Aromatase activity in monolayer cell cultures of human endometrium

SULFATION PATHWAYS: Contribution of intracrine oestrogens to the aetiology of endometriosis

Endometriosis is an incurable hormone-dependent inflammatory disease that causes chronic pelvic pain and infertility characterized by implantation and growth of endometrial tissue outside the uterine cavity. Symptoms have a major impact on the quality of life of patients resulting in socioeconomic, physical and psychological burdens. Although the immune system and environmental factors may play a role in the aetiology of endometriosis, oestrogen dependency is still considered a hallmark of the disorder. The impact of oestrogens such as oestrone and particularly, oestradiol, on the endometrium or endometriotic lesions may be mediated by steroids originating from ovarian steroidogenesis or local intra-tissue production (intracrinology) dependent upon the expression and activity of enzymes that regulate oestrogen biosynthesis and metabolism. Two key pathways have been implicated: while there is contradictory data on the participation of the aromatase enzyme (encoded by CYP19A1), there is increasing evidence that the steroid sulphatase pathway plays a role in both the aetiology and pathology of endometriosis. In this review, we consider the evidence related to the pathways leading to oestrogen accumulation in endometriotic lesions and how this might inform the development of new therapeutic strategies to treat endometriosis without causing the undesirable side effects of current regimes that suppress ovarian hormone production.

Detection of testosterone and estrogen receptors in the postmenopausal endometrium

OBJECTIVE

To detect the presence of testosterone and estrogen receptors in the stroma and glandular epithelium in the malignant and non-malignant endometrium.

METHODS

One hundred and forty-five consecutively-enrolled peri- or postmenopausal patients were submitted to diagnostic or operative hysteroscopy. These patients either had a history of abnormal uterine bleeding or they were asymptomatic with an endometrial echo greater than 4 mm. The presence of estrogen and testosterone receptors was determined in endometrial samples by immunohistochemistry, using monoclonal antibodies and a streptavidin-biotin peroxidase complex system with diamino benzidine as the chromogen.

RESULTS

Testosterone receptors were detected mainly in the stroma in the non-malignant endometrial lesions and in the atypical glandular epithelium in cases of estrogen-positive endometrial carcinomas.

CONCLUSIONS

The presence of testosterone receptors in estrogen receptor positive endometrial carcinomas may be involved in the mechanism of cell proliferation in these tumors. The strong staining reaction for testosterone receptors in the endometrial glands can be considered one of the features of invasive malignancy.

Detection of aromatase cytochrome P-450 in endometrial biopsy specimens as a diagnostic test for endometriosis

OBJECTIVE

To evaluate the clinical usefulness of examining endometrial biopsy specimens for aromatase cytochrome P-450 as a diagnostic test for endometriosis.

DESIGN

Retrospective, case-controlled study.

SETTING

Department of Obstetrics and Gynecology, Kyoto Prefectural University of Medicine, Kyoto, Japan.

PATIENT(S)

One hundred five women of reproductive age with normal menstrual cycles underwent endometrial biopsy laparotomy or laparoscopy, and examination of their tissue revealed endometriosis, adenomyosis, and/or leiomyomas. Patients who had cervical carcinoma in situ but no other gynecologic disease were considered to be disease-free.

INTERVENTION(S)

Endometrial biopsy specimens were collected.

MAIN OUTCOME MEASURE(S)

The expression of aromatase cytochrome P-450 was examined by reverse transcription-polymerase chain reaction and immunohistochemical analysis. The distribution and intensity of the immunostaining was assessed using a semiquantitative index designed H-score.

RESULT(S)

Immunostaining for aromatase cytochrome P-450 was detected in biopsy specimens obtained from patients with endometriosis, adenomyosis, and/or leiomyomas but not in specimens obtained from disease-free patients (H-score <20), with a sensitivity and specificity of 91% and 100%, respectively.

CONCLUSION(S)

The expression of aromatase cytochrome P-450 in biopsy specimens of eutopic endometrium distinguishes between disease-free women and women with endometriosis, adenomyosis, and/or leiomyomas. This technique can be used at outpatient infertility clinics as an initial screening procedure to rule out the presence of estrogen-dependent disease.

Estrogen productivity of endometrium and endometrial cancer tissue; influence of aromatase on proliferation of endometrial cancer cells

Aromatase, estrone (E1) sulfatase and E1 sulfotransferase activities were examined in endometrium and endometrial cancer tissue preparations. Aromatase and E1 sulfatase activities in endometrial cancer tissues were found to be significantly higher than in normal endometrial tissues. However, E1 sulfotransferase activity did not differ between benign and malignant tissue. We also examined the effect of testosterone (T) on aromatase activity and tritiated thymidine uptake (DNA synthesis) in various cultured cervical or corpus endometrial cancer cell lines (OMC-4, HHUA, Ishikawa, HEC-59). The results demonstrated that only the HEC-59 cell line had high aromatase activity and increased its DNA synthesis in response to T. This increase of DNA synthesis by T was not suppressed by simultaneous addition of cyproterone acetate, but was by tamoxifen. These data suggest that in situ estrogen production in endometrial cancer tissue is biologically important and that aromatase in cancer cells may contribute partially to cell proliferation if androgen substrate is provided.