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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endogenous carbohydrate-binding proteins (lectins) were detected in specimens of tumor tissue (undifferentiated carcinoma and xenografted small-cell carcinoma) from human lung. Fractionation of salt and detergent extracts on different sets of Sepharose columns covalently derivatized with lactose, asialofetuin, melibiose, mannan, and fucose, successive elution with a chelating agent and a specific sugar, and analysis of the eluates by gel electrophoresis, resulted in the characterization of the profiles of endogenous carbohydrate-binding proteins. All preparations were devoid of enzymatic activity. Comparison between the patterns of the two types of lung carcinoma showed significant qualitative differences, e.g. the presence of fucose-binding proteins of apparent molecular weights 60,000 and 80,000 in the undifferentiated carcinoma, and the presence of beta-galactoside-binding proteins of apparent molecular weights 18,000 and 22,000 in the small-cell lung carcinoma. These proteins were not detectable in normal lung tissue. Such differences, documented for the first time for human lung tumors, are of potential importance as a step towards a lectin-based refinement of lung-cancer diagnosis and therapy.
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PMID:Expression of endogenous lectins in human small-cell carcinoma and undifferentiated carcinoma of the lung. 304 Feb 51

A UDP-Gal:N-acetyllactosaminide alpha (1,3)-galactosyltransferase from Ehrlich ascites tumor cells has been purified over 200,000-fold to apparent electrophoretic homogeneity. The purified enzyme transfers D-galactosyl groups from UDP-Gal to beta-D-Gal-(1,4)-D-GlcNAc in alpha-linkage. The apparent Km values for donor and acceptor substrates are 12.6 microM and 1.15 mM, respectively. The trisaccharides beta-D-Gal(1,4)-beta-D-GlcNAc(1,2)- or (1,6)-D-Man exhibit a Km 5-fold lower than that of N-acetyllactosamine, and an even more pronounced effect is observed with the biantennary pentasaccharide beta-D-Gal(1,4)-beta-D-GlcNAc(1,2)-[beta-D-Gal(1, 4)-beta-D-GlcNAc-(1,6)]-D-Man (Km 0.10 mM). The transferase shows a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions with an apparent subunit molecular weight of 80,000, exhibits a pH optimum at 6.2, and requires Mn2+ ions and detergent for enzymatic activity. Specificity studies using immobilized oligosaccharides show that the minimum acceptor structure for the alpha-galactosyltransferase is N-acetyllactosamine. The narrow specificity of the alpha-galactosyltransferase is indicated by the fact that lactose, beta-D-Gal(1,3)-D-GlcNAc, and beta-D-Gal(1,4)-[alpha-L-Fuc(1,3)]-D-GlcNAc are very poor acceptors. The enzyme differs from the blood-group B-specified galactosyltransferase in that the sequence alpha-L-Fuc(1,2)-beta-D-Gal(1,4)-D-GlcNAc is not an acceptor. Oligosaccharides, glycoproteins, glycolipids, and glycosaminoglycans containing the terminal nonreducing N-acetyllactosamine unit all serve as acceptors for the enzyme.
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PMID:Purification and characterization of a UDP-Gal:beta-D-Gal(1,4)-D-GlcNAc alpha(1,3)-galactosyltransferase from Ehrlich ascites tumor cells. 308 77

By altering the receptor binding specificity of the highly potent natural toxin ricin, a macrophage specific immunotoxin was developed. Ricin ordinarily does not demonstrate cell type specificity and is capable of binding and entering cells through galactose containing receptors resulting in rapid cell death. A murine anti-rat peritoneal macrophage IgGl monoclonal antibody, B-6, was developed to serve as a target specific carrier for ricin. By covalently binding monoclonal antibody B-6 and reversibly binding lactose to ricin, a new biologically active hybrid toxin possessing macrophage specificity was developed. When P3X63-Ag8.653 myeloma cells, which served as an nonspecific target cell type, and macrophages were treated with the ricin conjugate over a broad range of concentrations and various time periods, the conjugate demonstrated substantially greater toxicity toward macrophages than myeloma cells even though both cell types responded similarly to treatments with unconjugated ricin. It was also observed that ricin was considerably more toxic to macrophages when conjugated to monoclonal antibody B-6 than unconjugated ricin. Through ricin-antibody conjugation a high degree of specificity and toxicity can be attained potentially suitable for anti-tumor reagents and immuno-modulators.
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PMID:Target ricin by coupling to an anti-macrophage monoclonal antibody. 308 61

The use of tumor immunotherapy using whole ricin-antibody conjugates is complicated by the nonspecific lectin activity of the ricin B-chain which leads to toxic side effects. A novel method of coupling whole intact ricin to monoclonal antibody (MoAb) is described herein, where the nonspecific binding of the ricin B-chain is blocked. The coupling was done using the bifunctional reagents S-acetylmercaptosuccinic anhydride for antibody and succinimidyl 3-(2-pyridyldithio)propionate for ricin, and this resulted in the loss of B-chain binding activity, while impairing neither the toxic potential of the A-chain nor the activity of the MoAb. The purified immunotoxins could not bind to lactose-Sepharose and were equally cytotoxic in vitro to MoAb-reactive cell lines in the presence or absence of lactose. The coupling method was suitable for six different ricin-antibody conjugates and also using ricin deglycosylated by treatment with periodate. However, the blocking of the ricin B-chain was only effective with whole IgG molecules as F(ab')2-ricin immunotoxins could, like ricin, bind to lactose-Sepharose. Ricin-antibody conjugates reduced the [3H]leucine incorporation of appropriate target cells by 50% at a concentration of 6 to 45 ng/ml, whereas nonreactive antibody immunotoxins were not toxic to the target cells at concentrations as high as 10(4) ng/ml. The specific cytotoxicity of these immunotoxins could be inhibited by the addition of unconjugated reactive MoAb; the presence of lactose or a nonreactive MoAb did not significantly affect the observed cytotoxicity. Thus, whole ricin-antibody conjugates produced in this way do not bind nonspecifically to target cells, the most important implication being that such immunotoxins should be more potent that ricin A-chain conjugates and capable of being used in vivo.
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PMID:Novel synthesis and in vitro characterization of disulfide-linked ricin-monoclonal antibody conjugates devoid of galactose binding activity. 326 Aug 14

As described previously (I. Kijima-Suda et al., Cancer Res., 46: 858-862, 1986), a sialyltransferase inhibitor, 5-fluoro-2',3'-isopropylidene-5'-O-(4-N-acetyl-2,4-dideoxy-3,6,7,8-tetra -O- acetyl-1-methoxycarbonyl-D-glycero-alpha-D-galactooctapyranosyl)ur idine (KI-8110), inhibits pulmonary metastasis of murine colon adenocarcinoma 26 sublines of high (NL-17) and low (NL-44) metastatic potential. To investigate the mechanism of this inhibition, the effect of KI-8110 on the metastatic cascade, especially on the interaction between tumor cells and platelets which may play a crucial role in tumor cell metastasis, was examined. NL-17 cells induced irreversible platelet aggregation in heparinized human platelet-rich plasma in vitro. This activity was reduced by pretreatment of the tumor cells with KI-8110. Inhibition of aggregation was also induced by the treatment of tumor cells with neuraminidase or Limax flavus agglutinin, a lectin specific for sialic acid. Sialic acid, fucose, sialyllactose, and bovine submaxillary mucin inhibited this tumor cell-induced platelet aggregation, while galactose, mannose, lactose, alpha 1-acid glycoprotein, fetuin, and asialo-bovine submaxillary mucin did not. KI-8110 also inhibited platelet-derived growth factor-dependent growth of NL-17 cells, but showed no effect on insulin or epidermal growth factor-dependent growth of the tumor cells. Platelet-derived growth factor-induced phosphorylation of membrane protein was reduced by treatment of NL-17 cells with KI-8110. The same result was obtained in the neuraminidase-treated membrane fraction of NL-17 cells. These results suggest that KI-8110 inhibits experimental tumor cell metastasis by inhibiting the interaction between tumor cells and host platelets in at least two pathways, and this may be due to a reduction of sialic acid contents of the membrane surface of tumor cells.
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PMID:Possible mechanism of inhibition of experimental pulmonary metastasis of mouse colon adenocarcinoma 26 sublines by a sialic acid: nucleoside conjugate. 328 33

The therapeutic efficacy of whole ricin, or recombinant ricin A chain, coupled to a monoclonal antibody that reacts with the idiotype of the surface IgM expressed on guinea pig L2C lymphoblasts, was assessed. In vitro studies were done to characterize the immunotoxins (IT) and to demonstrate their specificity before use in vivo. The concentration of whole ricin IT (M6-Ricin) that inhibited protein synthesis by 50% (IC50) in L2C cells was 1.4 X 10(-9) M, in a 5-hr assay, in the presence of lactose to block non-antibody-directed toxicity. M6-Ricin did not inhibit protein synthesis in two control guinea pig cell lines that did not express the idiotype, nor did a whole ricin IT prepared with an isotype-matched monoclonal antibody of irrelevant specificity inhibit protein synthesis in L2C cells. Two recombinant ricin A chain IT, which differed from one another by a factor of 2 to 3 in the number of A chains conjugated per antibody molecule, were less effective in vitro than M6-Ricin (IC50 of greater than 5 X 10(-8) M). For in vivo experiments, the IT were given by the i.p. route 24 hr after the i.p. inoculation of 1 X 10(5) L2C cells. The highest doses of M6-Ricin and M6-Ricin A chain IT tested, 30 micrograms/kg and 3000 micrograms/kg, respectively, were within fourfold to fivefold of their maximum tolerated doses; no deaths or ill effects due to ricin toxicity were noted. These doses increased the median survival time of L2C-bearing guinea pigs to 31 to 34 days, compared with 15 days for untreated animals. This magnitude of increase in survival indicates that 99.999% (5 logs) of injected tumor cells were eliminated, thus accounting for the 12% long-term survival rate obtained. Median survival times for guinea pigs treated with 30 micrograms/kg of the A chain IT were 18 and 21 days for the two conjugates tested, and the median survival for guinea pigs treated with 3000 micrograms/kg of unconjugated antibody was 18 days. Our data demonstrate that recombinant A chain IT are active in vivo and that the B chain of ricin can potentiate IT activity in vivo. Although the potency differs by 100-fold, the therapeutic index of the intact ricin IT is similar to that of the ricin A chain IT.
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PMID:Whole ricin and recombinant ricin A chain idiotype-specific immunotoxins for therapy of the guinea pig L2C B cell leukemia. 349 93

We have synthesized a reagent for antibody directed cell targeting composed of the monoclonal antibody (MoAb) T101 linked to the potent toxin ricin. The immunotoxin (IT) was subsequently radiolabeled by a cyclic anhydride procedure with 90Yttrium (90Y) to construct a radioimmunotoxin (RIT) that may have potential for cancer therapy. We evaluated the reagent for selectivity in binding and protein synthesis inhibition (PSI) assays. The RIT selectively bound antigen positive leukemia T-cell lines, with minimal binding to antigen negative control lines. The IT inhibited 87% or greater protein synthesis activity at 1 microgram/ml and exhibited an IC50 (the dose inhibiting 50% activity) of 0.18 +/- 0.08 microgram/ml in the presence of lactose. RIT and nonlabeled IT showed comparable degrees of PSI at 1 microgram/ml and 10 micrograms/ml, suggesting that labeling had little overall effect on the activity of the immunoconjugate. However, indirect evidence showed that the galactose binding site of ricin was inhibited 10-fold by its exposure to 90Y. Control RIT were minimally inhibitory. IT labeled with 131Iodine (131I) by an iodine monochloride technique also retained its capability to selectively inhibit protein synthesis. When RIT were tested for potency in a clonogenic assay against human leukemia T-cell lines, they inhibited 3.61 logs of tumor cell growth at 10 micrograms/ml. This did not represent an improvement over the log elimination with radiolabeled antibody alone, which showed 4.19 log elimination of tumor cells. Our observation that the 90Y-labeled RIT and labeled antibody can selectively eliminate about four logs of tumor cells in an in vitro clonogenic assay is unique. The ability of RIT to kill several logs of tumor cells in vitro renders RIT interesting anti-tumor reagents.
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PMID:Human leukemia cell binding and killing by anti-CD5 radioimmunotoxins. 349 27

Flow cytofluorometry and drug targeting with labelled neoglycoproteins are used as tools to probe for membrane lectins in two human adenocarcinoma cell lines. Both cell lines express activities for galactosides, glucosides and fucosides. Affinity chromatography on gels with immobilized sugar leads to purification of an alpha-galactoside-binding protein at an apparent molecular weight of 64 kDa that also binds to lactose, maltose and fucose and exhibits Ca2+-requirement for binding, a beta-galactoside-binding protein without Ca2+-requirement at an apparent molecular weight of 14 kDa, and an alpha-glucosyl-binding protein without Ca2+-requirement at an apparent molecular weight of 34 kDa from both cell lines. The description of membrane lectins, documented here for the first human tumor cell lines, is an initial step towards a lectin-based improvement of the clinical management of human colon adenocarcinoma.
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PMID:Characterization of membrane lectins in human colon carcinoma cells by flow cytofluorometry, drug targeting and affinity chromatography. 356 77

The carcinogenic potential of tilidine fumarate, a synthetic analgesic, was studied for 80 and 104 weeks in mice and rats, respectively. Groups of 50 albino CF1 mice and 65 albino Wistar rats of each sex received tilidine fumarate-lactose blend (1:1) at doses of 100, 40 and 16 mg/kg. The control groups consisted of 100 mice and 115 rats of each sex and received the lactose vehicle only. Treatment-related non-neoplastic changes consisted of reversible, increased cytoplasmic eosinophilia of hepatocytes in high and mid dose rats corresponding to areas of proliferating smooth endoplasmic reticulum; and an increased incidence in high dose rats of proliferative or cystic lesions of the biliary epithelium. Adequate survival rates allowed stringent statistical analysis of neoplasia. Tilidine did not evoke increased tumor incidences or changes in the average latency or onset of tumors in either species. The most frequent tumors represented spontaneous neoplasia characteristic of historical background incidence in these strains. In mice, the only statistically significant (P less than 0.01) variation in tumor incidence was an increased rate of lung alveologenic adenocarcinomas in females at 100 mg/kg (24%), compared with the concurrent untreated controls (10%), but without a statistically significant difference from historical control data (27%). Female rats given 100 mg/kg showed statistically significant (P less than 0.01) decreased incidences of mammary fibroadenoma and pituitary adenoma. From these data, it was concluded that the synthetic analgesic tilidine does not possess tumorigenic potential in rodents.
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PMID:Evaluation of chronic toxicity and carcinogenesis in rodents with the synthetic analgesic, tilidine fumarate. 370 81

Altogether 124 patients were followed up for disseminated breast cancer (82) and hematosarcoma (42). The patients were divided into two groups: the main group was given 500 ml of 20% protein or low-lactose enteral feeding in addition to the hospital diet; the control group received only the hospital diet. Chemotherapy lasted 3 weeks. The patients on chemotherapy received enteral feeding every day throughout the entire treatment period. In the course of treatment, the patients were examined for blood characteristics, size of the tumor and affected lymph nodes, body weight, major metabolism, protein metabolism, vitamin metabolism, osmotic and peroxide resistance of red cells, and liver function. The research program covered more than 150 characteristics. The data obtained were processed by computer. It has been disclosed that inclusion of protein and low-lactose enteral feeding into the diet of cancer patients improves the alimentary status, decreases the leukopenia and thrombocytopenia incidence. It is advisable that specialized milk concentrates (enteral feeding) should be included into the diet of cancer patients as a necessary component of a complex of therapeutic measures used during chemotherapy.
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PMID:[Prophylactic effect of enteral feeding preparations during the chemotherapy of oncology patients]. 392 Aug 27


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