VEGF通过激活ERK/MAPK通路促进三阴性乳腺癌肿瘤干细胞的形成

目的 探讨血管内皮生长因子（VEGF）对三阴性乳腺癌肿瘤干细胞的调控作用并探索其作用机制。方法 通过Oncomine数据库、UALCAN数据库及Human Protein Atlas数据库分别验证VEGF在乳腺癌中的表达情况，分析VEGF表达与不同分子亚型的关系，利用在线数据库分析VEGF的表达情况与乳腺癌预后的关系。选取三阴性乳腺癌MDA-MB-231细胞，加入外源性hVEGF165通过体外微球形成实验观察体外成球能力，并利用Western blot、RT-qPCR等方法检测肿瘤干细胞相关标志物CD44、c-Myc、Nanog、ALDH1的表达以及相关通路的激活情况。结果 利用Oncomine、UALCAN、HPA数据库分析显示，VEGF在乳腺癌中表达较癌旁组织增高（P<0.0001），其表达与分子亚型相关，三阴性乳腺癌中VEGF表达显著升高。Kaplan-Meier Plotter数据库分析结果提示高表达VEGF的乳腺癌患者预后更差，总生存期OS缩短，差异具有统计学意义（P<0.0001）。与VEGF低表达患者相比，VEGF高表达的乳腺癌患者无进展生存期、无远处转移生存期以及复发后生存期均显著缩短，差异具有统计学意义（P<0.0001）。体外实验发现加入外源性的hVEGF165后三阴性乳腺癌MDA-MB-231细胞的成球能力显著增强，差异具有统计学意义（P=0.0029）。Western blotting、RT-qPCR结果表明乳腺癌MDA-MB-231微球体中VEGF/NRP-1及肿瘤干细胞相关标志物CD44、Nanog、c-Myc的表达量显著升高。加入外源性的hVEGF165促进了肿瘤干细胞相关标志物CD44、c-Myc、Nanog及ALDH1的表达，而CD24的表达量则显著下降，上述作用具有时间依赖性。Western blotting实验提示加入外源性的hVEGF165能够激活三阴性乳腺癌细胞ERK/MAPK通路。 结论 VEGF可能通过激活ERK/MAPK通路促进了三阴性乳腺癌肿瘤干细胞的形成。

Vascular endothelial growth factor promotes cancer stemness of triple-negative breast cancer via MAPK/ERK pathway

Objective To investigate the role of vascular endothelial growth factor (VEGF) in regulating triple-negative breast cancer (TNBC) stem cells and the possible pathways involved in this regulatory mechanism. Methods The Oncomine database, UALCAN database and Human Protein Atlas (HPA) database were used to analyze the expression of VEGF in breast cancer and its association with the molecular subtypes and prognosis of breast cancer. Sphere formation assay was carried out to examine the effects of hVEGF165 on sphere formation ability of TNBC MDA-MB-231 cell line; Western blotting and RT-qPCR were performed to detect the expression of the tumor stem cell markers including CD44, c-Myc, Nanog, and ALDH1 and the activation of the related pathways. Results Data from the online databases all showed a significant increase of VEGF expression in breast cancer tissues than in the adjacent tissues (P<0.0001), and its expression level was associated with the molecular subtypes of breast cancer. Specifically, the expression of VEGF was markedly higher in TNBC than in other subtypes of breast cancer. Survival analysis showed that breast cancer patients with a high VEGF expression had a significantly shortened overall survival (P<0.0001). In the cell experiments, the sphere formation ability of MDA-MB-231 cells was significantly enhanced after treatment with hVEGF165 (P=0.0029). Compared with the monolayer cells, MDA-MB-231 spheres showed significantly increased expressions of VEGF, NRP-1, CD44, Nanog and c-Myc. Treatment with hVEGF165 resulted in significant time-dependent up-regulation of the expressions of CD44, c-Myc, Nanog and ALDH1 and down-regulation of CD24 expression in the cells. The results of Western blotting demonstrated that treatment with hVEGF165 caused significant activation of the ERK/MAPK pathway in MDA-MB-231 cells. Conclusion VEGF promotes cancer stemness of triple-negative breast cancer possibly through the ERK/MAPK pathway.