Signal transduction, receptors, mediators and genes: younger than ever - the 13th meeting of the Signal Transduction Society focused on aging and immunology

The 13th meeting of the Signal Transduction Society was held in Weimar, from October 28 to 30, 2009. Special focus of the 2009 conference was "Aging and Senescence", which was co-organized by the SFB 728 "Environmentally-Induced Aging Processes" of the University of Düsseldorf and the study group 'Signal Transduction' of the German Society for Cell Biology (DGZ). In addition, several other areas of signal transduction research were covered and supported by different consortia associated with the Signal Transduction Society including the long-term associated study groups of the German Society for Immunology and the Society for Biochemistry and Molecular Biology, and for instance the SFB/Transregio 52 "Transcriptional Programming of Individual T Cell Subsets" located in Würzburg, Mainz and Berlin. The different research areas that were introduced by outstanding keynote speakers attracted more than 250 scientists, showing the timeliness and relevance of the interdisciplinary concept and exchange of knowledge during the three days of the scientific program. This report gives an overview of the presentations of the conference

Tumor interactions with soluble factors and the nervous system

In the genomic era of cancer research, the development of metastases has been attributed to mutations in the tumor that enable the cells to migrate. However, gene analyses revealed that primary tumors and metastases were in some cases genetically identical and the question was raised whether metastasis formation might be an inherent feature of certain tumor cells. In contradiction to this view, the last decade of cancer research has brought to light, that tumor cell migration, similar to leukocyte and fibroblast migration, is a highly regulated process. The nervous system plays an important role in this regulation, at least in two respects: firstly, neurotransmitters are known to regulate the migratory activity of tumor cells, and secondly, nerve fibers are used as routes for perineural invasion. We also summarize here the current knowledge on the innervation of tumors. Such a process might establish a neuro-neoplastic synapse, with the close interaction of tumor cells and nerve cells supporting metastasis formation

Effect of staurosporine on the mobility and invasiveness of lung adenocarcinoma A549 cells: an in vitro study

<p>Abstract</p> <p>Background</p> <p>Lung cancer is one of the most malignant tumors, representing a significant threat to human health. Lung cancer patients often exhibit tumor cell invasion and metastasis before diagnosis which often render current treatments ineffective. Here, we investigated the effect of staurosporine, a potent protein kinase C (PKC) inhibitor on the mobility and invasiveness of human lung adenocarcinoma A549 cells.</p> <p>Methods</p> <p>All experiments were conducted using human lung adenocarcinoma A549 cells that were either untreated or treated with 1 nmol/L, 10 nmol/L, or 100 nmol/L staurosporine. Electron microscopy analyses were performed to study ultrastructural differences between untreated A549 cells and A549 cells treated with staurosporine. The effect of staurosporine on the mobility and invasiveness of A549 was tested using Transwell chambers. Western blot analyses were performed to study the effect of staurosporine on the levels of PKC-α, integrin β1, E-cadherin, and LnR. Changes in MMP-9 and uPA levels were identified by fluorescence microscopy.</p> <p>Results</p> <p>We demonstrated that treatment of A549 cells with staurosporine caused alterations in the cell shape and morphology. Untreated cells were primarily short spindle- and triangle-shaped in contrast to staurosporine treated cells which were retracted and round-shaped. The latter showed signs of apoptosis, including vacuole fragmentation, chromatin degeneration, and a decrease in the number of microvilli at the surface of the cells. The A549 cell adhesion, mobility, and invasiveness significantly decreased with higher staurosporine concentrations. E-cadherin, integrin β1, and LnR levels changed by a factor of 1.5, 0.74, and 0.73, respectively compared to untreated cells. In addition, the levels of MMP-9 and uPA decreased in cells treated with staurosporine.</p> <p>Conclusion</p> <p>In summary, this study demonstrates that staurosporine inhibits cell adhesion, mobility, and invasion of A549 cells. The staurosporine-mediated inhibition of PKC-α, induction of E-Cad expression, and decreased integrin β1, LnR, MMP-9, and uPA levels could all possibly contribute to this biological process. These results represent a significant step forward in the ongoing effort to understand the development of lung carcinoma and to design novel strategies to inhibit metastasis of the tumor by targeting the cell-adhesion, mobility and invasion of tumor cells.</p

Extravasation of leukocytes in comparison to tumor cells

The multi-step process of the emigration of cells from the blood stream through the vascular endothelium into the tissue has been termed extravasation. The extravasation of leukocytes is fairly well characterized down to the molecular level, and has been reviewed in several aspects. Comparatively little is known about the extravasation of tumor cells, which is part of the hematogenic metastasis formation. Although the steps of the process are basically the same in leukocytes and tumor cells, i.e. rolling, adhesion, transmigration (diapedesis), the molecules that are involved are different. A further important difference is that leukocyte interaction with the endothelium changes the endothelial integrity only temporarily, whereas tumor cell interaction leads to an irreversible damage of the endothelial architecture. Moreover, tumor cells utilize leukocytes for their extravasation as linkers to the endothelium. Thus, metastasis formation is indirectly susceptible to localization signals that are literally specific for the immune system. We herein compare the extravasation of leukocytes and tumor cells with regard to the involved receptors and the localization signals that direct the cells to certain organs and sites of the body

Signal transduction in cells of the immune system in microgravity

Life on Earth developed in the presence and under the constant influence of gravity. Gravity has been present during the entire evolution, from the first organic molecule to mammals and humans. Modern research revealed clearly that gravity is important, probably indispensable for the function of living systems, from unicellular organisms to men. Thus, gravity research is no more or less a fundamental question about the conditions of life on Earth. Since the first space missions and supported thereafter by a multitude of space and ground-based experiments, it is well known that immune cell function is severely suppressed in microgravity, which renders the cells of the immune system an ideal model organism to investigate the influence of gravity on the cellular and molecular level. Here we review the current knowledge about the question, if and how cellular signal transduction depends on the existence of gravity, with special focus on cells of the immune system. Since immune cell function is fundamental to keep the organism under imnological surveillance during the defence against pathogens, to investigate the effects and possible molecular mechanisms of altered gravity is indispensable for long-term space flights to Earth Moon or Mars. Thus, understanding the impact of gravity on cellular functions on Earth will provide not only important informations about the development of life on Earth, but also for therapeutic and preventive strategies to cope successfully with medical problems during space exploration

Leptin and Adiponectin: new players in the field of tumor cell and leukocyte migration

Adipose tissue is no longer considered to be solely an energy storage, but exerts important endocrine functions, which are primarily mediated by a network of various soluble factors derived from fat cells, called adipocytokines. In addition to their responsibility to influence energy homeostasis, new studies have identified important pathways linking metabolism with the immune system, and demonstrating a modulatory role of adipocytokines in immune function. Additionally, epidemiological studies underline that obesity represents a significant risk factor for the development of cancer, although the exact mechanism of this relationship remains to be determined. Whereas a possible influence of adipocytokines on the proliferation of tumor cells is already known, new evidence has come to light elucidating a modulatory role of this signaling substances in the regulation of migration of leukocytes and tumor cells. The migration of leukocytes is a key feature to fight cancer cells, whereas the locomotion of tumor cells is a prerequisite for tumor formation and metastasis. We herein review the latest tumor biological findings on the role of the most prominent adipocytokines leptin and adiponectin, which are secreted by fat cells, and which are involved in leukocyte migration, tumor growth, invasion and metastasis. This review thus accentuates the complex, interactive involvement of adipocytokines in the regulation of migration of both leukocytes and tumor cells, and gives an insight in the underlying molecular mechanisms

Luminal and basal-like breast cancer cells show increased migration induced by hypoxia, mediated by an autocrine mechanism

<p>Abstract</p> <p>Background</p> <p>Some breast cancer patients receiving anti-angiogenic treatment show increased metastases, possibly as a result of induced hypoxia. The effect of hypoxia on tumor cell migration was assessed in selected luminal, post-EMT and basal-like breast carcinoma cell lines.</p> <p>Methods</p> <p>Migration was assessed in luminal (MCF-7), post-EMT (MDA-MB-231, MDA-MB-435S), and basal-like (MDA-MB-468) human breast carcinoma cell lines under normal and oxygen-deprived conditions, using a collagen-based assay. Cell proliferation was determined, secreted cytokine and chemokine levels were measured using flow-cytometry and a bead-based immunoassay, and the hypoxic genes HIF-1α and CA IX were assessed using PCR. The functional effect of tumor-cell conditioned medium on the migration of neutrophil granulocytes (NG) was tested.</p> <p>Results</p> <p>Hypoxia caused increased migratory activity but not proliferation in all tumor cell lines, involving the release and autocrine action of soluble mediators. Conditioned medium (CM) from hypoxic cells induced migration in normoxic cells. Hypoxia changed the profile of released inflammatory mediators according to cell type. Interleukin-8 was produced only by post-EMT and basal-like cell lines, regardless of hypoxia. MCP-1 was produced by MDA-MB-435 and -468 cells, whereas IL-6 was present only in MDA-MB-231. IL-2, TNF-α, and NGF production was stimulated by hypoxia in MCF-7 cells. CM from normoxic and hypoxic MDA-MB-231 and MDA-MB-435S cells and hypoxic MCF-7 cells, but not MDA-MB-468, induced NG migration.</p> <p>Conclusions</p> <p>Hypoxia increases migration by the autocrine action of released signal substances in selected luminal and basal-like breast carcinoma cell lines which might explain why anti-angiogenic treatment can worsen clinical outcome in some patients.</p

Rapid Immunomagnetic Negative Enrichment of Neutrophil Granulocytes from Murine Bone Marrow for Functional Studies In Vitro and In Vivo

Polymorphonuclear neutrophils (PMN) mediate early immunity to infection but can also cause host damage if their effector functions are not controlled. Their lack or dysfunction is associated with severe health problems and thus the analysis of PMN physiology is a central issue. One prerequisite for PMN analysis is the availability of purified cells from primary organs. While human PMN are easily isolated from peripheral blood, this approach is less suitable for mice due to limited availability of blood. Instead, bone marrow (BM) is an easily available reservoir of murine PMN, but methods to obtain pure cells from BM are limited. We have developed a novel protocol allowing the isolation of highly pure untouched PMN from murine BM by negative immunomagnetic isolation using a complex antibody cocktail. The protocol is simple and fast (∼1 h), has a high yield (5–10*106 PMN per animal) and provides a purity of cells equivalent to positive selection (>80%). Most importantly, cells obtained by this method are non-activated and remain fully functional in vitro or after adoptive transfer into recipient animals. This method should thus greatly facilitate the study of primary murine PMN in vitro and in vivo

Interstitial cell migration: integrin-dependent and alternative adhesion mechanisms

Adhesion and migration are integrated cell functions that build, maintain and remodel the multicellular organism. In migrating cells, integrins are the main transmembrane receptors that provide dynamic interactions between extracellular ligands and actin cytoskeleton and signalling machineries. In parallel to integrins, other adhesion systems mediate adhesion and cytoskeletal coupling to the extracellular matrix (ECM). These include multifunctional cell surface receptors (syndecans and CD44) and discoidin domain receptors, which together coordinate ligand binding with direct or indirect cytoskeletal coupling and intracellular signalling. We review the way that the different adhesion systems for ECM components impact cell migration in two- and three-dimensional migration models. We further discuss the hierarchy of these concurrent adhesion systems, their specific tasks in cell migration and their contribution to migration in three-dimensional multi-ligand tissue environments

Developmental and Lactational Exposure to Dieldrin Alters Mammary Tumorigenesis in Her2/neu Transgenic Mice

Breast cancer is the most common cancer in Western women and while its precise etiology is unknown, environmental factors are thought to play a role. The organochlorine pesticide dieldrin is a persistent environmental toxicant thought to increase the risk of breast cancer and reduce survival in the human population. The objective of this study was to define the effect of developmental exposure to environmentally relevant concentrations of dieldrin, on mammary tumor development in the offspring. Sexually mature FVB-MMTV/neu female mice were treated with vehicle (corn oil), or dieldrin (0.45, 2.25, and 4.5 µg/g body weight) daily by gavage for 5 days prior to mating and then once weekly throughout gestation and lactation until weaning. Dieldrin concentrations were selected to produce serum levels representative of human background body burdens, occupational exposure, and overt toxicity. Treatment had no effect on litter size, birth weight or the number of pups surviving to weaning. The highest dose of dieldrin significantly increased the total tumor burden and the volume and number of tumors found in the thoracic mammary glands. Increased mRNA and protein expression of the neurotrophin BDNF and its receptor TrkB was increased in tumors from the offspring of dieldrin treated dams. This study indicates that developmental exposure to the environmental contaminant dieldrin causes increased tumor burden in genetically predisposed mice. Dieldrin exposure also altered the expression of BNDF and TrkB, novel modulators of cancer pathogenesis