Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mouse tumor cell beta-lipotropin (beta LPH) and gamma-lipotropin (gamma LPH) were purified from mouse pituitary tumor cell culture medium by ion exchange chromatography and gel filtration. The mouse tumor cell beta LPH was identified by immunoprecipitation with several antisera to beta-endorphin, generation of opioid bioactivity upon brief treatment with trypsin, and its identity with the molecule previously shown to serve as an intermediate in the biosynthesis of beta-endorphin. Mouse tumor cell beta LPH (Mr = 8200 +/- 250) and gamma LPH (Mr = 4600 +/- 200) are significantly smaller than known mammalian beta LPH (Mr = 10,000) and gamma LPH (Mr = 6300) molecules. The beta-endorphin region of mouse tumor cell beta LPH has the same amino acid composition as ovine, bovine, and camel beta-endorphin, and species-specific differences are thus located in the gamma LPH region of the molecule. Mouse tumor cell beta LPH and gamma LPH lack a methionine residue at what had been considered to be a highly conserved site in their beta-melanotropin-like region. A species-specific radioimmunoassay for mouse tumor cell gamma LPH was developed. Rat pituitary beta LPH and gamma LPH were shown to be similar to the corresponding mouse tumor cell molecules in size and lack of methionine in their beta-melanotropin-like segment.
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PMID:Characterization of mouse tumor cell beta-lipotropin. 48 93

Tumor culture toxohormone (TCT) obtained from cultures of MBQA mouse tumor cells, a line derived from a methylcholanthrene-induced fibrosarcoma (CBA/J origin), suppressed the mitogenic responsiveness of mouse spleen cells (PHA, LPS) as well as the antibody formation to SRBC in vitro. The immunosuppressive activity of toxohormone was readily inactivated by heating at 100 degrees C or treatment with trypsin, but not by DNase and RNase treatment.
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PMID:Immunosuppression induced by "toxohormone" from mouse tumor cells in culture. 49 45

Two pancreatic adenocarcinomas which had been induced in Wistar/Lewis rats by azaserine treatment were transplanted into rats of the same strain by subcutaneous and intraperitoneal injection of minced tumor. Subsequently, we have serially transplanted into non-radiated recipients. Transplanted tumors have maintained evidence of acinar cell differentiation including the presence of zymogen granules in tumors studied by electron microscopy, and of lipase, amylase and trypsin activity in the supernatant of tumor homogenates. Histologically, the tumors vary from poorly differentiated solid carcinomas to well differentiated variants which form acini. Transplanted tumors are locally invasive and have metastasized to lung and liver in some recipients.
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PMID:Transplantation of azaserine-induced carcinomas of pancreas in rats. 50 3

Ehrlich ascites tumor cells spontaneously release cell surface material (glycocalyx) into isotonic saline medium. Exposure of these cells to tritium-labeled 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid (3H2DIDS) at 4 degrees C leads to preferential labeling of the cell surface coat. We have combined studies of the kinetics of 3H2DIDS-label release, the effects of enzymatic treatment, and cell electrophoretic mobility to characterize the 3H2DIDS-labeled components of the cell surface. Approximately 73% of the cell-associated radioactivity is spontaneously released from the cells after 5 h at 23 degrees C. The kinetics of release is consistent with the first-order loss of two fractions; a slow (tau 1/2 = 360 min) component representing 33% of the radioactivity and a fast (tau 1/2 = 20 min) component representing 26%. The remaining 14% of the labile binding may reflect mechanically induced surface release. Trypsin (1 microgram/ml) also removes approximately 73% of the labeled material within 30 min and converts the kinetics of release to that of a single component (tau 1/2 = 5.5 min). The specific activity (SA) of material released by trypsin immediately after labeling is 83% of the SA of the material spontaneously lost in 1 h. However, trypsinization following a 2-h period of spontaneous release yields material of reduced (43%) SA. Neither 3H2DIDS labeling nor the initial spontaneous loss of labeled material alters cell electrophoretic mobility. However, extended spontaneous release is accompanied by a significant decrease in surface charge density. Trypsinization immediately following labeling or after spontaneous release (2 h) reduces mobility by 32%. We have tentatively identified the slowly released compartment as contributing to cell surface negativity.
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PMID:Ehrlich ascites tumor cell surface labeling and kinetics of glycocalyx release. 54 32

To examine the relationship between pre-protein cleavage and nascent chain glycosylation placental mRNA was translated in a reconstituted ascites cell-free system containing microsomal membranes prepared from tunicamycin-treated or untreated ascites tumor cells. In the absence of membranes, first trimester RNA directed the synthesis of the pre-form of the alpha subunit of human chorionic gonadotropin, whereas, in the presence of normal membranes, first trimester RNA directed the synthesis of a glycosylated form of the alpha subunit. Cell-free lysates containing membranes derived from tunicamycin-treated cells synthesized an alpha subunit protein with little, if any, carbohydrate. This protein was apparently sequestered into membranes since it was resistant to the action of trypsin which was added after translation. The pre-peptide of the alpha subunit protein was removed by treated membranes as determined by amino acid sequence analyses. The non-glycosylated protein pre-placental lactogen was also cleaved to its mature form by tunicamycin membranes. These data strongly suggest that, in vitro, glycosylation is not obligatory for pre-protein cleavage and sequestration of these placental protein hormones.
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PMID:Processing of placental peptide hormones synthesized in lysates containing membranes derived from tunicamycin-treated ascites tumor cells. 56 37

Chemotactic factors for malignant neoplastic cells can be generated from either the fifth component of complement or from leukotactic fractions obtained from zymosanactivated serum. Digestion of the fifth component of complement by trypsin initially produced leukotactic activity, but as digestion continues, leukotactic activity is lost and tumor cell chemotactic activity is generated. Separation of the leukotactic activity is lost and tumor cell chemotactic activity is generated. Separation of the leukotactic activity and tumor cell chemotactic activity can be accomplished by gel filtration or isoelectric focusing. Gel filtration indicates that the tumor cell chemotactic factor has a molecular weight of approximately 8000 daltons. Tumor cell chemotactic activity can be generated by trypsinizing the leukotactic fractions isolated by isoelectric focusing. The responses of cultured Walker tumor cells or of Walker ascites tumor cells are dose-dependent and truly chemotactic. Cells from a murine malignant lymphoma do not respond to the complement-derived chemotactic factor for tumor cells, indicating that not all malignant cells share this functional property.
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PMID:Characteristics of the chemotactic response of neoplastic cells to a factor derived from the fifth component of complement. 56 88

Leukocytes contain within their lysosomal granules enzymatic activity that will generate from C5 chemotactic activity for leukocytes (neutrophils) and tumor (Walker carcinosarcoma) cells. Similar activity has been found in phagocytic supernatant fluids from neutrophils and in purified preparations of the leukocyte neutral proteases elastase and cathepsin G. White leukotactic activities can be generated from either the third (C3) or the fifth (C5) components of complement, only C5 serves as a source for generation of the chemotactic activity for tumor cells. As has been previously shown with trypsin, the C5-related chemotactic activities generated by leukocyte proteases are time-dependent: leukotactic activity appears early, then disappears, and is replaced by chemotactic activity for tumor cells. The generation of these chemotactic activities from C5 is blocked by prior treatment of leukocyte preparations with the neutral protease inhibitor Trasylol. The demonstration that enzyme activities from leukocytes have the ability to generate tumor cell chemotactic factors from C5 suggests a possible mechanism by which the development of metastatic lesions may be promoted at sites of tissue injury or inflammation.
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PMID:Digestion of the fifth component of complement by leukocyte enzymes. Sequential generation of chemotactic activities for leukocytes and for tumor cells. 56 81

Egg lectin of Rana japonica, which specifically agglutinates transformed cells but does not agglutinate nontransformed cells and erythrocytes, has been isolated by gel filtration and successive ion-exchange chromatographies on diethylaminoethyl cellulose and carboxymethylcellulose columns and has been characterized as a homogeneous carbohydrate-free protein with a relative molecular weight of 13,500. The lectin, at a concentration of 1 microgram/0.1 ml, causes obvious cytoagglutination of various transformed and tumor cell. The receptor of the Erlich ascites tumor cells which inhibits the lectin-induced agglutination of the Ehrlich ascites tumor cells has been isolated and characterized. The receptor was solubilized from Ehrlich ascites carcinoma cells by treating a tumor cell suspension with insolubilized trypsin, and the solubilized receptor was isolated by gel filtration through Sephadex G-100, followed by ion-exchange chromatography on diethylaminoethyl cellulose. The receptor was identified as a homogeneous glycoprotein having about 25% carbohydrate. The receptor, at a concentration of 4 microgram/0.1 ml, completely inhibited the cytoagglutination of the Ehrlich carcinoma cells caused by three agglutination doses (about 3 microgram/0.1 ml) of the R. japonica lectin.
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PMID:Egg lectin of Rana japonica and its receptor glycoprotein of Ehrlich tumor cells. 57 Apr 54

Glutamate dehydrogenase is very susceptible to carbamylation which results in loss of activity. The effect of a number of proteolytic enzymes (pronase, trypsin and chymotrypsin) on native and carbamylated glutamate dehydrogenase was tested. In all cases, the carbamylated enzyme was at least twice as susceptible to proteolysis as the native enzyme. Antibodies were prepared against glutamate dehydrogenase and carbamylated glutamate dehydrogenase; the carbamylated enzyme was antigenically indistinguishable from the native enzyme. Preliminary experiments indicate that the carbamylated glutamate dehydrogenase is taken up by ascites tumor cells while glutamate dehydrogenase is not. It seems possible that the effects described can be extrapolated to degradation by lysosomes and to other covalently modified enzymes.
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PMID:Increased susceptibility of carbamylated glutamate dehydrogenase to proteolysis. 61 12

Ehrlich ascites tumour cells contain a neutral protease, capable of solubilising fluorescein-labelled telopeptides from fluorescein-labelled polymeric collagen fibrils. The cells also contain an inhibitor for this enzyme and for trypsin. The enzymically inactive enzyme-inhibitor complex can be dissociated with the mercurial thiol agent, mersalyl, with the consequent regain of enzymic activity. The reactivated neutral protease and also trypsin can be inhibited by addition of thiols such as cysteine, mercaptoethanol and dithiothreitol. Trypsin can be protected from inactivation by the tumor inhibitor by addition of cystine or L-1-tosylamido-2-phenylethyl chloromethyl ketone(TosPheCH2Cl)-inactivated chymotrypsin. The evidence suggests that the inhibitor contains a reactive thiol group which exchanges with one or more significant disulphide bridges in trypsin and the neutral protease, resulting in enzyme-inhibitor complex formation and loss of activity. Similarly, thiols interact with these enzymes resulting in a corresponding loss of enzymic activity. The evidence obtained with Tos-PheCH2Cl-inactivated chymotrypsin, which reactivated previously inhibited trypsin and neutral protease, demonstrates that the active site of the enzyme is not involved in the interaction with the thiol of the inhibitor but that the significant disulphide bond in the enzyme is required for the maintenance of the active site conformation. This disulphide exchange mechanism is therefore a form of reversible allosteric control of proteolytic activity and has been shown to be distinct from the mechanism by which soya bean trypsin inhibitor interacts with trypsin.
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PMID:Evidence for the inhibition of trypsin by thiols. The mechanism of enzyme-inhibitor complex formation. 62 6


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