Expression of cyclooxygenase 1 and 2 by human gastric endothelial cells

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Abstract
BACKGROUND Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) and cause gastric ulceration. NSAIDs also impair granulation tissue angiogenesis and healing of established gastric ulcers in humans. The mechanism whereby NSAIDs inhibit granulation tissue angiogenesis is unknown but may involve inhibition of either or both COX isoforms (COX-1 and COX-2). AIMS To investigate COX expression by human gastric endothelial (HuGE) cells during angiogenesis in vitro. METHODS COX-1 and COX-2 expression by HuGE cells was investigated by western blot analysis, indirect immunofluorescence, reverse transcriptase polymerase chain reaction, and measurement of prostaglandin E2 synthesis. Plating onto basement membrane matrix and stimulation by phorbol ester were used as in vitro models of angiogenesis. RESULTS Under normal culture conditions (30% serum), HuGE cells expressed COX-1 and low levels of COX-2. COX-2 expression was induced in HuGE cells in both angiogenesis models. Prostaglandin E2 production and tubular structure formation by HuGE cells on basement membrane matrix was significantly inhibited by a selective COX-2 inhibitor (NS-398). CONCLUSION Angiogenesis by HuGE cells in vitro was associated with induction of functional COX-2 expression. A selective COX-2 inhibitor significantly decreased HuGE cell angiogenesis on basement membrane matrix. Extrapolation of these data to human gastric ulcer angiogenesis in vivo suggests that selective COX-2 inhibitors could delay gastric ulcer healing to the same extent as traditional NSAIDs which are non-selective COX inhibitors.