Cyclooxygenase-2 activation mediates the proangiogenic effect of nitric oxide in colorectal cancer.
OBJECTIVE
Up-regulation of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) enzymes has been reported in colorectal cancer. We aimed at evaluating the possible interaction between the nitric oxide and COX-2 pathways, and its effect on promoting tumor angiogenesis.


METHODS
Expression of iNOS, COX-2, vascular endothelial growth factor (VEGF), and CD31 was analyzed in tumor samples and corresponding normal mucosa obtained from 46 surgical specimens. We also evaluated iNOS activity, prostaglandin E(2) (PGE(2)), cyclic GMP and cyclic AMP production in the same specimens. Nitrite/nitrate levels, and PGE(2) and VEGF production were assessed in HCT116 and HT29 colon cancer cell lines after induction and selective inhibition of the two enzyme pathways.


RESULTS
A significant correlation was found between iNOS and COX-2 immunohistochemical expression. PGE(2) production significantly correlated with iNOS activity and cGMP levels. A significant correlation was also found among PGE(2) production, microvessel density, and VEGF expression. Coinduction of both iNOS and COX-2 activities occurred after lipopolysaccharide (LPS) and epidermal growth factor (EGF) treatment in HCT116 and HT29 cells. Inhibition of iNOS by 1400W significantly reduced both LPS- and EGF-induced PGE(2) production. Treatment with LPS, EGF, and arachidonic acid significantly increased VEGF production in the iNOS-negative/COX-2-positive HT29 cells. This effect was completely reversed by treatment with the selective COX-2 inhibitor celecoxib.


CONCLUSIONS
Our data showed a prominent role of nitric oxide in stimulating COX-2 activity in colorectal cancer. This interaction is likely to produce a cooperative effect in promoting angiogenesis through PGE(2)-mediated increase in VEGF production.
Cianchi
Fabio
F
Department of General Surgery, Medical School, University of Florence, Florence, Italy. cianchif@mail.unifi.it
Cortesini
Camillo
C
Fantappiè
Ornella
O
Messerini
Luca
L
Sardi
Iacopo
I
Lasagna
Nadia
N
Perna
Federico
F
Fabbroni
Valentina
V
Di Felice
Annamaria
A
Perigli
Giuliano
G
Mazzanti
Roberto
R
Masini
Emanuela
E
D000368:Aged; D000369:Aged, 80 and over; D000578:Amidines / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism; D001596:Benzylamines / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D002455:Cell Division; D045744:Cell Line, Tumor; D002470:Cell Survival; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D008833:Microcirculation; D008875:Middle Aged; D008954:Models, Biological; D009389:Neovascularization, Pathologic; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D016896:Treatment Outcome; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D000578:Amidines; D001596:Benzylamines; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; C104820:N-(3-(aminomethyl)benzyl)acetamidine; D009566:Nitrates; D009573:Nitrites; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; D016718:Arachidonic Acid; D009569:Nitric Oxide; D000242:Cyclic AMP; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D006152:Cyclic GMP; D015232:Dinoprostone