Progesterone Receptor Protein Research Articles

Affinity-tagged SMAD1 and SMAD5 mouse lines reveal transcriptional reprogramming mechanisms during early pregnancy.

Endometrial decidualization, a prerequisite for successful pregnancies, relies on transcriptional reprogramming driven by progesterone receptor (PR) and bone morphogenetic protein (BMP)-SMAD1/SMAD5 signaling pathways. Despite their critical roles in early pregnancy, how these pathways intersect in reprogramming the endometrium into a receptive state remains unclear. To define how SMAD1 and/or SMAD5 integrate BMP signaling in the uterus during early pregnancy, we generated two novel transgenic mouse lines with affinity tags inserted into the endogenous SMAD1 and SMAD5 loci (Smad1HA/HA and Smad5PA/PA). By profiling the genome-wide distribution of SMAD1, SMAD5, and PR in the mouse uterus, we demonstrated the unique and shared roles of SMAD1 and SMAD5 during the window of implantation. We also showed the presence of a conserved SMAD1, SMAD5, and PR genomic binding signature in the uterus during early pregnancy. To functionally characterize the translational aspects of our findings, we demonstrated that SMAD1/5 knockdown in human endometrial stromal cells suppressed expressions of canonical decidual markers (IGFBP1, PRL, FOXO1) and PR-responsive genes (RORB, KLF15). Here, our studies provide novel tools to study BMP signaling pathways and highlight the fundamental roles of SMAD1/5 in mediating both BMP signaling pathways and the transcriptional response to progesterone (P4) during early pregnancy.

Affinity-tagged SMAD1 and SMAD5 mouse lines reveal transcriptional reprogramming mechanisms during early pregnancy

Endometrial decidualization, a prerequisite for successful pregnancies, relies on transcriptional reprogramming driven by progesterone receptor (PR) and bone morphogenetic protein (BMP)-SMAD1/SMAD5 signaling pathways. Despite their critical roles in early pregnancy, how these pathways intersect in reprogramming the endometrium into a receptive state remains unclear. To define how SMAD1 and/or SMAD5 integrate BMP signaling in the uterus during early pregnancy, we generated two novel transgenic mouse lines with affinity tags inserted into the endogenous SMAD1 and SMAD5 loci (Smad1HA/HA and Smad5PA/PA). By profiling the genome-wide distribution of SMAD1, SMAD5, and PR in the mouse uterus, we demonstrated the unique and shared roles of SMAD1 and SMAD5 during the window of implantation. We also showed the presence of a conserved SMAD1, SMAD5, and PR genomic binding signature in the uterus during early pregnancy. To functionally characterize the translational aspects of our findings, we demonstrated that SMAD1/5 knockdown in human endometrial stromal cells suppressed expressions of canonical decidual markers (IGFBP1, PRL, FOXO1) and PR-responsive genes (RORB, KLF15). Here, our studies provide novel tools to study BMP signaling pathways and highlight the fundamental roles of SMAD1/5 in mediating both BMP signaling pathways and the transcriptional response to progesterone (P4) during early pregnancy.

Abstract 6577: Chemoproteomic evaluation of PROTACs targeting estrogen receptor alpha for ER+ breast cancer

Abstract In our investigation of estrogen receptor (ER) targeted protein degraders for advanced ER+ breast cancer, we assessed three proteolysis targeting chimeras (PROTACs), ARV471, ERD308, and ERD3111. Global proteomic analysis unveiled off-target protein degradation of progesterone receptor (PR) and phosphodiesterase 6D (PDE6D) by ER targeted PROTACs, but not selective ER degraders (SERDs). PR and PDE6D have previously been implicated as targets in cancer treatment. Protein degradation is rescued in CRBN- or VHL-knockout cells. Co-treating ER+ breast cancer cells with ligands for PR or PDE6D outcompeted PROTAC-mediated degradation and stabilized the respective protein, demonstrating the PROTACs are targeting the PR and PDE6D ligand-binding domains. Competition assays in ER-negative cell lines confirmed PR and PDE6D protein degradation is ER-independent. These findings underscore the importance of understanding off-target effects for developing more selective and effective therapeutics in ER+ breast cancer. Citation Format: Zachary Sandusky, Myles Brown. Chemoproteomic evaluation of PROTACs targeting estrogen receptor alpha for ER+ breast 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 6577.

Defining the relationship between cellular and extracellular vesicle (EV) content in breast cancer via an integrative multi-omic analysis.

Much recent research has been dedicated to exploring the utility of extracellular vesicles (EVs) as circulating disease biomarkers. Underpinning this work is the assumption that the molecular cargo of EVs directly reflects the originating cell. Few attempts have been made, however, to empirically validate this on the -omic level. To this end, we have performed an integrative multi-omic analysis of a panel of breast cancer cell lines and corresponding EVs. Whole transcriptome analysis validated that the cellular transcriptome remained stable when cultured cells are transitioned to low serum or serum-free medium for EV collection. Transcriptomic profiling of the isolated EVs indicated a positive correlation between transcript levels in cells and EVs, including disease-associated transcripts. Analysis of the EV proteome verified that HER2 proteinis present in EVs, however neither the estrogen (ER) nor progesterone (PR) receptor proteins are detected regardless of cellular expression. Using multivariate analysis, we derived an EV protein signature to infer cellular patterns of ER and HER2 expression, though the ER protein could not be directly detected. Integrative analyses affirmed that the EV proteome and transcriptome captured key phenotypic hallmarks of the originating cells, supporting the potential of EVs for non-invasive monitoring of breast cancers.

Expression of oestrogen and progesterone receptor and intermediate filament proteins in the oviduct of mares with endometrosis

Equine endometrosis is one of the major causes of equine infertility, in the course of which periglandular fibrosis signs occur in the endometrium. As an oviduct is a key place of early embryo development, we hypothesized that loss of contact between mucosal cells and perturbation in hormonal action may coexist in the uterus and oviducts. Thus, this study aimed to investigate the expression of the intermediate filaments (vimentin and desmin) as well as the estrogen receptor alpha (ERα) and progesterone receptor A (PRA) in the stroma and epithelia of endometrium and oviduct in healthy mares and these with endometrosis. Out of 56 culled-in slaughterhouse mare endometrium samples were annotated in two groups (i) healthy endometrium (n=26) and endometrium with signs of moderate and severe endometrosis (n=20). The expression of vimentin, desmin, ERα, and PRA was investigated immunohistochemically and compared between the above groups as well as between the phase of the estrous cycle. The expression of both vimentin and desmin was higher in the endometrial stroma of endometrosis group compared to healthy endometrium. The expression of ERα was higher in the healthy endometrial stroma and luminal epithelium during the follicular phase than luteal, however, no differences were noted in endometrium of mares with endometrosis. Moreover, PRA expression was significantly higher in the stoma oviduct during the follicular phase than luteal. It seems possible that mucosal cells through their altered interactions may support the occurrence of moderate and severe endometrosis. In addition, the oviduct appears to be less sensitive to hormonal changes than the uterus. The changed expression of intermediate filaments and steroid hormones may be some of the leading factors which can contribute to the oviduct functional status in endometrosis.

Progesterone and cAMP synergistically induce SHP2 expression via PGR and CREB1 during uterine stromal decidualization.

Decidualization of endometrial stroma is a key step in embryo implantation and its abnormality often leads to pregnancy failure. Stromal decidualization is a very complex process that is co-regulated by estrogen, progesterone and many local factors. The signaling protein SHP2 encoded by PTPN11 is dynamically expressed in decidualized endometrial stroma and mediates and integrates various signals to govern the decidualization. In the present study, we investigate the mechanism of PTPN11 gene transcription. Estrogen, progesterone and cAMP co-induced decidualization of human endometrial stromal cell in vitro, but only progesterone and cAMP induced SHP2 expression. Using the luciferase reporter, we refined a region from -229 bp to +1 bp in the PTPN11 gene promoter comprising the transcriptional core regions that respond to progesterone and cAMP. Progesterone receptor (PGR) and cAMP-responsive element-binding protein 1 (CREB1) were predicted to be transcription factors in this core region by bioinformatic methods. The direct binding of PGR and CREB1 on the PTPN11 promoter was confirmed by electrophoretic mobility and chromatin immunoprecipitation in vitro. Knockdown of PGR and CREB1 protein significantly inhibited the expression of SHP2 induced by medroxyprogesterone acetate and cAMP. These results demonstrate that transcription factors PGR and CREB1 bind to the PTPN11 promoter to regulate the expression of SHP2 in response to decidual signals. Our results explain the transcriptional expression mechanism of SHP2 during decidualization and promote the understanding of the mechanism of decidualization of stromal cells.

INSILICO DETERMINATION OF ANTI CANCER ACTIVITY OF PHYTOCHEMICAL FROM CLOVE (Syzygium aromaticum L) SEED

Syzygium aromaticum seed from the family of Myrtaceae is a highly priced natural spice used in preparation of food which have been acclaimed and reported by previous researchers to have anticancer activities potentials. Due to the rising burden of cancer worldwide its severity and fatality coupled with side effects of synthetic drugs calls for an alternative treatment solution. Hence the current research studied the phytocompounds from the seed by extracting and screening the compounds using solvent maceration method and gas chromatography coupled to mass selective detector respectively to extract, identify and quantify the component phytochemicals present in the seed. Site directed multi-ligand docking of the identified compounds was performance on progesterone receptor protein responsible for breast cancer development using the compounds from GCMS results and compared with four standard breast cancer drugs by molecular docking method. The result showed that the alpha cubebene (-7 kcal/mol), Velerena -4, 7- (II) diene (-7.1 kcal/mol), caryophyllene (-7.4 kcal/mol), caryophyllene oxide (-7.4 kcal/mol), dibutyl phthalate have binding affinity close to the standard breast cancer drugs Abemaciclib (-8.3), Anastrozole (-7.2 kcal/mol) and Paclitaxel (-8.8 kcal/mol) and they have better binding affinity than the drug Cyclophasphamide (-5.6 kcal/mol). The result also revealed that some compounds from the GC-MS were found to have a binding affinity closer tothat of thecocrystallized ligand (-10.7 kcal/mol). Other compounds from clove seed showed favourable docking scores in comparison with the drugs as many of the compounds have docking scores of more than (-6 kcal/mol) suggesting that the compounds have anti breast cancer activities since their amino acids showed hydrogen bonding corresponding to that on the binding site

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.

Jiawei Shoutai Pill promotes decidualization by regulating the SGK1/ENaC pathway in recurrent spontaneous abortion

Ethnopharmacological relevanceJiawei Shoutai Pill (JWSTW) is a traditional herbal formula for recurrent spontaneous abortion (RSA). Although JWSTW significantly improves the clinical symptoms of RSA patients, its molecular mechanism remains unclear. Aim of studyThis study evaluated the expression and function of the serum/glucocorticoid regulated kinase 1/epithelial sodium channel (SGK1/ENaC) pathway and decidualization level in RSA patients and mice. It also investigated the therapeutic effects and potential mechanisms of JWSTW. Materials and methods30 early RSA patients and 30 normal pregnant women undergoing induced abortion during the same period were included in the study. Decidual tissues were collected, and HE staining, immunohistochemistry, Western blot, and RT-PCR were used to detect protein and mRNA expression levels of SGK1, ENaC-a, estrogen Rreceptor β (ERβ), and progesterone receptor (PR) in patients’ decidual tissues. Protein expression levels of prolactin receptor (PRLR) and insulin-like growth factor binding protein 1 (IGFBP-1) were also detected. A classical RSA mouse model was constructed, and the mice were randomly divided into four groups: normal, model, dydrogesterone (DQYT) (0.33 g/kg/d), and JWSTW (1.66 g/kg/d). The normal and model groups received the same volume of distilled water by gavage for 8 and 14 days after pregnancy. On the 14th day of pregnancy, the embryonic loss rate of each group, the number of offspring born to naturally delivered mice, and the protein or mRNA expression levels of key factors of the SGK1/ENaC pathway (SGK1, ENaC-a, ERβ, and PR), decidual proliferation marker (Ki67), mesenchymal-epithelial transition (E-cadherin and Vimentin), and decidualization markers (PRLR and IGFBP-1) in mouse decidual tissue on the eighth day of pregnancy were observed. ResultsThe decidual tissue structure of RSA patients was abnormal. Immunohistochemical analysis revealed significantly reduced positive expression of SGK1, ENaC-a, ERβ, and PR proteins in the decidual tissue of RSA patients (P < 0.001). Western blot and RT-PCR analyses demonstrated significantly decreased protein and mRNA expression of SGK1, ENaC-a, ERβ, and PR in the decidual tissue of RSA patients (all P < 0.05). Additionally, protein expression of PRLR and IGFBP-1 was significantly reduced (both P < 0.001). The RSA mouse model exhibited a significant increase in embryo loss rate and decreased litter size (both P < 0.001). Treatment with DQYT and JWSTW rescued the embryo loss rate and litter size to varying extents (all P < 0.05). The protein or mRNA expression levels of SGK1, ENaC-a, ERβ, PR, Ki67, E-cadherin, vimentin, PRLR, and IGFBP-1 in RSA mice were improved to different degrees after treatment with DQYT and JWSTW (all P < 0.05). ConclusionsAbnormal SGK1/ENaC signaling pathway regulation is closely associated with early endometrial damage in RSA patients. JWSTW promotes endometrial proliferation and mesenchymal-epithelial transition through the SGK1/ENaC signaling pathway, improving endometrial shedding. Consequently, JWSTW is a potential treatment for RSA.

The association of progesterone receptor and abnormal p53 expression in endometrioid endometrial cancer.

e17611 Background: Based on the TCGA endometrial cancer study results, a clinically applicable classification that identifies distinct subgroups with prognostic signature, the Proactive Molecular Risk Classifier for Endometrial Cancer (ProMisE), has been built and validated. It shows that those with abnormal expression of p53 (p53abn) are the group with the worst prognosis. We attempted to explore the association of p53abn and progesterone receptor (PR) in endometrioid endometrial cancer. Methods: We included 397 consecutive endometrial cancer cases of endometrioid histology with adequate tumor tissue in the formalin-fixed, paraffin-embedded (FFPE) block and available follow-up information. This study was granted by Chang Gung Medical Foundation IRB 201702242B0D001. Sanger sequencing to assess the POLE exonuclease domain hotspot mutations of exon 9-14 and immunohistochemical staining on FFPE tumor tissue sections for p53, ER, PR, and mismatch repair proteins were performed. Immunohistochemical p53 expression of cancer cell nucleus was recorded as completely negative (0%), weakly positive (1-59%), and diffusely strong positive (&gt;60%). Tumors with weak positive p53 staining were defined as p53 wild type (p53wt), while the other two were defined as p53 abnormal (p53abn). PR scores were calculated by multiplying the average staining intensity by the tumor cell nucleus stained percentage. We arbitrarily defined a progesterone receptor score of 100 or higher as positive (PR+). Progression-free and endometrial cancer-specific overall survivals starting at the date of diagnosis were evaluated using Kaplan-Meier method and compared by log-rank test between groups. Results: PR was positive in 82% of all studied cases. Of the 48 cases with p53abn tumor, 35(73%) were PR (+). With a median follow-up of 74 months, the progression-free survival and cancer-specific survival of patients with PR+ tumors (N = 310) were 93% and 96.8%, respectively, compared with 75% and 85.7% of those with PR- tumors (N = 70) (both p &lt; 0.001, log-rank test). Among those with P53abn, PR expression was associated with a favorable progression-free survival ( p = 0.081) and better cancer-specific survival ( p = 0.044). POLEmut, POLE mutated; dMMR, deficient mismatch repair PR+, progesterone receptor score ≥100, ER+, estrogen receptor score ≥100; p53abn, abnormal p53 expression. MMR was undetermined in 32 cases, PR in 17 cases, ER in 17 cases, and p53 was undetermined in 10 cases. POLE status was detected in all cases. Cases with POLE wild type, proficient mismatch repair, progesterone score &lt; 100, estrogen score &lt; 100 and wild type p53 were not listed in this table. Conclusions: Our study showed that incorporating PR into prognostic molecular markers for endometrioid endometrial cancer might provide further risk stratification. [Table: see text]

Innovative thiosemicarbazones that induce multi-modal mechanisms to down-regulate estrogen-, progesterone-, androgen- and prolactin-receptors in breast cancer

The estrogen receptor-α (ER-α) is a key driver of breast cancer (BC) and the ER-antagonist, tamoxifen, is a central pillar of BC treatment. However, cross-talk between ER-α, other hormone and growth factor receptors enables development of de novo resistance to tamoxifen. Herein, we mechanistically dissect the activity of a new class of anti-cancer agents that inhibit multiple growth factor receptors and down-stream signaling for the treatment of ER-positive BC. Using RNA sequencing and comprehensive protein expression analysis, we examined the activity of di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) and di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), on the expression and activation of hormone and growth factor receptors, co-factors, and key resistance pathways in ER-α-positive BC. DpC differentially regulated 106 estrogen-response genes, and this was linked to decreased mRNA levels of 4 central hormone receptors involved in BC pathogenesis, namely ER, progesterone receptor (PR), androgen receptor (AR), and prolactin receptor (PRL-R). Mechanistic investigation demonstrated that due to DpC and Dp44mT binding metal ions, these agents caused a pronounced decrease in ER-α, AR, PR, and PRL-R protein expression. DpC and Dp44mT also inhibited activation and down-stream signaling of the epidermal growth factor (EGF) family receptors, and expression of co-factors that promote ER-α transcriptional activity, including SRC3, NF-κB p65, and SP1. In vivo, DpC was highly tolerable and effectively inhibited ER-α-positive BC growth. Through bespoke, non-hormonal, multi-modal mechanisms, Dp44mT and DpC decrease the expression of PR, AR, PRL-R, and tyrosine kinases that act with ER-α to promote BC, constituting an innovative therapeutic approach.

Atretic preovulatory follicles could be precursors of ovarian lutein cysts in the pig

Ovarian cysts contribute to reduced reproductive performance in pigs. Unfortunately, the mechanism of lutein cysts formation remains unknown. Here, we compared the endocrine and molecular milieus of intact, healthy preovulatory follicles (PF), gonadotropin (eCG/hCG)-induced healthy and atretic-like PF, as well as gonadotropin-provoked and spontaneous ovarian cysts in gilts. Several endocrine and molecular indicators and microRNA were compared in walls of PF and cysts. Intact and healthy PF, showed high estradiol/androstendione and low progesterone levels associated with CYP17A1, HSD17B1, and CYP19A1 elevation and reduced StAR/HSD3B1 protein expression. In contrast, low estradiol/androstendione and high progesterone concentrations, accompanied by decreased CYP17A1, HSD17B1, CYP19A1 and increased HSD3B1 protein abundance, appeared in atretic-like PF, gonadotropin-induced and spontaneous cysts. High progesterone receptor (PGR) protein abundance was maintained in intact and healthy PF, while it dropped in atretic-like PF, gonadotropins-induced and spontaneous cysts. The atretic PF showed high level of TNFα compared to healthy PF. In conclusion, follicular lutein cysts could be recruited from atretic-like PF with lost estrogenic milieu and inability to ovulate. Ovulatory cascade was presumably disrupted by a low PGR and high TNFα levels associated with earlier luteinization of follicular walls. These results suggest a novel mechanism of lutein ovarian cysts development in pigs and, perhaps, other species.

Intrauterine administration of autologous peripheral blood mononuclear cells regulates the endometrium estrogen and progesterone receptor expression: An RCT.

Repeated implantation failure (RIF) affects 15% of women of reproductive age. There is a high endometrial expression of both estrogen receptors and progesterone receptors (PRs) during the window of implantation in women with RIF. To evaluate the effects of intrauterine administration of human peripheral blood mononuclear cells (PBMC) on estrogen receptor α (ERα) and PRs expression in the endometrium of women with RIF during the implantation window. This randomized clinical trial study was conducted on 22 women with RIF history from January 2018 to August 2019 in Erfan hospital, Tehran, Iran. Participantswere divided into 2 groups (PBMC-treated group [n = 11] and control group [n = 11]). Endometrial tissue samples were collected at the implantation window time, during the mid-secretory phase (luteinizing hormone surge +7 days) of each menstrual cycle. The quantitative real-time polymerase chain reaction technique was used to measure the mRNA levels of ERα and PRs isoforms (PR-A and PR-B) in endometrial tissues. Furthermore, the protein expression of ERα and PRs was investigated using immunohistochemical staining. PBMC treatment significantly decreased the mRNA expression of endometrial ERα and PRs isoforms at the time of the implantation window (p 0.001). Moreover, the endometrial ERα and PRs protein localization were significantly lower in PBMC-treated women compared with controls (p = 0.01, and p 0.001 respectively). The intrauterine administration of PBMC decreased the endometrial ERα and PRs expression during the window of implantation in women with RIF. This local response to PBMC therapy could promote endometrial receptivity and embryo implantation.

Clinicopathological features and prognoses of very young patients (≤35 years) with breast cancer: a retrospective population-based study in China.

Clinicopathological features and prognoses of very young patients (≤35 years) with breast cancer: a retrospective population-based study in China.

METTL3 is essential for normal progesterone signaling during embryo implantation via m6A-mediated translation control of progesterone receptor

Embryo implantation, a crucial step in human reproduction, is tightly controlled by estrogen and progesterone (P4) via estrogen receptor alpha and progesterone receptor (PGR), respectively. Here, we report that N6-methyladenosine (m6A), the most abundant mRNA modification in eukaryotes, plays an essential role in embryo implantation through the maintenance of P4signaling. Conditional deletion of methyltransferase-like 3 (Mettl3), encoding the m6A writer METTL3, in the female reproductive tract using a Cre mouse line with Pgr promoter (Pgr-Cre) resulted in complete implantation failure due to pre-implantation embryo loss and defective uterine receptivity. Moreover, the uterus of Mettl3 null mice failed to respond to artificial decidualization. We further found that Mettl3 deletion was accompanied by a marked decrease in PGR protein expression. Mechanistically, we found that Pgr mRNA is a direct target for METTL3-mediated m6A modification. A luciferase assay revealed that the m6A modification in the 5' untranslated region (5'-UTR) of Pgr mRNA enhances PGR protein translation efficiency in a YTHDF1-dependent manner. Finally, we demonstrated that METTL3 is required for human endometrial stromal cell decidualization invitro and that the METTL3-PGR axis is conserved between mice and humans. In summary, this study provides evidence that METTL3 is essential for normal P4 signaling during embryo implantation via m6A-mediated translation control of Pgr mRNA.

Evolving perspectives on the treatment of HR+/HER2+ metastatic breast cancer.

Breast cancer (BC) with expression of the estrogen receptor (ER) and/or progesterone receptor (PR) protein and with overexpression/amplification of the human epidermal growth factor receptor 2 (HER2), termed hormone receptor-positive (HR+)/HER2+ BC, represents ∼10% of all BCs in the United States. HR+/HER2+ BC includes HER2+ BCs that are ER+, PR+, or both ER+ and PR+ (triple-positive BC). Although the current guideline-recommended treatment combination of anti-HER2 monoclonal antibodies plus chemotherapy is an effective first-line therapy for many patients with HER2+ advanced disease, intratumoral heterogeneity within the HR+/HER2+ subtype and differences between the HR+/HER2+ subtype and the HR-/HER2+ subtype suggest that other targeted combinations could be investigated in randomized clinical trials for patients with HR+/HER2+ BC. In addition, published data indicate that crosstalk between HRs and HER2 can lead to treatment resistance. Dual HR and HER2 pathway targeting has been shown to be a rational approach to effective and well-tolerated therapy for patients with tumors driven by HER2 and HR, as it may prevent development of resistance by blocking receptor pathway crosstalk. However, clinical trial data for such approaches are limited. Treatments to attenuate other signaling pathways involved in receptor crosstalk are also under investigation for inclusion in dual receptor targeting regimens. These include cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, based on the rationale that association of CDK4/6 with cyclin D1 may play a role in resistance to HER2-directed therapies, and others such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway inhibitors. Herein, we will review the scientific and clinical rationale for combined receptor blockade targeting HER2 and ER for patients with advanced-stage HR+/HER2+ disease.

Significance of differential expression of OLFM4 in the development of endometrial adenocarcinoma.

The incidence of endometrial adenocarcinoma (EA) has increased worldwide in recent years due to the widespread use of estrogen therapy and the overall increase in life expectancy. However, we know of no sensitive molecular index that can be used to predict the onset of EA, evaluate the therapeutic effects of treatment agents, or provide prognostic benefit in post-treatment follow-up. To explore the correlation between human olfactomedin 4 (OLFM4) and the clinicopathologic parameters of EA, and to determine the precise involvement of OLFM4 as a related factor in the occurrence and development of EA. We enrolled 61 gynecologic patients for a retrospective study at the Tai'an Central Hospital of Shandong Province from January 1, 2016, to June 30, 2022. We determined the expression levels of estrogen receptor α (ERα), progesterone receptor (PR), and OLFM4 proteins in endometrial tissue with the immunohistochemical S-P staining method, and analyzed the correlations among ERα, PR, and OLFM4 protein expression levels and with the pathologic stage, histologic grade, myometrial invasiveness, and lymphatic metastasis of EA. The expression levels of OLFM4 in EA were higher than in normal endometrium (P = .036). The expression level of OLFM4 protein in stage II-III patients was higher than that in stage I patients (P = .034), and the expression levels of ERα and PR proteins in EA were lower than those in normal endometrial tissue (P = .014 and P = .0005). While we observed no correlation in endometrial tissues of disparate pathologic types between OLFM4 and the expression levels of ERα and PR proteins, we noted a positive correlation between the expression levels of ERα and PR protein. The expression level of OLFM4 protein increased with the malignant degree of endometrial lesions and OLFM4 protein expression was related to the FIGO stage of EA. And OLFM4 protein can be used as 1 of the potential diagnostic factors for endometrial lesions, which is worthy of further study.

Kelulut Honey Regulates Sex Steroid Receptors in a Polycystic Ovary Syndrome Rat Model

Reproductive and metabolic anomalies in polycystic ovary syndrome (PCOS) have been associated with the dysregulation of sex steroid receptors. Kelulut honey (KH) has been shown to be beneficial in PCOS-induced rats by regulating folliculogenesis and the oestrus cycle. However, no study has been conducted to evaluate KH's effect on sex steroid receptors in PCOS. Therefore, the current study examined the effects of KH, metformin, or clomiphene alone and in combination on the mRNA expression and protein distribution of androgen receptor (AR), oestrogen receptor α (ERα), oestrogen receptor β (ERβ), and progesterone receptor (PR) in PCOS-induced rats. The study used female Sprague-Dawley rats, which were treated orally with 1 mg/kg/day of letrozole for 21 days to develop PCOS. PCOS-induced rats were then divided and treated orally for 35 days with KH, metformin, clomiphene, KH + metformin, KH+ clomiphene and distilled water. In this study, we observed aberrant AR, ERα, ERβ and PR expression in PCOS-induced rats compared with the normal control rats. The effects of KH treatment were comparable with clomiphene and metformin in normalizing the expression of AR, ERα, and ERβ mRNA. However, KH, clomiphene and metformin did not affect PR mRNA expression and protein distribution. Hence, this study confirms the aberrant expression of sex steroid receptors in PCOS and demonstrates that KH treatment could normalise the sex steroid receptors profile. The findings provide a basis for future clinical trials to utilize KH as a regulator of sex steroid receptors in patients with PCOS.

Postnatal exposure to a glyphosate-based herbicide interferes with the development and growth of the mammary gland of pre-pubertal Ewe lambs

The aim of the present study was to evaluate whether early postnatal exposure to a glyphosate-based herbicide (GBH) alters pre-pubertal mammary development in Friesian lambs. To this end, from postnatal day 1–14, ewe lambs were exposed subcutaneously or orally to GBH (2 mg/kg bw/day) or vehicle (control) and mammary gland biopsies were obtained at 45 days of age. GBH-exposed lambs exhibited larger mammary ducts and less area occupied by terminal duct lobular units than controls, accompanied by an increase in the area of adipocytes in the mammary stroma. Lambs subcutaneously exposed to GBH showed increased protein expression of estrogen receptor alpha; however, both GBH-exposed groups had decreased mRNA expression of this receptor. Control lambs showed nuclear progesterone receptor (PR) protein expression, whereas GBH-exposed animals showed cytoplasmic PR expression; both GBH-exposed groups exhibited decreased mRNA expression of PR. GBH-exposed lambs also had decreased epithelial cell proliferation. Regarding insulin-like growth factors, both groups showed similar IGF-1 mRNA and protein expression but decreased expression of its receptor, and increased IGFBP5 expression. In addition, phosphorylated AKT was only observed in the mammary gland of control lambs. Our results show that early postnatal exposure to GBH, regardless of the exposure route, affects the IGF-1 system and the AKT/protein kinase B pathway, interfering with steroid hormone receptor expression and cell proliferation. This consequently modifies the growth and development of the pre-pubertal mammary gland of Frisian lambs.

OR16-2 Steroid Receptor Co-Activator Complexes Regulate Metabolic PFKFB Enzymes to Drive Therapy Resistant ER+ Breast Cancer

Abstract Recurrence of metastatic breast cancer stemming from acquired endocrine and chemotherapy resistance remains a health burden for women with luminal (ER+) breast cancer. ER+ tumor cells can remain viable but quiescent for years to decades. Contributing factors to metastatic spread include the survival and expansion of breast cancer stem cells (CSCs). Breast CSCs are poorly proliferative and frequently exist as a minority population in recurrent tumors. Our objective is to define novel signaling pathways that govern therapy resistance in ER+ breast cancer. We previously showed that cytoplasmic complexes composed of steroid receptor (SR) co-activators, PELP1 and SRC-3, modulate breast CSC expansion through upregulation of the HIF-activated metabolic target genes PFKFB3 and PFKFB4. PELP1 interacts with PFKFB proteins, and inhibition of PFKFB3 and PFKFB4 kinase activity blocks PELP1-induced tumorspheres and protein-protein interactions with SRC-3. PFKFB inhibitors in combination with ER targeted therapies blocked proliferation and tumorsphere formation in multiple models of advanced breast cancer, including paclitaxel (TaxR) and tamoxifen (TamR) resistant models and ER+ patient-derived organoids (PDxO). Chemotherapy and endocrine therapy resistant models contained increased levels of cytoplasmic PELP1, PELP1/SRC-3 complexes, and phenocopied PELP1/SRC-3/PFKFB biology and CSC behavior. To better understand CSC-mediated pathways in the context of therapy resistance, we performed RNA-seq on 3D-cultured TaxR tumorspheres to enrich for CSCs. Pathway analysis revealed that TaxR tumorspheres upregulate stem (Sox2-Oct4-Nanog), HIF, and progesterone mediated pathways. Progesterone receptor (PR) is a known contributor to CSC populations, and we observed increased PR mRNA and protein expression in TaxR cells grown as tumorspheres. Additionally, in vivo emergence of circulating tumor cell (CTC) populations was observed in ER+ TaxR mammary intraductal (MIND) xenografts. Together, our data suggest that PELP1, SRC-3, and PFKFBs cooperate to drive ER+ tumor cells that include CSCs and CTCs. Our findings are applicable to therapy resistant models, indicating that SR co-activator complexes are a key mediator of resistance in ER+ breast cancer and may cooperate with PR to promote therapy resistant CSCs. Identifying non-ER pharmacological targets offers a useful approach to blocking metastatic escape from standard of care ER/estrogen (E2)-targeted strategies to overcome endocrine and chemotherapy resistance in ER+ breast cancer. Presentation: Sunday, June 12, 2022 11:15 a.m. - 11:30 a.m.