Biomedical subjects

Bodo Levkau

Publications and source records attributed to Bodo Levkau.

At least 19 recordsLinked to original sources

PubMed2007

Roles of cyclooxygenase-2 and phosphorylated Akt (Thr308) in cardiac hypertrophy regression mediated by left-ventricular unloading.

OBJECTIVES: Cyclooxygenase-2 is associated with cardiac hypertrophy during chronic heart failure and is regulated through the PI3K/Akt pathway. Cyclooxygenase-2-induced cell growth through Akt phosphorylation was demonstrated in vitro. In chronic heart failure, left ventricular assist devices lead to hypertrophy regression and molecular changes. Therefore, the expression of cyclooxygenase-2, phosphorylated Akt (p-Akt), and p-Erk 1/2, as well as cardiac hypertrophy before and after left ventricular assist device insertion, was investigated. METHODS: In myocardial tissue before and after left ventricular assist device insertion, the expression of cyclooxygenase-2, p-Akt (Thr308), p-Akt (Ser473), and p-Erk 1/2 was demonstrated by immunohistochemistry and quantified by morphometry. Colocalization of cyclooxygenase-2 and p-Akt (Thr308) was investigated by immuno-doublestaining. RESULTS: A significant decrease of cyclooxygenase-2, p-Akt (Thr308), p-Akt (Ser473), and p-Erk 1/2 protein expression and hypertrophy regression was observed after left ventricular assist device insertion. A significant correlation between cyclooxygenase-2 and p-Akt (Thr308) expression, as well as between cyclooxygenase-2 expression and cardiomyocyte diameter, was observed before, but not after, left ventricular assist device insertion. Only cyclooxygenase-2-positive cardiomyocytes showed significant hypertrophy regression on unloading. Sarcoplasmic colocalization of cyclooxygenase-2 and p-Akt (Thr308) is present before left ventricular assist device insertion and is decreased after unloading, whereas the normal myocardium is completely devoid of it. CONCLUSIONS: Left ventricular assist device treatment is associated with a significant decrease of cyclooxygenase-2, p-Akt (Thr308), p-Akt (Ser473), and p-Erk 1/2, and cardiac hypertrophy regression of cyclooxygenase-2-positive cardiomyocytes. The significant correlation and colocalization in cardiomyocytes of cyclooxygenase-2 and p-Akt (Thr308) before left ventricular assist device insertion suggests a cross-talk between the 2 molecules in the progression of cardiac hypertrophy, which is reversibly regulated by the left ventricular assist device.

Adolescent↗

PubMed2006

Sphingosine-1-phosphate stimulates the functional capacity of progenitor cells by activation of the CXCR4-dependent signaling pathway via the S1P3 receptor.

OBJECTIVE: Sphingosine-1-phosphate (S1P) is a bioactive lipid, which influences migration and proliferation of endothelial cells through activation of S1P receptors and has been shown to support SDF-1 induced migration and bone marrow homing of CD34+ progenitors. METHODS AND RESULTS: Here, we show that incubation of patient-derived endothelial progenitor cells (EPCs) with S1P or its synthetic analog FTY720 improved blood flow recovery in ischemic hind limbs. Likewise, recovery of blood flow was dramatically reduced after induction of hindlimb ischemia in mice deficient for the S1P receptor 3 (S1P3). S1P3-/- bone marrow-derived mononuclear cells (BMCs) failed to augment neovascularization after hind limb ischemia. Of note, treatment of BMCs derived from S1P3-/- mice with S1P did not rescue blood flow recovery. Mechanistically, S1P and FTY720 induced phosphorylation of CXCR4, activated the Src kinase, and stimulated phosphorylation of JAK2. The contribution of CXCR4 for S1P-mediated effects was further supported by the findings that S1P preincubation failed to stimulate invasion capacity and in vivo blood flow recovery of BMCs from CXCR4+/- mice. The activation of CXCR4 was dependent on the Src kinase family as demonstrated by preincubation with the Src inhibitor PP2. The activation of the CXCR4 signaling by S1P is mediated via the S1P3 receptor, since S1P-induced Src phosphorylation was abrogated in EPC from S1P3-/- mice. CONCLUSIONS: S1P agonists might serve as sensitizers of CXCR4-mediated signaling and may be applied in clinical progenitor cell therapy to improve EPC or BMC function in patients with coronary artery disease.

Animals↗

PubMed2006

The sphingosine-1-phosphate analogue FTY720 reduces atherosclerosis in apolipoprotein E-deficient mice.

OBJECTIVE: The sphingosine-1-phosphate (S1P) analogue FTY720 is a potent immunosuppressive agent currently in Phase III clinical trials for kidney transplantation. FTY720 traps lymphocytes in secondary lymphoid organs thereby preventing their migration to inflammatory sites. Previously, we have identified FTY720 as a potent activator of eNOS. As both inhibition of immune responses and stimulation of eNOS may attenuate atherosclerosis, we administered FTY720 to apolipoprotein E-/- mice fed a high-cholesterol diet. METHODS AND RESULTS: FTY720 dramatically reduced atherosclerotic lesion volume (62.5%), macrophage (41.8%), and collagen content (63.5%) after 20 weeks of high-cholesterol diet. In isolated aortic segments and cultured vascular smooth muscle cell, FTY720 potently inhibited thrombin-induced release of monocyte chemoattractant protein-1. This effect was mediated by the S1P3 sphingolipid receptor as FTY720 had no effect on thrombin-induced monocyte chemoattractant protein-1 release in S1P3-/- mice. In contrast to S1P receptors on lymphocytes, FTY720 did not desensitize vascular S1P receptors as arteries from FTY720-treated mice retained their vasodilator response to FTY720-phosphate. CONCLUSIONS: We suggest that FTY720 inhibits atherosclerosis by suppressing the machinery involved in monocyte/macrophage emigration to atherosclerotic lesions. As vascular S1P receptors remained functional under FTY720 treatment, S1P agonists that selectively target the vasculature and not the immune system may be promising new drugs against atherosclerosis.

Animals↗

PubMed2006

5-pyrrolidinylsulfonyl isatins as a potential tool for the molecular imaging of caspases in apoptosis.

Caspases are the unique enzymes responsible for the execution of the cell death program and may represent an exclusive target for the specific molecular imaging of apoptosis in vivo. 5-Pyrrolidinylsulfonyl isatins represent potent nonpeptidyl caspase inhibitors that may be suitable for the development of caspase binding radioligands (CBRs). (S)-5-[1-(2-Methoxymethylpyrrolidinyl)sulfonyl]isatin (7) served as a lead compound for modification of its N-1-position. Corresponding pairs of N-1-substituted 2-methoxymethyl- and 2-phenoxymethylpyrrolidinyl derivatives were examined in vitro by biochemical caspase inhibition assays. All target compounds possess high in vitro caspase inhibition potencies in the nanomolar to subnanomolar range for caspase-3 (Ki=0.2-56.1 nM). As shown for compound (S)-1-(4-(2-fluoroethoxy)benzyl)-5-[1-(2-methoxymethylpyrrolidinyl)sulfonyl]isatin (35), the class of N-1-substituted 5-pyrrolidinylsulfonyl isatins competitively inhibits caspase-3. All caspase inhibitors show selectivity for the effector caspases-3 and -7 in vitro. The 2-methoxymethylpyrrolidinyl versions of the isatins appear to possess superior caspase inhibition potencies in cellular apoptosis inhibition assays compared with the 2-phenoxymethylpyrrolidinyl inhibitors.

Apoptosis↗

PubMed2006

Age- and training-dependent development of arrhythmogenic right ventricular cardiomyopathy in heterozygous plakoglobin-deficient mice.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes sudden death and right ventricular heart failure in the young. Clinical data suggest that competitive sports may provoke ARVC in susceptible persons. Genetically, loss-of-function mutations in desmosomal proteins (plakophilin, desmoplakin, or plakoglobin) have been associated with ARVC. To test the hypothesis that reduced desmosomal protein expression causes ARVC, we studied the cardiac effects of heterozygous plakoglobin deficiency in mice. METHODS AND RESULTS: Ten-month-old heterozygous plakoglobin-deficient mice (plakoglobin+/-) had increased right ventricular volume, reduced right ventricular function, and spontaneous ventricular ectopy (all P<0.05). Left ventricular size and function were not altered. Isolated, perfused plakoglobin+/- hearts had spontaneous ventricular tachycardia of right ventricular origin and prolonged right ventricular conduction times compared with wild-type hearts. Endurance training accelerated the development of right ventricular dysfunction and arrhythmias in plakoglobin+/- mice. Histology and electron microscopy did not identify right ventricular abnormalities in affected animals. CONCLUSIONS: Heterozygous plakoglobin deficiency provokes ARVC. Manifestation of the phenotype is accelerated by endurance training. This suggests a functional role for plakoglobin and training in the development of ARVC.

Aging↗

PubMed2006

High-density lipoproteins and their constituent, sphingosine-1-phosphate, directly protect the heart against ischemia/reperfusion injury in vivo via the S1P3 lysophospholipid receptor.

BACKGROUND: All treatments of acute myocardial infarction are aimed at rapid revascularization of the occluded vessel; however, no clinical strategies are currently available to protect the heart from ischemia/reperfusion injury after restitution of blood flow. We hypothesized that some of the cholesterol transport-independent biological properties of high-density lipoprotein (HDL) implied in atheroprotection may also be beneficial in settings of acute myocardial reperfusion injury. METHODS AND RESULTS: In an in vivo mouse model of myocardial ischemia/reperfusion, we observed that HDL and its sphingolipid component, sphingosine-1-phosphate (S1P), dramatically attenuated infarction size by approximately 20% and 40%, respectively. The underlying mechanism was an inhibition of inflammatory neutrophil recruitment and cardiomyocyte apoptosis in the infarcted area. In vitro, HDL and S1P potently suppressed leukocyte adhesion to activated endothelium under flow and protected rat neonatal cardiomyocytes against apoptosis. In vivo, HDL- and S1P-mediated cardioprotection was dependent on nitric oxide (NO) and the S1P3 lysophospholipid receptor, because it was abolished by pharmacological NO synthase inhibition and was completely absent in S1P3-deficient mice. CONCLUSIONS: Our data demonstrate that HDL and its constituent, S1P, acutely protect the heart against ischemia/reperfusion injury in vivo via an S1P3-mediated and NO-dependent pathway. A rapid therapeutic elevation of S1P-containing HDL plasma levels may be beneficial in patients at high risk of acute myocardial ischemia.

Animals↗

PubMed2006

Integrin-mediated transcriptional activation of inhibitor of apoptosis proteins protects smooth muscle cells against apoptosis induced by degraded collagen.

Apoptosis of smooth muscle cells (SMC) and degradation of the extracellular matrix (ECM) have both been implicated in atherosclerotic plaque rupture. We have previously reported that degraded type I collagen fragments induce a rapid but transient apoptotic burst initiated by calpains in SMC. The aim of the current study was to identify the pathway responsible for consecutive SMC survival. We show that exposure of SMC to collagen fragments resulted in a sustained activation of nuclear factor (NF)-kappaB via phosphorylation and degradation of IkappaBalpha. Its prevention through retroviral expression of superrepressor IkappaBalpha or proteasome inhibition potently induced apoptosis. In the presence of blocking antibodies to alpha(v)beta(3) integrin and RGD peptides, collagen fragments no longer activated NF-kappaB and apoptosis was enhanced. The mechanism by which NF-kappaB was protecting SMC against collagen fragment-induced apoptosis was a transcriptional activation of several endogenous caspase inhibitors of the inhibitor of apoptosis protein (IAP) family as: (1) the expression of xIAP, c-IAP2, and survivin was potently induced by collagen fragments; (2) IAP expression was abrogated by superrepressor IkappaBalpha; and (3) knockdown of each of the 3 IAPs by small interfering RNA (siRNA) resulted in enhanced apoptosis after collagen fragment treatment. Our data suggest that SMC exposed to degraded collagen are protected against apoptosis by a mechanism involving alpha(v)beta(3)-dependent NF-kappaB activation with consequent activation of IAPs. This may constitute a novel antiapoptotic pathway ensuring SMC survival in settings of enhanced ECM degradation such as cell migration, vascular remodeling, and atherosclerotic plaque rupture.

Apoptosis↗

PubMed2006

Stress associated proteins metallothionein, HO-1 and HSP 70 in human zero-hour biopsies of transplanted kidneys.

Light microscopic alterations reflecting both previous and preservation-induced changes in the donor organ are usually not very distinctive. The ischemia/reperfusion-associated injury depends primarily on the conditions of donor organ preservation. The present study examined human kidney biopsies with special attention paid to the molecular mechanisms of preservation-induced injury preceding reperfusion. Stress-associated proteins hemeoxygenase-1 (HO-1), heat shock protein 70 (HSP 70), and metallothionein (MT) were studied in human zero-hour biopsies of transplanted kidneys prior to reperfusion in 29 patients. Protein expression was evaluated by semiquantitative immunohistochemistry and Western blotting for HO-1 and HSP 70. These findings were correlated with terminal deoxynucleotidyltransferase-mediated 2'-deoxyuridine 5'-triphosphate-digoxigenin nick end labeling (TUNEL) staining and follow up. Compared to controls, MT and HSP 70 expression was significantly higher at zero hour. In contrast, HO-1 and the number of TUNEL-positive cells were not elevated. MT and HO-1 immunoexpression were inversely associated with graft function, and hence, were of prognostic relevance. MT and HSP 70 were sensitive to the duration of cold ischemia. MT and HO-1 are suitable indicators for tissue injury during ischemia and may serve as new predictive markers that need to be validated in further independent studies.

Adult↗

PubMed2006

The proteasome is required for rapid initiation of death receptor-induced apoptosis.

Due to their tremendous apoptosis-inducing potential, proteasomal inhibitors (PIs) have recently entered clinical trials. Here we show, however, that various PIs rescued proliferating tumor cells from death receptor-induced apoptosis. This protection correlated with the stabilization of X-linked IAP (XIAP) and c-FLIP and the inhibition of caspase activation. Together with the observation that PIs could not protect cells expressing XIAP or c-FLIP short interfering RNAs (siRNAs) from death receptor-induced apoptosis, our results demonstrate that PIs mediate their protective effect via the stabilization of these antiapoptotic proteins. Furthermore, we show that once these proteins were eliminated, either by long-term treatment with death receptor ligands or by siRNA-mediated suppression, active caspases accumulated to an even larger extent in the presence of PIs. Together, our data support a biphasic role for the proteasome in apoptosis, as they show that its constitutive activity is crucial for the rapid initiation of the death program by eliminating antiapoptotic proteins, whereas at later stages, the proteasome acts in an antiapoptotic manner due to the proteolysis of caspases. Thus, for a successful PI-based tumor therapy, it is crucial to carefully evaluate basal proteasomal activity and the status of antiapoptotic proteins, as their PI-mediated prolonged stability might even cause adverse effects, leading to the survival of a tumor.

Apoptosis↗

PubMed2005

Synthesis, in vitro pharmacology and biodistribution studies of new PD 156707-derived ET(A) receptor radioligands.

It is assumed that the regulation of cardiac endothelin (ET) receptor density is abnormal in heart diseases. From that perspective, an ET receptor radioligand is needed to assess ET receptor density in vivo. The nonpeptidyl ET(A) receptor antagonist PD 169390 was labelled with radioiodine to give a putative radioligand for SPECT. Labelling with [125I]iodide and [123I]iodide was accomplished with good to excellent radiochemical yields. The affinities of the nonradioactive reference and those of selected precursor compounds for ET(A) receptors were determined, using [125I]iodine labelled endothelin-1 with mouse ventricular membranes. All employed substances exhibited potent in vitro pharmacological characteristics with Ki values comparable to that of the lead compound PD 156707. Biodistribution studies and scintigraphic imaging experiments in mice, however, showed no significant uptake of the [123I] derivative in the heart.

Animals↗

PubMed2005

Degraded collagen induces calpain-mediated apoptosis and destruction of the X-chromosome-linked inhibitor of apoptosis (xIAP) in human vascular smooth muscle cells.

OBJECTIVE: The extracellular matrix (ECM) of the atherosclerotic lesion is a crucial determinant of its stability, while its degradation by matrix metalloproteinases (MMPs) has been implied in plaque rupture. As accumulation of both MMP-derived collagen fragments and apoptotic smooth muscle cells (SMC) is observed at sites of plaque rupture, we tested the effect of polymerized and degraded type I collagen on the susceptibility of SMC to apoptosis. METHODS: Human SMC were cultured on monomeric or polymerized collagen, and collagen gels were degraded by collagenase. Apoptosis was evaluated using antibodies to active caspases and their substrates. Calpain and caspase activity were measured using fluorogenic substrates. RESULTS: Culture of SMC on polymerized collagen led to increased apoptosis compared to culture on monomeric collagen. In addition, we observed a distinct proteolytic degradation of the endogenous caspase inhibitor X-chromosome-linked inhibitor of apoptosis (xIAP). As MMP-1 was strongly activated in SMC on polymerized collagen, we examined the effect of degraded collagen fragments on xIAP cleavage and apoptosis. Degraded collagen induced rapid proteolytic processing of xIAP identical to that on polymerized collagen. We identified calpains as the proteolytic enzymes responsible for xIAP processing as: i) they were rapidly activated by degraded collagen; ii) recombinant calpain II processed xIAP in an identical manner, and iii) inhibition of calpains by BAPTA or calpeptin abrogated xIAP degradation in intact cells. The functional consequence of xIAP processing by calpains was a loss of its caspase-inhibitory potential. Calpain activation distinctly preceded caspase activation, and inhibition of calpains suppressed apoptosis. CONCLUSIONS: Collagen fragments proteolytically released from the ECM by MMPs may propagate apoptosis of SMC by calpain-mediated inactivation of anti-apoptotic proteins such as xIAP. This may be a novel mechanism of SMC apoptosis in biological settings of enhanced collagen degradation such as vascular remodeling, neointima formation, and atherosclerotic plaque rupture.

Apoptosis↗

PubMed2005

Reverse remodeling following insertion of left ventricular assist devices (LVAD): a review of the morphological and molecular changes.

Left ventricular assist devices (LVAD) are used to "bridge" patients with end-stage heart failure until transplantation of a donor heart can be performed ("bridge to transplantation"). However, in a subset of patients, support by LVAD sporadically results in improved cardiac function, with heart transplantation no longer necessary even after removal of the LVAD ("bridge to recovery"). Also, LVAD appears to be an optional treatment alternative to heart transplantation in patients with contraindications for organ replacement ("destination therapy"). The processes resulting in these effects have descriptively been termed "reverse remodeling". Although the molecular mechanisms are incompletely understood at present, there are several aspects of the reverse remodeling process that have been identified in the past. Alterations of many molecular pathways are involved in the development of chronic heart failure. Some of these appear to be reversible and have been shown to be regulated by LVAD treatment. LVAD lead to lowered cardiac pressure and volume overload in the myocardium followed by decreased ventricular wall tension, reduced cardiomyocyte hypertrophy, improved coronary perfusion and decreased chronic ischemia. Improved coronary flow and myocardial perfusion as well as decreased ventricular wall tension may possibly alter the molecular systems involved in the development of chronic cardiac insufficiency. Aside from describing the morphological changes, this review focuses on the roles of signal transduction, transcriptional regulation, apoptosis, stress proteins, matrix remodeling, and neurohormonal signaling in the failing human heart before and after mechanical circulatory support.

Adrenergic beta-Agonists↗

PubMed2005

C-5-disubstituted barbiturates as potential molecular probes for noninvasive matrix metalloproteinase imaging.

Studies have demonstrated a positive correlation between inflammation, metastasis, or atherosclerosis and the unbalanced or culminated expression of matrix metalloproteinases (MMPs). The molecular imaging of locally upregulated MMP activity in vivo is a clinical challenge. Actually, radioligands based on nonpeptidyl MMP inhibitors (MMPIs) are currently in development as putative radiopharmaceutical agents for the noninvasive in vivo assessment of activated MMPs. Nonpeptidyl MMPIs bind to the zinc active site of the activated enzyme via mono- (e.g. carboxylate) or bidentate (e.g. hydroxamate) complexation thereby exhibiting a broad-spectrum MMP binding potency. Thus, these mentioned endopeptidase inhibitors should be useable lead compounds for the redevelopment as diagnostic MMPI radiotracers. Recently, the non-hydroxamate C-5-disubstituted pyrimidine-2,4,6-triones were disclosed as subgroup-selective MMP inhibitors. We here describe a set of fine-tuned barbiturates as a new class of MMPI radiotracers for the noninvasive in vivo visualization of activated MMPs using scintigraphic techniques such as SPECT or PET.

Barbiturates↗

PubMed2005

Lack of myoglobin causes a switch in cardiac substrate selection.

Myoglobin is an important intracellular O2 binding hemoprotein in heart and skeletal muscle. Surprisingly, disruption of myoglobin in mice (myo-/-) resulted in no obvious phenotype and normal cardiac function was suggested to be mediated by structural alterations that tend to steepen the oxygen pressure gradient from capillary to mitochondria. Here we report that lack of myoglobin causes a biochemical shift in cardiac substrate utilization from fatty acid to glucose oxidation. Proteome and gene expression analysis uncovered key enzymes of mitochondrial beta-oxidation as well as the nuclear receptor PPAR to be downregulated in myoglobin-deficient hearts. Using FDG-PET we showed a substantially increased in vivo cardiac uptake of glucose in myo-/- mice (6.7+/-2.3 versus 0.8+/-0.5% of injected dose in wild-type, n=5, P<0.001), which was associated with an upregulation of the glucose transporter GLUT4. The metabolic switch was confirmed by 13C NMR spetroscopic isotopomer studies of isolated hearts which revealed that [1,6-13C2]glucose utilization was increased in myo-/- hearts (38+/-8% versus 22+/-5% in wild-type, n=6, P<0.05), and concomitantly, [U-13C16]palmitate utilization was decreased in the myoglobin-deficient group (42+/-6% versus 63+/-11% in wild-type, n=6, P<0.05). Because of the O2-sparing effect of glucose utilization, the observed shift in substrate metabolism benefits energy homoeostasis and therefore represents a molecular adaptation process allowing to compensate for lack of the cytosolic oxygen carrier myoglobin. Furthermore, our data suggest that an altered myoglobin level itself may be a critical determinant for substrate selection in the heart. The full text of this article is available online at http://circres.ahajournals.org.

Animals↗

PubMed2005

Immunomodulator FTY720 Induces eNOS-dependent arterial vasodilatation via the lysophospholipid receptor S1P3.

The novel immunomodulator FTY720 is effective in experimental models of transplantation and autoimmunity, and is currently undergoing Phase III clinical trials for prevention of kidney graft rejection. FTY720 is a structural analogue of sphingosine-1-phosphate (S1P) and activates several of the S1P receptors. We show that FTY720 induces endothelium-dependent arterial vasodilation in phenylephrine precontracted mouse aortae. Vasodilation did not occur in thoracic aortic rings from eNOS-deficient mice, implicating and effect dependent of activation of the eNOS/NO pathway. Accordingly, FTY720 induced NO release, Akt-dependent eNOS phosphorylation and activation in human endothelial cells. For biological efficacy, FTY720 required endogenous phosphorylation, since addition of the sphingosine kinase antagonist N',N-dimethylsphingosine (DMS) prevented activation of eNOS in vitro and inhibited vasodilation in isolated arteries. The endothelial phosphorylation of FTY720 was extremely rapid with almost complete conversion after 10 minutes as determined by mass spectrometry. Finally, we identified the lysophospholipid receptor S1P3 as the S1P receptor responsible for arterial vasodilation by FTY720, as the effect was completely abolished in arteries from S1P3-deficient mice. In summary, we have identified FTY720 as the first immunomodulator for prevention of organ graft rejection in clinical development that, in addition, positively affects the endothelium by stimulating NO production, and thus potentially displaying beneficial effects on transplant survival beyond classical T cell immunosuppression.

Cells, Cultured↗

PubMed2005

High expression of focal adhesion kinase (p125FAK) in node-negative breast cancer is related to overexpression of HER-2/neu and activated Akt kinase but does not predict outcome.

INTRODUCTION: Focal adhesion kinase (FAK) regulates multiple cellular processes including growth, differentiation, adhesion, motility and apoptosis. In breast carcinoma, FAK overexpression has been linked to cancer progression but the prognostic relevance remains unknown. In particular, with regard to lymph node-negative breast cancer it is important to identify high-risk patients who would benefit from further adjuvant therapy. METHODS: We analyzed 162 node-negative breast cancer cases to determine the prognostic relevance of FAK expression, and we investigated the relationship of FAK with major associated signaling pathways (HER2, Src, Akt and extracellular regulated kinases) by immunohistochemistry and western blot analysis. RESULTS: Elevated FAK expression did not predict patient outcome, in contrast to tumor grading (P = 0.005), Akt activation (P = 0.0383) and estrogen receptor status (P = 0.0033). Significant positive correlations were observed between elevated FAK expression and HER2 overexpression (P = 0.001), as well as phospho-Src Tyr-215 (P = 0.021) and phospho-Akt (P < 0.001), but not with phospho-ERK1/2 (P = 0.108). Western blot analysis showed a significant correlation of FAK Tyr-861 activation and HER2 overexpression (P = 0.01). CONCLUSIONS: Immunohistochemical detection of FAK expression is of no prognostic significance in node-negative breast cancer but provides evidence that HER2 is involved in tumor malignancy and metastatic ability of breast cancer through a novel signaling pathway participating FAK and Src.

Blotting, Western↗

PubMed2005

[Scintigraphic molecular imaging].

Modern medicine is currently focusing its basic and clinical research towards "molecular medicine". This trend, together with the decoding of the human genome and the resulting design and use of transgenic mouse models of human diseases, demands that innovative imaging approaches are developed for man and mice. Non-invasive imaging modalities capable of quantifying molecular processes in vivo (collectively defined as "molecular imaging" techniques) are extremely interesting in this respect. This review focuses on the clinical and experimental scintigraphic molecular-imaging modalities SPECT and PET, and summarizes their actual and future impact in medicine.

Animals↗

PubMed2005

Monitoring left ventricular dilation in mice with PET.

UNLABELLED: Molecular imaging by small-animal PET is an important noninvasive means to phenotype transgenic mouse models in vivo. When investigating pathologies of the left ventricular (LV) myocardium, the serial assessment of LV volumes is important. By this, the presence of LV dilation as a sign of developing heart failure can be detected. Whereas PET is usually used to derive biochemical and molecular information, functional parameters such as ventricular volumes are generally measured using echocardiography or MRI. In this study, a novel method to monitor LV dilation in mice with PET is presented and evaluated using cardiac MRI. METHODS: A semiautomatic 3-dimensional algorithm was used to delineate the LV myocardial wall on static PET images depicting myocardial glucose metabolism ((18)F-FDG PET) for 20 mice: 10 wild-type and 10 genetically modified littermates designed to develop a dilative cardiomyopathy phenotype (cardiomyocyte-specific knockout of survivin). The volume enclosed by the 3-dimensional midmyocardial contour was calculated as a measure for LV volume for each mouse. Data were compared with ventricular volumes measured by MRI in the same animals. RESULTS: LV volumes obtained by PET and MRI correlated well (R = 0.89) for hearts with small and large left ventricles. In accordance with the hypothesis, the LV volumes were increased significantly for transgenic mice examined at an older age compared with those examined at a younger age (MRI: 160.5 +/- 25.7 microL vs. 114.7 +/- 15.2 microL [P = 0.012]; PET: 129.3 +/- 15.3 microL vs. 73.8 +/- 15.0 microL [P < 0.001], all values shown as mean +/- SD; for MRI, mean of end-diastolic and end-systolic volumes are given), whereas they did not for their wild-type littermates (MRI: 106.2 +/- 12.3 microL vs. 94.7 +/- 14.6 microL [P = 0.214]; PET: 82.6 +/- 20.9 microL vs. 65.0 +/- 16.9 microL [P = 0.185]). CONCLUSION: Evaluation and quantitation of LV dilation in both control and cardiomyopathic mice can be reliably and serially performed using small-animal PET and (18)F-FDG, yielding useful functional information in addition to metabolic data.

Aging↗