Role of hypoxia-inducible factor (HIF)-1α-versus HIF-2α in the regulation of HIF target genes in response to hypoxia, insulin-like growth factor-1, or loss of von Hippel-Lindau function:: Implications for targeting the HIF pathway
Role of hypoxia-inducible factor (HIF)-1α-versus HIF-2α in the regulation of HIF target genes in response to hypoxia, insulin-like growth factor-1, or loss of von Hippel-Lindau function:: Implications for targeting the HIF pathway
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DOI：
10.1158/0008-5472.can-05-2519
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发表时间：
2006-06-15
期刊：
影响因子：
11.2
通讯作者：
Ashcroft, Margaret
中科院分区：
文献类型：
--
作者：
Carroll, Veronica A.;Ashcroft, Margaret
缺氧诱导因子（HIF）、HIF-1 α和HIF-2 α的过表达导致参与增殖、血管生成和葡萄糖代谢的基因的上调，并且与几种癌症中的肿瘤进展相关。然而，HIF-1 α与HIF-2 α在不同条件下对血管内皮生长因子（VEGF）表达和其他HIF调节的靶基因的贡献尚不清楚。为了解决这个问题，我们使用小干扰RNA（siRNA）技术来敲低HIF-1 α和/或HIF-2 α的表达，以响应缺氧，胰岛素样生长因子（IGF）-I，或肾癌细胞表达组成性高基础水平的HIF-1 α和/或HIF-2 α由于冯希佩尔-林道（VHL）功能的损失。我们发现，HIF-1 α主要调节VEGF的转录激活响应缺氧和IGF-I相比，HIF-2 α在MCF-7细胞。我们还观察到缺氧时HIF-1 α和HIF-2a表达之间的相互关系：HIF-2 α siRNA增强了MCF-7细胞中HIF-1 α介导的VEGF表达，这可以被HIF-1 α siRNA共转染完全阻断。相反，在VHL功能丧失而组成性表达HIF-1 α和HIF-2 α的肾癌细胞中，我们发现高基础VEGF、葡萄糖转运蛋白-1、尿激酶型纤溶酶原激活物受体和纤溶酶原激活物抑制剂-1表达主要依赖于HIF-2 α。最后，我们发现一种新鉴定的HIF-1小分子抑制剂NSC-134754也能够显著降低肾癌细胞中HIF-2 α蛋白表达和HIF-2 α调节的VEGF水平。我们的数据对我们如何靶向HIF通路治疗具有重要意义。
Overexpression of hypoxia-inducible factors (HIF), HIF-1 alpha and HIF-2 alpha, leads to the up-regulation of genes involved in proliferation, angiogenesis, and glucose metabolism and is associated with tumor progression in several cancers. However, the contribution of HIF-1 alpha versus HIF-2 alpha to vascular endothelial growth factor (VEGF) expression and other HIF-regulated target genes under different conditions is unclear. To address this, we used small interfering RNA (siRNA) techniques to knockdown HIF-1 alpha and/or HIF-2 alpha expression in response to hypoxia, insulin-like growth factor (IGF)-I, or renal carcinoma cells expressing constitutively high basal levels of HIF-1 alpha and/or HIF-2 alpha due to loss of von Hippel-Lindau (VHL) function. We found that HIF-1 alpha primarily regulates transcriptional activation of VEGF in response to hypoxia and IGF-I compared with HIF-2 alpha in MCF-7 cells. We also observed a reciprocal relationship between HIF-1 alpha and HIF-2a expression in hypoxia in these cells: HIF-2 alpha siRNA enhanced HIF-1 alpha-mediated VEGF expression in MCF-7 cells in response to hypoxia, which could be completely blocked by cotransfection with HIF-1 alpha siRNA. In contrast, in renal carcinoma cells that constitutively express HIF-1 alpha and HIF-2 alpha due to loss of VHL function, we found that high basal VEGF, glucose transporter-1, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor-1 expression was predominantly dependent on HIF-2 alpha. Finally, we showed that a newly identified small-molecule inhibitor of HIF-1, NSC-134754, is also able to significantly decrease HIF-2 alpha protein expression and HIF-2 alpha-regulated VEGF levels in renal carcinoma cells. Our data have important implications for how we target the HIF pathway therapeutically.