Danazol inhibits aromatase activity of endometriosis-derived stromal cells by a competitive mechanism.

OBJECTIVE: To evaluate the inhibitory effect of danazol on estrogen (E) production in endometriosis. DESIGN: Prospective randomized study. SETTING: Academic research unit of the department of obstetrics and gynecology in a university hospital. PATIENT(S): Thirteen patients with endometriosis. INTERVENTION(S): Danazol was added to the culture of endometriosis-derived stromal cells or suspensions of microsomes prepared from chocolate cysts. MAIN OUTCOME MEASURE(S): The aromatase activities as well as mRNA and protein levels of aromatase in endometriosis-derived stromal cells or microsomes of endometriosis were examined. RESULT(S): Danazol treatment with a concentration greater than 10(-6) M significantly suppressed aromatase activity of endometriosis-derived stromal cells under basal and prostaglandin E(2) (PGE(2))-stimulated conditions. Danazol (10(-5) M) did not affect mRNA and protein levels of aromatase. Danazol competitively inhibited aromatase activity (by 1.7 x 10(-6) M of calculated Ki and 2.9 x 10(-5) M of Ki') of endometriosis microsomes. CONCLUSION(S): Danazol competitively inhibited aromatase activity in endometriosis-derived stromal cells without affecting either the mRNA or protein levels of aromatase. These results indicate the efficacy of local application of danazol to endometriotic lesions.

Aromatase expression in stromal cells of endometrioid endometrial cancer correlates with poor survival.

PURPOSE AND EXPERIMENTAL DESIGN: To assess the prognostic significance of intratumoral aromatase in endometrioid endometrial cancer, sections from 55 patients with endometrial cancer were evaluated for expression of aromatase using immunohistochemistry, and the correlation between aromatase expression and clinicopathologic parameters were analyzed. RESULTS: Immunohistochemical staining for aromatase was positive for 32 (58%), 20 (36%), and 19 (34%) patients in cancer epithelial cells, stromal cells, and myometrial cells around the flank invasion, respectively. In situ hybridization also detected aromatase mRNA in all three types of cells. RT-PCR analysis revealed that aromatase mRNA was 2.5 +/- 1.0 amol/mug total RNA (mean +/- SE; n = 7) in tumor tissue. Western blot analysis detected the expected aromatase protein size of 58 kDa in cancer tissues more abundantly than in cancer-free endometrium (n = 3). The immunoreactivity in stromal cells correlated positively with advanced surgical stage and poor survival. Survival analysis revealed that the immunoreactivity of stromal cells was a significant prognostic factor, independent of histologic grade, muscular invasion, and lymph node metastasis, but dependent on surgical stage. By contrast, the immunoreactivity of aromatase both in cancer epithelial cells and myometrial cells did not correlate with prognosis. CONCLUSIONS: To the best of our knowledge, this is the first evidence associating intratumoral aromatase expression in stromal cells and poor survival in endometrioid endometrial cancer. This positive linkage indicates that local expression of aromatase plays a role in tumor progression through the formation of in situ estrogens. In situ expression of aromatase may offer a potential target for management of endometrial cancers.

Increased expression of type I 17beta-hydroxysteroid dehydrogenase enhances in situ production of estradiol in uterine leiomyoma.

Expression of 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) was compared between leiomyoma and myometrium. Cytosolic fractions from leiomyoma homogenate displayed 5-fold higher activity (estrone to estradiol), compared with surrounding myometrium (n = 6, P < 0.05), whereas microsomal fractions showed no difference. Oxidative activity (estradiol to estrone) did not differ between leiomyoma and myometrium. Levels of mRNA for 17beta-HSDs were then measured using real-time PCR techniques. Among the eight different types of 17beta-HSDs (types 1-5, 7, 8, and 10), type 1 was the only enzyme displaying differential expression between leiomyoma and myometrium. Mean concentration of type 1 17beta-HSD mRNA was 4-fold higher in leiomyoma than in surrounding myometrium (n = 20, P < 0.05). Type 1 transcript levels correlated significantly with reductive activity in individual samples (n = 6, P < 0.05). Northern blot analysis of leiomyoma and myometrium tissues detected 2.3- and 1.0-kb transcripts of type 1 enzyme, whereas the major 1.3-kb transcript for 17beta-HSD in placenta-derived JEG-3 cells was not detected. None of the factors increasing mRNA levels for type 1 enzyme in placenta increased mRNA levels in leiomyoma. These results indicate that leiomyoma tissues overexpress type 1 17beta-HSD, resulting in high conversion of estrone to estradiol. In situ expression of type 1 17beta-HSD may play a role in self-supported growth of leiomyoma cells.

Decreased expression of early growth response-1 and its role in uterine leiomyoma growth.

Expression of early growth response (Egr)-1, a transcriptional factor implicated in growth regulation, is suppressed in several malignant tumors. The present study investigated the expression of Egr-1 and related genes in uterine leiomyoma and normal myometrium to determine possible contributions of Egr-1 to neoplastic growth in leiomyoma cells. Levels of Egr-1 transcripts were decreased in all leiomyomas (n = 20) to approximately 10% of levels in corresponding myometrium, where basal expression was high. Preoperative leuprorelin acetate therapy increased levels of Egr-1 mRNA in normal myometrium only. Northern blot analysis using additional sample sets (n = 5) revealed the full-length Egr-1 transcript. Western blot analysis (n = 5) confirmed decreased expression of Egr-1 protein. Southern blot analysis of the Egr-1 gene and microsatellite analysis of the chromosomal location at 5q31 (D5S414, D5S500, and D5S476) revealed neither DNA recombination nor loss of heterozygosity in leiomyomas. Moreover, Egr-1 retained identical responsiveness to phorbol 12-myristate 13-acetate in primary cultures derived from both leiomyoma and normal tissues. Electrophoretic mobility shift analysis revealed that phorbol 12-myristate 13-acetate-induced Egr-1 in leiomyoma cells retained DNA binding ability. Egr-1 thus appears functionally intact in leiomyoma cells. Finally, consistent with the role of Egr-1 in growth inhibition, transfection of Egr-1 expression vector into a myometrial cell line (KW) that expresses low levels of Egr-1 and displays rapid growth inhibited thymidine uptake in these cells. Egr-1 may display tumor-suppressing activity and offers a potential target for leiomyoma management.