Analysis of gene expression identifies candidate markers and pathways in pre-eclampsia

Pre-eclampsia is a serious multisystem disorder and causes significant increase in both maternal and foetal morbidity and perinatal mortality globally. Due to the limited understanding of the molecular mechanism of pre-eclampsia, the current study conducted bioinformatic analyses to screen key regulators involved in pre-eclampsia. The gene expression profiling dataset GSE44711 containing 8 early-onset pre-eclampsia placentas and 8 gestational-age-matched control placentas was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened by limma software package, which were then subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis on the Database for Annotation, Visualization, and Integrated Discovery website. Finally, protein-protein interaction network was constructed using the Search Tool for the Retrieval of Interacting Genes database. In total, 192 DEGs including 106 upregulated and 86 downregulated genes were obtained. Proteoglycan 2 and podoplanin were the most significantly up- and downregulated genes, respectively. In addition, three potential pathways and their related DEGs: spermidine/spermine N1-acetyltransferase 1, amiloride-binding protein 1 and adenosylmethionine decarboxylase 1 were associated with arginine and proline metabolism. Vascular endothelial growth factor C; phosphatidylinositol-4, 5-bisphosphate 3-kinase, catalytic subunit beta; collagen, type I, alpha 1 (COL1A1); and fibronectin 1 (FN1) were associated with focal adhesion. COL6A1 as well as COL1A1 and FN1 were involved in extra-cellular matrix-receptor interaction. The current study identified several potential genes and three pathways which may be considered as candidate targets for diagnosis and therapy of pre-eclampsia.

Incoherent feedforward control governs adaptation of activated ras in a eukaryotic chemotaxis pathway

Adaptation in signaling systems, during which the output returns to a fixed baseline after a change in the input, often involves negative feedback loops and plays a crucial role in eukaryotic chemotaxis. We determined the dynamical response to a uniform change in chemoattractant concentration of a eukaryotic chemotaxis pathway immediately downstream from G protein-coupled receptors. The response of an activated Ras showed near-perfect adaptation, leading us to attempt to fit the results using mathematical models for the two possible simple network topologies that can provide perfect adaptation. Only the incoherent feedforward network accurately described the experimental results. This analysis revealed that adaptation in this Ras pathway is achieved through the proportional activation of upstream components and not through negative feedback loops. Furthermore, these results are consistent with a local excitation, global inhibition mechanism for gradient sensing, possibly with a Ras guanosine triphosphatase-activating protein acting as a global inhibitor.

Abstract P5-06-04: Nicastrin Reveals Gamma-Secretase Independent Function in Breast Cancer Cells and Can Be Targeted by a Blocking Monoclonal Antibody To Reduce Breast Cancer Cell Proliferation and Invasion

BACKGROUND: Nicastrin (NCT) is a structural and functional part of the gamma-secretase (GS) enzyme, implicated in tumorigenesis and resistance to treatment in multiple cancer types. However, its mechanism(s) of action and biological functions are poorly understood. We investigated functional and biological effects of inhibiting NCT in breast cancer (BC)cells by means of gene silencing and blocking antibodies, as well as the prognostic value of NCT expression in BC tissue. METHODS: NCT siRNA (Dahrmacon) was used at 40nM. A polyclonal antibody (pcAb) against NCT extracellular domain was developed at Biogenes (GE), and anti-NCT monoclonal antibodies (mAbs) at Genovac (GE). We tested the Abs for their ability to recognize endogenous NCT in BC cells by FACS and Western blot. Best Abs were tested in vitro, using a transwell cell invasion assay and proliferation assay. Anti-NCT Ab (Sigma, N1660) was used for immunohistochemistry (IHC) staining of BC tissues (n = 1050). Cases were scored as NCT negative (0), 1+, 2+ or 3+. Kaplan Meier analysis was used to investigate impact of NCT expression on survival. Illumina (Agilent) oligonucleotide arrays were used to investigate NCT siRNA effects on gene expression in BC cells. Both PcAb and mAbs recognized endogenous NCT in BC cells. In vitro, blocking NCT in MDA-MB231 BC cells with the PcAb, reduced cell proliferation in a dose dependent manner; by 50% and 70% at concentrations of 50μg/ml and 100μg/ml, respectively. mAbs reduced proliferation by 50% (clones 2H6 and 10C5) and 70% clone 10C11, (P<0.01). In transwell cell invasion assay, anti-NCT pcAb induced a dose dependent reduction of invasion, by 35% at the 5μg/ml, peaking at > 60% reduction at 50μg/ml (P<0.001). mAbs reduced cell invasion by 40-50% (clone 10C5 and 10C11) and by >65% (clone 2H6) (P<001). IHC data showed that NCT was highly expressed (2+, 3+) in 47.5% of BC tissues. High NCT expression correlated with worse overall survival (OS) in ERnegative patients (p=0.05). To elucidate the effects of NCT loss, compared to those induced by GSIs or silencing Notch receptors, we examined cDNA from MDA231 treated independently with NCT, Notch1, Notch2, Notch4 siRNAs and GSI MK-003, on Illumina expression arrays. Thirteen of the 18 genes maximally affected by GSI were similarly affected by NCT siRNA. NCT knockdown also affected 1745 other genes that by large were not affected by GSI or Notch knockdowns. This suggests that NCT has GS-and Notch-independent cellular functions and may have different biological properties as a therapeutic target than GS. Among NCT siRNA affected genes, some are tumor suppressors: CST4 increased 8 fold; pro-invasive genes like GNG11 decreased 4 fold; cell adhesion genes: CTGF increased 4.5 fold etc.

CONCLUSIONS: NCT is overexpressed in 47.5% of BC cases where it infers adverse OS in the ER-vecohort of patients. Anti-NCT mAbs recognize endogenous NCT in BC cells and reduce BC cell proliferation and invasion. Silencing NCT in invasive BC cells induces extensive gene expression changes that only partially overlap with those caused by GSIs or Notch siRNAs. We conclude that NCT has GS-independent functions in BC cells and that an anti-NCT mAb may be a promising therapeutic approach for invasive BC.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-06-04.

Computational model for cell morphodynamics

We develop a computational model, based on the phase-field method, for cell morphodynamics and apply it to fish keratocytes. Our model incorporates the membrane bending force and the surface tension and enforces a constant area. Furthermore, it implements a cross-linked actin filament field and an actin bundle field that are responsible for the protrusion and retraction forces, respectively. We show that our model predicts steady state cell shapes with a wide range of aspect ratios, depending on system parameters. Furthermore, we find that the dependence of the cell speed on this aspect ratio matches experimentally observed data.

Increased basal insulin secretion in Pdzd2-deficient mice

Expression of the multi-PDZ protein Pdzd2 (PDZ domain-containing protein 2) is enriched in pancreatic islet beta cells, but not in exocrine or alpha cells, suggesting a role for Pdzd2 in the regulation of pancreatic beta-cell function. To explore the in vivo function of Pdzd2, Pdzd2-deficient mice were generated. Homozygous Pdzd2 mutant mice were viable and their gross morphology appeared normal. Interestingly, Pdzd2-deficient mice showed enhanced glucose tolerance in intraperitoneal glucose tolerance tests and their plasma insulin levels indicated increased basal insulin secretion after fasting. Moreover, insulin release from mutant pancreatic islets was found to be twofold higher than from normal islets. To verify the functional defect in vitro, Pdzd2 was depleted in INS-1E cells using two siRNA duplexes. Pdzd2-depleted INS-1E cells also displayed increased insulin secretion at low concentrations of glucose. Our results provide the first evidence that Pdzd2 is required for normal regulation of basal insulin secretion.

Inhibiting nicastrin (NCT) stabilizes expression of e-cadherin and has potential in inducing mesenchymal to epithelial transition in breast cancer (BC)

Abstract #3066

Introduction: NCT is a member of the Gamma Secretase (GS) enzyme complex, responsible for activating multiple substrates (Notch proteins, Her4, E-cadherin , CD44 etc.), implicated in BC development and progression from primary tumour to metastasis. E-cadherin (E-cad) is a key protein regulating cell-to-cell adhesion. Loss of E-cad is a central feature of Epithelial-to-Mesenchymal (EMT) transition enabling cell migration and invasion, while restoration of E-cad expression indicates a less malignant cell phenotype.
 Materials and Methods: MCF-7 and MDA-MB-231 BC cell lines were used to investigate expression of NCT by Western Blot (WB) and RT-Q-PCR. Paraffin embedded BC tissue samples (n=126), 10 benign breast lesions (fibroadenoma) and 40 normal breast tissue specimens were analysed for NCT expression by Immunohistrochemistry (IHC). NCT was transiently silenced in vitro by siRNA and expression of E-cad, Beta-Catenin, Snail1 were analysed by WB and RT-Q-PCR. A commercially available kit was used to measure GS activity in vitro. Transmitted light microscopy was used to monitor cell motility using a model of a stable NCT knockout (KO) in mouse embryonic fibroblast (MEF) cells.
 Results: NCT was not expressed or was weakly expressed in normal breast tissue by IHC. Strikingly, NCT was highly expressed only in the myoepithelial layer of all 10 fibroadenomas analysed, while epithelial layer remained negative of weakly NCT positive (+). Breast carcinomas were graded as NCT 1+, 2+ or 3+. NCT siRNA (72 h) resulted in >90% reduction of both NCT mRNA and protein levels, as well as >50% reduction in GS activity in both MDA-MB-231 and MCF-7 cell lines. NCT siRNA did not affect E-cad, Beta-Catenin or Snail1 mRNA levels in these cell lines. However, NCT siRNA resulted in cellular redistribution of E-cad to the cell membrane, as visualized by immunofluorescence, and an increase in E-cad protein levels by WB in MCF-7 cells. The transient NCT silencing at 72 h did not result in change of morphology in MDA-MB-231 cells. Cell motility was, however, reduced by 20%: (0.01 µm/sec in parental MDA-MB-231 vs 0.008 µm/sec in MDA-MB-231 NCT siRNA cells). Stable NCT KO caused a notable change in cell phenotype, converting a spindle like wild type MEFs to rounded epitheloid-like morphology, coupled with a marked increase of E-cad localized to the membrane. Furthermore, cell motility was reduced by 3 fold in NCT KO MEFs (0.008 µm/sec in wild type MEFs vs 0.0025um/sec in the NCT KO MEFs).
 Conclusion: NCT is up-regulated in BC as compared to normal breast tissue. NCT is strongly expressed only in the myoepithelial cell compartment of breast fibroadenomas, suggesting possible involvement of NCT in EMT. Inhibiting NCT stabilizes E-cadherin protein levels in BC cells, at the post-translational level. Inhibiting NCT in BC may represent a potential strategy to reduce BC invasiveness and metastasis.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3066.

Dynamic studies of scaffold-dependent mating pathway in yeast

The mating pathway in Saccharomyces cerevisiae is one of the best understood signal transduction pathways in eukaryotes. It transmits the mating signal from plasma membrane into the nucleus through the G-protein coupled receptor and the mitogen-activated protein kinase (MAPK) cascade. According to current understanding of the mating pathway, we construct a system of ordinary differential equations to describe the process. Our model is consistent with a wide range of experiments, indicating that it captures some main characteristics of the signal transduction along the pathway. Investigation with the model reveals that the shuttling of the scaffold protein and the dephosphorylation of kinases involved in the MAPK cascade cooperate to regulate the response upon pheromone induction and to help preserve the fidelity of the mating signaling. We explored factors affecting the dose-response curves of this pathway and found that both negative feedback and concentrations of the proteins involved in the MAPK cascade play crucial roles. Contrary to some other MAPK systems where signaling sensitivity is being amplified successively along the cascade, here the mating signal is transmitted through the cascade in an almost linear fashion.

Arp2/3 complex-mediated actin polymerisation occurs on specific pre-existing networks in cells and requires spatial restriction to sustain functional lamellipod extension

The classical Arp2/3-mediated dendritic network defines the cytoskeleton at the leading edge of crawling cells, and it is generally assumed that Arp2/3-mediated actin polymerization generates the force necessary to extend lamellipods. Our previous work suggested that successful lamellipod extension required not only free barbed ends for actin polymerization but also a proper ultrastructural organization of the cytoskeleton. To further explore the structural role of the Arp2/3 complex-mediated networks in lamellipod morphology and function, we performed a detailed analysis of the ultrastructure of the Arp2/3-mediated networks, using the WA domains of Scar and WASp to generate mislocalised Arp2/3 networks in vivo, and to reconstruct de novo Arp2/3-mediated actin nucleation and polymerization on extracted cytoskeletons. We present here evidence that spatially unrestricted Arp2/3-mediated networks are intrinsically three-dimensional and multilayered by nature and, as such, cannot sustain significant polarized extension. Furthermore, such networks polymerize only at preferred locations in extracted cells, corresponding to pre-existing Arp2/3 networks, suggesting that the specific molecular organization of the actin cytoskeleton, in terms of structure and/or biochemical composition, dictates the location of Arp2/3 complex-mediated actin polymerization. We propose that successful lamellipod extension depends not only on localized actin polymerization mediated through local signalling, but also on spatial restriction of the Arp2/3 complex-mediated nucleation of actin polymerization, both in terms of location within the cell and ultrastructural organization of the resulting network.

Radiation doses to patients during selected CT procedures at four hospitals in Tanzania

The dose characteristics of CT scanners from local scanning protocols were investigated on the basis of questionnaire information provided by four hospitals conducting CT procedures in Tanzania. The information included scanner model, scanner manufacturer, number of most frequent CT examinations and the employed scanning parameters to previously diagnosed patients. For each scan technique, patient doses were estimated in terms of computerized tomography dose index, dose length product and effective dose using the software developed by the ImPACT scan group in conjunction with the NRPB conversion coefficients data. The results show that the mean CTDI_w,100, DLP and effective dose ranged from 8.5 +/- 2.8 to 79.3 +/- 23.7mGy, 145 +/- 5 to 1400 +/- 812.5 mGy cm and 3 +/- 2.3 to 15.7 +/- 10.4 mSv, respectively. On average, the observed CT doses are however roughly higher than the reported literature data such as 30 to 60 mGy, 570 to 1050 mGy cm and 2.4 to 11.7 mSv recommended by European Commission for similar CT examinations. The higher dose levels, which are possibly associated with significant risks, justify extensive similar studies at the national level in order to unify different approaches towards optimisation of CT examinations. In pursue of this noble objective, the need to train the radiology personnel, establish and using protocols and continuously monitor the performance of CT equipment to control patient CT doses is of utmost importance.

Distribution and regulation of expression of serum- and glucocorticoid-induced kinase-1 in the rat kidney

The serum- and glucocorticoid-induced kinase-1 (sgk1) increases the activity of a number of epithelial ion channels and transporters. The present study examines the distribution and subcellular localization of sgk1 protein in the rat kidney and the regulation of levels of expression induced by steroids. The results indicate that the kidney expresses predominantly the sgk1 isoform with a distribution restricted to the thick ascending limb of Henle, distal convoluted, connecting and cortical collecting tubules. Within cells, sgk1 strongly associates with the microsomal fraction of homogenates and it colocalizes with the Na+,K+-ATPase to the basolateral membrane. Analysis of the levels of expression of sgk1 by Western blotting and immunohistochemistry indicates constitutive high expression under basal conditions. Approximately half of the basal level is maintained by glucocorticoids whereas physiological fluctuations of aldosterone produce minor changes in sgk1 abundance in adrenal-intact animals. These results do not support the notion that physiological changes of aldosterone concentration turn the expression of sgk1 'on and off' in the mammalian kidney. Additionally, localization of sgk1 to the basolateral membrane indicates that the effects mediated by sgk1 do not require a direct interaction with the ion channels and transporters whose activity is modulated, since most of these proteins are located in the apical membrane of renal epithelial cells.

[Predictive value of combined application of umbilical artery color Doppler velocimetry, nonstress testing and ultrasonography in monitoring umbilical cord entanglement]

OBJECTIVE

To explore the predictive value of combined application of umbilical artery color Doppler flow monitoring (CDFI), nonstress testing (NST) and ultrasonography in monitoring umbilical cord entanglement.

METHODS

1 860 cases of pregnant women between gestational ages of 37 approximately 42 weeks were studied 1 approximately 2 weeks before delivery by CDFI, nonstress testing (NST) and ultrasonography to monitor umbilical cord entanglement.

RESULTS

The prevalence rate of umbilical cord entanglement was 23.23% (432/1 860). Positive predictive value and negative predictive value were 95.4 % (412/432) and 98.6% (1 408/1 428) respectively. The rate of accuracy was 97.8% (1 820/1 860). The rate of fetal distress among the fetuses with umbilical cord round the body or four limbs was 85.29% (23/34) and the incidence of cesarean section in this group was 88.28% (30/34). The rate of fetal distress among the fetuses with umbilical cord round the neck was 13.06% (52/398) and the incidence of cesarean section in this group was 44.94% (178/398). The rates of fetal distress and cesarean section were significantly higher in the group with umbilical cord around the body or four limbs than in the group with umbilical cord around the neck (chi(2) = 107.27 and 23.76 respectively, P < 0.001). The systolic/diastolic (S/D) ratio was basically in normal ranges in the group with the umbilical cord round the neck. In cardiotopography (CTG), umbilical cord entanglement mainly showed variable deceleration (VD), early deceleration (ED), nonreaction on NST, and late deceleration (LD) on oxytocin challenge test (OCT). Prolonged fetal heart rate deceleration (PD) could be seen in the group with umbilical cord around the body or four limbs.

CONCLUSION

The combined application of umbilical artery color Doppler velocimetry, nonstress testing and ultrasonography have an important auxiliary value in monitoring umbilical cord entanglement. It remarkably increases the positive predictive rate as a valuable reference for the choice of delivery form.

A novel function of B lymphocytes from normal mice to suppress autoimmunity in (NZB x NZW)F1 mice

In systemic autoimmune-prone (NZB x NZW)F1 (NZB/W F1) mice, B-cell abnormalities characterized by hypergammaglobulinaemia accompanying autoantibodies have been thought to be a main cause of the disease. To examine a possible regulatory role of B cells in the disease manifestations, we injected, intravenously (i.v.), normal or autoimmune B cells into non-irradiated NZB/W F1 mice. The injection of splenic B cells from major histocompatibility (MHC)-matched or allogeneic normal mice caused a marked decrease in serum immunoglobulin G (IgG) levels of autoantibodies, delayed the appearance of proteinuria and prolonged life span, whereas treatment with splenic B cells from NZB/W F1 or X-linked immunodeficient (Xid) mice failed to suppress the autoimmunity. Moreover, in vitro polyclonal antibody responses to lipopolysaccharide (LPS) of NZB/W F1-derived B cells from the treated mice were markedly reduced. Interestingly, the treatment of NZB/W F1 mice at 16, 18 and 20 or at 20, 22 and 24 weeks of age was more effective than that at 6, 8 and 10 weeks. The treatment also inhibited the development of surface IgG+ (sIgG+) B cells and splenomegaly, prominent in aged NZB/W F1 mice. In addition, when untreated NZB/W F1 responding B cells were precultured with normal B cells in vitro for 3 days, they also diminished the autoantibody production to subsequent LPS stimulation. Hence, the present results imply a novel function of normal B cells to ameliorate autoimmune disease in NZB/W F1 mice by correcting their B-cell abnormalities, and indicate that NZB/W F1 and Xid mice possess defects in this regulatory B-cell function.

Interdomain communication regulating ligand binding by PPAR-gamma

Binding to receptors in the cell nucleus is crucial for the action of lipophilic hormones and ligands. PPAR-gamma (for peroxisome proliferator-activated receptor) is a nuclear hormone receptor that mediates adipocyte differentiation and modulates insulin sensitivity, cell proliferation and inflammatory processes. PPAR-gamma ligands have been implicated in the development of atherogenic foam cells and as potential cancer treatments. Transcriptional activity of PPAR-gamma is induced by binding diverse ligands, including natural fatty acid derivatives, antidiabetic thiazolidinediones, and non-steroidal anti-inflammatory drugs. Ligand binding by PPAR-gamma, as well as by the entire nuclear-receptor superfamily, is an independent property of the carboxy-terminal ligand-binding domain (LBD) of the receptor. Here we show that ligand binding by PPAR-gamma is regulated by intramolecular communication between its amino-terminal A/B domain and its carboxy-terminal LBD. Modification of the A/B domain, for example by physiological phosphorylation by MAP kinase, reduces ligand-binding affinity, thus negatively regulating the transcriptional and biological functions of PPAR-gamma. The ability of the A/B domain to regulate ligand binding has important implications for the evaluation and mechanism of action of potentially therapeutic ligands that bind PPAR-gamma and that are likely to extend to other members of the nuclear-receptor superfamily.