Expression of cyclooxygenase-2, matrix metalloproteinase-2 and matrix metalloproteinase-9 in premenopausal and postmenopausal endometrial polyps.

Objectives: Cyclooxygenase-2 (COX-2) and matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9) are influenced by relative levels of estrogen and are involved in promoting cell proliferation and angiogenesis. The present study investigated expression of COX-2, MMP-2 and MMP-9 in endometrial polyps from premenopausal and postmenopausal women.

Methods: Premenopausal (n=18) and postmenopausal (n=22) endometrial polyps were included in the study. None of the women were using non-steroid anti-inflammatory drugs, hormone replacement therapy or any other estrogen containing pills. Immunohistochemical analysis for MMP-2, MMP-9 and COX-2 were performed on formalin fixed, paraffin-embedded tissue using the streptavidin-biotin-peroxidase technique. The cut-off value for positiviy was set to 10% and staining more than 50% was regarded as intense staining. Staining of 10-25% and 25-50% were recorded as mild and moderate, respectively.

Results: COX-2, MMP-2 and MMP-9 were stained in epithelial cells and stroma of premenopausal and postmenopausal endometrial polyps. Stromal expression of COX-2, MMP-2 and MMP-9 were found significantly higher in premenopausal polyps compared to postmenopausal polyps (p<0.05). There were no other significant differences in the immunohistochemical expressions in the epithelium of premenopausal and postmenopausal endometrial polyps except MMP-9.

Conclusion: Polyps from both premenopausal and postmenopausal women express epithelial and stromal COX-2, MMP-2 and MMP-9, however immunohistochemical expression of these markers may be different due to menopausal status. This may suggest a shared pathogenesis for pre- and postmenopausal endometrial polyps.