Invasion Of Placental Trophoblast Cells Research Articles

Growth differentiation factor myostatin regulates epithelial-mesenchymal transition genes and enhances invasion by increasing serine protease inhibitors E1 and E2 in human trophoblast cells.

Placental insufficiency disorders, including preeclampsia and intrauterine growth restriction, are major obstetric complications that can have devastating effects on both the mother and the fetus. These syndromes have underlying poor placental trophoblast cell invasion into uterine tissues. Placental invasion is controlled by many hormones and growth factors. Myostatin (MSTN) is a transforming growth factor-β superfamily member recognized for its important role in muscle growth control. MSTN has also been shown to be secreted and functioning in the placenta, and its serum and/or placental levels were found to be upregulated in preeclampsia and intrauterine growth restriction. Considering that the mechanistic role of MSTN in placentation remains poorly understood, we hypothesized that MSTN uses ALK4/5-SMAD2/3/4 signaling to increase human trophoblast invasion through a group of epithelial-mesenchymal transition genes including SERPINE2, PAI-1, and SOX4. mRNA sequencing of control and MSTN-treated primary human trophoblast cells (n = 5) yielded a total of 610 differentially expressed genes (false discovery rate <0.05) of which 380 genes were upregulated and 230 were downregulated. These differentially expressed genes were highly enriched in epithelial-mesenchymal transition genes, and a subset including SERPINE2, PAI-1, and SOX4 was investigated for its role in MSTN-induced trophoblast cell invasion. We found that MSTN induced upregulation of SERPINE2 via ALK4/5-SMAD2/3/4 signaling; however, SMAD2 was not involved in MSTN-induced PAI-1 upregulation. SOX4 was involved in MSTN-induced upregulation of SERPINE2, but not PAI-1. Collectively, this study discovers novel molecular mechanisms of MSTN-induced human trophoblast cell invasion and provides insight into the functional consequences of its dysregulation in placental insufficiency disorders.

Pseudogene CLEC4GP1 modulates trophoblast cell apoptosis and invasion via IL-15 inhibition

Preeclampsia (PE) is a pregnancy-associated complication accompanied by gestational hypertension and proteinuria, affecting 2–8% of pregnancies globally. The placental trophoblast cell invasion of decidua and myometrium during early gestation is crucial for healthy placentation. Thus, trophoblast dysfunction might contribute to PE onset. Therefore, further investigations are needed to elucidate the underlying mechanism of trophoblast cell functions. In the present study, we identified a novel pseudogene named C-Type Lectin Domain Family 4 Member G Pseudogene 1 (CLEC4GP1), which was aberrantly expressed in PE placental tissues. In vitro analyses showed that CLEC4GP1 overexpression significantly increased the cell viability and invasiveness and decreased the apoptosis rate of HTR-8/SVneo and JEG-3 cells, while CLEC4GP1 knockdown exerted opposite effects, suggesting the beneficial role of CLEC4GP1 in trophoblast cells. Next, co-expression analysis found that CLEC4GP1 was negatively correlated with Interleukin 15 (IL-15). The expression of IL-15 dramatically increased in PE placental tissues. In HTR-8/SVneo and JEG-3 cells, IL-15 exhibited detrimental effects, opposite to CLEC4GP1, and they were negatively correlated. In addition, CLEC4GP1 attenuates the mRNA stability of IL-16 by inhibiting the binding between human antigen R (HuR) protein and IL-15 RNA. Finally, the obverse effects of CLEC4GP1 and IL-15 were investigated, and results showed that IL-15 reverted CLEC4GP1 induced cellular functions. In brief, these data suggest that CLEC4GP1/IL-15 axis might modulate the occurrence and progression of PE via influencing the trophoblast cell viability, apoptosis, and invasive capability. This study provided cognizance of targeting the CLEC4GP1/IL-15 axis as a novel therapeutic approach to mitigate PE progression.

The Mechanism of Downregulation of Twist1 Inhibiting Trophoblast Invasion and Aggravating the Development of Preeclampsia.

To study the expression of under expressed transcription factor Twist1 in preeclampsia (PE) and its effect on the invasion of placental trophoblast cells and to explore its related mechanism on the development of PE by establishing a pregnant rat model. Methods: the villi were collected from the induced abortion in the first trimester (6–8 weeks), the normal placenta (18–20 weeks) induced by the second trimester, the term placenta tissue of normal pregnancy (37–40 weeks), and the placental tissue of patients with PE, to detect the expression of Twist1. Trophoblast cells were subjected to primary culture in placental tissues of normal pregnant women and placental tissues of PE patients. The invasion ability of the two groups of trophoblasts was detected, and the primary cultured trophoblasts were divided into two groups: an experimental group and a control group. Specific Twist1 siRNA was added to the experimental group, and no reagents were added to the control group. The above-mentioned cells were given different interventions. To explore the effect of Twist1 on trophoblast cell invasion, cells were cultivated for 72 h. The SD rats were conceived. After the pregnancy was stable, the SD rats in different groups were treated with different treatments (interference with Twist1), and the average systolic blood pressure and urine protein of the gestational mothers in the different treatment groups were measured at 1 week, 2 weeks, and full-term pregnancy. The expression of Twist1 in the placenta tissue of SD rats with different interventions at full-term pregnancy was detected. The results showed that Twist1 expression is down-regulated in PE, and the invasion ability of placental trophoblast cells in PE patients is weak. After inhibiting Twist1, the mean tail artery pressure and urine protein level of SD pregnant rats increase, showing a trend of PE. The mechanism may be related to the inhibition of the placenta by Twist1 Trophoblast cell invasion.

Myostatin increases human trophoblast cell invasion by upregulating N-cadherin via SMAD2/3-SMAD4 signaling

Placental insufficiency disorders are major obstetric complications that share a common phenomenon of poor placental trophoblast cell invasion and remodeling of uterine tissues. Myostatin is a transforming growth factor (TGF)-β superfamily member well known for its important role in muscle growth control. Myostatin is also produced in the placenta and has been shown to regulate some trophoblast functions. However, its roles in placental development are still poorly understood. In this study, we tested the hypothesis that myostatin increases trophoblast cell invasion by upregulating N-cadherin via SMAD2/3-SMAD4 signaling. Primary and immortalized (HTR8/SVneo) trophoblast cells were used as study models. Matrigel-coated transwell invasion assays were used to study the effects of recombinant human myostatin on trophoblast cell invasion. Reverse transcription quantitative real-time polymerase chain reaction and Western blot were used to measure myostatin effects on N-cadherin mRNA and protein levels, respectively. Small inhibitor molecules as well as siRNA-mediated knockdown were used to block myostatin receptor and downstream signaling, respectively. Data were analyzed either by unpaired Student T test or one-way analysis of variance followed by Newman Keuls test for multiple group comparisons. Myostatin significantly increased primary and HTR8/SVneo trophoblast cell invasion. Moreover, myostatin upregulated N-cadherin mRNA and protein levels in a time-dependent manner in both study models. These effects were blocked by inhibition of TGF-β type I receptors as well as siRNA-mediated knockdown of SMAD2/3 combined or common SMAD4. Importantly, myostatin-induced trophoblast cell invasion was abolished by knockdown of N-cadherin, SMAD2/3, or SMAD4. Myostatin may increase human trophoblast cell invasion by upregulating N-cadherin via SMAD2/3-SMAD4 signaling.

Dysregulated BMP2 in the Placenta May Contribute to Early-Onset Preeclampsia by Regulating Human Trophoblast Expression of Extracellular Matrix and Adhesion Molecules

Many pregnancy disorders, including early-onset preeclampsia (EOPE), are associated with defects in placental trophoblast cell invasion and differentiation during early placental development. Bone morphogenetic protein 2 (BMP2) belongs to the TGF-β superfamily and controls various physiological and developmental processes. However, the expression of BMP2 in the placenta and underlying molecular mechanisms of how BMP2 regulates trophoblast function remain unclear. In this study, we analyzed several publicly available microarray and RNA-seq datasets and revealed differences in expression of TGF-β superfamily members between gestational age-matched non-preeclamptic control and EOPE placentas. Importantly, BMP2 levels were significantly reduced in EOPE placentas compared with controls, and RNAscope in situ hybridization further demonstrated BMP2 expression was disrupted in EOPE placental villi. To explore the molecular mechanisms of BMP2-regulated early trophoblast differentiation, we examined BMP2 expression in first-trimester human placenta and found it to be localized to all subtypes of trophoblasts and the decidua. RNA-seq analysis on control and BMP2-treated primary human trophoblast cells identified 431 differentially expressed genes, including several canonical TGF-β/BMP signaling targets (BAMBI, ID1, INHBA, IGFBP3). Gene ontology annotations revealed that differentially expressed genes were involved in cell adhesion and extracellular matrix organization. Furthermore, we identified adhesion molecule with IgG-like domain 2 (AMIGO2) as a novel target for BMP2 that contributed to BMP2-induced trophoblast invasion and endothelial-like tube formation. Overall, our findings provide insight into the molecular processes controlled by BMP2 during early placental development that may contribute to the pathogenesis of EOPE.

GDF-8 stimulates trophoblast cell invasion by inducing ALK5-SMAD2/3-mediated MMP2 expression.

Matrix metalloproteinases (MMPs) play a pivotal role in the regulation of cell invasion. Placental trophoblast cell invasion is a precisely regulated event. Dysregulation of MMPs has been linked to various placental diseases. Growth differentiation factor-8 (GDF-8), also known as myostatin, is a member of the transforming growth factor-beta (TGF-β) superfamily. GDF-8 and its putative receptors are expressed in human extravillous cytotrophoblast cells (EVTs). Although the pro-invasive effect of GDF-8 in human EVT cells has been recently reported, the underlying molecular mechanism remains largely unknown. In this study, we investigate the effects of GDF-8 on the expression of the two most important MMPs, MMP2 and MMP9, in the HTR-8/SVneo human EVT cell line. Our results show that GDF-8 significantly upregulates the expression of MMP2. The expression of MMP9 is not affected by GDF-8. Using a siRNA-mediated knockdown approach, we reveal that the stimulatory effect of GDF-8 on MMP2 expression is mediated by the ALK5-SMAD2/3 signaling pathway. Additionally, the knockdown of MMP2 attenuates the GDF-8-induced cell invasiveness. These findings deepen our understanding of the biological roles of GDF-8 in the regulation of human trophoblast cell invasion.

Differential Expression of Rab5 and Rab7 Small GTPase Proteins in Placental Tissues From Pregnancies Affected by Maternal Coronavirus Disease 2019

PurposeThe majority of pregnancies affected by maternal coronavirus disease 2019 (COVID-19) do not result in fetal transmission. However, several studies have identified parenchymal changes in their placental tissues, suggesting a placental response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the maternal–fetal interface. Although many COVID-19 placental studies have focused on the expression of the canonical SARS-CoV-2 entry proteins angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2, further characterization of subcellular molecules involved in viral trafficking have not yet been investigated in these tissues. Of interest are Rab proteins, a family of small GTPase proteins that direct intracellular transport between different endocytic organelles. Rab5 and Rab7 in particular have previously been implicated in HIV and cytomegalovirus invasion of placental trophoblast cells in vitro; the localization of these molecules has not been fully characterized within the human maternal–fetal interface, however, or within placental tissues from SARS-CoV-2–infected pregnancies. MethodsUsing fluorescent immunohistochemistry, Rab5 and Rab7 placental localization and comparative fluorescence intensity were explored in a cohort of placental tissues from pregnancies affected by maternal COVID-19 disease (COVID, n = 15) compared with contemporary control subjects (Control, n = 10). Fluorescence intensity was quantified by using corrected total cell fluorescence values. FindingsWithin placental villi, Rab5 was consistently localized in syncytiotrophoblast and cytotrophoblast cells. Rab5 had significantly higher mean (SEM) fluorescence intensity in the COVID cohort (Control, 1.96 [0.16]; COVID, 2.62 [0.09]; P = 0.0014). In contrast, although Rab7 was also localized within placental villous syncytiotrophoblast and cytotrophoblast cells, mean (SEM) Rab7 fluorescence intensity was significantly downregulated in COVID vs Control placentas (Control, 35.9 [4.1]; COVID, 20.1 [0.52]; P = 0.0001). ImplicationsThis differential expression of Rab5 and Rab7 suggests that placental endocytic pathways may be altered at the maternal–fetal interface in pregnancies affected by maternal SARS-CoV-2 infection. As key molecules governing intracellular vesicle transport, including viral trafficking, Rab GTPase proteins may be of interest for ongoing studies examining placental responses to COVID-19 in pregnancy.

LncRNA PROX1-AS1 mediates the migration and invasion of placental trophoblast cells via the miR-211-5p/caspase-9 axis

ABSTRACT Preeclampsia (PE) is a potentially fatal pregnancy complication; however, its pathogenesis remains unclear. Long non-coding RNAs (lncRNAs) are associated with occurrence and progression of PE. Therefore, this study aimed to explore the function of the lncRNA prospero homeobox 1-antisense RNA 1 (PROX1-AS1) and elucidate its underlying molecular mechanism of action. We found that the expression levels of PROX1-AS1 were elevated in both the placental tissues and blood samples of the patients with PE. Moreover, the results of the flow cytometry and transwell assay showed that the knockdown of PROX1-AS1 inhibited the apoptosis and promoted the migration and invasion of HTR-8/SVneo cells. We also assessed the interactions between PROX1-AS1, caspase-9, and microRNA (miR)-211-5p via dual-luciferase reporter and RNA pull-down analyses. The data indicated that PROX1-AS1 acted as a sponge for miR-211-5p to regulate the expression of caspase-9. Moreover, the expression of miR-211-5p was reduced in PE and negatively related to PROX1-AS1, while that of caspase-9 was increased in PE and negatively regulated by miR-211-5p. Furthermore, inhibition of miR-211-5p rescued the facilitation of cell apoptosis, migration and invasion induced by the knockdown of PROX1-AS1. We also found that caspase-9 improved the apoptosis rate, and suppressed the cell migration and invasion induced by the overexpression of miR-211-5p. In conclusion, the knockdown of PROX1-AS1 promoted the cell morbidity of the trophoblast cells by modulating the miR-211-5p/caspase-9 axis, which may alleviate the progression of PE. This novel regulatory network may contribute to the pathogenesis and progression of PE.

Role of Human Leukocyte Antigens at the Feto-Maternal Interface in Normal and Pathological Pregnancy: An Update.

The successful maternal tolerance of the semi-allogeneic fetus provides an apparent immunologic paradox. Indeed, deep invasion of placental trophoblast cells into maternal uterine tissue and the following growth of the fetus have to be tolerated by a pregnant woman’s immune system. Among the various possible protective mechanisms that may be involved in human pregnancy, the expression of a non-classical pattern of human leukocyte antigen (HLA) class I molecules and the complete lack of expression of HLA class II molecules in placental tissues seem to be the most relevant mechanisms of fetal escape from maternal immune recognition. The importance of HLA molecules in fetal toleration by the maternal immune system is highlighted by pregnancy complications occurring in cases of abnormal HLA molecule expression at the maternal–fetal interface. In this review, we summarize evidences about the role of placental HLA molecules in normal and pathological pregnancies.

MiR-214-5p suppresses the proliferation, migration and invasion of trophoblast cells in pre-eclampsia by targeting jagged 1 to inhibit notch signaling pathway

MicroRNA-214-5p has been reported to be expressed in placental tissue and suppressed the proliferation and invasion of various tumor cells. However, the role of miR-214-5p in pre-eclampsia has not been reported. We aimed to explore the effects of miR-214-5p in proliferation, migration, and invasion of placental trophoblast cells. RT-qPCR was used to quantify the miR-214-5p expression level in placental samples and four types of trophoblast cell lines. Cell proliferation was monitored by CCK-8 and Edu staining assays. Flow cytometry was used to determine the cell cycle. Wound healing and transwell assays were performed to measure the migratory and invasive capacities in JEG-3 and BEWO cells. In addition, we investigated whether miR-214-5p targeted Jagged 1 to regulate the Notch signaling pathway to affect trophoblast cells by luciferase assay and western blot. The expression of miR-214-5p was significantly increased in the placenta of patients with PE. Moreover, the proliferation, migration, and invasion of JEG-3 cells transfected with miR-214-5p mimic were inhibited. The results were reversed when BEWO cells were transfected with miR-214-5p inhibitor. The dual-luciferase assay demonstrated that miR-214-5p directly regulated Jagged 1. The expression of the proteins associated with the Notch signaling pathway, Jagged 1, Notch 1, HEY 1 and HES 1 were all decreased when Jagged 1 was negatively regulated by miR-214-5p. miR-214-5p directly down-regulated Jagged 1 expression, then suppressed proliferation, migration, and invasion of human placental trophoblast cells by inhibiting the Notch signaling pathway.

Zinc improves learning and memory abilities of fetal growth restriction rats and promotes trophoblast cell invasion and migration via enhancing STAT3-MMP-2/9 axis activity.

Fetal growth restriction (FGR) is a well-known risk factor for cognitive dysfunction, especially for learning and memory abilities. However, knowledge about prevention and treatment methods of learning and memory abilities of fetal are limit. Here, Morris water maze and passive avoidance tests showed zinc supplementation could protect the impairment of the learning and memory abilities caused by FGR. As accumulating evidence suggested that insufficiency of placental trophoblast cell invasion was closely related to FGR fetal neurodevelopmental dysplasia, we further explored the relationship between zinc supplementation during pregnancy and placental trophoblast. Microarray identified 346 differently expressed genes in placental tissues with and without zinc supplementation, and GO and KEGG analyses showed these differently expressed genes were highly enriched in cell invasion and migration and STAT3 pathway. Protein-protein interaction(PPI) analysis found that STAT3 interacted with matrix metalloproteinase-2/9 (MMP-2/9). In vivo, western blot results authenticated that the expression levels of phospho-STAT3, STAT3, MMP-2 and MMP-9 were up-regulated in placental tissues after zinc treatment. To validate whether zinc could promotes trophoblast cell invasion and migration via enhancing STAT3-MMP-2/9 activity. In vitro, Transwell assay was performed, and we observed that abilities of invasion and migration were obviously increased in zinc treated trophoblast cells. And phospho-STAT3, STAT3, MMP-2 and MMP-9 expression levels were correspondingly increased in zinc treated trophoblast cells, which were dose-dependent. Moreover, gain–of-function and loss-of-function of STAT3 confirmed that zinc promotes cell invasion and migration via regulating STAT3 mediated up-regulation of MMP-2/9 activity. We propose that activation of MMP-2/9 mediated by STAT3 may contribute to invasion and migration of trophoblast cells, which improved neurodevelopmental impairment of FGR rats probably via contributing to placental development. Our findings are the first to show a possible mechanism of reversing neurodevelopmental impairment of FGR rats by zinc supplementation, holding promise for the development of novel therapeutic modalities for learning and memory abilities impairment caused by FGR.

Lymphocyte immunization therapy: Role in Repeated Miscarriages & Implantation Failure

The successful maternal tolerance of the semiallogeneic fetus provides an apparent immunologic paradox. Deep invasion of placental trophoblast cells into maternal uterine tissue requires tolerance of the mother’s immune system. The expression of a nonclassical pattern of human leukocyte antigen (HLA) class I molecules and the complete lack of expression of HLA class II molecules in placental tissues are the most relevant mechanisms of fetal escape from maternal immune recognition. The importance of HLA molecules in fetal tolerance by the maternal immune system is clearly demonstrated by pregnancy complications occurring in cases of abnormal HLA molecule expression at the maternal–fetal interface. In this chapter, we summarize recent evidence about the role of placental HLA molecules in normal pregnancy and how abnormal expression of HLA molecules might contribute to the pathogenesis of recurrent pregnancy loss and implantation failures.

Regulation of caspase-3 expression to maintain fetal growth in Porphyromonas gingivalis-infected pregnant rats

Periodontal disease has been involved in a variety of systemic disorders and suspected as a potential risk factor for fetal growth restriction. Periodontal pathogenic bacteria may actively regulate embryonic development, implantation and placental trophoblast cell invasion. This study aimed to analyze the role of TNF-α, IL-10 and caspase-3 to maintain fetal growth in Porphyromonasgingivalis-infected pregnant rats. Female rats were infected with live-Porphyromonas gingivalis at concentration of 2x109 cells/ml into subgingival sulcus area of the maxillary first molar before and during pregnancy. They were sacrificed on gestational day (GD)-14 and GD20. The weight and length of placentas and fetuses were evaluated. The expression of TNF-α, IL-10 and caspase-3 in macrophages and trophoblast cells were detected by immunohistochemistry. On GD14, TNF-α (R2=0.416;P=0.000) and IL-10 (R2=0.187;P=0.012) had an important role to increase expression of caspase-3 in the placenta, but only TNF-α (R2=0.393;P=0.000 ) was able to increase the expression of caspase-3 on GD20. TNF-α and caspase-3 also had an important role (P&lt;0.000) to decrease fetal weight, fetal length and placental weight on GD14 and GD20, but it was not the case with IL-10 (P&gt;0.000). The increasing expressions of TNF-α and IL-10 did not only enhance immune protection, but also maintained the trophoblast cells survival by regulating expression of caspase-3. Porphyromonas gingivalis infection in maternal periodontal tissue can lead to decrease in placental weight, fetal weight and fetal length which mediated by increasing expression of TNF-α, IL-10 and caspase-3 in the placenta.

Regulation of caspase-3 expression to maintain fetal growth in Porphyromonas gingivalis-infected pregnant rats

&lt;p&gt;Periodontal disease has been involved in a variety of systemic disorders and suspected as a potential risk factor for fetal growth restriction. Periodontal pathogenic bacteria may actively regulate embryonic development, implantation and placental trophoblast cell invasion. This study aimed to analyze the role of TNF-α, IL-10 and caspase-3 to maintain fetal growth in &lt;em&gt;Porphyromonas&lt;/em&gt;&lt;em&gt; gingivalis&lt;/em&gt;-infected pregnant rats. Female rats were infected with live-&lt;em&gt;Porphyromonas gingivalis&lt;/em&gt; at concentration of 2x10&lt;sup&gt;9&lt;/sup&gt; cells/ml into subgingival sulcus area of the maxillary first molar before and during pregnancy. They were sacrificed on gestational day (GD)-14 and GD20. The weight and length of placentas and fetuses were evaluated. The expression of TNF-α, IL-10 and caspase-3 in macrophages and trophoblast cells were detected by immunohistochemistry. On GD14, TNF-α (R&lt;sup&gt;2&lt;/sup&gt;=0.416;&lt;em&gt;P&lt;/em&gt;=0.000) and IL-10 (R&lt;sup&gt;2&lt;/sup&gt;=0.187;&lt;em&gt;P&lt;/em&gt;=0.012) had an important role to increase expression of caspase-3 in the placenta, but only TNF-α (R&lt;sup&gt;2&lt;/sup&gt;=0.393;&lt;em&gt;P&lt;/em&gt;=0.000 ) was able to increase the expression of caspase-3 on GD20. TNF-α and caspase-3 also had an important role (&lt;em&gt;P&lt;/em&gt;&amp;lt;0.000) to decrease fetal weight, fetal length and placental weight on GD14 and GD20, but it was not the case with IL-10 (&lt;em&gt;P&lt;/em&gt;&amp;gt;0.000). The increasing expressions of TNF-α and IL-10 did not only enhance immune protection, but also maintained the trophoblast cells survival by regulating expression of caspase-3. &lt;em&gt;Porphyromonas&lt;/em&gt;&lt;em&gt; gingivalis&lt;/em&gt; infection in maternal periodontal tissue can lead to decrease in placental weight, fetal weight and fetal length which mediated by increasing expression of TNF-α, IL-10 and caspase-3 in the placenta.&lt;/p&gt;

RhoGDI2 Is Expressed in Human Trophoblasts and Involved in Their Migration by Inhibiting the Activation of RAC11

The invasion of placental trophoblast cells into the maternal decidua is an essential aspect of placental embedment. The process of placentation bears several striking similarities to tumor cell metastasis. However, trophoblastic migration during implantation and placentation is stringently controlled both in space and time. RhoGDI2 belongs to a family of Rho guanosine diphosphate dissociation inhibitors (RhoGDIs), and RhoGDI2 is a metastasis suppressor gene and a marker of aggressive human cancer. We evaluated whether RhoGDI2 has a physiological role in embryo implantation, particularly trophoblast migration. The mRNA and protein expression levels of RhoGDI2 were higher in term placentas compared with first-trimester placentas as detected by real-time PCR and Western blot. Immunohistochemical studies indicated that RhoGDI2 localized to the cytotrophoblast layer and extravillous trophoblast in first-trimester placentas and was distributed in the syncytiotrophoblast layers of term placentas. Overexpression of RhoGDI2 in HTR-8/SVneo cells was associated with reduced RAC1-guanosine triphosphate (GTP) levels and inhibited cell migration. Conversely, small interfering RNA-mediated downregulation of RhoGDI2 resulted in significantly increased RAC1-GTP levels. Altered RhoGDI2 expression had no significant effects on cell proliferation. In conclusion, RhoGDI2 inhibits trophoblast cell migration, and this function may involve suppression of RAC1 activation.

Abstract 3257: Nodal signalling in choriocarcinoma cells

Abstract Choriocarcinoma is an aggressive cancer that arises when the invasion of placental trophoblast cells into the endometrium becomes dysregulated. Trophoblast invasion is a complex phenomenon, dependent on cues that drive trophoblast invasion, as well as factors to ensure that placental invasion does not extend beyond the myometrium. Nodal, a member of the TGF-β superfamily, is expressed throughout the endometrium during the peri-implantation period and in invasive trophoblast cells. However, Nodal's exact role in placental function is unclear. Nodal signals by activating the ALK4/7, ActRIIB and Cripto-1 receptor complex and emerging evidence suggests that its signalling strength can be controlled at the level of receptor endocytosis into signaling endosomes. Two key regulators of receptor endocytosis and cell invasion are the α-arrestins, multifunctional scaffolding proteins and Ral GTPases, members of the Ras superfamily. Ral can bind to ActRIIB, and its activity can be regulated by Ras, as well as by α-arrestins, in a Ras-independent manner. We thus hypothesized that Nodal promotes trophoblast invasion via a α-arrestin/Ral-mediated pathway. The specific objectives of my study are to (i) determine the effects of Nodal on trophoblast invasion, (ii) elucidate a role for α-arrestin / Ral signaling in regulating Nodal-induced trophoblast invasion. We found that Nodal stimulates the invasion of both the non-malignant HTR-8SV/neo trophoblast and JAR choriocarcinoma cells using Matrigel-coated transwell chamber assays. Interestingly, we found that the JAR choriocarcinoma cells responded differently to Nodal in that while HTR-8SV/neo invasion returned to baseline levels, JAR choricocarcinoma cells continued to invade even at the higher concentrations of Nodal (100ng/mL &amp; 500ng/mL). For this reason, we decided to look at potential differences in the regulation of Nodal-induced invasion between the non-malignant HTR-8SV/neo trophoblast and JAR choricoarcinoma cell lines. We found that the JAR choriocarcinoma cells differentially expressed Ral and α-arrestin proteins compared to the HTR-8SV/neo cells. Additonally, endogenous Ral and α-arrestins associate with the ALK4 and 7 receptors, and knockdown of these molecules impaired Nodal-induced invasion. Thus, our data reveal a novel function for Nodal in modulating trophoblast invasion via a α-arrestin/Ral signaling pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3257. doi:1538-7445.AM2012-3257