Heparin-binding growth factor(s) derived from head and neck squamous cell carcinomas induce endothelial cell proliferations.

BACKGROUND: Tumor growth is dependent on the expansion and proliferation of the host vascular system into the primary neoplasm (angiogenesis). The development of an intact vascular system requires migration and proliferation of endothelial cells and assembly into microvessels. Previous studies in our laboratory demonstrated that head and neck squamous cell carcinomas (HNSCC) are angiogenic in vivo. To clarify the mechanism of HNSCC-induced angiogenesis, the present study sought to determine if HNSCCs produced endothelial cell mitogens in vitro. METHODS: Production of PGE-2, TGF-beta, FGF-2 (basic-FGF [fibroblast growth factor]), and vascular endothelial cell growth factor (VEGF) were quantitated by enzyme-linked immunoabsorbant assay (ELISA) in five HNSCC lines. Cell free supernatants of 5 HNSCC lines were tested in a nonradioactive proliferation assay using human umbilical vein endothelial cells (HUVECs). RESULTS: All lines demonstrated enhanced endothelial cell proliferation in a dose-dependent fashion. Fractionation of these supernatants by heparin column chromatography significantly reduced endothelial cell proliferation in the five lines tested (range, 31.7% to 46.23% reduction; mean, 38.14+/-6.02%). Pretreatment with antibody to VEGF but not transforming growth factor (TGF)-beta inhibited endothelial cell proliferation. CONCLUSIONS: These studies indicate HNSCCs produce factor(s) which stimulate endothelial cell proliferation and that VEGF may be involved in HNSCC-induced endothelial cell mitogenesis.

Regulation of the steps of angiogenesis by human head and neck squamous cell carcinomas.

Human head and neck squamous cell carcinoma (HNSCC) cell cultures were established to identify the angiogenic factors they produced and how these factors contribute to two steps of the angiogenic process: endothelial cell proliferation and migration. The HNSCC cells secreted vascular endothelial cell growth factor (VEGF), transforming growth factor-beta (TGF-beta) and prostaglandin E2 (PGE2), but only low levels of basic fibroblast growth factor. Both proliferation-stimulatory and -inhibitory cytokines were produced by the HNSCC cells, with VEGF promoting endothelial cell proliferation, prostaglandins having no effect and TGF-beta downregulating proliferation. Two methods were used to measure endothelial cell migration: migration into a wound in the endothelial cell monolayer and migration across a filter into lower compartments. HNSCC cell supernatants stimulated endothelial cell migration in both migration models. VEGF had no effect on the motility of endothelial cells. However, when TGF-beta activity in the HNSCC supernatants was neutralized with antibody or the production of prostaglandins by HNSCC cells was blocked with indomethacin, the migration-stimulatory activity in the HNSCC cell supernatants was diminished. Adding authentic PGE2 or TGF-beta 1 to endothelial cells mimicked the migration-stimulatory activity of the HNSCC supernatants. Thus, HNSCC-derived VEGF is important in stimulating endothelial cell proliferation, while the antiproliferative effect of TGF-beta and the migration-stimulatory activity of TGF-beta and PGE2 suggest their having a role in the morphogenic processes of angiogenesis.