Lengyel E, Klostergaard J, Boyd D
Department of Tumor Biology, M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Biochim Biophys Acta. 1995 Jul 20;1268(1):65-72. doi: 10.1016/0167-4889(95)00050-3.
The urokinase-type plasminogen activator plays a central role in tissue remodeling by controlling the synthesis of the extracellular matrix-degrading plasmin. Urokinase expression is transcriptionally regulated by a variety of cytokines including TNF-alpha. The present study was undertaken to identify key transcription factor binding sites in the urokinase promoter necessary for the TNF-alpha-dependent induction of urokinase expression. TNF-alpha treatment of a squamous cell carcinoma cell line, UM-SCC-1, which produces no detectable TNF-alpha, led to a dose-dependent increase in urokinase secretion, thus reflecting a more abundant mRNA. Transient transfections of UM-SCC-1 cells with a CAT reporter driven by 5' deletion fragments of the urokinase promoter indicated that a sequence spanning -2109 to -1870, which contained binding sites for AP-1 and PEA3 was required for the stimulation by TNF-alpha. Mutation of an AP-1 binding site at -1967 and a PEA3 motif at -1973 completely abrogated the inductive effect of TNF-alpha on urokinase promoter activity. Mobility shift assays indicated the presence of a jun-containing factor(s) which bound specifically to the AP-1 sequence present in the urokinase promoter. The amount and/or activity of this factor(s) was greatly enhanced by TNF-alpha treatment. UM-SCC-1 cells transiently transfected with a CAT reporter driven by 3 tandem AP-1 binding sites demonstrated increased CAT activity following TNF-alpha treatment. Thus, the induction of urokinase expression by TNF-alpha is likely to involve the altered expression and/or activity of transcription factors which bind to the AP-1 and PEA3 target sequences in the urokinase promoter.
尿激酶型纤溶酶原激活剂通过控制细胞外基质降解性纤溶酶的合成，在组织重塑中发挥核心作用。尿激酶的表达受包括肿瘤坏死因子-α（TNF-α）在内的多种细胞因子的转录调控。本研究旨在确定尿激酶启动子中对于TNF-α依赖性诱导尿激酶表达所必需的关键转录因子结合位点。用TNF-α处理不产生可检测到的TNF-α的鳞状细胞癌细胞系UM-SCC-1，导致尿激酶分泌呈剂量依赖性增加，从而反映出更丰富的mRNA。用由尿激酶启动子的5'缺失片段驱动的CAT报告基因对UM-SCC-1细胞进行瞬时转染表明，TNF-α刺激需要一个跨越-2109至-1870的序列，该序列包含AP-1和PEA3的结合位点。-1967处的AP-1结合位点和-1973处的PEA3基序的突变完全消除了TNF-α对尿激酶启动子活性的诱导作用。凝胶迁移试验表明存在一种含jun的因子，它特异性结合尿激酶启动子中存在的AP-1序列。TNF-α处理极大地增强了该因子的量和/或活性。用由3个串联AP-1结合位点驱动的CAT报告基因瞬时转染UM-SCC-1细胞，在TNF-α处理后显示CAT活性增加。因此，TNF-α诱导尿激酶表达可能涉及与尿激酶启动子中AP-1和PEA3靶序列结合的转录因子的表达改变和/或活性改变。
