Expression regulation of MAO isoforms in monocytic cells in response to Th2 cytokines

Background: Th2-cytokines, such as interleukins-4 and –13 (IL-4, IL-13), have been identified as alternative stimuli of monocytes/macrophages. We have recently profiled the gene-expression pattern of IL-4-teated human peripheral monocytes and found that 15-lipoxygenase-1 (15-LOX1) and monoamine oxidase A (MAO-A) are among the five most strongly upregulated gene products in IL-4-treated cells. Transfection of monocytic cells (U937) with 15-LOX1 also induced MAO-A expression. These data suggested that 15-LOX1 products might play a role in the IL4-induced signaling cascade leading to expression of MAO-A in human monocytes. Material/Methods: To test this hypothesis we incubated wild-type and 15-LOX1-transfected U937 cells with different concentrations of either IL-4 or 15-LOX-products [13S-H(p)ODE, 15S-H(p)ETE] and quantified the expression of 15-LOX1, MAO-A, and MAO-B by activity assays and real-time RT-PCR. Results: Wild-type U937 cells express neither MAO-A nor MAO-B, but after three days of IL4 treatment, MAO-A mRNA was detected. A similar isoform-specific expression of MAO-A mRNA was observed when U937 cells were transfected with 15-LOX1 or when the cells were incubated with primary 15-LOX1 products (hydroperoxy fatty acids) or H2O2. In contrast, the corresponding hydroxy fatty acids were ineffective. Conclusions: These data indicate that increased intracellular peroxide concentrations (oxidative stress) induce MAO-A expression in monocytes/macrophages, which normally do not express the enzyme. Our findings also suggest that IL-4-induced upregulation of MAO-A expression in human peripheral monocytes may proceed via 15-LOX1-dependent and 15-LOX1-independent pathways. The biological role of MAO-A expression for monocyte function is discussed

Inhibition of the defense system stimulating interleukin-12 interferon-γ pathway during critical illness.

Interleukin-12 (IL-12) and interferon-gamma (IFN-gamma) exert protective effects during experimental endotoxemia through upregulation of cellular immunity and phagocytic functions. They are part of a positive regulatory feedback loop that enhances the production of the other. Because critically ill patients show a marked suppression of T-cell and macrophage functions with a high susceptibility to infection, potential defects in the immunity/inflammation upregulating IL-12 IFN-gamma pathway were studied. As an ex vivo model of endotoxemia, lipopolysaccharide (LPS) stimulated whole blood from 25 critically ill patients and 12 healthy individuals was incubated with either recombinant human (rh) IL-12 or rhIFN-gamma, respectively. IFN-gamma dose-dependently (P < .05) increased the release of IL-12 p40 and p70 into LPS-stimulated whole blood from healthy humans without effect in whole blood from critically ill patients. RhIL-12 p70 enhanced (P < .05) the secretion of IFN-gamma in controls, while it was ineffective in LPS-stimulated whole blood from critically ill patients. The observed inhibition of the IL-12 IFN-gamma pathway is not specific to LPS, since Staphylococcus aureus Cowan strain I (SAC)-stimulated whole blood from critically ill patients showed similar suppression. The secretion of IL-12 and IFN-gamma was less reduced in critically ill patients when using isolated cultures of adherent cells or lymphocytes. Although preculture of whole blood from healthy humans with IL-10, but not with IL-4, mimicked suppression of the IL-12 IFN-gamma pathway similar to that observed during critical illness, the release of antiinflammatory reacting cytokines (IL-4, IL-10, transforming growth factor [TGF]-beta 1) was decreased into LPS-stimulated whole blood from critically ill patients. These results indicate at least two mechanisms responsible for dramatic disturbances of the IL-12 IFN-gamma pathway during critical illness: (1) deactivation of IL-12 and IFN-gamma producing leukocytes in vivo early after the primary insult, and (2) presence of serum suppressive factors different from IL-4, IL-10, or TGF-beta 1. Because IL-12 and IFN-gamma upregulate essential immune functions, the marked inhibition of IL-12 and IFN-gamma release may be pivotal for high susceptibility of critically ill patients to infection

Antihypoxic potentiation of standard therapy for experimental colorectal liver metastasis through myo-inositol trispyrophosphate

PURPOSE: Tumor hypoxia activates hypoxia-inducible factors (Hifs), which induce a range of malignant changes including vascular abnormalities. Here, we determine whether inhibition of the hypoxic tumor response through myo-inositol trispyrophosphate (ITPP), a compound with antihypoxic properties, is able to cause prolonged vascular normalization that can be exploited to improve standard-of-care treatment. EXPERIMENTAL DESIGN: We tested ITPP on two syngeneic orthotopic mouse models of lethal colorectal cancer liver metastasis. Tumors were monitored by MRI and analyzed for the hypoxic response and their malignant potential. A Hif activator and in vitro assays were used to define the working mode of ITPP. Hypoxic response and vasculature were re-evaluated 4 weeks after treatment. Finally, we determined survival following ITPP monotherapy, FOLFOX monotherapy, FOLFOX plus Vegf antibody, and FOLFOX plus ITPP, both overlapping and sequential. RESULTS: ITPP reduced tumor load, efficiently inhibited the hypoxic response, and improved survival. These effects were lost when mice were pretreated with a Hif activator. Its immediate effects on the hypoxic response, including an apparent normalization of tumor vasculature, persisted for at least 4 weeks after treatment cessation. Compared with FOLFOX alone, Vegf antibody combined with FOLFOX prolonged survival by 140%, regardless of whether FOLFOX was given in overlap or after ITPP exposure. CONCLUSIONS: Our findings reveal a truly antihypoxic mechanism for ITPP and demonstrate the capacity of this nontoxic compound to potentiate the efficacy of existing anticancer treatment in a way amenable to clinical translation. Clin Cancer Res; 22(23); 5887-97

De novo expression of EphA2 in osteosarcoma modulates activation of the mitogenic signalling pathway

AIMS: In osteosarcoma patients the development of metastases, often to the lungs, is the most frequent cause of death. The aim of this study was to elucidate the molecular mechanisms governing osteosarcoma development and dissemination and, thereby, to identify possible novel drug targets for improved treatment. METHODS AND RESULTS: Osteosarcoma samples were characterized using genome-wide microarrays: increased expression of the EphA2 receptor and its ligand EFNA1 was detected. In addition, increased expression of EFNB1, EFNB3 and EphA3 was suggested. Immunohistochemistry revealed an absence of EphA2 in normal bone, and de novo expression in osteosarcomas. EFNA1 was expressed in normal bone, but was significantly elevated in tumours. Further in vitro investigations on the functional role of EphA2 and EFNA1 showed that EFNA1 ligand binding induced increased tyrosine phoshorylation, receptor degradation and downstream mitogen-activated protein kinase (MAPK) activation. Interference with the MAPK pathway unravelled a potential autoregulatory loop governing mainly EFNA1 expression via the same pathway. CONCLUSION: Upregulation and de novo expression of ephrins in osteosarcomas are involved in oncogenic signalling and thus might stimulate osteosarcoma metastasis

Entwicklung und Konstruktion einer Vorrichtung zum Herstellen eines Mischhauttransplantates zur Deckung grossflaechiger Verbrennungswunden Schlussbericht

SIGLEAvailable from TIB Hannover: FR 5152+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

STAT3 and MAPK signaling maintains overexpression of the heat shock proteins 90a and b in multiple myeloma cells, which critically contribute to tumor cell survival

The combined blockade of the IL-6R/STAT3 and the MAPK signaling pathways has been shown to inhibit bone marrow microenvironment (BMM)-mediated survival of multiple myeloma (MM) cells. Here, we identify the molecular chaperones heat shock protein (Hsp) 90alpha and beta as target genes of both pathways. SiRNA-mediated knockdown of Hsp90 or treatment with the novel Hsp90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. Although knockdown of Hsp90beta -- unlike knockdown of Hsp90alpha -- was sufficient to induce apoptosis, this effect was strongly increased when both Hsp90s were targeted, indicating a cooperation of both. Given the importance of the BMM for drug resistance and MM cell survival, apoptosis induced by Hsp90 inhibition was not mitigated in the presence of bone marrow stromal cells, osteoclasts or endothelial cells. These observations suggest, that a positive feedback loop consisting of Hsp90alpha/beta and major signaling pathways supports the survival of MM cells. Finally, in situ overexpression of both Hsp90 proteins was observed in the majority of MM, but not in MGUS or in normal plasma cells. Our results underpin a role for Hsp90alpha and beta in MM pathogenesis

Physiol Genomics

Rheumatoid arthritis (RA) is a chronic, inflammatory joint disease of unknown etiology and pronounced inter-patient heterogeneity. To characterize RA at the molecular level and to uncover pathomechanisms, we performed genome-wide gene expression analysis. We identified a set of 1054 genes significantly deregulated in pair-wise comparisons between RA and osteoarthritis (OA) patients, RA and normal donors (ND), or OA and ND. Correlation analysis revealed gene sets regulated identically in all three groups. As a prominent example secreted phosphoprotein 1 (SPP1) was identified to be significantly upregulated in RA as compared to both OA and ND. SPP1 expression was found to correlate with genes expressed during an inflammatory response, T cell activation and apoptosis, suggesting common underlying regulatory networks. A sub-classification of RA patients was achieved on the basis of proteoglycan 4 (PRG4) expression distinguishing PRG4 high- and low expressors and reflecting the heterogeneity of the disease. In addition, we found that low PRG4 expression was associated with a more aggressive disease stage, which is in accordance with PRG4 loss-of-function mutations causing camptodactyly-arthropathy-coxa vara-pericarditis syndrome. Altogether we provide evidence for molecular signatures of RA and RA subclasses, sets of new candidate genes as well as for candidate gene networks, which extend our understanding of disease mechanisms and may lead to an improved diagnosis