VEGF, bFGF and EGF in the angiogenesis of human melanoma xenografts.

Vascular endothelial growth factor (VEGF) is a major inducer of angiogenesis in tumors. Basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) have both been shown to interact with VEGF. The involvement of VEGF, bFGF, and EGF in melanoma angiogenesis was investigated here. Four human melanoma cell lines (A-07, D-12, R-18, U-25) were included in the study. Angiogenesis was quantified by scoring of tumor-oriented capillaries following intradermal cell inoculation in BALB/c nu/nu mice. VEGF, bFGF and EGF expression and secretion were investigated by Western blotting and enzyme-linked immunosorbent assay, respectively. Immunohistochemistry of xenografts grown intradermally was used to reveal VEGF and bFGF localization in vivo. The rate of angiogenesis differed substantially among the melanoma lines; the sequence from a high to low rate of angiogenesis was: A-07, D-12, R-18, U-25. A-07, which induced the highest rate of angiogenesis, showed a higher rate of VEGF secretion, stronger VEGF staining by immunohistochemistry and higher bFGF expression than the other lines. U-25, which induced the lowest rate of angiogenesis, showed a higher rate of VEGF secretion than D-12 and R-18. A-07 was the only line that showed detectable bFGF secretion, and R-18 was the only line that showed detectable EGF secretion. VEGF is probably important in the angiogenesis of melanomas. However, heterogeneity in rate of angiogenesis among melanomas cannot be attributed to heterogeneity in rate of secretion of VEGF, bFGF and/or EGF only.