Is there a place for practical chemoprevention of colorectal cancer in light of COX-2 heterogeneity?

Abstract

COX-2 overexpression is widely recognized as an accidental and relatively important factor in the progress of colon neoplasia, but the practical significance of it has not yet been defined. As such, the purposes of the study were: an analysis of the changes of COX-2 expression within colon adenomas in the dependence of progress of dysplastic level within colon adenomas, the analysis of COX-2 expression in cryptal and superficial parts of polyp and, additionally, the analysis of the COX-2 heterogeneity between colon adenomas. One hundred and four cases with completely resected adenomas with high-grade epithelial dysplasia were included in the research. Each polyp had persistent lowgrade dysplasia and normal colon mucosa at the base as an internal control. Immunohistochemical analysis with monoclonal COX-2 antibody was performed. Regression of COX-2 expression in high-grade colon intraepithelial lesions (HGCoIN) compared with low-grade colon intraepithelial lesions (LGCoIN) (p = 0.00001) was observed. No correlation between stromal COX-2 expression and either LGCoIN or HGCoIN was found (p >0.05). The next important observation was a difference in superficial and cryptal COX-2 expression (p < 0.001) and the evident heterogeneity of COX-2 expression among adenomas at LGCoIN as well HGCoIN foci (p < 0.01). The regression of COX-2 expression in high-grade parts of adenomas which we described may result in a reduction of the role of chemoprevention by the use of NSAIDs.