Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The agglutinating effect of lectin from mistletoe (Viscum album L.) relative to erythrocytes and tumor cells is destroyed or reduced by plasma proteins. There is a competition between lectin receptors of plasma proteins, especially immunoglobulins and erythrocytes, as well as tumor cells. The preparation of insolubilized immunoglobin fractions allows one to separate lectin from the mistletoe extract. There exist chemical connections between the lectin fixed to the adsorbent and part of the toxic components.
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PMID:[Isolation and characterization of mistletoe extracts (Viscum album L.). I. Affinity chromatography of mistletoe extracts on immobilized plasma proteins]. 87 40

We have investigated the receptor site activity present on 6C3HED tumor cells for concanavalin A, fava, lentil and pea lectins. The binding of the tritiated lectins to the tumor cells was inhibited by methyl-alpha-D-mannoside but not by D-galactose. The number of binding sites for the lectins was 3.5-10(6)/cell for concanavalin A, 3.3-10(6)/cell for fava, 3.6-10(6)/cell for lentil and 4.8-10(6)/cell for pea. The apparent association constants were 3.6 and 1.3 muM-1 for concanavalin A, 3.9 muM-1 for fava, 4.2 muM-1 for lentil and 4.6 and 0.6 muM-1 for pea. Competitive inhibition studies showed that lentil was a good inhibitor of pea binding; concanavalin A was a poor inhibitor of pea binding; and fava was a better inhibitor than concanavalin A but not as good as lentil. Reciprocal inhibition experiments indicated that concanavalin A and pea may bind to different receptors as well as to common receptors. This was also indicated by the observation that trypsin or protease treatment of the cells decreased the binding of pea lectin by 20-40 percent whereas concanavalin A binding was unaffected.
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PMID:Studies on 6C3HED murine ascites tumor cell receptors for mannosyl-binding lectins. 95 11

One approach to effective cancer chemotherapy is to maximize the exposure of tumor cells to cytotoxic drugs while minimizing the exposure of sensitive normal cells to such agents. This implies the need for control of the pharmacodynamics of anti-tumor drugs in terms of blood clearance kinetics, disposition in tissues, passage across membrane barriers, and interaction with metabolic pathways. A promising approach to pharmacodynamic control is the microencapsulation of drugs within liposomes. The clearance kinetics and tissue disposition of the drug is then dictated by the pharmacokinetic behavior of the liposomal carrier. The blood clearance rates and tissue uptake of liposomes themselves depend upon physical characteristics such as particle size and surface charge. It is also possible to promote specific interaction between cells and liposomes in vitro by preparing liposomes containing biological macromolecules such as lectin receptors. The potentialities of microencapsulation as an adjunct to chemotherapy are discussed.
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PMID:The role of drug delivery systems in cancer chemotherapy. 103 Aug 1

A method potentially capable of enhancing the effectiveness of therapeutic enzymes such as L-asparaginase was investigated. The method was suggested by the following properties that have been observed for lectins injected into tissues: (1) six lectins with differing specificities were retained near the site of injection in the feet of mice 10 to 100 times longer than several non-lectin proteins. Prolonged retention of 125I-labelled concanavalin A was also observed in other normal and malignant mouse tissues. (2) The retention of 125I-labelled concanavalin A was not affected by prior immunization against concanavalin A. (3) Electrophoresis of tissue extracts on sodium dodecyl sulfate-poly-acrylamide gels followed by radioautography indicated that the 125I-labelled concanavalin A retained in the tissue remained as intact in form as prior to injection. Since the therapeutic efficacy of many enzymes may be enhanced by localization at the intended site of action, in principle it should be possible to enhance the effectiveness of therapeutic enzymes by combining the tissue-localizing properties of a lectin with therapeutic effectiveness of the enzyme. A conjugate of E. coli L-asparaginase and concanavalin A has been prepared by covalent cross-linking with glutaraldehyde and has been shown to be retained in mouse tissue 90 times longer than the free enzyme. However, it is completely ineffective in the treatment of the L-asparaginase-sensitive lymphosarcoma 6C3HED in C3H/HeJ mice. The ineffectiveness of the conjugated enzyme may be associated with the interiorization of the conjugate by the cells of the tumor.
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PMID:Effect of localization of L-asparaginase as the concanavalin A conjugate on anti-tumor activity. 103 89

How does Con A affect the cellular dynamics and cellular transport of various substances? It has been observed that following a 30 minute incubation with Con A (20-66 mug/ml) the tumor cells (Anaplastic carcinoma Type 15091a), unlike the normal cells, gradually retract their pseudopodia, take on a rounded shape and lose their motility. The maximum rounding of tumor cells takes place during the period of 200-250 min following the withdrawal of Con A from the incubating medium. All of these rounded cells later develop their regular pseudopodia. A partial synchrony of cell division is also observed. Associated with the rounding effect, there is a decrease in the rate of uptake of some specific amino acids by the tumor cells. The maximum reduction in the uptake coincides with the stage of maximum rounding. Con A also affects some of the electrical properties of tumor cells. In addition, the incorporation of radioactive thymidine into the nuclei is reduced to a much larger extent than can be accounted for by the reduction in the rate of entry of thymidine into cytoplasm. The saturation densities of both normal and tumor cells are not significantly altered by Con A. Tumor cells treated with Con A (chronically or acutely) are equally as potent as the untreated cells in yielding solid tumors when the host animals are injected with these cell subcutaneously. In conclusion, it is suggested that while Con A does not revert or destroy this particular line of tumor cells, this lectin has some interesting selective effects on the morphology and transport properties of tumor cells.
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PMID:Effects of concanavalin A on cellular dynamics and membrane transport. 109 12

The use of Lens culinaris lectin for electron microscopic detection of D-mannose,- D-glucose and N-acetyl-D-glucosamine like sites on tumor cells, erythrocytes, erythrocyte ghosts, cultured rat liver cells and various tissues of mice is demonstrated. In addition to Lens culinaris lectin-peroxidase reaction (LeL-po reaction) the preparation of active Lens culinaris lectin-ferritin conjugate are described and the specificity of cytochemical reactions are demonstrated. Furthermore experiments by immuno freeze-etching are reported for topological analysis of the lectin receptors.
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PMID:Electron microscopic demonstration of cell surface carbohydrates by means of peroxidase and ferritin complexes of the Lens culinaris lection. 115 Apr 86

The antineoplastic substances isolated from Chamaenerium angustifolium, Chanerol, a macromolecular polyphenol, and its complex with polysaccharide, Chanerozan, have been studied in vitro in tests of haemagglutination, tumor cell agglutination, leucoagglutination and some others. The results obtained show Chanerol as a new phytohaemagglutinin (lectin) which has no group specificity for human erythrocytes (ABO system). As distinct from other lectins (proteins) Chanerol belongs to another chemical class (macromolecular polyphenols) and has no effect on lymphocytes in leukoagglutination and blast transformation tests. Both preparations have been shown capable of agglutinating tumor cells in vitro and revealed antitumor activity in the intravenous and intraperitoneal administration to mice with transplanted tumors. The toxicity of Chanerozan and its titre of human and mouse erythrocyte agglutination are considerably lower than those of Chanerol. Thus, judging by haemagglutination test Chanerozan behaves as a typical complex of agglutinin with concurrent sugar.
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PMID:Macromolecular antitumor agents from Chamaenerium angustifolium. 115 36

Ultracytochemical visualization of specific carbohydrate receptors by means of lectins can provide valuable topological information about the functional status of cell surfaces in normal and transformed cells. In addition to the concanavalin A (Con A) rection and precoupling of lectin--peroxidase (PO) a new method is suggested using precoupling of the marker enzyme (PO) with an appropriated glycoprotein (glycopeptide) containing a lectin-specific carbohydrate. Furthermore, quantitative estimations of Con A reaction by means of automatic umage analysis are performed on peritoneal macrophages which point out a cluster formation, but give no hints for a loss of glycocalyx during the preparation process contrary to tumor cells.
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PMID:Methodological approaches to the study of carbohydrate surface receptore on macrophages and tumor cells. 116 Nov 11

Effect of various metabolic inhibitors on the agglutination of rat ascites tumor cells mediated by concanavalin A and Ricinus communis agglutinin was studied using a quantitative assay method for agglutination in which turbidity of cell suspension is measured. Cell agglutination was inhibited by low temperature, cytochalasin B and inhibitors of energy generating systems without affecting lectin binding, and agglutination was not affected by hydroxyurea, actinomycin D or cycloheximide. The inhibitors of energy generating systems decreased the cellular ATP level and inhibited macromolecular synthesis under the conditions where they inhibited the agglutinations. In contrast, cytochalasin B did not depress the cellular ATP level nor inhibit RNA and protein syntheses. These results suggest that the agglutination is associated with cellular energy dependent processes other than macromolecular synthesis; probably with some cellular surface movements participated by microfilament activity.
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PMID:Cellular energy dependent agglutination of rat ascites tumor cells mediated by concanavalin A and Ricinus communis agglutinin. 120 Dec 83

Qualitative and quantitative changes in nuclear DNA and phenotypic expression of human malignant skin tumors were examined during the course of progression. The numerical abnormalities of chromosomes demonstrated by interphase cytogenetics using the chromosome-specific in situ hybridization technique, were also used to reveal qualitative DNA changes in malignant tumor cells. For the analysis of the quantitative changes in nuclear DNA, fluorescence cytophotometry was used on the DAPI-stained tumor cells isolated from the paraffin-embedded sections. To survey abnormal gene expression in malignant tumor cells, lectin histochemistry for different sugar residues, immunohistochemical staining of HLA-DR, and in situ hybridization for H-ras, c-myc, N-myc or v-fos were used. The results showed that: 1) in one case of squamous cell carcinoma with invasion, the number of chromosomal abnormalities was much greater in the invasive than in non-invasive parts, with marked topographical heterogeneities; 2) the DNA-ploidies were largely shifted to the higher side with aneuploid stem-lines and polyploid cells in the invasive parts of all malignant tumors; 3) the expression of HLA-DR was induced at the invasive fronts of malignant melanomas; 4) the GS-I specific sugar residue(D-galactose) appeared in all extra-mammary Paget's cells; and 5) expression of "oncogenes" was found in about 60% of all malignant tumors examined. Thus, the progression of malignancy is accompanied by both qualitative and quantitative changes in nuclear DNA, resulting in abnormal gene expression.
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PMID:Qualitative and quantitative changes in nuclear DNA and phenotypic gene expression in human malignant skin tumors during their progression. 128 Oct 11


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