COX-2 expression in sporadic colorectal adenomatous polyps is linked to adenoma characteristics.
OBJECTIVE
To assess cyclooxygenase-2 (COX-2) expression in sporadic colonic adenomas and to explore the association of COX-2 positivity with adenoma characteristics linked to increased risk of malignant transformation.


RESULTS
COX-2 expression and localization were assessed in 64 colorectal adenomas and 35 paired adjacent normal colonic mucosal biopsy specimens. The number of adenoma specimens was then extended to include polyps exhibiting an increasing degree of epithelial dysplasia. Forty colonic hyperplastic polyps were also identified from the pathology diagnostic database and included in the analysis. Immunohistochemistry was performed with the Envision+ peroxidase-linked biotin-free system incorporating a signal amplification step. There was a statistically significant increase in COX-2 expression in colonic polyps compared with paired adjacent normal mucosa, chi(2) = 40.1, P = 0.001. The probability of COX-2 expression increased along with increasing adenoma size and increasing degree of epithelial dysplasia. Fifty-five per cent of the hyperplastic polyp specimens expressed COX-2.


CONCLUSIONS
This study associates COX-2 epithelial expression with a number of adenoma characteristics that convey an increased risk of malignant transformation. This is in keeping with a positive role for COX-2 in early colorectal carcinogenesis.
McLean
M H
MH
GI Research Group, Department of Medicine & Therapeutics, University of Aberdeen, Aberdeen, UK.
Murray
G I
GI
Fyfe
N
N
Hold
G L
GL
Mowat
N A G
NA
El-Omar
E M
EM
D018256:Adenomatous Polyps / Q000737:chemistry / Q000201:enzymology*; D014408:Biomarkers, Tumor / Q000032:analysis; D002471:Cell Transformation, Neoplastic; D003111:Colonic Polyps / Q000737:chemistry / Q000201:enzymology*; D015179:Colorectal Neoplasms / Q000737:chemistry / Q000201:enzymology*; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004847:Epithelial Cells / Q000737:chemistry / Q000201:enzymology; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007124:Immunoenzyme Techniques; D007413:Intestinal Mucosa / Q000737:chemistry / Q000201:enzymology*; D011230:Precancerous Conditions / Q000737:chemistry / Q000201:enzymology; D046888:Tissue Array Analysis
D014408:Biomarkers, Tumor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human