Alteration of E-cadherin, alpha- and beta-catenin mRNA expression in human uterine endometrium during the menstrual cycle

When the Embryo Meets the Endometrium: Identifying the Features Required for Successful Embryo Implantation

Evaluation of the optimal number of embryos, their quality, and the precise timing for transfer are critical determinants in reproductive success, although still remaining one of the main challenges in assisted reproduction technologies (ART). Indeed, the success of in vitro fertilization (IVF) treatments relies on a multitude of events and factors involving both the endometrium and the embryo. Despite concerted efforts on both fronts, the overall success rates of IVF techniques continue to range between 25% and 30%. The role of the endometrium in implantation has been recently recognized, leading to the hypothesis that both the "soil" and the "seed" play a central role in a successful pregnancy. In this respect, identification of the molecular signature of endometrial receptivity together with the selection of the best embryo for transfer become crucial in ART. Currently, efforts have been made to develop accurate, predictive, and personalized tests to identify the window of implantation and the best quality embryo. However, the value of these tests is still debated, as conflicting results are reported in the literature. The purpose of this review is to summarize and critically report the available criteria to optimize the success of embryo transfer and to better understand current limitations and potential areas for improvement.

Exosomal miR-205-5p Improves Endometrial Receptivity by Upregulating E-Cadherin Expression through ZEB1 Inhibition

Endometrial receptivity is a complex process that prepares the uterine endometrium for embryo implantation; insufficient endometrial receptivity is one of the causes of implantation failure. Here, we analyzed the microRNA expression profiles of exosomes derived from both receptive (RL95-2) and non-receptive (AN3-CA) endometrial epithelial cell (EEC) lines to identify exosomal miRNAs closely linked to endometrial receptivity. Among the 466 differentially expressed miRNAs, miR-205-5p was the most highly expressed in exosomes secreted from receptive RL95-2 cells. miR-205-5p, enriched at the adhesive junction, was closely related to endometrial receptivity. ZEB1, a transcriptional repressor of E-cadherin associated with endometrial receptivity, was identified as a direct target of miR-205-5p. miR-205-5p expression was significantly lower in the endometrial tissues of infertile women than in that of non-infertile women. In vivo, miR-205-5p expression was upregulated in the post-ovulatory phase, and its inhibitor reduced embryo implantation. Furthermore, administration of genetically modified exosomes overexpressing miR-205-5p mimics upregulated E-cadherin expression by targeting ZEB1 and improved spheroid attachment of non-receptive AN3-CA cells. These results suggest that the miR-205-5p/ZEB1/E-cadherin axis plays an important role in regulating endometrial receptivity. Thus, the use of exosomes harboring miR-205-5p mimics can be considered a potential therapeutic approach for improving embryo implantation.

The immunolocalization of cadherins and beta-catenin in the cervix and vagina of cycling cows

The adherens junctions (AJs) maintain the epithelial cell layers' structural integrity and barrier function. AJs also play a vital role in various biological and pathological processes. AJs perform these functions through the cadherin-catenin adhesion complex. This study investigated the presence, cell-specific localization, and temporal distribution of AJ components such as classical type I cadherins and beta-catenin in the cow cervix and vagina during the estrous cycle. Immunohistochemistry and Western blot analysis results demonstrated that beta-catenin and epithelial (E)-, neural (N)-, and placental (P)-cadherins are expressed in the cow cervix and vagina during the estrous cycle. These adhesion molecules were localized in the membrane and cytoplasm of the ciliated and non-ciliated cervical cells and the stratified vaginal epithelial cells. Positive immunostaining for P-, N-cadherin, and beta-catenin was also observed in the vascular endothelial cells of the cervical and vaginal stroma. Quantitative immunohistochemistry examinations revealed that in the cervical and vaginal epithelia, P-cadherin's optical density values (ODv) were the highest; in contrast, the N-cadherin ODv were the lowest. The ODv of P-cadherin and beta-catenin in the cervical epithelium and E-cadherin in the vagina were significantly higher in the luteal phase versus the follicular phase of the estrous cycle. Furthermore, the ODv of P-cadherin, N-cadherin, and beta-catenin in the cervix's central and peripheral epithelial regions were different during the estrous cycle. These findings indicate that classical cadherins and beta-catenin in the cervix and vagina exhibit cell- and tissue-specific expression patterns under the influence of estrogen and progesterone hormones during the estrous cycle.

Current Biomarkers for Endometrial Receptivity

Implantation and the continuation of pregnancy occur through a complicated and sophisticated dialogue, called “cross-talk,” which starts between the embryo and the endometrium in the early stages of oocyte maturation. This dialogue provides synchronization of the journey of the embryo to be implanted with the receptive endometrium. Understanding the activity and function of the hormones and factors involved in this dialogue will provide an understanding of endometrial receptivity, which plays a key role in implantation, and the determination of biomarkers specific for this period. As a result of the development of omics technology, it has become possible to identify biomarkers specific to endometrial receptivity by performing genomic, proteomic, and lipidomic analyses of these hormones and factors. The determination of these biomarkers, their optimization, and making them usable in the clinic will allow increased success in ART.

High-Throughput In Vitro Screening Identified Nemadipine as a Novel Suppressor of Embryo Implantation

Current contraceptive methods interfere with folliculogenesis, fertilization, and embryo implantation by physical or hormonal approaches. Although hormonal contraceptive pills are effective in regulating egg formation, they are less effective in preventing embryo implantation. To explore the use of non-hormonal compounds that suppress embryo implantation, we established a high-throughput spheroid-endometrial epithelial cell co-culture assay to screen the Library of Pharmacologically Active Compounds (LOPAC) for compounds that affect trophoblastic spheroid (blastocyst surrogate) attachment onto endometrial epithelial Ishikawa cells. We identified 174 out of 1280 LOPAC that significantly suppressed BeWo spheroid attachment onto endometrial Ishikawa cells. Among the top 20 compounds, we found the one with the lowest cytotoxicity in Ishikawa cells, P11B5, which was later identified as Nemadipine-A. Nemadipine-A at 10 µM also suppressed BeWo spheroid attachment onto endometrial epithelial RL95-2 cells and primary human endometrial epithelial cells (hEECs) isolated from LH +7/8-day endometrial biopsies. Mice at 1.5 days post coitum (dpc) treated with a transcervical injection of 100 µg/kg Nemadipine-A or 500 µg/kg PRI-724 (control, Wnt-inhibitor), but not 10 µg/kg Nemadipine-A, suppressed embryo implantation compared with controls. The transcript expressions of endometrial receptivity markers, integrin αV (ITGAV) and mucin 1 (MUC1), but not β-catenin (CTNNB1), were significantly decreased at 2.5 dpc in the uterus of treated mice compared with controls. The reduction of embryo implantation by Nemadipine-A was likely mediated through suppressing endometrial receptivity molecules ITGAV and MUC1. Nemadipine-A is a potential novel non-hormonal compound for contraception.

Modulation of E-Cadherin and N-Cadherin by ovarian steroids and embryonic stimuli

Endometrium is a dynamic tissue that undergoes extensive remodelling to attain a receptive state which is further modulated in presence of an embryo for successful initiation of pregnancy. Cadherins are the proteins of the junctional complex of which E-cadherin (E-Cad) is crucial for maintaining epithelial cell state and integrity of the epithelial barrier; gain of N-cadherin (N-Cad) in epithelial cells leads to epithelial to mesenchymal transition (EMT). In the present study, we investigated the expression of E-Cad and N-Cad in the mouse endometrial luminal epithelium and its modulation by estrogen, progesterone, and embryonic stimuli. We observed that E-Cad is diffusely expressed in the luminal epithelium of mouse endometrium during the estrus stage and upon estrogen treatment. It is apico-laterally and basolaterally sorted at the diestrus stage and in response to the combined treatment of estrogen and progesterone. In 3D spheroids of human endometrial epithelial cells, combined treatment with estrogen and progesterone led to lateral sorting of E-Cad without any effects on its mRNA levels. at the time of embryo implantation, there is loss of E-Cad along with the gain of N-Cad and SNAIL expression suggestive of EMT in the luminal epithelium. This EMT is possibly driven by embryonic stimuli as treatment with estrogen and progesterone did not lead to the gain of N-Cad expression in the mouse endometrium in vivo or in human endometrial epithelial cells in vitro. In conclusion, the present study demonstrates that steroid hormones directly affect E-Cad sorting in the endometrial epithelium which undergo EMT in response to embryonic stimuli.

Malignant Transformation and Associated Biomarkers of Ovarian Endometriosis: A Narrative Review

This review focuses on pathogenesis of endometriosis, its possible biomarkers and role in endometriosis-associated ovarian cancer. We analyzed various databases to obtain new insights, theories, and biomarkers associated with endometriosis. There are several theories of endometriosis development and biomarker changes including atypical forms. A number of studies have attempted to establish specific, reliable biomarkers to help diagnose endometriosis and endometriosis-associated diseases on the basis of different pathogenetic pathways. Nevertheless, despite intensive research extending even to the molecular level, the origin, natural history, malignant transformation, and laboratory management of endometriosis and related diseases are not yet clearly defined. Therefore, early laboratory diagnoses of endometriosis, its atypical form, and endometriosis-associated ovarian tumors are important problems that require further study in the context of advanced therapeutic strategies to provide maximal health benefits to patients.

Changes in the expression and distribution of junction and polarity proteins in the porcine endometrium during early pregnancy period

The maternal endometrium undergoes transformations during early pregnancy period to regulate the paracellular permeability across the epithelium and to enable adhesion between the trophoblast and endometrial epithelial cells. These transformations, under the influence of ovarian hormones, are associated with a partial loss in polarity of epithelial cell that is regulated by tight junctions (TJ), adherens junctions (AJ) and associated polarity protein complexes. This study examined the change in expression and distribution of proteins associated with TJs, AJs and apical partition defective (PAR) complex in porcine endometrium on Days 10, 13 and 16 of estrous cycle and pregnancy. Moreover, effect of hormones, progesterone (P4) and 17-β estradiol (E₂) on polar phenotype of endometrial epithelial cells was also investigated in vitro. There was pregnancy induced increase in gene and protein expression of TJ associated claudin-1 (CLDN1) on Day 13 of pregnancy as compared to corresponding day of estrous cycle and a decrease in TJ protein, zona occludens-1 (ZO-1) and PAR complex associated PAR6 expression levels on Day 16 of pregnancy (P < 0.05). Immunofluorescence studies revealed that on Days 10 and 13, TJ proteins occludin (OCLN) and ZO-1were primarily present in the apical region of lateral epithelial membrane. On Day 16 of pregnancy, whereas, OCLN redistributed into cytoplasm, ZO-1 decreased apically but was found to localize in the basal epithelium. The AJ proteins cadherin and β-catenin were located at the apical epithelium on Day 10 of estrous cycle and pregnancy and Day 13 of estrous cycle. On Days 13 and 16 of pregnancy both proteins were expressed in the lateral membrane and co-localization between these proteins was observed on Day 16. On Day 10, PAR complex proteins PAR3, cell division control protein 42 (CDC42) and atypical protein kinase C (aPKC) ζ were observed in apical epithelium and in lateral membrane and CDC42 was also present in the cytoplasm of epithelium. Pregnancy induced redistribution of aPKCζ to cytoplasm and CDC42 to apical surface of luminal epithelium was observed on Days 13 and 16. The in vitro P4 and E₂ treatment of epithelial cells mimicked in vivo results. These results indicate that P4 and E₂ regulate alterations in epithelium that may facilitate embryo implantation and given the role of cadherin, catenin and CDC42 in embryo invasion, change in distribution of these proteins may limit the invasiveness of porcine conceptuses into the stroma.

Endometrial Expression of Homeobox Genes and Cell Adhesion Molecules in Infertile Women With Intramural Fibroids During Window of Implantation

This study was designed to examine the expression and cellular distribution of homeobox ( HOX) genes ( HOXA10 and HOXA11) and cell adhesion molecules (E-cadherin, N-cadherin, and β-catenin) during the window of implantation in infertile women with noncavity-distorting intramural (IM) fibroids (n = 18) and in fertile controls (n = 12). Quantitative real-time polymerase chain reaction and immunohistochemistry were used to evaluate the messenger RNA (mRNA) levels and protein expression, respectively. When compared to fertile controls, reduced HOXA10 and HOXA11 transcript and protein levels were observed in infertile women. However, changes only in the expression of HOXA10 mRNA (-1.72-fold; P = .03) and stromal protein ( P = .001) were statistically significant. Significantly lower E-cadherin mRNA (-10.97-fold; P = .02) and protein levels were seen in infertile patients. E-cadherin immunostaining was significantly reduced both in the luminal ( P = .048) and in the glandular ( P = .014) epithelium of endometrium from infertile patients when compared to controls. No significant change was observed either in the mRNA levels or in the immunoexpression of N-cadherin and β-catenin. However, a trend toward lower N-cadherin expression in the luminal epithelium ( P = .054) and decreased β-catenin expression in the glandular epithelium ( P = .070) was observed in infertile patients. The present findings suggest that altered endometrial HOXA10 and E-cadherin mRNA and protein expression observed in infertile women with IM fibroids during the mid-secretory phase might impair endometrial receptivity leading to infertility in these patients.

Endometrial Stromal Decidualization Responds Reversibly to Hormone Stimulation and Withdrawal

Human endometrial stromal decidualization is required for embryo receptivity, angiogenesis, and placentation. Previous studies from our laboratories established that connexin (Cx)-43 critically regulates endometrial stromal cell (ESC) differentiation, whereas gap junction blockade prevents it. The current study evaluated the plasticity of ESC morphology and Cx43 expression, as well as other biochemical markers of cell differentiation, in response to decidualizing hormones. Primary human ESC cultures were exposed to 10 nM estradiol, 100 nM progesterone, and 0.5 mM cAMP for up to 14 days, followed by hormone withdrawal for 14 days, mimicking a biphasic ovulatory cycle. Reversible differentiation was documented by characteristic changes in cell shape. Cx43 was reversibly up- and down-regulated after the estradiol, progesterone, and cAMP treatment and withdrawal, respectively, paralleled by fluctuations in prolactin, vascular endothelial growth factor, IL-11, and glycodelin secretion. Markers of mesenchymal-epithelial transition (MET), and its counterpart epithelial-mesenchymal transition, followed reciprocal patterns corresponding to the morphological changes. Incubation in the presence of 18α-glycyrrhetinic acid, an inhibitor of gap junctions, partially reversed the expression of decidualization and MET markers. In the absence of hormones, Cx43 overexpression promoted increases in vascular endothelial growth factor and IL-11 secretion, up-regulated MET markers, and reduced N-cadherin, an epithelial-mesenchymal transition marker. The combined results support the hypothesis that Cx43-containing gap junctions and endocrine factors cooperate to regulate selected biomarkers of stromal decidualization and MET and suggest roles for both phenomena in endometrial preparation for embryonic receptivity.

Participation of WNT and β-Catenin in Physiological and Pathological Endometrial Changes: Association with Angiogenesis

WNT proteins are involved in embryonic development, sex determination, stem cell recruitment, angiogenesis, and cancer. They take part in morphological changes in the endometrium during development, regulate processes of endometrial proliferation and differentiation. This review presents current knowledge about implication of WNT proteins and β-catenin in physiological endometrial functions as well as their involvement in uterine carcinogenesis. Influence of WNT proteins on the formation of blood vessel, taking place both under healthy and pathological conditions, is also considered. Participation of WNT proteins, β-catenin, and inhibitors and inducers of WNT signaling in the process of endometrial angiogenesis is largely unknown. Thus, confirmation of their local and systemic participation in the process of endometrial angiogenesis may in the long term help to establish new diagnostic and therapeutic approaches in conditions associated with the pathology of the female reproductive system.

Molecular aspects of development and regulation of endometriosis

Endometriosis is a common and painful condition affecting women of reproductive age. While the underlying pathophysiology is still largely unknown, much advancement has been made in understanding the progression of the disease. In recent years, a great deal of research has focused on non-invasive diagnostic tools, such as biomarkers, as well as identification of potential therapeutic targets. In this article, we will review the etiology and cellular mechanisms associated with endometriosis as well as the current diagnostic tools and therapies. We will then discuss the more recent genomic and proteomic studies and how these data may guide development of novel diagnostics and therapeutics. The current diagnostic tools are invasive and current therapies primarily treat the symptoms of endometriosis. Optimally, the advancement of "-omic" data will facilitate the development of non-invasive diagnostic biomarkers as well as therapeutics that target the pathophysiology of the disease and halt, or even reverse, progression. However, the amount of data generated by these types of studies is vast and bioinformatics analysis, such as we present here, will be critical to identification of appropriate targets for further study.

Expression of P-cadherin (cadherin-3) and E-selectin in the villous trophoblast of first trimester human placenta

OBJECTIVE

Although trophoblastic invasion has a critical role in human placental development, very little is known about them. The aim of the present study was to localise the expression of P-cadherin (cadherin-3) and E-selectin in first trimester placenta.

MATERIAL AND METHODS

This study was conducted on 140 patients who had applied to Gülhane Military Medical Academy, Haydarpaşa Education Hospital, Department of Obstetrics and Gynaecology between 2005 and 2006. The patients were divided into three groups: ectopic pregnancy group (Group 1), spontaneous abortion group (group 2) and curettage group (group 3 and/or control group). Patients with a history of systemic diseases (such as thrombophilia), a disease or anatomical diagnosis that may cause recurrent abortion or an aetiological factor for ectopic pregnancy were excluded from the study. Paraffin blocks were stained with E-selectin and P-cadherin in accordance with the procedure. Demographic characteristics of patients (patient age, gravida, parity, number of previous abortions, and last menstrual period) and staining intensities were compared using Analysis of Variance (ANOVA) among groups.

RESULTS

According to the average scale score of P-cadherin staining of cells, the three groups were statistically different from each other (p=0.0001). This difference stems from statistically significantly lower scores in the spontaneous abortion group than in both the ectopic pregnancy group (p<0.001) and the control group (p<0.001). E-selectin immunostaining showed no positive staining in the groups.

CONCLUSION

In placental trophoblasts, decreased P-cadherin immunoreactivity plays a role in the aetiopathogenesis of spontaneous abortion.

Characterization of foamy epithelial surface cells in the canine endometrium

In mature bitches, endometrial epithelial surface cells modify function and corresponding morphology during the oestrous cycle. During late metoestrous, endometrial epithelial surface cells frequently accumulate fat and thereby adopt a foamy morphology. This cyclic appearance of foamy endometrial epithelial cells (fEECs) seems to be physiological in the dog, whereas in other species, it indicates pathological changes. Function of these fEECs has not been identified until now. Therefore, the aim of the study was to characterize the fEECs by means of transmission electron microscopy and immunohistochemistry. Different manifestations of fEECs were observed and analysed with regard to proliferative activity and presence of different epithelial adhesion molecules including PLEKHA7, β-catenin and E-cadherin. PLEKHA7 was restricted to the apical regions of the fEECs, whereas E-cadherin and β-catenin were demonstrated basolateral. The immunohistochemical detection of steroid hormone receptors demonstrated the responsiveness of the fEECs to steroid hormones. Intense progesterone receptor expression was observed in the fEECs indicating a high responsiveness to this hormone. Considering a potential function of the fEECs, we hypothesized that leptin, a hormone produced by other lipid-accumulating cells and described to be involved in reproduction, in particular during implantation, might also originate from the fEECs which was confirmed by immunohistochemical methods. Moreover, leptin receptor was found in fEECs indicating the fEECs as both, source and target for leptin. Therefore, we conclude that fEECs in the canine uterus have a potential role in early pregnancy events and that the different observed manifestations might simply reflect the variations of signs of pseudopregnancy among bitches.

Sex steroids regulate epithelial-stromal cell cross talk and trophoblast attachment invasion in a three-dimensional human endometrial culture system

Human embryo implantation involves a complex network of molecular signaling that is modulated by endocrine and paracrine pathways. Here, we performed studies using a unique and recently developed three-dimensional (3D) implantation model, characterized by an endometrium-like 3D culture system and Jar cell-derived spheroids mimicking the embryo/trophoblast. The aims were to investigate the effects of 17β estradiol (E2) and medroxyprogesterone acetate (MPA) on (1) the interaction between epithelial and stromal cells, and (2) the attachment and invasion of trophoblast cells. We observed that epithelial and stromal cells in the 3D culture were ERα⁺, ERβ⁺, and PR⁺. Decidualization was confirmed by enhanced prolactin gene expression on day 7 of E2 plus MPA treatment. An effect of epithelial cells on the decidualization of stromal cells was indicated by significantly higher levels of prolactin mRNA expression in the 3D culture compared to stromal cells grown within the fibrin-agarose gel matrix. On the other hand, the relative gene expressions of E-cadherin and IL-1β in epithelial cells of the 3D culture under decidualization conditions significantly differed from those in epithelial cells grown over the fibrin-agarose gel matrix without stromal cells, pointing to regulation of epithelial cells by the stroma. The attachment rate of Jar spheroids to the 3D was significantly increased by E2 plus MPA treatment. Analyses of Z-stack confocal and stained optic microscopic images demonstrated that Jar spheroids breached the epithelial cell monolayer, invaded, and were embedded into the 3D matrix in response to decidualization signals. In summary, the newly bioengineered system provides a unique model for studying interactions between the different endometrial cell compartments, via soluble-paracrine signals as well as cell-to-cell interactions, and is a useful tool to study early embryonic implantation events.

Endometrium in women with polycystic ovary syndrome during the window of implantation

The human endometrium undergoes to a complex series of proliferative and secretory changes in each menstrual cycle and displays only a short period of receptivity, known as the "window of implantation", necessary for the implantation of the blastocyst in the uterus. The implantation process occurs in a sequential manner, leading to the establishment of pregnancy. Morphofunctional changes during this period may prevent or hinder the implantation. For this reason, the study of the endometrium at this stage is important for the improvement of therapies that may interfere with the mechanisms involved in maternal-embryonic interaction. Several gynecological disorders, including polycystic ovary syndrome (PCOS), are associated with decreased fertility and uterine receptivity. In spite of recent advances in assisted reproduction techniques, allowing the selection of high quality embryos, the implantation rate remains low and has not increased enough in recent decades. This article aims at reviewing the endometrial aspects of the "window of implantation" in women with polycystic ovary syndrome, focusing mainly on adhesion molecules. For that purpose, we analyzed 105 articles published in journals indexed in PubMed in the last 50 years (up to May 2011). In conclusion, the endometrial receptivity seems to be the major limiting factor for the establishment of pregnancy in a large number of gynecological diseases, including PCOS, and treatment to improve implantation rates is likely to be taken towards this direction.

Expression and hormonal regulation of E-cadherin in canine uterus during early pregnancy

E-cadherin, a Ca(2+)-dependent cell adhesion molecule, is necessary for endometrial receptivity to blastocyst implantation. The aim of this study was to investigate the differential expression of E-cadherin in canine uterus during early pregnancy and its regulation under different conditions by in situ hybridization. E-cadherin mRNA expression was at a low level in the glandular epithelium on days 6, 12 and 17 of pregnancy. On days 20 and 23 of pregnancy, E-cadherin mRNA was highly expressed in the glandular epithelium surrounding the embryo, but not in the luminal epithelium and declined in villi and placenta on day 28 of pregnancy. During oestrous cycle, a moderate level of E-cadherin mRNA expression was found in the luminal and glandular epithelium of canine uteri at oestrus stage. The same expression was also found at anoestrus stage. Progesterone slightly induced the expression of E-cadherin mRNA in the luminal and glandular epithelium of ovariectomized canine uterus. These results suggest that E-cadherin expression is closely related to canine implantation and can be up-regulated by progesterone.

MicroRNA array and microarray evaluation of endometrial receptivity in patients with high serum progesterone levels on the day of hCG administration

BACKGROUND

To determine the effect of higher progesterone (P) level on endometrial receptivity.

METHODS

This was a prospective analysis conducted in the Reproductive Medical Center of Peking University Third Hospital. All patients received IVF treatment and canceled embryo transfer in the same cycle and were divided into group 1 (normal P; 7 patients) and group 2 (elevated P; 12 patients). Endometrial biopsies were performed 6 days after oocyte retrieval. The global miRNA and mRNA gene expressions in endometrial biopsies were investigated with a V4.0 miRNA probe and 22 K Human Genome Array. Fold ratios were derived to compare gene regulation between the groups. Spp1 and Ang gene expression was selected to verify the array results by RT-PCR and the protein expression of osteopontin and VEGF was determined using an immunohistochemical method.

RESULTS

There were 4 miRNA (all down-regulated) and 22 mRNA (13 up-regulated and 9 down-regulated) exhibiting differential expression between the groups on the microRNA and microarray chips. miRNA-451, Spp1, and Ang expression in RT-PCR verified the array results. Osteopontin and VEGF were also shown to have positive expression in the endometrium.

CONCLUSIONS

Data from microRNA and microarray analysis suggests dissimilar endometrial receptivity in patients with high P levels on the day of hCG, and elevated osteopontin and decreased VEGF had poor pregnancy rates.

Impaired down-regulation of E-cadherin and beta-catenin protein expression in endometrial epithelial cells in the mid-secretory endometrium of infertile patients with endometriosis

CONTEXT

Only a few, small, human studies on E-cadherin and beta-catenin expression in normal cycling human endometrium have been reported. It remains unclear whether expression of these molecules might be altered in the endometrium of infertile patients with endometriosis.

OBJECTIVES

The aim of the present study was to investigate E-cadherin and beta-catenin expression in the endometrium of infertile patients with endometriosis, those with uterine fibromas, and patients with unexplained infertility.

DESIGN

Expression levels of E-cadherin and beta-catenin mRNA and/or protein in the endometrium of infertile patients with endometriosis (n = 151), those with uterine fibromas (n = 41), patients with unexplained infertility (n = 9), as well as healthy fertile controls (n = 57) were measured. This study utilized laser capture microdissection, real-time RT-PCR, and immunohistochemistry.

RESULTS

No significant differences in E-cadherin or beta-catenin mRNA expression in microdissected epithelial cells were observed among the different groups throughout the menstrual cycle. However, very low or no protein expression of E-cadherin, total beta-catenin, or dephosphorylated beta-catenin in luminal and glandular epithelial cells was detected in the mid-secretory endometrium of healthy fertile controls. E-cadherin, total beta-catenin, and dephosphorylated beta-catenin protein expression in the mid-secretory endometrium of infertile patients with endometriosis or unexplained infertility was significantly higher compared to that of healthy fertile controls in both luminal and glandular epithelial cells.

CONCLUSIONS

These findings suggest that impaired down-regulation of E-cadherin and beta-catenin protein expression, along with Wnt/beta-catenin signaling pathway activation during the window of implantation, might be one of the potential molecular mechanisms of infertility in patients with endometriosis.

Expression of E- and N-cadherin and CD44 in endometrium and hydrosalpinges from infertile women

In this prospective comparative study, compared with fertile control subjects (n = 12), infertile patients with hydrosalpinx (n = 18) had lower E-cadherin and a trend toward decreased N-cadherin H-scores in the endometrium (3.6 ± 0.6 vs. 2.4 ± 0.8 and 0.57 ± 1.0 vs. 0.52 ± 0.5, respectively). In hydrosalpinx, epithelial N-cadherin expression was discontinuous and disappeared in atrophic patches.

Adhesion molecules in endometrial epithelium: tissue integrity and embryo implantation

Cell adhesion in endometrial epithelium is regulated to maintain the continuity and protectiveness of the luminal covering cell layer while permitting interstitial implantation of the embryo during a restricted period of about 4 days. Many apparently normal embryos fail to implant, and epithelial-embryo adhesion remains a poorly understood phenomenon. After menstruation, epithelial regeneration occurs by epiboly from the basal residues of glands, an activity that requires migration on extracellular matrix as well as cell-cell cohesion. Here we review current knowledge of adhesion molecules in the epithelium.

Epigenetic regulation of E-cadherin controls endometrial receptivity

Key to the success of human reproduction is the capacity of an embryo to attach and implant into the endometrial wall after which a nutrient supply is established through placentation. Herein, we have examined the potential epigenetic regulation of uterine receptivity by use of the receptive RL95-2 and nonreceptive AN3-CA endometrial epithelial carcinoma cell lines. Using an in vitro model of embryo implantation, we demonstrate that inhibition of DNA methylation by 5'-aza-2'-deoxycytidine (AZA), resulted in the nonreceptive AN3-CA cell line becoming receptive to BeWo cell spheroid attachment. Examination of components of the adherens junction complex revealed that AZA specifically increased the expression of E-cadherin and plakoglobin at the mRNA and protein levels in AN3-CA cells, and E-cadherin protein expression was found to localize to sites of intercellular contact. Forced expression of E-cadherin in AN3-CA cells significantly enhanced receptivity. Small interfering RNA (siRNA)-mediated depletion of the individual DNA methyltransferase (DNMT) molecules did not induce E-cadherin expression in AN3-CA cells; however, concomitant siRNA-mediated depletion of both DNMT3A and DNMT3B induced the expression of E-cadherin. Furthermore, E-cadherin expression was significantly increased after the concomitant siRNA-mediated depletion of DNMT-1, -3A, and -3B in AN3-CA cells. Therefore, we have provided evidence that E-cadherin plays an important role in uterine receptivity and that E-cadherin expression is epigenetically regulated in AN3-CA cells, suppressed by the combined actions of DNMT-1, -3A, and -3B.

Microarray evaluation of endometrial receptivity in Chinese women with polycystic ovary syndrome

Patients with polycystic ovary syndrome (PCOS) have lower pregnancy and higher miscarriage rates, possibly due to decreased endometrial receptivity. In this study, endometrium was processed for RNA extraction and hybridization of chemically fragmented, biotinylated, complementary RNA on high-density oligonucleotide microarrays, and screened for 21,571 genes. Real-time polymerase chain reaction (PCR) was used to verify the result. Genes found to be down-regulated in the endometrium during the implantation window in PCOS patients included those whose activity was integral to membrane function, adhesion, invasive growth and the cytoskeleton. Among these genes, some have previously been associated with endometrial receptivity (by microarray research or other methods) and some have never previously been associated with endometrial receptivity. Using real-time PCR, expression of transmembrane 4 superfamily member 4 (TM4SF4) and matrix metalloproteinase 26 (MMP26) was found to be significantly decreased during the implantation window in patients with PCOS (P= 0.003). TM4SF4 has been demonstrated to be associated with adhesion; MMP26 has been shown to be related to degradation of extracellular matrix. It is suggested the down-regulated gene expression during the implantation window in patients with PCOS indicates differential gene expression in the endometrium between PCOS and normal women during the implantation window. This might affect endometrial receptivity.

Endometrial receptivity markers, the journey to successful embryo implantation

Human embryo implantation is a three-stage process (apposition, adhesion and invasion) involving synchronized crosstalk between a receptive endometrium and a functional blastocyst. This ovarian steroid-dependent phenomenon can only take place during the window of implantation, a self-limited period of endometrial receptivity spanning between days 20 and 24 of the menstrual cycle. Implantation involves a complex sequence of signalling events, consisting in the acquisition of adhesion ligands together with the loss of inhibitory components, which are crucial to the establishment of pregnancy. Histological evaluation, now considered to add little clinically significant information, should be replaced by functional assessment of endometrial receptivity. A large number of molecular mediators have been identified to date, including adhesion molecules, cytokines, growth factors, lipids and others. Thus, endometrial biopsy samples can be used to identify molecules associated with uterine receptivity to obtain a better insight into human implantation. In addition, development of functional in vitro systems to study embryo-uterine interactions will lead to better definition of the interactions existing between the molecules involved in this process. The purpose of this review was not only to describe the different players of the implantation process but also to try to portray the relationship between these factors and their timing in the process of uterine receptivity.

Trophoblast-uterine interactions at implantation

Implantation of the embryo in the uterus is a critical and complex event and its failure is widely considered an impediment to improved success in assisted reproduction. Depending on whether placentation is invasive or superficial (epitheliochorial), the embryo may interact transiently or undergo a prolonged adhesive interaction with the uterine epithelium. Numerous candidate interactions have been identified, and there is good progress on identifying gene networks required for early placentation. However no molecular mechanisms for the epithelial phase are yet firmly established in any species. It is noteworthy that gene ablation in mice has so far failed to identify obligatory initial molecular events.

Lithium treatment enhances estradiol-induced proliferation and hyperplasia formation in the uterus of mice

OBJECTIVES

It is suggested that the Wnt/beta-catenin pathway plays a role in the regulation of estrogen action in the uterus. However, this suggestion has not been proved. Lithium can mimic increased activity of the Wnt/beta-catenin pathway by blocking the activity of glycogen synthase kinase-3beta. There are no data on the effects of lithium on estrogen-dependent processes in the uterus. This work was therefore aimed to examine the action of lithium on proliferative and morphogenetic reactions in the uterus under short- and long-term estrogen treatments.

STUDY DESIGN

Ovariectomized mice received estradiol dipropionate (2 microg per 100g; s.c.) once a week or vehicle and drank tap water with 0.05% lithium chloride or plain tap water for 2 or 30 days.

RESULTS

In animals treated with estradiol and lithium for a month, the incidence of atypical endometrial hyperplasia was significantly higher. In animals treated with estradiol and lithium for 2 days or for a month, uterine mass, the number of mitotic cells and BrdU-labelled cells in luminal epithelium, glandular epithelium, stromal and myometrial cells was markedly greater, whereas the levels of estrogen receptors-alpha, beta-catenin and glycogen synthase kinase-3beta were markedly lower in all uterine compartments, than in those in mice received estradiol with no lithium to drink.

CONCLUSIONS

Lithium treatment results in an increase in estradiol-induced proliferative and morphogenetic changes in the uterus. This action of lithium is associated with decreased expression of estrogen receptors-alpha, beta-catenin and glycogen synthase kinase-3beta in the uterus.

Ligand activation of the androgen receptor downregulates E-cadherin-mediated cell adhesion and promotes apoptosis of prostatic cancer cells

Androgen independence is the major cause of endocrine therapy failure in advanced prostate cancer (PC). To examine the effects of human androgen receptor (AR) expression on growth of human PC cells, transfection of full-length AR cDNA in an androgen-insensitive human prostatic adenocarcinoma cell line (DU145) was performed. Transcriptional activity of AR was confirmed by the MMTV luciferase assay and AR expression was assessed by reverse transcriptase polymerase chain reaction, Western blotting, and immunocytochemistry. Two stable transfectant cell lines expressing functional AR were established and passaged over 60 times. Under standard culture conditions, AR expression in transfected cells was predominantly cytoplasmic. Exposure to dihydrotestosterone (DHT; 60 pM-10 nM) resulted in a rapid (maximal at 30 minutes) translocation of AR to the nucleus. Treatment with DHT (5 nM) caused a significant reduction in cell-cell adhesion and aggregation accompanied by a decrease in E-cadherin expression. This was associated with up to 40% inhibition of proliferation and approximately two-fold increase in apoptosis. These results suggest that gene transfer-mediated AR expression in DU145 cells confers sensitivity to DHT, modulates cell-cell adhesion through E-cadherin, and suppresses cell growth by inhibiting proliferation and promoting apoptosis. This provides amodelfor studies ofAR-regulated cell signalling and identification of novel androgen-regulated genes in PC.

Uterine response to estradiol under action of chorionic gonadotropin in mice

This work examined the effect of chorionic gonadotropin on proliferative and morphogenetic reactions in the uterus under short- and long-term estrogen treatments. Ovariectomized mice received a single injection with estradiol dipropionate (2 micro g per 100 g; subcutaneously, sc) or vehicle and injections with human chorionic gonadotropin (10 IU per 100 g; sc) or vehicle twice a day for 2 days. Other groups of animals received injections with estradiol once a week or vehicle and injections with chorionic gonadotropin or vehicle once a day for 30 days. The uteri were removed 48 h after the last estradiol or vehicle injection. In animals treated with estradiol and chorionic gonadotropin for a month, the incidence of atypical endometrial hyperplasia was significantly higher. In animals treated with estradiol and chorionic gonadotropin for 2 days or for a month, uterine mass was slightly increased, the number of mitotic cells and BrdU-labeled cells was greater in luminal epithelium, glandular epithelium, stromal and myometrial cells, whereas the expression of estrogen receptors-alpha was lower in all uterine compartments, than in control. In mice who received estradiol and chorionic gonadotropin for 2 days, levels of beta-catenin and glycogen synthase kinase-3beta in luminal and glandular epithelia were lower. In animals treated with estradiol and chorionic gonadotropin for a month, the level of beta-catenin was slightly higher, and the expression of glycogen synthase kinase-3beta was lower in luminal and glandular epithelia. Thus, chorionic gonadotropin exerts estradiol-induced proliferative and morphogenetic changes in the uterus. This action of chorionic gonadotropin is associated with decreased expression of estrogen receptors-alpha and with changes in expression of beta-catenin and glycogen synthase kinase-3beta in the uterus.

Expression of estrogen receptor-alpha, glucocorticoid receptor, beta-catenin and glycogen synthase kinase-3beta in the uterus of mice following long-term treatment with estrogen and glucocorticoid hormones

BACKGROUND

It has been shown that long-term glucocporticoid administration to chronically estradiol-treated mice decreases uterine weight, proliferation in all uterine tissues, the number of perpendicularly oriented mitoses in uterine epithelia and the incidence of atypical endometrial hyperplasia. However, mechanisms of chronic glucocorticoid action on estrogen-dependent processes in the uterus are unclear.

METHODS AND RESULTS

Results of present research showed that adding of glucocorticoid dexamethasone (in drinking water, 2mg/l) to estradiol-treated mice led to a decrease in the level of glucocorticoid receptor, to an increase in levels of estrogen receptor-alpha, beta-catenin and glycogen synthase kinase-3beta in uterine tissues of ovariectomized mice at 30, 60 and 90 days of the treatment. When vehicle was used instead estradiol, dexamethasone did not produce detectable changes in all parameters tested at all periods of observation.

CONCLUSION

Results allow to conclude that estrogen and glucocorticoid receptors, beta-catenin and glycogen synthase kinase-3beta are involved in estrogen-dependent changes in uterine morphology and hyperplasia formation.

Promoter hypermethylation as an epigenetic component in Type I and Type II endometrial cancers

Epigenetic mechanisms that result in aberrant gene expression are a prominent feature of many cancer types. One main epigenetic mechanism for gene silencing involves promoter hypermethylation. Type I and type II endometrial cancers exhibit differing clinical, histologic, and molecular genetic characteristics. We hypothesize that these differences also extend to epigenetic phenomena. Promoter methylation analysis of 11 genes in a panel of endometrial cancers supports this hypothesis. These initial data indicate that promoter hypermethylation events occur frequently in type 1 cancer and were not detected in type II cancers using this panel of loci. These data tend to support the hypothesis that type I and type II endometrial cancers will exhibit distinct patterns of gene silencing based on promoter hypermethylation events.

Up-regulation and nuclear localization of beta-catenin in endometrial carcinoma in response to progesterone therapy

Ovarian hormones are considered to be capable of regulating expression of beta-catenins. A possible role of beta-catenin in alteration of cell morphology has been proposed, but little is known about beta-catenin expression during changes in the tumor morphology of endometrial carcinomas induced by progesterone therapy. To clarify changes in expression of beta-catenin and their relation to morphological alteration, expression of hormone receptors and several cell kinetic markers, sequential biopsy and hysterectomy specimens of 23 endometrial carcinoma and 6 complex hyperplasia with atypia (atypical hyperplasia) cases receiving progesterone therapy were investigated. In vitro assay was also conducted using two endometrial carcinoma cell lines (HEC265 and Ishikawa) expressing progesterone receptors (PRs). An increase of nuclear beta-catenin accumulation was evident during progesterone therapy in endometrial carcinomas and atypical hyperplasias. The nuclear labeling indices were significantly associated with gene mutations and alteration in morphological features in response to progesterone, independently of the status of Ki-67, p21WAF1 and p27Kip1, and hormone receptors. In HEC265 having a beta-catenin gene mutation (A32V), cytoplasmic beta-catenin levels were elevated by progesterone treatment, linked to down-regulation of PR expression, but such changes were relatively minor in Ishikawa without the gene alterations. These findings demonstrate a possible role of progesterone in regulation of beta-catenin expression in endometrial tumors. Moreover, nuclear beta-catenin accumulation, like gene abnormalities, is associated with the alteration of tumor morphology due to progesterone, indicating that beta-catenin may be a clinically useful marker of hormone therapeutic effects.

Expression of cadherins and CD44 isoforms in human endometrium and peritoneal endometriosis

BACKGROUND

To evaluate (a) cadherins and CD44 expression in normal endometrium and in peritoneal endometriosis, and (b) to correlate, their expressions with clinicopathological parameters.

METHODS

E- and N-cadherin, CD44 isoforms, CD44v3 and CD44v6 expressions were evaluated: (a) by immunoblotting in endometrium (n = 6) and in peritoneal endometriotic samples (n = 7) and, (b) by immunohistochemistry in endometrium (n = 15) and in peritoneal endometriotic samples (n = 23).

RESULTS

By immunoblotting, endometrium expressed E- and N-cadherin, CD44 isoforms, CD44v3 and CD44v6. Similar results were observed in peritoneal endometriosis. By immunohistochemistry, in endometrium, E-cadherin was restricted to epithelial cells. Its expression remained constant throughout the menstrual cycle. N-cadherin was detected in both epithelial and stromal cells in the proliferative phase but was restricted to epithelial cells in the secretory phase. CD44 immunostaining was detected in the secretory but not in the proliferative phase. Decreased expression of E-cadherin (p < 0.01) and CD44 (p < 0.01) in epithelial cells was found in peritoneal endometriosis as compared with normal endometrium. In endometriotic stromal cells, decreased CD44 expression was found. In peritoneal endometriosis, we observed a decreased expression of E-cadherin in advanced stages of the disease (p < 0.01).

CONCLUSION

Our results suggest that E-cadherin and CD44 proteins could be involved in the development of endometriotic lesions. Investigation of the mechanisms of altered adhesion molecule expression may contribute to the understanding of the behavior of endometriotic cells.

Sex steroidal regulation of vessel permeability associated with vessel endothelial cadherin (V-cadherin)

In an attempt to understand the roles of cadherins in the placenta, mRNA expression and biological function of cadherins in 3A(tPA-30-1) cells (derived from human term placenta and transformed by SV40), and in HUV-EC-C cells (derived from the endothelial cells in human umbilical cord) were studied under the influence of sex steroids. Estradiol transiently decreased the endothelial cell barrier properties (ECBP) of HUV-EC-C cells, and progesterone reversed the changes induced by estradiol. However, neither estradiol nor progesterone demonstrated any effect on cell aggregation of either 3A(tPA-30-1) or HUV-EC-C cells. Estradiol transiently decreased the level of V-cadherin and its mRNA in HUV-EC-C cells, and progesterone reversed the level decreased by estradiol. However, neither estradiol nor progesterone demonstrated any effect on the level of E-cadherin mRNA in 3A(tPA-30-1) cells. Therefore, a sex steroidal role for placental development and function related to cadherins seems to focus on the endothelial cells, plausibly via vessel permeability for the utilization of placental products.

E-cadherin and its messenger ribonucleic acid in periimplantation phase human endometrium in normal and clomiphene-treated cycles

OBJECTIVE

The purpose of this investigation was to determine whether treatment with clomiphene citrate, which is estrogenic and antiestrogenic, affects the expression of the cell adhesion molecule E-cadherin in human periimplantation phase endometrium.

STUDY DESIGN

Five healthy women were studied for two cycles each, a control and a treated (clomiphene 50 mg daily, days 5 through 9) cycle. A biopsy specimen of endometrial tissue was studied (8 to 10 days post luteinizing hormone surge) for immunohistochemical localization, Western analysis of E-cadherin with use of a highly specific monoclonal antibody to human E-cadherin, and determination of messenger ribonucleic acid for E-cadherin by reverse transcription-polymerase chain reaction by use of oligonucleotide primers specific to E-cadherin and amplifying a 432 bp fragment.

RESULTS

Luteal phase plasma progesterone levels were significantly higher in clomiphene cycles. E-cadherin was immunocytochemically present in endometrium of control and treated cycles with no apparent difference in staining intensity. Western blots revealed the presence of E-cadherin. It was relatively more abundant in clomiphene-treated than control cycles but not significantly different. The message for E-cadherin gene is expressed in endometrium of control (n = 5) and clomiphene cycles (n = 4).

CONCLUSIONS

E-cadherin and its gene transcripts are expressed in periimplantation phase endometrium and are not significantly affected by clomiphene treatment.