Antiangiogenic therapy has increasingly become an important strategy for the treatment of colorectal cancer. Recent studies have shown that the tumour microenvironment (TME) promotes tumour angiogenesis. Bufalin is an active antitumour compound whose efficacy has been indicated by previous studies. However, there are very few studies on the antiangiogenic effects of bufalin. Herein, human umbilical vein endothelial cell (HUVEC) tube formation, migration and adhesion tests were used to assess angiogenesis in vitro. Western blotting and quantitative PCR were used to detect relevant protein levels and mRNA expression levels. A subcutaneous xenograft tumour model and a hepatic metastasis model were established in mice to investigate the influence of bufalin on angiogenesis mediated by the TME in vivo. We found that angiogenesis mediated by cells in the TME was significantly inhibited in the presence of bufalin. The results demonstrated that the proangiogenic genes in HUVECs, such as VEGF, PDGFA, E-selectin and P-selectin, were downregulated by bufalin and that this downregulation was mediated by inhibition of the STAT3 pathway. Overexpression of STAT3 reversed the inhibitory effects of bufalin on angiogenesis. Furthermore, there was little reduction in angiogenesis when bufalin directly acted on the cells in the tumour microenvironment. Our findings demonstrate that bufalin suppresses tumour microenvironment-mediated angiogenesis by inhibiting the STAT3 signalling pathway in vascular endothelial cells, revealing that bufalin may be used as a new antiangiogenic adjuvant therapy medicine to treat colorectal cancer.

中文翻译：

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蟾毒灵通过抑制 STAT3 信号通路抑制肿瘤微环境介导的血管生成

抗血管生成治疗日益成为结直肠癌治疗的重要策略。最近的研究表明，肿瘤微环境（TME）促进肿瘤血管生成。蟾蜍灵是一种活性抗肿瘤化合物，其功效已被先前的研究所证实。然而，关于蟾蜍灵的抗血管生成作用的研究却很少。在此，使用人脐静脉内皮细胞（HUVEC）管形成、迁移和粘附测试来评估体外血管生成。采用Western blotting和定量PCR检测相关蛋白水平和mRNA表达水平。建立小鼠皮下异种移植肿瘤模型和肝转移模型，研究蟾蜍灵对体内TME介导的血管生成的影响。我们发现，蟾毒灵存在时，TME 中细胞介导的血管生成受到显着抑制。结果表明，蟾蜍灵可下调 HUVEC 中的促血管生成基因，例如 VEGF、PDGFA、E-选择素和 P-选择素，并且这种下调是通过抑制 STAT3 通路介导的。STAT3 的过度表达逆转了蟾蜍灵对血管生成的抑制作用。此外，当蟾毒灵直接作用于肿瘤微环境中的细胞时，血管生成几乎没有减少。我们的研究结果表明，蟾蜍灵通过抑制血管内皮细胞中的STAT3信号通路来抑制肿瘤微环境介导的血管生成，揭示蟾蜍灵可能作为一种新的抗血管生成辅助治疗药物来治疗结直肠癌。