Progesterone Receptor A Research Articles

Correlation of NRF2 and progesterone receptor and its effects on ovarian cancer biology.

PurposeThis study aimed to investigate the potential prognostic impact of nuclear factor erythroid 2-related factor 2 (NRF2) and progesterone receptor A (PRA)/progesterone receptor B (PRB) in ovarian cancer patients which might be the rationale for putative new treatment strategies.Patients and methodsThe presence of NRF2 and PRA/PRB was investigated in 156 ovarian cancer samples using immunohistochemistry (IHC). Staining of NRF2 and PRA/PRB was rated using the semi-quantitative immunoreactive score (IR score, Remmele’s score) and correlated to clinical and pathological data. NRF2 and PRA/PRB expression were compared with respect to the overall survival (OS).ResultsNRF2 staining was different in both, the cytoplasm and nucleus between the histological subtypes (p=0.001 and p=0.02, respectively). There was a significant difference in the PRA expression comparing all histological subtypes (p=0.02). Histological subtypes showed no significant differences in the PRB expression. A strong correlation of cytoplasmic NRF2 and PRA expression was detected (cc=0.247, p=0.003) as well as of cytoplasmic NRF2 and PRB expression (cc=0.25, p=0.003), confirmed by immunofluorescence double staining. Cytoplasmic NRF2 expression was associated with a longer OS (median 50.6 vs 32.5 months; p=0.1) as it was seen for PRA expression (median 63.4 vs 33.1 months; p=0.08), although not statistically significant. In addition, high PRB expression (median 80.4 vs 32.5 months; p=0.04) and concurrent expression of cytoplasmic NRF2 and PRA were associated with a significantly longer OS (median 109.7 vs 30.6 months; p=0.02). The same relationship was also noted for NRF2 and PRB with improved OS for patients expressing both cytoplasmic NRF2 and PRB (median 153.5 vs 30.6 months; p=0.009). Silencing of NFE2L2 induced higher mRNA expression of PGR in the cancer cell line OVCAR3 (p>0.05) confirming genetic interactions of NRF2 and PR.ConclusionIn this study, the combination of cytoplasmic NRF2 and high PRA/PRB expression was demonstrated to be associated with improved overall survival in ovarian cancer patients. Further understanding of interactions within the NRF2/AKR1C1/PR pathway could open new additional therapeutic approaches.

Effects of progesterone receptor on proliferation of uterine leiomyoma cells.

In order to study the mechanism of the effect of progesterone receptor on the growth of primary uterine leiomyoma cells, the primary cells were extracted from uterine leiomyoma cells and identified by immunohistochemistry (IHC). Mitochondrial progesterone receptor-positive [PR-M(+)], mitochondrial progesterone receptor-negative [PR-M(-)], progesterone receptor A (PR-A) and progesterone receptor B (PR-B) were screened by Western blotting. Different concentrations of Mifepristone (MIF), a progesterone receptor antagonist, were used to interfere with PR-M(+) and PR-M(-) cell lines, respectively. Proliferation and apoptosis of PR-M(+) and PR-M(-) cell lines were detected by tetramethylazolyl blue method and flow cytometry, respectively. The expression of Caspase-3 and B-cell lymphoma 2 (Bcl-2) protein was detected by Western blotting. The results showed that the growth of PR-M(+) and PR-M(-) uterine leiomyoma cells was inhibited with the increase of MIF concentration. Furthermore, the proliferation inhibition rate and apoptosis rate were gradually increased. However, the expression of Caspase-3 protein on progesterone receptor M increased, while the expression of Bcl-2 decreased. Moreover, progesterone could induce progesterone receptor M to up-regulate apoptotic protein Caspase-3 and down-regulate anti-apoptotic protein Bcl-2, thus it could inhibit the apoptosis of primary cultured uterine leiomyoma cells and promote the proliferation of leiomyoma cells.

The Effect of Imbalanced Progesterone Receptor-A/-B Ratio on Gelatinase Expressions in Endometriosis.

BackgroundGelatinases degrade extracellular matrix (ECM) components to allow for physiological remodeling and contribute to pathological tissue destruction in endometriosis. It is known that the function of gelatinases is resistant to suppression by progesterone in endometriosis. The ability of progesterone to impact gene expression depends on the progesterone receptor-A/-B (PR-A/PR-B) ratio. An imbalanced PR-A/PR-B ratio in endometriotic tissue may be the result of the differential expression of MMP-2 and MMP-9, which could be important in the etiology and pathogenesis of the disease. Hence, we decided to study the association of PR-A/PR-B ratio and gelatinases expression in endometriosis.Materials and MethodsIn this prospective case-control study, we enrolled 40 women, 20 in the case group who were diagnosed with stage III/IV endometriosis and 20 normal subjects without endometriosis (controls) who referred to Royan Institute, Tehran, Iran during 2013-2014. We obtained 60 tissue samples [ectopic (n=20), eutopic (n=20), and normal endometrium (n=20)]. RNA was extracted from the tissue samples in order to analyze PR-A, PR-B, MMP-2, and MMP-9 mRNA levels through real-time polymerase chain reaction (PCR).ResultsThere was significantly lower expression of the PR-B isoform in ectopic tissues compared to the control (P=0.002) and eutopic endometrium (P=0.006) tissues. PR-A expression was higher, but not significantly so, in the same ectopic and eutopic endometrium tissues compared to the control tissues (P=0.643). There was significant over- expression of MMP-9 in ectopic samples compared to control (P=0.014) and eutopic endometrium (P=0.012) samples. The PR-A/PR-B ratio was not significantly higher in either eutopic or ectopic samples compared to the control samples (P=0.305).ConclusionOur findings support an altered PR-B expression in endometriosis, which may be associated with MMP-9 overexpression. This finding can be important for disease pathogenesis.

Alterations in progesterone receptor-A and progesterone receptor-B expression levels affect myometrial contractility in the pregnant mouse uterus

Alterations in progesterone receptor-A and progesterone receptor-B expression levels affect myometrial contractility in the pregnant mouse uterus

Gene expression profile and cancer-associated pathways linked to progesterone receptor isoform a (PRA) predominance in transgenic mouse mammary glands

BackgroundProgesterone receptor (PR) is expressed from a single gene as two isoforms, PRA and PRB. In normal breast human tissue, PRA and PRB are expressed in equimolar ratios, but isoform ratio is altered during malignant progression, usually leading to high PRA:PRB ratios. We took advantage of a transgenic mouse model where PRA isoform is predominant (PRA transgenics) and identified the key transcriptional events and associated pathways underlying the preneoplastic phenotype in mammary glands of PRA transgenics as compared with normal wild-type littermates.MethodsThe transcriptomic profiles of PRA transgenics and wild-type mammary glands were generated using microarray technology. We identified differentially expressed genes and analyzed clustering, gene ontology (GO), gene set enrichment analysis (GSEA), and pathway profiles. We also performed comparisons with publicly available gene expression data sets of human breast cancer.ResultsWe identified a large number of differentially expressed genes which were mainly associated with metabolic pathways for the PRA transgenics phenotype while inflammation- related pathways were negatively correlated. Further, we determined a significant overlap of the pathways characterizing PRA transgenics and those in breast cancer subtypes Luminal A and Luminal B and identified novel putative biomarkers, such as PDHB and LAMB3.ConclusionThe transcriptional targets identified in this study should facilitate the formulation or refinement of useful molecular descriptors for diagnosis, prognosis, and therapy of breast cancer.

Icariin impacts molecular changes in estrogen receptors but not other reproductive parameters in female mice

This study was conducted to assess the effects of icariin (ICA) an ingredient of Epimedium species, on reproductive parameters in mice. Serum, uterus and ovarian samples were collected after treatment. We determined the reproductive index (RI) and in vitro maturation (IVM) rates of oocytes. The serum was tested for 17b-estradiol (17b-E2) and progesterone (P4) using radioimmunoassay (RIA) and ovaries were analyzed for mRNA expression of Steroidogenic acute regulatory protein (Star), Cytochrome p450 family 19 subfamilies a polypeptide 1 (Cyp19a1) and 17b-hydroxysteroid dehydrogenase (Hsd17b1), genes using Real-time Quantitative RT-PCR (RT-qPCR). Protein expression of estrogen receptors (ER) a, b, and progesterone receptor A (PRA) were detected using western blot (WB). ERa from treatment group was increased (p less then 0.05) while ERb and PRA were decreased (p less then0.05). ICA regulated ovarian development through the estrogen receptor pathway. ERa expression was evidently increased and this may be the pathway that is utilized for its mode of action.

Abstract OT1-04-02: Mifepristone treatment for breast cancer patients expressing levels of progesterone receptor isoform A (PRA) higher than those of isoform B (PRB)

Abstract Seventy percent of breast cancers express estrogen (ER) and progesterone receptors (PR) and respond to antiestrogen therapies. Emerging evidence from experimental studies and human epidemiology, points to a relevant role for progestins in breast carcinogenesis and cancer growth. Others and we have proposed that there is a role for antiprogestins in the therapeutic armamentarium, but the challenge remains to identify which patients would benefit from targeting the PR in addition to ER. Preclinical data indicates that antiprogestins block cell proliferation and increase apoptosis only in ER+ breast cancers expressing levels of PRA higher than those of PRB. The aim of this study is to evaluate the therapeutic effects of Mifepristone (MFP) on breast cancer patients selected by their PRA/PRB isoform ratio, for 14 days in between core biopsy and surgery (MIPRA trial ClinicalTrials.gov Identifier: NCT02651844). Methods: This is an open label, interventional with single group assignment study. We perform core biopsies on menopausal patients with clinically palpable breast cancers larger than 1.5 cm to confirm diagnosis. We will assess the PRA/PRB ratio by western blotting in frozen samples and total PR in formalin-fixed samples by immunohistochemistry (IHC). Twenty eligible PR+ patients (PR > 50 %) with PRA/PRB ≥1.5 who have signed consent forms, and meet the inclusion criteria will be recruited. Patients will be treated for 14 days with MFP p.o 200 mg. Surgery will be performed on day 15. Samples will be frozen for molecular studies or fixed for IHC. The primary outcome is the evaluation of Ki-67 staining pre- and post treatment. Secondary outcomes include comparatively expression of proliferation/apoptosis/PR signaling markers in core and surgical biopsy samples. Other pre-specified outcomes include molecular profiling, study of liquid biopsies, mammography, and ultrasound studies. Wilcoxon signed rank test will be used to evaluate differences in biomarker expression between core biopsy and surgical samples of each patient. Citation Format: Liguori M, Lanari C, Gass H, Rojas P, Elia A, Martinez Vazquez P, Burruchaga J, Gonzalez P, Caillet Bois I, Ventura C, San Martin G, Castets A, Lovisi S, Acosta Haab G, Lamb C, Fabris V, Novaro V, Molinolo A. Mifepristone treatment for breast cancer patients expressing levels of progesterone receptor isoform A (PRA) higher than those of isoform B (PRB) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-04-02.

Control of Progesterone Receptor-A Transrepressive Activity in Myometrial Cells: Implications for the Control of Human Parturition.

Uterine quiescence during pregnancy is maintained by progesterone primarily via signaling mediated by the type-B progesterone receptor (PR-B) in myometrial cells. Withdrawal of PR-B-mediated progesterone activity is a principal trigger for labor. One mechanism for PR-B withdrawal is by inhibition of its activity by the type-A PR (PR-A) isoform in myometrial cells. We hypothesized that human parturition involves hormonal interactions that induce the capacity for PR-A to inhibit PR-B in myometrial cells and that pro-inflammatory cytokines are major regulators of this process. We tested this hypothesis in an immortalized human myometrial cell line, hTERT-HMA/B, in which levels of PR-A and PR-B can be experimentally controlled. We found that the capacity for PR-A to repress PR-B, assessed by activity of a transiently transfected reporter DNA controlled by the progesterone response element, and expression of FK506 binding protein 5 ( FKBP5) an endogenous PR-B responsive gene, was increased by serum supplementation and interleukin-1β. In pregnant uterus, FKBP5 was detected exclusively in myometrial cells and its expression decreased with advancing gestation and in association with the onset of labor at term. These findings suggest that in myometrial cells the repressive activity of PR-A on PR-B increases with advancing gestation and is induced by pro-inflammatory cytokines. This may be a key mechanism linking inflammation with the onset of labor.

Progesterone arrested cell cycle progression through progesterone receptor isoform A in pancreatic neuroendocrine neoplasm

In pancreatic neuroendocrine neoplasms (Pan-NEN) progesterone signaling has been shown to have both inhibitory and stimulatory effects on cell proliferation. The ability of progesterone to inhibit tumor proliferation is of particular interest and is suggested to be mediated through the less abundantly expressed progesterone receptor (PR) isoform A (PRA). To date the mechanistic processes underlying this inhibition of proliferation remain unclear. To examine the mechanism of PRA actions, the human Pan-NEN cell line QGP-1, that endogenously expresses PR isoform B (PRB) without PRA, was transfected with PRA. PRA transfection suppressed the majority of cell cycle related genes increased by progesterone including cyclin A2 (CCNA2), cyclin B1 (CCNB1), cyclin-dependent kinase 1 (CDK1) and cyclin-dependent kinase 2 (CDK2). Importantly, following progesterone administration cell cycle distribution was shifted to S and G2/M phases in the naïve cell line but in PRA-transfected cells, this effect was suppressed. To see if these mechanistic insights were confirmed in patient samples PRA, PRB, CCNA2, CCNB, CDK1 and CDK2 immunoreactivities were assessed in Pan-NEN cases. Higher levels of cell cycle markers were associated with higher WHO grade tumors and correlations between the markers suggested formation of cyclin/CDK activated complexes in S and G2/M phases. PRA expression was associated with inverse correlation of all cell cycle markers. Collectively, these results indicate that progesterone signals through PRA negatively regulates cell cycle progression through suppressing S and G2/M phases and downregulation of cell cycle phases specific cyclins/CDKs.

Methylation of progesterone receptor isoform A and B promoters in the reproductive system of cows.

The aim of this study was to investigate whether the promoters of progesterone receptor isoform A (PGRA) and B (PGRB) are methylated and to determine the percentage of methylation occurring for each isoform. Genomic DNA was isolated from the corpora lutea (CL) and endometrial slices from cows on Days 2-5, 6-10, 11-16 and 17-20 of the oestrous cycle. DNA was bisulphite-converted and amplified using methyl-specific polymerase chain reaction (PCR) with primers that detect both methylated and unmethylated sequences. The determination of the percentage of the methylation was performed using HpaII and MspI restriction enzymes. Methyl-specific PCR showed partial methylation of PGRA and PGRB promoters in the CL and endometrium during the oestrous cycle. Methylation for PGRA was between 15 and 17% and for PGRB was in the range of 6 to 7.7% during the oestrous cycle in the CL. In the endometrium, the methylation for PGRA was between 6 and 7.3% and for PGRB was between 3 and 4.8% during the oestrous cycle. The data obtained indicate that the higher promoter methylation of the PGRA isoform could be a mechanism for regulation of PGRA inhibitory activity against PGRB and, in this way, methylation may influence the regulation of progesterone action in the CL and endometrium.

Progesterone receptor A promotes invasiveness and metastasis of luminal breast cancer by suppressing regulation of critical microRNAs by estrogen

Distal metastasis of luminal breast cancer is frequent and incurable, yet the metastasis mechanisms are poorly understood. Estrogen, even at postmenopausal concentrations, suppresses invasiveness of luminal breast cancer cells through the estrogen receptor (ER). Invasive tumors overexpress the short progesterone receptor A (PR-A) isoform. Even at postmenopausal concentrations, progesterone activates PR-A, inducing invasiveness by counteracting estrogen's effects, particularly when cells are hypersensitized to progesterone by PR-A overexpression. To interrogate the role of this cross-talk in metastasis, we investigated selective cross-talk mechanisms of PR-A with ER. We developed a quantitative PCR-based lymph node infiltration assay to address the slowness of metastasis of tumor xenografts. We found that 15 microRNAs (miRNAs) are regulated by progesterone via PR-A, but not the longer PR-B isoform, with increased progesterone sensitivity when PR-A was overexpressed. Two of these miRNAs whose induction (miR-92a-3p) or repression (miR-26b-5p) by estrogen was suppressed by progesterone plus PR-A were critical for the PR-A-ER cross-talk causing a gene-regulatory pattern of invasiveness and metastasis and complete rescue of invasiveness in vitro Constitutive expression of miR-92a-3p or inhibition of miR-26b-5p profoundly suppressed metastasis. Finally, in primary breast tumors, PR-A expression was correlated negatively with miR-92a-3p expression and positively with miR-26b-5p expression. Therefore, hormonal cross-talk of PR-A with ER is probably a fundamental mechanism that enables metastasis of luminal breast cancer. Moreover, miRNA biomarkers of hyperactive PR-A may help predict metastatic potential of luminal breast tumors. Further, miR-92a-3p and miR-26b-5p may reveal target pathways for selective intervention to suppress hormone-regulated metastasis, both pre- and postmenopause.

Prediction of Relapse After Therapy Withdrawal in Women with Endometrial Hyperplasia: A Long-term Follow-up Study.

To investigate whether risk of relapse of endometrial hyperplasia persists many years after successful primary therapy and whether clinical or biological markers observed at primary diagnosis may predict relapse. A series of 57 women with endometrial hyperplasia received levonorgestrel-impregnated intrauterine system or oral progestin for three months during 1998-2000. Index biopsies were classified according to WHO1994 and D-score systems, and immunohistochemical staining for estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor A (PRA), progesterone receptor B (PRB), B-cell lymphoma 2/apoptosis regulator (BCL2), BCL2-associated X protein/apoptosis regulator (BAX), paired box 2 (PAX2), and phosphatase and tensin homolog (PTEN) reported as H-scores. Over a follow-up of 157.8 months, 23% (10/43) of patients experienced relapse. No correlation with age, body mass index, parity, WHO94 classification, or D-score was found. Only PRA (p=0.004) and PRB (p=0.038) showed certain correlation with relapse. Endometrial hyperplasia recurs many years after successful progestin therapy. Increased expression of PRB and reduced expression of PRA significantly correlated with relapse. Our results support the importance of continuous endometrial protection and the need for new clinical surveillance guidelines.

Molecular Signaling of Progesterone, Growth Hormone, Wnt, and HER in Mammary Glands of Dogs, Rodents, and Humans: New Treatment Target Identification.

Mammary tumors are the most common form of neoplasia in the bitch. Female dogs are protected when they are spayed before the first estrus cycle, but this effect readily disappears and is already absent when dogs are spayed after the second heat. As the ovaries are removed during spaying, ovarian steroids are assumed to play an essential role in tumor development. The sensitivity toward tumor development is already present during early life, which may be caused by early mutations in stem cells during the first estrus cycles. Later on in life, tumors arise that are mostly steroid-receptor positive, although a small subset of tumors overexpressing human epidermal growth factor 2 (HER2) and some lacking estrogen receptor, progesterone receptor (PR), and HER2 (triple negative) are present, as is the situation in humans. Progesterone (P4), acting through PR, is the major steroid involved in outgrowth of mammary tissue. PRs are expressed in two forms, the progesterone receptor A (PRA) and progesterone receptor B (PRB) isoforms derived from splice variants from a single gene. The dog and the whole family of canids have only a functional PRA isoform, whereas the PRB isoform, if expressed at all, is devoid of intrinsic biological activity. In human breast cancer, overexpression of the PRA isoform is related to more aggressive carcinomas making the dog a unique model to study PRA-related mammary cancer. Administration of P4 to adult dogs results in local mammary expression of growth hormone (GH) and wing less-type mouse mammary tumor virus integration site family 4 (Wnt4). Both proteins play a role in activation of mammary stem cells. In this review, we summarize what is known on P4, GH, and Wnt signaling in canine mammary cancer, how the family of HER receptors could interact with this signaling, and what this means for comparative and translational oncological aspects of human breast cancer development.

Progesterone Receptor Isoform Ratio: A Breast Cancer Prognostic and Predictive Factor for Antiprogestin Responsiveness

Compelling evidence shows that progestins regulate breast cancer growth. Using preclinical models, we demonstrated that antiprogestins are inhibitory when the level of progesterone receptor isoform A (PR-A) is higher than that of isoform B (PR-B) and that they might stimulate growth when PR-B is predominant. The aims of this study were to investigate ex vivo responses to mifepristone (MFP) in breast carcinomas with different PR isoform ratios and to examine their clinical and molecular characteristics. We performed human breast cancer tissue culture assays (n = 36) to evaluate the effect of MFP on cell proliferation. PR isoform expression was determined by immunoblotting (n = 282). Tumors were categorized as PRA-H (PR-A/PR-B ≥ 1.2) or PRB-H (PR-A/PR-B ≤ 0.83). RNA was extracted forRibo-Zero-Seq sequencing to evaluate differentially expressed genes.Subtypes and risk scores were predicted using the PAM50 gene set, the data analyzed using The Cancer Genome Atlas RNA-seq gene analysis and other publicly available gene expression data. Tissue microarrays were performed using paraffin-embedded tissues (PRA-H n = 53, PRB-H n = 24), and protein expression analyzed by immunohistochemistry.All statistical tests were two-sided. One hundred sixteen out of 222 (52.3%) PR+ tumors were PRA-H, and 64(28.8%) PRB-H. Cell proliferation was inhibited by MFP in 19 of 19 tissue cultures from PRA-H tumors. A total of 139 transcripts related to proliferative pathways were differentially expressed in nine PRA-H and seven PRB-H tumors. PRB-H and PRA-H tumors were either luminal B or A phenotypes, respectively ( P = .03). PRB-H cases were associated with shorter relapse-free survival (hazard ratio [HR] = 2.70, 95% confidence interval [CI] = 1.71 to 6.20, P = .02) and distant metastasis-free survival (HR = 4.17, 95% CI = 2.18 to 7.97, P < .001). PRB-H tumors showed increased tumor size ( P < .001), Ki-67 levels ( P < .001), human epidermal growth factor receptor 2 expression ( P = .04), high grades ( P = .03), and decreased total PR ( P = .004) compared with PRA-H tumors. MUC-2 ( P < .001) and KRT6A ( P = .02) were also overexpressed in PRB-H tumors. The PRA/PRB ratio is a prognostic and predictive factor for antiprogestin responsiveness in breast cancer.

Effect of menopause on hormonal receptors in ampullae of the fallopian tube with a special reference to the p53 signature.

ObjectivesAge-related changes in the expression of hormonal receptors have not been well examined in the fallopian tube (FT). We herein report the effect of menopause on the hormone receptors in ampullae of the FTs (AFTs), in comparison with cortical inclusion cysts (CICs) of the ovary.MethodsA total of 84 AFTs and 16 fimbriae of FTs, which were obtained from 26 premenopausal and 58 postmenopausal women; and 27 postmenopausal CICs were immunohistochemically studied for the expression of p53, Ki-67, estrogen receptor-alpha (ER-α), and progesterone receptor A (PRA). Apoptotic cells were identified using a TUNEL assay.ResultsPostmenopausal AFTs showed a significantly lower labeling index (LI) for Ki-67 (P<0.001), apoptosis (P=0.03), and PRA (P<0.001) than premenopausal AFTs. No significant correlation with immunohistochemical markers was found in premenopausal AFTs, but the LI for PRA was positively correlated with that for Ki-67 (P=0.004) and inversely with that for p53 (P=0.023) in postmenopausal AFTs. The expression of immunohistochemical markers was closely correlated between ampullae and fimbriae of the FT. The p53 signature (p53S) was detected in five postmenopausal AFTs (mean age: 70.2 years) and was not detected in any CICs. The immunohistochemical profile of p53S was low expression of Ki-67, apoptosis, and PRA, and high expression of ER-α. The expression of PRA in CICs was significantly higher than that in AFTs (P=0.001).ConclusionThe expression of PRA was significantly lower in postmenopausal AFTs than in premenopausal AFTs, whereas the expression of PRA was well preserved in postmenopausal CICs.

Versican Proteolysis by ADAMTS Proteases and Its Influence on Sex Steroid Receptor Expression in Uterine Leiomyoma.

Leiomyomas have abundant extracellular matrix (ECM), with upregulation of versican, a large proteoglycan. We investigated ADAMTS (a disintegrin-like and metalloprotease with thrombospondin type 1 motifs) protease-mediated versican cleavage in myometrium and leiomyoma and the effect of versican knockdown in leiomyoma cells. We used quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting, immunohistochemistry, and RNA in situ hybridization for analysis of myometrium, leiomyoma and immortalized myometrium and leiomyoma cells. Short interfering RNA (siRNA) was used to knockdown versican in leiomyoma cells. This study was performed in an academic laboratory. Study subjects were women with symptomatic or asymptomatic leiomyoma. We quantified messenger RNAs (mRNAs) for versican splice variants. We identified ADAMTS-cleaved versican in myometrium and leiomyoma and ADAMTS messenger RNAs and examined the effect of VCAN siRNA on smooth muscle differentiation and expression of estrogen and progesterone receptors. The women in the symptomatic group (n = 7) had larger leiomyoma (P = 0.01), heavy menstrual bleeding (P < 0.01), and lower hemoglobin levels (P = 0.02) compared with the asymptomatic group (n = 7), but were similar in age and menopausal status. Versican V0 and V1 isoforms were upregulated in the leiomyomas of symptomatic versus asymptomatic women (P = 0.03 and P = 0.04, respectively). Abundant cleaved versican was detected in leiomyoma and myometrium, as well as in myometrial and leiomyoma cell lines. ADAMTS4 (P = 0.03) and ADAMTS15 (P = 0.04) were upregulated in symptomatic leiomyomas. VCAN siRNA did not effect cell proliferation, apoptosis, or smooth muscle markers, but reduced ESR1 and PR-A expression (P = 0.001 and P = 0.002, respectively). Versican in myometrium, leiomyomas and in the corresponding immortalized cells is cleaved by ADAMTS proteases. VCAN siRNA suppresses production of estrogen receptor 1 and progesterone receptor-A. These findings have implications for leiomyoma growth.

Decreased epithelial progesterone receptor A at the window of receptivity is required for preparation of the endometrium for embryo attachment.

The precise timing of progesterone signaling through its cognate receptor, the progesterone receptor (PGR), is critical for the establishment and maintenance of pregnancy. Loss of PGR expression in the murine uterine epithelium during the preimplantation period is a marker for uterine receptivity and embryo attachment. We hypothesized that the decrease in progesterone receptor A (PGRA) expression is necessary for successful embryo implantation. To test this hypothesis, a mouse model constitutively expressing PGRA (mPgrALsL/+) was generated. Expression of PGRA in all uterine compartments (Pgrcre) or uterine epithelium (Wnt7acre) resulted in infertility with defects in embryo attachment and stromal decidualization. Expression of critical PGRA target genes, indian hedgehog, and amphiregulin (Areg), was maintained through the window of receptivity while the estrogen receptor target gene, the leukemia inhibitory factor (Lif), a key regulator of embryo receptivity, was decreased. Transcriptomic and cistromic analyses of the mouse uterus at day 4.5 of pregnancy identified an altered group of genes regulating molecular transport in the control of fluid and ion levels within the uterine interstitial space. Additionally, LIF and its cognate receptor, the leukemia inhibitory factor receptor (LIFR), exhibited PGR-binding events in regions upstream of the transcriptional start sites, suggesting PGRA is inhibiting transcription at these loci. Therefore, downregulation of the PGRA isoform at the window of receptivity is necessary for the attenuation of hedgehog signaling, transcriptional activation of LIF signaling, and modulation of solutes and fluid, producing a receptive environment for the attaching embryo.

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.

Human Parturition Involves Phosphorylation of Progesterone Receptor-A at Serine-345 in Myometrial Cells.

The hypothesis that phosphorylation of progesterone receptor (PR) isoforms, PR-A and PR-B, in myometrial cells affects progesterone action in the context of human parturition was tested. Immunodetection of phosphoserine (pSer) PR forms in term myometrium revealed that the onset of labor is associated with increased phosphorylation of PR-A at serine-345 (pSer345-PRA) and that pSer345-PRA localized to the nucleus of myometrial cells. In explant cultures of term myometrium generation of pSer345-PRA was induced by interleukin-1β and dependent on progesterone, suggesting that pSer345-PRA generation is induced by a proinflammatory stimulus. In the hTERT-HMA/B human myometrial cell line, abundance of pSer345-PRA was induced by progesterone in a dose- (EC50 ∼1 nM) and time-dependent manner. Prevention of pSer345 (by site-directed mutagenesis) abolished the capacity for PR-A to inhibit anti-inflammatory actions of progesterone mediated by PR-B but had no effect on the transrepressive activity of PR-A at a canonical progesterone response element. Taken together, the data show that human parturition involves the phosphorylation of PR-A at serine-345 in myometrial cells and that this process is ligand dependent and induced by a proinflammatory stimulus. We also found that in myometrial cells, pSer345 activates the capacity for PR-A to inhibit antiinflammatory actions of progesterone mediated by PR-B. Phosphorylation of PR-A at serine-345 may be an important functional link between tissue-level inflammation and PR-A-mediated functional progesterone withdrawal to trigger parturition.

Abstract 1102: miRNAs are key mediators of crosstalk between estrogen and progesterone regulating breast cancer invasiveness

Abstract Even though estrogen receptor (ER)-positive breast tumors are exquisitely sensitive to anti-estrogen therapy, the disease is virtually incurable when it has progressed to ER+ distal metastasis. Therefore a better understanding of regulatory processes in ER+ breast tumor invasiveness is important. Invasive ER+ breast tumors frequently express high levels of the progesterone receptor (PR) isoform A (PR-A), relative to PR-B. We have previously reported that E2 strongly represses in vitro invasiveness below concentrations of E2 corresponding to median plasma and breast tissue levels post-menopause. Progesterone, at concentrations corresponding to postmenopausal levels, completely abrogates inhibition of invasiveness by E2. The ability of progestins to rescue invasiveness from estrogen regulation is exclusively mediated by PR-A. In contrast, at the high concentrations associated with luteal phase and pregnancy levels, progesterone induces invasiveness independent of E2 through PR-B. Interventions that target PR-A are limited by the fact that functional PR-A is needed to protect against E2-induced uterine dysplasia and hyperplasia. In order to attenuate PR-A dependent invasiveness, it is necessary to identify and target mediators of specific cross-talk between E2/ER and progestin/PR-A in the context of hormonal regulation of invasiveness. As micro-RNAs (miRs) are known to play a major role in the actions of E2, we investigated two possible modalities for miRs to mediate this cross talk: (1) Progesterone/PR-A could induce expression of critical miRs that attenuate suppressive effects of E2 on invasiveness; (2) E2-regulated miRs that directly influence invasiveness may be counter-regulated by progesterone/PR-A. Using microarray analysis and quantitative PCR in several ER+ cell lines, we identified five miRs (miR-6805, miR-584, miR-1228, miR-501, and miR-668) that were activated by progestin exclusively by PR-A, but were not regulated by E2. Whereas these miRs could serve as a signature of hyperactive PR-A, loss-of-function studies using miR inhibitors indicated that they did not play a functional role in the ability of PR-A to regulate invasiveness. An additional ten miRs were regulated by E2/ER (activated or repressed), in a manner that was counter-regulated by progestin/PR-A. Two of these miRs (miR-92a, and miR-26b) were identified using miR inhibitors to have a direct role in mediating the ability of progesterone to rescue invasiveness from E2 regulation. In conclusion, this study has provided a potential diagnostic miR signature of hyper-active PR-A and has also identified two miRs that could potentially be targeted to attenuate breast tumor invasiveness supported by progesterone/PR-A. Citation Format: Thomas B. McFall. miRNAs are key mediators of crosstalk between estrogen and progesterone regulating breast cancer invasiveness. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1102.