Cw. Hendrickse et al., ACTIVITIES OF PHOSPHOLIPASE A(2) AND DIACYLGLYCEROL LIPASE ARE INCREASED IN HUMAN COLORECTAL-CANCER, British Journal of Surgery, 82(4), 1995, pp. 475-478
Experimental, clinical and epidemiological studies have implicated ara
chidonic acid and its metabolites as important mediators in colorectal
carcinogenesis. Although arachidonic acid levels are increased in tum
our membrane lipids, its availability for metabolic processes is not k
nown. The activities of phospholipase A(2) (PLA(2)) and diacylglycerol
lipase therefore were assessed in tumour and normal mucosal specimens
from 20 patients with colorectal cancer using C-14-radiolabelled subs
trates. The median (interquartile range) PLA(2) activity was increased
in tumour tissue (10.5 (6.0, 18.5) pmol arachidonic acid mg(-1) h(-1)
) compared with that in normal mucosa (5.6 (2.5, 8.5) pmol arachidonic
acid mg(-1) h(-1)) (P < 0.001, Wilcoxon signed rank test). Activity o
f diacylglycerol lipase was also greater in tumoral tissue (47.4 (21.6
, 82.1) pmol arachidonic acid mg(-1) h(-1)) than in mucosa (19.1 (9.4,
42.9) pmol arachidonic acid mg(-1) h(-1)) (P < 0.005). There was no c
orrelation between either PLA(2) or diacylglycerol lipase activity and
myeloperoxidase activity, suggesting that these increases were not di
rectly attributable to tumour inflammatory cell infiltrate. Augmentati
on of arachidonic acid release in colorectal tumours may have implicat
ions for therapy.