Tumor-induced endothelial cell activation:: role of vascular endothelial growth factor
Tumor-induced endothelial cell activation:: role of vascular endothelial growth factor
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DOI：
10.1152/ajpcell.00306.2003
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发表时间：
2004-05-01
影响因子：
5.5
通讯作者：
Caramelo, C
中科院分区：
文献类型：
--
作者：
Castilla, MA;Neria, F;Caramelo, C
肿瘤的促血管生成、增殖作用广泛存在于融合内皮细胞(EC)中，但在融合的、接触抑制的EC中尚缺乏。本研究观察了恶性成骨细胞系MG63的肿瘤条件培养液(CM)对单层静止的牛主动脉内皮细胞的影响。MG63-CM和MG63-CM+CoCl2可显著提高血清缺乏条件下内皮细胞的存活率，而不诱导内皮细胞增殖。此外，高表达血管内皮细胞生长因子的MG63-CM和MG63-CM+CoCl2均可诱导EC发生相应的表型变化，包括核仁/染色质浓缩、核浆比、毛细血管样空泡结构、血管样无细胞区域、基质迁移、补种生长优势和因子含量增加。这些作用均被血管内皮生长因子及其受体(VEGFR2)阻断剂显著抑制。尤其重要的是，在人类微血管内皮细胞系(HMEC)中检测到了一组类似的效应。在基因表达方面，与MG63-CM孵育后，内皮细胞内源性VEGFR2mRNA和蛋白表达减弱，而VEGFR2mRNA表达明显增加。在机制上，MG63-CM激活蛋白激酶B(PKB)/Akt，p44/p42-丝裂原活化蛋白激酶(MAPK)途径，抑制和磷酸化实验都表明。总之，肿瘤细胞激活融合的、静止的EC，促进生存、表型和基因表达的变化。重要的是，血管内皮生长因子拮抗剂将MG63-CM从保护作用转变为EC损伤作用。
Proangiogenic, proliferative effects of tumors have been extensively characterized in subconfluent endothelial cells (EC), but results in confluent, contact-inhibited EC are critically lacking. The present study examined the effect of tumor-conditioned medium (CM) of the malignant osteoblastic cell line MG63 on monolayer, quiescent bovine aorta EC. MG63-CM and MG63-CM + CoCl2 significantly increased EC survival in serum-starved conditions, without inducing EC proliferation. Furthermore, MG63-CM and MG63-CM + CoCl2, both containing high amounts of vascular endothelial growth factor (VEGF), induced relevant phenotypic changes in EC (all P < 0.01) involving increase of nucleoli/chromatin condensations, nucleus-to-cytosol ratio, capillary-like vacuolated structures, vessel-like acellular areas, migration through Matrigel, growth advantage in reseeding, and factor VIII content. All these actions were significantly inhibited by VEGF and VEGF receptor (VEGFR2) blockade. Of particular importance, a set of similar effects were detected in a human microvascular endothelial cell line (HMEC). With regard to gene expression, incubation with MG63-CM abolished endogenous VEGF mRNA and protein but induced a clear-cut increase in VEGFR2 mRNA expression in EC. In terms of mechanism, MG63-CM activates protein kinase B (PKB)/Akt, p44/p42-mitogen-activated protein kinase (MAPK)-mediated pathways, as suggested by both inhibition and phosphorylation experiments. In conclusion, tumor cells activate confluent, quiescent EC, promoting survival, phenotypic, and gene expression changes. Of importance, VEGF antagonism converts MG63-CM from protective to EC-damaging effects.