Oestrogen deficiency causes DNA damage in uterine leiomyoma cells: a possible mechanism for shrinkage of fibroids by GnRH agonists

Objective To examine whether gonadotrophin-releasing hormone agonist or oes tradiol can directly affect DNA in leiomyoma cells. Design In vitro explant culture of leiomyoma cells. Setting University research group. Sample Leiomyoma cells were cultured from the specimens of four premenopaus al women at myomectomy. Methods The presence of gonadotrophin-releasing hormone receptor in leiomyo ma cells was determined by reverse transcriptase-olymerase chain reaction. Leiomyoma cells were treated with gonadotrophin-releasing hormone agonist o r cultured in different concentrations of oestrogen, progesterone or fetal calf serum for one, four or seven days. Main outcome measures Cell number, expression of proliferating cell nuclear antigen, and DNA damage after one, four or seven days of treatment. Results Gonadotrophin-releasing hormone receptor messenger ribonucleic acid was detected on cultured leiomyoma cells. Leiomyoma cell growth was not af fected by the addition of gonadotrophin-releasing hormone agonist or proges terone, but increased with oestrogen or fetal calf serum supplementation. O verexpression of proliferating cell nuclear antigen was prevented in cultur es added with oestrogen or fetal calf serum, but not related to gonadotroph in-releasing hormone agonist treatment. Significant decreases in DNA damage as indicated by decreased comet number were found in the leiomyoma culture s treated with oestrogen or fetal calf serum for four and seven days but no t with gonadotrophin-releasing hormone agonist or progesterone. Furthermore , 5% fetal calf serum supplementation was more growth supporting and more s ignificantly reduced the comet number than 250 pM 17 beta -oestradiol. Conclusion Cell growth, proliferating cell nuclear antigen expression and D NA damage are dependent on oestrogen or fetal calf serum, but independent o f gonadotrophin-releasing hormone agonist or progesterone. Our findings sug gest that gonadotrophin-releasing hormone agonist-induced leiomyoma shrinka ge may be due in part to a mechanism involving DNA damage, and support th e hypothesis that gonadotrophin-releasing hormone agonist exerts its action indirectly through oestrogen action on the rumour level.