Expression and roles of Slit/Robo in human ovarian cancer

Archetypal clustering reveals physiological mechanisms linking milk yield and fertility in dairy cattle

Fertility in dairy cattle has declined as an unintended consequence of single-trait selection for high milk yield. The unfavorable genetic correlation between milk yield and fertility is now well documented; however, the underlying physiological mechanisms are still uncertain. To understand the relationship between these traits, we developed a method that clusters variants with similar patterns of effects and, after the integration of gene expression data, identifies the genes through which they are likely to act. Biological processes that are enriched in the genes of each cluster were then identified. We identified several clusters with unique patterns of effects. One of the clusters included variants associated with increased milk yield and decreased fertility, where the "archetypal" variant (i.e., the one with the largest effect) was associated with the GC gene, whereas others were associated with TRIM32, LRRK2, and U6-associated snRNA. These genes have been linked to transcription and alternative splicing, suggesting that these processes are likely contributors to the unfavorable relationship between the 2 traits. Another cluster, with archetypal variant near DGAT1 and including variants associated with CDH2, BTRC, SFRP2, ZFHX3, and SLITRK5, appeared to affect milk yield but have little effect on fertility. These genes have been linked to insulin, adipose tissue, and energy metabolism. A third cluster with archetypal variant near ZNF613 and including variants associated with ROBO1, EFNA5, PALLD, GPC6, and PTPRT were associated with fertility but not milk yield. These genes have been linked to GnRH neuronal migration, embryonic development, or ovarian function. The use of archetypal clustering to group variants with similar patterns of effects may assist in identifying the biological processes underlying correlated traits. The method is hypothesis generating and requires experimental confirmation. However, we have uncovered several novel mechanisms potentially affecting milk production and fertility such as GnRH neuronal migration. We anticipate our method to be a starting point for experimental research into novel pathways, which have been previously unexplored within the context of dairy production.

DNA Methylation Signature of Synchronous Endometrioid Endometrial and Ovarian Carcinomas

Next-generation sequencing (NGS) studies have demonstrated that co-occurring sporadic endometrioid endometrial carcinoma (EEC) and endometrioid ovarian carcinoma (EOC) are clonally related, suggesting that they originate from a single primary tumor. Despite clonality, synchronous EEC and EOC when diagnosed at early stage behave indolently, similar to isolated primary EEC or isolated primary EOC. In the present study, we compared the DNA methylation signatures of co-occurring EEC and EOC with those of isolated primary EEC and isolated primary EOC. We also performed targeted NGS to assess the clonal relatedness of 7 co-occurring EEC and EOC (4 synchronous EEC and EOC and 3 metastatic EEC based on pathologic criteria). NGS confirmed a clonal relationship in all co-occurring EEC and EOC. DNA methylation profiling showed distinct epigenetic signatures of isolated primary EEC and isolated primary EOC. Endometrial tumors from co-occurring EEC and EOC clustered with isolated primary EEC while their ovarian counterparts clustered with isolated primary EOC. Three co-occurring EEC and EOC cases with peritoneal lesions showed a closer epigenetic signature and copy number variation profile between the peritoneal lesion and EOC than EEC. In conclusion, synchronous sporadic EEC and EOC are clonally related but demonstrate a shift in DNA methylation signatures between ovarian and endometrial tumors as well as epigenetic overlap between ovarian and peritoneal tumors. Our results suggest that tumor microenvironment in the ovary may play a role in epigenetic modulation of metastatic EEC.

Expanding the phenome and variome of the ROBO-SLIT pathway in congenital heart defects: toward improving the genetic testing yield of CHD

BACKGROUND

Recent studies have shown the implication of the ROBO-SLIT pathway in heart development. Within this study, we aimed to further assess the implication of the ROBO and SLIT genes mainly in bicuspid aortic valve (BAV) and other human congenital heart defects (CHD).

METHODS

We have analyzed a cohort of singleton exome sequencing data comprising 40 adult BAV patients, 20 pediatric BAV patients generated by the Pediatric Cardiac Genomics Consortium, 10 pediatric cases with tetralogy of Fallot (ToF), and one case with coarctation of the aorta. A gene-centered analysis of data was performed. To further advance the interpretation of the variants, we intended to combine more than 5 prediction tools comprising the assessment of protein structure and stability.

RESULTS

A total of 24 variants were identified. Only 4 adult BAV patients (10%) had missense variants in the ROBO and SLIT genes. In contrast, 19 pediatric cases carried variants in ROBO or SLIT genes (61%). Three BAV patients with a severe phenotype were digenic. Segregation analysis was possible for two BAV patients. For the homozygous ROBO4: p.(Arg776Cys) variant, family segregation was consistent with an autosomal recessive pattern of inheritance. The ROBO4: c.3001 + 3G > A variant segregates with the affected family members. Interestingly, these variants were also found in two unrelated patients with ToF highlighting that the same variant in the ROBO4 gene may underlie different cardiac phenotypes affecting the outflow tract development.

CONCLUSION

Our results further reinforce the implication of the ROBO4 gene not only in BAV but also in ToF hence the importance of its inclusion in clinical genetic testing. The remaining ROBO and SLIT genes may be screened in patients with negative or inconclusive genetic tests.

A tumor microenvironment-related risk model for predicting the prognosis and tumor immunity of breast cancer patients

Background

This study aimed to construct a tumor microenvironment (TME)-related risk model to predict the overall survival (OS) of patients with breast cancer.

Methods

Gene expression data from The Cancer Genome Atlas was used as the training set. Differentially expressed gene analysis, prognosis analysis, weighted gene co-expression network analysis, Least Absolute Shrinkage and Selection Operator regression analysis, and Wald stepwise Cox regression were performed to screen for the TME-related risk model. Three Gene Expression Omnibus databases were used to validate the predictive efficiency of the prognostic model. The TME-risk-related biological function was investigated using the gene set enrichment analysis (GSEA) method. Tumor immune and mutation signatures were analyzed between low- and high-TME-risk groups. The patients’ response to chemotherapy and immunotherapy were evaluated by the tumor immune dysfunction and exclusion (TIDE) score and immunophenscore (IPS).

Results

Five TME-related genes were screened for constructing a prognostic signature. Higher TME risk scores were significantly associated with worse clinical outcomes in the training set and the validation set. Correlation and stratification analyses also confirmed the predictive efficiency of the TME risk model in different subtypes and stages of breast cancer. Furthermore, immune checkpoint expression and immune cell infiltration were found to be upregulated in the low-TME-risk group. Biological processes related to immune response functions were proved to be enriched in the low-TME-risk group through GSEA analysis. Tumor mutation analysis and TIDE and IPS analyses showed that the high-TME-risk group had more tumor mutation burden and responded better to immunotherapy.

Conclusion

The novel and robust TME-related risk model had a strong implication for breast cancer patients in OS, immune response, and therapeutic efficiency.

Binding and Efficacy of Anti-Robo4 CAR-T Cells against Solid Tumors

Chimeric antigen receptor expression T (CAR-T) cell therapy has been shown be efficacious against relapsed/refractory B-cell malignant lymphoma and has attracted attention as an innovative cancer treatment. However, cells of solid tumors are less accessible to CAR-T cells; moreover, CAR-T function is decreased in the immunosuppressive state of the tumor microenvironment. Since most tumors induce angiogenesis, we constructed CAR-T cells targeting roundabout homolog 4 (Robo4), which is expressed at high levels in tumor vascular endothelial cells, by incorporating three anti-Robo4 single-chain variable fragments (scFv) that were identified using phage display. We found that binding affinities of the three CARs to mouse and human Robo4 reflected their scFv affinities. More importantly, when each CAR-T cell was assayed in vitro, antigen-specific cytotoxicity, cytokine-producing ability, and proliferation were correlated with binding affinity for Robo4. In vivo, all three T-cells inhibited tumor growth in a B16BL6 murine model, which also correlated with Robo4 binding affinities. However, growth inhibition of mouse Robo4-expressing tumors was observed only in the model with CAR-T cells with the lowest Robo4 affinity. Therefore, at high Robo4 expression, CAR-T in vitro and in vivo were no longer correlated, suggesting that clinical tumors will require Robo4 expression assays.

The Role of Slit-2 in Gestational Diabetes Mellitus and Its Effect on Pregnancy Outcome

BACKGROUND

Slit guidance ligand 2 (Slit-2), as a member of the Slit family, can regulate the inflammatory response and glucose metabolism. The purpose of this study was to explore the expression of Slit-2 in maternal peripheral blood and neonatal cord blood of gestational diabetes mellitus (GDM) patients and its potential importance in disease progression.

METHODS

This study included 57 healthy pregnant women and 61 GDM patients. The levels of Slit-2, C-reactive protein (CRP), monocyte chemoattractant protein-1 (MCP-1), C-peptide (C-P), galectin-3(Gal-3), HbA1c, fasting blood glucose (FBG) and fasting insulin (FINS) in maternal peripheral blood and neonatal cord blood were detected by ELISA. Spearman's rank correlation test was used to assess the association between peripheral Slit-2 and inflammatory indicators, insulin resistance, and pregnancy outcomes. Logistic regression analysis was used to analyze the risk factors of GDM.

RESULTS

Slit-2 levels in maternal peripheral blood and neonatal cord blood of the GDM patients were higher than those of the HC. Slit-2 levels in maternal peripheral blood and neonatal cord blood of the GDM patients were positively correlated with inflammatory factors CRP and MCP-1 levels. The level of Slit-2 in the maternal peripheral blood of the GDM patients was positively correlated with the level of homeostasis model assessment insulin resistance (HOMA-IR) and HbA1c in maternal peripheral blood, but was negatively correlated with the level of homeostasis model assessment -β (HOMA-β). We also found that the Slit-2 level in the maternal peripheral blood of the GDM patients was negatively correlated with neonatal blood glucose, positively correlated with neonatal weight and independent of neonatal total bilirubin.

CONCLUSION

Our study suggests that the abnormal increase in Slit-2 in GDM may be related to its pathogenesis, and it was correlated with neonatal blood glucose and weight in patients with GDM, suggesting that Slit-2 may be a potential biomarker of GDM.

ROBO1 protein expression is independently associated with biochemical recurrence in prostate cancer patients who underwent radical prostatectomy in Asian patients

Background

The purpose of this study is to investigate the correlation between ROBO1 expression and prostate cancer aggressiveness.

Methods

ROBO1 expression was evaluated in normal prostate epithelial cells (PrEC) and different prostate cancer cell lines by Western blot analysis. The migration and invasion of native and ROBO1 knockdown cells were evaluated using migration chambers and a Matrigel-coated membrane, respectively. Samples from 145 patients who underwent radical prostatectomy between June 2000 and June 2008, were retrieved from the paraffin files for tissue microarray (TMA) with immunohistochemical analysis. Biochemical recurrence (BCR)-free survival curves were estimated using the Kaplan-Meier and Cox regression methods in two groups of patients classified according to the degree of ROBO1 expression (low or high expression).

Results

ROBO1 is highly expressed in the prostate cancer cell lines. All ROBO1 knockdown cells (PC3, 22Rv1 and DU 145) showed markedly decreased migration and invasiveness compared to native cells. In 145 patients with radical prostatectomy, the Kaplan-Meier curves and log-rank test for BCR-free survival stratified by ROBO1 expression in organ-confined (pT2) or not (pT3), showed significant differences in 10-year survival between the ROBO1 high and low expression groups (87.2% versus 52.6% in pT2; P=0.047, 51.0% versus 36.9% in pT3; P=0.033). The multivariable-adjusted model showed a markedly increased hazard ratio (HR) in patients with high ROBO1 expression compared to the patients with low ROBO1expression in every model.

Conclusions

ROBO1 may play an important role in the migration and invasion of prostate cancer cells, and was independently associated with BCR.

Changes in SLIT2 expression are associated with the migration of human ovarian clear cell carcinoma cells

Ovarian clear cell carcinoma (OCCC) is characterized by a poor survival of patients, which is mainly due to metastasis and treatment failure. Slit guidance ligand 2 (SLIT2), a secreted protein, has been reported to modulate the migration of neural cells and human cancer cells. However, the effect of changes in SLIT2 expression on the regulation of cell migration in OCCC remains unknown. The present study examined alterations in SLIT2 expression using OCCC cell models, including low- and high-mobility SKOV3 cells, as well as OCCC tissues. DNA methylation analysis suggested that promoter hypermethylation was responsible for the low expression levels of SLIT2 in OCCC cells. The demethylating agent 5-Aza-deoxycytosine was able to restore SLIT2 expression at both the mRNA and protein levels in high-mobility SKOV3 cells that harbored the relevant methylated promoter. Overexpression of SLIT2 inhibited the migration of high-mobility OCCC cells, as well as decreased the protein expression levels of β-catenin, phosphorylated (p)AKT and snail family transcriptional repressor 1 (SNAI1). On the other hand, knockdown of SLIT2 increased the migration of low-mobility OCCC cells, and enhanced the protein expression levels of β-catenin, pAKT and SNAI1. Overall, the results of the present study provided evidence that low expression levels of SLIT2 were associated with increased OCCC cell migration, and that SLIT2 may act as a suppressor gene of cancer cell migration.

ITE promotes hypoxia-induced transdifferentiation of human pulmonary arterial endothelial cells possibly by activating transforming growth factor-β/Smads and MAPK/ERK pathways

This study aimed to investigate the transdifferentiation of human pulmonary arterial endothelial cells (HPAECs) into smooth muscle like (SM-like) cells under hypoxic conditions and reveal the role of endogenous small molecular compound 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylicacid methyl ester (ITE) in this process. HPAECs were treated by hypoxia and hypoxia + ITE with different durations. The endothelial markers (CD31 and VE-cad) and smooth muscle markers (α-SMA, SM22α, and OPN) were investigated by immunofluorescence double staining, and their expressions, along with the differentiation regulators transforming growth factor-β (TGF-β) ligands and downstream signals including TGF-β1, bone morphogenetic protein (BMP2), BMP9, Samd2/3, ERK, and p38 MAPK, were determined by Western blot analysis. The viability and proliferation of HPAECs were detected by Cell Counting Kit-8 (CCK-8) method and bromodeoxyuridine (BrdU) assays. As a result, hypoxia induced HPAECs transdifferentiation from paving-stone-like into polygonal or spindle cells, whose number increased greatly after additional ITE stimulation for 7 days. Compared with the normoxic HPAECs, the expression of endothelial markers reduced and smooth muscle markers were enhanced with the extension of hypoxia + ITE treatment, and meanwhile the cell viability increased significantly. Hypoxia could promote expression of TGF-β1 protein rather than BMP2 and BMP9, and regulate phosphorylation levels of Samd2/3, ERK and p38 MAPK in different manners. In conclusion, ITE can promote the hypoxia-induced transdifferentiation of HPAECs into SM-like cells via TGF-β/Smads and MAPK/ERK pathways.

Regulatory mechanisms of Robo4 and their effects on angiogenesis

Roundabout4 (Robo4) is a transmembrane receptor that belongs to the Roundabout (Robo) family of axon guidance molecules. Robo4 is an endothelial-specific receptor that participates in endothelial cell migration, proliferation, and angiogenesis and the maintenance of vasculature homeostasis. The purpose of this review is to summarize and analyze three main mechanisms related to the expression and function of Robo4 during developmental and pathological angiogenesis. In this review, static shear stress and the binding of transcription factors such as E26 transformation-specific variant 2 (ETV2) and Slit3 induce Robo4 expression and activate Robo4 during tissue and organ development. Robo4 interacts with Slit2 or UNC5B to maintain vascular integrity, while a disturbed flow and the expression of transcription factors in inflammatory or neoplastic environments alter Robo4 expression levels, although these changes have uncertain functions. Based on the mechanisms described above, we discuss the aberrant expression of Robo4 in angiogenesis-related diseases and propose antiangiogenic therapies targeting the Robo4 signaling pathway for the treatment of ocular neovascularization lesions and tumors. Finally, although many problems related to Robo4 signaling pathways remain to be resolved, Robo4 is a promising and potentially valuable therapeutic target for treating pathological angiogenesis and developmental defects in angiogenesis.

Targeting the SLIT/ROBO pathway in tumor progression: molecular mechanisms and therapeutic perspectives

The SLITs (SLIT1, SLIT2, and SLIT3) are a family of secreted proteins that mediate positional interactions between cells and their environment during development by signaling through ROBO receptors (ROBO1, ROBO2, ROBO3, and ROBO4). The SLIT/ROBO signaling pathway has been shown to participate in axonal repulsion, axon guidance, and neuronal migration in the nervous system and the formation of the vascular system. However, the role of the SLIT/ROBO pathway has not been thoroughly clarified in tumor development. The SLIT/ROBO pathway can produce both beneficial and detrimental effects in the growth of malignant cells. It has been confirmed that SLIT/ROBO play contradictory roles in tumorigenesis. Here, we discuss the tumor promotion and tumor suppression roles of the SLIT/ROBO pathway in tumor growth, angiogenesis, migration, and the tumor microenvironment. Understanding these roles will help us develop more effective cancer therapies.

The Expression of the SLIT-ROBO Family in Adult Patients with Acute Myeloid Leukemia

INTRODUCTION

SLIT-ROBO is a ligand-receptor family of neuronal guidance cues that has been involved in pathological and physiological angiogenesis. SLIT-ROBO expression is altered in many tumours. However, no data exist about the role of the whole family in acute myelogenous myeloid leukemia (AML).

PURPOSE

Herein, we assessed the expression of all SLIT-ROBO family in bone marrow (BM) biopsy of AML patients and control group on both protein and RNA levels.

METHODS

The paraffin-embedded tissue blocks were subjected to immunohistochemistry for SLIT1, SLIT2, SLIT3, ROBO1, ROBO2, ROBO3, and ROBO4. Microvessel density (MVD) was evaluated by CD34 immunohistochemistry. An in silico analysis using The Cancer Genome Atlas data repository was conducted for assessment of RNA level.

RESULTS

Acute myeloid leukemia patients were generally high expressers of ROBO1 and ROBO2 compared to the controls (p < 0.0001, p < 0.001, respectively). In contrast, low expression of SLIT1, SLIT2, and SLIT3 ligands has been noted more commonly in AML than in control BM samples (p < 0.0001, p = 0.003, and p = 0.001, respectively). ROBO4 expression correlated with MVD. The in silico analysis showed a poor prognostic value of high ROBO3 and low SLIT2 RNA levels (p = 0.0003 and p = 0.0008, respectively), as well as high ROBO3 and ROBO4 RNA levels in cytogenetic poor risk groups of patients (p = 0.0029 and p = 0.0003, respectively).

CONCLUSIONS

These data indicate that SLIT-ROBO family members play a role in the biology of AML. Low expression of SLIT in BM of AML patients may suggest its expression alterations in AML. Increased expression of ROBO1 and ROBO2 in AML patients suggests their participation in AML pathogenesis.

Implication of SLIT3-ROBO1/ROBO2 in granulosa cell proliferation, differentiation and follicle selection in the prehierarchical follicles of hen ovary

The SLIT/ROBO pathway has been implicated in prehierarchical follicular development of hen ovary by an intrafollicular autocrine and/or paracrine fashion. SLIT3, one of the key components of the SLIT/ROBO family, serves as a ligand that potentially interacts with the four receptors, ROBO1, ROBO2, ROBO3 and ROBO4. But the exact roles and regulatory mechanism of SLIT3 in chicken ovarian follicle development remain largely unclear. The present study was conducted to investigate the potential roles and molecular regulation of SLIT3 in granulosa cell (GC) proliferation, differentiation and follicle selection within the prehierarchical follicles of hen ovary. We found that SLIT3 interacts physically with the four ROBO receptors, but the expression of the ROBO1 and ROBO2 genes are more susceptible to the regulation of SLIT3 ligand than that of the ROBO3 and ROBO4 genes. Moreover, the siRNA-mediated knockdown of SLIT3 in the follicular GCs leads to a significant increase in cell proliferation. Conversely, overexpression of SLIT3 results in a remarkable reduction in GC proliferation. Furthermore, the overexpressed SLIT3 has notably decreased the mRNA and protein expression levels of follicle-stimulating hormone (FSHR), growth and differentiation factor 9 (GDF9), steroidogenic acute regulatory protein (STAR) and cytochrome P450 11A1 (CYP11A1) in the GCs. These results indicated that SLIT3 may play an inhibitory effect on GC proliferation, differentiation and follicle selection, and these suppressive actions of SLIT3 in the GC proliferation can be prohibited by the siRNA-mediated knockdown of ROBO1 and ROBO2 receptors. The current data provide a basis for further investigation of molecular mechanisms of SLIT3-ROBO1/2 pathway in controlling the prehierarchical follicle development of the hen ovary.

ITE inhibits growth of human pulmonary artery endothelial cells

AIM

Pulmonary arterial hypertension (PAH), a deadly disorder is associated with excessive growth of human pulmonary artery endothelial (HPAECs) and smooth muscle (HPASMCs) cells. Current therapies primarily aim at promoting vasodilation, which only ameliorates clinical symptoms without a cure. 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) is an endogenous aryl hydrocarbon receptor (AhR) ligand, and mediates many cellular function including cell growth. However, the roles of ITE in human lung endothelial cells remain elusive. Herein, we tested a hypothesis that ITE inhibits growth of human pulmonary artery endothelial cells via AhR.

MATERIALS AND METHODS

Immunohistochemistry was performed to localize AhR expression in human lung tissues. The crystal violet method and MTT assay were used to determine ITE's effects on growth of HPAECs. The AhR activation in HPAECs was confirmed using Western blotting and RT-qPCR. The role of AhR in ITE-affected proliferation of HPAECs was assessed using siRNA knockdown method followed by the crystal violet method.

RESULTS

Immunohistochemistry revealed that AhR was present in human lung tissues, primarily in endothelial and smooth muscle cells of pulmonary veins and arteries, as well as in bronchial and alveolar sac epithelia. We also found that ITE dose- and time-dependently inhibited proliferation of HPAECs with a maximum inhibition of 83% at 20 µM after 6 days of treatment. ITE rapidly decreased AhR protein levels, while it increased mRNA levels of cytochrome P450 (CYP), family 1, member A1 (CYP1A1) and B1 (CYP1B1), indicating activation of the AhR/CYP1A1 and AhR/CYP1B1 pathways in HPAECs. The AhR siRNA significantly suppressed AhR protein expression, whereas it did not significantly alter ITE-inhibited growth of HPAECs.

CONCLUSIONS

ITE suppresses growth of HPAECs independent of AhR, suggesting that ITE may play an important role in preventing excessive growth of lung endothelial cells.

GNA11 differentially mediates fibroblast growth factor 2- and vascular endothelial growth factor A-induced cellular responses in human fetoplacental endothelial cells

KEY POINTS

Fetoplacental vascular growth is critical to fetal growth. Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are two major regulators of fetoplacental vascular growth. G protein α subunit 11 (GNA11) transmits signals from many external stimuli to the cellular interior and may mediate endothelial function. It is not known whether GNA11 mediates FGF2- and VEGFA-induced endothelial cell responses under physiological chronic low O2 . In the present study, we show that knockdown of GNA11 significantly decreases FGF2- and VEGFA-induced fetoplacental endothelial cell migration but not proliferation and permeability. Such decreases in endothelial migration are associated with increased phosphorylation of phospholipase C-β3. The results of the present study suggest differential roles of GNA11 with respect to mediating FGF2- and VEGFA-induced fetoplacental endothelial function.

ABSTRACT

During pregnancy, fetoplacental angiogenesis is dramatically increased in association with rapidly elevated blood flow. Any disruption of fetoplacental angiogenesis may lead to pregnancy complications such as intrauterine growth restriction. Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are crucial regulators of fetoplacental angiogenesis. G protein α subunits q (GNAq) and 11 (GNA11) are two members of the Gαq/11 subfamily involved in mediating vascular growth and basal blood pressure. However, little is known about the roles of GNA11 alone with respect to mediating the FGF2- and VEGFA-induced fetoplacental endothelial function. Using a cell model of human umbilical cord vein endothelial cells cultured under physiological chronic low O2 (3% O2 ), we showed that GNA11 small interfering RNA (siRNA) dramatically inhibited (P < 0.05) FGF2- and VEGFA-stimulated fetoplacental endothelial migration (by ∼36% and ∼50%, respectively) but not proliferation and permeability. GNA11 siRNA also elevated (P < 0.05) FGF2- and VEGFA-induced phosphorylation of phospholipase C-β3 (PLCβ3) at S537 in a time-dependent fashion but not mitogen-activated protein kinase 3/1 (ERK1/2) and v-akt murine thymoma viral oncogene homologue 1 (AKT1). These data suggest that GNA11 mediates FGF2- and VEGFA-stimulated fetoplacental endothelial cell migration partially via altering the activation of PLCβ3.

LIFR increases the release of soluble endoglin via the upregulation of MMP14 expression in preeclampsia

Preeclampsia (PE) is a pregnancy-specific disorder that is the main cause of maternal and perinatal morbidity and mortality worldwide. Inadequate trophoblastic invasion and endothelial dysfunction in the placenta are considered the foundation of the pathogenesis of preeclampsia in which soluble endoglin (sENG) plays an antiangiogenic role in the development of PE. The leukemia inhibitory factor receptor (LIFR) has been widely studied and is highly involved in arterial injury in vivo and in the migration of cancer cells in vitro Here, we tested the hypothesis that LIFR may be correlated with preeclampsia through its regulation of the release of sENG. Our data showed that LIFR protein, the expression of which significantly decreased with the progression of pregnancy, was located in the syncytiotrophoblast and cytotrophoblast. The LIFR protein level was increased in pregnancies with preeclampsia compared with normotensive full-term pregnancies. After the overexpression of LIFR in HTR8/SVneo cells, the release of sENG as well as the migration and invasion were significantly enhanced. Moreover, we also observed that LIFR induced the expression of matrix metalloproteinase14 (MMP14) and that the knockdown or inhibition of MMP14 decreased the release of sENG, as well as increased the LIFR-induced migration and invasion of HTR8/SVneo cells. These studies demonstrated that LIFR promoted the release of sENG through MMP14 in vitro, which indicates that LIFR may be involved in the development of preeclampsia.

Preeclampsia Downregulates MicroRNAs in Fetal Endothelial Cells: Roles of miR-29a/c-3p in Endothelial Function

CONTEXT

Preeclampsia is a leading cause of fetal and maternal morbidity and mortality during pregnancy. Although the etiology of preeclampsia is unknown, preeclampsia offspring have increased risks of developing cardiovascular disorders in adulthood, implicating that preeclampsia programs fetal vasculature in utero.

OBJECTIVE

We hypothesize that preeclampsia alters expression profiles of endothelial microRNAs (miRNAs) in fetal endothelial cells and disturbs the vascular endothelial growth factor A (VEGFA)- and fibroblast growth factor 2 (FGF2)-induced endothelial function.

DESIGN AND SETTING

Unpassaged (P0) human umbilical vein endothelial cells (HUVECs) were isolated immediately after cesarean-section delivery from normotensive (NT) and preeclamptic (PE) pregnancies. Differentially expressed miRNAs between P0-HUVECs from NT and PE pregnancies were identified using a miRNA polymerase chain reaction (PCR) array and confirmed using reverse transcription quantitative PCR. To determine the function of these differentially expressed miRNAs, miRNAs of interest were knocked down in NT-HUVECs following by cell functional assays.

RESULTS

Sixteen miRNAs, including miR-29a/c-3p, were downregulated in P0-HUVECs from the PE group compared with the NT group. Bioinformatics analysis predicted the PI3K-v-akt murine thymoma viral oncogene homolog 1 (AKT) signaling pathway was dysregulated in P0-HUVECs from the PE group, which was associated with the miR-29a/c-3p downregulation. We further demonstrated that miR-29a/c-3p knockdown inhibited the VEGFA- and FGF2-induced endothelial migration as well as FGF2-induced AKT1 phosphorylation in HUVECs. However, miR-29a/c-3p knockdown did not alter the extracellular signal-regulated kinase 1/2 phosphorylation, cell proliferation, and endothelial monolayer integrity in response to VEGFA and FGF2 in HUVECs.

CONCLUSIONS

Preeclampsia-downregulated miR-29a/c-3p may impair fetal endothelial function by disturbing the FGF2-activated PI3K-AKT signaling pathway, hence inhibiting endothelial cell migration.

Quercetin Inhibits Pulmonary Arterial Endothelial Cell Transdifferentiation Possibly by Akt and Erk1/2 Pathways

This study aimed to investigate the effects and mechanisms of quercetin on pulmonary arterial endothelial cell (PAEC) transdifferentiation into smooth muscle-like cells. TGF-β1-induced PAEC transdifferentiation models were applied to evaluate the pharmacological actions of quercetin. PAEC proliferation was detected with CCK8 method and BurdU immunocytochemistry. Meanwhile, the identification and transdifferentiation of PAECs were determined by FVIII immunofluorescence staining and α-SMA protein expression. The related mechanism was elucidated based on the levels of Akt and Erk1/2 signal pathways. As a result, quercetin effectively inhibited the TGF-β1-induced proliferation and transdifferentiation of the PAECs and activation of Akt/Erk1/2 cascade in the cells. In conclusion, quercetin is demonstrated to be effective for pulmonary arterial hypertension (PAH) probably by inhibiting endothelial transdifferentiation possibly via modulating Akt and Erk1/2 expressions.

Slit2/Robo4 Signaling: Potential Role of a VEGF-Antagonist Pathway to Regulate Luteal Permeability

Introduction The corpus luteum (CL) is dependent on luteal vascular permeability, which is controlled by human chorionic gonadotropin (hCG) via vascular endothelial growth factor (VEGF). In this study we investigated the role of a potential VEGF antagonist pathway - Slit2/Robo4 - and its influence on endothelial cell adhesion. Materials and Methods Luteinized granulosa cells (LGCs) were stimulated with hCG in the absence or presence of a VEGF inhibitor. The expression of VEGF and Slit2 were measured. Human umbilical vein endothelial cells (HUVECs) were stimulated with Slit2 or VEGF, and gene expressions of cadherin 5 (CDH5) and claudin 5 (CLDN5) were measured. Following Robo4 knockdown, CDH5, CLDN5 and endothelial permeability were measured. Results Stimulation of human LGCs with hCG significantly increased VEGF while Slit2 expression was significantly suppressed. Inhibition of VEGF action after hCG stimulation did not change Slit2 suppression. Slit2 knockdown did not affect VEGF expression. While VEGF stimulation of HUVECs significantly suppressed CDH5 and CLDN5 gene expression, stimulation of HUVECs with Slit2 resulted in a significant increase in CDH5 and CLDN5. Robo4 knockdown was done, leading to downregulation of CDH5 and CLDN5 which resulted in significantly increased permeability. Conclusions Our results indicate the existence of a VEGF-antagonist pathway in the CL that decreases vascular permeability. During the functional life of the CL the pathway is suppressed by hCG. It is possible that stimulation of this pathway could be used to treat ovarian hyperstimulation syndrome.

Increased Expression of Slit2 and its Robo Receptors During Astroglial Scar Formation After Transient Focal Cerebral Ischemia in Rats

Slit2, a secreted glycoprotein, has recently been implicated in the post-ischemic astroglial reaction. The objective of this study was to investigate the temporal changes and cellular localization of Slit2 and its receptors, Robo1, Robo2, and Robo4, in a rat transient focal ischemia model induced by middle cerebral artery occlusion. We used double- and triple-immunolabeling to determine the cell-specific changes in Slit2 and its receptors during a 10-week post-ischemia period. The expression profiles of Slit2 and the Robo receptors shared overlapping expression patterns in sham-operated and ischemic striatum. Constitutive expression of Slit2 and Robo receptors was observed in striatal neurons with weak intensity, whereas in rats reperfused after ischemic insults, these immunoreactivities were increased in reactive astrocytes. Astroglial induction of Slit2 and Robo in the peri-infarct region was distinct on days 7-14 after reperfusion and thereafter increased progressively throughout the 10-week experimental period. Slit2 and Robo were prominently expressed in the perinuclear cytoplasm and main processes of reactive astrocytes forming the astroglial scar. This observation was confirmed by quantification of the mean fluorescence intensity of Slit2 and Robo receptors over reactive astrocytes localized at the edge of the infarct area. However, activated microglia/macrophages in the peri-infarct area were devoid of any specific labeling for Slit2 and Robo. Thus, our data revealed a selective and sustained induction of Slit2 and Robo in astrocytes localized throughout the astroglial scar after ischemic stroke, suggesting that Slit2/Robo signaling participates in glial scar formation and brain remodeling following ischemic injury.

Slit2‑Robo1 signaling promotes the adhesion, invasion and migration of tongue carcinoma cells via upregulating matrix metalloproteinases 2 and 9, and downregulating E‑cadherin

Whether Slit homologue 2 (Slit2) inhibits or promotes tumor cell migration remains controversial, and the role of Slit2‑Roundabout 1 (Robo1) signaling in oral cancer remains to be fully elucidated. The aim of the present study was to investigate the role of Slit2‑Robo1 signaling in the adhesion, invasion and migration of tongue carcinoma cells, and the mechanism by which Slit2‑Robo1 signaling inhibits or promotes tumor cell migration. Tca8113 tongue carcinoma cells were treated with the monoclonal anti‑human Robo1 antibody, R5, to inhibit the Slit2‑Robo1 signaling pathway, with immunoglobulin (Ig)G2b treatment as a negative control. The expression levels of Slit2 and Robo1 were determined using flow cytometry. The effects of R5 on the adhesion, invasion and migration of Tca8113 tongue carcinoma cells were investigated. Gelatin zymography was used to investigate the activity of matrix metalloproteinase 2 (MMP2) and MMP9. Western blot analysis was used to evaluate the expression levels of E‑cadherin in Tca8113 cells treated with 10 µg/ml of either R5 or IgG2b. Slit2 and Robo1 proteins were found to be expressed in the Tca8113 cells. R5 significantly inhibited the adhesion, invasion and migration of Tca8113 cells in vitro. R5 also inhibited the activities of MMP2 and MMP9, and increased the expression of E‑cadherin in the Tca8113 cells. These results suggested that Slit2‑Robo1 signaling promoted the adhesion, invasion and migration of tongue carcinoma cells by upregulating the expression levels of MMP2 and MMP9 and, downregulating the expression of E‑cadherin.

The emerging role of Slit-Robo pathway in gastric and other gastro intestinal cancers

Gastric cancer remains one of the most common cancers worldwide and one of the leading cause for cancer-related deaths. Due to the high frequency of metastasis, it is still one of the most lethal malignancies in which kinds of signaling pathways are involved in. The Roundabout (ROBO) receptors and their secreted SLIT glycoprotein ligands, which were originally identified as important axon guidance molecules, have implication in the regulation of neurons and glia, leukocytes, and endothelial cells migration. Recent researches also put high emphasis on the important roles of the Slit-Robo pathway in tumorigenesis, cancer progression and metastasis. Herein we provide a comprehensive review on the role of these molecules and their associated signaling pathway in gastric and other gastrointestinal cancers. Improved knowledge of the Slit-Robo signaling pathway in gastric carcinoma will be useful for deep understanding the mechanisms of tumor development and identifying ideal targets of anticancer therapy in gastric carcinoma.

New insights into implication of the SLIT/ROBO pathway in the prehierarchical follicle development of hen ovary

The SLIT/Roundabout (ROBO) pathway is involved in follicle development of mammalian ovary, and 2 secreted hormones activin A and inhibin A have potential roles in modulation of the SLIT/ROBO system, but the related actions remain poorly understood in bird. The aims of the present study were to examine the spatial and temporal expression of the SLIT ligand genes (SLIT1, SLIT2, and SLIT3) and their receptor ROBO1, ROBO2, ROBO3, and ROBO4 genes in various-sized prehierarchical follicles during hen ovary development and the effects of activin A and inhibin A on the expression of these genes in the cultured hen follicles. Our result demonstrated that the transcripts of the 3 SLIT genes were highly expressed in the developing follicles and expression patterns of the SLIT transcripts were different from those of ROBO genes detected by real-time quantitative reverse transcriptase PCR. Both SLIT and ROBO transcripts were predominantly expressed in oocytes and granulosa cells from the prehierarchichal follicles examined by in situ hybridization. The localization for SLIT and ROBO proteins was revealed by immunohistochemistry similar to the spatial distribution of their transcript. In cultured follicles (4 to 8 mm in diameter), the expression levels of SLIT and ROBO members are hormonally regulated by activin A (10 ng/mL) and/or inhibin A (20 ng/mL) after treatment for 24 h. However, the expression of only SLIT2, SLIT3, and ROBO3 mRNA presented a directly opposite response to activin A and inhibin A hormones. These results indicate that SLIT/ROBO pathway is implicated in the prehierarchical follicular development of the hen ovary by an intrafollicular autocrine and/or paracrine action, and is influenced by activin A and inhibin A hormones.

Expression of Robo protein in bladder cancer tissues and its effect on the growth of cancer cells by blocking Robo protein

This study aimed to detect the expression of Slit signaling protein ligand Robo protein in human bladder cancer and para-carcinoma tissue, and observe the tumor cell survival and growth by inoculating the bladder cancer cells with the blocked signaling protein into the subcutaneous tissue of nude mice. The expression of Robo protein was detected in T24 cells in human bladder uroepithelium carcinoma and cultivated human bladder uroepithelium carcinoma confirmed by pathological diagnosis. The cultivated T24 cells were coated by the protein antibody and human bladder uroepithelium carcinoma T24 tumor-bearing mice model was established. The tumor cell survival and growth were observed in the antibody coating group and non-coating group. The tumor body size was measured. The immunohistochemical detection showed that Robo protein isoforms Robo1 and Robo 4 were expressed in T24 cells of cancer tissues, paracarcinoma tissues and cultured human uroepithelium carcinoma. The expression of Robo1 was significantly higher than that of Robo4 (P<0.05). The cancer cells could be detected in nodular tumor of mice in each group. The volume of the tumor-bearing mice in the nodular tumor of the non-coating group was larger than that of anti-Robol antibody coating group and the difference was statistically significant (P<0.01). There was no significant difference in tumor volume between anti-Robo4 antibody coating group and non-coating group (P>0.05); The difference was statistically significant compared with the anti-Robo1 antibody coating group (P<0.01). In conclusion, Robo protein isoforms Robo1 and Robo4 were expressed in human bladder cancer T24 cells. To block Robo4 signal protein had little effect on the survival and growth of the transplantation tumor and to block Robo1 signal protein would seriously affect the survival and growth of the transplantation tumor, suggesting that Robo1 might play an important role in the growth and metastasis of bladder cancer, and might become a new target for the treatment of human bladder cancer and drug research.

Slit/Robo pathway: a promising therapeutic target for cancer

Axon guidance molecules, slit glycoprotein (Slit) and Roundabout receptor (Robo), have implications in the regulation of physiological processes. Recent studies indicate that Slit and Robo also have important roles in tumorigenesis, cancer progression and metastasis. The Slit/Robo pathway can be considered a master regulator for multiple oncogenic signaling pathways. Herein, we provide a comprehensive review on the role of these molecules and their associated signaling pathways in cancer progression and metastasis. Overall, the current available data suggest that the Slit/Robo pathway could be a promising target for development of anticancer drugs.

Global expression profile in low grade meningiomas and schwannomas shows upregulation of PDGFD, CDH1 and SLIT2 compared to their healthy tissue

Schwannomas and grade I meningiomas are non‑metastatic neoplasms that share the common mutation of gene NF2. They usually appear in neurofibromatosis type 2 patients. Currently, there is no drug treatment available for both tumors, thus the use of wide expression technologies is crucial to identify therapeutic targets. Affymetrix Human Gene 1.0 ST was used to test global gene expression in 22 meningiomas, 31 schwannomas and, as non-tumoral controls, 3 healthy meningeal tissues, 8 non-tumoral nerves and 1 primary Schwann cell culture. A non-stringent P-value cut-off and fold change were used to establish deregulated genes. We identified a subset of genes that were upregulated in meningiomas and schwannomas when compared to their respectively healthy tissues, including PDGFD, CDH1 and SLIT2. Thus, these genes should be thoroughly studied as targets in a possible combined treatment.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) inhibits human ovarian cancer cell proliferation

PURPOSE

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, mediates a broad spectrum of biological processes, including ovarian growth and ovulation. Recently, we found that an endogenous AhR ligand (ITE) can inhibit ovarian cancer proliferation and migration via the AhR. Here, we tested whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an exogenous AhR ligand) may exert similar anti-ovarian cancer activities using human ovarian cancer and non-cancerous human ovarian surface epithelial cells.

METHODS

Two human ovarian cancer cell lines (SKOV-3 and OVCAR-3) and one human ovarian surface epithelial cell line (IOSE-385) were used. Cell proliferation and migration activities were determined using crystal violet and FluoroBlok insert system assays, respectively. AhR protein expression was assessed by Western blotting. Expression of cytochrome P450, family 1, member A1 (CYP1A1) and member B1 (CYP1B1) mRNA was assessed by qPCR. Small interfering RNAs (siRNAs) were used to knock down AhR expression.

RESULTS

We found that TCDD dose-dependently suppressed OVCAR-3 cell proliferation, with a maximum effect (~70% reduction) at 100 nM. However, TCDD did not affect SKOV-3 and IOSE-385 cell proliferation and migration. The estimated IC50 of TCDD for inhibiting OVCAR-3 cell proliferation was 4.6 nM. At 10 nM, TCDD time-dependently decreased AhR protein levels, while it significantly increased CYP1A1 and CYP1B1 mRNA levels in SKOV-3, OVCAR-3 and IOSE-385 cells, indicating activation of AhR signaling. siRNA-mediated AhR knockdown readily blocked TCDD-mediated suppression of OVCAR-3 cell proliferation.

CONCLUSION

Our data indicate that TCDD can suppress human ovarian cancer cell proliferation via the AhR signaling pathway and that TCDD exhibits an anti-proliferative activity in at least a subset of human ovarian cancer cells.

Prognostic implications of SLIT and ROBO1 expression in gallbladder cancer

SLIT, a secretory glycoprotein, and its receptor roundabout (ROBO) are expressed in several types of cancer and have been implicated in tumor angiogenesis. The purpose of this study was to determine the prognostic implications of SLIT and ROBO1 expression and their association with clinicopathologic characteristics in gallbladder cancer. A retrospective analysis of 109 consecutive patients who underwent primary gallbladder cancer resection was conducted. Univariate and multivariate models were used to analyze the effect of clinicopathologic factors on survival. Expression of SLIT and ROBO1 was evaluated by immunohistochemistry, and their association with clinicopathologic characteristics was analyzed using mean testing. Multivariate linear regression analysis was also applied to investigate the independent predictors of ROBO1 expression. Seventy-five patients were included in the post-resection survival analysis, with 1-year and 3-year overall survival rates of 60 and 40 %, respectively. Univariate analysis revealed that pN classification, pT classification, pM classification, liver involvement, perineural invasion, TNM staging, Nevin staging, and microscopic resection margins affect prognosis. Multivariate analysis confirmed that pN classification, liver involvement, and perineural invasion are independent prognostic factors. In the mean tests of 109 cases, the mean difference of SLIT immunoreactivity was significant according to the presence of gallstones (P = 0.003) and liver involvement (P = 0.005), while the mean difference of ROBO1 immunoreactivity was significant according to liver involvement (P < 0.001), TNM staging (P < 0.001), and Nevin staging (P < 0.001). Multivariate analysis of ROBO1 immunoreactivity showed that SLIT immunoreactivity and TNM stage (adjusted R (2) = 0.203) or SLIT immunoreactivity and Nevin stage (adjusted R (2) = 0.195) were independent predictors of ROBO1 expression. pN classification, liver involvement, perineural invasion, and pathologic stage are significant prognostic factors for gallbladder cancer survival. SLIT expression is associated with cholelithiasis and liver involvement, and ROBO1 expression is associated with liver involvement and pathologic stage. In addition, SLIT expression and pathologic stage predict ROBO1 expression independently.

Subcellular distribution patterns and elevated expression of GNA11 and GNA14 proteins in the lungs of humans with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH), a progressive and devastating disease, is characterized by abnormal proliferation of pulmonary artery endothelial and smooth muscle cells. GTP-binding protein subunits, GNA11 and GNA14, transmembrane and intracellular signaling molecules, participate in the regulating endothelial function and vascular development. We followed the expression of GNA11 and GNA14 in human lungs in control and PAH patients using immunohistochemical and Western blot analyses. Both GNA11 and GNA14 were expressed in lung tissue, primarily in artery endothelial and smooth muscle cells. Expression was more pronounced in PAH lung tissues compared with controls. Using immunocytochemistry and laser scanning confocal microscopy, the subcellular distribution of GNA11 and GNA14 in human pulmonary arterial endothelial (HPAECs) and smooth muscle (HPASMCs) cells in culture was investigated. GNA11 was predominantly localized in the cytoplasm and nucleus of HPASMCs, but it was only found in the cytoplasm of HPAECs. On the other hand, GNA14 immunolocalized to the nucleus and cytoplasm of both HPAECs and HPASMCs. Based on bioinformatic analyses, nuclear localization signal and transmembrane topology confirm the different subcellular distributions of GNA11 and GNA14. The data suggest that GNA11 and GNA14 are related to PAH pathogenesis, and help further functional studies of these proteins in this severe disease.

Expression of G-protein subunit α-14 is increased in human placentas from preeclamptic pregnancies

G-proteins mediate cellular function upon interaction with G-protein coupled receptors. Of the 16 mammalian G-protein α subunits identified, G-protein subunit α-11 (GNA11) and -14 (GNA14) have been implicated in modulating hypertension and endothelial function. However, little is known about their expression and roles in human placentas. Here, we examined GNA11 and GNA14 protein expression in first trimester (FT), normal term (NT), and severe preeclamptic (sPE) human placentas as well as in NT human umbilical cords. We found that GNA11 and GNA14 were immunolocalized primarily in trophoblasts, villous stromal cells, and endothelial cells in placentas as well as in endothelial and/or smooth muscle cells of the umbilical cord artery and vein. Western blotting revealed that the GNA14, but not GNA11, protein levels were increased (2.5-2.9 fold; p<0.01) in sPE vs. NT placentas. GNA11 protein was detected only in NT, but not FT, placentas, whereas GNA14 protein levels were increased (7.7-10.6 fold; p<0.01) in NT vs. FT placentas. Thus, GNA11 and GNA14 may mediate the function of several cell types in placentas. Moreover, the high expression of GNA14 in sPE placentas may also imply its importance in sPE pregnancies as in the other hypertension-related disorders.

Enhanced cellular responses and distinct gene profiles in human fetoplacental artery endothelial cells under chronic low oxygen

Fetoplacental endothelial cells are exposed to oxygen levels ranging from 2% to 8% in vivo. However, little is known regarding endothelial function within this range of oxygen because most laboratories use ambient air (21% O2) as a standard culture condition (SCN). We asked whether human umbilical artery endothelial cells (HUAECs) that were steadily exposed to the physiological chronic normoxia (PCN, 3% O2) for ∼20-25 days differed in their proliferative and migratory responses to FGF2 and VEGFA as well as in their global gene expression compared with those in the SCN. We observed that PCN enhanced FGF2- and VEGFA-stimulated cell proliferation and migration. In oxygen reversal experiments (i.e., when PCN cells were exposed to SCN for 24 h and vice versa), we found that preexposure to 21% O2 decreased the migratory ability, but not the proliferative ability, of the PCN-HUAECs in response to FGF2 and VEGFA. These PCN-enhanced cellular responses were associated with increased protein levels of HIF1A and NOS3, but not FGFR1, VEGFR1, and VEGFR2. Microarray analysis demonstrated that PCN up-regulated 74 genes and down-regulated 86, 14 of which were directly regulated by hypoxia-inducible factors as evaluated using in silico analysis. Gene function analysis further indicated that the PCN-regulated genes were highly related to cell proliferation and migration, consistent with the results from our functional assays. Given that PCN significantly alters cellular responses to FGF2 and VEGFA as well as transcription in HUAECs, it is likely that we may need to reexamine the current cellular and molecular mechanisms controlling fetoplacental endothelial functions, which were largely derived from endothelial models established under ambient O2.

Prostaglandin F2α upregulates Slit/Robo expression in mouse corpus luteum during luteolysis

Prostaglandin F2 α (PGF2 α) is a key factor in the triggering of the regression of the corpus luteum (CL). Furthermore, it has been reported that Slit/Robo signaling is involved in the regulation of luteolysis. However, the interactions between PGF2 α and Slit/Robo in the progression of luteolysis remain to be established. This study was designed to determine whether luteolysis is regulated by the interactions of PGF2 α and Slit/Robo in the mouse CL. Real-time PCR and immunohistochemistry results showed that Slit2 and its receptor Robo1 are highly and specifically co-expressed in the mouse CL. Functional studies showed that Slit/Robo participates in mouse luteolysis by enhancing cell apoptosis and upregulating caspase3 expression. Both in vitro and in vivo studies showed that PGF2 α significantly increases the expression of Slit2 and Robo1 during luteolysis through protein kinase C-dependent ERK1/2 and P38 MAPK signaling pathways, whereas an inhibitor of Slit/Robo signaling significantly decreases the stimulating effect of PGF2 α on luteolysis. These findings indicate that Slit/Robo signaling plays important roles in PGF2 α-induced luteolysis by mediating the PGF2 α signaling pathway in the CL.

An endogenous aryl hydrocarbon receptor ligand inhibits proliferation and migration of human ovarian cancer cells

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor mediates many biological processes. Herein, we investigated if 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE, an endogenous AhR ligand) regulated proliferation and migration of human ovarian cancer cells via AhR. We found that AhR was widely present in many histotypes of ovarian cancer tissues. ITE suppressed OVCAR-3 cell proliferation and SKOV-3 cell migration in vitro, which were blocked by AhR knockdown. ITE also suppressed OVCAR-3 cell growth in mice. These data suggest that the ITE might potentially be used for therapeutic intervention for at least a subset of human ovarian cancer.

SLIT2 inhibits cell migration in colorectal cancer through the AKT-GSK3β signaling pathway

PURPOSE

Colorectal cancer is a common malignancy and one of the major causes of cancer-related deaths worldwide. Similar to other human cancers, tumor metastasis is the biggest obstacle in the clinical treatment of colorectal cancer. In this study, we explored the functional role of SLIT2 in colon tumor metastasis and the relevant molecular mechanisms.

METHODS

Immunohistochemistry, Western blotting, and quantitative reverse transcription-polymerase chain reaction were used to measure SLIT2 expression in colorectal tumor tissues in the presence or absence of metastasis. Wound-healing assays, Transwell assays, Western blotting, and immunofluorescence assays were used to examine the effects of SLIT2 on SW480 and NCM460 cell migration and the epithelial-to-mesenchymal transition (EMT). An AKT inhibitor was introduced to examine the mechanism underlying SLIT2-mediated suppression of NCM460 cell migration.

RESULTS

Higher SLIT2 expression was detected in metastasis-positive tumor tissues, and this upregulation was beneficial for the overall survival of patients with colorectal cancer. Either the addition of purified SLIT2 or overexpression of SLIT2 inhibited SW480 cell migration, whereas the depletion of SLIT2 with shRNA enhanced the migratory ability of NCM460 cells. Meanwhile, SLIT2 depletion also induced β-catenin accumulation and altered the expression levels of several molecules related to EMT in NCM460 cells. AKT inhibition abrogated the effects of SLIT2 depletion on EMT and migration in NCM460 cells.

CONCLUSIONS

SLIT2 suppresses colon tumor metastasis, and it exerts its suppressive activity against colorectal cancer metastasis by restraining AKT signaling and EMT, thus making it a potential clinical prognosis marker in colorectal cancer.

Estradiol 17β and its metabolites stimulate cell proliferation and antagonize ascorbic acid-suppressed cell proliferation in human ovarian cancer cells

Estradiol 17β (E2β) and ascorbic acid (AA) have been implicated in cancer progression. However, little is known about the actions of biologically active metabolites of E2β, 2-hydroxyestradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 2-methoxyestradiol (2ME2), and 4-methoxyestradiol (4ME2) synthesized sequentially by cytochrome P450, family 1, subfamily A (CYP1A1) and B (CYP1B1), polypeptide 1, and catechol-O-methyltransferase (COMT) on ovarian cancer. Herein, we examined the expression of CYP1A1, CYP1B1, COMT, and estrogen receptor α (ERα) and β (ERβ) in human ovarian surface epithelial (IOSE-385) and cancer cell lines (OVCAR-3, SKOV-3, and OVCA-432). We also investigated the roles of E2β, 2OHE2, 4OHE2, 2ME2, and 4ME2 in cell proliferation, and their interactive effects with AA on ovarian cells. We found the expression of CYP1A1, CYP1B1, COMT, ERα, and ERβ in most cell lines tested. Treating cells with physiological concentrations of E2β and its metabolites promoted (13%-42% of the control) IOSE-385 and OVCAR-3 proliferation. The ER blockade inhibited IOSE-385 (∼76%) and OVCAR-3 (∼87%) proliferative response to E2β but not to its metabolites. The ERα blockade inhibited (∼85%) E2β-stimulated OVCAR-3 proliferation, whereas ERβ blockade attenuated (∼83%) E2β-stimulated IOSE-385 proliferation. The AA at ≥250 μmol/L completely inhibited serum-stimulated cell proliferation in all cell lines tested; however, such inhibition in IOSE-385, OVCAR-3, and OVCA-432 was partially (∼10%-20%) countered by E2β and its metabolites. Thus, our findings indicate that E2β and its metabolites promote cell proliferation and antagonize the AA-suppressed cell proliferation in a subset of ovarian cancer cells, suggesting that blocking the actions of E2β and its metabolites may enhance AA's antiovarian cancer activity.

Transcriptional and functional adaptations of human endothelial cells to physiological chronic low oxygen

Endothelial cells chronically reside in low-O2 environments in vivo (2%-13% O2), which are believed to be critical for cell homeostasis. To elucidate the roles of this physiological chronic normoxia in human endothelial cells, we examined transcriptomes of human umbilical vein endothelial cells (HUVECs), proliferation and migration of HUVECs in response to fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA), and underlying signaling mechanisms under physiological chronic normoxia. Immediately after isolation, HUVECs were cultured steadily under standard cell culture normoxia (SCN; 21% O2) or physiological chronic normoxia (PCN; 3% O2) up to 25 days. We found that PCN up-regulated 41 genes and down-regulated 21 genes, 90% of which differed from those previously reported from HUVECs cultured under SCN and exposed to acute low O2. Gene ontology analysis indicated that PCN-regulated genes were highly related to cell proliferation and migration, consistent with the results from benchtop assays that showed that PCN significantly enhanced FGF2- and VEGFA-stimulated cell proliferation and migration. Interestingly, preexposing the PCN cells to 21% O2 up to 5 days did not completely diminish PCN-enhanced cell proliferation and migration. These PCN-enhanced cell proliferations and migrations were mediated via augmented activation of MEK1/MEK2/ERK1/ERK2 and/or PI3K/AKT1. Importantly, these PCN-enhanced cellular responses were associated with an increase in activation of VEGFR2 but not FGFR1, without altering their expression. Thus, PCN programs endothelial cells to undergo dramatic changes in transcriptomes and sensitizes cellular proliferative and migratory responses to FGF2 and VEGFA. These PCN cells may offer a unique endothelial model, more closely mimicking the in vivo states.

Human placental expression of SLIT/ROBO signaling cues: effects of preeclampsia and hypoxia

Preeclampsia is characterized by dysfunctional endothelium and impaired angiogenesis. Recent studies suggest that the neuronal guidance SLIT/ROBO system regulates tumor angiogenesis. This study investigated if SLIT and ROBO are differentially expressed in healthy term and preeclamptic placentas and if hypoxia regulates SLIT and ROBO expression in placental trophoblast and endothelial cells. Total RNA and protein were extracted from placental tissues of healthy term (n = 5) and preeclamptic (n = 6) pregnancies and used for SLIT/ROBO expression analyses with reverse transcription-polymerase chain reaction (RT-PCR), real-time quantitative-PCR, and immunoblotting. Paraffin-embedded tissues were processed to localize SLIT/ROBO proteins in placental villi by immunohistochemistry. BeWo choriocarcinoma cells and human umbilical vein endothelial cells (HUVEC) were treated with 2% or 10% oxygen or the hypoxia mimetic deferoxamine mesylate (100 μM) to test if hypoxia regulates SLIT/ROBO expression. SLIT2, SLIT3, ROBO1, and ROBO4 mRNA and proteins were detected in the placenta. SLIT2 and ROBO1 proteins localized in the syncytiotrophoblast, and SLIT3, ROBO1, and ROBO4 in capillary endothelium of the placental villi. Levels of ROBO1 and ROBO4 as well as sFLT1 (soluble fms-like tyrosine kinase-1) proteins were significantly greater in preeclamptic placentas compared to normal controls. Hypoxia significantly increased both mRNA and protein levels of SLIT2 in BeWo cells and of SLIT3, ROBO1, and ROBB4 in HUVEC. Thus, trophoblast and endothelial coexpression of SLIT/ROBO suggests an autocrine/paracrine regulatory system for regulating placental function. Differential expression of SLITs and ROBOs in healthy term and preeclamptic placentas and hypoxia regulation of their expressions in placental cells implicate a potential pathophysiological role for this system in preeclampsia.

Recent progress in histochemistry and cell biology

Studies published in Histochemistry and Cell Biology in the year 2011 represent once more a manifest of established and newly sophisticated techniques being exploited to put tissue- and cell type-specific molecules into a functional context. The review is therefore the Histochemistry and Cell Biology's yearly intention to provide interested readers appropriate summaries of investigations touching the areas of tissue biology, developmental biology, the biology of the immune system, stem cell research, the biology of subcellular compartments, in order to put the message of such studies into natural scientific-/human- and also pathological-relevant correlations.