Activation of beta-catenin signalling increases StarD7 gene expression in JEG-3 cells

SUMO1 degrader induces ER stress and ROS accumulation through deSUMOylation of TCF4 and inhibition of its transcription of StarD7 in colon cancer

Small molecule degraders of small ubiquitin-related modifier 1 (SUMO1) induce SUMO1 degradation in colon cancer cells and inhibits the cancer cell growth; however, it is unclear how SUMO1 degradation leads to the anticancer activity of the degraders. Genome-wide CRISPR-Cas9 knockout screen has identified StAR-related lipid transfer domain containing 7 (StarD7) as a critical gene for the degrader's anticancer activity. Here, we show that both StarD7 mRNA and protein are overexpressed in human colon cancer and its knockout significantly reduces colon cancer cell growth and xenograft progression. The treatment with the SUMO1 degrader lead compound HB007 reduces StarD7 mRNA and protein levels and increases endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) production in colon cancer cells and three-dimensional (3D) organoids. The study further provides a novel mechanism of the compound anticancer activity that SUMO1 degrader-induced decrease of StarD7 occur through degradation of SUMO1, deSUMOylation and degradation of T cell-specific transcription 4 (TCF4) and thereby inhibition of its transcription of StarD7 in colon cancer cells, 3D organoids and patient-derived xenografts (PDX).

Integrated Bioinformatic Analysis of Competing Endogenous RNA Network of Choriocarcinoma

Background

Numerous studies have demonstrated that noncoding RNAs are involved in choriocarcinoma (CC). The competing endogenous RNA (ceRNA) network plays an important role in the occurrence and development of carcinoma. However, the involvement of the ceRNA network in CC remains unclear. The current study aimed to investigate the regulatory mechanism of ceRNA in CC.

Material/Methods

We downloaded the messenger RNAs (mRNAs) expression profiles (GSE20510 and GSE65654) and microRNAs (miRNAs) expression profiles (GSE32346 and GSE130489) from GEO datasets. The limma package of R software was used to identify differentially expressed RNAs (DERNAs). Then, we performed functional annotation of the differentially expressed mRNAs (DEmRNAs). TargetScan, miRDB, miRWalk, and Starbase were used to construct a CC-specific ceRNA network and select key molecules.

Results

The results identified a total of 177 DEmRNAs and 189 differentially expressed miRNAs (DEmiRNAs) between the trophoblast and CC cell line samples. Ten differentially expressed lncRNAs (DElncRNAs) were obtained based on experimental studies. The DEmRNAs were mainly enriched in cell proliferation, positive regulation of the apoptotic process, and cell death. A total of 10 genes were ascertained as hub genes. Based on DEmRNAs, DEmiRNAs, and DElncRNAs, a CC-specific ceRNA network was established. Five DElncRNAs, 15 DEmiRNAs, and 45 DEmRNAs were identified. In addition, LINC00261, MEG3, MALAT1, H19, and OGFRP1 were identified as 5 key lncRNAs in choriocarcinoma.

Conclusions

This study provides novel insights into CC mechanisms and identified potential therapeutic targets for CC.

Phytanoyl-CoA 2-Hydroxylase-Interacting Protein-Like Gene Is a Therapeutic Target Gene for Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common primary CNS cancer and has a poor prognosis. This study searched for significant genes and the mechanisms involved in GBM. We used the Gene Expression Omnibus (GEO) to test the WHO normal and IV glioma database, used R tool to identify the significant gene, and finally, combined these with The Cancer Genome Atlas (TCGA) to verify the significant genes. Subsequently, we explored the biological mechanisms involved. Phytanoyl-CoA 2-hydroxylase-interacting protein-like gene (PHYHIPL) is downregulated in grade IV glioma (GBM). The downregulation of PHYHIPL in GBM is accompanied by poor overall survival in the TCGA database, which indicates that PHYHIPL is a protection gene in GBM development. Bioinformatics analysis shows that the poor prognosis with downregulated PHYHIPL may be the result of the TNF signaling pathway and the IL-17 signaling pathway, but good prognosis accompanied by upregulated PHYHIPL may be the result of retrograde endocannabinoid signaling and the cAMP signaling pathway. Protein-protein interactions (PPI) net indicated that PHYHIPL may play a vital role in cell metabolism, and we hypothesize that the downregulation mechanism may be the result of mutations of the ß-catenin gene and the endogenous siRNA, as shown in previous studies. PHYHIPL may be a target gene for the treatment and prognosis of GBM.

Hexosamine pathway regulates StarD7 expression in JEG-3 cells

StarD7 is a lipid binding protein involved in the delivery of phosphatidylcholine to the mitochondria whose promoter is activated by Wnt/β-catenin signaling. Although the majority of glucose enters glycolysis, ~ 2-5% of it can be metabolized via the hexosamine biosynthetic pathway (HBP). Considering that HBP has been implicated in the regulation of β-catenin we explored if changes in glucose levels modulate StarD7 expression by the HBP in trophoblast cells. We found an increase in StarD7 as well as in β-catenin expression following high-glucose (25 mM) treatment in JEG-3 cells; these effects were abolished in the presence of HBP inhibitors. Moreover, since HBP is able to promote unfolded protein response (UPR) the protein levels of GRP78, Ire1α, calnexin, p-eIF2α and total eIF2α as well as XBP1 mRNA was measured. Our results indicate that a diminution in glucose concentration leads to a decrease in StarD7 expression and an increase in the UPR markers: GRP78 and Ire1α. Conversely, an increase in glucose is associated to high StarD7 levels and low GRP78 expression, phospho-eIF2α and XBP1 splicing, although Ire1α remains high when cells are restored to high glucose. Taken together these findings indicate that glucose modulates StarD7 and β-catenin expression through the HBP associated to UPR, suggesting the existence of a link between UPR and HBP in trophoblast cells. This is the first study reporting the effects of glucose on StarD7 in trophoblast cells. These data highlight the importance to explore the role of StarD7 in placenta disorders related to nutrient availability.

EFFECTS OF Wnt / β-CATENIN SIGNALING PATHWAY AND STAR D7 ON TESTOSTERONE SYNTHESIS

BACKGROUND

This study aimed to assess the mechanism through which Wnt/ beta - catenin signaling pathway, and StarD7, prometes testosterone synthesis, and to explore a new pathway for the regulation of testosterone synthesis.

ANIMALS AND METHODS

Leydig cells were isolated from male Sprague-Dawley rats divided into four groups and treated with Annexin 5 in concentration of 0, 0.1, 1 and 10 nmol/L. Testosterone secretion, expression of StarD7, StarD7 mRNA, β-catenin and changes of β - catenin localization in Leydig cells of testis of rats were tested in the four groups.

RESULTS

mRNA and protein levels of StarD7 and β-catenin increased significantly, upon stimulation with 1 nmol/L annexin 5. Accumulation of β-catenin inside the cells and the nucleus, was observed by immunofluorescence staining, in cells treated with annexin 5. These findings indicate a possible role of StarD7 and β-catenin in the process of annexin5-mediated stimulation of testosterone synthesis.

CONCLUSIONS

Wnt/β-catenin signaling pathway and StarD7 are involved in the process of annexin5 stimulation of testosterone synthesis. Activation of Wnt/ β-catenin signaling pathway by Annexin5, and increase in StarD7 expression lead to elevated expression of key regulatory enzymes in testosterone synthesis, thus promoting testosterone synthesis.

The role of SATB1 in HTR8/SVneo cells and pathological mechanism of preeclampsia

OBJECTIVE

Special AT-rich sequence binding protein 1 (SATB1) play potential roles in invasion and metastasis of tumor cells, and involves in human placental and fetal development. The objective of this study is to explore the role of SATB1 in migration and invasion of trophoblast and the potential mechanism.

METHODS

Human placental tissues from first trimester, second trimester, term, and preeclampsia (PE) pregnancies were used to detect the expression and subcellular location of SATB1 and β-catenin. The human trophoblast cell line HTR8/SVneo, which was treated with hypoxia/re-oxygenation (H/R), lithium chloride (LiCl) or SATB1-siRNA to investigate the role of SATB1 and β-catenin signaling in human trophoblast function.

RESULTS

We observed that SATB1 specifically localized within trophoblast cells of placenta tissues. Gradually reduced expression of SATB1 was observed during gestation, and lower expression were detected in placenta of PE compared with normal pregnancy. Moreover, the expression of SATB1 was decreased in H/R-treated HTR8/Svneo cells and villous explants. The Wnt/β-catenin signaling pathway interacted with SATB1 expression and H/R treatment resulted in Wnt pathway inhibition in trophoblast, while lithium chloride (LiCl) treatment enhanced H/R-exposed HTR8/SVneo migration and invasion. Knockdown of SATB1 significantly reduced the level of β-catenin and the migratory and invasive abilities of trophoblast.

CONCLUSIONS

Our data suggested that oxidative stress reduced SATB1 leading to inhibition of Wnt/β-catenin, and participate in the subdued migration and invasion of trophoblast, which indicated a potential pathological mechanism of PE.

Role of Wnt signalling in early pregnancy

The integration of a complex network of signalling molecules promotes implantation of the blastocyst and development of the placenta. These processes are crucial for a successful pregnancy and fetal growth and development. The signalling network involves both cell-cell and cell-extracellular matrix communication. The family of secreted glycoprotein ligands, the Wnts, plays a major role in regulating a wide range of biological processes, including embryonic development, cell fate, proliferation, migration, stem cell maintenance, tumour suppression, oncogenesis and tissue homeostasis. Recent studies have provided evidence that Wnt signalling pathways play an important role in reproductive tissues and in early pregnancy events. The focus of this review is to summarise our present knowledge of expression, regulation and function of the Wnt signalling pathways in early pregnancy events of human and other model systems, and its association with pathological conditions. Despite our recent progress, much remains to be learned about Wnt signalling in human reproduction. The advancement of knowledge in this area has applications in the reduction of infertility and the incidence and morbidity of gestational diseases.

Oxidative stress-induced C/EBPβ inhibits β-catenin signaling molecule involving in the pathology of preeclampsia

INTRODUCTION

Oxidative stress-induced trophoblast cell dysfunction is a major pathology in preeclampsia (PE). Recently, CCAAT/enhancer binding protein beta (C/EBPβ) has been investigated as a tumor suppressor that participates in tumor invasion. However, the function of C/EBPβ in trophoblast cells remains unknown. Our study was designed to detect the expression of C/EBPβ in the preeclamptic placenta and to identify the underlying mechanisms of oxidative stress.

METHODS

Human placental tissues with PE were collected. The expression of C/EBPβ and β-catenin were detected. Human first trimester extravillous trophoblast cell (HTR8/SVneo) line exposed to hypoxia/reoxygenation (H/R) was employed as an oxidative stress model in vitro to investigate the effects of C/EBPβ on invasion and the expression of β-catenin. Moreover, first trimester-derived placental villous explants were used to verify the effects of C/EBPβ and β-catenin in placentation.

RESULTS

In preeclamptic placentas, C/EBPβ was overexpressed and β-catenin was decreased. In addition, C/EBPβ was found to have increased expression in H/R-treated HTR8/SVneo cells and villous explants. C/EBPβ knockdown and β-catenin activation could significantly promote the invasion of HTR8/SVneo cells, enhance the outgrowth and migration in villous explants and inhibit the excessive generation of intracellular ROS. These findings might be related to the increased activities of MMP-2/9 and the decreased expression of TIMP-1/2. Meanwhile, C/EBPβ knockdown remarkably increased the expression of β-catenin.

DISCUSSION

We hypothesize that the oxidative stress-induced overexpression of C/EBPβ might influence the activity of MMPs by regulating the Wnt/β-catenin signaling pathway to affect the invasion of trophoblast cells, which then participate in the pathogenesis of preeclampsia.

Human placental trophoblast invasion and differentiation: a particular focus on Wnt signaling

Wingless ligands, a family of secreted proteins, are critically involved in organ development and tissue homeostasis by ensuring balanced rates of stem cell proliferation, cell death and differentiation. Wnt signaling components also play crucial roles in murine placental development controlling trophoblast lineage determination, chorioallantoic fusion and placental branching morphogenesis. However, the role of the pathway in human placentation, trophoblast development and differentiation is only partly understood. Here, we summarize our present knowledge about Wnt signaling in the human placenta and discuss its potential role in physiological and aberrant trophoblast invasion, gestational diseases and choriocarcinoma formation. Differentiation of proliferative first trimester cytotrophoblasts into invasive extravillous trophoblasts is associated with nuclear recruitment of β -catenin and induction of Wnt-dependent T-cell factor 4 suggesting that canonical Wnt signaling could be important for the formation and function of extravillous trophoblasts. Indeed, activation of the pathway was shown to promote trophoblast invasion in different in vitro trophoblast model systems as well as trophoblast cell fusion. Methylation-mediated silencing of inhibitors of Wnt signaling provided evidence for epigenetic activation of the pathway in placental tissues and choriocarcinoma cells. Similarly, abundant nuclear expression of β -catenin in invasive trophoblasts of complete hydatidiform moles suggested a role for hyper-activated Wnt signaling. In contrast, upregulation of Wnt inhibitors was noticed in placentae of women with preeclampsia, a disease characterized by shallow trophoblast invasion and incomplete spiral artery remodeling. Moreover, changes in Wnt signaling have been observed upon cytomegalovirus infection and in recurrent abortions. In summary, the current literature suggests a critical role of Wnt signaling in physiological and abnormal trophoblast function.

The Lipid Transfer Protein StarD7: Structure, Function, and Regulation

The steroidogenic acute regulatory (StAR) protein-related lipid transfer (START) domain proteins constitute a family of evolutionarily conserved and widely expressed proteins that have been implicated in lipid transport, metabolism, and signaling. The 15 well-characterized mammalian START domain-containing proteins are grouped into six subfamilies. The START domain containing 7 mRNA encodes StarD7, a member of the StarD2/phosphatidylcholine transfer protein (PCTP) subfamily, which was first identified as a gene overexpressed in a choriocarcinoma cell line. Recent studies show that the StarD7 protein facilitates the delivery of phosphatidylcholine to the mitochondria. This review summarizes the latest advances in StarD7 research, focusing on the structural and biochemical features, protein-lipid interactions, and mechanisms that regulate StarD7 expression. The implications of the role of StarD7 in cell proliferation, migration, and differentiation are also discussed.

StarD7 knockdown modulates ABCG2 expression, cell migration, proliferation, and differentiation of human choriocarcinoma JEG-3 cells

Background

StAR-related lipid transfer domain containing 7 (StarD7) is a member of the START-domain protein family whose function still remains unclear. Our data from an explorative microarray assay performed with mRNAs from StarD7 siRNA-transfected JEG-3 cells indicated that ABCG2 (ATP-binding cassette sub-family G member 2) was one of the most abundantly downregulated mRNAs.

Methodology/Principal Findings

Here, we have confirmed that knocking down StarD7 mRNA lead to a decrease in the xenobiotic/lipid transporter ABCG2 at both the mRNA and protein levels (−26.4% and −41%, p<0.05, at 48 h of culture, respectively). Also a concomitant reduction in phospholipid synthesis, bromodeoxyuridine (BrdU) uptake and ³H-thymidine incorporation was detected. Wound healing and transwell assays revealed that JEG-3 cell migration was significantly diminished (p<0.05). Conversely, biochemical differentiation markers such as human chorionic gonadotrophin β-subunit (βhCG) protein synthesis and secretion as well as βhCG and syncytin-1 mRNAs were increased approximately 2-fold. In addition, desmoplakin immunostaining suggested that there was a reduction of intercellular desmosomes between adjacent JEG-3 cells after knocking down StarD7.

Conclusions/Significance

Altogether these findings provide evidence for a role of StarD7 in cell physiology indicating that StarD7 modulates ABCG2 multidrug transporter level, cell migration, proliferation, and biochemical and morphological differentiation marker expression in a human trophoblast cell model.

A decrease in DKK1, a WNT inhibitor, contributes to placental lipid accumulation in an obesity-prone rat model

Placenta, as the sole transport mechanism between mother and fetus, links the maternal physical state and the immediate as well as lifelong outcomes of the offspring. The present study examined the consequences of maternal obesity on placental lipid accumulation and metabolism. Pregnant obesity-prone (OP) and obesity-resistant (OR) rat strains were fed a control diet throughout gestation. Placentas were collected on Gestational Day 21 for mRNA and oxidative stress analysis, and frozen placental sections were analyzed for fat accumulation as well as beta-catenin and Dickkopf homolog 1 (Xenopus laevis) (DKK1) localization. JEG3 trophoblast cells were cultured in vitro to determine the relationship between DKK1 and lipid accumulation. Maternal plasma and placental nonesterified fatty acids and triglycerides (TG) were elevated in OP dams. Placental Dkk1 mRNA content was 4-fold lower in OP placentas, and a significant increase was noted in beta-catenin accumulation as well as in mRNA content of fat transport and TG synthesis genes, including Ppard (peroxisome proliferator-activated receptor delta), Slc27a1 (fatty acid transport protein 1; also known as Fatp1), Cd36 (cluster of differentiation 36; also known as fatty acid translocation [Fat]), Lipin1, and Lipin3. Significant lipid accumulation was found within the decidual zones in OP, but not OR, placentas, and thickness of the decidual and junctional zones was significantly smaller in OP than in OR placentas. Overexpression of DKK1 in JEG3 cells decreased lipid accumulation and mRNA content of PPARD, SLC27A1, CD36, LIPIN1, and LIPIN3. Our results demonstrate that DKK1 is regulating certain aspects of placental lipid metabolism through the WNT signaling pathway.

StarD7 gene expression in trophoblast cells: contribution of SF-1 and Wnt-beta-catenin signaling

Steroidogenic acute regulatory protein-related lipid transfer domain containing 7 (StarD7) is a poorly characterized member of the steroidogenic acute regulatory protein-related lipid transfer proteins, up-regulated in JEG-3 cells, involved in intracellular transport and metabolism of lipids. Previous studies dealing with the mechanisms underlying the human StarD7 gene expression led us to define the cis-acting regulatory sequences in the StarD7 promoter using as a model JEG-3 cells. These include a functional T cell-specific transcription factor 4 (TCF4) site involved in Wnt-β-catenin signaling. To understand these mechanisms in more depth, we examined the steroidogenic factor 1 (SF-1) contribution to StarD7 expression. Cotransfection experiments in JEG-3 cells point out that the StarD7 promoter is activated by SF-1, and this effect is increased by forskolin. EMSA using JEG-3 nuclear proteins demonstrated that SF-1 binds to the StarD7 promoter. Additionally, chromatin immunoprecipitation analysis indicated that SF-1 and β-catenin are bound in vivo to the StarD7 promoter. Reporter gene assays in combination with mutations in the SF-1 and TCF4 binding sites revealed that the StarD7 promoter is synergistically activated by SF-1 and β-catenin and that the TCF4 binding site (-614/-608) plays an important role in this activation. SF-1 amino acid mutations involved in the physical interaction with β-catenin abolished this activation; thus demonstrating that the contact between the two proteins is necessary for an efficient StarD7 transcriptional induction. Finally, these data suggest that β-catenin could function as a bridge between SF-1 and TCF4 forming a ternary complex, which would stimulate StarD7 expression. The SF-1 and β-catenin pathway convergence on StarD7 expression may have important implications in the phospholipid uptake and transport, contributing to the normal trophoblast development.

MicroRNA roles in beta-catenin pathway

β-catenin, a key factor in the Wnt signaling pathway, has essential functions in the regulation of cell growth and differentiation. Aberrant β-catenin signaling has been linked to various disease pathologies, including an important role in tumorigenesis. Here, we review the regulation of the Wnt signaling pathway as it relates to β-catenin signaling in tumorigenesis, with particular focus on the role of microRNAs. Finally, we discuss the potential of β-catenin targeted therapeutics for cancer treatment.

Wnt signalling in implantation, decidualisation and placental differentiation--review

The family of secreted Wingless ligands plays major roles in embryonic development, stem cell maintenance, differentiation and tissue homeostasis. Accumulating evidence suggests that the canonical Wnt pathway involving nuclear recruitment of β-catenin and activation of Wnt-dependent transcription factors is also critically involved in development and differentiation of the diverse reproductive tissues. Here, we summarise our present knowledge about expression, regulation and function of Wnt ligands and their frizzled receptors in murine and human endometrial and placental cell types. In mice, Wnt signalling promotes early trophoblast lineage development, blastocyst activation, implantation and chorion-allantois fusion. Moreover, different Wnt ligands play essential roles in the development of the murine uterine tract, in cycling endometrial cells and during decidualisation. In humans, estrogen-dependent endometrial cell proliferation, decidualisation, trophoblast attachment and invasion were shown to be controlled by the particular signalling pathway. Failures in Wnt signalling are associated with infertility, endometriosis, endometrial cancer and gestational diseases such as complete mole placentae and choriocarcinomas. However, our present knowledge is still scarce due to the complexity of the Wnt network involving numerous ligands, receptors and non-canonical pathways. Hence, much remains to be learned about the role of different Wnt signalling cascades in reproductive cell types and their changes under pathological conditions.

Governing the invasive trophoblast: current aspects on intra- and extracellular regulation

This review summarizes several aspects especially of regulating factors governing trophoblast invasion. Those include the composition of the extracellular matrix containing a variety of matrix metalloproeinases and their inhibitors, but also intracellular signals. Furthermore, a newly described trophoblast subtype, the endoglandular trophoblast, is presented. Its presence may provide a possible mechanism for opening and connecting uterine glands into the intervillous space. Amongst others, two intracellular signalling pathways are crucial for regulation of trophoblast functions and development: Wnt- and signal transducer and activator of transcription (STAT)3 signalling. Wnt signalling promotes implantation, placentation and trophoblast differentiation. Several Wnt-dependent cascades and regulatory mechanisms display different functions in trophoblast cells. The STAT3 signalling system is fundamental for induction and regulation of invasiveness in physiological trophoblastic cells, but also in tumours. The role of galectins (Gal) in trophoblast regulation and placenta development comes increasingly into focus. The Gal- 1-4, 7-10 and 12-14 have been detected in humans. Detailed information is only available for Gal-1, -2, -3, -4, -9 and -12 in endometrium and decidua. Gal-1, -3 and -13 (-14) have been detected and studied in trophoblast cells.