Departments of Ostetrics and Gynecology and Molecular Genetics, The University of Illinois at Chicago, Chicago, Illinois 60612, USA
Abstract
We investigated the effects of vascular endothelial growth factor (VEGF) on cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) synthesis in human microvascular endothelial cells (HMEC-1). Treatment of HMEC-1 with VEGF resulted in a dose- and time-dependent up-regulation of COX-2 mRNA and protein levels. This up-regulation was accompanied by a 1.6-fold increase in PGE2 synthesis. Pretreatment of HMEC-1 with a selective COX-2 inhibitor, NS-398, abolished VEGF-induced PGE2 synthesis, suggesting specific up-regulation of COX-2 activity by VEGF in HMEC-1. Transient transfection assays using deletion mutants of the human COX-2 promoter fused to the luciferase reporter gene indicated critical requirement of a regulatory region spanning -828/-123 bp for VEGF induction of COX-2 promoter activity in HMEC-1. Site-directed mutation analysis demonstrated that a GATA cis-acting element at -685/-680 bp was essential for VEGF- induced COX-2 promoter activity in HMEC-1. These observations are of particular importance given the recent demonstrations of critical requirement of COX-2 isoenzyme for tumor growth and angiogenesis.