RU486 suppresses prolactin production in explant cultures of leiomyoma and myometrium.

OBJECTIVE

To assess the action of RU486 (mifepristone), in the presence and absence of P, on PRL production by explant cultures of leiomyoma and myometrium.

DESIGN

Explant cultures using tissue from nine premenopausal women undergoing hysterectomy in the proliferative phase of the menstrual cycle; immunohistochemical staining of tissue sections from five patients for P receptor (PR) subtype.

MAIN OUTCOME MEASURES: Prolactin secretion (measured by RIA), lactate dehydrogenase secretion (measured by quantitative colorimetric assay), and immunohistochemistry for PR subtype.

RESULTS

Prolactin secretion was decreased in leiomyomas by RU486 at concentrations of 10(-7) M and 10(-5)M when normal serum-containing medium was used. In experiments with all detectable P removed from serum, PRL secretion was suppressed in both leiomyomas and myometrium at an RU486 concentration of 10(-7)M. Immunohistochemistry results suggest that the A form of the PR is the dominant form in both leiomyomas and myometrium.

CONCLUSIONS

Prolactin production is suppressed in both leiomyomas and myometrium after treatment with RU486 in vitro, and this suppression may serve as a marker for the clinical effectiveness of agents used in the treatment of leiomyomas.