Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing 211166, China.
Cancer Biol Med. 2020 Feb 15;17(1):88-100. doi: 10.20892/j.issn.2095-3941.2019.0262.
The endothelial to mesenchymal transition (EndMT) plays a major role in cancer metastasis by regulating the complexity of the tumor microenvironment (TME). Here, we investigated whether 27-hydroxycholesterol (27HC) induces EndMT in endothelial cells (ECs). EndMT markers in the human microvascular endothelial cell-1 (HMEC-1) cell line and human umbilical vein endothelial cells (HUVECs) stimulated with 27HC were evaluated with Western blot. Epithelial to mesenchymal transition (EMT) markers in breast cancer (BC) cells cultured in conditioned medium were investigated with quantitative real time polymerase chain reaction (qRT-PCR). The MMP-2 and MMP-9 mRNA expression and activity were detected with qRT-PCR and gelatin zymography assays, respectively. The effect of activated STAT3 on 27HC-induced EndMT was validated by Western blot, immunofluorescence staining, and cell transfection assays. The migration ability of BC cells was evaluated with Transwell assays. We found that 27HC induced EndMT in HMEC-1 and HUVECs, and 27HC-induced EndMT facilitated EMT and BC cell migration. The 27HC-induced EMT of BC cells also promoted EndMT and HUVEC migration. Investigation of the underlying molecular mechanisms revealed that STAT3 knockdown repressed EndMT in HUVECs as well as migration in BC cells induced with 27HC. In addition, C646 and resveratrol, inhibitors of STAT3 acetylation, repressed the expression of Ac-STAT3, p-STAT3, and EndMT markers in HUVECs exposed to 27HC; these HUVECs in turn attenuated the migration ability of BC cells in 27HC-induced EndMT. Cross-talk between 27HC-induced EndMT and EMT was observed in the TME. Moreover, activation of STAT3 signaling was found to be involved in 27HC-induced EndMT.
内皮细胞向间充质细胞转化（EndMT）在调节肿瘤微环境（TME）的复杂性方面在癌症转移中起着重要作用。在这里，我们研究了 27-羟胆固醇（27HC）是否会诱导内皮细胞（ECs）发生 EndMT。通过 Western blot 评估了 27HC 刺激下人微血管内皮细胞-1（HMEC-1）细胞系和人脐静脉内皮细胞（HUVECs）中的 EndMT 标志物。通过定量实时聚合酶链反应（qRT-PCR）研究了在条件培养基中培养的乳腺癌（BC）细胞中的上皮间质转化（EMT）标志物。通过 qRT-PCR 和明胶酶谱测定分别检测 MMP-2 和 MMP-9 mRNA 表达和活性。通过 Western blot、免疫荧光染色和细胞转染实验验证了激活的 STAT3 对 27HC 诱导的 EndMT 的影响。通过 Transwell 测定评估了 BC 细胞的迁移能力。我们发现 27HC 诱导 HMEC-1 和 HUVEC 发生 EndMT，并且 27HC 诱导的 EndMT 促进了 EMT 和 BC 细胞迁移。BC 细胞的 27HC 诱导的 EMT 也促进了 EndMT 和 HUVEC 迁移。对潜在分子机制的研究表明，STAT3 敲低抑制了 HUVEC 中的 EndMT 以及 27HC 诱导的 BC 细胞的迁移。此外，STAT3 乙酰化抑制剂 C646 和白藜芦醇抑制了暴露于 27HC 的 HUVEC 中 Ac-STAT3、p-STAT3 和 EndMT 标志物的表达；这些 HUVEC 反过来又减弱了 27HC 诱导的 EndMT 中 BC 细胞的迁移能力。在 TME 中观察到 27HC 诱导的 EndMT 和 EMT 之间的串扰。此外，发现 STAT3 信号的激活参与了 27HC 诱导的 EndMT。
