Heterogeneity in endometrial expression of aromatase in polyp-bearing uteri.

Background: Comparative assessment of expression of aromatase (CYP19A1) messenger RNA (mRNA) in pathological and non-pathological sites within the uterine cavity of mid reproductive age women diagnosed with endometrial polyp (EP).

Methods: We report a case series of seven premenopausal infertile women undergoing hyseroscopic removal of EP. Directed endometrial biopsies were collected from the EP (P), from the endometrium immediately adjoining the EP (A) and from a normal appearing site remote from the EP (R). Expression of CYP191A1 mRNA within the respective samples in each patient was evaluated by quantitative real-time PCR. Fold changes in the mRNA expression of CYP191A1 within the P versus the R and A endometrial sites were calculated to assess the hypothesis of a 'field effect' in the expression of aromatase within EP bearing endometria.

Results: Overall, similar mRNA expression of CYP191A1 gene was demonstrated between P and A endometrial samples. In only one of the seven patients, aromatase expression within P was enhanced by almost 4-fold compared with R (P = 0.14 for comparison with the difference in CYP19A1 expression in P versus R in the remainder of the patients). In contrast, in three of the seven patients, P demonstrated a marked (>1000-fold) under-expression in CYP191A1 mRNA levels compared with the R endometrium (P = 0.22).

Conclusions: We herein provide evidence of heterogeneity in the expression of endometrial aromatase in premenopausal uteri bearing EPs. Our data suggest that an overexpression of endometrial aromatase may underlie pathogenesis of EP at least in a subset of cases.