Regulation of progesterone receptor messenger ribonucleic acid by progestin in human endometrial stromal cells

The endometrial proteomic profile around the time of embryo implantation†

Embryo implantation is an intricate process which requires competent embryo and receptive endometrium. The failure of endometrium to achieve receptivity is a recognized cause of infertility. However, due to multiplicity of events involved, the molecular mechanisms governing endometrial receptivity are still not fully understood. Traditional one-by-one approaches, including western blotting and histochemistry, are insufficient to examine the extensive changes of endometrial proteome. Although genomics and transcriptomics studies have identified several significant genes, the underlying mechanism remains to be uncovered owing to post-transcriptional and post-translational modifications. Proteomic technologies are high throughput in protein identification, and they are now intensively used to identify diagnostic and prognostic markers in the field of reproductive medicine. There is a series of studies analyzing endometrial proteomic profile, which has provided a mechanistic insight into implantation failure. These published studies mainly focused on the difference between pre-receptive and receptive stages of endometrium, as well as on the alternation of endometrial proteomics in women with reproductive failure. Here, we review recent data from proteomic analyses regarding endometrium around the time of embryo implantation and propose possible future research directions.

Aberrant endometrial steroid receptor expression in in-vitro maturation cycles despite hormonal luteal support: A pilot study

Clinical outcomes of fresh embryo transfer in non-hCG triggered in vitro maturation (IVM) cycles are inferior compared to vitrified-warmed embryo transfer. This is a prospective observational pilot study in a consecutive cohort of 31 polycystic ovary syndrome (PCOS) patients and 37 normo-ovulatory egg donors who underwent IVM without fresh embryo transfer between July 2009 and June 2014. All subjects received 150 IU of highly purified menotropin (HP-hMG) daily for three days. On cycle day 6, all patients started transdermal oestradiol (E2) at a daily dose of 9 mg. There was no human chorionic gonadotropin (hCG) trigger before oocyte retrieval (OR). Vaginal micronized progesterone was commenced on the evening after OR, at a daily dose of 600 mg. Additional luteal phase support (LPS) was administered as follows: Group A: no additional LPS; Group B: 1500 IU of hCG administered 4 h after OR and Group C: 5000 IU of hCG administered 4 h after OR + an additional injection of 5000 IU of hCG 1 day before endometrial biopsy. Endometrial biopsy for histology and immunohistochemistry (IHC) was performed on day 5 or 6 after OR. Instead of being downregulated, both PR-B and ERα in endometrial glands and stroma were moderately to strongly expressed in all three protocols, suggesting that the mid-luteal histological signature of endometrial receptivity is deficient in a non-hCG-triggered IVM cycle. Poor clinical outcomes after fresh embryo transfer following IVM are probably related to inappropriate endometrial development which may be linked to the short follicular phase of IVM cycles.

The mammalian decidual cell evolved from a cellular stress response

Among animal species, cell types vary greatly in terms of number and kind. The number of cell types found within an organism differs considerably between species, and cell type diversity is a significant contributor to differences in organismal structure and function. These observations suggest that cell type origination is a significant source of evolutionary novelty. The molecular mechanisms that result in the evolution of novel cell types, however, are poorly understood. Here, we show that a novel cell type of eutherians mammals, the decidual stromal cell (DSC), evolved by rewiring an ancestral cellular stress response. We isolated the precursor cell type of DSCs, endometrial stromal fibroblasts (ESFs), from the opossum Monodelphis domestica. We show that, in opossum ESFs, the majority of decidual core regulatory genes respond to decidualizing signals but do not regulate decidual effector genes. Rather, in opossum ESFs, decidual transcription factors function in apoptotic and oxidative stress response. We propose that rewiring of cellular stress responses was an important mechanism for the evolution of the eutherian decidual cell type.

From epidemiology and neurodevelopment to antineoplasticity. Medroxyprogesterone reduces human glial tumor growth in vitro and C6 glioma in rat brain in vivo

OBJECTIVE

Glial tumor growth may accelerate during gestation, but epidemiological studies consistently demonstrated that parousity reduces life long risk of glial tumors. Pregnancy may also accelerate growth of medulloblastoma and meningioma, but parousity does not confer protection against these tumors. We were the first to show that medroxyprogesterone acetate (MPA) reduces rat C6 glioma growth in vitro. Now we aimed to determine the effects of MPA on human brain cancers (particularly glioblastoma) in vitro and C6 glioma in vivo.

PATIENTS AND METHODS

We evaluated the effects of MPA on: i) monolayer growth of human U87 and U251 glioblastoma, ii) 3D-spheroid growth and invasion of C6 rat glioma and human U251 glioma, iii) interactions with PI3-Kinase inhibitors and coxsackie-adenovirus receptor (CAR) in modifying 3D-spheroid invasion of glioma.

RESULTS

MPA at low doses (3.25-13 μM) insignificantly stimulated and at high doses (above 52 μM) strongly suppressed the growth of human U87 and U251 cells in vitro. MPA also binds to glucocorticoid receptors similar to dexamethasone (Dex) and unexpectedly, PI3-Kinase inhibitors at low doses suppressed anti-invasive efficacies of MPA and Dex. MPA exerted higher invasion-inhibitory effects on CAR-expressing human glioma cells. Lastly, MPA suppressed growth of C6 glioma implanted into rat brain.

CONCLUSION

Progesterone analogues deserve to be studied in future experimental models of high grade glial brain tumors.

Differential expressions of estrogen and progesterone receptors in endometria and cyst walls of ovarian endometrioma from women with endometriosis and their responses to depo-medroxyprogesterone acetate treatment

BACKGROUND

Depo-medroxyprogesterone acetate (DMPA) is an injectable progestin contraceptive that provides a highly effective reduction of pelvic pain in women with endometriosis. Despite its wide use to treat pain associated with endometriosis, its precise mechanisms of action remain unclear. The aims of this study were to investigate the differential expressions of estrogen receptors (ERs), and progesterone receptors (PRs) in endometria and ovarian endometrioma cyst walls of women with endometriosis with and without DMPA treatment.

METHODS

Endometria and cyst walls of endometrioma were obtained from 25 to 45 year-old women who suffered from endometriosis and had ovarian endometrioma with the size ≥3 cm. The expression levels of ERs and PRs and the numbers of ER- and PR-positive cells before and after treatment with DMPA were evaluated by Western blot, real-time PCR, and immunohistochemistry.

RESULTS

The levels of ERα and ERβ expression, their corresponding mRNAs, and numbers of ERα- and ERβ-immunoreactive cells in stroma and glands of endometria of the DMPA group were significantly decreased when compared with those of the untreated groups (p < 0.05). In contrast, the levels of PRA/B expression and numbers of PRA/B positive cells in stroma and number of PRB positive cells in stroma and endometrial glands were significantly increased in endometria of the DMPA group when compared with those of the untreated groups. However, in cyst wall the expression levels of these proteins, their corresponding mRNAs, and immonoractive cells were low compared to those in endometria, and DMPA-treatment did not cause any significant changes in these parameters.

CONCLUSION

These data indicated that DMPA could upregulate the expressions of PRA/B and down-regulate ERα and ERβ in endometria but not in cyst walls from women with endometriosis.

Inflammatory Stimuli Increase Progesterone Receptor-A Stability and Transrepressive Activity in Myometrial Cells

The steroid hormone progesterone acting via the nuclear progesterone receptor (PR) isoforms, progesterone receptor A (PR-A) and progesterone receptor B (PR-B), is essential for the maintenance of uterine quiescence during pregnancy. Inhibition of PR signaling augments uterine contractility and induces labor. Human parturition is thought to be triggered by modulation of PR signaling in myometrial cells to induce a functional progesterone withdrawal. One mechanism for functional progesterone withdrawal is increased abundance of PR-A, which decreases progesterone responsiveness by inhibiting the transcriptional activity of PR-B. Human parturition also involves tissue-level inflammation within the myometrium. This study examined the control of PR-A abundance and transrepressive activity in myometrial cells and the role of the inflammatory stimuli in the form of interleukin-1β (IL-1β) and lipopolysaccharide (LPS) in these processes. We found that abundance of PR-A was markedly increased by progesterone and by exposure to IL-1β and LPS via posttranslational mechanisms involving increased PR-A protein stability. In contrast, progesterone decreased abundance of PR-B by increasing its rate of degradation. Together, progesterone and proinflammatory stimuli induced a PR-A-dominant state in myometrial cells similar to that observed in term laboring myometrium. IL-1β and LPS also increased the capacity for PR-A to inhibit the transcriptional activity of PR-B. Taken together, our data suggest that proinflammatory stimuli increase the steady-state levels of PR-A and its transrepressive activity in myometrial cells and support the hypothesis that tissue-level inflammation triggers parturition by inducing PR-A-mediated functional progesterone withdrawal.

Agonist-Dependent Downregulation of Progesterone Receptors in Human Cervical Stromal Fibroblasts

Progesterone (P(4)) maintains uterine quiescence during the majority of pregnancy, whereas diminished progesterone receptor (PR) expression and/or activity (ie, functional P(4) withdrawal) promotes parturition. To investigate the regulation of PR expression in cervical stroma, fibroblasts from premenopausal hysterectomy specimens were prepared. Greater than 99% of the cultures were vimentin positive (mesenchymal cell marker) with only occasional cytokeratin-8 positivity (epithelial cell marker) and no evidence of CD31-positive (endothelial cell marker) cells. Cells were immunolabeled with antibodies directed against PRs (PR-A and PR-B), estrogen receptor α (ER-α), and glucocorticoid receptor-α/β (GR-α/β). All cells were uniformly immunopositive for ER-α and GR-α/β but did not express PRs. Incubation of cells with 10(-8) mol/L 17β-estradiol induced a time-dependent increase in PR-A and PR-B messenger RNAs (mRNAs) by quantitative real-time polymerase chain reactions and proteins by immunoblotting and immunofluorescence. Incubation of cervical fibroblasts with PR ligands (medroxyprogesterone acetate or Org-2058) downregulated PR-A and PR-B levels. Coincubation of cells with PR ligands plus RU-486, a PR antagonist, partially abrogated agonist-induced receptor downregulation. Dexamethasone, a pure glucocorticoid, had no inhibitory effect on PR expression. These results indicate that progestins and estrogens regulate PR expression in cervical fibroblasts. We postulate that hormonal regulation of PR expression in the cervical stroma may contribute to functional P(4) withdrawal in preparation for parturition.

Cyclic decidualization of the human endometrium in reproductive health and failure

Decidualization denotes the transformation of endometrial stromal fibroblasts into specialized secretory decidual cells that provide a nutritive and immunoprivileged matrix essential for embryo implantation and placental development. In contrast to most mammals, decidualization of the human endometrium does not require embryo implantation. Instead, this process is driven by the postovulatory rise in progesterone levels and increasing local cAMP production. In response to falling progesterone levels, spontaneous decidualization causes menstrual shedding and cyclic regeneration of the endometrium. A growing body of evidence indicates that the shift from embryonic to maternal control of the decidual process represents a pivotal evolutionary adaptation to the challenge posed by invasive and chromosomally diverse human embryos. This concept is predicated on the ability of decidualizing stromal cells to respond to individual embryos in a manner that either promotes implantation and further development or facilitates early rejection. Furthermore, menstruation and cyclic regeneration involves stem cell recruitment and renders the endometrium intrinsically capable of adapting its decidual response to maximize reproductive success. Here we review the endocrine, paracrine, and autocrine cues that tightly govern this differentiation process. In response to activation of various signaling pathways and genome-wide chromatin remodeling, evolutionarily conserved transcriptional factors gain access to the decidua-specific regulatory circuitry. Once initiated, the decidual process is poised to transit through distinct phenotypic phases that underpin endometrial receptivity, embryo selection, and, ultimately, resolution of pregnancy. We discuss how disorders that subvert the programming, initiation, or progression of decidualization compromise reproductive health and predispose for pregnancy failure.

Gene x environment interactions impact endometrial function and the menstrual cycle: PROGINS, life history, anthropometry, and physical activity

OBJECTIVES

We assessed the impact of a high frequency, functionally significant allelic variant of the progesterone receptor gene (PROGINS) on endometrial function and menstrual cycle characteristics. Further we asked whether PROGINS moderates the impact of life history characteristics, anthropometric measures, and physical activity on endometrial function.

METHODS

Fifty-two women were genotyped for the PROGINS variant, provided life history information, and had anthropometric measurements made. Women monitored their menstrual bleeding for three cycles, performed mid-cycle urinary ovulation tests, and recorded physical activity. A subset of women provided daily saliva samples and had mid-luteal endometrial thickness measurements taken during the third menstrual cycle. Salivary progesterone was assayed using ELISAs. The direct impact of PROGINS on endometrial and menstrual cycle characteristics was determined via independent t-tests with Bonferroni correction. Interactions between PROGINS and covariates were assessed by moderated regression.

RESULTS

PROGINS did not directly impact any indicator of endometrial function. However, PROGINS caused an increase in menstrual cycle length with increasing mid-luteal progesterone levels; the opposite relationship was present in noncarriers (P < 0.05). Additionally, PROGINS interacted with four of six anthropometric measures (BMI, waist circumference, height, and waist-hip ratio) to impact endometrial function, however, interactions between PROGINS and life history variables, or physical activity was limited.

CONCLUSIONS

The gene x environment interactions we report suggest that PROGINS alters endometrial sensitivity to maternal energetic condition. Thus, the possibility of genetically-based variation in sensitivity to energetic stress should be considered in future adaptive models of women's reproduction.

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

OBJECTIVE

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.

DESIGN

Case control, blinded comparison.

SETTING

University department.

PATIENT(S)

54 premenopausal women with and 35 without uterine adenomyosis as the sole pathology.

INTERVENTION(S)

Multiple samples studied using immunohistochemistry for estrogen and progesterone receptors.

MAIN OUTCOME MEASURE(S)

Histomorphometric analysis of receptor expression.

RESULT(S)

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.

CONCLUSION(S)

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.

Altered gene expression profile in vaginal polypoid endometriosis resembles peritoneal endometriosis and is consistent with increased local estrogen production

BACKGROUND

In a university hospital setting, a 25-year-old woman presented with large vaginal and cervical polyps. Past medical history was significant for stage IV endometriosis. Polypectomy was performed and the polyps were histologically consistent with endometriosis. Gene expression was compared with control vaginal tissue to assess if the altered gene expression profile was similar to peritoneal endometriosis.

METHODS AND RESULTS

Using quantitative reverse transcription, real-time PCR, estrogen receptor-β expression was found to be upregulated 10-fold while estrogen receptor-α expression was downregulated 5-fold in the vaginal polyp relative to control vaginal tissue. The estrogen-synthesizing enzyme aromatase was upregulated 8-fold and 3β-hydroxysteroid dehydrogenase was upregulated 400-fold in the polyp. Immunohistochemical staining revealed altered cell type localization for progesterone receptor in the polyp and increased cell proliferation in polyp stromal cells relative to control.

CONCLUSIONS

Increased proliferation in the vaginal polypoid endometriotic tissue may be due to increased local estrogen production. The altered gene expression profile was very similar to the altered gene expression profile seen in peritoneal endometriosis.

Prokineticin 1, homeobox A10, and progesterone receptor messenger ribonucleic acid expression in primary cultures of endometrial stromal cells isolated from endometrium of healthy women and from eutopic endometrium of women with endometriosis

OBJECTIVE

To examine prokineticin 1 (PROK1), homeobox (HOX) A10, and P receptor (PR) messenger ribonucleic acid (mRNA) expression in primary cultures of endometrial stromal cells (ESC) obtained from eutopic endometrial samples of patients with endometriosis and to clarify whether in vitro steroid hormone dependence of PROK1 gene expression is altered in endometriosis.

DESIGN

Prospective laboratory study.

SETTING

Tertiary university hospital.

PATIENT(S)

Twelve normal women (controls) and 12 patients affected by moderate to severe endometriosis in the midsecretory phase of the menstrual cycle.

INTERVENTION(S)

Endometrial specimens were obtained from control women and from women affected by endometriosis; ESC were isolated from endometrial biopsies, and primary cultures were established.

MAIN OUTCOME MEASURE(S)

Real-time polymerase chain reaction analysis of PROK1, HOXA10, and PR mRNA expression in ESC after 1-4 days of steroid hormone treatment and after decidual differentiation.

RESULT(S)

Contrary to ESC from control women, in ESC obtained from women affected by endometriosis PROK1 and PR mRNA expression was not induced by 1-4 days of treatment with steroid hormones. Nevertheless, when ESC from both groups of women were differentiated to decidual phenotype, PROK1 mRNA was up-regulated and PR and HOXA10 mRNA were down-regulated to the same extent.

CONCLUSION(S)

Our results provide additional evidence for P resistance in endometriosis.

Hormonal Repression of miRNA Biosynthesis Through a Nuclear Steroid Hormone Receptor

The maturation of primary microrRNAs (pri-miRNAs) to precursor miRNAs (pre-miRNAs) is mediated by the "microprocessor" complex minimally comprimising two core components, Drosha and DGCR8. However, the roles of RNA-binding proteins associated with these core units in the large Drosha complex remain to be defined. While signal-dependent regulation of miRNA biogenesis is assumed, such regulation remains to be described. here, we provide a short review based on our recent findings of hormonally-regulated pri-miRNA processing by nuclear estrogen receptor.

Attenuated sex steroid receptor expression in fallopian tube of women with ectopic pregnancy

CONTEXT

Sex steroid hormone receptor (SHR) dynamics are well-documented in human endometrium but have not been comprehensively studied in Fallopian tube (FT).

OBJECTIVE

The aim of the study was to compare expression patterns and hormonal regulation of SHR in FT with that described in endometrium and to determine whether SHR expression is altered in FT of women with ectopic pregnancy (EP).

DESIGN

Tissue was analyzed and cultured.

PATIENTS OR OTHER PARTICIPANTS

Women undergoing surgery for benign gynecological conditions (n = 14) and EP (n = 6) participated in the study.

INTERVENTIONS

Quantitative RT-PCR and immunohistochemistry were used to determine SHR mRNA expression and protein localization, respectively. SHR levels were measured in tubal explant cultures stimulated with estrogen and progestogen.

RESULTS

ERalpha and ERbeta mRNAs were constitutively expressed in FT during the menstrual cycle. PR-AB and PR-B mRNAs were decreased in midluteal phase compared to follicular phase. ERalpha, PR-AB, and PR-B mRNAs were down-regulated in human FT in vitro by treatment with progestogen. ERalpha, ERbeta1, ERbeta2, PR, and AR proteins localized to cell nuclei of epithelium, stroma, and smooth muscle of nonpregnant FT. In FT from women with EP, PR-B mRNA was decreased when compared to midluteal FT, and ERalpha protein was not detected.

CONCLUSIONS

SHR expression in FT is different from that observed in endometrium recovered at similar stages of the menstrual cycle, and expression in FT from women with EP is also altered compared with normal FT. These data are an important benchmark for furthering the understanding of normal human FT physiology, changes in expression of SHR in FT in response to progesterone, and disorders of FT function, such as EP.

Implantation-related expression of epidermal growth factor family molecules and their regulation by progesterone in the pregnant rat

The uterine expressions of epidermal growth factor(EGF) family are examined to elucidate their exact role(s) in rat pregnancy. EGF and its receptors' (EGF-R) mRNA levels increased significantly at implantation after which their expression gradually decreased. Heparin-binding EGF (HB-EGF) and transforming growth factor-alpha (TGF-alpha) showed a modest expression at gestation day (GD), GD4 and GD3, respectively, but were much strongly expressed at mid-pregnancy.Amphiregulin (Areg) was strongly expressed around implantation (GD4) and at mid-pregnancy (GD12).Treatment of pregnant rats with RU486 at GD5 or GD8 blocked the expression of all the genes, and administration of immature rats with progesterone (P4) induced the uterine expression of all the genes except HB-EGF. In addition, HB-EGF,TGF-alpha, and Areg proteins in the uterine and glandular epitheliums may participate in mid-pregnancy. Taken together, all of these activities are likely to be controlled by P4 in the uterus of pregnant rats.

Transforming growth factor-beta1 attenuates expression of both the progesterone receptor and Dickkopf in differentiated human endometrial stromal cells

TGFbeta1 is thought to be intimately involved in cyclic tissue remodeling and inflammatory events associated with menstruation. Menstruation is initiated by progesterone withdrawal; however, the underlying mechanisms are not well understood. In the present study, we have tested the hypothesis that locally produced TGFbeta1 may influence expression of progesterone receptor (PR) or the Wnt antagonist Dickkopf-1 (DKK) with consequential impact on regulation of menstruation. Endometrial stromal cells (ESC) were isolated from endometrial biopsy samples collected from patients undergoing gynecological procedures for benign indications. Treatment of differentiated ESC with TGFbeta1 (10 ng/ml) significantly inhibited the expression of mRNAs encoding PR and DKK. TGFbeta1 also attenuated the protein expression of PR and secretion of DKK proteins in culture supernatants. Neutralization of endogenous TGFbeta1 signaling abolished the TGFbeta1-induced effects, significantly increased expression of PR, and increased DKK protein release levels to that of differentiated ESCs, confirming the specificity of the TGFbeta1 effect. Additionally, in vitro decidualization of ESCs significantly augmented DKK protein release. Moreover, although TGFbeta1 was capable of signaling via the Sma- and mothers against decapentaplegic (MAD)-related protein (SMAD) pathway, the inhibitory effect on DKK was SMAD independent. Conversely, the inhibitory effect of TGFbeta1 on PR was dependent on SMAD signal transduction. In conclusion, these results suggest that local TGFbeta1 signaling can potentiate progesterone withdrawal by suppressing expression of PR and may coordinate tissue remodeling associated with menstruation by inducing Wnt-signaling via inhibition of DKK, which we found to be up-regulated as a consequence of decidualization of ESCs.

Transcriptional cross talk between the forkhead transcription factor forkhead box O1A and the progesterone receptor coordinates cell cycle regulation and differentiation in human endometrial stromal cells

Differentiation of human endometrial stromal cells (HESCs) into decidual cells is associated with induction of the forkhead transcription factor forkhead box O1A (FOXO1). We performed a genomic screen to identify decidua-specific genes under FOXO1 control. Primary HESCs were transfected with small interfering RNA targeting FOXO1 or with nontargeting control small interfering RNA before treatment with a cAMP analogue and the progestin, medroxyprogesterone acetate for 72 h. Total RNA was processed for whole genome analysis using high-density oligonucleotide arrays. We identified 3405 significantly regulated genes upon decidualization of HESCs, 507 (15.3%) of which were aberrantly expressed upon FOXO1 knockdown. Among the most up-regulated FOXO1-dependent transcriptional targets were WNT signaling-related genes (WNT4, WNT16 ), the insulin receptor (INSR), differentiation markers (PRL, IGFBP1, and LEFTY2), and the cyclin-dependent kinase inhibitor p57(Kip2) (CDKN1C). Analysis of FOXO1-dependent down-regulated genes uncovered several factors involved in cell cycle regulation, including CCNB1, CCNB2, MCM5, CDC2 and NEK2. Cell viability assay and cell cycle analysis demonstrated that FOXO1 silencing promotes proliferation of differentiating HESCs. Using a glutathione-S-transferase pull-down assay, we confirmed that FOXO1 interacts with progesterone receptor, irrespectively of the presence of ligand. In agreement, knockdown of PR disrupted the regulation of FOXO1 target genes involved in differentiation (IGFBP1, PRL, and WNT4) and cell cycle regulation (CDKN1, CCNB2 and CDC2) in HESCs treated with either cAMP plus medroxyprogesterone acetate or with cAMP alone. Together, the data demonstrate that FOXO1 engages in transcriptional cross talk with progesterone receptor to coordinate cell cycle regulation and differentiation of HESCs.

Pyrethroid insecticides, fenvalerate and permethrin, inhibit progesterone-induced alkaline phosphatase activity in T47D human breast cancer cells

Pyrethroid insecticides exhibited a weak estrogenic activity by stimulation of MCF-7 cell proliferation and induction of alkaline phosphatase (AlkP) enzyme activity in cultured Ishikawa cells. Previously it was reported that fenvalerate and permethrin significantly inhibited the 17beta-estradiol-induced MCF-7 BUS cell proliferation. Although certain pyrethroid insecticides exert estrogenic or antiestrogenic activities, it is not clear whether pyrethroid insecticides act as progesterone agonists or antagonists. Therefore, the aim of this study was to evaluate the effects of fenvalerate and permethrin on AlkP activity as a progesterone-specific response in T47D cells. In the present study, the stimulation of AlkP activity was concentration dependent with addition of progesterone, and maximum activity was observed at concentration of 1 x 10(-8) M. Both fenvalerate (1 x 10(-6) M) and permethrin (1 x 10(-6) M) did not stimulate the AlkP activity, but progesterone (1 x 10(-8) M)-induced AlkP activity was significantly inhibited at 1 x 10(-6) M concentration of fenvalerate and permethrin, respectively. Progesterone receptor (PR) levels in cytosolic protein of T47D cells were studied to determine the relationship between cellular PR expression and AlkP activity. Similar to AlkP activity, progesterone (1 x 10(-8) M) significantly increased PR protein levels compared to control. However, PR protein levels were not affected in T47D cells cultured with fenvalerate and permethrin alone, whereas fenvalerate and permethrin significantly decreased progesterone-induced PR protein levels. Our data indicate that fenvalerate and permethrin exhibit antiprogestagenic activity in T47D human breast cancer cells.

Relationship between sex hormone-binding globulin and pregnancy outcome in women undergoing controlled ovarian hyperstimulation for assisted reproduction

The purpose of this study was to determine whether the changes of sex hormone-binding globulin (SHBG) affect the pregnancy outcome in women undergoing controlled ovarian hyperstimulation (COH) for assisted reproduction. Forty-five infertile women who were undergoing pituitary desensitization and COH for in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) and 19 women with normal menstrual cycles participated in the study. Fasting blood samples of the follicular and luteal phases, including follicular fluid during oocyte retrieval, were obtained for determination of estradiol (E(2)), progesterone (P(4)), testosterone (T), and SHBG concentrations. The SHBG levels increased progressively during the course of COH, but remained constant throughout normal menstrual cycles. A positive correlation existed between E(2) and SHBG levels in both the follicular and luteal phases. The mean plasma SHBG concentration and E(2)/T ratio were significantly higher, while the level of T and the free androgen index were significantly lower, in the luteal phase of women who conceived than in those who did not conceive following COH. The changes of follicular fluid SHBG level and E(2)/T ratio were similar to those in plasma. We concluded, therefore, that increases in SHBG in the follicular and luteal phases may be a reflection of the functional state of ovarian stimulation, and further that such elevations may influence the pregnancy outcome through the modulation of circulating estrogen and androgen balance during down-regulated COH cycles for IVF/ICSI.

Role of FOXO1A in the regulation of insulin-like growth factor-binding protein-1 in human endometrial cells: interaction with progesterone receptor

Insulin-like growth factor-binding protein-1 (IGFBP1) is a major secretory product of the decidualized endometrium. In the present study, we investigated the role of two transcription factors, progesterone receptor (PGR) and a member of the forkhead box class O family of transcription factors (FOXO1A), in the regulation of the IGFBP1 gene in endometrial cells. Human endometrial fibroblasts (HuF) expressed FOXO1A, progesterone receptor A (PGRA), and progesterone receptor B (PGRB) proteins, whereas the endometrial adenocarcinoma cell line, HEC-1B cells, expressed only FOXO1A and no detectable PGR proteins. When FOXO1A expression was silenced using small interference RNA, IGFBP1 expression decreased in both HuF and HEC-1B cells. Using the chromatin immunoprecipitation technique, we demonstrated that liganded PGR was recruited to the IGFBP1 promoter region (-358 to -49). In addition, immunoprecipitation of HuF nuclear proteins with a PGR antibody followed by immunoblotting with anti-FOXO1A revealed that these two proteins interact in these cells. Reporter studies demonstrated that whereas liganded PGRA or PGRB increased a progesterone response element-linked reporter construct, pPRE/ GRE.E1b.Luc, coexpression of FOXO1A inhibited the PGRB response in HuF and synergistically increased PGRA and PGRB response in HEC-1B cells. Furthermore, in HEC-1B cells, FOXO1A increased IGFBP1 promoter activity, and coexpression of PGRA or PGRB further increased the promoter activity in a cooperative manner. In HuF, the response to FOXO1A and PGR was not additive; in fact, it was lower than the sum of the individual responses. Thus, FOXO1A and PGR associate with one another, and each influences the transactivating potential of the other. The cell type-dependent responses strongly implicate the involvement of other cofactors.

Quantitative histomorphometric analysis of gonadal steroid receptor distribution in the normal human endometrium through the menstrual cycle

The aim of this study was to test the hypothesis that the distribution of oestrogen receptor beta (ERbeta) and androgen receptor (AR) are related to cell proliferation or correlated with the expression of progesterone receptor (PR) or oestrogen receptor alpha (ERalpha) in the normal human endometrium. Immunohistochemical distribution of immunoreactive ERbeta in well-characterised menstrual cycle biopsy samples was lowest in proliferative endometrial glands, highest in early secretory phase glands and maintained at approximately 20% throughout the rest of the menstrual cycle and was closely correlated with stromal AR and stromal ERbeta expression. Stromal ERbeta was not significantly altered until the menstrual phase of the cycle and was not correlated with the expression of any other antigen in the stroma or endometrial glands except stromal AR. By contrast, glandular AR immunoreactivity was below 5% early in the cycle, increased during the secretory phase and showed strong expression just before menstruation. PR and Ki-67 expression showed strong positive correlations, indicating that PR may be a potent regulator of endometrial proliferation. These data suggest that glandular ERbeta expression is closely associated with a functional secretory role whereas glandular ERalpha and PR are associated with proliferation; glandular AR expression may be the switch required for menstruation.

Steroid hormones regulate gene expression posttranscriptionally by altering the stabilities of messenger RNAs

Hormones exert powerful effects on reproductive physiology by regulating gene expression. Recent discoveries in hormone action emphasize that regulation of gene expression is not restricted to their alterations of the rate of gene transcription. On the contrary, hormonal effects on the stability of a specific mRNA can profoundly alter its steady-state concentration. The mRNAs encoding hormone receptors are commonly regulated by their own hormones to create autoregulatory feedback loops. Negative and positive autoregulatory feedback loops serve to limit or augment hormonal responses, respectively. After introducing the topics of mRNA degradation and regulated stability, this review focuses on steroid hormone effects on mRNA stabilities. Autoregulation of the mRNAs encoding estrogen, progesterone, androgen, and glucocorticoid receptors by the steroid hormones in reproductive tissues is discussed. In addition, steroid hormone effects on the stabilities of many other mRNAs that are important to reproductive biology are reviewed. These include mRNAs that encode gonadotropin hormones, integrins, growth factors, and inflammatory response proteins. Through these posttranscriptional effects, steroid hormones impact the expression of a large population of genes. Studies of the molecular mechanisms of hormonally regulated mRNA stabilities continue to identify critical mRNA sequence elements and their interactions with proteins. Increased understanding of how hormones affect mRNA stability may yield novel approaches to the therapeutic control of hormone effects, including those essential to reproductive physiology in animals.

Expression and Possible Role of 20.ALPHA.-Hydroxysteroid Dehydrogenase in the Placenta of the Goat

20Alpha-hydroxysteroid dehydrogenase (20alpha-HSD) catalyzes the conversion of progesterone to its inactive form 20alpha-dihydroprogesterone (20alpha-OHP). 20Alpha-HSD is expressed in the murine placenta, suggesting a role, yet unidentified, played by this enzyme during the course of pregnancy. To elucidate the possible roles of 20alpha-HSD during pregnancy, 20alpha-HSD gene expression in the placenta was examined by Northern blot analysis, and progestin (progesterone and 20alpha-OHP) concentrations in the maternal and fetal sera and the amniotic fluid were measured by radioimmunoassay in pregnant Shiba goats. The expression of 20alpha-HSD mRNA was observed in the placenta and the intercaruncular part of the uterus during mid to late pregnancy. Analysis by in situ hybridization revealed that 20alpha-HSD mRNA was mainly localized in the endometrial epithelium of the caruncle side of the placenta. Considerable enzyme activity of 20alpha-HSD was also detected in the cytosolic fraction of the placenta and intercaruncular part of the uterus. Although concentrations of progesterone and 20alpha-OHP in the maternal serum showed similar profiles, progesterone levels in the fetal serum stayed extremely low throughout the pregnancy. The 20alpha-OHP concentration in the fetal serum was always higher than that in the maternal serum. In the amniotic fluid, the concentrations of both progesterone and 20alpha-OHP remained at very low levels throughout the pregnancy. These results support the notion that 20alpha-HSD protects the fetus from the cytotoxic effects of progesterone, and thereby maintains the normal development of the fetus.

Decidualisation of cervical stromal cells

OBJECTIVE

Control of cervical function is poorly understood. The major structural component of the cervix is collagen and peri-partum cervical changes are largely due to the action of collagenase, either released by resident cells or derived from an influx of neutrophils. More importantly, the cell type that initiates the changes in the cervix is unknown although the resident fibroblast is a possible contender. Little is known about the state of the cervical fibroblast during pregnancy. Decidualisation of the endometrium is essential for implantation and pregnancy. In man, pre-decidual and decidual transformation of endometrial stroma occurs under the influence of progesterone. Decidualisation can also be induced in vitro in endometrial fibroblast-like stromal cells where the process is also dependent on elevated intracellular cAMP levels.

STUDY DESIGN

Cultured human cervical fibroblasts were treated with progestin (medroxyprogesterone acetate) and cAMP elevating agents for 6 and 10 days.

RESULTS

After 6 days they expressed and released IGFBP-1 and prolactin (PRL) and underwent morphological changes by 10 days. In addition, there was an increase in progesterone receptor and prostaglandin E type 2 receptor mRNA (but not type 4).

CONCLUSION

The propensity of cervical stromal cells to decidualise suggests that these differentiated cells may be a better model with which to study the initiation of labour.

Oestrogen and progestin responses in human endometrium

Our understanding of the mechanisms of the actions of oestrogens and progestins have evolved from the simple concept of nuclear receptor-mediated regulation of transcription to a highly sophisticated, finely tuned interplay between various coregulators, other signaling cascades and transcription factors. The net result of these complex regulatory mechanisms is a steroid-, cell-, or tissue-specific action of oestrogens and progestins, their antagonists or selective modulators of their receptors. In this review, we have attempted to shed some light on the regulation of the actions of oestrogens and progestins on the human endometrium.

Effect of long-term treatment with steroid hormones or tamoxifen on the progesterone receptor and androgen receptor in the endometrium of ovariectomized cynomolgus macaques

The progesterone receptor (PR) and androgen receptor (AR) belong to the nuclear receptor superfamily. Two isoforms of PR (A and B) have been identified with different functions. The expression of AR, each isoform of PR and their involvement in long-term effects on the endometrium after hormonal replacement therapy (HRT) or tamoxifen (TAM) treatment is not known. The aims of this study were to determine PR(A+B), PRB and AR distribution by immunohistochemistry in the macaque (Macaca fascicularis) endometrium. Ovariectomized (OVX) animals were orally treated continuously for 35 months with either conjugated equine estrogens (CEE); medroxyprogesterone acetate (MPA); the combination of CEE/MPA; or TAM. Treatment with CEE/MPA tended to down-regulate PR in the superficial glands, but increased it in the stroma. TAM treatment increased both the PR and PRB levels in the stroma. Overall, less than 20% of the cells were positive for the PRB isoform and less variation was observed after steroid treatment. AR was found in the stroma, mainly distributed in the basal layer of the endometrium in the OVX and steroid treated groups, but was absent in the TAM treated group. No AR was found in the glandular epithelium. The present data show that long-term hormone treatment affects the PR level, and also the ratio between PRA and PRB in the endometrium.

Messenger RNA for progesterone receptor isoforms in the late-gestation rat uterus

The progesterone receptor (PR) has three isoforms, PR-A, PR-B, and PR-C, which have different physiological effects. PR-A may inhibit PR-B-mediated transcription. Parturition requires withdrawal of progesterone (P4). This could occur through decreased P4 concentrations and/or a change in PR isoforms to diminish the effect of P4. We measured mRNA for PR isoforms in rat uterine tissues through late gestation and investigated the effects of antagonists to estrogen (tamoxifen) and P4 (RU-486). Two specific probes were used for ribonuclease protection assays; one (PR-total) measured PR-A, PR-B, and PR-C, and the other recognized only PR-B. PR-total mRNA increased significantly through late gestation, whereas PR-B was unchanged. The ratio of PR-total to PR-B peaked on the day before parturition. Tamoxifen delayed parturition and inhibited the increase in PR-total without affecting PR-B mRNA. RU-486 caused early parturition associated with increased PR-total mRNA, with no change in PR-B. We conclude that there are significant changes in PR isoforms in late-gestation rat uterus. These changes may be regulated by estrogen and P4 and may influence the timing of parturition.

Endometrial hormone receptors and proliferation index in the periovulatory phase of stimulated embryo transfer cycles in comparison with natural cycles and relation to clinical pregnancy outcome

OBJECTIVE

To investigate the endometrial steroid receptors and proliferation index in GnRH analogue/hMG-stimulated cycles in comparison with natural cycles and their relation to clinical pregnancy outcome.

DESIGN

Prospective observational study.

SETTING

Tertiary referral center.

PATIENT(S)

Twenty-seven stimulated patients with GnRH agonist and hMG. Twenty normo-ovulatory patients were the natural cycle controls.

INTERVENTION(S)

Endometrial aspiration biopsies: in stimulated cycles on the day of oocyte retrieval within the ET cycle (Day OPU) (n = 20) or 2 days later (Day OPU + 2) (n = 7); in natural cycles on the natural day of ovulation (Day NO) (n = 10) or on the day of ovulation + 2 (Day NO + 2) (n = 10).

MAIN OUTCOME MEASURE(S)

Comparison of endometrial maturation, estrogen (ER) and P receptor (PR), and proliferation index by immunohistochemistry in natural and stimulated cycles, correlation with pregnancy outcome in stimulated cycles.

RESULT(S)

Stimulated cycles Day OPU showed significantly advanced endometrial maturation compared to natural cycles Day NO; stromal ER and glandular and stromal PR staining was lower in stimulated than in natural cycles, but higher on Day OPU than on Day NO + 2; proliferation index was lower in all stimulated cycles. Steroid receptors and proliferation index in stimulated cycles were unrelated to clinical pregnancy occurrence.

CONCLUSION(S)

Compared to natural cycles, ovarian stimulation induced an imbalance in endometrial ER and PR and led to a profound antimitotic effect in the peri-ovulatory phase. These parameters were, however, not predictive of clinical pregnancy in cycles with ET.

Progesterone receptor activates its promoter activity in human endometrial stromal cells

Previous studies have shown that progestin increases the content of progesterone receptor (hPRA and hPRB) and the hPR mRNA during decidualization of human endometrial stromal cells suggesting that endogenous hPR enhances the transcription of the hPR gene. In the present study, we provide evidence that hPR regulates the promoter activity mediated through an active Sp1 site. In stromal cells treated with medroxyprogesterone acetate, the promoter activity was significantly increased when cells were co-transfected with hPR expression vector. Progressive deletion analysis showed that the highest activity was derived from the promoter region between -55 and +31 bp. Transactivation by hPR was dose dependent. The capacity of hPRA was stronger than that of hPRB. The ligand binding domain, but not DNA binding domain of the hPR was required for the transactivation. The proximal promoter region lacks a canonical progesterone response element. Instead, an active Sp1 site (-49 to -43 bp) has been confirmed. Mutation of the Sp1 site eliminated the effect of hPR activation. The promoter activity was increased by over expression of Sp1, whereas Sp3 had no effect. Electrophoretic mobility shift assay showed that the promoter region between -55 and +31 bp bound to Sp1 family proteins, Sp1 (C2 complex) and Sp3 (C1 and C3 complexes) identified by antibodies to Sp1 and Sp3. Sp1 complex formed by extracts of stromal cells was less intense than that formed by progestin-decidualized stromal cells. Sp1/DNA binding was enhanced when stromal cell extracts were incubated with calf intestine alkaline phosphatase (CIP) suggesting that dephosphorylation of Sp1 enhances the DNA binding. Addition of protein kinase inhibitor, H-89 or H-7, enhanced the hPR stimulated promoter activity. Western blot analysis showed that endometrial stromal/decidual cell extracts contained a wide band of Sp1 spanning from approximately 105 to 96 kDa and was resolved into one band at 96 kDa by CIP. Decidual cell extracts are abundant with the 96 kDa Sp1. In addition, the 96 kDa Sp1 was co-precipitated with ligand-activated hPRA or hPRB in the decidual cell nuclear extracts. These data suggest that dephosphorylated Sp1, abundant in decidual cells, enhances the binding to both DNA and hPR resulting in a robust increase of the hPR promoter activity.

Ligand activated hPR modulates the glycodelin promoter activity through the Sp1 sites in human endometrial adenocarcinoma cells

Human endometrium produces glycodelin-A (GdA). The GdA mRNA is highly expressed in progestin-sensitized human endometrial glandular epithelial cells. The mechanism of GdA gene expression, however, is not clear. To understand the cell specific GdA gene transcription, our first approach was to identify the cis-element in the GdA promoter using transfection assay in a human endometrial adenocarcinoma cell line (HEC-1B, a cell line originally derived from the glandular component of the endometrium). The GdA promoter (-1900 to +20 bp) was linked to the luciferase reporter gene to construct p1900Luc, along with two shorter promoter constructs, p1100Luc and p304Luc. Deletion analysis showed that the basal promoter activity was derived from the region between -304 to +20 bp. This region contains three putative Sp1 binding sites (Sp1-1, -243 to -238 bp; Sp1-2, -207 to -202 bp; and Sp1-3, -56 to -49 bp). Mutation analysis at the Sp1 sites showed that p304Spm2Luc and p304Spm3Luc reduced the activity by 80%, while p304Spm1-2-3Luc reduced the activity by 95%. Sp1-1 mutation, however, had no effect. These results showed that two of the three Sp1 cis-elements mediate the basal promoter activity of the GdA gene. Electrophoretic gel mobility shift showed that at least two specific binding proteins in the nuclear extracts of HEC-1B cells bound to the oligo containing Sp1-2 or Sp1-3 cis-element. Sp1 antibody reduced the specific binding complex by 70% suggesting that Sp1 transcription factor regulates GdA gene expression. In addition, over expression of Sp1 increased the promoter activity. To determine whether progestin would modulate the promoter activity, HEC-1B cells were transfected with p304Luc and with progesterone receptor (either hPR-A or hPR-B) expression vector. Medroxyprogesterone acetate increased the promoter activity (3-fold) derived from p304Luc but not from the mutant, p304Spm1-2-3Luc. In contrast, the promoter activity was slightly reduced in cells treated with estradiol and co-transfected with estrogen receptor expression vector. These data indicate that ligand-activated PR stimulates GdA gene expression mediated through the functional Sp1 sites.

Immunolocalization of progesterone receptors in bovine placentomes throughout mid and late gestation and at parturition

The corpus luteum is the main source of progesterone (P(4)) responsible for maintenance of gestation in cattle. So far it has not been possible to assign any biological role to placental P(4), which contributes only marginally and temporarily to peripheral maternal blood levels. In order to identify possible P(4) target cells within the placenta, placentomes from 150-, 220-, 240-, and 270-day-pregnant cows and from parturient cows (3 animals per group) were screened immunohistochemically for expression of the progesterone receptor (PR). During gestation, PR-positive staining was found exclusively in the nuclei of caruncular stromal cells (CSC; maternal part of the placentome) and of caruncular vascular pericytes. In placentomes from parturient cows, occasional positive nuclear staining was also observed in the walls of small caruncular arteries. The percentage of PR-positive CSC increased slightly from 51.8 +/- 2.6% on Day 150 to 56.2 +/- 5.6% at Day 270 (p < 0.05) and was 58.9 +/- 1.8% at parturition. These results suggest that in pregnant cattle, CSC are under the control of P(4) of placental rather than luteal origin. Thus, whereas luteal P(4) may regulate "coarse" systemic progestational functions in the maternal compartment in the classical hormonal manner, placental P(4) may act as a paracrine factor involved in the local regulation of caruncular growth, differentiation, and functions.

Activation of the insulin-like growth factor binding protein-1 promoter by progesterone receptor in decidualized human endometrial stromal cells

Insulin-like growth factor binding protein-1 (IGFBP-1) is induced extensively when human endometrial stromal cells are decidualized by progestin and relaxin in a long-term primary culture system. The purpose of this study is to investigate whether progesterone receptor (PR) directly activates the IGFBP-1 gene promoter. In decidualized stromal cells, activity of the IGFBP-1 promoter (from -1.2 kb to +68 bp) containing putative progesterone-response elements (PREs) was increased 80-fold. Mutation of either 5' or 3' half-site of the putative PRE1 site (from -193 to -179 bp) reduced the promoter activity. Mutations that converted PRE1 closer to consensus PRE increased the promoter activity. In undifferentiated stromal cells, mutations of PRE sites had no effect on the promoter activity. When a PR expression vector (hPR1) was cotransfected, progestin increased promoter activity derived from p275CAT but not from p1.2CAT, suggesting that the function of PRE1 was repressed by the region from -1.2 kb to -275 bp in the promoter. Progestin did not increase promoter activity derived from p275CAT without cotransfection of hPR1, suggesting that endogenous PR alone is insufficient to activate PRE1. In summary, results indicate that the PRE1 site of the IGFBP-1 promoter mediates a direct activation of PR on transcription specifically in decidualized stromal cells.

Hormonal treatment of endometrial cancer

This article summarizes the endocrine background of women with endometrial cancer at both peripheral and tissue levels, and the current status of clinical trials of hormonal, cytotoxic, and combination regimens. Because significant advances in systemic therapy are required to improve the prognosis of endometrial cancer, recommendations for future clinical investigations will be based on these recent biologic observations.

Progesterone and estrogen regulation of rat decidual cell expression of proliferating cell nuclear antigen

This study was an examination of the role of progesterone (P4) and estradiol-17beta (E2) as stromal cell mitogens in the decidua basalis (DB) of the rat during pregnancy. Pregnant rats were ovariectomized (Ovx) on Days 8 and 12 of pregnancy, treated with P4, E2, or both, and killed on Days 10 and 14, which correspond to times of stromal cell proliferation and regression, respectively. In some experiments, rats received pellets of the anti-progestin RU-486 on Day 9 and were killed 6, 12, and 24 h later. The mitotic index (MI) and in situ image analysis of expression of proliferating cell nuclear antigen (PCNA) were used to assess cell cycle progression. Highest expression of PCNA occurred on Days 8-12 of pregnancy, and MI was maximum; MI became zero and PCNA expression decreased dramatically thereafter (i.e., Days 14, 17, 21). Percentage of cells expressing intense PCNA on Day 10 (40%) declined to 5% after Ovx and Ovx + E2 (p < 0.05), whereas Ovx + P4 maintained PCNA. By Day 14, only 1% of stromal cells expressed intense PCNA, which was not significantly altered by Ovx, Ovx + E2, or Ovx + P4 but increased after Ovx + P4 and E2 (p < 0.05). By 6 h of RU-486, MI declined 3-fold, and intense PCNA expression was essentially lost. These changes preceded loss of histological integrity of the DB. Cells with undetectable PCNA steadily increased from 8% at 6 h to 28% by 24 h (p < 0.05). Thus RU-486 appeared to block cell cycle progression and enhanced PCNA turnover. P4 was essential for stromal cell proliferation during early pregnancy (Days 8-10), but this action was lost by Day 14.