Soydan A S, Gaffen J D, Weech P K, Tremblay N M, Kargman S, O'Neill G, Bennett A, Tavares I A
Academic Department of Surgery, Rayne Institute, King's College School of Medicine and Dentistry, London, U.K.
Eur J Cancer. 1997 Aug;33(9):1508-12. doi: 10.1016/s0959-8049(97)00168-8.
Human stomach tumours usually form more prostaglandins (PGs) than their associated normal mucosa/submucosa, but the mechanisms are not fully understood. The key enzymes are cytosolic phospholipase A2 (cPLA2, Mr 85,000) and the cyclo-oxygenases (COXs) which exist in constitutive (COX-1) and inducible forms (COX-2). In human stomach tumours and associated macroscopically normal tissues, we determined the fatty acid composition by gas chromatography, amounts of cPLA2, COX-1 and COX-2 by immunoblotting with specific antibodies and cPLA2 enzyme activity using a tritiated substrate. Although compared to normal mucosa there was less arachidonate in tumours (P < 0.05), the arachidonate/total fatty acid ratio was higher. Mean amounts of cPLA2 and COX-1 and cPLA2 activity were similar in tumours and normal mucosa. However, substantial amounts of COX-2 were found in the tumours but not in the mucosa, which may explain why many gastric tumours form increased amounts of PGs.
