bluuebunny/crossref_metadata_2025_split huggingface dataset:
The α6β4 Integrin Can Regulate ErbB-3 Expression: Implications for α6β4 Signaling and Function
Authors: Folgiero Valentina , Bachelder Robin E. , Bon Giulia , Sacchi Ada , Falcioni Rita , Mercurio Arthur M. 
Published: February 2007

Abstract
The integrin α6β4 has been shown to facilitate key functions of carcinoma cells, including their ability to migrate, invade, and evade apoptosis. The mechanism involved seems to be a profound effect of α6β4 on specific signaling pathways, especially the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. An intimate relationship between α6β4 and growth factor receptors may explain this effect of α6β4 on signaling. Previously, we showed that α6β4 and ErbB-2 can function synergistically to activate the PI3K/Akt pathway. Given that ErbB-2 can activate PI3K only when it heterodimerizes with other members of the epidermal growth factor receptor family, these data imply that other receptors cooperate in this process. Here, we report that α6β4 can regulate the expression of ErbB-3 using several different models and that the consequent formation of an ErbB-2/ErbB-3 heterodimer promotes the α6β4-dependent activation of PI3K/Akt and the ability of this integrin to impede apoptosis of carcinoma cells. Our data also support the hypothesis that α6β4 can regulate ErbB-3 expression at the translational level as evidenced by the findings that α6β4 does not increase ErbB-3 mRNA significantly, and that this regulation is both rapamycin sensitive and dependent on eukaryotic translation initiation factor 4E. These findings provide one mechanism to account for the activation of PI3K by α6β4 and they also provide insight into the regulation of ErbB-3 in carcinoma cells. [Cancer Res 2007;67(4):1645–52]
Gene expression analysis of gallium-resistant and gallium-sensitive lymphoma cells reveals a role for metal-responsive transcription factor-1, metallothionein-2A, and zinc transporter-1 in modulating the antineoplastic activity of gallium nitrate
Authors: Yang Meiying , Kroft Steven H. , Chitambar Christopher R. 
Published: February 2007

AbstractSeveral clinical trials have shown gallium nitrate to be an active agent in the treatment of lymphoma. Whereas gallium is known to target cellular iron homeostasis, the basis for lymphoma cell resistance to gallium is not known. Understanding mechanisms of resistance may suggest strategies to enhance the clinical efficacy of gallium. In the present study, we used a focused DNA microarray to compare the expression of genes related to metal metabolism in gallium-resistant and gallium-sensitive lymphoma cell lines developed by us. Gallium-resistant cells were found to display a marked increase in gene expression for metallothionein-2A and the zinc transporter ZnT-1. Cells exposed to gallium nitrate displayed an increase in the binding of metal-responsive transcription factor-1 to metal response element sequences involved in the transcriptional regulation of metallothionein and ZnT-1 genes. Gallium nitrate induced metallothionein-2A and ZnT-1 expression in cells. A role for metallothionein in modulating the antineoplastic activity of gallium was confirmed by showing that the induction of metallothionein expression by zinc provided partial protection against the cytotoxicity of gallium and by showing that the level of endogenous metallothionein in lymphoma cell lines correlated with their sensitivity to gallium nitrate. Immunohistochemical staining of lymphomatous tissues revealed metallothionein protein to be variably expressed in different lymphomas. Our studies show for the first time that gallium acts on pathways related to zinc metabolism and that metal-responsive transcription factor-1 activity and metallothionein expression contribute to the development of gallium drug resistance. Furthermore, the endogenous level of metallothionein in lymphoma may be an important determinant of clinical response to gallium nitrate. [Mol Cancer Ther 2007;6(2):633–43]
Docetaxel-induced apoptosis in melanoma cells is dependent on activation of caspase-2
Authors: Mhaidat Nizar M. , Wang Yufang , Kiejda Kelly A. , Zhang Xu Dong , Hersey Peter 
Published: February 2007

Abstract
Taxanes have a broad spectrum of activity against various human cancers, including melanoma. In this study, we have examined the molecular mechanism of docetaxel-induced apoptosis of human melanoma. We report that docetaxel induced varying degrees of apoptosis in a panel of melanoma cell lines but not in normal fibroblasts. Induction of apoptosis was caspase dependent and associated with changes in mitochondrial membrane potential that could be inhibited by overexpression of Bcl-2. Docetaxel induced changes in Bax that correlated with sensitivity to docetaxel-induced apoptosis. These changes in Bax were not inhibited by overexpression of Bcl-2. Kinetic studies of caspase-2 activation by Western blotting and fluorogenic assays revealed that activation of caspase-2 seemed to be the initiating event. Inhibition of caspase-2 with z-VDVAD-fmk or by small interfering RNA knockdown inhibited changes in Bax and mitochondrial membrane potential and events downstream of mitochondria. Activation of caspase-8 and Bid seemed to be a late event, and docetaxel was able to induce apoptosis in cells deficient in caspase-8 and Bid. p53 did not seem to be involved as a p53 null cell line was sensitive to docetaxel and an inhibitor of p53 did not inhibit apoptosis. Small interfering RNA knockdown of PUMA and Noxa also did not inhibit apoptosis. These results suggest that docetaxel induces apoptosis in melanoma cells by pathways that are dependent on activation of caspase-2, which initiates mitochondrial dependent apoptosis by direct or indirect activation of Bax. [Mol Cancer Ther 2007;6(2):752–61]
Potent arterial antithrombotic effect of direct factor-Xa inhibition with ZK-807834 administered to coronary artery disease patients
Authors: Zafar Urooj , Osende Julio , Shimbo Daichi , Palencia Stella , Crook Julia , Leadley Robert , Fuster Valentin , Chesebro James , Farkouh Michael 
Published: February 2007

SummaryIt was the objective of this study to evaluate the anti-thrombotic potency of direct factor-Xa inhibition with ZK-807834 in stable coronary patients, using an ex-vivo model of arterial thrombus formation. Tissue factor pathway is important in atherothrom-bosis. Direct factor-Xa blockade may more potently reduce thrombosis and prevent coronary events. Badimon Perfusion Chamber 5-minute quantitative studies have shown 40-55% arterial thrombus reduction with abciximab, 23% with Clopidogrel, but none with heparin. Coronary patients (n= 18, 59 ± 9 years, 55% males) were blindly randomized to four groups receiving 24-hour infusion of a low, medium or high dose of direct factor-Xa inhibitor ZK-807834, or placebo. Arterial thrombus formation was measured in Badimon Chamber at baseline, end-of-infusion [Eol], and four hours and eight hours after Eol, and factor-X activity, prothrombin time [PT] ratio and plasma drug levels were measured simultaneously. For the low-, medium- and high-dose ZK-807834 groups, mean percent-reduction in thrombus size from baseline to Eol were 29%, 34% and 68%, respectively (p<0.00l), and at 8-h post Eol were 11%, 19% and 27%, respectively (p<0.01). Mean PT-ratio prolongation showed a strong linear relationship (Pearson’s r=0.93) with ZK-807834 plasma concentration. Mean percent-reduction in factor-X activity from baseline was 13%, 42% and 58%, respectively. Placebo had no effect on thrombus size or factor-X activity. In conclusion, direct factor-Xa inhibition with ZK-807834 markedly reduces ex-vivo arterial thrombus formation and factor-X activity in a dose-dependent manner. Plasma levels of ZK-807834 show a strong linear correlation with PT ratio. This direct factor-Xa inhibitor may reduce the need for additional potent glycoprotein llbllla inhibition.
Platelet activation via PAR4 is involved in the initiation of thrombin generation and in clot elasticity development
Authors: Ramström Sofia , Bjerke Maria , Lindahl Tomas , Vretenbrant Karin 
Published: February 2007

SummaryThrombin is a pivotal enzyme formed in the coagulation cascade and an important and potent platelet activator. The two pro-tease-activated thrombin receptors on human platelets are denoted PARI and PAR4. The physiological relevance of PAR4 is still unclear, as both aggregation and secretion can be accomplished by PARI activation alone. In the present study we have investigated the role of PARs in platelet activation, blood coagulation, clot elasticity and fibrinolysis. Flow cytometry, free oscillation rheometry and thrombin generation measurements were used to analyze blood or platelet-rich plasma from healthy individuals. Maximum PARI activation with the peptide SFLLRN gave fewer fibrinogen-binding platelets with lower mean fluorescent intensity than maximum PAR4 activation with AYPGKF. Inhibition of any of the receptors prolonged clotting times. However, PARI is more important for fibrinolysis; inhibition of this receptor prolonged all the steps in the fibrinolytic process. Clot elasticity decreased significantly when the PAR4 receptor was inhibited. In the thrombin generation measurements, PAR4 inhibition delayed the thrombin generation start and peak, but did not affect the total amount of thrombin generated. PAR I inhibition had no significant impact on thrombin generation. We found that PAR4 is most likely activated by low concentrations of thrombin during the initial phase of thrombin generation and is of importance to the clotting time. Furthermore, we suggest that the PAR4 receptor may have a physiological role in the stabilisation of the coagulum.
Glycoprotein Ibα inhibition and ADP receptor antagonists, but not aspirin, reduce platelet thrombus formation in flowing blood exposed to atherosclerotic plaques
Authors: Penz Sandra , Reininger Armin , Toth Orsolya , Deckmyn Hans , Brandi Richard , Siess Wolfgang 
Published: February 2007

SummaryAnti-platelet drugs are used to prevent intra-arterial thrombus formation after rupture of atherosclerotic plaques. Until now, the inhibitory effect of present and future anti-platelet drugs such as aspirin, ADP receptor P2Y1/P2Y12 antagonists and glycoprotein (GP) Ibα inhibitors on the interaction of platelets with human plaques is not known. To study those effects we obtained human atherosclerotic plaques by surgical endarterectomy. Plaques induced maximal platelet aggregation in hirudinized platelet-rich plasma (PRP) and blood that was effectively inhibited by aspirin, the P2Y1 antagonist MRS2179 and the P2Y12 antagonist AR-C69931 MX, but not by GPIbα blockade with the mAB 6B4. Inhibition of platelet aggregation by MRS2179 was 74 ± 37% and 68 ± 20%, by AR-C69931 MX 94 ± 7% and 80 ± 6%, and by aspirin 88 ± 19% and 64 ± 28%, in PRP and blood, respectively (mean ± SD; n6–12 with plaques from 6 patients). The combination of both ADP receptor antagonists completely inhibited plaque-induced platelet aggregation in hirudinized PRP and blood. Under arterial flow conditions (1,500s-1), blockade of platelet GPIbα– resulted in a strong decrease of plaque-stimulated platelet adhesion/aggregate formation of 77 ± 5% (mean ± SD; n=4). Furthermore, MRS2I79, AR-C6993IMX and their combination reduced plaque-dependent platelet aggregate formation by 35 ± 14%, 32 ± 13% and 58 ± 12% (mean ± SD; n=5), respectively. Aspirin was without significant effect. In conclusion, a GPIbα-blocking antibody, as well as P2Y1 and P2Y12 receptor antagonists, alone or in combination, reduce in contrast to aspirin human plaque-induced platelet thrombus formation under arterial flow. Although these new anti-platelet agents inhibit platelet thrombus formation after plaque rupture, more efficient platelet blockers are required.
Interaction of an annexin V homodimer (Diannexin) with phosphatidylserine on cell surfaces and consequent antithrombotic activity
Authors: Larkin Sandra , Emeis Jef , Allison Anthony , Kuypers Frans 
Published: February 2007

SummaryAnnexin V(AV), a protein with anticoagulant activity, exerts antithrombotic activity by binding to phosphatidylserine (PS), inhibiting activation of serine proteases important in blood coagulation. The potential use of this protein as an anticoagulant is limited as it rapidly passes from the blood into the kidneys due to its relatively small size (36 kDa). We used recombinant DNA technology to produce a homodimer of human AV (DAV, 73 kDa), which exceeds the renal filtration threshold, and has a 6.5-hour half-life in the rat circulation. Human red blood cells with externalized PS were used to show that DAV had a higher affinity for PS-exposing cells than AV. DAV labeling sensitively identifies PS-exposing cells, was found to be a potent inhibitor of the activity of the prothombinase complexes and inhibits the ability of secretory phospholipase A2 to hydrolyze phospholipids of PS-exposing cells, reducing the formation of mediators of blood coagulation and reperfusion injury. DAV exerts dose-dependent antithrombotic activity in ratveins. This combination of activities suggests that DAV is a valuable probe to measure PS exposure and may be efficacious as a novel drug in a wide range of clinical situations.
Signal transduction induced in endothelial cells by growth factor receptors involved in angiogenesis
Authors: Schweighofer Bernhard , Hofer Erhard 
Published: February 2007

SummaryNew vessel formation during development and in the adult is triggered by concerted signals of largely endothelial-specific receptors for ligands of the VEGF, angiopoietin and ephrin families. The signals and genes induced by these receptors operate in the context of additional signals transduced by non-endothelial specific growth factor receptors, inflammatory cytokine receptors as well as adhesion molecules. We summarize here available data on characteristic signaling of the VEGF receptor-2 and the current state of knowledge regarding the additional different receptor tyrosine kinases of the VEGF, Tie and Ephrin receptor families. Furthermore, the potential cross-talk with signals induced by other growth factors and inflammatory cytokines as well as the modulation by VE-cadherin is discussed.
Ubiquitylation within signaling pathways in- and outside of inflammation
Authors: Hochrainer Karin , Lipp Joachim 
Published: February 2007

SummaryUbiquitin is a highly conserved 76-amino-acid peptide that becomes covalently attached to lysine residues of target proteins. Since ubiquitin itself contains seven lysine residues, ubiquitin molecules can generate different types of polyubiquitin chains. Lys48-linked polyubiquitylation is well-known as posttrans-lational tag for targeting proteins for degradation by the 26S proteasome. Recent studies have revealed several new functions of ubiquitin, e.g. activation of protein kinases, control of gene transcription, DNA repair and replication, intracellular trafficking and virus budding. These functions are mainly mediated by Lys63 polyubiquitin chains or attachment of a single ubiquitin molecule to one or several lysine residues within the target protein. Importantly, protein ubiquitylation exhibits inducibility, reversibilty and recognition by specialized ubiquitin-binding domains, features similar to protein phosphorylation. In this review we comprehensively describe regulations of protein ubiquitylation and their impact on distinct signaling pathways.
Fluorescent proteins and fluorescence resonance energy transfer (FRET) as tools in signaling research
Authors: Birbach Andreas , Schmid Johannes 
Published: February 2007

SummaryThe advent of fluorescent proteins has revolutionized signaling research, shifting focus from biochemical assays to analysis of live cells, organized tissues and even entire organisms. Modern applications of fluorescent proteins go beyond their use as specific markers of cells or tissues, allowing the researcher to visualize intracellular translocations as well as biochemical reactions. In this mini-review, we summarize the properties of a variety of fluorescent proteins, their detection using fluorescence microscopy and flow analysis, as well as their basic and more advanced applications, including fluorescence resonance energy transfer (FRET) to study signaling dynamics.
Resolution of inflammation: Intracellular feedback loops in the endothelium
Authors: Winsauer Gabriele , de Martin Rainer 
Published: February 2007

SummaryTimely termination of the inflammatory reaction is equally important as its elicitation, since a persistent or exaggerated response may lead to detrimental effects in the affected tissues and organs. Therefore, and in accordance with the complex and highly coordinated activation phase, negative regulatory mechanisms have evolved which function on multiple levels to ensure the appropriate termination of the inflammatory response. This review will focus on the mechanisms that are operative in endothelial cells to shut down the activity of specific signaling pathways and transcription factors that have been activated in response to pro-inflammatory mediators, and provide evidence that the stage for resolution is set already early in the activation phase of the inflammatory response. The elucidation of these feedback mechanisms is of importance for the understanding of acute versus chronic inflammation, and for novel strategies for therapeutic intervention.
Inflammatory profile of oxidized phospholipids
Authors: Bochkov Valery 
Published: February 2007

SummaryLipid oxidation products and in particular oxidized phospholipids (OxPL) are increasingly recognized as inducers of chronic inflammation characteristic of atherosclerosis. OxPL stimulate production of chemokines and adhesion of monocytes to endothelial cells. However, accumulating data suggest that, in addition to the proatherogenic and proinflammatory effects, OxPL can stimulate antiinflammatory and tissue-protective mechanisms. Thus, depending on the biological situation, OxPL can either stimulate or inhibit inflammation. In this review, the inflammatory properties of OxPL are discussed together with the underlying receptor, signalling and transcriptional mechanisms.
Plasma tissue factor antigen in localized prostate cancer: Distribution, clinical significance and correlation with haemostatic activation markers
Authors: Chun Felix , Amirkhosravi Ali , Friedrich Martin , Leuenroth Sven , Eifrig Barbara , Bokemeyer Carsten , Francis John , Langer Florian 
Published: February 2007

SummaryTissue factor (TF) is involved in cancer growth and metastasis, and haemostatic abnormalities are found in most patients with advanced malignancies, including prostate cancer (PC). Because anti-haemostatic agents are increasingly screened for their potential to prolong survival in tumor patients, a detailed characterization of haemostatic markers in selected cancer subtypes and clinical stages is warranted. In this study, we measured preoperative plasma TF antigen in a large cohort of patients with localized PC and correlated its levels with markers of coagulation and platelet activation, prostate-specific antigen (PSA), and his-topathological findings to explore its potential as a prognostic marker in this tumor entity. Out of 140 patients, 19% and 23% had plasma TF antigen levels of <40 pg/ml (low-TF) and >200 pg/ ml (high-TF), respectively, which was substantially higher than in 42 healthy male controls. Patients also had low-grade systemic coagulation activation as evidenced by elevated D-dimer, FI +2, and PAP plasma levels. Furthermore, similar to sP-selectin and sCD40L antigen, flow cytometric analysis of platelet-derived microparticles in plasma revealed significantly increased numbers in high-TF as compared to low-TF patients and controls. Whereas elevated D-dimer was associated with larger and less differentiated tumors, preoperative plasmaTF antigen levels (median [IQR]) were higher in patients with (161 pg/ml [100-236]) than in those without recurrent PC (105 pg/ml [52-182]), as indicated by a serum PSA of >0.1 ng/ml during ambulatory follow-up. In patients with localized PC, preoperative plasma TF antigen levels correlate with platelet activation in vivo and may indicate an increased risk for recurrent disease.
Prevention by NCX 4016, a nitric oxide-donating aspirin, but not by aspirin, of the acute endothelial dysfunction induced by exercise in patients with intermittent claudication
Authors: Migliacci Rino , Procacci Alessandra , De Monte Paola , Bonizzoni Erminio , Gresele Paolo 
Published: February 2007

SummaryIschemia/reperfusion damage evokes systemic inflammation and endothelial dysfunction in patients with intermittent claudication. We compared the effects of aspirin with those of a nitric oxide-donating aspirin in preventing the acute, systemic endothelial dysfunction provoked by exercise-induced ischemia of the lower limbs in patients with intermittent claudication. In a prospective, randomized, single-blind, parallel-groups trial among 44 patients with intermittent claudication we compared four weeks of aspirin (100 mg o.d.) with NCX 4016 (800 mg b.i.d.). Primary end point was the exercise-induced changes in brachial flow-mediated vasodilation (FMD) at day 28; secondary end points were effort-induced changes of markers of neutrophil (plasma elastase) and endothelial (soluble VCAM-1) activation. Baseline FMD was comparable in the two groups, both on day I (pre-treatment: aspirin = 3.1 ± 0.5%, nitroaspirin = 3.9 ± 0.7%, p=NS), and on day 28 (aspirin = 3.4 ± 0.7%, NCX 4016 = 3.2 ± 0.6%, p=NS). Maximal treadmill exercise induced an acute worsening of FMD in both groups at baseline (aspirin = –1.15%, nitroaspirin = –1.76%); after four weeks treatment, the impairment of FMD induced by exercise was still present in the aspirin-treated group (- 1.46%) while it was abolished in the NCX 4016-treated group (+ 0.79%, p= 0.038 vs. aspirin). Similarly, exercise induced an increase of plasma elastase and of sVCAM-l which were not affected by aspirin while they were suppressed by NCX 4016. Maximal treadmill exercise induces a systemic arterial endothelial dysfunction in patients with intermittent claudication. A nitric oxide-donating aspirin, but not aspirin, prevents effort-induced endothelial dysfunction.