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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experiments were started with an animal model: Tumor antigens could be solubilized from fibrosarcomas of inbred guinea pigs by extraction with physiological saline. Extracts were fractionated by ammoniumsulfate precipitation, gel filtration, ion exchange chromatography, and polyacrylamide electrophoresis. Skin tests and leucocyte migration assays could detect antigenic activity in a number of fractions different with respect to size and charge. A less heterogeneous antigen could be extracted with phenol-water from guinea pig fibrosarcomas. Tumor associated antigens could be demonstrated in phenol-water extracts of human melanoma by leucocyte migration tests. Weak migration reactions were found with leucocytes from melanoma patients, not with leucocytes from controls. The frequency of positive results was similar in patients with and without metastases. No antibodies against antigens of phenol-water extracts could be detected in sera from melanoma patients. No antibodies against tumor associated substances could be demonstrated after immunization of rabbits with phenol-water extracts. Antigens extracted by phenol-water seem to be weak immunogens. Radioactive antigens were extracted from membranes of labelled cell cultures of human melanoma. Antigenic activity was assayed by double immune precipitation followed by sodium-dodecylsulfate-polyacrylamide-electrophoresis. Yields from available cell quantities were too small for further purification and clinical studies.
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PMID:[Isolation of soluble tumor-associated antigens of human malignant melanoma]. 68 Jun 24

The cell-surface proteins of 6 different melanoma cell cultures have been labelled with 125I using lactaperoxidase-catalysed iodination. Fractionation of the proteins was achieved using 5--22.5% polacrylamide-gradient gel electrophoresis in the presence of sodium dodecyl sulphate (SDS) and the proteins were detected by autoradiography. Up to 24 labelled proteins were detected in the individual cell cultures, but the proteins labelled differed considerably in the 6 cultures examined. A possible reason for this, involving variation in the glycosylation of cell-surface glycoproteins is discussed. Cells of the same melanoma line had similar cell-surface proteins at different passage levels, but changes in the labelled proteins occurred when the culture conditions were altered. The cell-surface proteins of high molecular weight were cleaved by trypsin, but most of the low mol.-wt. proteins were resistant to trypsin. The "large external transformation sensitive" (LETS) protein detected as a major protein on fibroblasts in culture was not a dominant protein on the melanoma cells. It was detected on only 4/6 cell cultures. Possible relationships of the cell-surface proteins described in this study to morphology, immunological properties and proteolytic activity of human melanoma cells are discussed.
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PMID:Lactoperoxidase-catalysed iodination of surface proteins on human melanoma cells. 68 8

Several molecular weight forms of plasminogen activator (PA) activity have been observed in serum-free conditioned media from human cells in culture. An antibody inhibition technique is described which combines inhibition of enzyme activity by anti-urokinase IgG with sodium dodecyl sulfate-gel electrophoresis to determine whether different molecular weight forms of human cell PA's are immunologically related to urokinase. Plasminogen activator forms with molecular weights of 85,000 to 95,000, 50,000 to 60,000, and 36,000 were inhibited by anti-urokinase IgG. In contrast, PA forms with molecular weights in the 73,000 range from three different types of human cells were not inhibited by comparable concentrations of the antibody. Human embryonic kidney cultures contain only anti-urokinase IgG-inhibitable PA forms, while melanoma-derived Malme-3M cultures contain only anti-urokinase IgG-resistant forms. Cultures of tumorigenic Detroit 562 cells and nontumorigenic IMR-90 cells contain a mixture of "antibody-sensitive" and "antibody-resistant" PA forms. The antibody-resistant 73,000-dalton PA form may be a precursor of the smaller antibody-sensitive, urokinase-related forms, or it may be the product of a second plasminogen activator gene which codes for a protein immunologically and structurally different from urokinase.
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PMID:Immunological characterization of multiple weight forms of human cell plasminogen activators. 76 81

The kinetics and properties of the activation of adenylate cyclase by cholera enterotoxin have been examined primarily in toad erythrocytes, but also in avian erythrocytes, rat fat cells and cultured melanoma cells. When cholera toxin is incubated with intact cells it stimulates adenylate cyclase activity, as measured in the subsequently isolated plasma membranes, according to a triphasic time course. This consists of a true lag period of about 30 min, followed by a stage of exponentially increasing adenylate cyclase activity which continues for 110 to 130 min, and finally a period of slow activation which may extend as long as 30 hr in cultured melanoma cells. The progressive activation of adenylate cyclase activity by cholera toxin is interrupted by cell lysis; continued incubation of the isolated membranes under nearly identical conditions does not lead to further activation of the enzyme. The delay in the action of the toxin is not grossly dependent of the number of toxin-receptor (GM1 ganglioside) complexes, and is still seen upon adding a second dose of toxin to partially stimulated cells. Direct measurements indicate negligible intracellular levels of biologically active radioiodinated toxin in either a soluble or a nuclear-bound form. The effects are not prevented by Actinomycin D (20 mug/ml), uromycin (30 mug/ml), cycloheximide (30 mug/ml), sodium fluoride (10 mM) or sodium azide (1 mM); KCN, however, almost completely prevents the action of cholera toxin. The action of the toxin is temperature dependent, occurring at very slow or negligible rates below certain critical temperatures, the values of which depend on the specific animal species. Thetransition for toad erythrocytes occurs at 15 to 17 degrees C, while rat adipocytes and turkey erythrocytes demonstrate a discontinuity at 26 to 30 degrees C. The temperature effects are evident during the lag period as well as during the exponential phase of activation. The rate of decay of the stimulated adenylate cyclase activity of cultured melanoma cells indicates a half-time of about 36 hr. The rate of exponentially increasing activity and extent of enzyme activation are related to the number of bound toxin molecules according to a Langmuir adsorption isotherm and are half-maximal when about 2000 molecules of toxin are bound per cell. It is proposed that initially cholera toxin binds ineffectively, but that it is converted to an active form during the lag phase. This process may involve lateral motion of toxin-GM1 ganglioside complex within the plane of the membrane. The kinetics of adenylate cyclase activation are consistent with the possibility that during the exponential phase a bimolecular association is proceeding between the active form of the cholera toxin and some other membrane component. The possibility is considered that the cholera toxin molecule may bind directly to adenylate cyclase. These considerations may prove useful in understanding the possible interactions of active hormone-receptor complexes with adenylate cyclase in cell membranes.
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PMID:Mechanism of activation of adenylate cyclase by Vibrio cholerae enterotoxin. 80 48

Yeast phenylalanine ammonia-lyase (EC 4.3.1.5) catalyzes the deamination of L-phenylalanine to form trans-cinnamic acid and tyrosine to trans-coumaric acid. Maximal enzyme activity in Rhodotorula glutinis (2 units/g, wet weight, of yeast) was induced in late-log phase (12 to 14 hours) of growth in a culture medium containing 1.0% malt extract, 0.1% yeast extract, and 0.1% L-phenylalanine. A highly purified enzyme was obtained by fractionation with ammonium sulfate and sodium citrate followed by chromatography on DEAE-cellulose and Sephadex G-200. The active preparation yielded a major component on three different polyacrylamide gel electrophoretic systems. Antisera to phenylalanine ammonia-lyase was raised in rabbits and detected by double immunodiffusion. The antigen-antibody complex was enzymatically active in vitro. The biological half-life of the enzyme was approximately 21 hours in several mammalian species (mice without and with BW10232 adenocarcinoma and B16 melanoma, rats, and monkeys) after a single injection; however, upon repeated administration, phenylalanine ammonia-lyase had a much shorter biological half-life. The onset of rapid clearance occurred earlier in tumor-bearing than in nontumor-bearing mice indicating a direct or indirect influence by the tumor on the biological half-life of phenylalanine ammonia-lyase.
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PMID:Phenylalanine ammonia-lyase. Induction and purification from yeast and clearance in mammals. 98 16

Tyrosine phenol-lyase from Erwinia herbicola was purified with the goal of assessing its effect on growth of malignant melanoma. Ammonium sulfate-sodium citrate fractionation and diethylaminoethyl cellulose-hydroxylapatite chromatography were used. The purified enzyme was shown to reduce plasma tyrosine levels when administered to normal C57BL x DBA/2 F1 mice. The plasma half-life value of the enzyme was found to be 6 to 7 hr. Unlike results reported with glutaminase and asparaginase preparations, the lactate dehydrogenase-elevating virus had no significant influence on plasma clearance of tyrosine phenol-lyase. The enzyme significantly inhibited growth of established B-16 melanoma tumors.
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PMID:Some biological properties and an in vivo evaluation of tyrosine phenol-lyase on growth of B-16 melanoma. 124 96

Studies of peculiarities of acetylation with the use of sulfadimidine showed the distribution of female white non-bred mice into two groups - with high and low activity. In C3H/He mice a relatively high activity of sulfadimidine acetylation was observed, while in C57BL/He mice a low activity of acetylation was noted. The growth of transplanted melanoma B-16 in C57BL/He mice and sarcoma 37 and sarcoma 180 in non-bred mice resulted in an increased activity of sulfadimidine acetylation. The use of w-sodium methylpantothenate (an antagonist of pantothenic acid) failed to show an increased activity of sulfadimidine acetylation and inhibited the tumor growth.
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PMID:[Acetylation reaction in mice in the normal state and in tumors]. 127 65

Human melanoma cells (MM96E) were incubated with a phenotypic modifier (L-ethionine) to compare its effects on phenotypic expression with those induced by sodium butyrate and dimethyl sulfoxide. In contrast to the latter agents, L-ethionine (8mM) failed to arrest the cell cycle at the G1 phase or to inhibit colony formation ability after 48 hr incubation. Tyrosinase activity changed in parallel with 5-S-cysteinyldopa (5-S-CD) content during treatment with sodium butyrate or dimethyl sulfoxide. Tyrosinase was inhibited in L-ethionine-treated cells, probably because of metabolism of L-ethionine to sulfhydryl compounds; this remains to be clarified. Gamma-glutamyl transpeptidase activity changed inversely with tyrosinase activity after sodium butyrate or dimethyl sulfoxide incubation, whereas L-ethionine did not significantly alter the enzyme activity. In addition, only sodium butyrate induced alkaline phosphatase activity. L-ethionine was less effective than sodium butyrate or dimethyl sulfoxide in inhibiting expression of the B8G3 melanosomal antigen, as determined by Western blotting. These results suggest that phenotypic modifiers (differentiation inducers) affect melanoma cells in various ways and that melanogenesis therefore reflects only one aspect of differentiation in pigment cells.
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PMID:Alteration of melanoma melanogenesis by phenotypic modifiers. 136 29

Here we describe a two-step procedure for purification of human tenascin from conditioned medium of the SK-MEL-28 human melanoma cell line. The first step consists in passing the conditioned media through two chromatography columns connected in sequence. The first is a large capacity gelatin--Sepharose affinity chromatography column (to remove fibronectin), the second, over which the unbound material from the first column flows directly, is a hydroxyapatite chromatography column. Under these conditions, all tenascin present in the conditioned medium binds to the hydroxyapatite chromatography column from which it is then eluted by a 5-300 mM sodium phosphate gradient. With this step, we obtain a crude tenascin preparation, concentrated about 20 times with respect to the starting conditioned medium, and in which tenascin represents more than 50% of the total protein. The second step consists of two sequential precipitations with 6% and 12.8% poly(ethylene glycol). After this step, tenascin is more than 95% pure and does not show any contamination of chondroitin-sulfate-containing proteoglycans that are known to bind to it. From 21 medium we obtain about 3-4 mg tenascin which corresponds to a yield of about 40-50%. This procedure gives a higher yield, is simpler with respect to procedures previously described, avoids the exposure of the protein to denaturing agents or harsh conditions and could be used for purification of tenascin from the conditioned media of other cell lines. Thus, this procedure may represent a simple and useful tool for the preparation of tenascin to study its biological functions.
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PMID:A simple procedure for tenascin purification. 137 29

An essential element in the development of effective vaccines against human malignant melanoma is the identification of antigens which are relevant for vaccine construction as evidenced by their ability to stimulate antimelanoma immune responses in humans. In this study, we identified immunogenic melanoma antigens using as probes antibodies induced in patients immunized with a vaccine which contains a broad range of potential immunogens. By immunoprecipitation/sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of detergent lysates of radioiodinated melanoma cells, we found that 17 (65%) of 26 patients sequentially immunized with a polyvalent melanoma antigen vaccine developed antibodies to one or more melanoma cell surface antigens with approximate molecular weights of 38,000-43,000, 75,000, 110,000, 150,000, and 210,000. The immunodominant antigens which most frequently stimulated antibody responses were the M(r) 110,000 antigen followed by the M(r) 210,000 and 38,000-43,000 antigens, which induced antibody responses in 62%, 27%, and 19% of patients, respectively. These three antigens were commonly expressed on different melanomas but rarely on nonmelanoma cells and are unrelated to class I or II human leukocyte antigens or to the previously described p97 or M(r) 240,000 proteoglycan melanoma-associated antigens. Thus, these three antigens are attractive candidates for the construction of melanoma vaccines, because they are immunogenic in humans and are preferentially expressed on melanomas.
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PMID:Identification of immunogenic human melanoma antigens in a polyvalent melanoma vaccine. 138 48


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