Sphingosine-1-phosphate promotes extravillous trophoblast cell invasion by activating MEK/ERK/MMP-2 signaling pathways via S1P/S1PR1 axis activation

Synergistic effects of dendrosomal nanocurcumin and oxaliplatin on oncogenic properties of ovarian cancer cell lines by down-expression of MMPs

BACKGROUND

Contrary to the advantageous anticancer activities of curcumin (Cur), limited bioavailability and solubility hindered its efficacy. Here, nontoxic dendrosomal nano carrier with Cur was used to overcome these problems. Despite considerable antitumor properties of Oxaliplatin (Oxa), the limiting factors are drug resistance and adverse side-effects. The hypothesis of this study was to evaluate the possible synergism between dendrosomal nanocurcumin (DNC) and Oxa and these agents showed growth regulatory effects on SKOV3 and OVCAR3 cells.

METHODS AND MATERIALS

In the present study, colony formation, wound healing motility, cell adhesion, transwell invasion and migration assay and cell cycle arrest with or without DNC, Oxa and Combination were defined. In addition to, real time PCR and Western blot were used to analyze AKT, PI3K, PKC, JNK, P38 and MMPs mRNAs and proteins expressions. Docking of MMP-2-Cur, MMP-2-DNC and MMP-2-Oxa was performed and the results of all three complexes were simulated by molecular dynamics.

RESULTS

Our findings illustrated that DNC had the greatest effect on cell death as compared to the Cur alone. Moreover, the growth inhibitory effects (such as cell death correlated to apoptosis) were more intense if Oxa was added followed by DNC at 4 h interval. However, insignificant effects were observed upon simultaneous addition of these two agents in both cell lines. Besides, a combination of agents synergistically alters the relative expression of MMP-9.

CONCLUSIONS

The docking results showed that His70 and Asp100 may play a key role at the MMP-2 binding site. The matrigel invasion as well as cell viability of ovarian cancer cell lines SKOV3 and OVCAR3 by DNC alone or in combination with Oxa was inhibited significantly. The inhibitory effects of these agents were due to the differential expression levels of MMP 2 and MMP 9 regulated by multiple downstream signaling cascades. From the molecular dynamic simulation studies, it was confirmed that DNC established a strong interaction with MMP-2.

A genome-wide CRISPR-Cas9 knockout screen identifies essential and growth-restricting genes in human trophoblast stem cells

The recent derivation of human trophoblast stem cells (hTSCs) provides a scalable in vitro model system of human placental development, but the molecular regulators of hTSC identity have not been systematically explored thus far. Here, we utilize a genome-wide CRISPR-Cas9 knockout screen to comprehensively identify essential and growth-restricting genes in hTSCs. By cross-referencing our data to those from similar genetic screens performed in other cell types, as well as gene expression data from early human embryos, we define hTSC-specific and -enriched regulators. These include both well-established and previously uncharacterized trophoblast regulators, such as ARID3A, GATA2, and TEAD1 (essential), and GCM1, PTPN14, and TET2 (growth-restricting). Integrated analysis of chromatin accessibility, gene expression, and genome-wide location data reveals that the transcription factor TEAD1 regulates the expression of many trophoblast regulators in hTSCs. In the absence of TEAD1, hTSCs fail to complete faithful differentiation into extravillous trophoblast (EVT) cells and instead show a bias towards syncytiotrophoblast (STB) differentiation, thus indicating that this transcription factor safeguards the bipotent lineage potential of hTSCs. Overall, our study provides a valuable resource for dissecting the molecular regulation of human placental development and diseases.

Impaired Sphingosine-1-Phosphate Synthesis Induces Preeclampsia by Deactivating Trophoblastic YAP (Yes-Associated Protein) Through S1PR2 (Sphingosine-1-Phosphate Receptor-2)-Induced Actin Polymerizations

Incomplete spiral artery remodeling, caused by impaired extravillous trophoblast invasion, is a fundamental pathogenic process associated with malplacentation and the development of preeclampsia. Nevertheless, the mechanisms controlling this regulation of trophoblast invasion are largely unknown. We report that sphingosine-1-phosphate synthesis and expression is abundant in healthy trophoblast, whereas in pregnancies complicated by preeclampsia the placentae are associated with reduced sphingosine-1-phosphate and lower SPHK1 (sphingosine kinase 1) expression and activity. In vivo inhibition of sphingosine kinase 1 activity during placentation in pregnant mice led to decreased placental sphingosine-1-phosphate production and defective placentation, resulting in a preeclampsia phenotype. Moreover, sphingosine-1-phosphate increased HTR8/SVneo (immortalized trophoblast cells) cell invasion in a Hippo-signaling-dependent transcriptional coactivator YAP (Yes-associated protein) dependent manner, which is activated by S1PR2 (sphingosine-1-phosphate receptor-2) and downstream RhoA/ROCK induced actin polymerization. Mutation-based YAP-5SA demonstrated that sphingosine-1-phosphate activation of YAP could be either dependent or independent of Hippo signaling. Together, these findings suggest a novel pathogenic pathway of preeclampsia via disrupted sphingosine-1-phosphate metabolism and signaling-induced, interrupted actin dynamics and YAP deactivation; this may lead to potential novel intervention targets for the prevention and management of preeclampsia.

Sphingolipids in HDL - Potential markers for adaptation to pregnancy?

Plasma high density lipoprotein (HDL) exhibits many functions that render it an effective endothelial protective agent and may underlie its potential role in protecting the maternal vascular endothelium during pregnancy. In non-pregnant individuals, the HDL lipidome is altered in metabolic disease compared to healthy individuals and is linked to reduced cholesterol efflux, an effect that can be reversed by lifestyle management. Specific sphingolipids such as sphingosine-1-phosphate (S1P) have been shown to mediate the vaso-dilatory effects of plasma HDL via interaction with the endothelial nitric oxide synthase pathway. This review describes the relationship between plasma HDL and vascular function during healthy pregnancy and details how this is lost in pre-eclampsia, a disorder of pregnancy associated with widespread endothelial dysfunction. Evidence of a role for HDL sphingolipids, in particular S1P and ceramide, in cardiovascular disease and in healthy pregnancy and pre-eclampsia is discussed. Available data suggest that HDL-S1P and HDL-ceramide can mediate vascular protection in healthy pregnancy but not in preeclampsia. HDL sphingolipids thus are of potential importance in the healthy maternal adaptation to pregnancy.

Sphingosine kinases negatively regulate the expression of matrix metalloproteases (MMP1 and MMP3) and their inhibitor TIMP3 genes via sphingosine 1-phosphate in extravillous trophoblasts

PURPOSE

Extracellular matrix remodeling is essential for extravillous trophoblast (EVT) cell migration and invasion during placental development and regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteases (TIMPs). Sphingosine kinases (SPHK1 and SPHK2) synthesize sphingosine-1-phosphate (S1P), which works either intracellularly or extracellularly via its receptors S1PR1-5 in an autocrine or paracrine manner. The role of SPHKs/S1P in regulating the expression of MMPs and TIMPs in EVT is mostly unknown and forms the primary objective of the study.

METHODS

HTR-8/SVneo cells were used as a model of EVT. To inhibit the expression of SPHKs, cells were treated with specific inhibitors, SK1-I and SKI-II, or gene-specific siRNAs. The expressions of MMPs and TIMPs were estimated by qPCR.

RESULTS

We demonstrated that SPHK1, MMP1-3, and TIMP1-3 were highly expressed in HTR-8/SVneo cells. We found that treatment of cells with SK1-I, SKI-II, and knockdown of SPHK1 or SPHK2 increased the expression of MMP1, MMP3, and TIMP3. The addition of extracellular S1P inhibits the upregulation of MMPs and TIMPs in treated cells.

CONCLUSIONS

SPHKs negatively regulate the expression of MMP1, MMP3, and TIMP3. The level of intracellular S1P acts as a negative feedback switch for MMP1, MMP3, and TIMP3 expression in EVT cells.

Physiological and pathological functions of sphingolipids in pregnancy

Signaling by the bioactive sphingolipid, sphingosine 1-phosphate (S1P), and its precursors are emerging areas in pregnancy research. S1P and ceramide levels increase towards end of gestation, suggesting a physiological role in parturition. However, high levels of circulating S1P and ceramide are correlated with pregnancy disorders such as preeclampsia, gestational diabetes mellitus and intrauterine growth restriction. Expression of placental and decidual enzymes that metabolize S1P and S1P receptors are also dysregulated during pregnancy complications. In this review, we provide an in-depth examination of the signaling mechanism of S1P and ceramide in various reproductive tissues during gestation. These factors determine implantation and early pregnancy success by modulating corpus luteum function from progesterone production to luteolysis through to apoptosis. We also highlight the role of S1P through receptor signaling in inducing decidualization and angiogenesis in the decidua, as well as regulating extravillous trophoblast migration to anchor the placenta into the uterine wall. Recent advances on the role of the S1P:ceramide rheostat in controlling the fate of villous trophoblasts and the role of S1P as a negative regulator of trophoblast syncytialization to a multinucleated placental barrier are discussed. This review also explores the role of S1P in anti-inflammatory and pro-inflammatory signaling, its role as a vasoconstrictor, and the effects of S1P metabolizing enzymes and receptors in pregnancy.

Hypoxia-induced GPR4 suppresses trophoblast cell migration and proliferation through the MAPK signaling pathway

Pre-eclampsia (PE), a common pregnancy-systemic syndrome, is characterized by proteinuria and hypertension and is the leading cause of maternal and fetal mortality. Thus, we aim to investigate the role of G-Protein Coupled Receptor 4 (GPR4) in PE and the underlying molecular mechanism. In this study, GSE66273 microarray data were obtained from the Gene Expression Omnibus(GEO) database of the National Center for Biotechnology Information, and Gene set enrichment analysis (GSEA) was performed by GSEA software. qRT-PCR and Immunohistochemistry (IHC) or western blotting were used to assay for the expression of GPR4 in PE placentas and HTR8/SVneo cells. The influence of acidosis and hypoxia environments on the expression of GPR4 was explored using western blotting. Cell proliferation and migration of HTR8/SVneo cells were measured using EdU and MTT assays and migration assay, respectively. Moreover, expressions of MEK1/2, p-MEK1/2, ERK1/2, and p-ERK1/2 in HTR8/SVneo cells were assayed by western blotting. Our data demonstrated that the expression of GPR4 was up regulated in PE placentas. Increase in acidic pH and hypoxic levels increased the expression of GPR4 in HTR8/SVneo cells. GPR4 inhibited cell proliferation and migration in the HTR8/SVneo cells. GPR4 silencing enhanced the phosphorylation of p-MEK1/2and p-ERK1/2 in HTR8/SVneo cells. Additionally, we found that pathway inhibitor partially reversed the effects of GPR4 on proliferation and migration of HTR8/SVneo cells. In conclusions, these results show that GPR4 suppressed cell proliferation and migration by inhibiting MAPK signaling pathway in PE.

Maternal and fetal alkaline ceramidase 2 is required for placental vascular integrity in mice

Sphingolipids have been implicated in mammalian placental development and function, but their regulation in the placenta remains unclear. Herein we report that alkaline ceramidase 2 (ACER2) plays a key role in sustaining the integrity of the placental vasculature by regulating the homeostasis of sphingolipids in mice. The mouse alkaline ceramidase 2 gene (Acer2) is highly expressed in the placenta between embryonic day (E) 9.5 and E12.5. Acer2 deficiency in both the mother and fetus decreases the placental levels of sphingolipids, including sphingoid bases (sphingosine and dihydrosphingosine) and sphingoid base-1-phosphates (sphingosine-1-phosphate and dihydrosphingosine-1-phosphate) and results in the in utero death of ≈50% of embryos at E12.5 whereas Acer2 deficiency in either the mother or fetus has no such effects. Acer2 deficiency causes hemorrhages from the maternal vasculature in the junctional and/or labyrinthine zones in E12.5 placentas. Moreover, hemorrhagic but not non-hemorrhagic Acer2-deficient placentas exhibit an expansion of parietal trophoblast giant cells with a concomitant decrease in the area of the fetal blood vessel network in the labyrinthine zone, suggesting that Acer2 deficiency results in embryonic lethality due to the atrophy of the fetal blood vessel network in the placenta. Taken together, these results suggest that ACER2 sustains the integrity of the placental vasculature by controlling the homeostasis of sphingolipids in mice.

miR‑181b‑5p inhibits trophoblast cell migration and invasion through targeting S1PR1 in multiple abnormal trophoblast invasion‑related events

Normal placentation and successful maintenance of pregnancy depend on the successful migration and invasion of trophoblasts into maternal tissues. Previous studies reported that microRNAs (miRs) are expressed in trophoblasts, and can regulate their migration and invasion. The present study aimed to investigate miR‑181b‑5p function in HTR‑8/SVneo trophoblasts and explore its underlying mechanism in the pathogenesis of multiple abnormal trophoblast invasion‑related events. Reverse‑transcription quantitative PCR and western blotting were used to test the expression of miR‑181b‑5p and sphingosine‑1‑phosphate receptor 1 (S1PR1) in samples of multiple abnormal trophoblast invasion‑related events. Transwell invasion and wound healing assays were performed to determine cell invasion and migration abilities. A luciferase reporter assay was conducted to identify the downstream target of miR‑181b‑5p. Overexpression of miR‑181b‑5p suppressed HTR‑8/SVneo cell migration and invasion, whereas inhibition of miR‑181b‑5p induced an opposite effect. The S1PR1 gene was further identified as a novel direct target of miR‑181b‑5p. Specifically, miR‑181b‑5p bound directly to the 3'‑untranslated region of S1PR1 and suppressed its expression. Moreover, overexpression of S1PR1 reversed the inhibitory effect of miR‑181b‑5p. Taken together, ectopic expression of miR‑181b‑5p impaired the migration and invasion of trophoblasts by directly targeting S1PR1, thereby providing new insights into the pathogenesis of multiple abnormal trophoblast invasion‑related events.

MicroRNAs in Uteroplacental Vascular Dysfunction

Pregnancy complications of preeclampsia and intrauterine growth restriction (IUGR) are major causes of maternal and perinatal/neonatal morbidity and mortality. Although their etiologies remain elusive, it is generally accepted that they are secondary to placental insufficiency conferred by both failure in spiral artery remodeling and uteroplacental vascular malfunction. MicroRNAs (miRNAs) are small no-coding RNA molecules that regulate gene expression at the post-transcriptional level. Increasing evidence suggests that miRNAs participate in virtually all biological processes and are involved in numerous human diseases. Differentially expressed miRNAs in the placenta are typical features of both preeclampsia and IUGR. Dysregulated miRNAs target genes of various signaling pathways in uteroplacental tissues, contributing to the development of both complications. In this review, we provide an overview of how aberrant miRNA expression in preeclampsia and IUGR impacts the expression of genes involved in trophoblast invasion and uteroplacental vascular adaptation.

Activation of the Sphingosine 1 Phosphate-Rho Pathway in Pterygium and in Ultraviolet-Irradiated Normal Conjunctiva

Sphingosine 1 phosphate (S1P) is a bioactive lipid that regulates cellular activity, including proliferation, cytoskeletal organization, migration, and fibrosis. In this study, the potential relevance of S1P–Rho signaling in pterygium formation and the effects of ultraviolet (UV) irradiation on activation of the S1P/S1P receptor axis and fibrotic responses were investigated in vitro. Expressions of the S1P2, S1P4, and S1P5 receptors were significantly higher in pterygium tissue than in normal conjunctiva, and the concentration of S1P was significantly elevated in the lysate of normal conjunctival fibroblast cell (NCFC) irradiated with UV (UV-NCFCs). RhoA activity was significantly upregulated in pterygium fibroblast cells (PFCs) and UV-NCFCs, and myosin phosphatase–Rho interacting protein (MRIP) was upregulated, and myosin phosphatase target subunit 1 (MYPT1) was downregulated in PFCs. Fibrogenic changes were significantly upregulated in both PFCs and UV-NCFCs compared to NCFCs. We found that the activation of the S1P receptor–Rho cascade was observed in pterygium tissue. Additionally, in vitro examination showed S1P–rho activation and fibrogenic changes in PFCs and UV-NCFCs. S1P elevation and the resulting upregulation of the downstream Rho signaling pathway may be important in pterygium formation; this pathway offers a potential therapeutic target for suppressing pterygium generation.

Sphingolipid/Ceramide Pathways and Autophagy in the Onset and Progression of Melanoma: Novel Therapeutic Targets and Opportunities

Melanoma is a malignant tumor deriving from neoplastic transformation of melanocytes. The incidence of melanoma has increased dramatically over the last 50 years. It accounts for most cases of skin cancer deaths. Early diagnosis leads to remission in 90% of cases of melanoma; conversely, for melanoma at more advanced stages, prognosis becomes more unfavorable also because dvanced melanoma is often resistant to pharmacological and radiological therapies due to genetic plasticity, presence of cancer stem cells that regenerate the tumor, and efficient elimination of drugs. This review illustrates the role of autophagy in tumor progression and resistance to therapy, focusing on molecular targets for future drugs.

S100P enhances the motility and invasion of human trophoblast cell lines

S100P has been shown to be a marker for carcinogenesis where its expression in solid tumours correlates with metastasis and a poor patient prognosis. This protein's role in any physiological process is, however, unknown. Here we first show that S100P is expressed both in trophoblasts in vivo as well as in some corresponding cell lines in culture. We demonstrate that S100P is predominantly expressed during the early stage of placental formation with its highest expression levels occurring during the first trimester of gestation, particularly in the invading columns and anchoring villi. Using gain or loss of function studies through overexpression or knockdown of S100P expression respectively, our work shows that S100P stimulates both cell motility and cellular invasion in different trophoblastic and first trimester EVT cell lines. Interestingly, cell invasion was seen to be more dramatically affected than cell migration. Our results suggest that S100P may be acting as an important regulator of trophoblast invasion during placentation. This finding sheds new light on a hitherto uncharacterized molecular mechanism which may, in turn, lead to the identification of novel targets that may explain why significant numbers of confirmed human pregnancies suffer complications through poor placental implantation.

Vitamin D attenuates sphingosine-1-phosphate (S1P)-mediated inhibition of extravillous trophoblast migration

INTRODUCTION

Failure of trophoblast invasion and remodelling of maternal blood vessels leads to the pregnancy complication pre-eclampsia (PE). In other systems, the sphingolipid, sphingosine-1-phosphate (S1P), controls cell migration therefore this study determined its effect on extravillous trophoblast (EVT) function.

METHODS

A transwell migration system was used to assess the behaviour of three trophoblast cell lines, Swan-71, SGHPL-4, and JEG3, and primary human trophoblasts in the presence or absence of S1P, S1P pathway inhibitors and 1,25(OH)₂D₃. QPCR and immunolocalisation were used to demonstrate EVT S1P receptor expression.

RESULTS

EVTs express S1P receptors 1, 2 and 3. S1P inhibited EVT migration. This effect was abolished in the presence of the specific S1PR2 inhibitor, JTE-013 (p < 0.05 versus S1P alone) whereas treatment with the S1R1/3 inhibitor, FTY720, had no effect. In other cell types S1PR2 is regulated by vitamin D; here we found that treatment with 1,25(OH)₂D₃ for 48 or 72 h reduces S1PR2 (4-fold; <0.05), but not R1 and R3, expression. Moreover, S1P did not inhibit the migration of cells exposed to 1,25(OH)₂D₃ (p < 0.05).

DISCUSSION

This study demonstrates that although EVT express three S1P receptor isoforms, S1P predominantly signals through S1PR2/Gα_12/13 to activate Rho and thereby acts as potent inhibitor of EVT migration. Importantly, expression of S1PR2, and therefore S1P function, can be down-regulated by vitamin D. Our data suggest that vitamin D deficiency, which is known to be associated with PE, may contribute to the impaired trophoblast migration that underlies this condition.

Mutant p53 stimulates cell invasion through an interaction with Rad21 in human ovarian cancer cells

Missense mutations of TP53 are extremely common, and mutant p53 accumulation and gain-of-function play crucial roles in human ovarian cancer. Here, we investigated the role of mutant p53 in cell migration and invasion as well as its underlying molecular mechanisms in human ovarian cancer cells. Overexpression of mutant p53 significantly increased migration and invasion in p53-null SKOV3 cells. In contrast, knockdown of mutant p53 significantly compromised mutant p53-induced cell migration and invasion. Microarray analysis revealed that several migration/invasion-related genes, including S1PR1 (Sphingosine-1-phosphate receptor 1) and THBS1 (Thrombospodin 1), were significantly upregulated in SKOV3 cells that overexpressed mutant p53-R248 (SKOV3^R248). We found that Rad21 is involved in the transcriptional regulation of the migration/invasion-related genes induced by mutant p53-R248. Knockdown of Rad21 significantly attenuated the mutant p53-R248-induced invasion and the expressions of S1PR1 and THBS1. Moreover, co-immunoprecipitation and chromatin immunoprecipitation assays revealed that mutant p53 interacts with Rad21 and binds to the Rad21-binding elements in the S1PR1 and THBS1 genes. Finally, downregulation of S1PR1 significantly attenuated the invasion driven by mutant p53-R248. These novel findings reveal that mutant p53-R248 maintains gain-of-function activity to stimulate cell invasion and induces the related gene expressions through an interaction with Rad21 in human ovarian cancer cells.

miR-125b Enhances IL-8 Production in Early-Onset Severe Preeclampsia by Targeting Sphingosine-1-Phosphate Lyase 1

Preeclampsia (PE) is one of the leading causes of maternal and perinatal mortality and morbidity. One of the main hallmarks observed in PE is impaired inflammation state. In the current study, we found that miR-125b was deregulated in placental tissues and plasma derived from PE patients, which suggest a potential association between this miRNA and the pathogenesis of PE. Overexpression of miR-125b significantly reduced SGPL1 expression, and luciferase assays confirmed that SGPL1 is a direct target of miR-125b. We also found that miR-125b enhanced IL-8 production by directly targeting sphingosine-1-phosphate lyase 1 (SGPL1), and this effect could be reversed by SGPL1 overexpression. In placentas derived from PE patients, a negative correlation of miR-125b and SGPL1 was observed, and IL-8 was validated to be increased in the circulation of PE patients. Our data demonstrated a critical role of miR-125b in IL-8 production and the development of PE.

Gene silencing of USP1 by lentivirus effectively inhibits proliferation and invasion of human osteosarcoma cells

Osteosarcoma is the most frequent malignant bone tumor, affecting the extremities of adolescents and young adults. Ubiquitin-specific protease 1 (USP1) plays a critical role in many cellular processes including proteasome degradation, chromatin remodeling and cell cycle regulation. In the present study, we discovered that USP1 was overexpressed in 26 out of 30 osteosarcoma tissues compared to cartilage tumor tissues and normal bone tissues. We then constructed a lentiviral vector mediating RNA interference (RNAi) targeting USP1 and demonstrated that it significantly suppressed the mRNA and protein expression of the USP1 gene in U2OS cells. Knockdown of USP1 inhibited the growth and colony-forming, as well as significantly reduced the invasiveness of U2OS cells. Western blot analysis indicated that suppression of USP1 downregulated the expression of many proteins including SIK2, MMP-2, GSK-3β, Bcl-2, Stat3, cyclin E1, Notch1, Wnt-1 and cyclin A1. Most of these proteins are associated with tumor genesis and development. RNAi of SIK2 significantly decreased SIK2 protein expression and inhibited the ability of forming colonies, as well as induced apoptosis and reduced the invasiveness of U2OS cells. Collectively, our results suggest that silencing USP1 inhibits cell proliferation and invasion in U2OS cells. Therefore, USP1 may provide a novel therapeutic target for the treatment of osteosarcoma.

Impairment of Angiogenic Sphingosine Kinase-1/Sphingosine-1-Phosphate Receptors Pathway in Preeclampsia

Preeclampsia (PE), is a serious pregnancy disorder characterized in the early gestation by shallow trophoblast invasion, impaired placental neo-angiogenesis, placental hypoxia and ischemia, which leads to maternal and fetal morbidity and mortality. Here we hypothesized that angiogenic sphingosine kinase-1 (SPHK1)/sphingosine-1-phosphate (S1P) receptors pathway is impaired in PE. We found that SPHK1 mRNA and protein expression are down-regulated in term placentae and term chorionic villous explants from patients with PE or severe PE (PES), compared with controls. Moreover, mRNA expression of angiogenic S1PR1 and S1PR3 receptors were decreased in placental samples of PE and PES patients, whereas anti-angiogenic S1PR2 was up-regulated in chorionic villous tissue of PES subjects, pointing to its potential atherogenic and inflammatory properties. Furthermore, in in vitro (JAR cells) and ex vivo (chorionic villous explants) models of placental hypoxia, SPHK1 mRNA and protein were strongly up-regulated under low oxygen tension (1% 0₂). In contrast, there was no change in SPHK1 expression under the conditions of placental physiological hypoxia (8% 0₂). In both models, nuclear protein levels of HIF1A were increased at 1% 0₂ during the time course, but there was no up-regulation at 8% 0₂, suggesting that SPHK1 and HIF1A might be the part of the same canonical pathway during hypoxia and that both contribute to placental neovascularization during early gestation. Taken together, this study suggest the SPHK1 pathway may play a role in the human early placentation process and may be involved in the pathogenesis of PE.

Improved Proliferation and Differentiation of Bone Marrow Mesenchymal Stem Cells Into Vascular Endothelial Cells With Sphingosine 1-Phosphate

The practical use of bone marrow mesenchymal stem cells (MSCs), considered to be the best candidate in the field of regenerative medicine, is limited by the low efficiency of MSC differentiation. Sphingosine 1-phosphate (S1P) could promote proliferation, survival, and differentiation of many types of cells, but its effects on MSCs remain elusive. In this study, S1P was added during primary MSCs (PR-MSCs) culture and the effects of S1P on proliferation, survival, and differentiation of PR-MSCs were evaluated. The results showed that S1P could improve PR-MSCs proliferation activity in a concentration-dependent manner, and the apoptosis of PR-MSCs cultured in hypoxia was significantly reduced in the S1P-treated group compared to the control group. After being cultured with vascular endothelial growth factor for 7 days, the specific genes of endothelial cells were highly expressed in S1P-treated PR-MSCs compared to control group, which coincided with the augumented production of hepatocyte growth factor, stromal cell-derived factor-1, and insulin-like growth factor-1. In summary, our results suggest that S1P can promote proliferation, survival, and differentiation into vascular endothelial cells of PR-MSCs. These results will promote the clinical application of PR-MSCs and deepen our understanding of the function mechanism of S1P.

Arsenic sulfide inhibits cell migration and invasion of gastric cancer in vitro and in vivo

BACKGROUND

We previously showed that arsenic sulfide (As4S4) induced cell cycle arrest and apoptosis in several human solid tumor cell lines, including those of gastric cancer. In this study, we investigated the effect of As4S4 on the migration and invasion of gastric cancer cells both in vitro and in vivo.

METHODS

The human gastric cancer cell lines AGS and MGC803 were selected as in vitro models. Wound-healing migration assay and Transwell invasion assay were carried out to determine the effects of As4S4 on cell migration and invasion. The expressions of E-cadherin, β-catenin, Sp1, KLF4, and VEGF were measured by Western blotting analysis. The activities of matrix metalloproteinase (MMP)-2 and MMP-9 in MGC803 cells were demonstrated by zymography assay. A mouse xenograft model was established by inoculation with MGC803 cells, then intraperitoneal injected with As4S4 for 3 weeks and monitored for body weight and tumor changes. Finally, the inhibition rate of tumor growth was calculated, and the expression of proteins and genes associated with tumor invasion and metastasis in tumor tissues were measured by immunohistochemistry, Western blotting, and real-time polymerase chain reaction assay.

RESULTS

As4S4 significantly inhibited the migration and invasion of gastric cancer cell lines. The expression of E-cadherin and KLF4 was upregulated, while the expressions of β-catenin, VEGF, and Sp1 were downregulated following treatment with As4S4. Moreover, the protease activities of MMP-2 and MMP-9 were suppressed by As4S4 in MGC803 cells. Meanwhile, As4S4 effectively suppressed the abilities of tumor growth and invasion in the xenograft tumor model. We found that As4S4 upregulated the expression of E-cadherin and downregulated the expression of β-catenin, Sp1, VEGF, and CD34 in mouse tumor tissues, consistent with the results in vitro.

CONCLUSION

As4S4 inhibited the migration and invasion of gastric cancer cells by blocking tumor cell adhesion, decreasing the ability of tumor cells to destroy the basement membrane, and therefore suppressing their angiogenesis.

Sphingosine 1-phosphate regulates IL-8 expression and secretion via S1PR1 and S1PR2 receptors-mediated signaling in extravillous trophoblast derived HTR-8/SVneo cells

INTRODUCTION

Both villous and extravillous trophoblast (EVT) cells produce a wide range of cytokines and also respond to them in autocrine and paracrine manner. Deregulation of cytokine secretion may lead to various pathologic conditions including preeclampsia. IL-8, a pro-inflammatory cytokine, regulates various cellular functions such as neutrophil trafficking, cell adhesion, tumor growth and has a role in placental development. IL-8 also promotes trophoblast cell migration and invasion, and stimulates the secretion of progesterone. The induction and mechanism of IL-8 secretion by EVT is still unknown.

METHODS

IL-8 mRNA expression and secretion was determined using real-time PCR and ELISA respectively. To identify the mechanism of IL-8 expression and secretion, selective antagonists and agonist of S1P receptor subtypes, Rac1 and Rho-kinase inhibitors were used.

RESULTS

We found that S1P induces IL-8 gene expression and protein secretion in EVT derived HTR-8/SVneo cells but not in BeWo cells. SEW2781, the selective agonist of S1PR(1), induced IL-8 gene expression but not protein secretion. The specific S1PR(2) inhibitor JTE-013 could drastically inhibit IL-8 secretion. Furthermore, pre-treatment of cells with the selective S1PR(1)/S1PR(3) antagonist VPC23019 inhibited IL-8 secretion by ∼45%. Selective Rho-kinase inhibitor Y27632 and Rac1 inhibitor NSC23766 could block IL-8 secretion in these cells.

DISCUSSION

In this study, we could show for the first time that S1P induces IL-8 mRNA expression and protein secretion in EVT cell line. S1P-induced IL-8 gene expression is mainly regulated via S1PR(1) and its secretion is regulated through S1PR(2) receptor subtype. Rho GTPases signaling is essential for S1P-induced IL-8 secretion.

Activation of sonic hedgehog signaling enhances cell migration and invasion by induction of matrix metalloproteinase-2 and -9 via the phosphoinositide-3 kinase/AKT signaling pathway in glioblastoma

Aberrant hedgehog signaling contributes to the development of various malignancies, including glioblastoma (GBM). However, the potential mechanism of hedgehog signaling in GBM migration and invasion has remained to be elucidated. The present study showed that enhanced hedgehog signaling by recombinant human sonic hedgehog N-terminal peptide (rhSHH) promoted the adhesion, invasion and migration of GBM cells, accompanied by increases in mRNA and protein levels of matrix metalloproteinase-2 (MMP-2) and MMP-9. However, inhibition of hedgehog signaling with cyclopamine suppressed the adhesion, invasion and migration of GBM cells, accompanied by decreases in mRNA and protein levels of MMP-2 and -9. Furthermore, it was found that MMP-2- and MMP-9-neutralizing antibodies or GAM6001 reversed the inductive effects of rhSHH on cell migration and invasion. In addition, enhanced hedgehog signaling by rhSHH increased AKT phosphorylation, whereas blockade of hedgehog signaling decreased AKT phosphorylations. Further experiments showed that LY294002, an inhibitor of phosphoinositide-3 kinase (PI3K), decreased rhSHH-induced upregulation of MMP-2 and -9. Finally, the protein expression of glioblastoma-associated oncogene 1 was positively correlated with levels of phosphorylated AKT as well as protein expressions of MMP-2 and -9 in GBM tissue samples. In conclusion, the present study indicated that the hedgehog pathway regulates GBM-cell migration and invasion by increasing MMP-2 and MMP-9 production via the PI3K/AKT pathway.

miR-125b-1-3p inhibits trophoblast cell invasion by targeting sphingosine-1-phosphate receptor 1 in preeclampsia

Preeclampsia (PE) is the leading cause of maternal and perinatal mortality and morbidity. Understanding the molecular mechanisms underlying placentation facilitates the development of better intervention of this disease. MicroRNAs are strongly implicated in the pathogenesis of this syndrome. In current study, we found that miR-125b-1-3p was elevated in placentas derived from preeclampsia patients. Transfection of miR-125b-1-3p mimics significantly inhibited the invasiveness of human trophoblast cells, whereas miR-125b-1-3p inhibitor enhanced trophoblast cell invasion. Luciferase assays identified that S1PR1 was a novel direct target of miR-125b-1-3p in the placenta. Overexpression of S1PR1 could reverse the inhibitory effect of miR-125b-1-3p on the invasion of trophoblast cells. These findings suggested that abnormal expression of miR-125b-1-3p might contribute to the pathogenesis of preeclampsia.