Endothelial Cell mTOR Complex-2 Regulates Sprouting Angiogenesis
Endothelial Cell mTOR Complex-2 Regulates Sprouting Angiogenesis
复制标题
DOI：
10.1371/journal.pone.0135245
复制
发表时间：
2015-08-21
期刊：
影响因子：
3.7
通讯作者：
Murray, Allan G.
中科院分区：
文献类型：
--
作者：
Farhan, Maikel A.;Carmine-Simmen, Katia;Murray, Allan G.
肿瘤新生血管的形成是通过抑制血管内皮生长因子（VEGF）或受体来阻止肿瘤生长，但对血管生成抑制的耐药性限制了临床疗效。抑制磷酸肌醇 3 激酶途径中间体、哺乳动物雷帕霉素靶点 (mTOR) 也能抑制肿瘤生长，并可能防止 VEGF 受体抑制剂的逃逸。 mTOR 被组装成两个独立的多分子复合物：mTORC1 和 mTORC2。 mTORC2 抑制对内皮和肿瘤血管生成的直接影响尚不清楚。我们使用药理学抑制剂和 RNA 干扰来确定 mTORC2 与 Akt1 和 mTORC1 在人内皮细胞 (EC) 中的功能。研究了血管生成、内皮细胞迁移、细胞骨架重组和调节基质粘附的信号事件。 mTORC1 活性的持续失活上调了 mTORC2 依赖性 Akt1 激活。反过来，暴露于 mTORC1 抑制的 ECs 对细胞凋亡具有抵抗力，并且在抑制解除后对肾细胞癌 (RCC) 刺激的血管生成高度敏感。相反，mTORC1/2 双重抑制或选择性 mTORC2 失活抑制了 RCC 细胞和 VEGF 的血管生成。 mTORC2 失活比 Akt1 或 mTORC1 失活更能减少 EC 迁移。从机制上讲，mTORC2 失活可强烈抑制 VEGF 刺激的 EC 肌动蛋白聚合，并抑制粘着斑形成和粘着斑激酶激活，不依赖于 Akt1。内皮 mTORC2 部分通过调节 EC 粘着斑激酶活性、基质粘附和细胞骨架重塑来调节血管生成，不依赖于 Akt/mTORC1。
Tumor neovascularization is targeted by inhibition of vascular endothelial growth factor (VEGF) or the receptor to prevent tumor growth, but drug resistance to angiogenesis inhibition limits clinical efficacy. Inhibition of the phosphoinositide 3 kinase pathway intermediate, mammalian target of rapamycin (mTOR), also inhibits tumor growth and may prevent escape from VEGF receptor inhibitors. mTOR is assembled into two separate multi-molecular complexes, mTORC1 and mTORC2. The direct effect of mTORC2 inhibition on the endothelium and tumor angiogenesis is poorly defined. We used pharmacological inhibitors and RNA interference to determine the function of mTORC2 versus Akt1 and mTORC1 in human endothelial cells (EC). Angiogenic sprouting, EC migration, cytoskeleton re-organization, and signaling events regulating matrix adhesion were studied. Sustained inactivation of mTORC1 activity up-regulated mTORC2-dependent Akt1 activation. In turn, ECs exposed to mTORC1-inhibition were resistant to apoptosis and hyper-responsive to renal cell carcinoma (RCC)-stimulated angiogenesis after relief of the inhibition. Conversely, mTORC1/2 dual inhibition or selective mTORC2 inactivation inhibited angiogenesis in response to RCC cells and VEGF. mTORC2-inactivation decreased EC migration more than Akt1- or mTORC1-inactivation. Mechanistically, mTORC2 inactivation robustly suppressed VEGF-stimulated EC actin polymerization, and inhibited focal adhesion formation and activation of focal adhesion kinase, independent of Akt1. Endothelial mTORC2 regulates angiogenesis, in part by regulation of EC focal adhesion kinase activity, matrix adhesion, and cytoskeletal remodeling, independent of Akt/mTORC1.