Reuning U, Guerrini L, Nishiguchi T, Page S, Seibold H, Magdolen V, Graeff H, Schmitt M
Frauenklink der Technischen Universität München, Germany.
Eur J Biochem. 1999 Jan;259(1-2):143-8. doi: 10.1046/j.1432-1327.1999.00014.x.
Elevated levels of the urokinase-type plasminogen activator (uPA) in tumor cells are conductive to tumor cell spread and metastasis. In a previous study we observed that suppression of RelA dramatically reduced endogenous uPA synthesis in the human ovarian cancer cell line OV-MZ-6. Because the uPA promoter contains three potential Rel-like protein binding motifs (RRBE, 5'-NF-kappaB, and 3'-NF-kappaB) we conducted the first thorough systematic uPA promoter analysis to examine the direct impact of Rel proteins on uPA gene transcription. Disruption of RRBE resulted in a approximately 40% decrease in uPA promoter activity, mutation of the 5'-NF-kappaB motif led to an additional 20% decrease. The 3'-NF-kappaB motif was not active. Overexpression of RelA significantly enhanced uPA promoter activity, whereas IkappaB-alpha overexpression reduced uPA promoter activity by 40%. These data were supported by the finding that endogenous uPA was also increased sixfold by overexpression of RelA and decreased by 30% upon overexpression of IkappaB-alpha. Transfection of OV-MZ-6 cells with antisense deoxynucleotides directed to RelA expression reduced uPA promoter activity by at least 40%. Our data clearly suggest that by binding to uPA promoter elements, Rel transcripton factors contribute directly to elevated uPA gene expression in human ovarian cancer cells, thereby promoting the multiple functions of uPA during tumor growth and metastasis.
肿瘤细胞中尿激酶型纤溶酶原激活剂（uPA）水平升高有助于肿瘤细胞的扩散和转移。在先前的一项研究中，我们观察到RelA的抑制显著降低了人卵巢癌细胞系OV-MZ-6中内源性uPA的合成。由于uPA启动子包含三个潜在的Rel样蛋白结合基序（RRBE、5'-NF-κB和3'-NF-κB），我们进行了首次全面系统的uPA启动子分析，以研究Rel蛋白对uPA基因转录的直接影响。RRBE的破坏导致uPA启动子活性降低约40%，5'-NF-κB基序的突变导致额外降低20%。3'-NF-κB基序无活性。RelA的过表达显著增强了uPA启动子活性，而IκB-α的过表达使uPA启动子活性降低了40%。这些数据得到了以下发现的支持：RelA的过表达也使内源性uPA增加了六倍，而IκB-α的过表达使其降低了30%。用针对RelA表达的反义脱氧核苷酸转染OV-MZ-6细胞可使uPA启动子活性降低至少40%。我们的数据清楚地表明，Rel转录因子通过与uPA启动子元件结合，直接促进人卵巢癌细胞中uPA基因表达的升高，从而在肿瘤生长和转移过程中促进uPA的多种功能。
