The proangiogenic phenotype of human tumor-derived endothelial cells depends on thrombospondin-1 downregulation via phosphatidylinositol 3-kinase/Akt pathway
The proangiogenic phenotype of human tumor-derived endothelial cells depends on thrombospondin-1 downregulation via phosphatidylinositol 3-kinase/Akt pathway
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DOI：
10.1007/s00109-006-0075-z
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发表时间：
2006-10-01
影响因子：
4.7
通讯作者：
Carnussi, Giovanni
中科院分区：
文献类型：
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作者：
Bussolati, Benedetta;Assenzio, Barbara;Carnussi, Giovanni
肿瘤来源的内皮细胞（TEC）显示相对于正常内皮细胞的存活率和血管生成特性增加。本研究的目的是探讨TEC促血管生成表型的可能机制。我们发现，血小板反应蛋白-1（TSP-1），一种有效的血管生成的生理抑制剂，显着减少TEC相对于正常内皮细胞。肾透明细胞癌瘤内血管的免疫荧光证实了这种减少。由于TEC显示出磷脂酰肌醇3-激酶（PI 3 K）/ Akt通路的基础上调，我们通过使用LY 294002和渥曼青霉素（PI 3 K抑制剂）和雷帕霉素（哺乳动物雷帕霉素靶蛋白（mTOR）抑制剂）来评估该通路对TSP-1的可能调节。此外，我们开发了Akt的负显性TEC。用LY 294002和渥曼青霉素以及用雷帕霉素处理增强TEC的TSP-1产生，表明通过PI 3 K/Akt/mTOR途径负调节TSP-1表达。此外，在负显性Akt TEC中Akt激活的下调增强TSP-1的表达和释放。外源性TSP-1的管理TEC降低其促血管生成的性质在体外和体内。同时，在阴性显性Akt TEC中用抗TSP-1抗体阻断TSP-1使其促血管生成表型恢复至与野生型TEC相似的水平。总之，这些结果表明，PI 3 K/Akt/mTOR通路的上调是抑制TSP-1合成的原因，TSP-1合成在确定TEC的促血管生成表型中是至关重要的。旨在抑制PI 3 K/Akt/mTOR通路的策略可能通过促进TSP-1的产生来恢复TEC中正常的静止内皮表型。
Tumor-derived endothelial cells (TEC) display increased survival and angiogenic properties in respect to normal endothelial cells. The aim of this study was to investigate the mechanism potentially involved in TEC proangiogenic phenotype. We found that thrombospondin-1 (TSP-1), a potent physiological inhibitor of angiogenesis, was significantly reduced in TEC in respect to normal endothelial cells. This reduction was confirmed by immunofluorescence in the intratumor vessels of clear cell renal carcinomas. As TEC were shown to display a basal upregulation of the phosphatidylinositol 3-kinase (PI3K)/ Akt pathway, we evaluated the possible regulation of TSP-1 by this pathway by using LY294002 and wortmannin, the PI3K inhibitors, and rapamycin, the mammalian target of rapamycin (mTOR) inhibitor. In addition, we developed negative dominant TEC for Akt. TSP-1 production by TEC was enhanced by the treatment with LY294002 and wortmannin and with rapamycin, suggesting a negative regulation of TSP-1 expression by the PI3K/Akt/mTOR pathway. In addition, downregulation of Akt activation in negative dominant Akt TEC enhanced TSP-1 expression and release. Administration of exogenous TSP-1 to TEC reduced their proangiogenic properties in vitro and in vivo. In parallel, blockade of TSP-1 with an anti-TSP-1 antibody in negative dominant Akt TEC restored their proangiogenic phenotype to levels similar to wild-type TEC. In conclusion, these results indicate that the upregulation of the PI3K/Akt/mTOR pathway is responsible for the inhibition of TSP-1 synthesis which is critical in determining the proangiogenic phenotype of TEC. Strategies aimed to inhibit the PI3K/Akt/mTOR pathway may restore a normal quiescent endothelial phenotype in TEC by promoting TSP-1 production.