Up-regulation of hypoxia-inducible factors HIF-1α and HIF-2α under normoxic conditions in renal carcinoma cells by von Hippel-Lindau tumor suppressor gene loss of function
Up-regulation of hypoxia-inducible factors HIF-1α and HIF-2α under normoxic conditions in renal carcinoma cells by von Hippel-Lindau tumor suppressor gene loss of function
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DOI：
10.1038/sj.onc.1203938
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发表时间：
2000-11-16
期刊：
影响因子：
8
通讯作者：
Plate, KH
中科院分区：
文献类型：
--
作者：
Krieg, M;Haas, R;Plate, KH
低氧诱导包括促红细胞生成素和血管内皮生长因子在内的一系列重要生理基因的转录。转录激活是由低氧诱导因子-1(HIF-1)介导的，HIF-1是碱性螺旋-环-螺旋PAS家族的异二聚体成员，由α和β亚基组成，HLF-1α与最近发现的也受低氧刺激的HIF-2α蛋白有48%的同源性。在先前对血管母细胞瘤的研究中，我们发现血管内皮生长因子和HIF-2α水平升高。肿瘤间质细胞中的mRNA。VHL抑癌基因突变与多种肿瘤相关，如肾透明细胞癌(RCC)，在本研究中，我们分析了缺氧诱导因子HIF-1α和HIF-2α在一系列VHL野生型和VHL缺陷型RCC细胞系中的表达。在功能性VHL蛋白存在的情况下，HIF-1αmRNA水平升高，而HIF-2αmRNA表达仅在缺乏功能性VHL基因产物的细胞中增加。然而，在蛋白质水平上，在VHL缺乏的细胞系中，两个HIF-α亚基都是结构性表达的，而重新引入一个功能性的VHL基因可以恢复HIF-1α和HIF-2α蛋白在常氧条件下的不稳定性。此外，肾细胞癌和血管母细胞瘤的免疫组织化学分析显示，肿瘤细胞中HIF-1α和HIF-2α的表达上调。这些数据为VHL蛋白在HIF-1α和HIF-2α蛋白介导的血管生成和红细胞生成调节中的作用提供了证据。
Hypoxia induces transcription of a range of physiologically important genes including erythropoietin and vascular endothelial growth factor. The transcriptional activation is mediated by the hypoxia-inducible factor-1 (HIF-1), a heterodimeric member of the basic helix-loop-helix PAS family, composed of alpha and beta subunits, HLF-1 alpha shares 48 per cent identity with the recently identified HIF-2 alpha protein that is also stimulated by hypoxia, In a previous study of hemangioblastomas, the most frequent manifestation of hereditary von Hippel-Lindau disease (VHL), we found elevated levels of vascular endothelial growth factor and HIF-2 alpha. mRNA in stromal cells of the tumors. Mutations of the VHL tumor suppressor gene are associated with a variety of tumors such as renal clear cell carcinomas (RCC), In this study, we analysed the expression of the hypoxia-inducible factors HIF-1 alpha and HIF-2 alpha in a range of VHL wildtype and VHL deficient RCC cell lines. In the presence of functional VHL protein, HIF-1 alpha mRNA levels are elevated, whereas HIF-2 alpha mRNA expression is increased only in cells lacking a functional VHL gene product. On the protein levels, however, in VHL deficient cell lines, both HIF-alpha subunits are constitutively expressed, whereas re-introduction of a functional VHL gene restores the instability of HIF-1 alpha and HIF-2 alpha proteins under normoxic conditions. Moreover, immunohistochemical analyses of RCCs and hemangioblastomas demonstrate up-regulation of HIF-1 alpha and HIF-2 alpha in the tumor cells. The data presented here provide evidence for a role of the VHL protein in regulation of angiogenesis and erythropoiesis mediated by the HIF-1 alpha and HIF-2 alpha proteins.