Nuclear Progesterone Receptor Research Articles

Vaginal leiomyoma in a goat expressing the nuclear progesterone receptor (PGR): a case report

BackgroundThe risk of developing tumorous diseases in the genital tract also increases with age in animals. One of the classified tumor types is genital leiomyoma. Presently, our understanding of the pathogenesis of this tumor in goats is, however, limited. This accounts also for the information regarding the presence of steroid hormone receptors and, thus, possible responsiveness to circulating steroids.Case presentationThis study describes the case of a vaginal tumor in a seven-year-old Anglo-Nubian goat. The goat was presented due to blood mixed vaginal discharge. Per vaginal examination a singular pedunculated mass in the dorsum of the vagina measuring approximately 3 cm x 4 cm x 4 cm was revealed. After administering epidural anesthesia, the mass was removed electrothermally. There were no postoperative complications. The histopathological examination identified the mass as a leiomyoma. The immunohistochemical examination revealed the presence of the nuclear progesterone receptor (PGR) in the tumor tissue. One year after the surgery, during the follow-up examination, the goat was in good overall health, and the owners had not observed any recurrence of vaginal discharge.ConclusionsWhen observing vaginal discharge in goats, it is important to consider the possibility of genital tract tumors. These tumors may express sex steroid receptors. In the future, it is worth considering the investigation of potential approaches for preventing tumorigenesis or treating the tumor, such as castration or the administration of antiprogestogens.

Black rockfish（Sebastes schlegelii）nuclear progesterone receptor: Cloning, tissue distribution and potential role in ovoviviparity teleost pregnancy and parturition

Nuclear progesterone receptor (nPR) is a member of the nuclear receptor family known to play a critical role in gonad development, gametogenesis, and ovulation in vertebrates, and also important in pregnancy maintenance and parturition in mammals. However, its biological functions in ovoviviparity teleosts are less clear. This study aimed to determine the possible role of nPR in fish oogenesis, pregnancy and parturition using black rockfish as a model. The npr, which consists of 2076 bp and codes for a 691 amino acids protein, was cloned. Phylogenetic analysis revealed that the nPR of black rockfish is more conserved in teleosts. Quantitative real-time PCR analyses in various tissues showed that npr was mainly detected in the pituitary followed by the ovary, testis and brain, while it was very low or undetectable in the spleen, head kidney, intestine and gill. During the gonadal development process, the npr level showed no variation in the ovary. In testis, the mRNA level of npr showed varied expression in different developmental stages with the highest level in the maturation stage. Detection of npr expression during fertilization and the perinatal period further showed that nPR may play important roles in the regulation of pregnancy and the parturition. In situ hybridization further revealed that npr mRNA was observed in the follicular cell layer during the perinatal period. The results from in vitro experiments showed that npr level was significantly downregulated when the primary cultured follicular cells during vitellogenesis (stage Ⅳ) were exposed to hCG. Studies using primary culture of black rockfish ovarian cells during the perinatal period, treated in vitro revealed that genes related to PGs synthesis (pla2g4a, cox2) and matrix metalloproteinases (mmp2, mmp9) were upregulated in response to 17,20β-P. However, treatment with 17,20β-P downregulated npr expression. In conclusion, these data suggest that nPR plays an essential role in fertilization, pregnancy maintenance and parturition in black rockfish.

Establishment of a graphene quantum dot (GQD) based steroid binding assay for the nuclear progesterone receptor (pgr)

Previously, we established a homogeneous assay for membrane progesterone receptor alpha (mPRα) ligands by conjugating semiconductor nanoparticles known as graphene quantum dots (GQDs) to mPRα. When mixed with a progesterone-BSA-fluorescein isothiocyanate conjugate (P4-BSA-FITC), fluorescence occurred by fluorescence resonance energy transfer (FRET) but was reduced by the ligand-receptor binding activity. The established way showed ligand specificity as mPRα protein. In this study, we tried to establish the same way for nuclear progesterone receptor (Pgr). The ligand-binding domain (LBD) of zebrafish Pgr (zPgrLBD) was expressed as a fusion protein with glutathione S-transferase (GST) (GST-zPgrLBD). The recombinant protein was then purified and coupled with GQDs to produce GQD-conjugated GST-zPgrLBD (GQD-GST-zPgrLBD). When mixed with a P4-BSA-FITC and activated by 370 nm light, fluorescence at 520 nm appeared by FRET mechanism. Fluorescence at 520 nm was reduced by adding free progesterone to the reaction mixture. Reduction of fluorescence was induced by zPgr ligands but not by steroids or chemicals that do not interact with zPgr. The results showed the formation of a complex of GQD-GST-zPgrLBD and P4-BSA-FITC with ligand-receptor binding. The binding of the compounds was further confirmed by a radiolabeled steroid binding assay. A homogenous ligand-binding assay for nuclear progesterone receptor has been established.

Abstract 6877: Progesterone promotes immunosuppression in the murine mammary gland by causing T cell death

Abstract Breast Cancer is the most common cancer diagnosed in women in the United States. Second only to lung cancer, breast cancer results in the greatest number of cancer deaths for women. Hormone receptor positive (HR+) breast cancers - cancers expressing the nuclear receptors for steroid hormones estrogen and progesterone, termed the estrogen receptor (ER) and progesterone receptor (PR) - make up the largest proportion of diagnosed breast cancers by a significant margin. So, although the HR+ subtype is less aggressive compared to others, it continues to be the largest contributor to breast cancer mortality. Treatment consists of anti-endocrine therapies, largely targeting ER/estrogen, the established drivers of breast cancer growth. Most women respond well to these therapies, but for women who do not, there are few alternative options. With the advent of immunotherapy and its successes in treating and controlling certain tumor types, many were hopeful that it could be employed for breast cancer as well. However, breast cancers, especially HR+ breast cancers, are considered “immune cold.” They lack high proportions of tumor-infiltrating lymphocytes (TILs), have low neoantigen production, and high percentages of immunosuppressive cells. A contributing factor could be the hormones present in the tumor microenvironment. The accepted paradigm is that lifetime exposure to estrogens drives the development of HR+ breast cancer, but both estrogen and progesterone are part of the normal menstrual cycle. Prior work from our lab has uncovered a novel immune-modulatory role for progesterone, pivotal to promoting the growth of PR-positive mammary tumors. Recent preliminary data from our lab show that progesterone treatment conveys immune protection against T cell killing in a co-culture with E0771 mammary gland tumor cells. However, when activated in monoculture, T cells exposed to increasing concentrations of progesterone have no differing expression of cell surface activation or exhaustion markers, implying that progesterone is not eliciting this effect by interfering with the T cell activation cascade nor is it inducing premature exhaustion. Interestingly, progesterone treatment instead leads to a concentration-dependent increase in T cell death compared to the untreated control. In vivo, these results are supported as progesterone treatment decreases the amount of total CD3+ T cells, and specifically the cytotoxic CD8+ subset, in the mammary glands of mice. These results suggest that progesterone could modulate the breast and tumor microenvironment, providing tumor cells with protection from immunosurveillance and contributing to HR+ breast cancer development. These data also argue for the use of anti-progestins to be added to the HR+ breast cancer treatment regimen to boost anti-tumor immune activity. Citation Format: Amanda Heard, Lauryn R. Werner, Eilidh I. Chowanec, Harmony Saunders, Julio Tinoco, Zachary C. Hartman, Christy R. Hagan. Progesterone promotes immunosuppression in the murine mammary gland by causing T cell death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6877.

Abstract 3587: Evidence that membrane progesterone receptors (mPR) play a key role in cancer metastases in most cases of metastatic cancer

Abstract An immunomodulatory protein called the progesterone induced blocking factor (PIBF) is essential for the fetal semi-allograft to escape immune surveillance. Many cancer cell lines make both mPRs for PIBF and the protein itself. The progesterone receptor (PR) antagonist mifepristone added to cancer cell line cultures down-regulated mRNA for PIBF and the PIBF protein. This IRB approved study (that required a compassionate use IND from the FDA) evaluated oral mifepristone 200mg per day (majority) or 300mg in patients with very advanced cancers with no more treatment options available. Patients would remain under the care of their primary oncologists (FDA requirement). Because the nuclear (n) PR may be protective against cancer spread, only patients with cancers negative for the nPR were treated. Patients with the following types of cancers received mifepristone: non-small cell lung cancer (NSCLC) (n=9), small cell lung cancer (SCLC) (n=2), colon (n=3), pancreatic (n=2), thymic epithelial cell (n=1), transitional cell carcinoma of the renal pelvis (n=1), malignant fibrous histiocytoma (n=1), glioblastoma multiforme stage IV (n=1), leiomyosarcoma (n=1). All 21 patients showed significant palliative benefits, especially but not limited to, marked reduction in pain and marked improvement in energy, decreased dyspnea on exertion, and return of mental clarity. For those who had repeat CT evaluation no one failed to show shrinkage and decrease in malignant lesions and 2 (leiomyosarcoma and SCLC) showed complete remission after a few months on mifepristone. Five patients (3 females, 2 males) with SCLC (1), NSCL (n=3) and fibrous osteosarcoma (n=1) survived at least 5 years with 2 dying from cancer unrelated causes (SCLC and NSCLC). Two are still alive (NSCLC with EGFR mutation and brain metastases). The male with fibrous osteosarcoma died after stopping mifepristone in favor of a new drug recommended by his oncologist. Two patients lived over 2 years. Most would have lived longer had they not stopped mifepristone. Other observations: significant palliative benefits are seen within 3 weeks of taking mifepristone before any evidence of significant tumor regression. After a period of time, some lesions (especially in the primary location) may start growing slowly, but this is not a sign of loss of drug efficacy and long good quality life is still probable if one remains on the drug. The cancer spreads rapidly if one stops the mifepristone. The usual reason for stopping the drug was intervention by the primary oncologist suggesting a new clinical trial because there has not been complete remission of the cancer or some tumor growth (usually slow) or finances. Not one patient had a side effect. Hopefully this study will generate interest in treating patients with advanced cancer with mifepristone, especially those devoid of the nPR. These data support the role of mPRs in cancer proliferation. Citation Format: Jerome H. Check, Diane Check, Brooke Neumann, Carrie Wilson. Evidence that membrane progesterone receptors (mPR) play a key role in cancer metastases in most cases of metastatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3587.

Abstract PR003: The combination of the glucagon like peptide-1 receptor agonist semaglutide and the progestin levonorgestrel is highly effective in preclinical studies of endometrial cancer

Abstract Obesity is a major risk factor for endometrial cancer (EC), and glucagon like peptide-1 receptor (GLP-1R) agonists such as semaglutide may be helpful to achieve weight loss during conservative treatment or for EC prevention. Progestins such as levonorgestrel are effective in preventing or treating early-stage EC. However, better and more durable response rates could be achieved using combinatorial therapeutic regimens of well tolerated agents with the potential to enhance progestin effectiveness. We theorized that the combination of semaglutide and levonorgestrel would be useful as a novel treatment or prevention regimen and tested this hypothesis using EC cell lines, patient-derived organoids, and RNA-sequencing from patient samples. From the molecular perspective, EC cell lines, organoids, and tissues express GLP-1R as determined by both qPCR and Western blotting, and GLP-1R agonist treatment induces GLP-1R mRNA transcription through positive feedback mechanisms in EC cell models. Preclinical studies in 6 patient-derived organoid models of EC demonstrated the promising therapeutic effects of the combination of semaglutide and levonorgestrel on endometrial cell viability. Specifically, patient-derived organoids from grade 1 endometrial carcinomas were treated with progesterone, levonorgestrel, semaglutide, or levonorgestrel + semaglutide at drug concentrations of 100 nM for 72 hours. Multiple models demonstrated a significant reduction in viability in response to combinatorial treatment. Most interesting was the induction of not only the membrane GLP-1 receptor with treatment, but also the significant upregulation of nuclear and membrane progesterone receptors, PR and PGRMC1/2, respectively, indicating a positive feedback loop between semaglutide and progestins such as levonorgestrel. In addition, other steroid hormone receptor mRNAs such as the estrogen, androgen and mineralocorticoid receptors (ER, AR, and MR) were similarly upregulated. In these studies, we identify synergistic molecular crosstalk between the GLP-1R and steroid hormone receptor pathways with the potential to enhance the anti-cancer activity of semaglutide and levonorgestrel when combined. Future studies are aimed at testing this regimen in patients conservatively managed for atypical endometrial hyperplasia or low-grade endometrial cancers. Citation Format: Kimberly K. Leslie, Andrea Hagemann, Kristina Thiel, Ian Hagemann, David Mutch, Eric Devor, Paige Malmrose. The combination of the glucagon like peptide-1 receptor agonist semaglutide and the progestin levonorgestrel is highly effective in preclinical studies of endometrial cancer [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr PR003.

767 Differential Packaging of Nuclear and Membrane Progesterone Receptors in Myometrial and Decidual Cell Exosomes

767 Differential Packaging of Nuclear and Membrane Progesterone Receptors in Myometrial and Decidual Cell Exosomes

Applying a novel kinomics approach to study decidualization and the effects of antigestagens using a canine model†.

Maternal decidual cells are crucial for the maintenance of canine pregnancy as they are the only cells expressing the nuclear progesterone (P4) receptor (PGR) in the placenta. Interfering with P4/PGR signaling adversely affects decidual cells and terminates pregnancy. Although immortalized dog uterine stromal (DUS) cells can be decidualized in vitro using cAMP, the involvement of cAMP-dependent kinases in canine decidualization had not been investigated. Therefore, the present project investigated changes in the kinome of DUS cells following in vitro decidualization, using the serine/threonine kinase (STK) PamChip assay (PamGene). Decidualization led to a predicted activation of 85 STKs in DUS cells, including protein kinase (PK) A, PKC, extracellular signal-regulated kinase (ERK)1/2 and other mitogen-activated protein kinases (MAPKs), calcium/calmodulin-dependent protein kinases (CAMKs), and Akt1/2. In addition, blocking PGR with type 2 antigestagens (aglepristone or mifepristone) decreased the activity of virtually all kinases modulated by decidualization. The underlying transcriptional effects were inferred from comparison with available transcriptomic data on antigestagen-mediated effects in DUS cells. In targeted studies, interfering with PKA or MAPK kinase (MEK)1/2 resulted in downregulation of important decidualization markers (e.g., insulin-like growth factor 1 (IGF1), prostaglandin E2 synthase (PTGES), prolactin receptor (PRLR), PGR, and prostaglandin-endoperoxide synthase 2 (PTGS2/COX2)). Conversely, blocking of PKC decreased the mRNA availability of IGF1, PGR, and PTGS2, but not of PTGES and PRLR. Moreover, suppressing PKA decreased the phosphorylation of the transcription factors cJUN and CREB, whereas blocking of PKC affected only cJUN. This first kinomics analysis to target decidualization showed an increased activity of a wide range of STKs, which could be hindered by disrupting P4/PGR signaling. Decidualization appears to be regulated in a kinase-dependent manner, with PKA and PKC evoking different effects.

195 Nuclear progesterone receptor and mitochondria profiling during bovine oocyte growth

195 Nuclear progesterone receptor and mitochondria profiling during bovine oocyte growth

The role of non-genomic actions of progesterone and its membrane receptor agonist in ovarian cancer cell death.

Progesterone therapy is a relatively inexpensive treatment option for endometrial and breast cancers, with few side effects. Two signaling pathways usually mediate the physiological effects of progesterone, namely genomic and non-genomic actions. Genomic action occurs slowly via the nuclear progesterone receptor (PR), whereas the membrane progesterone receptor (mPR) induces rapid non-genomic action. We investigated the effects of progesterone and various PR agonists on ovarian cancer cells. PR expression of six serous ovarian cancer cell lines was examined by western blotting, and mPR expression was examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). PR-negative and mPR-positive ovarian cancer cells were exposed to progesterone and seven types of PR agonists (medroxyprogesterone acetate [MPA], dehydroepiandrosterone, dienogest, levonorgestrel, drospirenone, pregnenolone, and allopregnanolone) at 10-400 μM, and viable cell counts after exposure for 30 min were measured using the water-soluble tetrazolium (WST-1) assay. Ovarian cancer cell lines were exposed to 100 μM progesterone, and the expression of BAX, a pro-apoptotic protein, after 1-5 min was examined by western blotting. Western blotting detected no PR expression in the six serous ovarian cancer cell lines. In contrast, RT-qPCR detected mPR expression in all six serous ovarian cancer cell lines. Progesterone and MPA-induced cell death in all tested ovarian cancer cell lines in a concentration-dependent manner, whereas no effect was observed for other PR agonists. Western blotting revealed that pro-apoptotic protein BAX expression occurred 1 min after exposure to progesterone, suggesting that the cytocidal effects are mediated by rapid non-genomic action. Progesterone and MPA exhibited a rapid cytocidal effect on PR-negative ovarian cancer cells through non-genomic action. Progesterone and MPA could be novel adjuvant therapies for ovarian cancer.

Navigating a plethora of progesterone receptors: Comments on the safety/risk of progesterone supplementation in women with a history of breast cancer or at high-risk for developing breast cancer

Progesterone and progestin agonists are potent steroid hormones. There are at least three major types of progesterone receptor (PR) families that interact with and respond to progesterone or progestin ligands. These receptors include ligand-activated transcription factor isoforms (PR-A and PR-B) encoded by the PGR gene, often termed classical or nuclear progesterone receptor (nPR), membrane-spanning progesterone receptor membrane component proteins known as PGRMC1/2, and a large family of progestin/adipoQreceptors or PAQRs (also called membrane PRs or mPRs). Cross-talk between mPRs and nPRs has also been reported. The complexity of progesterone actions via a plethora of diverse receptors warrants careful consideration of the clinical applications of progesterone, which primarily include birth control formulations in young women and hormone replacement therapy following menopause. Herein, we focus on the benefits and risk of progesterone/progestin supplementation. We conclude that progesterone-only supplementation is considered safe for most reproductive-age women. However, women who currently have ER + breast cancer or have had such cancer in the past should not take sex hormones, including progesterone. Women at high-risk for developing breast or ovarian cancer, either due to their family history or known genetic factors (such as BRCA1/2 mutation) or hormonal conditions, should avoid exogenous sex hormones and proceed with caution when considering using natural hormones to mitigate menopausal symptoms and/or improve quality of life after menopause. These individuals are urged to consult with a qualified OB-GYN physician to thoroughly assess the risks and benefits of sex hormone supplementation. As new insights into the homeostatic roles and specificity of highly integrated rapid signaling and nPR actions are revealed, we are hopeful that the benefits of using progesterone use may be fully realized without an increased risk of women’s cancer.

New Insights on the Progesterone (P4) and PGRMC1/NENF Complex Interactions in Colorectal Cancer Progression.

The literature data regarding the risk of colorectal cancer (CRC) in the context of hormone therapy (HT), including both estrogen-progestogen combinations and estrogen alone, are inconclusive. The precise relationship underlying the action of progesterone (P4) and progesterone receptors in CRC has yet to be determined. We characterized the expression profiles of both nuclear and membrane progesterone receptors and their potential cofactors in CRC tissues. Additionally, we analyzed the P4 and NENF treatment effects on the cell proliferation and invasion of DLD-1 and HT-29 colorectal cancer cells. We observed a weak expression of the nuclear P4 receptor (PGR), but an abundant expression of the P4 receptor membrane component 1 (PGRMC1) and neuron-derived neurotrophic factor (NENF) in the CRC tissues. P4 treatment stimulated the proliferation of the DLD-1 and HT-29 CRC cells. The co-treatment of P4 and NENF significantly increased the invasiveness of the DLD-1 and HT-29 cells. A functional analysis revealed that these effects were dependent on PGRMC1. AN immunocytochemical analysis demonstrated a cytoplasmic co-localization of PGRMC1 and NENF in the CRC cells. Moreover, the concentration of serum NENF was significantly higher in CRC patients, and P4 treatment significantly increased the release of NENF in the DLD-1 cells. P4 or NENF treatment also significantly increased the IL-8 release in the DLD-1 cells. Our data may provide novel insights into the action of P4 and PGRMC1/NENF in CRC progression, where NENF may act as a potential PGRMC1 co-activator in non-classical P4 signaling. Furthermore, NENF, as a secreted protein, potentially could serve as a promising circulating biomarker candidate for distinguishing between colorectal cancer patients and healthy individuals, although large-scale extensive studies are needed to establish this.

SAT001 Membrane Progesterone Receptors Induce Glycogenolysis In Uterine Epithelial Cells

Abstract Disclosure: M. Berg: None. M. Dean: None. In humans and cattle, 40-60% of pregnancies fail, with most losses occurring prior to or during implantation. Throughout this time, the developing embryo needs glucose to survive. The demand for glucose increases dramatically at the morula stage as the embryo enters the uterus. Yet, how glucose is regulated to match the changing needs of the embryo is unclear. Glycogen is composed of thousands of glucose molecules and is present in the uterine epithelium of many species. Our lab has shown that the glycogen content of the bovine uterine epithelium was lower during the luteal phase than at estrus. Therefore, our objective was to elucidate the role of progesterone in glycogenolysis of uterine epithelial cells. Bovine uterine epithelial (BUTE) cells were treated with insulin-like growth factor 1 (IGF1) to stimulate glycogenesis, followed by treatment for 48 hours. Progesterone decreased glycogen levels in BUTE cells by 99% (P=0.0002). RU486 did not block progesterone's effect, indicating that the effect of progesterone was not mediated by nuclear progesterone receptors (nPR). Thus, we hypothesized that the effect of progesterone is mediated by membrane progesterone receptors (mPRs). RT-PCR confirmed that BUTE cells expressed all five mPRs (α, β, γ, δ, and ε). Like progesterone, a specific mPR agonist (Org OD 02-0) decreased glycogen levels in BUTE cells by 99% (P<0.0001). Indicating a potential for mPRs to regulate glycogen in vivo, immunohistochemistry showed that the bovine uterine epithelium expressed high levels of mPRα. These results validate that progesterone is acting through mPRs to stimulate glycogen breakdown in BUTE cells. Once progesterone binds to the mPR, two signaling pathways can be activated, cAMP and AMPK. Neither progesterone nor Org OD 02-0 changed intracellular cAMP concentrations. In agreement, the adenylyl cyclase activator forskolin increased cAMP concentration but did not decrease glycogen. BUTE cells treated with progesterone had increased pAMPK levels at 24 hours compared to the control (P=0.0001). BUTE cells treated with an AMPK activator (D942) had a decrease in glycogen (P=0.0051). Supporting these results in vivo, pAMPK levels in the uterine epithelium were high in the bovine uterine epithelium during the luteal phase when glycogen levels were low. In a human model, progesterone and Org OD 02-0 decreased glycogen levels to a similar extent in Ishikawa cells that express mPRs but not nPRs (P=0.0027). In conclusion, progesterone acting through the mPR and AMPK to stimulate glycogenolysis may play a crucial role in providing glucose to endometrial tissue or the growing embryo. Presentation: Saturday, June 17, 2023

Effects of mifepristone, a model compound with anti-progestogenic activity, on the development of African clawed frog (Xenopus laevis)

The objective of this study was to assess the effects of a model substance with anti-progestogenic activity on development of African clawed frog (Xenopus laevis) from tadpole to juvenile stage. Mifepristone, a synthetic progesterone receptor-blocking steroid hormone used in medicine as an abortifacient, was chosen as a model compound with anti-progestogenic activity. In the experiment, African clawed frog tadpoles were exposed to mifepristone at three concentrations (2, 21, and 215 ng L−1). A control group was exposed to dimethyl sulfoxide (DMSO; 0.001 %). The experiment started when tadpoles reached stages 47–48 according to Nieuwkoop and Faber (NF; 1994) and continued until stage NF 66, when metamorphosis was complete. Exposure to mifepristone had no significant effect on the rate of tadpole development, occurrence of morphological anomalies, weight, body length, or sex ratio. Mortality was within an acceptable range of 0–3.6 % throughout the test and did not differ among the groups. Histopathological examination of the gonads and thyroid gland revealed no significant changes. Therefore, we can conclude that mifepristone had no negative effect on development of the African clawed frog up to juvenile stage. Nevertheless, at the highest tested mifepristone concentration (215 ng L−1), gene expression analysis revealed up-regulation of mRNA expression of nuclear progesterone receptor (npr), membrane progesterone receptor (mpr), estrogen receptor beta (esrβ), and luteinizing hormone (lh) in the brain–pituitary complex of exposed frogs at stage NF 66. Higher mRNA expression of npr was also found in frogs exposed to 22 ng L−1 mifepristone compared to the solvent control. These findings confirmed the anti-progestogenic activity of mifepristone in frogs because the up-regulation of progesterone receptors occurs if progesterone availability in the body is reduced. All the observed changes in combination may have negative consequences for reproduction and reproductive behavior later in life.

Next step in the development of mesoprogestins: the preclinical profile of EC313.

The pharmacological target for progesterone, different progestins, and Selective Progesterone Receptor Modulators (SPRMs) is the nuclear progesterone receptor (PR). EC313 is a new member of a subgroup of SPRMs, mesoprogestins, which combine especially PR- agonistic and PR-antagonistic activities in one molecule. The suitable in vivo-model for the differentiation of SPRMs from the subgroup of mesoprogestins is the estrogen-primed juvenile rabbit endometrium assay (McPhail Assay). Remarkably, in contrast to other well-known SPRMs with no agonistic effects in this test, EC313 shows clear partial PR-agonistic effects that are higher than that of the well-known mesoprogestin Asoprisnil which already demonstrated remarkable clinical effectiveness for the treatment of uterine fibroids and endometriosis. The findings from the guinea pig studies presented here can be the impetus for further preclinical development of EC313. This model shows the same features for the termination of pregnancy by antiprogestins such as Mifepristone and Ulipristal acetate (UPA) in humans. Moreover, it is possible to distinguish between progestational and anti-progestational activities in the same experiment. The EC313 treatment reveals PR dominance in the genital tract and inhibits unopposed estrogenic effects. In very high doses (30.0 mg/animal/day subcutaneously (s.c.)) given twice on pregnancy days 43 and 44, no premature labor was induced (in contrast to UPA, dosed at 10.0 and 30. mg/animal/day s.c.). The anti-ovulatory activity of EC313 exceeds that of Ulipristal acetate or Mifepristone. EC313 binds to the steroid receptors in vitro with a similar affinity as the natural ligand progesterone. At the glucocorticoid receptor (GR) EC313 acts as a weak inhibitor. Minor activities at the human androgen receptor (AR) and mineralocorticoid receptor (MR) are considered negligible. No binding to the estradiol receptor was detected. In contrast to some in vitro-receptor findings, estrogenic, anti-estrogenic, androgenic, anti-androgenic, glucocorticoid, and anti-glucocorticoid actions were absent in vivo. The tissue selectivity of EC313 was demonstrated previously by reducing the growth and proliferation of uterine fibroids in animal models (lowest effective dosage 0.1 mg/kg/day s.c.).. As shown in this article, the anti-fibroid activity of EC313 was confirmed with a 10 times lower dosage (0.01 mg/kg/day s.c.). It was also shown that EC313 reduces the growth of endometriotic lesions in a human xenograft immune-deficient (NOD-SCID) mice model with a comparatively very low dosage range. In the aforementioned EC313 activity model, UPA was tested as the reference compound, the clinical effectiveness of which has already been demonstrated. For an explanation of these findings, the possibility is discussed that the mixed agonistic/antagonistic feature of EC313 is tissue target-specific based on its super-additive synergism characteristic for active bifunctional agents. In conclusion, the specific pharmacodynamic profile of this compound opens the possibility for the development of a drug with a distinct pharmaco-endocrinological profile against uterine fibroids, endometriosis, and other PR-dependent gynecological diseases.

Validation of a new Custom Polyclonal Progesterone Receptor Antibody for Immunohistochemistry in the Female Mouse Brain.

Immunohistochemical visualization of progesterone receptor (PR)-expressing cells in the brain is a powerful technique to investigate the role of progesterone in the neuroendocrine regulation of fertility. A major obstacle to the immunohistochemical visualization of progesterone-sensitive cells in the rodent brain has been the discontinuation of the commercially produced A0098 rabbit polyclonal PR antibody by DAKO. To address the unavailability of this widely used PR antibody, we optimized and evaluated 4 alternative commercial PR antibodies and found that each lacked the specificity and/or sensitivity to immunohistochemically label PR-expressing cells in paraformaldehyde-fixed female mouse brain sections. As a result, we developed and validated a new custom RC269 PR antibody, directed against the same 533-547 amino acid sequence of the human PR as the discontinued A0098 DAKO PR antibody. Immunohistochemical application of the RC269 PR antibody on paraformaldehyde-fixed mouse brain sections resulted in nuclear PR labeling that was highly distinguishable from background, specific to its antigen, highly regulated by estradiol, matched the known distribution of PR protein expression in the female mouse hypothalamus, and nearly identical to that of the discontinued A0098 DAKO PR antibody. In summary, the RC269 PR antibody is a specific and sensitive antibody to immunohistochemically visualize PR-expressing cells in the mouse brain.

Decreased renal expression of PAQR5 is associated with the absence of a nephroprotective effect of progesterone in a rat UUO model

Fibrosis is a severe complication of chronic kidney disease (CKD). Progesterone, like other sex hormones, plays an important role in renal physiology, but its role in CKD is poorly understood. We investigated progesterone effect on renal fibrosis progression in the rat model of unilateral ureteral obstruction (UUO). Female rats were exposed to UUO, ovariectomy and progesterone administration after UUO with ovariectomy. Expression of key fibrosis markers, proinflammatory cytokines, levels of membrane-bound (PAQR5) and nuclear (PGR) progesterone receptors, and matrix metalloproteinase (MMP) activity were analyzed in the obstructed and intact rat kidney. In all groups exposed to UUO, decreased PAQR5 expression was observed in the obstructed kidney while in the contralateral kidney, it remained unaffected. We found increased mRNA levels for profibrotic COL1A1, FN1, MMP2, TIMP1, TIMP2, proinflammatory IL1α, IL1β, and IL18, as well as elevated α-SMA and MMP9 proteins, collagen deposition, and MMP2 activity in all UUO kidneys. Progesterone had slight or no effect on the change in these markers. Thus, we demonstrate for the first time diminished sensitivity of the kidney to progesterone associated with renal fibrosis due to a severe decrease in PAQR5 expression that was accompanied by the lack of nephroprotection in a rat UUO model.

Effects of estradiol, progesterone or cAMP on expression of PGRMC1 and progesterone receptor in a xenograft model of human endometrium and in endometrial cell culture

Estradiol and progesterone are key regulators of the menstrual cycle. In the human endometrium, progesterone induces morphological changes required for blastocyst implantation. Dysregulated response to progesterone can lead to endometrial pathologies including uterine bleeding and endometriosis. Besides the canonical nuclear progesterone receptor (encoded by the PGR gene), alternative response pathways include Progesterone Receptor Membrane Component 1 (PGRMC1), suspected to be involved in pathogenesis of endometrial diseases. We previously reported the spatiotemporal profile of PGRMC1 expression in the human endometrium along the menstrual cycle, highlighting progressive increase and decrease during the proliferative and secretory phases, respectively. Here we directly addressed its regulation by estradiol and progesterone, with systematic comparison with regulation of PGR expression. We found a direct correlation between expression of both genes during the proliferative and secretory phases in the cycling endometrium, but not during the menstrual phase. In a xenograft model mimicking the cycle phases, estradiol significantly increased and progesterone significantly decreased PGR expression but changes were not significant for PGRMC1. Finally, we did not find any significant effect of the ovarian steroids on expression of PGR or PGRMC1 in primary culture of endometrial stromal cells, except for a small increase in PGR expression by estradiol. Altogether, our experiments do not allow a major advance in our understanding of the mechanisms of cyclic variation of PGRMC1 expression, in particular regarding potential regulation by the ovarian steroids.

Reevaluating the Role of Progesterone in Ovarian Cancer: Is Progesterone Always Protective?

Ovarian cancer (OC) represents a collection of rare but lethal gynecologic cancers where the difficulty of early detection due to an often-subtle range of abdominal symptoms contributes to high fatality rates. With the exception of BRCA1/2 mutation carriers, OC most often manifests as a post-menopausal disease, a time in which the ovaries regress and circulating reproductive hormones diminish. Progesterone is thought to be a "protective" hormone that counters the proliferative actions of estrogen, as can be observed in the uterus or breast. Like other steroid hormone receptor family members, the transcriptional activity of the nuclear progesterone receptor (nPR) may be ligand dependent or independent and is fully integrated with other ubiquitous cell signaling pathways often altered in cancers. Emerging evidence in OC models challenges the singular protective role of progesterone/nPR. Herein, we integrate the historical perspective of progesterone on OC development and progression with exciting new research findings and critical interpretations to help paint a broader picture of the role of progesterone and nPR signaling in OC. We hope to alleviate some of the controversy around the role of progesterone and give insight into the importance of nPR actions in disease progression. A new perspective on the role of progesterone and nPR signaling integration will raise awareness to the complexity of nPRs and nPR-driven gene regulation in OC, help to reveal novel biomarkers, and lend critical knowledge for the development of better therapeutic strategies.

The Effect of Progestins on Cytokine Production in the Peripheral Blood Mononuclear Cells of Menopausal Women and Their Luminol-Dependent Chemiluminescence.

Steroid hormones are the key regulators of inflammatory and autoimmune processes. The role of steroid hormones is mostly inhibitory in these processes. The expression of IL-6, TNFα, and IL-1β, as markers of inflammation, and TGFβ, as a marker of fibrosis, could be useful tools to predict the response of an individual's immune system to the different progestins suitable for the treatment of menopausal inflammatory disorders, including endometriosis. In this study, the progestins P4 and MPA, as well as the novel progestin gestobutanoyl (GB), which possess potent anti-inflammatory properties towards endometriosis, were studied at a fixed concentration of 10 µM. Their influence on the production of the above cytokines in PHA-stimulated peripheral blood mononuclear cells (PBMCs) during 24 h incubation was evaluated by ELISA. It was found that synthetic progestins stimulated the production of IL-1β, IL-6, and TNFα and inhibited TGFβ production, while P4 inhibited IL-6 (33% inhibition) and did not influence TGFβ production. In the MTT-viability test, P4 also decreased PHA-stimulated PBMC viability by 28% during 24 h incubation, but MPA and GB did not have any inhibitory or stimulatory effects. The luminol-dependent chemiluminescence (LDC) assay revealed the anti-inflammatory and antioxidant properties of all the tested progestins, as well as some other steroid hormones and their antagonists: cortisol, dexamethasone, testosterone, estradiol, cyproterone, and tamoxifen. Of these, tamoxifen showed the most pronounced effect on the oxidation capacity of PBMC but not on that of dexamethasone, as was expected. Collectively, these data demonstrate that PBMCs from menopausal women respond differently to P4 and synthetic progestins, most likely due to distinct actions via various steroid receptors. It is not only the progestin affinity to nuclear progesterone receptors (PR), androgen receptors, glucocorticoid receptors, or estrogen receptors that is important for the immune response, but also the membrane PR or other nongenomic structures in immune cells.