Regulated expression of cadherin-11 in human epithelial cells: a role for cadherin-11 in trophoblast-endometrium interactions?

Trophoblast Differentiation Affects Crucial Nutritive Functions of Placental Membrane Transporters

Cytotrophoblasts are progenitor cells that proliferate and fuse to form the multinucleated syncytiotrophoblast layer, implicated in placental endocrine and transport functions. While membrane transporters play a critical role in the distribution of nutrients, hormones, and xenobiotics at the maternal-fetal interface, their selectivity to the syncytiotrophoblast layer is poorly characterized. We aimed to evaluate the regulation of placental transporters in response to trophoblast differentiation in vitro. Experiments were carried out in isolated primary human trophoblast cells before and after syncytialization. Gene expression of six molecular markers and thirty membrane transporters was investigated by qPCR analysis. Subsequently, functional expression was evaluated for proteins involved in the transplacental transfer of essential nutrients i.e., cholesterol (ABCA1, ABCG1), glucose (SLC2A1), leucine (SLC3A2, SLC7A5), and iron (transferrin receptor, TfR1). We identified that human chorionic gonadotropin, placental lactogen, endoglin, and cadherin-11 serve as optimal gene markers for the syncytialization process. We showed that trophoblast differentiation was associated with differential gene expression (mostly up-regulation) of several nutrient and drug transporters. Further, we revealed enhanced protein expression and activity of ABCG1, SLC3A2, SLC7A5, and TfR1 in syncytialized cells, with ABCA1 and GLUT1 displaying no change. Taken together, these results indicate that the syncytiotrophoblast has a dominant role in transporting essential nutrients cholesterol, leucine, and iron. Nonetheless, we present evidence that the cytotrophoblast cells may also be linked to transport functions that could be critical for the cell fusion processes. Our findings collectively yield new insights into the cellular functions associated with or altered by the trophoblast fusion. Importantly, defective syncytialization could lead to nutrient transfer imbalance, ultimately compromising fetal development and programming.

Molecular characteristics of established trophoblast-derived cell lines

INTRODUCTION

Research on human placental development and function lacks a conclusive in vivo model. To investigate the intracellular molecular mechanisms in trophoblast cells, different cell lines have been established during the last decades. So far, none of these accomplishes all features of primary trophoblast, thus their suitability as well as the transferability of the results has been discussed. The aim of this study is to assess molecular markers and features matching different trophoblast subpopulations in trophoblastic cell lines to provide orientation on their suitability and relevance for distinct research questions.

METHODS

The commonly used trophoblastic cell lines, BeWo, JEG-3, HTR-8/SVneo, AC1-M59, AC1-M32, ACH-3P and Swan71 were selected. qPCR and immunoblotting were used to determine expression of characteristic molecular markers. C14MC, C19MC and miR-371-3 miRNA expression were investigated by real time PCR. Proliferation, migration and network stabilization assays were performed. Hormone secretion was determined by chemiluminescent-immunoassays. DNA profiles were obtained by Short Tandem Repeat (STR)-genotyping.

RESULTS

Immortalized cell lines differ from choriocarcinoma-derived ones in the expression of HLA-G, E-cadherin, N-cadherin, VE-cadherin, cadherin-11, cytokeratin 7, vimentin, ADAM12 and PRG2. Compared to choriocarcinoma-derived cell lines, expression of C19MC and hormone secretion were almost absent in immortalized cell lines. Conversely, they express C14MC and exhibit higher migration and network stabilization.

DISCUSSION

The data presented will help justify the use of a cell line to evaluate distinct features of trophoblast biology and pathology. In general, characteristics and markers of choriocarcinoma derived cell lines seem to be more similar to in vivo trophoblast than immortalized cell lines and thus might be regarded as more suitable models.

Differential DNA Methylation in Placenta Associated With Maternal Blood Pressure During Pregnancy

Abnormal blood pressure during pregnancy is associated with impaired fetal growth, predisposing the offspring to cardiometabolic abnormalities over the life-course. Placental DNA methylation may be the regulatory pathway through which maternal blood pressure influences fetal and adult health outcomes. Epigenome-wide association study of 301 participants with placenta sample examined associations between DNA methylation and millimetre of mercury increases in systolic and diastolic blood pressure in each trimester. Findings were further examined using gene expression, gene pathway, and functional annotation analyses. Cytosine-(phosphate)-guanine (CpGs) known to be associated with cardiometabolic traits were evaluated. Increased maternal systolic and diastolic blood pressure were associated with methylation of 3 CpGs in the first, 6 CpGs in the second, and 15 CpGs in the third trimester at 5% false discovery rate (P values ranging from 6.6×10-15 to 2.3×10-7). Several CpGs were enriched in pathways including cardiovascular-metabolic development (P=1.0×10-45). Increased systolic and diastolic blood pressure were associated with increased CpG methylation and gene expression at COL12A1, a collagen family gene known for regulatory functions in the heart. Out of 304 previously reported CpGs known to be associated with cardiometabolic traits, 36 placental CpGs were associated with systolic and diastolic blood pressure in our data. The present study provides the first evidence for associations between placental DNA methylation and increased maternal blood pressure during pregnancy at genes implicated in cardiometabolic diseases. Identification of blood pressure-associated methylated sites in the placenta may provide clues to early origins of cardiometabolic dysfunction and inform guidelines for early prevention. Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00912132.

Molecular Signaling Regulating Endometrium-Blastocyst Crosstalk

Implantation of the embryo into the uterine endometrium is one of the most finely-regulated processes that leads to the establishment of a successful pregnancy. A plethora of factors are released in a time-specific fashion to synchronize the differentiation program of both the embryo and the endometrium. Indeed, blastocyst implantation in the uterus occurs in a limited time frame called the "window of implantation" (WOI), during which the maternal endometrium undergoes dramatic changes, collectively called "decidualization". Decidualization is guided not just by maternal factors (e.g., estrogen, progesterone, thyroid hormone), but also by molecules secreted by the embryo, such as chorionic gonadotropin (CG) and interleukin-1β (IL-1 β), just to cite few. Once reached the uterine cavity, the embryo orients correctly toward the uterine epithelium, interacts with specialized structures, called pinopodes, and begins the process of adhesion and invasion. All these events are guided by factors secreted by both the endometrium and the embryo, such as leukemia inhibitory factor (LIF), integrins and their ligands, adhesion molecules, Notch family members, and metalloproteinases and their inhibitors. The aim of this review is to give an overview of the factors and mechanisms regulating implantation, with a focus on those involved in the complex crosstalk between the blastocyst and the endometrium.

CircTRNC18 inhibits trophoblast cell migration and epithelial-mesenchymal transition by regulating miR-762/Grhl2 pathway in pre-eclampsia

Dysfunctions of epithelial-mesenchymal transition (EMT)-regulated cell migration and invasion have been involved in the pathogenesis of pre-eclampsia (PE). However, the role of circRNAs in EMT of PE has not been widely investigated. In this study, we identified that circTNRC18 was upregulated in PE placentas compared with normal pregnancy placentas. Moreover, circTNRC18 negatively regulated trophoblast cell migration and EMT. Overexpression of circTNRC18 reduced while depletion of circTNRC18 enhanced trophoblast cell migration and EMT. Mechanistically, circTNRC18 sponged miR-762 contributed to inhibit miR-762 activity and elevated EMT-related transcriptional factor Grhl2 protein level. miR-762 expression was lower in PE placentas and played a promoting role in trophoblast cell migration and EMT. In contrast, Grhl2 was highly expressed in PE placentas. Furthermore, we confirmed that upregulation of Grhl2 by circ-TNRC18-induced inhibition of miR-762 led to trophoblast cell migration and EMT. In conclusions, circTNRC18/miR-762/Grhl2 axis plays a key role in trophoblast cell migration and EMT. circTNRC18/miR-762/Grhl2 axis may be a potential therapeutic target in PE.

CD73, CD90, CD105 and Cadherin-11 RT-PCR Screening for Mesenchymal Stem Cells from Cryopreserved Human Cord Tissue

Background and Objectives

Mesenchymal stem cells (MSCs) are self-renewing, non-specialized cells used clinically in tissue regeneration and sourced from bone marrow, peripheral blood, umbilical cord blood and umbilical cord tissue (UCT). To demonstrate an alternative method for MSC detection, cryopreserved UCT and expanded MSC were screened for MSC markers CD73, CD90, CD105 and CDH-11 by RT-PCR.

Methods and Results

Human UCT were washed, sectioned, cryopreserved with 10% DMSO and stored in the vapor phase of liquid nitrogen. Fresh and frozen UCT samples were expanded for MSC. UCT and MSC were processed for RNA and screened for CD73, CD90, CD105 and CDH-11 mRNA by RT-PCR. CD73, CD90 and CD105 were detected by flow cytometry and CDH-11 was detected by Western blotting. Short and long-term frozen UCT shows a loss of mRNA expression for CD73 at 33.2±34.0%, CD90 at 6.2±8.2%, CD105 at 17.7±21.6% and CDH-11 at 30.1±26.7% but was not statistically significant to indicate the deterioration. Expanded MSCs from fresh UCT expressed 0.09±0.07-fold CD73, 0.17±0.11-fold CD90, 0.04±0.06-fold CD105 and 0.14±0.08-fold CDH-11. Expanded MSCs from frozen UCTs expressed 0.09±0.06-fold CD73, 0.13±0.06-fold CD90, 0.04±0.05-fold CD105 and 0.11±0.06-fold CDH-11 and confirmed by flow cytometry and Western blotting.

Conclusion

CD73, CD90, CD105 and CDH-11 were detected by RT-PCR in cryopreserved UCT and MSC expansion. CDH-11 appears as a useful single target MSC marker for quick screening.

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.

Local and systemic factors and implantation: what is the evidence?

Significant progress has been made in the understanding of embryonic competence and endometrial receptivity since the inception of assisted reproductive technology. The endometrium is a highly dynamic tissue that plays a crucial role in the establishment and maintenance of normal pregnancy. In response to steroid sex hormones, the endometrium undergoes marked changes during the menstrual cycle that are critical for acceptance of the nascent embryo. There is also a wide body of literature on systemic factors that impact assisted reproductive technology outcomes. Patient prognosis is impacted by an array of factors that tip the scales in her favor or against success. Recognizing the local and systemic factors will allow clinicians to better understand and optimize the maternal environment at the time of implantation. This review will address the current literature on endometrial and systemic factors related to impaired implantation and highlight recent advances in this area of reproductive medicine.

Scrutinising the regulators of syncytialization and their expression in pregnancy-related conditions

The placenta is important for the success of gestation and foetal development. In fact, this specialized pregnancy organ is essential for foetal nourishment, support, and protection. In the placenta, there are different cell populations, including four subtypes of trophoblasts. Cytotrophoblasts fuse and differentiate into the multinucleated syncytiotrophoblast (syncytialization). Syncytialization is a hallmark of placentation and is highly regulated by numerous molecules with distinct roles. Placentas from pregnancies complicated by preeclampsia, intrauterine growth restriction or trisomy 21 have been associated with a defective syncytialization and an altered expression of its modulators. This work proposes to review the molecules that promote or inhibit both fusion and biochemical differentiation of cytotrophoblasts. Moreover, it will also analyse the syncytialization modulators abnormally expressed in pathological placentas, highlighting the molecules that may contribute to the aetiology of these diseases.

AP-1 Transcription Factors c-FOS and c-JUN Mediate GnRH-Induced Cadherin-11 Expression and Trophoblast Cell Invasion

GnRH is expressed in first-trimester human placenta and increases cell invasion in extravillous cytotrophoblasts (EVTs). Invasive phenotypes have been reported to be regulated by transcription factor activator protein 1 (AP-1) and mesenchymal cadherin-11. The aim of our study was to investigate the roles of AP-1 components (c-FOS/c-JUN) and cadherin-11 in GnRH-induced cell invasion in human EVT cells. Phosphorylated c-FOS and phosphorylated c-JUN were detected in the cell column regions of human first-trimester placental villi by immunohistochemistry. GnRH treatment increased c-FOS, c-JUN, and cadherin-11 mRNA and protein levels in immortalized EVT (HTR-8/SVneo) cells. Moreover, GnRH treatment induced c-FOS and c-JUN protein phosphorylation and nuclear accumulation. Pretreatment with antide, a GnRH antagonist, attenuated GnRH-induced cadherin-11 expression. Importantly, basal and GnRH-induced cadherin-11 expression and cell invasion were reduced by small interfering RNA-mediated knockdown of c-FOS, c-JUN, and cadherin-11 in HTR-8/SVneo cells. Our results suggest that GnRH induces the expression and phosphorylation of the AP-1 transcription factors c-FOS and c-JUN in trophoblast cells, which contributes to GnRH-induced elevation of cadherin-11 expression and cell invasion.

Differential methylation of genes associated with cell adhesion in preeclamptic placentas

Preeclampsia (PE), a hypertensive disorder of pregnancy, is hypothesized to be associated with, if not mechanistically related to abnormal placental function. However, the exact mechanisms regulating the pathogenesis of PE remain unclear. While many studies have investigated changes in gene expression in the PE placenta, the role of epigenetics in PE associated placental dysfunction remains unclear. Using the genome-wide Illumina Infinium Methylation 450 BeadChip array, we analyzed gene-specific alterations in DNA methylation in placental biopsies collected from normal pregnant women delivering at term (n = 14), with term PE (≥37 weeks; n = 19) or with preterm PE (<37 weeks, n = 12). Of the 485,582 gene loci on the array, compared to controls, 229 loci were differentially methylated in PE placentas and 3411 loci were differentially methylated in preterm PE (step up p-value <0.05 and >5% methylation difference). Functional annotation of the differentially methylated genes in preterm PE placentas revealed a 32 gene cluster in the cadherin and cell adhesion functional groups (Benjamini p<0.00001). Hypermethylation of CDH11 (p = 0.0143), COL5A1 (p = 0.0127) and TNF (p = 0.0098) and hypomethylation of NCAM1 (p = 0.0158) was associated with altered mRNA expression in preterm PE placentas. Demethylation of first trimester extravillous trophoblast cells resulted in altered CDH11 (p = 0.0087), COL5A1 (p = 0.0043), NCAM1 (p = 0.0260) and TNF (p = 0.0022) mRNA expression. These studies demonstrate aberrant methylation, correlating with disease severity, in PE placentas. Furthermore, we provide evidence that disruption of gene-specific methylation in preterm PE placentas and first trimester trophoblasts is significantly associated with altered gene expression demonstrating that epigenetic modifications early in pregnancy can have effects on trophoblast function contributing to PE.

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.

Submucous fibroids and infertility: Effect of hysteroscopic myomectomy and factors influencing outcome

BACKGROUND

Submucosal myomas are associated with infertility and may be treated by hysteroscopic resection.

OBJECTIVE

The aim of this retrospective study was to analyze 37 subfertile patients who unnderwent hysteroscopic myomectomy in a tertiary care center with particular regard to their postprocedure reproductive outcome.

MATERIALS AND METHODS

The entire patient group (n = 37) underwent the procedure between March 2004 and March 2010. The submucosal myomas were type 0 (n = 27), type 1 (n = 8), and type 2 (n = 2). The mean myoma size was 2.1 cm; mean duration of the procedure was 54 mins and mean follow-up was 26 ± 10 months. 22 patients had one or more associated infertility factors.

RESULTS

The complication rate was 5.4%. 11 patients (29.7%) conceived after the procedure. The pregnancy rate was better when myoma was the exclusive etiology of infertility (40%), when the myoma was completely intracavitary (33.3%), when the lesion was ≥ 30 mm in size (50%), and there were no associated intramural fibroids.

CONCLUSION

Hysteroscopic myomectomy is a safe procedure to enhance fertility especially in cases with unexplained infertility.

Twist modulates human trophoblastic cell invasion via regulation of N-cadherin

The invasion of extravillous cytotrophoblasts (EVT) into the underlying maternal tissues and vasculature is a key step in human placentation. The molecular mechanisms involved in the development of the invasive phenotype of EVT include many that were first discovered for their role in cancer cell metastasis. Previous studies have demonstrated that N-cadherin and its regulatory transcription factor Twist play important roles in the onset and progression of cancers, but their roles in human trophoblastic cell invasion is not clear. The goal of the study was to examine the role of Twist and N-cadherin in human trophoblastic cell invasion. Twist and N-cadherin mRNA and protein levels were determined by RT-PCR and Western blotting in human placental tissues, highly invasive EVT, and poorly invasive JEG-3 and BeWo cells. Whether IL-1β and TGF-β1 regulate Twist mRNA and protein levels in the EVT was also examined. A small interfering RNA strategy was employed to determine the role of Twist and N-cadherin in HTR-8/SVneo cell invasion. Matrigel assays were used to assess cell invasion. Twist and N-cadherin were highly expressed in EVT but were poorly expressed in JEG-3 and BeWo cells. IL-1β and TGF-β1 differentially regulated Twist expression in EVT in a time- and concentration-dependent manner. Small interfering RNA specific for Twist decreased N-cadherin and reduced invasion of HTR-8/SVneo cells. Similarly, a reduction in N-cadherin decreased the invasive capacity of HTR-8/SVneo cells. Twist is an upstream regulator of N-cadherin-mediated invasion of human trophoblastic cells.

Molecular and cellular mechanisms of mammalian cell fusion

The fusion of one cell with another occurs in development, injury and disease. Despite the diversity of fusion events, five steps in sequence appear common. These steps include programming fusion-competent status, chemotaxis, membrane adhesion, membrane fusion, and post-fusion resetting. Recent advances in the field start to reveal the molecules involved in each step. This review focuses on some key molecules and cellular events of cell fusion in mammals. Increasing evidence demonstrates that membrane lipid rafts, adhesion proteins and actin rearrangement are critical in the final step of membrane fusion. Here we propose a new model for the formation and expansion of membrane fusion pores based on recent observations on myotube formation. In this model, membrane lipid rafts first recruit adhesion molecules and align with opposing membranes, with the help of a cortical actin "wall" as a rigid supportive platform. Second, the membrane adhesion proteins interact with each other and trigger actin rearrangement, which leads to rapid dispersion of lipid rafts and flow of a highly fluidic phospholipid bilayer into the site. Finally, the opposing phospholipid bilayers are then pushed into direct contact leading to the formation of fusion pores by the force generated through actin polymerization. The actin polymerization generated force also drives the expansion of the fusion pores. However, several key questions about the process of cell fusion still remain to be explored. The understanding of the mechanisms of cell fusion may provide new opportunities in correcting development disorders or regenerating damaged tissues by inhibiting or promoting molecular events associated with fusion.

Regulated expression of ADAMTS-12 in human trophoblastic cells: a role for ADAMTS-12 in epithelial cell invasion?

Metastatic carcinoma cells exploit the same molecular machinery that allows human placental cytotrophoblasts to develop an invasive phenotype. As altered expression levels of ADAMTS (ADisintegrin And Metalloproteinase with ThromboSpondin repeats) subtypes have been associated with cancer progression, we have examined the function and regulation of members of this gene family in epithelial cell invasion using cultures of highly invasive extravillous cytotrophoblasts and the poorly invasive JEG-3 cytotrophoblast cell line as model systems. Of the multiple ADAMTS subtypes identified in first trimester human placenta and these two trophoblastic cell types, only ADAMTS-12 was preferentially expressed by extravillous cytotrophoblasts. Transforming growth factor-β1 and interleukin-1β, two cytokines that promote and restrain cytotrophoblast invasion in vitro, were also found to differentially regulate trophoblastic ADAMTS-12 mRNA levels. Loss- or gain-of-function studies confirmed that ADAMTS-12, independent of its proteolytic activity, plays a specific, non-redundant role in trophoblast invasion. Furthermore, we demonstrated that ADAMTS-12 regulated cell-extracellular matrix adhesion and invasion through a mechanism involving the αvβ3 integrin heterodimer. This study identifies a novel biological role for ADAMTS-12, and highlights the importance and complexity of its non-proteolytic domain(s) pertaining to its function.

Endocrinology and cell signaling in human villous trophoblast

In humans, the placenta that forms by an implantation process in the maternal uterus allows the development of the embryo and the fetus by exchanging ions, metabolites, and wastes and by producing specific hormones (steroids and proteins) with the levels of secretion often surpassing the levels of other endocrine organs. The process of placental development involves two pathways of differentiation that lead to the formation of two distinct phenotypes: villous trophoblast (fusion phenotype) and extravillous trophoblast (proliferative/invasive phenotype). In this chapter we describe the current methods to study villous trophoblast differentiation and the cell-cell fusion of the cytotrophoblast cells.

Promotion of human trophoblasts invasion by gonadotropin-releasing hormone (GnRH) I and GnRH II via distinct signaling pathways

The potential roles of GnRH I and GnRH II have been assigned in promoting the invasive capacity of human trophoblasts by regulating matrix metalloproteinases-2 and -9, type I tissue inhibitor of matrix metalloproteinase, and urokinase plasminogen activator/plasminogen activator inhibitor protease systems during human placentation, and GnRH II has been shown to be more potent than GnRH I. However, the mechanisms for the differential effects of these two hormones remain unclear. In this study, we examined the invasion-promoting effects and the signaling pathways of GnRH I and GnRH II in human trophoblasts. The data revealed that both GnRH I and GnRH II were key autocrine and/or paracrine regulators in facilitating trophoblast invasion. The GnRH receptor antagonist (Antide) and specific small interfering RNA for GnRH receptor inhibited the regulatory effects of GnRH I, but not GnRH II, on trophoblast invasion. Both GnRH I and II activated protein kinase C, ERK1/2, and c-Jun N-terminal kinase to mediate their effects on trophoblast invasion, whereas only GnRH II elicited invasion-promoting action through transactivating the tyrosine kinase activity of epidermal growth factor receptor in trophoblasts. Our observations elucidate a ligand-dependent selective cross-communication between GnRH receptor and epidermal growth factor receptor signaling systems in human trophoblastic cell, and this would further our understanding on the differentially biological significance of these two forms of GnRH in extrapituitary tissues.

Endothelial and virgultar cell formations in the mammalian lymph node sinus: endothelial differentiation morphotypes characterized by a special kind of junction (complexus adhaerens)

The lymph node sinus are channel structures of unquestionable importance in immunology and pathology, specifically in the filtering of the lymph, the transport and processing of antigens, the adhesion and migration of immune cells, and the spread of metastatic cancer cells. Our knowledge of the cell and molecular biology of the sinus-forming cells is still limited, and the origin and biological nature of these cells have long been a matter of debate. Here, we review the relevant literature and present our own experimental results, in particular concerning molecular markers of intercellular junctions and cell differentiation. We show that both the monolayer cells lining the sinus walls and the intraluminal virgultar cell meshwork are indeed different morphotypes of the same basic endothelial cell character, as demonstrated by the presence of a distinct spectrum of general and lymphatic endothelial markers, and we therefore refer to these cells as sinus endothelial/virgultar cells (SEVCs). These cells are connected by unique adhering junctions, termed complexus adhaerentes, characterized by the transmembrane glycoprotein VE-cadherin, combined with the desmosomal plaque protein desmoplakin, several adherens junction plaque proteins including alpha- and beta-catenin and p120 catenin, and components of the tight junction ensemble, specifically claudin-5 and JAM-A, and the plaque protein ZO-1. We show that complexus adhaerentes are involved in the tight three-dimensional integration of the virgultar network of SEVC processes along extracellular guidance structures composed of paracrystalline collagen bundle "stays". Overall, the SEVC system might be considered as a local and specific modification of the general lymphatic vasculature system. Finally, physiological and pathological alterations of the SEVC system will be presented, and the possible value of the molecular markers described in histological diagnoses of autochthonous lymph node tumors will be discussed.

Chapter 12. Placental remodeling of the uterine vasculature

In eutherian mammals, the first functional organ is the placenta, a transient structure that is rapidly assembled in the extraembryonic compartment. By necessity the placenta develops in advance of the embryo, which it supports in utero by performing many of the same functions that the lungs, gastrointestinal tract, and urinary system carry out after birth. Specialized epithelial cells that arise from the placenta, termed cytotrophoblasts (CTBs), are responsible for redirecting maternal blood to the developing conceptus, which occurs as a result of the cells' aggressive invasion through the maternal endometrial stroma (interstitial invasion) and resident blood vessels (endovascular invasion). The latter process involves displacement of maternal endothelium and induction of apoptosis in the surrounding smooth muscle. Together, these events result in a reduction of blood vessel elasticity and increased blood flow. In the past, investigations of human CTB endovascular invasion have been limited to immunohistochemical examination of tissue sections. In this chapter, we will discuss the use of in vitro and in vivo techniques that have been recently adapted for the study of the complex events that occur during CTB endovascular invasion. As an introduction, we provide background on placental anatomy and the molecular basis of CTB behaviors. To follow, we present techniques used in the isolation and culture of primary CTBs and chorionic villous explants. Approaches for identifying trophoblast-modified blood vessels in placental tissue sections are also described. Next, we review methods used by other groups to study CTB/endothelial interactions in culture focusing on techniques that employ isolated cells and chorionic explants. Finally, we conclude with methods devised by our group and others to explore the complex heterotypic cell-cell interactions that occur as CTBs invade blood vessels in vivo in the nude mouse.

Expression of adhesion molecules during normal pregnancy

We review the available information regarding the role of adhesive molecules as potential participants in the complex events of fertilization, embryogenesis, implantation and placentation. Studies that specifically relate to the expression and modulation of adhesive molecules in fertilization, embryogenesis, and implantation have been identified in the literature and by Medline searches. Cell-cell and cell-extracellular matrix interactions play a critical role in various developmental processes and in the cascade of events that lead to implantation and to the normal development of the fetus during pregnancy. Adhesion molecules influence, directly or indirectly, numerous aspects of cell behaviour, cell migration, cell growth, cell survival, cell proliferation, angiogenesis, invasion and metastasis.

Expression of ADAMTS-5/implantin in human decidual stromal cells: regulatory effects of cytokines

BACKGROUND

The restricted expression of ADAMTS-5 (A Disintegrin And Metalloproteinase with ThromboSpondin repeats-5) to the maternal-fetal interface in mice has led to this novel metalloproteinase being assigned the trivial name 'implantin'.

METHODS

As a first step in determining whether ADAMTS-5 also contributes to the implantation process in humans, we have examined the spatiotemporal expression of this ADAMTS subtype in the endometrium during the menstrual cycle and pregnancy by immunohistochemical analysis. A quantitative competitive PCR (QC-PCR) strategy and western blotting were subsequently used to determine whether interleukin (IL)-1beta and transforming growth factor (TGF)-beta1, two cytokines involved in the formation of the maternal-fetal interface, were capable of regulating ADAMTS-5 messenger RNA (mRNA) and protein levels in primary cultures of stromal cells isolated from first trimester decidual tissues.

RESULTS

ADAMTS-5 expression in the stroma of the human endometrium correlates with decidualization of this cellular compartment in vivo. IL-1beta was found to increase (P < 0.05) whereas TGF-beta1 decreased (P < 0.05) ADAMTS-5 mRNA and protein levels in decidual stromal cell cultures in a concentration- and time-dependent manner. These regulatory effects were attenuated by function-perturbing antibodies directed against either cytokine.

CONCLUSIONS

ADAMTS-5 expression is restricted to decidualized stromal cells of the human endometrium in vivo and is subject to regulation by cytokines in vitro.

Concerted upregulation of CLP36 and smooth muscle actin protein expression in human endometrium during decidualization

The human endometrium prepares for implantation of the blastocyst by reorganization of its whole cellular network. Endometrial stroma cells change their phenotype starting around the 23rd day of the menstrual cycle. These predecidual stroma cells first appear next to spiral arteries, and after implantation these cells further differentiate into decidual stroma cells. The phenotypical changes in these cells during decidualization are characterized by distinct changes in the actin filaments and filament-related proteins such as alpha-actinin. The carboxy-terminal LIM domain protein with a molecular weight of 36 kDa (CLP36) is a cytoskeletal component that has been shown to associate with contractile actin filaments and to bind to alpha-actinin supporting a role for CLP36 in cytoskeletal reorganization and signal transduction by binding to signaling proteins. The expression patterns of CLP36, alpha-actinin and actin were studied in endometrial stroma cells from different stages of the menstrual cycle and in decidual stroma cells from the 6th week of gestation until the end of pregnancy. During the menstrual cycle, CLP36 is only expressed in the luminal and glandular epithelium but not in endometrial stroma cells. During decidualization and throughout pregnancy, a parallel upregulation of CLP36 and smooth muscle actin, an early marker of decidualization in the baboon, was observed in endometrial decidual cells. Since both proteins maintain a high expression level throughout pregnancy, a role of both proteins is suggested in the stabilization of the cytoskeleton of these cells that come into close contact with invading trophoblast cells.

Differential effects of interleukin-1beta and transforming growth factor-beta1 on the expression of the inflammation-associated protein, ADAMTS-1, in human decidual stromal cells in vitro

BACKGROUND

The pro-inflammatory cytokine, interleukin-1 beta (IL-1beta) promotes the proteolytic degradation of the extracellular matrix (ECM) of maternal decidua, a critical step in pregnancy that is counterbalanced by the expression of the anti-inflammatory cytokine, transforming growth factor-beta 1 (TGF-beta1). Recently, the inflammation-associated protein, ADAMTS-1, a member of the ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin repeats) gene family of metalloproteinases has been assigned a central role in the formation and organization of tissues. In view of these observations, we have hypothesized that ADAMTS-1 contributes to the cytokine-mediated remodelling of decidual ECM.

METHODS

The spatiotemporal expression of ADAMTS-1 in human endometrium was examined by immunohistochemistry. A quantitative-competitive (QC)-PCR strategy and western blot analysis was then employed to determine whether IL-1beta and TGF-beta1 regulate ADAMTS-1 mRNA and protein expression levels in primary cultures of stromal cells isolated from first trimester decidua.

RESULTS

ADAMTS-1 expression is associated with decidualization of the endometrial stroma in vivo. IL-1beta increased whereas TGF-beta1 decreased ADAMTS-1 mRNA and protein levels in decidual stromal cell cultures in a concentration- and time-dependent manner. These regulatory effects were attenuated by function-perturbing antibodies specific for either cytokine.

CONCLUSION

IL-1beta and TGF-beta1 differentially regulate ADAMTS-1 expression in human decidual stromal cells.

PTHrP induces changes in cell cytoskeleton and E-cadherin and regulates Eph/Ephrin kinases and RhoGTPases in murine secondary trophoblast cells

The differentiation of murine trophoblast giant cells (TGCs) is well characterised at the molecular level and, to some extent, the cellular level. Currently, there is a rudimentary understanding about factors regulating the cellular differentiation of secondary TGCs. Using day 8.5 p.c.-ectoplacental cone (EPC) explant in serum-free culture, we have found parathyroid hormone-related protein (PTHrP) to regulate cellular changes during TGC differentiation. PTHrP greatly stimulated the formation and organisation of actin stress fibres and actin expression in trophoblast outgrowth. This coincided with changing cell shape into a flattened/fibroblastic morphology, suppression of E-cadherin expression, and increased cell spreading in culture. PTHrP also increased the nuclear staining of beta-catenin and, similar to activator protein-2gamma (AP-2gamma), showed microtubule-dependent nuclear localisation in vitro. These cellular and behavioural changes correlated with changes in the expression of RhoGTPases and in both expression and phosphorylation of Eph/Ephrin kinases. The effects of PTHrP on trophoblast cellular differentiation were abolished after blocking its action. In conclusion, PTHrP provides an excellent example of the extrinsic factors that, through their network of activities, plays an important role in cellular differentiation of secondary TGCs.

E-cadherin in the assessment of aberrant placental cytotrophoblast turnover in pregnancies complicated by pre-eclampsia

E-cadherin is a cell-cell adhesion protein expressed in cytotrophoblasts, which is lost as they differentiate and syncytialise. We have exploited E-cadherin as a marker of cytotrophoblasts to investigate villous tissue composition in first and third trimester placentae, both in normal pregnancy and pregnancies complicated by pre-eclampsia. We have achieved this by measuring expression levels of E-cadherin at the mRNA level, using Q-PCR, and at the protein level using semi-quantitative Western blotting. We have also combined E-cadherin immunohistochemistry with morphometric analysis of area measurements to define cytotrophoblast and syncytiotrophoblast compartments. This novel use of E-cadherin has revealed a decrease in the proportion of cytotrophoblasts in villous tissue as pregnancy progresses, in the absence of changes in syncytiotrophoblast cover. Moreover, in pre-eclampsia, placental E-cadherin was raised compared to syncytiotrophoblast, suggesting either exaggerated cytotrophoblast proliferation or impaired cytotrophoblast differentiation, both alterations of potential pathogenic importance.

Cadherins in maternal-foetal interactions: red queen with a green beard?

Cadherins are homophilic cell surface adhesion proteins, some of which mediate interactions between maternal and foetal tissues during mammalian pregnancy. David Haig suggested that these proteins may exhibit 'green-beard gene' effects, whereby the nature of binding between identical alleles in mother and foetus leads to differential levels of resource transfer. The selfish effects of such self-recognizing alleles should, however, be suppressed over evolutionary time by unlinked genes, which is expected to lead to antagonistic coevolution between placentally expressed cadherins and unlinked modifiers. Such molecular coevolution should leave a signature of positive selection, with high ratios of non-synonymous to synonymous amino acid substitution. We present evidence that three placentally expressed cadherin genes, E-cadherin, P-cadherin and VE-cadherin, have been subject to positive selection. By contrast, a 'control' cadherin that is not expressed in the placenta, H-cadherin, showed no evidence of selection. These results provide support for the hypothesis that the cadherin genes involved in maternal-foetal interactions have been subject to green-beard-effect mutations over the course of evolutionary history, leading to antagonistic coevolution with suppressing elements from the parliament of genes.

Efficacy of a Recombinant Chimeric Anti-hCG Antibody to Prevent Human Cytotrophoblasts Fusion and Block Progesterone Synthesis

PROBLEM

A recombinant chimeric antibody against hCG (cPIPP) has been engineered and expressed at high yield in plants. The purpose of this work was to enquire whether this antibody is competent to neutralize the bioactivity of hCG on human trophoblasts.

METHODS

Cytotrophoblast cells, isolated from term placentae were maintained in culture for 3 days in presence or absence of humanized chimeric anti-hCG antibodies. Progesterone secreted was quantitated by ELISA. Fusion and cyto-architecture of the cells was studied by light and electron microscopy. Modulation of E-cadherin was investigated using RT-PCR and immunocytochemistry.

RESULTS

Recombinant chimeric anti-hCG antibody blocked the synthesis of progesterone by trophoblasts. No fusion of cytotrophoblasts to form syncytium took place. E-cadherin, a vital cell adhesion molecule involved in cell-to-cell interaction did not show differentiation related decline in its expression in presence of the antibody.

CONCLUSION

Recombinant chimeric anti-hCG antibody (cPIPP) was effective to neutralize hCG induced bioactivities in the human derived trophoblast cells.

Two pathways of progesterone action in the human endometrium: implications for implantation and contraception

The endometrium is the site of implantation and pregnancy. Preparation for this important biological event relies primarily on progesterone, which takes the estrogen-primed endometrium toward a state of receptivity. As a steroid target tissue, the endometrium is also prone to abnormal growth sometimes leading to the development of hyperplasia or cancer. It is the balance between estrogen and progesterone that maintains the endometrium in a state of health and provides the synchronous timing necessary for a successful implantation to occur. In our efforts to understand the role of progesterone in the endometrium we have focused on the use of specific protein biomarkers. Based on examination of a cell adhesion molecule, the alphavbeta3 integrin, and its ligand, osteopontin, we have come to conclude that progesterone action can be direct or indirect. Progesterone acting on the stromal compartment provides paracrine mediators that influence epithelial gene expression. Conversely, acting directly, progesterone may primarily stimulate gene expression of the endometrial epithelium. The complexity of the system is extended since progesterone itself works through two different receptor isoforms. Regulated differential expression of PR-A versus PR-B also appears to fine tune the effect of progesterone on specific genes. Progesterone may also inhibit specific genes that undergo cyclic variation during the menstrual cycle. Together, using in vitro models we have shown that progesterone dynamically regulates gene expression in the endometrium and that imbalances between estrogen and progesterone may have far reaching consequences on normal cycle fecundity and on the balance between health and disease in this hormone-target tissue.

Methylation status and expression of E-cadherin and cadherin-11 in gestational trophoblastic diseases

The clinical significance of cadherins in gestational trophoblastic diseases (GTD) is not fully understood. In this study, the expression of E-cadherin and cadherin-11 in 12 normal placentas, 32 cases of hydatidiform mole (HM) including 15 complete HMs and 17 partial HMs, and five choriocarcinomas was investigated by immunohistochemistry and correlated with follow-up of HMs. Cases with available frozen blocks were further analyzed by western blot and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). Methylation of E-cadherin was investigated by methylation-specific PCR in six normal first trimester placentas, 19 HMs and their associated deciduas. E-cadherin expression was localized to cytotrophoblast and intermediate trophoblast whereas cadherin-11 was expressed in syncytiotrophoblast, intermediate trophoblast, and decidua. Immunoreactivity of E-cadherin was reduced in choriocarcinoma and complete HM when compared with that in normal first trimester placenta (P < 0.01, P = 0.04). Hypermethylation of E-cadherin was demonstrated in three complete HMs with the lowest level of E-cadherin. Compared with normal first trimester placenta, immunoreactivity of cadherin-11 was higher in complete HM (P = 0.02), but lower in choriocarcinoma (P = 0.02). Such differential expression was confirmed by western blot and semiquantitative RT-PCR. No obvious association was observed between the development of persistent trophoblastic disease with the expression of E-cadherin and cadherin-11.

Temporal regulation of gene expression during the expected window of receptivity in the rhesus monkey endometrium

Progesterone has been shown to regulate a number of genes and gene networks in the primate endometrium. This action of progesterone is essential to provide an appropriate milieu for embryo-endometrial communication that can lead to implantation and the successful initiation of pregnancy. A temporal regulation of endometrial genes is most likely required to achieve an appropriate state of receptivity in the primate endometrium. Using simulated menstrual cycles in the rhesus monkey, endometrial tissue was harvested at days that encompass the expected window of receptivity (4-10 days after the estradiol surge) and subsequently converted to cycle day-specific cDNA populations. Using differential display reverse transcriptase-polymerase chain reaction, 12 cDNA fragments were isolated and sequenced whose mRNA levels were elevated during this time frame. The temporal expression patterns of these mRNAs were confirmed by semiquantitative polymerase chain reaction. Two of these fragments exhibited high homology to previously characterized human genes: 1) secretory leukocyte protease inhibitor, also known as antileukoprotease, an endometrial neutrophil elastase inhibitor with antibacterial and anti-inflammatory properties; and 2) syncytin, also known as endogenous retrovirus W envelope protein, a highly fusogenic membrane glycoprotein that induces formation of giant syncytia and is believed to be important in decidual and placental development. The temporal regulation of these genes by progesterone supports their likely role in the orchestration of molecular and cellular events that are required to achieve a state of receptivity in the primate endometrium.

Cadherin-11 modulates the terminal differentiation and fusion of human trophoblastic cells in vitro

E-cadherin and cadherin-11 are two members of the cadherin gene family of cell adhesion molecules that are differentially expressed during the aggregation, differentiation, and fusion of trophoblasts isolated from the human term placenta. E-cadherin expression is highest in cytotrophoblasts and decreases as these mononucleate cells undergo terminal differentiation and fusion. In contrast, cadherin-11 expression increases during the formation of multinucleated syncytium in these primary cultures. To define the role(s) of cadherin-11 in this developmental process, we examined the effects of ectopic cadherin-11 expression on the differentiation and fusion of JEG-3 choriocarcinoma cells, a mononucleate trophoblastic cell line. Cadherin-11 expression, but not the ectopic expression of the related cadherin subtype, cadherin-6, resulted in the formation of multinucleated syncytium in the transfected JEG-3 cell cultures. Multinucleated syncytium formation in the JEG-3 cells transfected with cadherin-11 was associated with a reduction in E-cadherin, alpha-, beta-, gamma-catenin, and p120(ctn) expression. Cadherin-11 also reduced cell proliferation and increased the levels of the mRNA transcript encoding the beta subunit of human chorionic gonadotropin, a biochemical marker of trophoblast differentiation, in these cultures. Furthermore, primary cytotrophoblasts cultured in the presence of antisense oligonucleotides specific for cadherin-11 maintained E-cadherin expression and did not undergo terminal differentiation and fusion with time in culture. Collectively, these observations demonstrate that cadherin-11 contributes to the morphological and functional differentiation of cultured mononucleate trophoblastic cells in a highly specific manner.

Effect of matrigel on human extravillous trophoblasts differentiation: modulation of protease pattern gene expression

The human placenta is characterized by extensive trophoblast invasion of the uterus. Indeed, extravillous cytotrophoblast cells invade the decidua and the upper third of uterine spiral arteries in the myometrium. This invasion is reflected in situ by the expression of specific markers. In order to study this invasion process, we have established an in vitro culture model of human extravillous trophoblast isolated from first trimester chorionic villi. The aim of this study was to investigate the effect of a composite matrix, the Matrigel required for the culture of this homogenous population of extravillous trophoblasts (EVCT), on their in vitro differentiation. The effect of Matrigel was studied on different markers characterized by immunocytochemistry and by real-time polymerase chain reaction assay of transcripts. In addition, the expression of 12 different matrix metalloproteases and their inhibitors were investigated. We show that human extravillous cytotrophoblasts acquire an invasive phenotype on Matrigel associated with a specific pattern of protease gene expression. This in vitro model will be of interest to study the cellular mechanisms involved in abnormal trophoblast invasion observed in poor placentation and preeclampsia.

Antiphospholid antibodies regulate the expression of trophoblast cell adhesion molecules

OBJECTIVE

To examine the effect of antiphospholipid antibodies on trophoblast expression of adhesion molecules.

DESIGN

Primary cytotrophoblast cell cultures.

SETTING

Department of Obstetrics and Gynecology, Catholic University, Rome, Italy.

PATIENT(S)

Five normal pregnant women underwent uncomplicated vaginal delivery at 36 weeks of gestation.

INTERVENTION(S)

IgG antibodies were isolated from a patient with antiphospholipid syndrome and from a normal control subject, using protein-G Sepharose columns. Cytotrophoblast cells were dispersed in bicarbonate buffer containing trypsin and DNAse I.

MAIN OUTCOME MEASURE(S)

We investigated the effects of antiphospholipid antibodies on trophoblast adhesion molecules (alpha1 and alpha5 integrins, E and VE cadherins), both at the protein and mRNA levels.

RESULT(S)

The alpha1 and alpha5 integrins were present in trophoblast cells from 24 hours of culture. Treatment with IgG that were obtained from the patient with antiphospholipid syndrome significantly decreased alpha1 integrin and increased alpha5 integrin at both the mRNA and protein levels. Furthermore, IgG with antiphospholipid antibodies activities induced VE-cadherin down-regulation and the E-cadherin up-regulation at protein and mRNA levels compared with control IgG or untreated cells.

CONCLUSION(S)

The results suggest that the inadequate trophoblastic invasion, induced by antiphospholipid antibodies, can be the result of abnormal trophoblast adhesion molecules expression.

Expression and localization of P-, K-, and OB-cadherin in the prepubertal rat ovary

Classical and atypical cadherins mediate calcium-dependent cell adhesion and play an important role in morphogenetic processes. We have shown, previously, N- and E-cadherin expression in the rat ovary. This expression, however, was not associated with specific follicle-restructuring events such as antrum formation and segregation of mural from cumulus granulosa cells suggesting that other cadherins may serve this function. In this study, RT-PCR and immunostaining techniques showed that three other cadherins are expressed throughout prepubertal ovarian development in the rat: one classical (P-) cadherin, and two atypical (K- and OB-) cadherins. RT-PCR analysis of isolated ovarian tissue compartments (granulosa cells and the residual ovarian tissue) agreed with the immunostaining results. Immunostaining showed P- and K-cadherin expression by granulosa, as well as thecal/interstitial cells, and also in oocytes of primordial follicles. P-cadherin expression was absent in oocytes of follicles in later stages of development compared to K-cadherin, which was found in oocytes at all stages of folliculogenesis. P-, K-, and OB-cadherin were expressed by the ovarian surface epithelial cells of neonatal animals but only P- and OB-cadherin expression were maintained in these cells in 25 day-old animals. Cellular OB-cadherin staining was absent in follicles at all stages of development and its expression was restricted to the ovarian hilar region and portions of the stroma. In summary, cadherin expression and distribution profiles changed during ovarian growth and folliculogenesis suggesting a role for cadherins in organizational and morphogenetic processes within the developing rat ovary.

Plasma membrane-associated pY397FAK is a marker of cytotrophoblast invasion in vivo and in vitro

During human pregnancy specialized placental cells of fetal origin, termed cytotrophoblasts, invade the uterus and its blood vessels. This tumor-like process anchors the conceptus to the mother and diverts the flow of uterine blood to the placenta. Previously, we showed that the expression of molecules with important functional roles, including a number of extracellular matrix integrin receptors, is precisely modulated during cytotrophoblast invasion in situ. Here we exploited this observation to study the role of the focal adhesion kinase (FAK), which transduces signals from the extracellular matrix and recruits additional signaling proteins to focal adhesions. Immunolocalization studies on tissue sections showed that FAK is expressed by cytotrophoblasts in all stages of differentiation. Because extracellular matrix-induced integrin clustering results in FAK (auto)phosphorylation on tyrosine 397 (Y397FAK), we also localized this form of the molecule. Immunolocalization experiments detected Y397FAK in a subset of cytotrophoblasts near the surface of the uterine wall. To assess the functional relevance of this observation, we used an adenovirus strategy to inhibit cytotrophoblast expression of FAK as the cells differentiated along the invasive pathway in vitro. Compared to control cells transduced with a wild-type virus, cytotrophoblasts that expressed antisense FAK exhibited a striking reduction in their ability to invade an extracellular matrix substrate. When cytotrophoblast differentiation was compromised (hypoxia in vitro, preeclampsia in vivo), Y397FAK levels associated with the plasma membrane were strikingly lower, although total FAK levels did not change. Together our results suggest that (auto)phosphorylation of Y397 on FAK is a critical component of the signaling pathway that mediates cytotrophoblast migration/invasion.

alpha-, beta-, gamma-catenin, and p120(CTN) expression during the terminal differentiation and fusion of human mononucleate cytotrophoblasts in vitro and in vivo

The cadherins play key roles in the formation and organization of the mammalian placenta by mediating cellular interactions and the terminal differentiation of trophoblastic cells. Although cadherin function is regulated by the cytoplasmic proteins, known as the catenins, the identity and expression pattern(s) of the catenins present in the trophoblastic cells of the human placenta have not been characterized. In these studies, we have determined that alpha-, beta-, gamma-catenin, and p120(ctn) expression levels are high in villous cytotrophoblasts isolated from the human term placenta but decline as these cells undergo aggregation and fusion to form syncytium with time in culture. In contrast, the expression levels of these four catenin subtypes remained constant in non-fusing JEG-3 choriocarcinoma cells at all of the time points examined in these studies. alpha-, beta-, gamma-catenin, and p120(ctn) expression was further immunolocalized to the mononucleate cells present in these two trophoblastic cell cultures. Similarly, intense immunostaining for all four catenins was detected in the mononucleate villous cytotrophoblasts of the human first trimester placenta. Collectively, these observations demonstrate that the expression levels of alpha-, beta-, gamma-catenin, and p120(ctn) are tightly regulated during the formation of multinucleated syncytium in vitro and in vivo.

Identification of cadherin-11 down-regulation as a common response of astrocytoma cells to transforming growth factor-alpha

Transforming growth factor-alpha (TGF-alpha) and its receptor are frequently co-expressed in high-grade astrocytomas, suggesting a role for TGF-alpha autocrine/paracrine loops in the malignant progression of astrocytomas. To identify genes that may be critical in mediating TGF-alpha impact on the malignant progression of astrocytomas, we have used cDNA arrays to investigate TGF-alpha effects on the gene expression profile of U-373 MG glioblastoma cells. We found that in these cells approximately 50% of the TGF-alpha regulated genes code for cell motility/invasion-related proteins. TGF-alpha action on the expression of four of these proteins, alpha-catenin, IQGAP1, RhoA, and cadherin-11, was further investigated by immunoblotting in four astrocytoma cell lines and in normal astrocytes. The results demonstrate that the effects of TGF-alpha on IQGAP1, alpha-catenin, and RhoA expression are cell-line dependent. On the other hand, under TGF-alpha treatment, cadherin-11 expression is consistently decreased in all astrocytoma cell lines tested but is increased in normal astrocytes. In addition, we found that cadherin-11 is consistently down-regulated in astrocytomas versus normal brain tissues. Altogether, these results suggest that the down-regulation of cadherin-11 is a frequent molecular event in the neoplastic transformation of astrocytes and that this down-regulation may be initiated and/or amplified by TGF-alpha autocrine/paracrine loops during tumor progression.

Endometrial receptivity and the window of implantation

Implantation is a highly co-ordinated event that involves both embryonic and endometrial participation. The endometrium expresses a sophisticated repertoire of proteins during the menstrual cycle many of which help to define a period of receptivity collectively known as the 'window of implantation'. Many of these factors, which are temporally aligned with this window, are now seen as chemical messengers that are recognized by the embryo and facilitate embryonic growth and differentiation. The use of such proteins as biomarkers has also advanced our understanding of the implantation process and may identify women with implantation failure and infertility. While the study of endometrial receptivity is still evolving, the field is growing rapidly and will probably enhance our ability to diagnose and treat couples with infertility, especially in the arena of assisted reproductive technologies (ART).

Fertility after hysteroscopic myomectomy: effect of intramural myomas associated

OBJECTIVE

The aims of this retrospective study were to evaluate the subsequent fertility and outcome of pregnancies after hysteroscopic myomectomy according to (a) the characteristics of submucous myomas and (b) the association with intramural myomas.

MATERIALS AND METHODS

From July 1994 to June 1997, 119 patients had hysteroscopic myomectomy including 31 infertile women. Among these 31 patients, the mean number of removed myomas by hysteroscopy was 1.4 (range 1-4) and the mean diameter of fibroid was 20 mm (range 10 to 50).

RESULTS

Eleven out of 31 women (35.5%) became pregnant. Thirteen pregnancies were observed including nine term deliveries, three miscarriages and one premature labor at 24 weeks of amenorrhea. A difference in delivery rate was found between patients with one submucous myoma resected and those with two or more (p=0.02). No difference in pregnancy and in delivery rates was observed according to size and location of submucous myomas. In contrast, in patients without intramural myomas, the delivery rate (p<0.03) was significantly greater and the delay of conception (p=0.05) was significantly shorter than those found in patients with intramural myomas.

CONCLUSION

Our study suggest that fertility after hysteroscopic myomectomy depend on (a) the number of submucous myomas resected and (b) the association with intramural fibroids.

N-cadherin promotes motility in human breast cancer cells regardless of their E-cadherin expression

E-cadherin is a transmembrane glycoprotein that mediates calcium-dependent, homotypic cell-cell adhesion and plays a role in maintaining the normal phenotype of epithelial cells. Decreased expression of E-cadherin has been correlated with increased invasiveness of breast cancer. In other systems, inappropriate expression of a nonepithelial cadherin, such as N-cadherin, by an epithelial cell has been shown to downregulate E-cadherin expression and to contribute to a scattered phenotype. In this study, we explored the possibility that expression of nonepithelial cadherins may be correlated with increased motility and invasion in breast cancer cells. We show that N-cadherin promotes motility and invasion; that decreased expression of E-cadherin does not necessarily correlate with motility or invasion; that N-cadherin expression correlates both with invasion and motility, and likely plays a direct role in promoting motility; that forced expression of E-cadherin in invasive, N-cadherin-positive cells does not reduce their motility or invasive capacity; that forced expression of N-cadherin in noninvasive, E-cadherin-positive cells produces an invasive cell, even though these cells continue to express high levels of E-cadherin; that N-cadherin-dependent motility may be mediated by FGF receptor signaling; and that cadherin-11 promotes epithelial cell motility in a manner similar to N-cadherin.

Anomalous cadherin expression in osteosarcoma. Possible relationships to metastasis and morphogenesis

Two isoforms of the human cadherin-11/OB-cadherin gene, the intact and the variant forms, had been isolated from an osteosarcoma cDNA library. The intact form has a typical cadherin structure, whereas the variant form, generated by alternative splicing, encodes a cytoplasmic domain that is completely different from that of the intact form and lacks a homophilic cell-cell adhesion ability. At the protein level, the secreted form generated from the intact cadherin-11 is present. We examined the expression of the intact and the variant forms of cadherin-11 in 23 primary and metastatic osteosarcomas from 22 patients by reverse transcriptase-polymerase chain reaction (RT-PCR) analyses, revealing that all 23 tumors in the patients expressed the variant form and three of them expressed it prominently. On the other hand, Western blot analyses of six tumors showed that the secreted form was strongly expressed, and furthermore, expression of N-cadherin was extremely low. Overexpression of the intact cadherin-11 cDNA in osteosarcoma cell lines demonstrated that the secreted form is derived from the intact form of cadherin-11 in osteosarcoma. Immunohistochemically, cadherin-11, N-cadherin, and beta-catenin were expressed at the cell surface of fetal osteoblasts, whereas in osteosarcoma cells, they were expressed only focally or weakly in the cytoplasm. Considering the function of cadherin in carcinomas, it is suggested that the anomalous expression of human cadherin-11 in osteosarcoma and the reduced expression of N-cadherin play a role in metastasis and the irregular morphology in the highly malignant mesenchymal tumor.

Antisteroidal compounds and steroid withdrawal down-regulate cadherin-11 mRNA and protein expression levels in human endometrial stromal cells undergoing decidualisation in vitro

The cellular mechanisms by which steroids and antisteroidal compounds modulate the function and/or integrity of the human endometrium remain poorly understood. We recently determined that the expression of the novel cadherin subtype, known as cadherin-11, is tightly regulated in endometrial stromal cells undergoing decidualisation in vivo and in vitro. To determine whether the actions of antisteroids on the endometrium are mediated, at least in part, by their ability to regulate the expression of this cell adhesion molecule, we examined the effects of the antiprogestin RU486 and the antiestrogen ICI 182,780 on cadherin-11 mRNA and protein expression levels in human endometrial stromal cells undergoing decidualisation in vitro. RU486 decreased the levels of the cadherin-11 mRNA transcript and protein species present in these cell cultures in a dose- and time-dependent manner. Similarly, ICI 182,780 was capable of reducing stromal cadherin-11 mRNA and protein expression levels in a dose-dependent manner, suggesting that the progesterone-mediated increase in cadherin-11 expression levels in human endometrial cells undergoing decidualisation in vitro is dependent on the presence of estrogens. Cadherin-11 expression levels also were reduced in endometrial stromal cell cultures subjected to progesterone withdrawal, an in vitro model for menstrual breakdown. These studies not only give us useful insight into the mechanism(s) by which progesterone regulates stromal cadherin-11 expression, but they strengthen our hypothesis that this cell adhesion molecule plays a central role in the remodeling processes that occur in the human endometrium in response to fluctuations in the levels of gonadal steroids.

Identification of progesterone-dependent messenger ribonucleic acid regulatory patterns in the rhesus monkey endometrium by differential-display reverse transcription-polymerase chain reaction

We used differential-display reverse transcription-polymerase chain reaction (DDRT-PCR) to identify different patterns of progesterone (P4)-dependent gene regulation in rhesus monkey endometria. Complementary DNA populations representing the proliferative phase (estrogen dominant, EcDNA) and an inadequate secretory phase (low level of P4, IcDNA) were compared with a cDNA population representing an adequate secretory phase (normal level of P4, PcDNA). We were able to distinguish four different levels of mRNA regulation: 1) up-regulation by P4 during an adequate secretory phase, 2) autologous down-regulation (IcDNA versus PcDNA), 3) lower abundance in IcDNA compared to PcDNA, and 4) P4-dependent inhibition of EcDNA gene expression. We isolated and sequenced 16 fragments representing these different levels of P4 regulation. The sequence of three fragments that were autologously down-regulated (I1, I2, I4) matched previously entered GenBank mRNAs: I1 encodes serine/threonine protein phosphatase A; I2 encodes oxobutanoate dehydrogenase E1b-beta; and I4 encodes line-1 reverse transcriptase homologue. Six other fragments exhibited homology to uncharacterized expressed sequence tags, sequence site tags, and cosmid clones. The remaining seven fragments exhibited no significant homology to GenBank entries at this time. The various patterns of P4-dependent gene regulation identified in the present study are likely to play roles in the temporal orchestration of events that lead to proper maturation of the endometrium.