性丧失。总之，这些数据表明，AP-1活性的抑制可能是一个重要的分子机制，在鳞状细胞癌的化学预防萝卜硫素。[Cancer Res 2009;69（17）：7103-10]
Sulforaphane is an isothiocyanate derived from cruciferous vegetables that has been linked to decreased risk of certain cancers. Although the role of sulforaphane in the induction of the transcription factor Nrf2 has been studied extensively, there is also evidence that inhibition of the transcription factor activator protein-1 (AP-1) may contribute to the chemopreventive properties of this compound. In this study, we show for the first time that sulforaphane is effective at reducing the multiplicity and tumor burden of UVB-induced squamous cell carcinoma in a mouse model using cotreatment with the compound and the carcinogen. We also show that sulforaphane pretreatment is able to reduce the activity of AP-1 luciferase in the skin of transgenic mice after UVB. Chromatin immunoprecipitation analysis verified that a main constituent of the AP-1 dimer, cFos, is inhibited from binding to the AP-1 DNA binding site by sulforaphane. Electrophoretic mobility shift assay analysis of nuclear proteins also shows that sulforaphane and diamide, both known to react with cysteine amino acids, are effective at inhibiting AP-1 from binding to its response element. Using truncated recombinant cFos and cJun, we show that mutation of critical cysteines in the DNA-binding domain of these proteins (CYS154 in cFos and CYS272 in cJun) results in loss of sensitivity to both sulforaphane and diamide in electrophoretic mobility shift assay analysis. Together, these data indicate that inhibition of AP-1 activity may be an important molecular mechanism in chemoprevention of squamous cell carcinoma by sulforaphane. [Cancer Res 2009;69(17):7103-10]