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

Three distinct dissemination-related phenotypes have been distinguished among cell subpopulations of the mouse B16 melanoma: tumorigenicity, spontaneous metastasis from subcutaneous tumors, and organ colonization following intravenous injection of cells. From a progenitor clone (G3) of tumorigenic but nonmetastatic and noncolonizing (null) cells that underwent phenotypic diversification in vitro and in vivo, 4 subclones were obtained: G3.5 (culture-generated metastatic), G3.12 (tumor-generated metastatic), G3.15 (culture-generated null), and G3.26 (tumor-generated colonizing). The growth potentials of the parent clone and derived subclones were investigated comparatively in in vivo assays (tumorigenicity, tumor growth rate, and lung colonization potential), monolayer culture assays (generation time, saturation density, clonogenicity, and rate of detachment by trypsin), and in soft agar. In overall growth potential, G3.26 greater than G3.12 greater than G3, G3.5 greater than G3.15. These results indicate that metastatic populations of the B16 melanoma are not the most rapidly and effectively growing cells obtainable from that tumor.
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PMID:Growth characteristics of clonal cell populations constituting a B16 melanoma metastasis model system. 388 9

To investigate whether the cell dispersion techniques commonly employed to harvest monolayer cultures of tumor cells for injection into experimental animals might induce alterations in cellular biochemistry, we compared the phosphoprotein profiles of 6 B16 melanoma clones of distinct metastatic potential using 2-D gel electrophoresis after growth in monolayer culture, after suspension by treatment, with trypsin/EDTA and after injection of suspended cells into syngeneic mouse plasma. Trypsin/EDTA treatment and subsequent exposure to syngeneic mouse plasma induced significant alterations in phosphoprotein composition in all clones. Most alterations were quantitative, involving either enhanced or diminished expression of specific phosphoproteins, but qualitative changes involving expression of novel phosphoproteins were also observed. None of the changes in phosphoprotein composition correlated with metastatic potential. The principle alteration induced in all clones by trypsin/EDTA involved enhanced phosphorylation of an NP-40-soluble component with a molecular weight of 79,000 and an isoelectric point of 6.3 [pp79 (6.3)]. This determinant was detected in extracts of B16 monolayer cultures but its level of phosphorylation was enhanced significantly by trypsin/EDTA treatment and by exposure of the harvested cells to syngeneic mouse plasma. These data indicate that procedures commonly employed to harvest tumor cells for assay of tumorigenic and metastatic potential may provide extensive alterations in phosphoprotein composition and that biochemical investigations of tumor cells grown in monolayer culture may not accurately reflect the metabolic status of the same cells immediately prior to and following i.v. injection into experimental animals.
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PMID:Alterations in the phosphoprotein composition of tumor cell clones induced by cell culture techniques used routinely in assessing metastatic behavior in vivo. 391 47

Cysteine protease inhibitors that specifically reacted with several cysteine proteases were found in KSCN extract of human melanoma tissue. From 30 gm of the tissue, approximately 593.5 U inhibitor was obtained. The inhibitors were adsorbed on a papain-Sepharose column and could be eluted with 10 mmol/L phosphate buffer, pH 6.0, containing NaCl or KCl, or with 20 mmol/L acetate buffer, pH 4.0, containing KSCN. They revealed a strong inhibitory activity for cysteine proteases such as ficin, papain, and cathepsin B, but did not react with cysteine protease bromelain or serine protease trypsin. No immunologic relationship was confirmed between the inhibitor and other well-known plasma inhibitors such as alpha 1-antitrypsin, alpha 2-macroglobulin, alpha 1-antichymotrypsin, antithrombin III, C1-in-activator, and alpha 2-plasmin inhibitor. With Sephadex G-100, two main peaks of molecular weight 40,000 and 10,000 were detected in the KSCN extract of the human melanoma tissue. However, the inhibitors revealed three molecular weights of 10,000, 25,000, and 80,000 when estimated by Sephadex G-100 gel filtration after papain-Sepharose affinity chromatography. On the other hand, the molecular weights of the inhibitors changed to two peaks of 25,000 and 10,000 on rechromatography with a papain-Sepharose column.
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PMID:Cysteine protease inhibitors isolated from human malignant melanoma tissue. 393 99

Comparative quantitative data are presented concerning the adhesion, proliferation and invasive behaviour of RPMI-3460 melanoma cells on (1) plain collagen gels, (2) monolayer cultures of fibroblasts and endothelial cells growing on the gel surface, and (3) the exposed endothelial and fibroblast extracellular matrices (ECMs). Both types of ECMs enhanced melanoma cell adhesion and proliferation (compared with plain gels) and had marked, but distinctive, effects on melanoma morphology. The thickness and composition of the ECMs was altered by treatment of the matrices with enzymes (trypsin, elastase and chondroitinase ABC) or by using ECMs produced by endothelial cells at various times after confluence. Variations in the thickness and composition of the ECMs had no effect on the behaviour of melanoma cells growing on these matrices; our results suggest that the glycoproteins and glycosaminoglycan ECM constituents removed by digestion with the enzymes do not play an important role in melanoma cell attachment, proliferation and migration. Melanoma cells plated on the surface of a plain collagen gel rapidly migrated down into the collagen matrix, with approximately 30% of the cells found within the gel after 6 days of incubation. Fibroblast and endothelial ECMs significantly and distinctively inhibited melanoma invasion into the underlying collagen gel. The extensive invasion of melanoma cells into the gel was not accompanied by hydrolysis of the collagen fibres. Conversely, fibroblast and endothelial ECMs, which acted as effective barriers, were extensively hydrolysed by the melanoma cells. The possible use of ECMs deposited on collagen in the study of melanoma local invasion (on fibroblast ECMs) and extravasation (on endothelial ECMs) is discussed.
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PMID:The interaction of melanoma cells with fibroblasts and endothelial cells in three-dimensional macromolecular matrices: a model for tumour cell invasion. 401 7

Glycosaminoglycan (GAG) synthesis of B-16 melanoma metastatic variants was examined in vivo and in vitro to begin to assess the relationship between the presence of these polymers and the process of primary invasion and metastasis. The variants that were examined for GAG production included the F-1 line that exhibits low metastatic potential, the F-10 line selected for high metastatic potential, and the BL6 line selected for high invasiveness. The F-1 cell line was routinely less invasive than the F-10 and BL6 lines when injected s.c. into the legs of irradiated Swiss Webster mice. All cell lines formed palpable tumors after s.c. injection, but histological sections revealed early and extensive invasion in only F-10 and BL6 tumors. The F-1 tumors were surrounded by a connective tissue capsule and did not begin to invade into host tissue until this structure disappeared approximately 16 days after injection of tumor cells. Some consistent alterations in GAG synthesis, particularly the release of hyaluronic acid and heparan sulfate, were observed among the cell lines in vivo and in vitro, although differences observed in vitro were small and variable. In vivo all tumors were surrounded by a hyaluronic acid-rich zone that was concentrated at the tumor-stromal interface and was transitory. Hyaluronate occurred as a diffuse band around BL6 and F-10 tumors but was confined to a capsule surrounding the less aggressive F-1 tumor. In vitro the BL6 and F-10 cell lines released larger amounts of heparan sulfate and hyaluronic acid than did the F-1 cell line. Differences in release of chondroitin sulfate by the cell lines were not observed. Differences in trypsin-releasable GAG, presumably associated with the glycocalyx, were also not apparent. These results link the release in vitro and organization in vivo of hyaluronic acid and heparan sulfate to invasion and metastasis.
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PMID:Glycosaminoglycan production by murine melanoma variants in vivo and in vitro. 402 88

Mouse peritoneal macrophages possess a specific plasma membrane receptor for antibody-coated particles. Sheep red cells coated with rabbit 7S antibody attach readily to the macrophage surface and are subsequently interiorized. The fusion of macrophage with nonphagocytic mouse melanoma cells produces heterokaryons in which the macrophage receptor is drastically altered. The receptor is present shortly after fusion and heterokaryons are actively phagocytic. The ability to bind and ingest red cells is, however, progressively lost over the next 12-24 hr and does not reappear thereafter. Exposure of heterokaryons to trypsin (1-100 microg/ml for 30 min at 37 degrees C) results in the reappearance of initial receptor activity and the unmasking of the surface receptor. This property is again lost upon subsequent cultivation. The masking process takes place when cells are cultivated in the absence of IgG so that the adsorption of antibody from the medium is not responsible for this phenomenon. Inhibition of heterokaryon protein synthesis preserves phagocytic activity in a reversible fashion and prevents the masking of macrophage receptors. Inhibition of melanoma RNA synthesis before fusion is also able to block subsequent masking, but is ineffective if delayed until after fusion. Ultraviolet irradiation of the melanoma cell before fusion prevents subsequent masking, whereas similar treatment of the macrophage has no effect. Cells differ markedly in their ability to mask the macrophage phagocytic receptor after fusion. Ehrlich ascites tumor cells mask the receptor rapidly, primary chick fibroblasts minimally, and embryonic chick erythrocytes not at all.
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PMID:Macrophage-melanoma cell heterokaryons. IV. Unmasking the macrophage-specific membrane receptor. 493 49

The aggregating properties of murine melanoma cell lines with low metastatic potential (B16-F1) and high metastatic potential (B16-F10 and B16-BL6) were compared. All three types of cells were found to possess Ca2+-dependent and Ca2+-independent intrinsic mechanisms for cell adhesion, though the extent of reaggregation varied in each mechanism. After trypsin treatment at around 1 microgram/ml, F10 and BL6 cells reaggregated in the presence of 1mM Ca2+ to a greater degree than F1 cells. F10 and BL6 cells were also more aggregative than F1 cells after dissociation with collagenase. The apparent adhesiveness of the cells was found to be dependent on both the manner of cell preparation for reaggregation and on the presence of external Ca2+ or serum factors. The results are discussed in relation to the mechanisms of tumor cell arrest with emphasis on the effect of extracellular factors on cell adhesiveness.
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PMID:Adhesive properties of weakly and highly metastatic melanoma cell lines. 608 47

Monoclonal antibodies were used to study p97, a human melanoma-associated antigen (MAA). Four hybridomas, designated 4.1, 96.5, 118.1, and 8.2, were obtained by fusing mouse myeloma cells with spleen cells from mice immunized with human melanoma cells. Antibodies 4.1 and 8.2 were IgG1; antibodies 96.5 and 118.1 were IgG2a. Sequential immunoprecipitation (IP) and sodium-dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that all 4 antibodies recognized the same 97 kilodalton (kD) protein. Binding studies with 125I-labeled antibody showed that antibodies 4.1 and 96.5 bound the same epitope, p97a. Antibodies 118.1 and 8.2 defined epitopes p97b and p97c, respectively. Six monoclonal antibodies (M17, L1, L10, R10, I12, and K5) specific for gp95, a kD melanoma cell surface glycoprotein were also tested. Sequential IP showed that these antibodies bound p97; p97 and gp95 are thus identical. Binding studies showed that antibody m17 bound epitope p971, and antibodies L1, L10, and R19 bound epitope p97c. Antibodies I12 and K5 defined 2 other epitopes, p97d and p97e, respectively. SDS-PAGE under nonreducing conditions indicated that p97 is monomeric, probably with intrachain disulfide bonds. Cell-surface labeling of sialic acid residues and neuraminidase digestion showed that p97 is a sialoglycoprotein. Digestion of p97 with papain or trypsin produced a stable 40 kD fragment, which expressed epitopes p971, p97b, and p97c, but not p97d or p97e.
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PMID:Structural characterization of human melanoma-associated antigen p97 with monoclonal antibodies. 616 74

Single-cell suspensions of several tumor cell lines, including five human melanomas (A375, SH4, Hs294, Hs852, and Hs939), a human cervical adenocarcinoma (HeLa-S3), a murine melanoma (B16-F1), and a murine fibrosarcoma (UV-2237P), undergo extensive homotypic aggregation in the presence of the glycoproteins fetuin and its desialated derivative, asialofetuin. This phenomenon was observed even at very low glycoprotein concentrations (less than 10 micrograms/ml). Fluorescent derivatives of fetuin and asialofetuin bind to the surface B16-F1 melanoma cells; this binding can be inhibited by lactose (0.1 M). Since the above results suggested the presence of a carbohydrate-binding component(s) on the tumor cells, we tested the possibility that the cells contain endogenous lectin(s). Extracts prepared from the neoplastic cell lines used in this study exhibited a potent capacity to agglutinate trypsin-treated, glutaraldehyde-fixed rabbit erythrocytes. This activity was abolished by treating the extracts with trypsin and could be inhibited by millimolar concentrations of lactose, whereas D-galactose, D-galactosamine, and N-acetyl-D-galactosamine were much less potent inhibitors. D-Mannose, L-fucose, and N-acetyl-D-glucosamine failed to inhibit hemagglutination at 0.2 M. These results demonstrate the presence of a galactoside-specific lectin in the tumor cells. The implications of the existence of a carbohydrate-binding protein(s) on the surface of malignant cells on their in vivo behavior, especially as it may relate to metastatic spread, are discussed.
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PMID:Lectin-like activities associated with human and murine neoplastic cells. 616 52

Intermediate-sized filaments have been noted in epithelioid sarcoma by previous investigators, two of whom have reported that the filaments represent vimentin. We utilized polyclonal antibodies directed against keratin and immunoperoxidase techniques (PAP) to stain 32 of the more than 300 cases accumulated at the AFIP . All of our material was formalin-fixed, paraffin-embedded. Seventy-five percent of our cases (24/32) showed positive immunoreactivity, a feature that may be of diagnostic help in distinguishing epithelioid sarcoma from modular fasciitis, benign and malignant fibrous histiocytoma, malignant melanoma, and necrotizing granuloma. In these cases, the reaction was enhanced using predigestion with trypsin. The immunoreactivity varied from tumor to tumor, perhaps due to formalin fixation. Since synovial sarcoma and mesothelioma may also be cytokeratin-positive, our findings indicate that keratin immunoreactivity is not confined to epithelial tumors and may also occur in neoplasms traditionally regarded as mesenchymal.
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PMID:Keratin in epithelioid sarcoma. An immunohistochemical study. 620 17


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