Hypoxia-induced angiogenesis of cultured human salivary gland carcinoma cells enhances vascular endothelial growth factor production and basic fibroblast growth factor release

The angiogenic activity of two human salivary gland tumor cell lines, ACCS from adenoid cystic carcinoma and IT-2 from mucoepidermoid carcinoma, was e xamined by stimulating tube formation by bovine capillary endothelial cells (BCE). ACCS and IT-2 were cultured in 20 or 3% oxygen, representing normox ic and hypoxic conditions. respectively, and conditioned medium (CM) was ob tained from each culture. The BCE tubes stimulated by hypoxic CM were 1.59 (ACCS) and 1.42 (IT-2) times longer than those stimulated by normoxic CM. T he tube-forming activity of CM was inhibited by preincubation with either a nti-vascular endothelial growth factor (VEGF) Ige or anti-basic fibroblast growth factor (bFGF) IgG, suggesting that both VEGF and bFGF with angiogeni c activity were present in the CM. This was confirmed by ELISA, which also demonstrated increased concentrations of both proteins in the hypoxic CM. N orthern blot analysis showed an increased VEGF mRNA level in both carcinoma cells with hypoxia, while hypoxia did not affect the bFGF mRNA level in ei ther cell line. The results suggest that both VEGF and bFGF are major angio genesis factors in salivary gland tumors, and hypoxia-induced angiogenesis results from upregulation of VEGF and increased release of bFGF. (C) 2001 E lsevier Science Ltd. All rights reserved.