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)

Serine proteases or esterases released from cell cultures into the growth medium were converted to radioactive derivatives by active site labeling with tritiated DFP, both in the presence and absence of other competing active site reagents. The individual labeled enzymes were then identified by SDS-polyacrylamide gel electrophoresis and scintillation autoradiography. Conditioned medium from embryonal mouse fibroblasts transformed by mouse sarcoma virus contained five serine enzymes that were not present in medium from normal cells; two serine enzymes were released by both cell types, and one serine enzyme was found only in medium from normal cells. Two of the enzymes released by transformed cells were identified as plasminogen activators; these accounted for most of the serine enzyme labeling in transformed culture media and for most of the serine enzyme difference between normal and transformed cultures. The culture fluids from two cell strains of human neoplastic origin were examined by the same method. A rhabdomyosarcoma strain released eight serine enzymes (mol wt ranging from 22,500 to 102,000), four of which were plasminogen activators; seven serine enzymes (mol wt 26,000-102,000), including two plasminogen activators, were detected in medium from human melanoma cultures. In terms of electrophoretic mobility two of the plasminogen activators from rhabdomyosarcoma were identical with those from melanoma cultures, while the remaining two rhabdomyosarcoma activators coincided with activators found in commerical urokinase.
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PMID:Serine enzymes released by cultured neoplastic cells. 63 49

We have identified and cloned cDNA for a novel cell-surface protein that we have named Tactile for T cell activation, increased late expression. It is expressed on normal T cell lines and clones, and some transformed T cells, but no other cultured cell lines tested. It is expressed at low levels on peripheral T cells and is strongly up-regulated after activation, peaking 6 to 9 days after the activating stimulus. It is also up-regulated on NK cells activated in allogeneic cultures. It is not found on peripheral B cells but is expressed at very low levels on activated B cells. Tactile-specific mAb immunoprecipitates a band of 160 kDa when reduced and bands of 240, 180, and 160 kDa nonreduced. Using an antiserum produced with affinity-purified Tactile protein to screen a lambda gt11 library, we have identified Tactile cDNA. Northern blot analysis shows an expression pattern similar to that of the protein and transfection of COS cells with the full-length 5.2-kb cDNA results in cell-surface expression. Comparison with the sequence databanks show that Tactile is a member of the immunoglobulin gene superfamily, with similarity to Drosophila amalgam, the melanoma Ag MUC-18, members of the carcinoembryonic Ag family, the poliovirus receptor, and the neural cell adhesion molecule. The deduced primary sequence encodes a protein with three Ig domains, a long serine/threonine/proline-rich region typical of an extensively O-glycosylated domain, a transmembrane domain, and a 45 residue cytoplasmic domain. These data suggest that Tactile may be involved in adhesive interactions of activated T and NK cells during the late phase of the immune response.
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PMID:Identification and molecular cloning of tactile. A novel human T cell activation antigen that is a member of the Ig gene superfamily. 131 46

Syntheses of melanostatin and feldamycin have been completed from L-serine and L-threonine, respectively, and the configuration of unknown asymmetric carbons determined. Feldamycin analogs have also been prepared and the L-tryptophyl analog was the most potent in the depigmentation of Streptomyces bikiniensis and B16 melanoma cells.
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PMID:Synthesis, stereochemistry, and biological properties of the depigmenting agents, melanostatin, feldamycin and analogs. 167 26

The alternatively spliced type III connecting segment (IIICS) region of fibronectin contains two distinct sites that support the adhesion of melanoma cells. These sites are contained within the synthetic peptides CS1 and CS5 (residues 1-25 and 90-109 of the IIICS, respectively). Recently, the cellular receptor for the CS1 site has been identified as the integrin heterodimer alpha 4 beta 1. In this report, we have investigated the role of the CS5 sequence in melanoma cell adhesion and the identity of its receptor. Adhesion to CS5, when presented to cells as an immobilized IgG conjugate, was blocked by antifunctional monoclonal antibodies directed against either the alpha 4 or beta 1 integrin subunits, but not by antibodies against other subunits, implying that alpha 4 beta 1 is also the receptor for CS5. In peptide inhibition experiments, CS5 was inhibitory for melanoma cell spreading on both CS5-IgG and CS1-IgG conjugates; conversely, CS1 inhibited spreading on both CS1-IgG and CS5-IgG. In both cases, peptide inhibition could be outcompeted by increasing the concentration of substrate-bound conjugate. These results suggest that CS1 and CS5 are recognized by the same or overlapping sites on alpha 4 beta 1. The minimal active sequence within CS5, the tetrapeptide Arg-Glu-Asp-Val (REDV), is somewhat related to the Arg-Gly-Asp-Ser (RGDS) sequence that represents a major active site in the central cell-binding domain (CCBD) of fibronectin. When RGDS peptide homologues were tested for their ability to inhibit spreading of melanoma cells on CS1- and CS5-IgG conjugates, GRGDS, GRGES, and REDV were found to be inhibitory, while GRDGS had no effect. In contrast, spreading on a fibronectin fragment containing the CCBD was inhibited by GRGDS only. GRGDS was also able to elute alpha 4 beta 1 specifically from a CS1 affinity column, confirming directly that alpha 4 beta 1-IIICS interactions are sensitive to peptides containing this recognition motif. Because the minimal active sequence within CS1 is the tripeptide Leu-Asp-Val (LDV; Komoriya et al., manuscript submitted for publication), these findings together define a new adhesive recognition sequence, X-Asp-Y, used by alpha 4 beta 1 for binding to fibronectin. The central aspartate residue in this tripeptide is almost always essential, but some flexibility in the amino acid residues at X (glycine, leucine, or glutamic acid) and Y (serine or valine) is tolerated. Potential models for the interaction of the IIICS region with alpha 4 beta 1 are discussed.
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PMID:The CS5 peptide is a second site in the IIICS region of fibronectin recognized by the integrin alpha 4 beta 1. Inhibition of alpha 4 beta 1 function by RGD peptide homologues. 175 Sep 29

Albolabrin, a 7.5-kDa cysteine-rich protein isolated from the venom of Trimeresurus albolabris, contains the arginine-glycine-aspartic acid (RGD) cell recognition sequence found in many cell adhesion-promoting extracellular matrix proteins, such as fibronectin and laminin. Albolabrin belongs to a family of RGD-containing peptides, termed disintegrins, recently isolated from the venom of various vipers and discovered to be potent inhibitors of both platelet aggregation and cell-substratum adhesion. Here we report that albolabrin inhibited the attachment of B16-F10 mouse melanoma cells to either fibronectin or laminin absorbed on plastic. When immobilized on plastic, albolabrin promoted B16-F10 melanoma cell attachment; this was inhibited by either RGD-serine (RGDS) or antibodies to integrins, suggesting that albolabrin binds via its RGD amino sequence to integrin receptors expressed on the melanoma cell surface. In an in vivo experimental metastasis system, albolabrin at a concentration of 300-600 nM inhibited C57BL/6 mouse lung colonization by tail vein-injected mouse melanoma cells and was at least 2000 times more active than RGDS in this assay. We propose that albolabrin inhibits tumor cell metastasis by inhibiting integrin-mediated attachment of melanoma cells to RGD-containing components of the extracellular matrix in the mouse lung.
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PMID:Inhibition of murine melanoma cell-matrix adhesion and experimental metastasis by albolabrin, an RGD-containing peptide isolated from the venom of Trimeresurus albolabris. 187 72

The human T cell-associated serine proteinase-1 (HuTSP-1) is expressed by activated T lymphocytes and is exocytosed upon their interaction with target cells. Here, we report that HuTSP-1 is able to convert single-chain human pro-urokinase into the active two-chain enzyme. Time-dependent activation by HuTSP-1 of recombinant human pro-urokinase as well as natural pro-urokinase derived from human melanoma cells was demonstrated in a chromogenic assay specific for active urokinase type plasminogen activator and in immunoblotting experiments revealing the conversion of single-chain into two-chain urokinase. Control experiments excluded plasmin as the activating agent. These data suggest a novel pathway for plasmin generation during T cell-mediated processes such as immune responses and extravasation of immune cells.
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PMID:Activation of pro-urokinase by the human T cell-associated serine proteinase HuTSP-1. 213 93

Cell adhesion to extracellular matrix components such as fibronectin has a complex basis, involving multiple determinants on the molecule that react with discrete cell surface macromolecules. Our previous results have demonstrated that normal and transformed cells adhere and spread on a 33-kD heparin binding fragment that originates from the carboxy-terminal end of particular isoforms (A-chains) of human fibronectin. This fragment promotes melanoma adhesion and spreading in an arginyl-glycyl-aspartyl-serine (RGDS) independent manner, suggesting that cell adhesion to this region of fibronectin is independent of the typical RGD/integrin-mediated binding. Two synthetic peptides from this region of fibronectin were recently identified that bound [3H]heparin in a solid-phase assay and promoted the adhesion and spreading of melanoma cells (McCarthy, J. B., M. K. Chelberg, D. J. Mickelson, and L. T. Furcht. 1988. Biochemistry. 27:1380-1388). The current studies further define the cell adhesion and heparin binding properties of one of these synthetic peptides. This peptide, termed peptide I, has the sequence YEKPGSP-PREVVPRPRPGV and represents residues 1906-1924 of human plasma fibronectin. In addition to promoting RGD-independent melanoma adhesion and spreading in a concentration-dependent manner, this peptide significantly inhibited cell adhesion to the 33-kD fragment or intact fibronectin. Polyclonal antibodies generated against peptide I also significantly inhibited cell adhesion to the peptide, to the 33-kD fragment, but had minimal effect on melanoma adhesion to fibronectin. Anti-peptide I antibodies also partially inhibited [3H]heparin binding to fibronectin, suggesting that peptide I represents a major heparin binding domain on the intact molecule. The cell adhesion activity of another peptide from the 33-kD fragment, termed CS1 (Humphries, M. J., A. Komoriya, S. K. Akiyama, K. Olden, and K. M. Yamada. 1987. J. Biol. Chem., 262:6886-6892) was contrasted with peptide I. Whereas both peptides promoted RGD-independent cell adhesion, peptide CS1 failed to bind heparin, and exogenous peptide CS1 failed to inhibit peptide I-mediated cell adhesion. The results demonstrate a role for distinct heparin-dependent and -independent cell adhesion determinants on the 33-kD fragment, neither of which are related to the RGD-dependent integrin interaction with fibronectin.
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PMID:RGD-independent cell adhesion to the carboxy-terminal heparin-binding fragment of fibronectin involves heparin-dependent and -independent activities. 230 7

The human melanoma cell lines M21 and MSM-M2 are shown to produce two similar competitive inhibitors of trypsin, a serine proteinase. These proteinase inhibitors inhibited the serine proteinases trypsin and kallikrein with similar efficiency but did not inhibit plasmin (a serine proteinase) or papain (a thiol proteinase). Active synthesis of the inhibitors during cell culture was indicated by the requirement for cell viability, the increase in inhibitory activity of the supernatant with time, and the incorporation of 35S-methionine into the inhibitors. The two inhibitors were stable to heat (70 degrees C) and extremes of pH. Their molecular weights were estimated at 670 and 250 kD, respectively. A screening of the supernatants of five other human melanoma cell lines by HPLC showed that they all released a similar trypsin inhibitory factor not detected in human or bovine serum. The isolation of these proteinase inhibitors facilitates a study of their putative role in tumor growth.
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PMID:Serine proteinase inhibitors produced by human melanoma cell lines. 230 65

A high percentage of the total tyrosinase found in Harding-Passey mouse melanoma occurs as a soluble form. This paper shows that melanosomal tyrosinase can be solubilized by several endogenous proteases to yield active tyrosinase. This enzyme, once proteolytically solubilized, can be further degraded, leading to enzyme inactivation. The nature and specificity of the main proteases involved in the solubilization process change depending on the size and necrosis stage of the tumour. Cathepsin B could be the main protease responsible for the solubilization in small tumours (less than 0.5 g). Large tumours are rich in necrotic cells, and cathepsin D and serine-proteases are the main hydrolytic enzymes involved in the proteolytic action on melanosomes. These results support the view that the high activity of tyrosinase found in the soluble fraction of malignant melanoma is mainly an artefact resulting from degradation of melanosomes by a variety of endogenous proteases, rather than the result of the actual occurrence of high levels of an independent cytosolic isozyme.
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PMID:Action of endogenous proteases on the distribution of tyrosinase isozymes in Harding-Passey mouse melanoma. 250 24

1. The major functional role played by phosphorylation of plasma membrane proteins in the biological properties of tumor cells suggests that identification of protein kinases and their substrates will contribute to our understanding of the molecular basis of the malignant process and of the aberrant behavior of tumor cells. 2. The present study has investigated the phosphorylation of surface proteins of human tumor cells. Incubation of plasma membranes isolated from cultured human melanoma cells with [gamma-32P]ATP in the presence of Ca2+ and ethylene-bis-(oxyethylenenitrilo)-tetraacetic acid (EGTA) resulted in specific phosphorylation of serine and threonine residues on a 75kDa protein (pp75). 3. Neither Ca2+ or EGTA alone, nor any other divalent metal ion tested could induce phosphorylation of pp75. 4. The phosphorylation of pp75 was directly dependent upon the presence of non-ionic detergents, and was influenced by length of incubation and concentration ratio of Ca2+ and EGTA. 5. Incubation of isolated plasma membranes with [gamma-32P]ATP in the presence of Ca2+ and EGTA and immunochemical analysis by Western blotting with an anti pp75 xenoantiserum detected the pp75 in human melanoma, neuroblastoma, ovarian carcinoma and lymphoid T cells and fibroblasts but not in B-lymphoid cells, renal carcinoma cells, peripheral blood lymphocytes and splenocytes. 6. These results suggest the presence of a new class of plasma membrane bound protein kinases activated by chelated calcium and differentially expressed in normal and transformed human cells.
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PMID:Specific phosphorylation by calcium-EGTA complex of a 75 kDa human tumor plasma membrane protein (pp75). 250 5


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