1INSERM U866, Faculty of Medecine, 7 Blvd. Jeanne d'Arc, 21000 Dijon Cedex, France.
FASEB J. 2013 Oct;27(10):4169-83. doi: 10.1096/fj.12-226977. Epub 2013 Jun 26.
The heat-shock protein 27 (HSP27) is up-regulated in tumor cells and released in their microenvironment. Here, we show that extracellular HSP27 has a proangiogenic effect evidenced on chick chorioallantoic membrane. To explore this effect, we test the recombinant human protein (rhHSP27) at physiopathological doses (0.1-10 μg/ml) onto human microvascular endothelial cells (HMECs) grown as monolayers or spheroids. When added onto HMECs, rhHSP27 dose-dependently accelerates cell migration (with a peak at 5 μg/ml) and favors spheroid sprouting within 12-24 h. rhHSP27 increases VEGF gene transcription and promotes secretion of VEGF-activating VEGF receptor type 2. Increased VEGF transcription is related to NF-κB activation in 30 min. All of these effects are initiated by rhHSP27 interaction with Toll-like receptor 3 (TLR3). Such an interaction can be detected by immunoprecipitation but does not seem to be direct, as we failed to detect an interaction between rhHSP27 and monomeric TLR3 by SPR analysis. rhHSP27 is rapidly internalized with a pool of TLR3 to the endosomal compartment (within 15-30 min), which is required for NF-κB activation in a cytosolic Ca(2+)-dependent manner. The HSP27/TLR3 interaction induces NF-κB activation, leading to VEGF-mediated cell migration and angiogenesis. Such a pathway provides alternative targets for antiangiogenic cancer therapy.
热休克蛋白 27（HSP27）在肿瘤细胞中上调，并在其微环境中释放。在这里，我们表明细胞外 HSP27 具有促血管生成作用，这在鸡胚绒毛尿囊膜上得到了证明。为了探索这种作用，我们在单层或球体生长的人微血管内皮细胞（HMEC）上测试了生理病理剂量（0.1-10μg/ml）的重组人蛋白（rhHSP27）。当添加到 HMEC 上时，rhHSP27 剂量依赖性地加速细胞迁移（在 5μg/ml 时达到峰值），并在 12-24 小时内有利于球体发芽。rhHSP27 增加 VEGF 基因转录并促进激活 VEGF 受体类型 2 的 VEGF 分泌。VEGF 转录的增加与 NF-κB 在 30 分钟内的激活有关。所有这些效应都是由 rhHSP27 与 Toll 样受体 3（TLR3）相互作用引发的。这种相互作用可以通过免疫沉淀检测到，但似乎不是直接的，因为我们未能通过 SPR 分析检测到 rhHSP27 与单体 TLR3 之间的相互作用。rhHSP27 与 TLR3 一起被快速内化到内体区室（在 15-30 分钟内），这对于 NF-κB 的激活是必需的，NF-κB 的激活是通过细胞质 Ca（2+）依赖性方式进行的。HSP27/TLR3 相互作用诱导 NF-κB 激活，导致 VEGF 介导的细胞迁移和血管生成。这种途径为抗血管生成癌症治疗提供了替代靶点。
