Human oral squamous cell carcinoma cell lines promote angiogenesis via expression of vascular endothelial growth factor and upregulation of KDR/flk-1 expression in endothelial cells.

Angiogenesis is an important phenomenon for the growth and metastasis of solid tumors. The present study examined the characterization of angiogenic factors produced by human oral squamous cell carcinoma (oral SCC) cell lines established from lymph node metastatic tumors and primary tumor in different patients. The conditioned medium of HSC3 with the strongest metastatic ability among the examined lines enhanced a tube-forming activity of bovine carotid artery endothelial (BAE) cells in collagen gel cultures. The treatment of HSC3 with anti-vascular endothelial growth factor (VEGF) antibody or anti-basic fibroblast growth factor (bFGF) antibody, either alone or in combination, attenuated the activity of urokinase-type plasminogen activator (uPA) in the endothelial cells stimulated by the conditioned medium of HSC3. In contrast, neither anti-interleukin-8 (IL-8) antibody nor anti-hepatocyte growth factor (HGF beta) antibody affected uPA activity in the endothelial cells. Among these HSC cell lines, HSC3 secreted VEGF with the highest (1.92 +/- 0.24 ng/10(6) cells/24 h) level and bFGF. The level of bFGF secreted by HSC3 was lower than that secreted by BAE cells. Other oral SCC cell lines secreted lower levels of VEGF and undetectable levels of bFGF. By reverse transcriptase-polymerase chain reaction analysis of mRNA the production of VEGF121, VEGF145, VEGF165, VEGF189, and VEGF206 in these cell lines was able to be detected. Moreover, the conditioned medium of HSC3 enhanced the tyrosine phosphorylation and expression of kinase insert domain-containing receptor (KDR/flk-1) in the endothelial cells. These results suggest that oral SCC promotes angiogenesis via expression of VEGF and upregulation of their receptor KDR/flk-1 expression in endothelial cells.