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T M Penning

Introduction Mammalian 17β-hydroxysteroid dehydrogenases (17β-HSDs) catalyze the final steps in male and female sex hormone biosynthesis. In the Leydig cells in the testis, 17β-HSD converts androst-4-ene-3,17-dione into the male sex hormone testosterone. In the ovary and placenta, 17β-HSD converts estrone (a weak estrogen) into 17β-estradiol (a potent estrogen) (Fig. 1). Deficiencies in testicular 17β-HSD have been associated with pseudohermaphroditism (Gross et al. 1986, Wilson et al. 1987, 1988, Farkas & Rosler 1993, Geissler et al. 1994), implicating the importance of this enzyme in testosterone production. It follows that inhibition of this enzyme could block androgen biosynthesis and androgen action. On this basis, selective inhibitors of testicular 17β-HSD have the potential to prevent the growth of androgen-dependent tumors, e.g. benign hyperplasia and cancer of the prostate. Moreover, effective inhibitors could be used as adjuvants to enhance the efficacy of androgen receptor antagonists. In human breast tissue, 17β-HSD is responsible
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M C Pike, J R Daniels, and D V Spicer

Abstract

Epidemiological studies have consistently found that bilateral oophorectomy at a young age substantially reduces breast cancer risk. Such surgical menopause around age 35 has been found to reduce risk by 60 to 75%. A reversible medical oophorectomy using an agent such as a gonadotropin-releasing hormone agonist (GnRHA) should achieve a similar reduction in risk. Although the use of GnRHA alone is unacceptable because of the associated hypoestrogenic side-effects, these can be satisfactorily prevented by add-back low-dose estrogen treatment with intermittent progestin to protect the endometrium. It is estimated that a regimen of GnRHA plus add-back ultra low-dose estrogen and progestin would prevent some two-thirds of current breast cancer if used from age 30. If used from age 20 almost nine out of ten current breast cancer cases would be avoided. If, as is likely, these estimates also apply to women at high genetic risk of breast cancer because of possession of a BRCA1 or BRCA2 gene, their breast cancer risk would be reduced to below that of 'normal' women. The protective effects on ovarian cancer are calculated to be greater than the protective effects on breast cancer. Practical chemoprevention of breast and ovarian cancer using this approach should be possible within 5 years.

Endocrine-Related Cancer (1997) 4 125-133

Open access

Evangelia-Ourania Fourkala, Alexey Zaikin, Matthew Burnell, Aleksandra Gentry-Maharaj, Jeremy Ford, Richard Gunu, Christina Soromani, Guido Hasenbrink, Ian Jacobs, Anne Dawnay, Martin Widschwendter, Hella Lichtenberg-Fraté, and Usha Menon

Postmenopausal women with elevated serum sex steroids have an increased risk of breast cancer. Most of this risk is believed to be exerted through binding of the sex steroids to their receptors. For the first time, we investigate the association of estrogen receptor (ER) and androgen receptor (AR) serum bioactivity (SB) in addition to hormone levels in samples from women with breast cancer collected before diagnosis. Two hundred postmenopausal women participating in the UK Collaborative Trial of Ovarian Cancer Screening who developed ER-positive breast cancer 0.6–5 years after sample donation were identified and matched to 400 controls. ER and AR bioassays were used to measure ERα, ERβ, and AR SB. Androgen and estrogen levels were measured with immunoassays. Subjects were classified according to quintiles of the respective marker among controls and the associations between SB and hormones with breast cancer risk were determined by logistic regression analysis. ERα and ERβ SB were significantly higher before diagnosis compared with controls, while estrogens showed no difference. Women had a twofold increased breast cancer risk if ERα SB (odds ratio (OR), 2.114; 95% confidence interval (CI), 1.050–4.425; P=0.040) was in the top quintile >2 years before diagnosis or estrone (OR, 2.205; 95% CI, 1.104–4.586; P=0.029) was in the top quintile <2 years before diagnosis. AR showed no significant association with breast cancer while androstenedione (OR, 3.187; 95% CI, 1.738–6.044; P=0.0003) and testosterone (OR, 2.145; 95% CI, 1.256–3.712; P=0.006) were significantly higher compared with controls and showed a strong association with an almost threefold increased breast cancer risk independent of time to diagnosis. This study provides further evidence on the association of androgens and estrogens with breast cancer. In addition, it reports that high ER but not AR SB is associated with increased breast risk >2 years before diagnosis.

Free access

G Scambia, G Ferrandina, G D'Agostino, A Fagotti, M Di Stefano, F Fanfani, F G Serri, and S Mancuso

Ovarian cancer accounts for 5% of all cancer deaths in Western countries and is the most frequent cause of gynaecologic cancer mortality. The incidence varies with age between 1% and 14% with a peak rate in the eighth decade, and in the majority of cases, the disease has already spread beyond the pelvic cavity at time of diagnosis. Although in the last decades the introduction of cisplatin-based chemotherapy resulted in an improvement of patient survival, the percentage of recurrent disease is high even in those patients who achieve a complete response to chemotherapy, so that more than 80% of patients with advanced stage of disease die within 5 years (Copeland & Gershenson 1986). At present the prognostic characterisation of ovarian cancer patients, based on clinico-pathological parameters, such as stage, histology, grade and residual tumour after surgery, seems to be inadequate, since patients with similar clinico- pathological characteristics often experienced different clinical outcome. Therefore, the identification of biological factors related to tumour aggressiveness could be relevant in order to identify patients with different prognosis and chance to respond to chemotherapy, thus allowing the selection, at time of initial diagnosis, of high risk patients needing more aggressive therapy or alternative treatment, and a closer follow-up. Among the biological parameters proposed as possible prognostic factors in ovarian cancer much attention has been focused on endocrine factors and especially on steroid hormones and their receptors. Although several epidemiological and in vitro evidences have demonstrated that, similarly to breast and endometrial cancer, ovarian cancer cell biology could be influenced by the biochemical pathways promoted by the interaction of estrogens and progesterone with their specific receptors (ER, PR) conflicting data have been reported about the possible clinical role of ER and PR in this neoplasm. This review is aimed: a) to summarise the informations about the influence of steroid hormones and their receptors in the biology of ovarian cancer in in vitro models as well as in primary tumours;b) to investigate the association of steroid hormone receptor expression with the clinico-pathological parameters and the clinical outcome in ovarian cancer patients.c) to report the data of the literature about the rationale and the results of endocrine therapy in ovarian cancer.

Free access

Marc T Goodman, Galina Lurie, Pamela J Thompson, Katharine E McDuffie, and Michael E Carney

Although the role of estrogen in the etiology of ovarian cancer is uncertain, there is increasing evidence that hormone replacement therapy is a risk factor for ovarian malignancy. The production of estrogen involves the conversion of androgens via P450 aromatase, encoded by the CYP19A1 gene. Genetic variation in two CYP19A1 single-nucleotide polymorphisms (SNPs), rs749292 and rs727479, has been found to produce 10–20% increases in estrogen levels among postmenopausal women. We tested the hypothesis that these SNPs were associated with the risk of ovarian cancer in a population-based case–control study in Hawaii, including 367 histologically confirmed epithelial ovarian cancer cases and 602 age- and ethnicity-matched controls. The A allele of rs749292 was positively associated with ovarian cancer risk in a codominant model for all races combined (AG versus AA genotype: odds ratio (OR), 1.48 and 95% confidence interval (CI, 1.07–2.04); GG versus AA: OR, 1.87 (CI, 1.24–2.82); P trend=0.002). Similar significant associations of the rs749292 A allele on the risk of ovarian cancer were found among Caucasian and Japanese women. No relation of the rs727479 SNP to ovarian cancer risk was observed overall, although Caucasian women carrying the variant A allele compared with women with an CC genotype had an OR of 2.91 (CI, 1.15–7.37). These data suggest CYP19A1 variants may influence susceptibility to ovarian cancer.

Free access

Jaesung (Peter) Choi, Reena Desai, Yu Zheng, Mu Yao, Qihan Dong, Geoff Watson, David J Handelsman, and Ulla Simanainen

Haploinsufficient inactivating phosphatase and tensin homolog (Pten) mutations cause Cowden syndrome, an autosomal dominant risk genotype for hormone dependent reproductive cancers. As androgen actions mediated via the androgen receptor (AR) supports uterine growth and may modify uterine cancer risk, we hypothesized that a functional AR may increase PTEN inactivation induced uterine cancer. To test the hypothesis, we compared the PTEN knockout (PTENKO) induced uterine pathology in heterozygous PTENKO and combined heterozygous PTEN and complete AR knockout (PTENARKO) female mice. PTENKO induced uterine pathology was significantly reduced by AR inactivation with severe macroscopic uterine pathology present in 21% of PTENARKO vs 46% of PTENKO at a median age of 45 weeks. This could be due to reduced stroma ERα expression in PTENARKO compared to PTENKO uterus, while AR inactivation did not modify PTEN or P-AKT levels. Unexpectedly, while progesterone (P4) is assumed protective in uterine cancers, serum P4 was significantly higher in PTENKO females compared to WT, ARKO, and PTENARKO females consistent with more corpora lutea in PTENKO ovaries. Serum testosterone and ovarian estradiol were similar between all females. Hence, our results demonstrated AR inactivation mediated protection against PTENKO induced uterine pathology and suggests a potential role for antiandrogens in uterine cancer prevention and treatment.

Free access

R R Tekmal, N Kirma, K Gill, and K Fowler

To test directly the role of breast-tissue estrogen in initiation of breast cancer, we have developed the aromatase-transgenic mouse model and demonstrated for the first time that increased mammary estrogens resulting from the overexpression of aromatase in mammary glands lead to the induction of various preneoplastic and neoplastic changes that are similar to early breast cancer. Continued overexpression of aromatase that leads to increased breast-tissue estrogen contributes to a number of epigenetic changes in mammary tissue such as alteration in the regulation of genes involved in apoptosis, activation of genes involved in cell cycle and cell proliferation, and activation of a number of growth factors. Our current studies show aromatase overexpression is sufficient to induce and maintain early preneoplastic and neoplastic changes in female mice without circulating ovarian estrogen. Preneoplastic and neoplastic changes induced in mammary glands as a result of aromatase overexpression can be completely abrogated with the administration of the aromatase inhibitor, letrozole. Consistent with complete reduction in hyperplasia, we have also seen downregulation of estrogen receptor and a decrease in cell proliferation markers, suggesting aromatase-induced hyperplasia can be treated with aromatase inhibitors. Our studies demonstrate that aromatase overexpression alone, without circulating estrogen, is responsible for the induction of breast hyperplasia and these changes can be abrogated using aromatase inhibitors.

Free access

Daniela Gallo, Elisabetta Mantuano, Manuela Fabrizi, Cristiano Ferlini, Simona Mozzetti, Ilaria De Stefano, and Giovanni Scambia

The study reported here was designed to determine whether a phytoestrogen-containing soy extract (SSE) could negate/overwhelm the inhibitory effects of ICI 182 780 on the growth of estrogen-sustained human breast cancer xenografts (MCF-7), in ovariectomized athymic mice. As expected, estradiol-supplemented tumors did not grow over the study period in ICI 182 780-treated females; concomitant administration of 50 mg/kg per day SSE slightly potentiated the inhibitory activity of the drug, while at 100 mg/kg per day, SSE partially negated ICI 182 780 activity. In keeping with these in vivo outcomes, we observed that the level of cyclin D1 (and progesterone receptor) in MCF-7 xenografts was considerably reduced by ICI 182 780, an effect enhanced by concomitant treatment with 50 SSE, but reduced by the higher dosage (i.e. 100 mg/kg per day). Thrombospondin-1 (TSP-1) and kallikrein 6 (KLK6) levels were also reduced following ICI 182 780, although to a lesser degree; again, combined anti-estrogen and SSE produced a dose-dependent regulation in TSP-1 and KLK6 tumor level, with a further reduction in the mRNA gene expression at 50 SSE (compared with ICI 182 780) and a partial reversion of the drug-induced down-regulation at 100 mg/kg per day. No modulation was detected in the serum concentration of IGF-1 (a potent mitogen for estrogen receptor-positive breast cancer cell lines) either upon treatment with ICI 182 780 or concomitant administration of the anti-estrogen with SSE. In conclusion, results from this study raise concerns about the consumption of isoflavone supplements in conjunction with ICI 182 780 therapy, in postmenopausal women with estrogen-dependent breast cancer.

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N Brünner, M D Johnson, C Holst-Hansen, J F Kiilgaard, E W Thompson, and R Clarke

INTRODUCTION A significant percentage of human breast cancer (HBC) is dependent upon the ovarian hormone estrogen for its onset and progression. The presence or lack of estrogen receptors (ERs) in human breast cancer is an important determinant both of prognosis and of choice of treatment - a poorer prognosis being associated with ER–ve disease. Cell lines established from human breast cancer provide models for breast cancer in various stages of progression (Engel & Young 1978). When grown as tumors in athymic nude mice, these lines represent the major in vivo experimental model for HBC studies (Brünner et al 1987). The ease of both in vitro and in vivo maintenance, the human derivation of the tissue, and the similarities in plasma estrogen levels between ovariectomized nude mice and postmenopausal women (Seibert et al. 1983, Brünner et al. 1986), make the growth of human breast cancer cell lines in nude mice an attractive
Free access

E Enmark and J Å Gustafsson

The recent discovery of a second estrogen receptor, ER&B;, shows that the mechanisms behind the effects of estrogen are far more complicated than previously assumed, and gives unique opportunities to gain a better understanding of these phenomena. ER&B; is expressed in many important target tissues for estrogen, and a better insight into the respective mechanisms of action of ERalpha and ER&B; might give clues concerning the etiology and pathogenesis of for example prostate or ovarian cancer. Development of ERalpha and ER&B; specific ligands may furthermore open up interesting new possibilities for treatment of e.g. postmenopausal symptoms and breast cancer. In this review, we will try to summarize what is known sofar about estrogen receptor &B;, with some emphasis on the human receptor and its expression. We will furthermore try so summarize what is known about different isoforms of the receptor, in view of what is known about isoforms and variants of other receptors, in particular estrogen receptor alpha (ERalpha) and the progesterone receptor (PR).

Acknowledgements

This study was supported by a grant from the Swedish Cancer Society.