Phase II enzyme inducer, sulforaphane, inhibits UVB-induced AP-1 activation in human keratinocytes by a novel mechanism
Phase II enzyme inducer, sulforaphane, inhibits UVB-induced AP-1 activation in human keratinocytes by a novel mechanism
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DOI：
10.1002/mc.20052
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发表时间：
2004-11-01
影响因子：
4.6
通讯作者：
Bowden, GT
中科院分区：
文献类型：
--
作者：
Zhu, M;Zhang, YS;Bowden, GT
紫外线（UV）诱导的激活蛋白1 （AP-1）的激活，至少部分是由氧化应激引起的，促进了皮肤癌的发生。目前尚未确定细胞II期酶和谷胱甘肽（GSH）水平升高是否会抑制AP-1的激活。因此，我们研究了两种众所周知的II期酶诱导剂，萝卜硫素（SF）和叔丁基对苯二酚（tBHQ）对uvb诱导的AP-1激活的影响，并将AP-1荧光素酶报告质粒稳定转染到人HaCaT角质形成细胞（HCL14细胞）中。将HCL14细胞暴露于SF或thbhq可诱导醌还原酶-1 (QR-1)，这是细胞整体II期酶的标志，并可升高细胞GSH水平。1-10 muM SF或11-45 muM thbhq孵育24 h后，QR-1活性分别增加1.4倍和1.7倍，细胞GSH水平分别增加1.5倍和1.6倍。250 J/m(2)的UVB照射HCL14细胞后，AP-1的激活显著增强。虽然上述SF处理剂量依赖性地降低了uvb诱导的HCL14细胞中AP-1的激活，但tBHQ处理没有，这表明提高细胞II期酶和GSH水平可能不会抑制uvb诱导的AP-1激活。事实上，消耗80%的细胞GSH也不会影响uvb诱导的AP-1激活。随后的电泳迁移迁移试验（EMSA）显示，直接添加到EMSA中的SF抑制AP-1 DNA结合活性，而thbhq则无效。综上所述，我们的研究结果表明，升高人角质形成细胞中的II期酶和CSH水平不会导致uvb诱导的AP-1激活的显著抑制。SF对uvb诱导的AP-1激活的抑制作用似乎至少部分是由于直接抑制AP-1的DNA结合活性。SF对AP-1 DNA结合的直接影响是AP-1活化药物抑制剂作用的新机制。(C) 2004 Wiley-Liss, Inc。
Ultraviolet (UV) light-induced activation of activator protein-1 (AP-1), resulting at least in part from oxidative stress, promotes skin carcinogenesis. It has not yet been determined whether elevating cellular phase II enzymes and glutathione (GSH) levels inhibits the AP-1 activation. We have, therefore, examined the effects of two well-known inducers of phase II enzymes, sulforaphane (SF) and tert-butylhydroquinone (tBHQ), on UVB-induced AP-1 activation, with an AP-1-luciferase reporter plasmid that was stably transfected into human HaCaT keratinocytes (HCL14 cells). Exposure of HCL14 cells to SF or tBHQ led to the induction of quinone reductase-1 (QR-1), a marker of global cellular phase II enzymes, as well as elevation of cellular GSH levels. Incubation of the cells with 1-10 muM SF or 11-45 muM tBHQ for 24 h resulted in up to 1.4-fold and 1.7-fold increase of QR-1 activity, respectively, and up to 1.5-fold and 1.6-fold increases in cellular GSH levels, respectively. AP-1 activation was dramatically enhanced by irradiating HCL14 cells with 250 J/m(2) of UVB. While the above SF treatment dose-dependently reduced the UVB-induced AP-1 activation in HCL14 cells, the tBHQ treatment did not, suggesting that elevating cellular phase II enzymes and GSH levels may not lead to inhibition of UVB-induced AP-1 activation. Indeed, depleting cellular GSH by 80% did not affect UVB-induced AP-1 activation either. Subsequent electrophoretic mobility shift assays (EMSA) showed that SF added directly to the EMSAs inhibited AP-1 DNA binding activity, whereas tBHQ was ineffective. Taken together, our results indicated that elevating phase II enzymes and CSH levels in human keratinocytes does not lead to significant inhibition of UVB-induced AP-1 activation. The inhibitory effect of SF on UVB-induced AP-1 activation appears to be at least partly due to the direct inhibition of AP-1 DNA binding activity. This direct effect of SF on AP-1 DNA binding is a novel mechanism for the action of a drug inhibitor of AP-1 activation. (C) 2004 Wiley-Liss, Inc.