Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have purified and determined the complete primary structure of human stromelysin, a secreted metalloprotease with a wide range of substrate specificities. Human stromelysin is synthesized in a preproenzyme form with a calculated size of 53,977 Da and a 17-amino acid long signal peptide. Prostromelysin is secreted in two forms, with apparent molecular masses on NaDodSO4/PAGE of 60 and 57 kDa. The minor 60-kDa polypeptide is a glycosylated form of the major 57-kDa protein containing N-linked complex oligosaccharides. Zymogen activation by trypsin results in the removal of 84 amino acids from the amino terminus of the enzyme generating a 45-kDa active enzyme species. Human stromelysin is capable of degrading proteoglycan, fibronectin, laminin, and type IV collagen but not interstitial type I collagen. The enzyme is not capable of activating purified human fibroblast procollagenase. Analysis of its primary structure shows that stromelysin is in all likelihood the human analog of rat transin, which is an oncogene transformation-induced protease. The pattern of enzyme expression in normal and tumorigenic cells revealed that human skin fibroblasts in vitro secrete stromelysin constitutively (1-2 micrograms per 10(6) cells per 24 hr). Human fetal lung fibroblasts transformed with simian virus 40, human bronchial epithelial cells transformed with the ras oncogene, fibrosarcoma cells (HT-1080), and a melanoma cell strain (A 2058), do not express this protease nor can the enzyme be induced in these cells by treatment with phorbol 12-myristate 13-acetate. Our data indicate that the expression and the possible involvement of secreted metalloproteases in tumorigenesis result from a specific interaction between the transforming factor and the target cell, which may vary in different species.
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PMID:Human skin fibroblast stromelysin: structure, glycosylation, substrate specificity, and differential expression in normal and tumorigenic cells. 347 4

Guanidinobenzoatase is a trypsin-like protease capable of degrading fibronectin. An inactive form of guanidinobenzoatase is present on the surface of benign naevus cells and these cells stain very weakly with 9-aminoacridine, a known competitive inhibitor of guanidinobenzoatase. Malignant melanoma and metastatic malignant melanoma cells exhibit strong surface staining with 9-aminoacridine and also exhibit strong staining of cytoplasmic RNA with acridine orange. These simple fluorescent techniques have been used to distinguish benign naevus cells from malignant melanoma cells in human skin sections. This difference in cell surface staining with 9-aminoacridine has been demonstrated to be caused by the presence or absence of an inhibitor. The inhibitor can be displaced from the cell surface enzyme and then replaced by an affinity purified inhibitor obtained from fresh liver homogenates. It is proposed that the inhibition or control of cell surface guanidinobenzoatase may be one of the regulatory mechanisms by which benign naevus cells are prevented from developing into malignant melanoma cells.
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PMID:The role of inhibitors in the fluorescent staining of benign naevus and malignant melanoma cells with 9-amino acridine and acridine orange. 350 14

A protein kinase activity (S6PK) that phosphorylates ribosomal protein S6 has been detected in cytosolic extracts prepared from an insulin-sensitive mouse fibroblast-melanoma hybrid cell line. The activity of this enzyme is greatly increased in cells that have been stimulated with insulin or serum for 30 min before preparation of the extract. In the parental melanoma cells, which are insensitive to the growth-stimulatory action of insulin, the activity of the enzyme is lower than in the hybrid cells and is not increased in response to insulin. The insulin-sensitive, serum-sensitive S6PK from the hybrid cells is eluted as a single peak from diethylaminoethyl (DEAE)-cellulose between 0.15 and 0.2 M KCl. The apparent mol wt of the enzyme, as determined by gel permeation chromatography, is approximately 105,000. A second S6 kinase activity from the hybrid cells is trypsin dependent and elutes from DEAE-cellulose at a lower salt concentration than S6PK. In contrast to S6PK, the trypsin-dependent S6 kinase activity does not vary in a consistent manner in response to insulin or serum. Fractions obtained from DEAE-cellulose chromatography of extracts of the hybrid cells have also been assayed for ability to phosphorylate the synthetic octapeptide Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala (S6-1), the structure of which is based on a phosphorylated region of the S6 protein. Two trypsin-dependent peaks of protein kinase activity have been found to phosphorylate this peptide, one eluting at 0.05 M KCl and the other at 0.10-0.15 M KCl. The first peak elutes at the same salt concentration as the trypsin-dependent protein kinase(s) that phosphorylate ribosomal protein S6, while the second elutes slightly, but reproducibly ahead of S6PK. Several properties of the second peak of S6-1 phosphorylating activity suggest that it is not S6PK.
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PMID:Insulin-sensitive, serum-sensitive protein kinase activity that phosphorylates ribosomal protein S6 in cultured fibroblast-melanoma hybrid cells. 352 18

The tumor-induced red blood cell (RBC) cytolysis assay has been used to demonstrate that three B16 melanoma sublines, the F1, F10, and BL6, cause the cytolysis of normal red blood cells in vitro. RBC cytolysis was inhibited for all three sublines by metalloprotease inhibitors. Cell membrane preparations have been prepared for all three sublines and tumor cell membrane-induced RBC cytolysis was also shown to be inhibited by metalloprotease inhibitors. The F10 and BL6 sublines were shown to have cell membrane-bound proteases. The BL6 subline has a cell membrane enriched in an enzyme with a trypsin-like arginine specificity. The trypsin-like protease may have a metal dependence. The BL6 subline has a collagenolytic cell membrane enzymes and a chymotrypsin-like cell membrane enzyme. B16 cell membrane enzymes may be responsible for RBC cytolysis in vitro in a process requiring divalent cations.
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PMID:Analysis of the cell membrane proteolytic enzymes of the B16, F1, F10, and BL6 melanoma and their role in target cell destruction. 354 41

Actin is present in cells in monomeric and polymeric (filamentous) forms. Filamentous actin is distributed in Triton-soluble (cytosolic) and Triton-insoluble (cytoskeletal core) fractions. We have used the DNase 1 inhibition assay and immunofluorescence to investigate the distribution of actin in monomeric and polymeric forms in cloned B16 murine melanoma cell lines of low and high metastatic capacity. The protease trypsin caused rounding up and detachment of both cell lines within 5 min. This was associated with almost complete depolymerization of cytosolic actin filaments but the Triton-insoluble cytoskeleton was not quantitatively affected by trypsin treatment. There were quantitative differences between the clones in their response to incubation in the presence or absence of 10% serum. The highly metastatic cell line contained 35% more actin when incubated in the presence of 10% serum, almost completely distributed to the Triton-insoluble cytoskeleton, an effect not seen in the low metastatic cells.
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PMID:Actin in B16 melanoma cells of differing metastatic potential. Effects of trypsin and serum. 354 35

Tumor necrosis factor (TNF) is cytocidal for human and murine cells when protein synthesis is inhibited by cycloheximide, but some protease inhibitors completely protect these cells from TNF cytotoxicity. Inhibitors of chymotrypsin-like proteases are active at lower concentrations than inhibitors of trypsin-like proteases. Both irreversible inhibitors, such as alkylating compounds, and reversible inhibitors, such as substrates of proteases, protect cells from the cytocidal activity of TNF. This protection is most effective when the cells are pretreated with these inhibitors before addition of TNF. When the protease inhibitors are removed, the cells gradually lose resistance to TNF cytotoxicity. The inhibitors do not interfere with the functioning of TNF-receptor complexes, since SK-MEL-109 melanoma cells treated with a protease inhibitor synthesize a TNF-induced protein. These findings suggest that a protease in involved in the cytocidal action of TNF.
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PMID:Protection from tumor necrosis factor cytotoxicity by protease inhibitors. 359 75

Autostimulatory growth factors may contribute to the ability of malignant cells to escape normal growth controls. We have previously shown that Hs0294 human malignant melanoma cells release into culture medium an acid-soluble, heat-stable, trypsin-sensitive, autostimulatory monolayer mitogen which can be purified from acetic acid extracts of conditioned medium by gel filtration, reverse-phase high-performance liquid chromatography, and preparative electrophoresis. The majority of this melanoma growth-stimulatory activity (MGSA) resides in a 16-Kd moiety, though bioactivity is also associated with 24-26 and less than 14-Kd forms of MGSA (Richmond and Thomas: J Cell Physiol 129:375, 1986). In order to further characterize this growth factor, monoclonal antibodies were prepared against a partially purified preparation of the autostimulatory melanoma mitogen. Monoclonal antibody clones were selected based on supernate inhibition of 3H-thymidine incorporation in serum-free Hs0294 melanoma cultures. One of these, termed FB2AH7, slows, but does not completely block, the growth of Hs0294 cells in serum-free medium in a dose-dependent manner. This antibody does not slow the growth of normal rat kidney fibroblasts, which neither produce nor require this mitogen, in either serum-free medium or medium containing 0.8% calf serum. This monoclonal antibody also blocks the mitogenic effects of partially purified preparations of this melanoma growth stimulatory activity (MGSA) on both Hs0294 cells and normal rat kidney fibroblasts. The FB2AH7 antibody has been demonstrated to bind MGSA by Western blot and by immunoprecipitation procedures. Western blot analysis of reverse-phase high-performance liquid chromatography purified growth factor demonstrated that FB2AH7 antibody binds to the 16-Kd and approximately 13-14-Kd forms of MGSA. FB2AH7 antibody can be used in immunoprecipitation experiments to bind the approximately 13-16-Kd forms of MGSA. The specificity of the binding of FB2AH7 antibody for MGSA but not other growth factors has been demonstrated in a modified dot blot assay. These data thus support the hypothesis that MGSA is an autostimulatory melanoma mitogen distinct from other growth factors.
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PMID:Preparation of a monoclonal antibody to a melanoma growth-stimulatory activity released into serum-free culture medium by Hs0294 malignant melanoma cells. 361 Nov 99

A metalloproteinase with activity against type IV collagen, type I collagen and gelatin has been purified from the cytosol of a highly metastatic mouse melanoma by anion-exchange, zinc-chelated and lectin-affinity column chromatography. The purified enzyme has a molecular mass of approx. 59 kDa and on isoelectric focusing in two-dimensional gels produced three spots with apparent isoelectric points (pI) between 5.7 and 6.1. Enzymic activity with collagen, but not gelatin, substrates was latent, requiring activation by trypsin or organomercurials. Trypsin activation of this metalloproteinase was accompanied by a change in molecular mass, whereas autoactivation after 1 month's storage, was not. The degradation of types I and IV collagen by the melanoma enzyme yielded products of lower molecular masses than those yielded by mammalian collagenases, this characteristic thus differentiating this metalloproteinase from classical collagenases.
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PMID:Purification and characterization of a connective-tissue-degrading metalloproteinase from the cytosol of metastatic melanoma cells. 366 69

Antisera reactive with the ganglioside GM2 were raised by immunizing C57BL/6 mice with the C57BL/6 melanoma JB-RH. Fusion with NS-1 was performed using splenic mononuclear cells from a mouse with high antibody titer. An immunoglobulin M monoclonal antibody (monoclonal antibody 5-3) was identified which was reactive with an antigen that was resistant to heat, trypsin, and Pronase. A panel of purified glycolipids was used to determine the specificity of monoclonal antibody 5-3. Reactivity was restricted to N-acetyl- and N-glycolyl-GM2. No reactivity was detected with asialo-GM2 or other gangliosides. Monoclonal antibody 5-3 was used to define the expression of GM2 on the cell surface of cultured human normal and malignant cells. Reactivity was seen with cell lines derived from 8 of 8 astrocytomas, 5 of 5 neuroblastomas, 7 of 9 sarcomas, 4 of 18 human melanomas, 2 of 4 murine melanomas, 4 of 37 epithelial cancers and with 0 of 6 skin fibroblast and 0 of 2 brain fibroblast lines. GM2, like GD2 and GD3, appears to be a differentiation antigen largely restricted to cells of neuroectodermal origin.
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PMID:A murine monoclonal antibody detecting N-acetyl- and N-glycolyl-GM2: characterization of cell surface reactivity. 373 Oct 79

A human platelet sonicate was evaluated for its effects on the growth of human metastatic melanoma colony-forming cells in soft agar from cells in culture and from biopsies. The addition of platelet sonicate increased both cloning efficiency and proliferative capacity in that more and larger colonies were formed. In more detailed studies under growth-limiting conditions, melanoma cellular responses to known growth factors were compared to the activity found in the platelet sonicate. None of the growth factors tested either alone or in combination, including platelet-derived growth factor, epidermal growth factor, alpha-type transforming growth factor, and beta-type transforming growth factor, were capable of inducing melanoma colony formation to the 12-fold stimulation observed with the platelet sonicate. Treatment of platelet sonicate with dithiothreitol, trypsin, or acid resulted in loss of activity for human melanoma. Our results suggest that human platelets contain an acid-sensitive protein which can support the expression of the transformed phenotype of human melanoma, and this factor is distinct from acid-stable activities previously characterized from human platelets.
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PMID:Stimulation of human metastatic melanoma colony-forming cells by an acid-sensitive factor in human platelet sonicate. 386 28


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