Cytosolic phospholipase A2, cyclo-oxygenases and arachidonate in human stomach tumours.
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.
Soydan
A S
AS
Academic Department of Surgery, Rayne Institute, King's College School of Medicine and Dentistry, London, U.K.
Gaffen
J D
JD
Weech
P K
PK
Tremblay
N M
NM
Kargman
S
S
O'Neill
G
G
Bennett
A
A
Tavares
I A
IA
D000368:Aged; D000369:Aged, 80 and over; D016718:Arachidonic Acid / Q000032:analysis*; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D005753:Gastric Mucosa / Q000737:chemistry / Q000201:enzymology; D006801:Humans; D015151:Immunoblotting; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*; D013274:Stomach Neoplasms / Q000737:chemistry / Q000201:enzymology*
D016718:Arachidonic Acid; D011451:Prostaglandin-Endoperoxide Synthases; D010741:Phospholipases A; D054467:Phospholipases A2