Instituto de Inmunología, Universidad Austral de Chile, Valdivia 5110566, Chile.
Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile.
Carcinogenesis. 2019 Apr 29;40(2):313-323. doi: 10.1093/carcin/bgz002.
The permeability of endothelial cells is regulated by the stability of the adherens junctions, which is highly sensitive to kinase-mediated phosphorylation and endothelial nitric oxide synthase (eNOS)-mediated S-nitrosylation of its protein components. Solid tumors can produce a variety of factors that stimulate these signaling pathways leading to endothelial cell hyperpermeability. This generates stromal conditions that facilitate tumoral growth and dissemination. Galectin-8 (Gal-8) is overexpressed in several carcinomas and has a variety of cellular effects that can contribute to tumor pathogenicity, including angiogenesis. Here we explored whether Gal-8 has also a role in endothelial permeability. We show that recombinant Gal-8 activates eNOS, induces S-nitrosylation of p120-catenin (p120) and dissociation of adherens junction, leading to hyperpermeability of the human endothelial cell line EAhy926. This pathway involves focal-adhesion kinase (FAK) activation downstream of eNOS as a requirement for eNOS-mediated p120 S-nitrosylation. This suggests a reciprocal, yet little understood, regulation of phosphorylation and S-nitrosylation events acting upon adherens junction permeability. In addition, glutathione S-transferase (GST)-Gal-8 pull-down experiments and function-blocking β1-integrin antibodies point to β1-integrins as cell surface components involved in Gal-8-induced hyperpermeability. Endogenous Gal-8 secreted from the breast cancer cell line MCF-7 has similar hyperpermeability and signaling effects. Furthermore, the mouse cremaster model system showed that Gal-8 also activates eNOS, induces S-nitrosylation of adherens junction components and is an effective hyperpermeability agent in vivo. These results add endothelial permeability regulation by S-nitrosylation as a new function of Gal-8 that can potentially contribute to the pathogenicity of tumors overexpressing this lectin.
内皮细胞的通透性受黏附连接的稳定性调节，而黏附连接的稳定性对蛋白成分的激酶介导磷酸化和内皮型一氧化氮合酶（eNOS）介导的 S-亚硝基化极为敏感。实体瘤可产生多种刺激这些信号通路的因子，导致内皮细胞通透性增加。这会产生促进肿瘤生长和扩散的基质条件。半乳糖凝集素-8（Gal-8）在几种癌中过度表达，具有多种可导致肿瘤发病机制的细胞效应，包括血管生成。在这里，我们探讨了 Gal-8 是否也在血管内皮通透性中发挥作用。我们发现重组 Gal-8 激活 eNOS，诱导 p120-连环蛋白（p120）的 S-亚硝基化和黏附连接的解离，导致人内皮细胞系 EAhy926 的通透性增加。该途径涉及 eNOS 下游的焦点黏附激酶（FAK）激活，是 eNOS 介导的 p120 S-亚硝基化所必需的。这表明黏附连接通透性的磷酸化和 S-亚硝基化事件的调节是相互的，但了解甚少。此外，谷胱甘肽 S-转移酶（GST）-Gal-8 下拉实验和功能阻断β1-整合素抗体表明β1-整合素是 Gal-8 诱导的通透性增加涉及的细胞表面成分。从乳腺癌细胞系 MCF-7 分泌的内源性 Gal-8 具有类似的通透性和信号转导作用。此外，鼠标提睾肌模型系统表明 Gal-8 还能激活 eNOS，诱导黏附连接成分的 S-亚硝基化，并且是体内有效的通透性增加剂。这些结果将 S-亚硝基化调节内皮通透性添加为 Gal-8 的新功能，这可能有助于过度表达这种凝集素的肿瘤的发病机制。
