Cell type-dependent alterations of binding of synthetic blood group antigen-related oligosaccharides in lung cancer

Synthesis of Carbohydrate Capped Silicon Nanoparticles and their Reduced Cytotoxicity, In Vivo Toxicity, and Cellular Uptake

The development of smart targeted nanoparticles (NPs) that can identify and deliver drugs at a sustained rate directly to cancer cells may provide better efficacy and lower toxicity for treating primary and advanced metastatic tumors. Obtaining knowledge of the diseases at the molecular level can facilitate the identification of biological targets. In particular, carbohydrate-mediated molecular recognitions using nano-vehicles are likely to increasingly affect cancer treatment methods, opening a new area in biomedical applications. Here, silicon NPs (SiNPs) capped with carbohydrates including galactose, glucose, mannose, and lactose are successfully synthesized from amine terminated SiNPs. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] analysis shows an extensive reduction in toxicity of SiNPs by functionalizing with carbohydrate moiety both in vitro and in vivo. Cellular uptake is investigated with flow cytometry and confocal fluorescence microscope. The results show the carbohydrate capped SiNPs can be internalized in the cells within 24 h of incubation, and can be taken up more readily by cancer cells than noncancerous cells. Moreover, these results reinforce the use of carbohydrates for the internalization of a variety of similar compounds into cancer cells.

Magnetic glyco-nanoparticles: a tool to detect, differentiate, and unlock the glyco-codes of cancer via magnetic resonance imaging

Within cancer, there is a large wealth of diversity, complexity, and information that nature has engineered rendering it challenging to identify reliable detection methods. Therefore, the development of simple and effective techniques to delineate the fine characteristics of cancer cells can have great potential impacts on cancer diagnosis and treatment. Herein, we report a magnetic glyco-nanoparticle (MGNP) based nanosensor system bearing carbohydrates as the ligands, not only to detect and differentiate cancer cells but also to quantitatively profile their carbohydrate binding abilities by magnetic resonance imaging (MRI). Using an array of MGNPs, a range of cells including closely related isogenic tumor cells, cells with different metastatic potential and malignant vs normal cells can be readily distinguished based on their respective "MRI signatures". Furthermore, the information obtained from such studies helped guide the establishment of strongly binding MGNPs as antiadhesive agents against tumors. As the interactions between glyco-conjugates and endogenous lectins present on cancer cell surface are crucial for cancer development and metastasis, the ability to characterize and unlock the glyco-code of individual cell lines can facilitate both the understanding of the roles of carbohydrates as well as the expansion of diagnostic and therapeutic tools for cancer.

Search for additional influenza virus to cell interactions

Sialyl oligosaccharides have long been considered to be the sole receptors for influenza virus. However, according to [1] some viruses are able to grow in sialic-free MDCK cells. Here we attempted to reveal a possible second, non-sialic receptor, hypothesizing the involvement of additional carbohydrate lectin recognition in influenza virus reception process, first of all in situations when a lectin of the host cell could recognize the viral carbohydrate ligand. We tested the presence of galactose- and sialic acid-binding lectins, as well as mannoside- and sulfo-N-acetyllactosamine-recognizing properties of MDCK and Vero cells using polyacrylamide neoglycoconjugates and antibodies. MDCK cells bind galactoside probes stronger than Vero cells, whereas Vero cells bind preferentially sialoside, mannoside and various sulfo-oligosaccharide probes. The probing of viruses with the neoglycoconjugates revealed specific 6'-HSO (3) LacNAc (but not other sulfated oligosaccharides) binding property of A and B human strains. Affinity of 6'-HSO (3) LacNAc probe was comparable with affinity of 6'-SiaLac probe but the binding was not inhibited by the sialooligosaccharide.

Glycohistochemistry: the why and how of detection and localization of endogenous lectins

The central dogma of molecular biology limits the downstream flow of genetic information to proteins. Progress from the last two decades of research on cellular glycoconjugates justifies adding the enzymatic production of glycan antennae with information-bearing determinants to this famous and basic pathway. An impressive variety of regulatory processes including cell growth and apoptosis, folding and routing of glycoproteins and cell adhesion/migration have been unravelled and found to be mediated or modulated by specific protein (lectin)-carbohydrate interactions. The conclusion has emerged that it would have meant missing manifold opportunities not to recruit the sugar code to cellular information transfer. Currently, the potential for medical applications in anti-adhesion therapy or drug targeting is one of the major driving forces fuelling progress in glycosciences. In histochemistry, this concept has prompted the introduction of carrier-immobilized carbohydrate ligands (neoglycoconjugates) to visualize the cells' capacity to be engaged in oligosaccharide recognition. After their isolation these tissue lectins will be tested for ligand analysis. Since fine specificities of different lectins can differ despite identical monosaccharide binding, the tissue lectins will eventually replace plant agglutinins to move from glycan profiling and localization to functional considerations. Namely, these two marker types, i.e. neoglycoconjugates and tissue lectins, track down accessible binding sites with relevance for involvement in interactions in situ. The documented interplay of synthetic organic chemistry and biochemistry with cyto- and histochemistry nourishes the optimism that the application of this set of innovative custom-prepared tools will provide important insights into the ways in which glycans can act as hardware in transmitting information during normal tissue development and pathological situations.

Binding sites for carrier-immobilized carbohydrates in the kidney: implication for the pathogenesis of Henoch-Schönlein purpura and/or IgA nephropathy

BACKGROUND

Henoch-Schönlein purpura is a common vasculitis of childhood affecting the skin, joints, gastrointestinal tract, and kidney. The mesangial deposition of IgA1 is the most critical factor for the prognosis of patients with this disease. The aberrant glycosylation of the IgA1 subclass with the absence of terminally located galactose and presence of only alpha-N-acetylgalactosamine in O-linked oligosaccharides in the hinge region of IgA1 represents a prominent difference from the normal IgA1. These alterations prompt the supposition that the sugar part may guide IgA deposition by recognition of endogenous lectins on the mesangium.

METHODS

Owing to the limited knowledge about the expression of carbohydrate-binding sites in the human kidney we initiated the study of this aspect with a class of tools which are suitable to map the lectinome of cells. Employing biotinylated neoglycoconjugates, glycosaminoglycans, and sulphated polysaccharides we monitored the presence of accessible carbohydrate-binding sites in control kidneys represented by tumour-free areas of kidneys with Grawitz tumour and in biopsies from patients with Henoch-Schönlein purpura-associated IgA nephropathy.

RESULTS

Using frozen sections, no expression of any tested carbohydrate-binding site(s) was observed in the endothelial and the mesangial cells in glomeruli of the control kidneys as well as in the biopsies from Henoch-Schönlein purpura IgA nephropathic kidneys, in contrast to the tubules. The N-acetylgalactosamine-binding sites were expressed only in the inner layer of Bowman's capsule of 20% of glomeruli of the control kidney from one patient with Grawitz tumour and one biopsy from a patient with Henoch-Schönlein purpura-associated IgA nephropathy. However, the macrophages in the glomeruli of patients with IgA nephropathy and interstitial macrophages from both studied groups, i.e. without and with IgA nephropathy, harbour capacity to recognize carrier-immobilized alpha-N-acetylgalactosamine. Access to this binding site for the neoligand conjugate can be blocked by the monoclonal antibody MEM-18 recognizing CD14 antigen.

CONCLUSION

The possibility for a participation of macrophage deposition of IgA1 in mesangium via a lectin mechanism involving this binding capacity warrants further studies.

Polyacrylamide-based glycoconjugates as tools in glycobiology

This review describes the synthesis, physicochemical characteristics and application for studying carbohydrate-binding proteins of polyacrylamide (PAA) type neoglycoconjugates. An approach to the synthesis of conjugates based on the interaction of activated polyacrylic acid with omega-aminoalkyl glycosides has been developed. Both the molecules of Glyc-PAA and the conjugates bearing various labels and effectors, as well as sorbents, and glycosurfaces can be designed using this method. Examples of the application of the conjugates as tools for the study of lectins, antibodies, and glycosyltransferases in glycobiology, cytochemistry and histochemistry are described along with the prospects of the further development of the presented approach in glycotechnology and medicine.

Application of computer-assisted morphometry to the analysis of prenatal development of human lung

Morphometry is well-established in tumour pathology. To evaluate is potential usefulness for description of developmental processes, histological slides from paraffin-embedded specimens of 67 human fetal lungs were Feulgen-stained, and morphometric characteristics of nuclei of epithelial pulmonary cells were analysed with an automated image analysis system. The measured cytometric features comprised of integrated optical density (IOD), S-phase-related IOD fraction, IOD entropy and nuclear area. Histometric features of the specimens were based upon the minimum spanning tree (MST) and included distances between neighboring epithelial cells, between epithelial cells and neighboring lymphocytes, and assessment of MST entropy. Notably, certain parameters revealed a non-uniform level during prenatal development S-phase-related IOD fraction increased from 5% to 8% between 14 and 16 weeks of gestation, then declined to 6% until birth. The IOD entropy steadily increased during development, whereas the extent of nuclear area remained constant. In accordance with an increase of the S-phase-related fraction the MST entropy displayed a singular peak between 14 and 16 weeks of gestation, which is probably associated with development of glandular structures in the lung. Correlation of expression of binding sites for markers, presumably involved in functional aspects of development, with such alterations, is shown for binding capacities of biotinylated fucoidan and the S-phase-related fraction. This may be helpful to infer immuno- or ligando histochemically defined tissue sites with potential physiological significance in morphometrically distinguished periods of development.

Binding capacities of two immunomodulatory lectins, carrier-immobilized glycoligands and steroid hormones in lung cancer and the concentration of nitrite/nitrate in pleural effusions

Combined analysis of the binding properties of inflammatory and tumor cells in pleural effusion, and tumor imprints for various carrier-immobilized types of ligands and lectins, and of a biochemical feature of the effusions is performed to extend the characterization of these cells and their activity. In detail, the binding of Viscum album agglutinin (VAA), Urtica dioica agglutinin (UDA), and of carrier-immobilized N-acetyl-D-glucosamine (GlcNAc), lysoganglioside GM1, estradiol, progesterone, testosterone, and hydrocortisone to native specimens consisting of 46 tumor imprints from surgically treated patients with lung cancer and 74 smears of pleural effusion (PE) cells from cancer or non-cancer patients was studied using fluorescence microscopy with Texas red-labeled streptavidin. Among the tested ligands, VAA was found to provide the most effective staining of cells (60-78.1% of positive cases). When compared with inflammatory cells from PE, cancer cells were seen to bind more frequently only two ligands, namely UDA and estradiol. Significant (P < 0.001) difference between patients with bronchial carcinoma and non-cancer patients were found, when the content of NO2-/NO3- in PE fluids was measured. Whereas the level of NO2-/NO3- in PE of non-cancer patients was 12.6 +/- 10.7 microM (n = 12), it was 37.7 +/- 19.4 microM (n = 14) in cancer patients without pleural metastases and 37.5 +/- 16.0 microM (n = 26) in patients with pleural metastases. The level of NO2-/NO3- in PE appeared to correlate with extent of staining with GM1 and GlcNAc: in non-cancer patient groups it was significantly higher (P = 0.032) for negative subjects than those binding the ligand GlcNAc, whereas in the patient group with adenocarcinoma it was significantly lower (P = 0.032) for patients without binding capacities for GlcNAc and GM1. The results obtained suggest that the combined analysis of increased levels of NO2-/NO3- in PE and of glycohistochemical properties of cancer and inflammatory cells may be useful in exploring the interrelationship of functionally important cellular characteristics.