Selectins Mediate Small Cell Lung Cancer Systemic Metastasis

Metastasis formation is the major reason for the extremely poor prognosis in small cell lung cancer (SCLC) patients. The molecular interaction partners regulating metastasis formation in SCLC are largely unidentified, however, from other tumor entities it is known that tumor cells use the adhesion molecules of the leukocyte adhesion cascade to attach to the endothelium at the site of the future metastasis. Using the human OH-1 SCLC line as a model, we found that these cells expressed E- and P-selectin binding sites, which could be in part attributed to the selectin binding carbohydrate motif sialyl Lewis A. In addition, protein backbones known to carry these glycotopes in other cell lines including PSGL-1, CD44 and CEA could be detected in in vitro and in vivo grown OH1 SCLC cells. By intravital microscopy of murine mesenterial vasculature we could capture SCLC cells while rolling along vessel walls demonstrating that SCLC cells mimic leukocyte rolling behavior in terms of selectin and selectin ligand interaction in vivo indicating that this mechanism might indeed be important for SCLC cells to seed distant metastases. Accordingly, formation of spontaneous distant metastases was reduced by 50% when OH-1 cells were xenografted into E-/P-selectin-deficient mice compared with wild type mice (p = 0.0181). However, as metastasis formation was not completely abrogated in selectin deficient mice, we concluded that this adhesion cascade is redundant and that other molecules of this cascade mediate metastasis formation as well. Using several of these adhesion molecules as interaction partners presumably make SCLC cells so highly metastatic.     

Identification of lucerne stem cell wall traits related to in vitro neutral detergent fibre digestibility

Genetic improvement of forage digestibility, especially utilizing marker assisted selection and recombinant DNA techniques, requires identification of specific biochemical traits and associated genes that impact digestibility. We undertook a study to identify cell wall (CW) traits of lucerne (Medicago sativa L.) stems that were consistently and strongly correlated with in vitro neutral detergent fibre (NDF) digestibility, a measurement that has been shown to correlate with animal performance. Spring and summer harvested lucerne stem material, for 2 years, from 24 individual plants in each of two germplasm sources were analyzed for 16 and 96 h in vitro NDF digestibility, and cell wall concentration and composition (monosaccharide constituents of cellulose, hemicellulose, and pectin; and Klason lignin (KL)) by the Uppsala dietary fibre method using near-infrared reflectance spectroscopy (NIRS). Pearson correlation coefficients were calculated for the relationships among these cell wall traits and with in vitro NDF digestibility. Concentrations of the pectin monosaccharide components were all negatively correlated (r=−0.73 to −0.94) with total cell wall concentration. In contrast, the three most abundant cell wall components glucose (Glc), xylose (Xyl) and Klason lignin were not correlated, or only weakly positively correlated (r<0.35), with cell wall concentration. Cell wall concentration was consistently negatively correlated (r=−0.60 to −0.94) with both 16 and 96 h in vitro NDF digestibility. In contrast, Klason lignin concentration was only marginally correlated (r<0.30) with 16 h in vitro NDF digestibility, but strongly negatively correlated (r=−0.71 to −0.74) with 96 h in vitro NDF digestibility. This is consistent with previous reports which show that lignin affects potential extent of digestion, but not rate. Cell wall glucose and xylose concentrations were inconsistently correlated with fibre digestibility. The monosaccharide components of pectin were consistently positively correlated (r=0.54–0.90) with in vitro NDF digestibility, except for 96 h in vitro NDF digestibility of spring harvested stems. Growth environment (year) and germplasm source had only minor impacts on the preceding correlation patterns, whereas spring versus summer harvests accounted for the inconsistencies observed among correlations for cell wall traits. The results of this study indicate that genetic improvement of fibre digestibility of lucerne stems should target genes that reduce total cell wall concentration, perhaps by reducing the rate of xylem tissue deposition during maturation, and reduce Klason lignin and increase pectin concentrations in the cell wall to improve potential extent and rate of fibre digestibility, respectively.     

Interference of the galactose-dependent binding of lectins by novel pentapeptide ligands

A library of pentapeptides containing the sequence -Y-X-Y- based on rational design was screened with six different lectins. Sequences were identified that modulate galectin binding to its natural carbohydrate ligand. SPR showed inhibition values 2-3 times stronger than galactose and NMR studies suggested real carbohydrate mimicry.     

Galectins as tools for glycan mapping in histology: comparison of their binding profiles to the bovine zona pellucida by confocal laser scanning microscopy

Gene divergence has given rise to the galectin family of mammalian lectins. Since selective binding to distinct β-galactosides underlies the known bioactivities of galectins, they could find application in cyto- and histochemistry. The pertinent question on the characteristics of their individual reactivity profiles therefore needs to be answered. Toward this end, comparative studies of a panel of galectins in defined systems are required. We here characterise the staining profiles of seven human lectins as well as five natural derivatives originating from proteolytic truncation and serine phosphorylation and one engineered variant. As test system, bovine germinal vesicle oocytes with their glycoprotein envelope (zona pellucida), which presents bi- to tetraantennary complex-type N-glycans with N-acetyllactosamine repeats and core fucosylation, were processed. Technically, confocal laser scanning microscopy was used, first with plant lectins to map the sialylation status. Hereby, α2,3/6-sialylation was detected in the superficial filamentous meshwork of the zona pellucida, while sialic acid-free glycan chains were found to characterise the main inner part of the compact layer of the zona pellucida. Galectin staining was specific and non-uniform. Significant differences in reactivity were detected for the superficial filamentous meshwork and the compact layer of the zona pellucida between galectins-1 to -4 versus galectins-8 and -9. The typical staining profiles intimate a spatially organised display of N-glycans in the different layers of the zona pellucida, underscoring the potential of galectins as cyto- and histochemical tools. Our results encourage further comparative analysis and research to trace the underlying structural and/or topological properties.     

Cholic acid-carboplatin compounds (CarboChAPt) as models for specific drug delivery: synthesis of novel carboplatin analogous derivatives and comparison of the cytotoxic properties with corresponding cisplatin compounds

This report continues our work on new compounds which consist of three functional parts--a transport fragment, a spacer and a biologically active 'drug' component. Here cholic acid functions as the transport fragment, linked via an alkyl spacer to a carboplatin analog, representing the drug (carbo-ChAPt-Fig. 1). We describe the synthesis and characterization of the series of complexes [Pt(Cyclobutane-1,1-dicarboxylato)(diamine)], [diamine=CholCOO(CH(2))(n)CH(CH(2)NH(2))(2) and THP(CH(2))(n)CH-(CH(2)NH(2))(2), n=4, 6, 8, 11]. The compounds were characterized by elemental analysis and NMR-measurements. Cytostatic activity data are given. In general, the cytostatic activity is similar to that of the parent compound and is strongly influenced by the length of the alkyl chain spacer separating the drug and transport fragments, the ones with long chain spacers being more toxic than the parent complexes. Preliminary investigations indicate the ability of the ChAPt to break resistance of tumor cells against common platinum tumor drugs, e.g. cisplatin. They are effective even on cell lines that have developed resistance to other drugs such as cis- and carboplatin. They are more cytotoxic so they are potentially effective at lower dose concentrations. The mode of cell death was examined by trypan-blue exclusion test and DNA gelelectrophoresis. Typical fragmentation of DNA was observed and the cells were still able to exclude trypan-blue.     

Sodium dependence of growth and methane formation in Methanobacterium thermoautotrophicum

Methanobacterium thermoautotrophicum was found to require sodium for growth and for CO₂ reduction to methane. The dependence of the rate of growth and methane formation on the sodium concentration was hyperbolic with an apparent K_s for sodium of approximately 1 mM. The findings indicate that sodium has a specific function in the energy metabolism of this bacterium.     

Metabolism of naphthalene by the biphenyl-degrading bacterium Pseudomonas paucimobilis Q1

Pseudomonas paucimobilis Q1 originally isolated as biphenyl degrading organism (Furukawa et al. 1983), was shown to grow with naphthalene. After growth with biphenyl or naphthalene the strain synthesized the same enzyme for the ring cleavage of 2,3-dihydroxybiphenyl or 1,2-dihydroxynaphthalene. The enzyme, although characterized as 2,3-dihydroxybiphenyl dioxygenase (Taira et al. 1988), exhibited considerably higher relative activity with 1,2-dihydroxynaphthalene. These results demonstrate that this enzyme can function both in the naphthalene and biphenyl degradative pathway.Abbreviations DHBP dihydroxybiphenyl - DHBPDO 2,3-dihydroxybiphenyl dioxygenase - DHDHNDH 1,2-dihydroxy-1,2-dihydronaphthalene dehydrogenase - DHN 1,2-dihydroxynaphthalene - DHNDO 1,2-dihydroxynaphthalene dioxygenase - HBP cis-2-hydroxybenzalpyruvate - HOPDA 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate - PCB polychlorinated biphenyl - 2NS naphthalene-2-sulfonic acid     

Maximum Number of Habitable Planets at the Time of Earth's Origin: New Hints for Panspermia?

New discoveries have fuelled the ongoing discussion of panspermia, i.e. the transport of life from one planet to another within the solar system (interplanetary panspermia) or even between different planetary systems (interstellar panspermia). The main factor for the probability of interstellar panspermia is the average density of stellar systems containing habitable planets. The combination of recent results for the formation rate of Earth-like planets with our estimations of extrasolar habitable zones allows us to determine the number of habitable planets in the Milky Way over cosmological time scales. We find that there was a maximum number of habitable planets around the time of Earth's origin. If at all, interstellar panspermia was most probable at that time and may have kick-started life on our planet.     

Selective and orally bioavailable phenylglycine tissue factor/factor VIIa inhibitors

We describe the structure-based design and synthesis of highly potent, orally bioavailable tissue factor/factor VIIa inhibitors which interfere with the coagulation cascade by selective inhibition of the extrinsic pathway.     

Developmental regulation of presence of binding sites for neoglycoproteins and endogenous lectins in various embryonic stages of human lung,liver and heart

Protein-carbohydrate interactions are supposed to play key roles in the mechanisms of cell adhesion, biosignalling and intracellular routing, warranting the analysis of the developmental course of expression of epitopes of this system. Thus, a panel of carrier-immobilized carbohydrate ligands was used as probes, namely lactose,N-acetylgalactosamine,N-acetylglucosamine, mannose, fucose and maltose. Additionally, an antibody to an endogenous -galactoside-binding lectin (anti-galectin-1), the biotinylated lectin and two further human lectins, namely the macrophage migration inhibitory factor-binding sarcolectin and serum amyloid P component (SAP) that displays selectivity for sulphated sugars and mannose-6-phosphate, were included. They enabled us to assess the extent of the presence of respective binding sites in fixed sections from human lungs (pulmonary epithelial cells), livers (hepatocytes) and hearts (myocard cells) of 10–50 weeks gestation. Invariably, specific binding was detected in the three organ types, at least in certain stages. In most of the cases, the intensity of staining exhibited developmental regulation. The apparent patterns reveal similarities between the different cell types, as seen with immobilizedN-acetylglucosamine as well as with labelled galectin-1 and sarcolectin. However, drastic differences among such patterns with nearly opposite developmental courses do also occur, as detected for carrier-attached mannose and maltose residues. These results point to a potential importance for the detected glycohistochemical features in human development and substantiate the possibility of differential regulation of the presence of binding sites for distinct sugars within a certain organ and between the individual cell types of the monitored organs.