NSAIDs inhibit the activation of egr-1 gene in microvascular endothelial cells. A key to inhibition of angiogenesis?

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, indomethacin (IND), ibuprofen and newer cyclooxygenase-2 selective NSAIDs (e.g. celecox ib) delay gastric ulcer healing partly through the inhibition of angiogenes is, but the molecular mechanisms involved are not fully elucidated. Effecti ve angiogenesis is required for ulcer healing to supply oxygen and nutrient s to the healing site. The early growth response factor (Egr-1) is a transc ription factor, which is rapidly activated by a variety of extracellular si gnals or tissue injury and is important for angiogenesis to occur. This stu dy aimed to determine whether indomethacin (IND) and/or the selective COX-2 inhibitor, NS-398, interfere with egr-1 gene expression in human microvasc ular endothelial cells (HMVEC) in response to vascular endothelial growth f actor (VEGF) stimulation. HMVEC were treated with 0.5 mM IND or 100 muM NS- 398 for 16 h, and then VEGF (10 ng/ml) or vehicle was added. Egr-1 mRNA and protein expression levels were determined by RT-PCR and Western-blotting, respectively. VEGF treatment caused a significant elevation of Egr-1 mRNA ( 261 +/- 21%, P < 0.001) and protein expression (174 +/- 15%, P < 0.01) vs. vehicle. IND pre-treatment significantly inhibited VEGF-induced Egr-1 mRNA expression by 29 +/- 4% (P < 0.01) and protein expression by 41 +/- 8% (P < 0.05). NS-398 inhibited VEGF-induced Egr-1 mRNA and protein expression by 23 +/- 3% and 35 +/- 4%, respectively (both P < 0.01). Since trancriptional activation of egr-1 is responsible for expression of proteins involved in proliferation of endothelial cells essential for angiogenesis, these result s provide a new mechanism for NSAIDs' interference with angiogenesis. Publi shed by Elsevier Science Ltd.