Molecular basis for the induction of an angiogenesis inhibitor, thrombospondin-1, by 5-fluorouracil.
Molecular basis for the induction of an angiogenesis inhibitor, thrombospondin-1, by 5-fluorouracil.
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DOI：
10.1158/0008-5472.can-07-6496
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发表时间：
2008-09
期刊：
影响因子：
11.2
通讯作者：
Hong-ye Zhao;A. Ooyama;Masatatsu Yamamoto;R. Ikeda;M. Haraguchi;Sho Tabata;T. Furukawa;Xiao-Fang Che-Xiao-Fan
中科院分区：
文献类型：
--
作者：
Hong-ye Zhao;A. Ooyama;Masatatsu Yamamoto;R. Ikeda;M. Haraguchi;Sho Tabata;T. Furukawa;Xiao-Fang Che-Xiao-Fan
5-氟尿嘧啶(5-FU)是多种实体瘤化疗中最常用的抗癌药物之一。5-FU剂量依赖性地上调人结肠癌KM12C细胞和人乳腺癌MCF7细胞内源性抗血管生成因子血栓反应素-1(TSP-1)的表达水平。我们研究了5-FU诱导KM12C细胞产生TSP-1的分子基础。启动子分析表明，Egr-1结合区域是5-FU诱导TSP-1启动子活性的关键区域。在5-FU处理的KM12C细胞中，Egr-1与TSP-1启动子的结合增加。免疫荧光染色显示，5-FU可显著增加KM12C细胞核内Egr-1的表达水平。小干扰RNA抑制Egr-1的表达可降低TSP-1的表达水平。此外，5-FU还可诱导p38丝裂原活化蛋白激酶(MAPK)和热休克蛋白27(HSP27)的磷酸化。SB203580阻断p38MAPK通路可显著抑制5-FU诱导的KM12C细胞HSP27的磷酸化，降低5-FU诱导的Egr-1和TSP-1的表达。这些结果表明，p38MAPK通路在5-FU诱导Egr-1的表达中起重要作用，而Egr-1的诱导增强了TSP-1启动子的活性，进而产生TSP-1mRNA和蛋白。
5-Fluorouracil (5-FU) is one of the most commonly used anticancer drugs in chemotherapy against various solid tumors. 5-FU dose-dependently increased the expression levels of intrinsic antiangiogenic factor thrombospondin-1 (TSP-1) in human colon carcinoma KM12C cells and human breast cancer MCF7 cells. We investigated the molecular basis for the induction of TSP-1 by 5-FU in KM12C cells. Promoter assays showed that the region with the Egr-1 binding site is critical for the induction of TSP-1 promoter activity by 5-FU. The binding of Egr-1 to the TSP-1 promoter was increased in KM12C cells treated with 5-FU. Immunofluorescence staining revealed that 5-FU significantly increased the level of Egr-1 in the nuclei of KM12C cells. The suppression of Egr-1 expression by small interfering RNA decreased the expression level of TSP-1. Furthermore, 5-FU induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27). Blockade of the p38 MAPK pathway by SB203580 remarkably inhibited the phosphorylation of HSP27 induced by 5-FU and decreased the induction of Egr-1 and TSP-1 by 5-FU in KM12C cells. These findings suggest that the p38 MAPK pathway plays a crucial role in the induction of Egr-1 by 5-FU and that induced Egr-1 augments TSP-1 promoter activity, with the subsequent production of TSP-1 mRNA and protein.