Cyclooxygenase-2 expression and angiogenesis in gastric hyperplastic polyp--association with polyp size.
BACKGROUND
Cyclooxygenase (COX)-2 is the rate-limiting enzyme in prostaglandin synthesis, and plays an important role in tumor enlargement. COX-2 is expressed in human gastric and colorectal tumors, and the expression increases in a tumor size-dependent manner. In the present study, we attempted to examine the COX-2 expression pattern in gastric hyperplastic polyp, a non-tumorous lesion.


METHODS
Fifty-eight gastric hyperplastic polyps, obtained by endoscopic polypectomy, were immunostained with anti-COX-2 and antivascular endothelial growth factor (VEGF) antibodies. Microvessel density (MVD) was determined by von Willebrand factor immunostaining.


RESULTS
In larger gastric hyperplastic polyps, COX-2 was expressed mainly on the luminal side of the polyp stroma, while it was absent in smaller polyps. A significant correlation between COX-2 immunoreactivity and polyp size was observed (p < 0.01). High VEGF expression and MVD were observed mainly in the same stromal region of the polyps where COX-2 was expressed. Both VEGF expression and MVD were also correlated with polyp size significantly (ps < 0.01).


CONCLUSIONS
COX-2 expression increased in a size-dependent manner in non-tumorous hyperplastic polyps, suggesting that COX-2 expression is not necessarily linked to epithelial cell transformation. Moreover, COX-2 may participate in polyp enlargement through angiogenesis by promoting VEGF production.
Department of Gastroenterology and Hepatology, Kyoto University Graduate School of Medicine, Shogoin-Kawara-cho, Kyoto, Japan.
Mayumi
M
Kawada
Hiroshi
H
Seno
Manabu
M
Wada
Katsumasa
K
Suzuki
Naoki
N
Kanda
Takahisa
T
Kayahara
Hirokazu
H
Fukui
Mitsutaka
M
Sawada
Toru
T
Kajiyama
Masahiko
M
Sakai
Tsutomu
T
Chiba
D000368:Aged; D051546:Cyclooxygenase 2; D005260:Female; D005753:Gastric Mucosa / Q000098:blood supply / Q000201:enzymology / Q000473:pathology; D006801:Humans; D006965:Hyperplasia / Q000201:enzymology / Q000473:pathology; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000201:enzymology* / Q000473:pathology; D011127:Polyps / Q000098:blood supply* / Q000201:enzymology* / Q000473:pathology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000098:blood supply* / Q000201:enzymology* / Q000473:pathology
D007527:Isoenzymes; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases