Reprod. Nutr. Dev. 45 (2005) 709-720
DOI: 10.1051/rnd:2005055

The effects of dietary phytoestrogens on aromatase activity in human endometrial stromal cells

Katie M. Edmunds^a, Alison C. Holloway^a, Denis J. Crankshaw^a, Sanjay K. Agarwal^b and Warren G. Foster<sup>a

a</sup>  Reproductive Biology Division, Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, USA
^b  Department of Reproductive Medicine, University of California, San Diego, California, USA

(Received 14 January 2005; accepted 26 May 2005)

Abstract - Dietary phytoestrogens have been reported to inhibit aromatase activity in placental microsomes, but the effects in the human endometrium are unknown. Aromatase, the rate-limiting enzyme in the conversion of androgens to estrogens, has recently been shown to be expressed in the endometrium of women with endometriosis and is thought to play a role in the pathophysiology of this disease. Therefore, the objective of this study was to screen dietary phytoestrogens for their ability to inhibit aromatase activity in human endometrial stromal cells (ESC) and identify potential novel therapeutic agents for the treatment of endometriosis. The inhibition of aromatase activity by direct interaction with the dietary phytoestrogens genistein, daidzein, chrysin, and naringenin was tested in a cell free assay. Furthermore, test compound effects on aromatase activity in ESC cultures were also examined. Genistein and daidzein were inactive in the human recombinant aromatase assay whereas naringenin and chrysin inhibited aromatase activity. However, genistein (1 nM to 1 mM) stimulated aromatase activity in ESC whereas other phytoestrogens had no effect. Immunopositive aromatase cells were demonstrated in genistein-treated ESC but not in untreated control cultures. Taken together, our data suggest that genistein can increase aromatase activity in ESC likely via increased enzyme expression.

Key words: phytoestrogens / endometriosis / aromatase / genistein / endometrium

Corresponding author: Warren G. Foster fosterw@mcmaster.ca

© INRA, EDP Sciences 2005