Progesterone Receptor A Research Articles

Compartmentalized secretory leukocyte protease inhibitor expression and hormone responses along the reproductive tract of postmenopausal women

Immunity and hormonal responses in the reproductive tissues of postmenopausal women are poorly understood. Secretory leukocyte protease inhibitor (SLPI), a multifunctional antimicrobial protein expressed at mucosal surfaces, is thought to play a key role in infectious and inflammatory contexts. The aim of this study was to measure SLPI production along the female reproductive tract in postmenopausal women with and without hormonal treatment. We additionally quantified estrogen receptor alpha (ERα) and progesterone receptor A (PRA) in these tissues. Expression of SLPI was decreased in the vagina and ectocervix of women under hormonal treatment. Endocervical ERα mRNA expression was increased while this did not reach significance at the protein level. SLPI expression in the endometrium was not influenced by hormonal treatment. We observed attenuated ERα expression in the cervix and endometrium of hormonally treated women, whereas vaginal expression was increased. PRA expression was augmented in the cervix and endometrium and unchanged in the vagina. Taken together, our results indicate that hormonal responses and receptor expression are differentially regulated in vaginal tissue compared with the cervix and endometrium.

Abstract 1315: DNMT and HDAC inhibitors resensitize resistant tumors to antiprogestin therapy in a mouse breast cancer model

Abstract Mouse mammary carcinomas induced by medroxyprogesterone acetate (MPA) are maintained by syngeneic transplantation and tumor variants with different hormone responsiveness have been generated. Tumors which grow without the MPA supply were defined as hormone independent (HI). Most of these tumors regress after antiprogestin (mifepristone, MIF) administration, while others show constitutive resistance to hormone therapy. We have previously demonstrated that responsive tumors show higher levels of progesterone receptor A (PRA) than PRB, while the opposite occurs in resistant tumors, indicating that the PR isoform ratio might be a predictor of antiprogestin responsiveness. We have also demonstrated that in constitutive resistant tumors PRA is silenced by methylation of its promoter, and that treatment with 5azadC (demethylating agent) induces PRA expression and tumors partially recover antiprogestin responsiveness. The aim of this study was to investigate whether the co-treatment with DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors would enhance even more the responsiveness to MIF. For this purpose we investigated the expression of HDAC1 in constitutive resistant tumors and whether treatment of these tumors with 5azadC and trichostatin A (TSA; HDAC inhibitor) restored MIF responsiveness better than 5azadC alone. The constitutive resistant tumor 59-HI showed a higher expression of HDAC1 as compared to the antiprogestin sensititive tumor 59-2-HI as determined by Western blot (p<0,001) and immunohistochemistry, suggesting that these tumors might be candidates to respond to an HDAC inhibitor. 59-HI tumors were implanted sc in BALB/c mice and when tumors were palpable they were treated with a) 5azadC (1 mg/kg/every other day; ip), b) MIF (12 mg/kg/daily; sc), c) 5azadC plus MIF or d) TSA (1 mg/kg/every other day; sc), e) TSA plus 5azadC, f) TSA, 5azadC and MIF, or g) vehicle. Interestingly the co-treatment of 5azadC, TSA and MIF induced a significant inhibitory effect that was even greater than the one induced by 5azadC plus MIF (p<0.001). No inhibitory effects were observed when each compound was used alone or with TSA and MIF. The expression of PR was evaluated in control, 5azadC- and TSA plus 5azadC- treated tumors. An increase in PRA expression was observed by western blot and immunohistochemistry. The increase of PRA was higher with TSA plus 5azadC than with 5azadC alone (p<0,001). In conclusion, we report for the first time that a) constitutive resistant mammary carcinomas show high levels of HDAC1 which might be responsible for histone acetylation within the methylated PRA promoter, b) the combined treatment of demethylating agents and HDAC inhibitors increases the efficiency in both, PR re-expression and antiprogestin sensitivity. These results support our hypothesis that tumors with high levels of PRA are those which respond to antiprogestin treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1315. doi:10.1158/1538-7445.AM2011-1315

Abstract 2294: The nuclear association among ERα – PR – AIB1 is modulated by progestins and antiprogestins in experimental breast cancer

Abstract The nuclear receptor coactivator AIB1 (SRC-3) is intimately associated with hormone action in estrogen receptor (ER)-positive breast cancer, and its overexpression has been associated with early resistance to endocrine therapy. In two models of ER+, progesterone receptor (PR)+ breast cancer, human T47D cells growing in vitro and C4-HD and C4-HI mouse mammary carcinomas maintained by syngeneic transplantations in BALB/c mice, we have shown that progestins induce a nuclear physical association between ERα and PR isoform A (PRA). We hypothesize that this interaction is necessary to induce progestin-induced cell proliferation. While both the pure antiestrogen ICI 182780 (ICI) and the antiprogestin RU486 inhibit tumor growth, only ICI blocked the ERα-PRA nuclear interaction induced by medroxyprogesterone acetate (MPA). RU486 showed an agonist-like effect stimulating the association between both receptors. The aim of this study was to investigate the interaction of ERα with PR isoform B (PRB) in both models and to evaluate the role of AIB1 in progestin-induced proliferation and in RU486-induced inhibition of cell proliferation. MPA (10nM) treatment induced an early increase in the nuclear co-localization between pSer118 ERα and pSer162 PRB in epithelial cells from the mouse model (p<0.001), and between total ERα with pSer162 PRB in T47D cells (p<0.001), as shown by confocal microscopy. By co-immunoprecipitation assays we corroborated that both PR isoforms interact with ERα in the cell nuclei. We also found that MPA increased the nuclear association of pSer294 PR and ERα with AIB1 in the murine epithelial tumor cells (p<0.001). These results were corroborated by co-immunoprecipitation in nuclear extracts from untreated or MPA-treated T47D cells. RU486 (10nM) induced similar ERα-PR interactions as MPA, but no association between PR and AIB1 was observed in RU486-treated cells. Our data support the hypothesis that a nuclear complex of ERα, both PR isoforms, and AIB1 mediates the proliferative effects of MPA. In addition, the results suggest that the lack of association of ERα-PR complexes with AIB1 may explain the antagonist effect of RU486 in these cells, supporting the hypothesis that the inhibitory effects of RU486 are related to genomic events. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2294. doi:10.1158/1538-7445.AM2011-2294

Differential effects of progesterone and genital stimulation on sequential inhibition of estrous behavior and progesterone receptor expression in the rat brain

The effect of genital stimulation, either by vaginocervical stimulation (VCS) using a calibrated vaginal probe combined with manual flank stimulation (FS), or by mounts performed by the male, on the hypothalamus and preoptic area concentration of the progesterone receptors A (PR-A) and B (PR-B) was assessed in ovariectomized (ovx) estrogen-primed rats. VCS/FS or stimulation provided by male mounts, even without intromission, significantly decreased PR-B concentration in the hypoythalamus. Down regulation of PR produced by genital stimulation was quantitatively similar to that elicited by progesterone (P) administration. Bilateral or unilateral transection of the pelvic or the pudendal nerves prevented down regulation elicited by VCS/FS. Repeated VCS/FS elicited lordosis behavior in most ovx estrogen primed rats, but the lordosis intensity was lower than that observed in response to P. P administered to ovx estrogen primed rats, induced sequential inhibition, i.e., failure to display estrous behavior in response to a second P injection (24 h after the initial P injection). VCS/FS failed to elicit sequential inhibition, since rats responded with normal estrous behavior to the second injection of P. This suggests that down regulation by VCS, by contrast with P, failed to inhibit the subpopulation of PR involved in the facilitation of estrous behavior by P.

Estrogen and progesterone receptor isoform distribution through the menstrual cycle in uteri with and without adenomyosis

To test the hypothesis that the expression of the different isoforms of the estrogen receptor alpha (ER-α) and beta (ER-β) and the progesterone receptor A (PR-A) and B (PR-B) would be differentially modulated in uteri with adenomyosis compared with controls and that modulation would be related to the menstrual cycle. Case control, blinded comparison. University department. 54 premenopausal women with and 35 without uterine adenomyosis as the sole pathology. Multiple samples studied using immunohistochemistry for estrogen and progesterone receptors. Histomorphometric analysis of receptor expression. The ER-α expression in the adenomyotic endometrium was different from that of the normal endometrium and the foci in the midsecretory phase of the cycle, but expression of ER-α in the inner and outer myometrium was not statistically significantly different. The ER-β expression was statistically significantly elevated in the adenomyotic functionalis gland during the proliferative phase and throughout the myometrium across the entire menstrual cycle. Expression of PR-A was similar to that of PR-B, with reduced expression in the basalis stroma, and inner and outer myometrium in the adenomyotic samples. The pattern of ER-β, PR-A, and PR-B expression was similar in the endometrial basalis and adenomyotic foci. These data suggest ER-β expression and the lack of PR expression are related to the development and/or progression of adenomyosis and might explain the poor response of adenomyosis-associated menstrual symptoms to progestational agents.

Steroid receptor expression in thymomas and thymic carcinomas

Although protein expressions of glucocorticoid receptor (GR), estrogen receptors (ERα and ERβ), progesterone receptor A (PgR-A), and androgen receptor (AR) were shown to play roles in the growth and differentiation of normal thymus and thymic tumors, to the authors' knowledge their association with patient characteristics and prognosis has yet to be determined. A series of 140 thymic epithelial tumors (57 type A + AB thymomas, 40 type B1 + B2 thymomas, 6 type B3 thymomas, and 37 thymic carcinomas) were examined for GR, ERα, ERβ, PgR-A, and AR expression using immunohistochemistry. In addition, the correlation between expression of these hormone receptors and clinicopathologic factors and overall survival (OS) was assessed. GR and ERβ demonstrated a high rate of expression in thymomas and thymic carcinomas (82.9% and 76.4%, respectively), whereas rates of ERα, PgR-A, and AR expression were low (13.6%, 0.71%, and 23.6%, respectively). A significant correlation (P < .05) was found between ERα expression and tumor size and between ERβ expression and tumor stage. Multivariate analyses revealed that histologic subtype (P = .0039), tumor stage (P = .0012), and GR expression (P = .0025) were significantly correlated with the 10-year OS rate. GR and ERβ demonstrated high rates of expression in thymomas and thymic carcinomas. Furthermore, multivariate analysis revealed that GR expression was associated with better prognosis in patients with surgically resected thymomas and thymic carcinomas.

Sex steroids in uterine endometrial cancers.

Some uterine endometrial cancers conserve estrogen dependency in advancement. However, the concept of advancement in tumor is complicated, because it involves simple growth in primary tumor and secondary spreading. The expression manner of estrogen receptor alpha exon 5 splicing variant, ER beta, progesterone receptor-A (N-terminus deletion mutant) is associated with metastatic potential in uterine endometrial cancers. Increased estrogen-related receptor alpha expression is related to tumor advancement with the loss of estrogen dependency. Steroid receptor coactivator-3 contributes to tumor progression and can be used as a treatment target for advanced uterine endometrial cancers. Estrogen responsive oncogenes, c-jun and c-Ha-ras, are not modi-fied by progestin in uterine endometrial cancer cells and are considered to be an instinct phenotype as such cancers. By contrast, metastatic potential of estrogen-dependent uterine endometrial cancers can be partially controlled by progestin via metastasis-related genes, E-cadherin/catenins, plasminogen activator inhibitor-1, vascular endothelial growth factor. Thus, sex steroids related phenomena are impress-ive in the advancement of uterine endometrial cancers.

Immunohistochemical studies on uterine carcinosarcoma, leiomyosarcoma, and endometrial stromal sarcoma: expression and prognostic importance of ten different markers

Uterine sarcomas are rare and aggressive gynecologic malignancies. In this immunohistochemical (IHC) study, expression of Ki-67, p53, CD10, CD44, desmin, smooth muscle actin, estrogen receptor α (ERα), androgen receptor (AR), progesterone receptor A (PRA), and c-kit and their influence on survival in cases of uterine carcinosarcoma (CS), leiomyosarcoma (LMS), and endometrial stromal sarcoma (ESS) were evaluated. Medical records were reviewed and data collected concerning all uterine sarcomas treated during a 12-year period at Helsinki University Central Hospital. There was sufficient histological material for IHC analysis and slide review in 67 cases. Survival analysis was performed using the Kaplan-Meier method, and median survival times with 95% confidence intervals are given. Survival in cases of LMS was statistically significantly affected by the expression of p53, ERα, and PRA. Striking differences in expression of IHC markers when comparing results with those in earlier studies were the absence of AR immunoreactivity in all uterine sarcomas and low incidence of c-kit (15%; in endometrial stromal sarcoma). None of the markers was statistically significantly associated with survival of ESS and CS patients. The expression of p53, ERα, and PRA in uterine LMS may give prognostic information concerning the behavior of the disease. Hormonal therapy could be recommended as a treatment option in cases of hormone receptor-positive LMS.

Down‐regulated progesterone receptor A and B coinciding with successful treatment of endometrial hyperplasia by the levonorgestrel impregnated intrauterine system

To investigate whether regression of endometrial hyperplasia observed after 3 months of treatment with levonorgestrel impregnated intrauterine system device (LNG-IUS) was sustained after 6 months and whether these effects were still occurring synchronously with extinguished expression of progesterone receptors and increased apoptosis. Retrospective population-based observational study. Six local hospitals and one university hospital in northern Norway. Patients (n = 41) with low and medium risk endometrial hyperplasia. Histopathological treatment response comparing LNG-IUS (n = 25) and standard per oral medroxyprogesterone (n = 16). Expression of progesterone receptor A (PR-A), progesterone receptor B (PR-B), ER-alpha, ER-beta, Bcl-2, BAX, Caspase-3 and metallothionein (MT) were investigated by immunohistochemistry; results were evaluated by a semi-quantitative H-score. Response to progestin treatment. All the LNG-IUS treated patients had therapy response after 6 months. PR-A and PR-B in glands were almost extinguished for IUD users compared to the oral group. Estrogen receptors were also reduced. Co-existent changes in apoptosis were differently modulated in glands and stroma in the two treatment groups. Bcl-2 was different in glands and stroma in responders and non-responders to oral therapy. The study confirms that LNG-IUS can be safely used for 6 months as treatment for endometrial hyperplasia. The clinical effect is accompanied by almost extinguished PR-receptors in glands coinciding with modulation of apoptosis. The results strongly indicate that progestins activate non-classical initiated signaling pathways.

Progesterone Receptor Isoform Expression in the Guinea Pig Myometrium From Normal and Growth Restricted Pregnancies

Despite the increased incidence of preterm labor with intrauterine growth restriction, the mechanisms of the relationship are unclear. In women, functional progesterone withdrawal mediated by changing myometrial progesterone receptor (PR) expression is linked to labor. The objectives of this study were to assess myometrial PR isoform abundance in guinea pig pregnancies associated with growth restriction, induced by disruption of placental blood supply, and in nongravid uterine horns during late gestation and with labor. Myometrial progesterone receptor isoform A (PRA) and B (PRB) abundance were downregulated as labor approached and the expression of both isoforms were markedly higher in the nongravid compared to the gravid uterine horns. The fall in myometrial PRA and B protein levels was delayed in intrauterine growth-restricted (IUGR) pregnancies despite these pregnancies delivering significantly earlier. The results suggest a PR-mediated functional progesterone withdrawal mechanism in guinea pigs that may initiate uterine activation but does not directly stimulate labor and an unexpected role of PR regulation in IUGR-associated pregnancies.

In Utero Exposure to Bisphenol A Shifts the Window of Susceptibility for Mammary Carcinogenesis in the Rat

BackgroundBisphenol A (BPA) is a ubiquitous environmental chemical with reported endocrine-disrupting properties.ObjectiveOur goal in this study was to determine whether prenatal exposure to BPA predisposes the adult rat mammary gland to carcinogenesis.MethodsPregnant rats were treated orally with 0, 25, or 250 μg BPA/kg body weight (BW) from gestation day (GD) 10 to GD21. For tumorigenesis experiments, prenatally exposed female offspring received a single gavage of 7,12-dimethylbenz(a)anthracene (DMBA; 30 mg/kg BW) on postnatal day (PND) 50, or PND100.ResultsPrenatal exposure of the dam to 250 μg BPA/kg BW combined with a single exposure of female offspring to DMBA on PND100, but not on PND50, significantly increased tumor incidence while decreasing tumor latency compared with the control group. Prenatal exposure of the dam to 250 μg BPA/kg BW, in the absence of DMBA to the female offspring, increased cell proliferation and elicited differential effects at the protein level at PND100 compared with PND50. Differentially regulated proteins in the mammary gland included estrogen receptor-α, progesterone receptor-A, Bcl-2, steroid receptor coactivators, epidermal growth factor receptor, phospho-insulin-like growth factor 1 receptor, and phospho-Raf.ConclusionsOur study demonstrates that oral prenatal exposure to BPA increases mammary cancer susceptibility in offspring and shifts the window of susceptibility for DMBA-induced tumorigenesis in the rat mammary gland from PND50 to PND100. These changes are accompanied by differential effects of prenatal BPA exposure on the expression of key proteins involved in cell proliferation.

Enhanced Mammary Progesterone Receptor-A Isoform Activity in the Promotion of Mammary Tumor Progression by Dietary Soy in Rats

Dietary contribution to breast cancer risk, recurrence, and progression remains incompletely understood. Increased consumption of soy and soy isoflavones is associated with reduced mammary cancer susceptibility in women and in rodent models of carcinogenesis. In rats treated with N-methyl-N-nitrosourea, dietary intake of soy protein isolate (SPI) reduced mammary tumor occurrence but increased incidence of more invasive tumors in tumored rats, relative to the control diet casein. Here we evaluated whether mammary tumor progression in tumor-bearing rats lifetime exposed to SPI is associated with deregulated progesterone receptor (PR) isoform expression. In histologically normal mammary glands of rats with invasive ductal carcinoma lesions, PR-A protein levels were higher for SPI- than casein-fed rats, whereas PR-B was undetectable for both groups. Increased mammary PR-A expression was associated with higher transforming growth factor-β1, stanniocalcin-1, and CD44 transcript levels; lower E-cadherin and estrogen receptor-α expression; and reduced apoptotic status in ductal epithelium. Serum progesterone (ng/ml) (CAS: 25.94 ± 3.81; SPI: 13.19 ± 2.32) and estradiol (pg/ml) (CAS: 27.9 ± 4.49; SPI: 68.48 ± 23.87) levels differed with diet. However, sera from rats of both diet groups displayed comparable mammosphere-forming efficiency in human MCF-7 cells. Thus, soy-rich diets may influence the development of more aggressive tumors by enhancing PR-A-dependent signaling in premalignant breast tissues.

BRCA1 selectively regulates the expression of progesterone receptor A in sporadic invasive ductal breast carcinoma

To investigate the expression level of BRCA1, progesterone receptor A (PRA) and B (PRB) in tissue of sporadic invasive ductal breast carcinoma and further statistically analyze the BRCA1 effects on the expression rates of PRA and PRB. Sixty-eight cases of adenosis of breast and sporadic invasive ductal breast carcinoma were selected. The corresponding paraffin-embodied tissues were collected from the archive of Department of Pathology, Nanfang Hospital. The expressions level of BRCA1, PRA and PRB were detected by immunohistochemistry. Wilcoxon two-sample test was used to analyze the differential expression of BRCA1 between adenosis and sporadic invasive ductal breast carcinoma. Chi-square test was used to analyze the effects of BRCA1 on the PRA or PRB expression rate. P value < 0.05 was considered statistically significant. (1) In invasive sporadic ductal breast carcinoma, the positive rate of BRCA1 expression of 60.29% (41/68) was lower than the positive rate of BRCA1 expression at 85.30% (58/68) in adenosis of breast. And the difference of BRCA1 expression between two groups was statistically significant (P < 0.01); (2) In invasive sporadic ductal breast carcinoma, the positive rate of PRA expression for negative BRCA1 expression samples was 81.48% (22/27) and it was higher than the positive rate of PRA expression at 53.66% (22/47) for positive BRCA1 expression samples. And the difference of PRA expression rates between two groups was statistically significant (P < 0.05). It indicated that the expression of BRCA1 affected the expression rate of PRA; In invasive sporadic ductal breast carcinoma, the PRB expression rates between positive and negative BRCA1 expression samples were not statistically significant (P > 0.05). It indicated that BRCA1 had no effect upon the expression rate of PRB. In sporadic breast carcinoma, a negative expression of BRCA1 is selectively associated with a higher expression rate of PRA rather than PRB. Thus BRCA1 selectively regulates the expression of PRA in sporadic breast carcinoma.

Hypermethylation of the progesterone receptor A in constitutive antiprogestin-resistant mouse mammary carcinomas

Most breast carcinomas that are estrogen receptor (ER) and progesterone receptor (PR) positive respond initially to an endocrine therapy, but over time, they develop resistance (acquired hormone resistance). Others, however, fail to respond from the beginning (constitutive resistance). Overcoming hormone resistance is one of the major desirable aims in breast cancer treatment. Using the medroxyprogesterone acetate (MPA)-induced breast cancer mouse model, we have previously demonstrated that antiprogestin-responsive tumors show a higher expression level of PR isoform A (PRA) than PR isoform B (PRB), while tumors with constitutive or acquired resistance show a higher expression level of PRB. The aim of this study was to investigate whether PRA silencing in resistant tumors was due to PRA methylation. The CpG islands located in the PRA promoter and the first exon were studied by methylation-specific PCR (MSP) in six different tumors: two antiprogestin-responsive, two constitutive-resistant, and two with acquired resistance. Only in constitutive-resistant tumors, PRA expression was silenced by DNA methylation. Next, we evaluated the effect of a demethylating agent, 5-aza-2'-deoxycytidine, on PRA expression and antiprogestin responsiveness. In constitutive-resistant tumors, 5-aza-2'-deoxycytidine treatment in vitro and in vivo restored PRA expression and antiprogestin RU-486 responsiveness. Furthermore, high levels of DNA methyltransferase (Dnmts) 1 and 3b were detected in these tumors. In conclusion, our results suggest that methyltransferase inhibitors in combination with antiprogestins may be effective in the treatment of constitutive-resistant carcinomas with a high DNA methyltransferase level.

Induction of progesterone receptor A form attenuates the induction of cytosolic phospholipase A2α expression by cortisol in human amnion fibroblasts

Cytosolic phospholipase A2alpha (cPLA(2alpha), now known as PLA2G4A) is the enzyme catalyzing the formation of the rate-limiting substrate, arachidonic acid, for prostaglandin (PG) synthesis. The increasing expression of PLA2G4A toward term gestation in human amnion fibroblasts is believed to be the crucial event in parturition. Human amnion fibroblasts produce cortisol, progesterone and express glucocorticoid receptor (GR), progesterone receptor A (PGRA) form at term. The roles of progesterone and PGRA in the induction of PLA2G4A by cortisol via GR in the amnion fibroblasts remain largely unknown. Using cultured human term amnion fibroblasts, we found that cortisol induced the expression of PGRA, which was attenuated by inhibiting PG synthesis with indomethacin. Knockdown of PGRA expression or inhibition of endogenous progesterone production with trilostane significantly enhanced the induction of PLA2G4A by cortisol, whereas overexpression of PGRA attenuated the induction of PLA2G4A by cortisol. Although exogenous progesterone did not alter PLA2G4A expression under basal conditions, it attenuated cortisol-induced PLA2G4A expression at concentrations about tenfold higher, which might be achieved by competition with cortisol for GR. In conclusion, PGRA in the presence of endogenous progesterone is a transdominant repressor of the induction of PLA2G4A by cortisol. High level of progesterone may compete with cortisol for GR, thus further inhibiting the induction of PLA2G4A by cortisol. Moreover, increased PG synthesis by cortisol may feed back on the expression of PGRA leading to attenuation of cortisol-induced PLA2G4A expression. The above findings may be pertinent to the inconsistent effects of glucocorticoids on parturition in humans.

Immunocytochemical Localization of Sex Steroid Hormone Receptors in Normal Human Mammary Gland

The sex steroids, estrogens, progesterone, and androgens, all play a role in mammary development and function. To precisely identify the sites of action of these steroids, we studied the localization of the estrogen receptor alpha (ERalpha) and ERbeta, the progesterone receptor A (PRA) and PRB, and androgen receptors (AR) in the normal human mammary gland. Immunocytochemical localization of ERalpha, ERbeta, PRA, PRB, and AR was performed with reduction mammoplasty specimens from premenopausal women. ERalpha, PRA, PRB, and AR were localized mostly to the inner layer of epithelial cells lining acini and intralobular ducts, as well as to myoepithelial cells scattered in the external layer of interlobular ducts. AR was also found in some stromal cells. ERbeta staining was more widespread, resulting in epithelial and myoepithelial cells being labeled in acini and ducts as well as stromal cells. These results suggest that all sex steroids can directly act on epithelial cells to modulate development and function of the human mammary gland. Estrogens and androgens can also indirectly influence epithelial cell activity by an action on stromal cells.

Analysis of the Expression of Progesterone Receptor A (PRA) and B (PRB) in the Endometrium of Women with Endometriosis

Analysis of the Expression of Progesterone Receptor A (PRA) and B (PRB) in the Endometrium of Women with Endometriosis

Effects of Progesterone and Its Antagonist Mifepristone on Progesterone Receptor A Expression in Human Umbilical Vein Endothelial Cells

Effects of female steroid hormones on endothelial cells are gaining increased importance due to several studies on the effects of hormonal treatment on cardiovascular risk. Recent data argue for an improvement of endothelium-derived relaxation and impaired vascular contraction by estradiol, whereas progesterone and testosterone might entail contrary effects. So far, gestagenic influence on endothelial cell physiology is poorly understood. Human umbilical vein endothelial cells (HUVECs) exposed to the female sex hormones estradiol and progesterone show expression of estrogen receptor-β (ERβ) and progesterone receptor A (PR-A), and are negative for ERα and PR-B. The aim of this study was to analyze the expression and stimulation of PR-A and -B in HUVECs after stimulation with progesterone and PR antagonists that are commercially available. PR-B expression or upregulation was abrogated after application of progesterone or antagonists to HUVECs. Expression of PR-A could be significantly upregulated with progesterone and mifepristone. Unexpectedly, stimulation with the progesterone antagonist RU486 (mifepristone) was accomplished by an upregulation of PR-A expression in our study. We conclude that gestagenic effects on HUVECs independent of modulators are mediated via the PR-A.

Nuclear Progesterone Receptor Expression in the Human Fetal Membranes and Decidua at Term Before and After Labor

To explore how progesterone affects human pregnancy, we identified the progesterone target cells within the fetal membranes (amnion, chorion, and decidua) at term by assessing the extent of expression and localization of the nuclear progesterone receptors, progesterone receptor-A and progesterone receptor-B. Fetal membranes (separated into amnion and chorion-decidua) were obtained after term cesarean deliveries performed before (n = 7) and after (n = 7) labor onset. Nuclear progesterone receptor expression was determined by the abundance of nuclear progesterone receptor mRNAs (by quantitative reverse transcriptase-polymerase chain reaction) and proteins (by western blotting). Localization of nPRs was determined by immunohistochemistry. Progesterone receptor-A and progesterone receptor-B mRNA and protein levels were highest in the chorion-decidua and did not change in association with labor. Nuclear progesterone receptor mRNAs and proteins were barely detectable in amnion. Nuclear progesterone receptor immunostaining was detected only in the nucleus of decidual cells. These findings suggest that the decidua, and not the amnion and chorion, is a direct target for nuclear progesterone receptor-mediated progesterone actions during human pregnancy.

Oral exposure to bisphenol a increases dimethylbenzanthracene-induced mammary cancer in rats.

BackgroundBisphenol A (BPA) is widely used in the manufacture of polycarbonate plastics, including infant formula bottles.ObjectivesBased on the reported endocrine disruptor activity of this polyphenol, we hypothesized that exposure to BPA early in life would elicit developmental changes in the mammary tissue and cause a predisposition for mammary cancer.MethodsWe exposed neonatal/prepubertal rats to BPA via lactation from nursing dams treated orally with 0, 25, and 250 μg BPA/kg body weight/day. For tumorigenesis studies, female offspring were exposed to 30 mg dimethylbenzanthracene (DMBA)/kg body weight at 50 days of age.ResultsThe combination of DMBA treatment with lactational exposure to BPA demonstrated a dose-dependent increase in mammary tumor multiplicity and reduced tumor latency compared with controls. In the absence of DMBA treatment, lactational BPA exposure resulted in increased cell proliferation and decreased apoptosis at 50 but not 21 days postpartum (shortly after last BPA treatment). Using Western blot analysis, we determined that steroid receptor coactivators (SRCs) 1–3, Akt, phosphorylated Akt, progesterone receptor A (PR-A), and erbB3 proteins were significantly up-regulated at 50 days of age.ConclusionsThe data presented here provide the first evidence that maternal exposure to BPA during lactation increases mammary carcinogenesis in a DMBA-induced model of rodent mammary cancer. Changes in PR-A, SRC 1–3, erbB3, and Akt activity are consistent with increased cell proliferation and decreased apoptosis playing a role in mammary cancer susceptibility. These alterations provide an explanation of enhanced mammary carcinogenesis after lactational BPA exposure.