Heath-Engel Hannah M, Lingwood Clifford A
Division of Infection, Immunity, Injury and Repair, Department of Pediatric Laboratory Medicine, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.
Angiogenesis. 2003;6(2):129-41. doi: 10.1023/B:AGEN.0000011799.47529.fd.
Binding of verotoxin 1 (VT1) via its receptor (globotriaosylceramide/Gb3) to both endothelial and tumour cell subsets suggests that VT1 may have both antineoplastic and antiangiogenic potential. We investigated this potential using the ECV304 cell line, which, although identified as a bladder carcinoma cell line, displays some endothelial characteristics, including tubule formation (differentiation) following appropriate stimulation. Differentiated ECV304 cells retained Gb3 expression/VT1 sensitivity. VT1 internalization and retrograde transport through the Golgi to the ER was observed. ECV304 xenografts in immunocompromised mice were invasive but surprisingly poorly vascularized. Intratumoural VT1 injection significantly reduced ECV304 xenograft growth and enhanced mouse survival. Gb3 expression was decreased in residual tumour, likely due to cell cycle arrest. Untreated ECV304 xenograft sections bound VT1 throughout the tumour. Anti-von Willebrand factor (vWF) antibody staining for neovasculature showed only morphologically atypical, indistinct structures, unlabelled by VT1. Human bladder carcinoma samples were, in contrast, highly vascular and blood vessels were 100% co-labelled by anti-vWF antibody and VT1, with no extravascular staining. These results suggest that ECV304 xenografts are not characteristic of bladder carcinoma in terms of Gb3 expression, and that VT1 staining may provide a new reliable index of tumour neovasculature. We conclude that ECV304 cells are not an appropriate in vivo model of either tumour angiogenesis or bladder carcinoma. These studies, nevertheless, further demonstrate the in vivo antineoplastic and antiangiogenic potential of VT1, and show that Gb3 is expressed in cells undergoing in vitro 'vascular' differentiation, and in the neovasculature of human bladder carcinomas.
维罗毒素1（VT1）通过其受体（球三糖神经酰胺/Gb3）与内皮细胞和肿瘤细胞亚群结合，这表明VT1可能具有抗肿瘤和抗血管生成的潜力。我们使用ECV304细胞系研究了这种潜力，该细胞系虽然被鉴定为膀胱癌细胞系，但具有一些内皮细胞特征，包括在适当刺激后形成小管（分化）。分化后的ECV304细胞保留了Gb3表达/VT1敏感性。观察到VT1内化并通过高尔基体逆行转运至内质网。免疫缺陷小鼠体内的ECV304异种移植物具有侵袭性，但血管化程度出人意料地低。瘤内注射VT1可显著降低ECV304异种移植物的生长并提高小鼠存活率。残余肿瘤中Gb3表达降低，可能是由于细胞周期停滞。未经处理的ECV304异种移植物切片在整个肿瘤中均与VT1结合。针对新生血管的抗血管性血友病因子（vWF）抗体染色仅显示形态上不典型、不清晰的结构，未被VT1标记。相比之下，人膀胱癌样本血管丰富，血管100%被抗vWF抗体和VT1共同标记，无血管外染色。这些结果表明，就Gb3表达而言，ECV304异种移植物并非膀胱癌的典型特征，且VT1染色可能为肿瘤新生血管提供一个新的可靠指标。我们得出结论，ECV3G细胞不是肿瘤血管生成或膀胱癌的合适体内模型。然而，这些研究进一步证明了VT1在体内的抗肿瘤和抗血管生成潜力，并表明Gb3在经历体外“血管”分化的细胞以及人膀胱癌的新生血管中表达。
