Gerez J, Tedesco L, Bonfiglio J J, Fuertes M, Barontini M, Silberstein S, Wu Y, Renner U, Páez-Pereda M, Holsboer F, Stalla G K, Arzt E
Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET-Partner Institute of the Max Planck Society, Buenos Aires, Argentina.
Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Oncogene. 2015 Sep 10;34(37):4855-66. doi: 10.1038/onc.2014.407. Epub 2014 Dec 15.
Somatic mutations or loss of von Hippel-Lindau (pVHL) happen in the majority of VHL disease tumors, which present a constitutively active Hypoxia Inducible Factor (HIF), essential for tumor growth. Recently described mechanisms for pVHL modulation shed light on the open question of the HIF/pVHL pathway regulation. The aim of the present study was to determine the molecular mechanism by which RSUME stabilizes HIFs, by studying RSUME effect on pVHL function and to determine the role of RSUME on pVHL-related tumor progression. We determined that RSUME sumoylates and physically interacts with pVHL and negatively regulates the assembly of the complex between pVHL, Elongins and Cullins (ECV), inhibiting HIF-1 and 2α ubiquitination and degradation. We found that RSUME is expressed in human VHL tumors (renal clear-cell carcinoma (RCC), pheochromocytoma and hemangioblastoma) and by overexpressing or silencing RSUME in a pVHL-HIF-oxygen-dependent degradation stability reporter assay, we determined that RSUME is necessary for the loss of function of type 2 pVHL mutants. The functional RSUME/pVHL interaction in VHL-related tumor progression was further confirmed using a xenograft assay in nude mice. RCC clones, in which RSUME was knocked down and express either pVHL wt or type 2 mutation, have an impaired tumor growth, as well as HIF-2α, vascular endothelial growth factor A and tumor vascularization diminution. This work shows a novel mechanism for VHL tumor progression and presents a new mechanism and factor for targeting tumor-related pathologies with pVHL/HIF altered function.
大多数VHL病肿瘤中会发生体细胞突变或von Hippel-Lindau（pVHL）缺失，这些肿瘤呈现出组成型活性缺氧诱导因子（HIF），这对肿瘤生长至关重要。最近描述的pVHL调节机制为HIF/pVHL途径调节这一悬而未决的问题提供了线索。本研究的目的是通过研究RSUME对pVHL功能的影响来确定RSUME稳定HIF的分子机制，并确定RSUME在pVHL相关肿瘤进展中的作用。我们确定RSUME对pVHL进行SUMO化修饰并与其发生物理相互作用，负向调节pVHL、延伸蛋白（Elongins）和Cullins（ECV）之间复合物的组装，抑制HIF-1和2α的泛素化和降解。我们发现RSUME在人类VHL肿瘤（肾透明细胞癌（RCC）、嗜铬细胞瘤和血管母细胞瘤）中表达，并且通过在pVHL-HIF氧依赖性降解稳定性报告基因检测中过表达或沉默RSUME，我们确定RSUME对于2型pVHL突变体的功能丧失是必需的。使用裸鼠异种移植试验进一步证实了VHL相关肿瘤进展中功能性RSUME/pVHL相互作用。敲低RSUME并表达pVHL野生型或2型突变的RCC克隆，其肿瘤生长受损，HIF-2α、血管内皮生长因子A和肿瘤血管生成减少。这项工作揭示了VHL肿瘤进展的新机制，并提出了一种针对pVHL/HIF功能改变的肿瘤相关病理学的新机制和因素。
