Androgens inhibit the stimulatory action of 17β-estradiol on normal human breast tissue in explant cultures (original) (raw)
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Breast Cancer Research and Treatment, 1988
This study describes the inhibitory effect of 5a-dihydrotestosterone (5a-DHT) and its precursors testosterone (T) and androst-4-ene-3,17-dione (A4-DIONE) on the growth of the estrogen-sensitive human breast cancer cell line ZR-75-1. In the absence of estrogens, cell proliferation measured after a 12-day incubation period was 50-60% inhibited by maximal concentrations of 5a-DHT, T, or A4-DIONE with half-maximal effects (ICs0 values) observed at 0.10, 0.15 and 15 nM, respectively. This growth inhibition by androgens was due to an increase in generation time and a lowering of the saturation density of cell cultures. The antiestrogen LY156758 (300 nM) induced 25-30% inhibition of basal cell growth, its effect being additive to that of 5a-DHT. The mitogenic effect of 1 nM estradiol (E2) was completely inhibited by increasing concentrations of 5a-DHT with a potency (IC50 = 0.10 nM) similar to that measured when the androgen was used alone. E2 had a more rapid effect on cell proliferation than 5a-DHT, the latter requiring at least 5 to 6 days to exert significant growth inhibition. As found in the absence of estrogens, maximal inhibition of cell proliferation in the presence of E2 was achieved by the combination of the antiestrogen and 5a-DHT. Supraphysiological concentrations of E2 (up to 1/xM) were needed to completely reverse the growth inhibitory effect of a submaximal concentration of 5a-DHT (1 nM). The antiproliferative effect of androgens was competitively reversed by the antiandrogen hydroxyflutamide, thus indicating an androgen receptormediated mechanism. The present data suggest the potential benefits of an androgen-antiestrogen combination therapy in the endocrine management of breast cancer.
Role of androgens in proliferation and differentiation of mouse mammary epithelial cell line HC11
Journal of Endocrinology, 2000
Androgens have been found in mammary epithelium and in milk throughout the cycle of the mammary gland in vivo. The aim of this study was to investigate the possible role of these substances in mammary epithelial growth and differentiation in the mouse HC11 cell line. Cells were stimulated with testosterone, dihydrotestosterone, androstenedione and 5 -androstane-3 ,17 -diol at concentrations ranging between 0·3 nM and 30 nM. Cyproterone acetate or flutamide, androgen receptor antagonists, (3 µM) were used to block specific androgen effects. Proliferative effects were measured by an MTT (tetrazolium blue) conversion test and [ 3 H]thymidine uptake. HC11 cells were transfected with p cCAT, a chimeric rat -casein gene promoter-chloramphenicol acetyl transferase (CAT) gene construct and CAT ELISA was used to determine gene expression. RT-PCR was performed to detect androgen receptor expression. After 24, 48 and 72 h androgens significantly (P<0·05) increased proliferation. Androgen antagonists significantly (P<0·05) reduced the proliferative effects. Furthermore androgens potentiated the lactogenic effect of prolactin, insulin and dexamethasone (P<0·05). Finally, the androgen receptor gene was expressed in both proliferating and differentiated HC11 cells. These observations lead us to hypothesize an activity of this class of steroids in mammary physiology. In particular, androgens stimulate cell proliferation and -casein gene expression; this influence appears to be mediated by androgen receptors.
1998
Both endogenous and exogenous estrogen exposure is associated with an increased breast cancer risk. In some studies, elevated serum testosterone levels have also been linked to an increased breast cancer risk. Estrogen alone or combined with progesterone induces high mammary tumor incidences in various strains of both male and female rats. Mammary gland ductal adenocarcinomas were induced after 17β-estradiol (E 2 ) and testosterone propionate (TP) treatment in male Noble rats. Tumor incidence was 100% after 8-9 months of treatment. Such neoplasms were not detected after either estrogen or androgen exposure alone within this time period. TP alone caused disruption of mammary gland ducts and proliferation of stromal tissue, while E 2 treatment alone induced both ductal epithelial growth and nodular atypical hyperplasia. To study the interaction of these hormones in mammary tumorigenesis, sex hormone receptors were characterized in mammary glands of Noble rats. Estrogen receptor-α (ER) was detected in age-matched, untreated mammary gland epithelium; in most early atypical hyperplastic lesions appearing after E 2 and E 2 ⍣ TP treatment and in E 2 ⍣ TP-induced mammary tumors. Two major ER putative isoforms, 116 and 120 kDa, were detected in E 2 -and E 2 ⍣ TP-treated mammary glands, and in the induced tumors. A 54 kDa ER protein was found in untreated and TP-treated mammary glands, and in the induced tumors. Both progesterone receptor-B (PR-B) and PR-A2, as well as androgen receptor-B (AR-B) and AR-A isoforms were markedly elevated in all E 2 ⍣ TP-induced mammary tumors. However, the levels of both PR and AR were very low in mammary glands of E 2 -and E 2 ⍣ TP-treated male rats. Low and moderate levels of AR and PR, respectively, were detected in most atypical hyperplastic lesions induced by E 2 -and E 2 ⍣ TP-treated mammary glands. These results suggest that androgens may interact with either AR or PR, and perhaps both receptors, in E 2 ⍣ TP-induced mammary glands and the induced tumors to effect the reduction in latency period, enhance tumor size, and increase incidence to 100%.
Estrogen receptors in androgen induced breast tumor regression
Cancer Research
The hormone-dependent 7,1 2-dimethylbenz(a)anthracene rat mammary tumor has been shown to regress when ad ministered pharmacological doses of testosterone pro pionate. Tumor regression was correlated with estrogen receptor before and 15 to 20 days following testosterone therapy. A dramatic decline of receptor occurred in all regressing tumors, whereas those administered sesame oil alone maintained both growth and receptor content. Although receptor in regressing tumors was significantly less than in the untreated biopsies, the small amount of remaining receptor maintained the same binding affinity to estradiol, showing that testosterone affects the n umber and not estrogen affinity of the estrogen receptor. These studies suggest that testosterone depletion of estrogen receptor may be causally related to tumor regression.
Breast cancer: from estrogen to androgen receptor
2002
To investigate the link existing between androgens and human breast cancer, the hormonal milieu present in pre-and postmenopausal women has been translated in an in vitro model utilizing a hormone dependent breast cancer cell line MCF-7 exposed to DHEA, DHEAS, androstenediol, T, DHT with or w/o E 2. DHEAS and androstenediol stimulate the growth of MCF-7 cell line but reduce cell proliferation induced by E 2 (1 nM). T and DHT (1 Á/100 nM) instead inhibit MCF-7 cell proliferation independently on E 2 presence. When we focused our study on the most powerful androgen, DHT alone (100 nM) consistently inhibits MCF-7 cell proliferation by 50% of the basal growth rate and counteracts E 2 proliferative action by 68%. These data correlate well with cell cycle analysis showing an enhanced number of cells in G 0 /G 1 phase after 6 days of DHT treatment. Upon prolonged DHT exposure, Western blotting analysis shows a markedly increased AR content, while immunohistochemistry indicates that it was mostly translocated into the nucleus. So we assumed that the enhanced activation of the AR might inhibit MCF-7 cells proliferation. This assumption is corroborated by the fact that the inhibitory effects induced by DHT on MCF-7 cell proliferation are abrogated in the presence of hydroxyflutamide. Therefore to better investigate the role of AR in inhibiting E 2 action at genomic level, MCF-7 cells were transiently cotransfected with the reporter plasmid XETL carrying firefly luciferase sequence under the control of an estrogen responsive element and the full length AR or with an AR carrying a mutation (Cis 574 0/Arg 574) which abolishes its binding to DNA. The over-expression of the AR markedly decreases E 2 signalling which furthermore appears inhibited by simultaneous exposure to DHT but reversed by addition of hydroxyflutamide. The inhibitory effect was no longer noticeable when MCF-7 cells were cotransfected with XETL and the mutant AR. Taken together these data demonstrate that gonadal androgens antagonize MCF-7 proliferation induced by E 2. This seems to be related to the inhibitory effects of the over-expressed AR on E 2 genomic action.
Journal of the Society for Gynecologic Investigation, 2000
OBJECTIVES: Oral contraceptive (OC) therapy has long been known to produce hypoandrogenemia. However, androgens are not part of any OC therapy available to women. This project was designed to evaluate the effects of low-estradiol containing OC, with or without methyltestosterone (MT), on cell proliferation and progesterone receptor (PgR) expression in mammary gland epithelia of virgin female rats. METHODS: Sixty rats were divided into four groups. One group received OCs, whereas a second group received OC plus MT. A third group of rats was treated with an antiandrogen to mimic the hypoandrogenemic effects caused by OC therapy. All treated groups were compared with age-matched untreated controls. RESULTS: After 15 weeks of treatment, no inflammatory, precancerous, or cancerous lesions were observed in any treatment group. OC plus MT therapy caused significant suppression of epithelial proliferation, a reduction in the number ofproliferating cell nuclear antigen-labeled cells, and an increase in the number of PgR-labeled cells. CONCLUSIONS: Our results suggest that a medication containing an estrogen-progestin-androgen combination has antiprolfterative effects in mammary glands ofexperimental animals that could prove to have breast-protective potential in women. (J Soc Gynecol Investig 2000; 7:257-65) Copyright © 2000 by the Society for Gynecologic Investigation. coca KEY WORDS: Mammary glands, oral contraceptives, androgens, cell proliferation, progesterone receptor. omen who develop breast cancer in their pre-studies indicate that both estrogen excess and androgen defimenopausal years tend to have subnormal serum ciency may be involved in male breast cancer. In fact, the levels of adrenal androgens. Consequently, it has strongest association between aberrant endocrine function and been proposed that androgens, possibly by acting through the male breast cancer occurs in patients with Klinefelter's synandrogen receptor (AR), may oppose estrogen-stimulated cell drome, who have an approximate 3% lifetime risk of develgrowth in premenopausal years.1 Epidemiology, genetics, in oping breast cancer.2 Also, heritable genetic mutations in the vitro work, and anticancer therapy support the hypothesis that AR gene are associated with a predisposition to male breast circulating androgens protect against breast cancer risk. Becancer development.3 These findings are supported by in vitro cause breast cancer in men is rare and affects <0.1% of the molecular studies on tumor cells, which provide evidence for male population, gender incidence supports a beneficial effect a beneficial effect of androgens. The proliferation of ARof androgens. Epidemiologically, retrospective case-control positive malignant mammary cell lines (MFM-223) can be inhibited with androgen treatment.4 Finally, anticancer ther-Fronm Pathology Associates International, Advance North Carolina; the Department of apy supports androgen's beneficial action, because for years Com-iparative Medici(
Effects of estradiol and progestogens on human breast cells: regulation of sex steroid receptors
Taiwanese journal of obstetrics & gynecology, 2013
To examine the effects of 17β-estradiol (E2) and progestogens, used in hormone therapy, on estrogen receptors (ER), progesterone receptors (PR), and human breast tumor cell growth. MCF-7 cells were incubated in pure E2 (1 nM and 10 nM) as well as in E2 in conjunction with 10 nM progestogens, including progesterone (P4), medroxyprogesterone acetate (MPA), norethisterone acetate (NET), and cyproterone acetate (CPA). Cell proliferation, apoptosis, expression of caspase-3, and both ER and PR isoforms were evaluated. Caspase-3 was significantly diminished in cultures with only E2, whereas ERα significantly increased. A significant increase of caspase-3 in addition to the entire abolishment of E2-induced augmentation of ERα was observed in 1 nM E2 plus MPA and 10 nM E2 plus NET, whereas PR isoform B (PRB) was significantly increased. The ratios of apoptosis: proliferation significantly increased in 1 nM E2 plus progestogens (except P4) and 10 nM E2 plus NET. The changes of the PRA/PRB rat...
Faseb Journal, 2000
This study investigated the effect of sex steroids and tamoxifen on primate mammary epithelial proliferation and steroid receptor gene expression. Ovariectomized rhesus monkeys were treated with placebo, 17 estradiol (E2) alone or in combination with progesterone (E2/P) or testosterone (E2/T), or tamoxifen for 3 days. E2 alone increased mammary epithelial proliferation by ϳsixfold (P<0.0001) and increased mammary epithelial estrogen receptor (ER␣) mRNA expression by ϳ50% (P<0.0001; ER mRNA was not detected in the primate mammary gland). Progesterone did not alter E2's proliferative effects, but testosterone reduced E2-induced proliferation by ϳ40% (P<0.002) and entirely abolished E2-induced augmentation of ER␣ expression. Tamoxifen had a significant agonist effect in the ovariectomized monkey, producing a ϳthreefold increase in mammary epithelial proliferation (P<0.01), but tamoxifen also reduced ER␣ expression below placebo level. Androgen receptor (AR) mRNA was detected in mammary epithelium by in situ hybridization. AR mRNA levels were not altered by E2 alone but were significantly reduced by E2/T and tamoxifen treatment. Because combined E2/T and tamoxifen had similar effects on mammary epithelium, we investigated the regulation of known sex steroid-responsive mRNAs in the primate mammary epithelium. E2 alone had no effect on apolipoprotein D (ApoD) or IGF binding protein 5 (IGFBP5) expression, but E2/T and tamoxifen treatment groups both demonstrated identical alterations in these mRNAs (ApoD was decreased and IGFBP5 was increased). These observations showing androgen-induced down-regulation of mammary epithelial proliferation and ER expression suggest that combined estrogen/androgen hormone replacement therapy might reduce the risk of breast cancer associated with estrogen replacement. In addition, these novel findings on tamoxifen's androgen-like effects on primate mammary epithelial sex steroid receptor expression suggest that tamoxifen's protective action on mammary gland may involve androgenic effects.-Zhou, J., Ng, S., Adesanya-Famuiya, O., Anderson, K., Bondy, C. A. Testosterone inhibits estrogen-induced mammary epithelial proliferation and suppresses estrogen receptor expression. FASEB
Effect of Testosterone on Proliferation Markers and Apoptosis in Breasts of Ovariectomized Rats
Revista Brasileira de Ginecologia e Obstetrícia / RBGO Gynecology and Obstetrics
Objective To investigate the action of testosterone (T), isolated or associated with estradiol benzoate (EB), on the proliferation markers and apoptosis of breasts of ovariectomized rats. Methods A total of 48 castrated female Wistar rats were divided into 6 groups, and each of them were submitted to one of the following treatments for 5 weeks: 1) control; 2) EB 50 mcg/day + T 50 mcg/day; 3) T 50mcg/day; 4) EB 50 mcg + T 300 mcg/day; 5) T 300 mcg/day; and 6) EB 50 mcg/day. After the treatment, the mammary tissue was submitted to a histological analysis and immunoexpression evaluation of proliferation markers (proliferating cell nuclear antigen, PCNA) and apoptosis (caspase-3). Results There was a statistically significant difference among the groups regarding microcalcifications and secretory activity, with higher prevalence in the groups treated with EB. There was no difference among the groups regarding atrophy, but a higher prevalence of atrophy was found in the groups that rece...
Endocrinology, 1997
Sex steroids control the proliferation of their target cells through two different pathways: 1) proliferative response (Step-1); and 2) inhibition of cell proliferation (Step-2). Mechanisms of cell proliferation regulation are incompletely understood; however, there is general agreement with the notion that sex steroid receptors play an important role in the control of the proliferation of sex steroid target cells. To test this hypothesis, a full human androgen receptor (AR) vector was transfected into human breast cancer MCF7 cells. The cloned cells that stably express the AR, called MCF7-AR1 cells, contained approximately five times more AR than the wild-type MCF7 cells from which they were derived. These AR-transfected cells retained their capacity to proliferate when estrogens were added to 10% charcoal-dextran stripped human serum but did not acquire the abil-