Expression of angiogenesis-related genes regulates different steps in the process of tumor growth and metastasis in human urothelial cell carcinoma of the urinary bladder

Objective: This study was designed to determine the relative activity of angiogenesis-related genes in the regulation of tumorigenicity and subsequent metastases of urothelial cell carcinomas (UC) of the urinary bladder.

Methods: We selected the clones with the highest and lowest expression level of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF)/vascular permeability factor or interleukin-8 (IL-8) in the highly tumorigenic and metastatic human UC cell line 253J B-V. Tumorigenicity and production of spontaneous lymph node metastases were evaluated 1, 2, 4, 8 and 12 weeks after orthotopic implantation of each specific expression clone into the urinary bladder of athymic nude mice. Moreover, the transitional changes in the expression of angiogenesis-related genes and neovascularization were determined in tumors and metastases.

Results: At the early stage of tumor growth following orthotopic implantation, tumorigenicity and metastases were significantly increased in the clones with the highest expression of bFGF and IL-8, while they were significantly inhibited in the clones with the lowest expression of bFGF and IL-8 compared to parental 253J B-V. In the tumors, specific expression of angiogenesis-related genes and intratumor neovascularity of each clone were gradually regulated to the same level as parental 253J B-V. In metastasized tumors of the highest and lowest IL-8-expressing clones, IL-8 expression was consistently high and low, respectively.

Conclusions: These findings indicate that at the early stage of tumor growth, bFGF and IL-8 expression play important roles in the regulation of angiogenesis, tumorigenicity and subsequent metastases of human bladder cancer.