Topotecan inhibits vascular endothelial growth factor production and angiogenic activity induced by hypoxia in human neuroblastoma by targeting hypoxia-inducible factor-1α and -2α
Topotecan inhibits vascular endothelial growth factor production and angiogenic activity induced by hypoxia in human neuroblastoma by targeting hypoxia-inducible factor-1α and -2α
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DOI：
10.1158/1535-7163.mct-07-2059
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发表时间：
2008-07-01
影响因子：
5.7
通讯作者：
Bosco, Maria Carla
中科院分区：
文献类型：
--
作者：
Puppo, Maura;Battaglia, Florinda;Bosco, Maria Carla
神经母细胞瘤产生血管生成多肽，血管生成的程度与肿瘤的进展和不良的临床预后相关。因此，抑制血管生成因子是一种重要的治疗选择。肿瘤血管生成的主要驱动力之一是缺氧，这是肿瘤微环境特征的氧分压降低。我们研究了拓扑异构酶I抑制剂拓扑替康对缺氧诱导晚期人神经母细胞瘤细胞血管内皮生长因子(VEGF)表达的影响。拓扑替康可拮抗低氧诱导的血管内皮生长因子，并降低体内低氧培养条件培养液在鸡绒毛膜尿囊膜上的血管生成活性。启动子驱动的报告研究表明，低氧诱导因子(HIF)-1α和-2α在低氧诱导的血管内皮生长因子转录激活中都起作用，因为(A)通过与表达载体共转染两种蛋白的过表达导致了血管内皮生长因子启动子的反式激活，这种反式激活可被HIF结合位点的突变所抑制，以及(B)通过RNA干扰靶向下调HIF-1α/2α可抑制低氧刺激的血管内皮生长因子转录活性和蛋白分泌。拓扑替康对缺氧诱导的血管内皮生长因子的抑制作用是通过抑制HIF-1α和HIF-2α蛋白的积累和反式激活而实现的，这种反式激活特性是特异的，需要持续的RNA转录。在用低氧模拟剂去铁胺处理的细胞中也得到了类似的结果。这些数据首次证明拓扑替康是低氧神经母细胞瘤细胞中HIF-1α和HIF-2α亚基的有效抑制剂，导致血管生成活性和血管内皮生长因子表达降低。这些发现的一个重要临床意义是，针对HIF途径的治疗有可能抑制神经母细胞瘤的血管生成和生长。
Neuroblastoma produce angiogenic peptides, and the extent of angiogenesis correlates with tumor progression and poor clinical outcome. Hence, angiogenic factor inhibition represents an important therapeutic option. One of the major drives to tumor angiogenesis is hypoxia, a decrease in oxygen tension that characterizes the tumor microenvironment. We investigated the effects of the topoisomerase I inhibitor, topotecan, on vascular endothelial growth factor (VEGF) induction by hypoxia in advanced-stage human neuroblastoma cells. Topotecan counteracted hypoxic induction of VEGF and decreased angiogenic activity of conditioned medium from hypoxic cultures in vivo in the chick chorioallantoic membrane. Promoter-driven reporter studies showed the role of both hypoxia-inducible factor (HIF)-1 alpha and -2 alpha in VEGF transcription activation by hypoxia, because (a) overexpression of either protein by cotransfection with expression vectors resulted in VEGF promoter trans-activation, which was abrogated by mutation in the HIF-binding site, and (b) targeted knockdown of HIF-1 alpha/ 2 alpha by RNA interference inhibited hypoxia-stimulated VEGF transcriptional activity and protein secretion. Topotecan-inhibitory effects on VEGF induction by hypoxia were mediated through suppression of both HIF-1 alpha and HIF-2 alpha protein accumulation and transactivation properties, which was specific and required ongoing RNA transcription. A similar pattern of results was obtained in cells treated with the hypoxia-mimetic agent, desferrioxamine. These data provide the first evidence that topotecan is a potent inhibitor of HIF-1 alpha- and HIF-2 alpha subunits in hypoxic neuroblastoma cells, leading to decreased VEGF expression and angiogenic activity. An important clinical implication of these findings is that therapies targeted to the HIF pathway have the potential to inhibit neuroblastoma angiogenesis and growth.