Importance of vascular phenotype by basic fibroblast growth factor, and influence of the angiogenic factors basic fibroblast growth factor/fibroblast growth factor receptor-1 and ephrin-A1/EphA2 on melanoma progression

Abstract

The expression of several angiogenic factors and receptors was examined in a series of vertical growth phase cutaneous melanomas using high-throughput tissue microarray technology and immunohistochemistry. The results were correlated with microvessel density, clinicopathological features, and patient survival. Expression of basic fibroblast growth factor (bFGF) was significantly associated with increased microvessel density. Also, we found an independent prognostic importance of vascular phenotype by endothelial cell expression of bFGF; cases with positive vessels had the best prognosis and these tumors revealed a low frequency of vascular invasion (14%) when compared with bFGF-negative vessels (47%). This bFGF-negative phenotype was significantly increased in metastatic lesions. Strong tumor cell expression of FLT-4, ephrin-A1, and EphA2 was associated with increased melanoma thickness, and ephrin-A1 staining was related to decreased survival (P = 0.039). Expression of EphA2 in tumor cells was associated with increased tumor cell proliferation (Ki-67 positivity), indicating possible autocrine growth stimulation. Thus, our findings indicate the presence of phenotypic diversity among tumor-associated vessels, and subgroups defined by bFGF expression may be of clinical importance. bFGF was associated with microvessel density, whereas the ephrin-A1/EphA2 pathway might also be important for tumor cell proliferation and patient survival.

Figure 1.

Immunohistochemical staining pattern of VEGF-C (a), VEGF-C receptor FLT-4 (b), bFGF in tumor cells (c), and bFGF in tumor-associated endothelial cells (d); inset, double staining of bFGF (Fast Blue) and Factor-VIII (3-amino-9-ethylcarbazole, red) in tumor-associated endothelial cells, FGFR-1 (e), interleukin-8 (f), ephrin-A1 (g), and ephrin receptor EphA2 (h). Original magnifications, ∼×400.

Figure 2.

The correlation between ephrin-A1 and MVD in subgroups according to median tumor thickness. *, The difference is statistically significant (Mann-Whitney, P = 0.013).

Figure 3.

Survival curves were estimated according to the Kaplan-Meier method with death because of melanoma as end point. A: Survival by bFGF expression in tumor-associated endothelial cells. B: Survival by combinations of vascular phenotype by bFGF expression and MVD (MVD+, MVD >67th percentile; MVD−, MVD ≤67th percentile). C: Survival by ephrin-A1 expression.