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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of the shutoff of cellular protein synthesis in vaccinia virus-infected cells has been investigated by using in vitro systems. Purified vaccinia cores cause inhibition of endogenous mRNA translation in nonpreincubated reticulocyte lysates and Ehrlich ascites tumor cell-free systems. Translation of viral mRNA from turnip yellow mosaic virus is also impaired in wheat germ cell-free extracts. The block induced by vaccinia cores in protein synthesis is not due to a decrease in the availability of mRNA but rather to an alteration of the cellular translational machinery. No nucleolytic activity able of digesting mRNA could be detected in purified vaccinia cores with three sensitive tests. There is a lack of inhibition in the poly(Phe)-poly(U) system, which bypasses the normal initiation process. An almost complete disaggregation of polyribosomes in the reticulocyte lysate appears when vaccinia cores are present. These results indicate that mRNA translation in a cell-free system is affected predominantly at the level of polypeptide chain initiation.
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PMID:In vitro inhibition of protein synthesis by purified cores from vaccinia virus. 27 32

This work describes the detection, isolation, and partial characterization of a BALB/c mouse fibroblast cell surface antigen. This antigen migrates as a polypeptide of approximately 100,000 daltons in a discontinuous sodium dodecyl sulfate/polyacrylamide gel electrophoresis system, can be labeled by either lactoperoxidase-catalyzed cell surface 125I iodination or metabolic incorporation of [3H]glucosamine, and can be isolated by concanavalin A affinity chromatography. This cell surface glycoprotein is antigenic in BALB/c mice and has been correlated with the rejection of immunogenic tumor cells. Also, antiserum specific for Moloney leukemia virus precipitates the 100,000-dalton cell surface protein from viral and immunogenic spontaneous transformants. This virus-related antigen comigrates on sodium dodecyl sulfate gels with the major iodinated cell surface protein of these transformants. Rabbit antiserum to the purified antigen demonstrates a marked preference for the surfaces of immunogenic tumor cells as compared with normal cells and nonimmunogenic tumor cells.
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PMID:Isolation and characterization of a tumor cell surface antigen from spontaneously transformed BALB/c mouse fibroblasts. 28 13

Serum tissue polypeptide antigen (TPA) and plasma carcinoembryonic antigen (CEA) were simultaneously measured in 108 patients with breast cancer, in 40 healthy women, and in 26 women with benign breast disease. TPA levels were elevated (0.09 microgram/ml or higher) in 53% of 19 patients with primary breast cancer, and CEA levels were elevated (2.5 ng/ml) in 21%. Among 67 patients with metastatic breast cancer, TPA and CEA levels were increased in 70% and 61%, respectively. TPA was positive in 13% and CEA in 8% of the healthy women. CEA levels were not elevated in patients with benign breast disease, but levels of TPA were elevated in 27% of those studied. Elevation of TPA levels was more frequent in patients with visceral metastasis having higher values of the test results. Among 22 women with breast cancer who had no apparent cancer recurrence, TPA levels were elevated in 12 and CEA levels in 6. In another group of 39 patients with metastatic breast cancer who received palliative therapy, a limited correlation was noted between the clinical course of the disease and changes in TPA and CEA values measured in linear fashion. Thus TPA appeared to be equal to CEA as a tumor marker in most areas analyzed.
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PMID:Human tissue polypeptide antigen in breast cancer. 29 6

A series of mouse hybridomas producing monoclonal antibodies against human acute lymphocytic leukemia (ALL) cells was generated and screened for tumor specificity. Among 1200 primary cultures, 60 produced an antibody that could distinguish between the immunizing leukemia cells and an isologous B lymphoblastoid cell line. Of these, two produced an antibody that detects an antigen expressed preferentially on ALL cells and on a subpopulation of normal cells found in the cortex of the thymus. Other normal human lymphoid cells from lymph nodes, spleen, bone marrow, and peripheral blood express only low levels of this antigen. High levels of this "thymus-leukemia" antigen were found on T-ALL cells, T-ALL-derived cell lines, and some "null" ALL cells. By contrast, B-cell leukemias, B lymphoblastoid cell lines, and normal and malignant myeloid cells contain either low or undetectable amounts of this antigen. The thymus-leukemia antigen has been isolated from the membranes of leukemia cells by detergent solubilization and subsequent immunoprecipitation with the monoclonal antibody. Preliminary biochemical characterization shows the antigen to be associated with a polypeptide of Mr approximately 28,000.
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PMID:A human thymus-leukemia antigen defined by hybridoma monoclonal antibodies. 31 41

We studied the pancreatic and enteric hormone profile of a 46-year-old woman who had hyperglycemia and a pancreatic tumor. Before operation, there was no evidence of overproduction of glucagon or insulin. The tumor's ultrastructure had a distinctive endocrine morphology, resembling D cells. Prompted by the recent demonstration of somatostatin in D cells of pancreatic islets, we analyzed the tumor and found a large quantity of immunoreactive somatostatin (301 ng per milligram of tissue). Insulin, glucagon, gastrin, vasoactive intestinal polypeptide and human pancreatic polypeptide were present in only trace quantities. The tumor cells were cultured in monolayers, which remained viable up to 51 days and released somatostatin into the culture medium. In seven insulinomas and two glucagonomas, we found the somatostatin content either much lower (less than 0.6 ng per milligram of tissue) or undetectable. After complete resection of the tumor, our patient became euglycemic and has remained so for the past 20 months.
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PMID:"Somatostatinoma": a somatostatin-containing tumor of the endocrine pancreas. 32 60

We investigated the ribonucleolytic breakdown of poly(U), poly(A), RNA trascribed from calf thymus DNA with E. coli RNA polymerase, ribosomal RNA, tRNA and mengovirus RNA by an enzyme fraction obrained from a postribosomal supernatant of Ehrlich ascites tumor cells. The single-stranded homopolyribonucleotides are preferentially degraded by the enzyme fraction with the production of ribonucleoside 5'-monophosphates. The RNase activity is completely dependent on the presence of Mg2+ ions and is highest at Mg2+ and K+ concentrations optimal for cell-free protein synthesis. Ribonucleoside 5'-monophosphates, ribonucleoside 2'(3')-monophosphates, ribonucleoside 2'(3'),5'-bisphosphates and transition state analogs consisting of vanadyl sulfate and either ribonucleosides or ribonucleoside 5'-monophosphates in a molar ratio 1:1 inhibit the ribonucleolytic activity of the enzyme fraction. The ribonucleoside 2'(3'),5'-bisphosphates and the transition state analogs are the most effective inhibitors. However, only in the presence of ribonucleoside 2'(3'),5'-bisphosphates a concomitant stimulation by 50 to 60% of poly(U)-directed polyphenylalanine synthesis is observed; all the other RNase inhibitors tested also inhibit polypeptide synthesis. The results of preliminary experiments show that poly(U) and ribonucleoside 2'(3'),5'-bisphosphates are well suited as ligands for affinity chromatography of ribonucleases from Ehrlich ascites tumor cells.
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PMID:Inhibition of ribonucleases by ribonucleotides and transition state analogs in cell-free extracts from Ehrlich ascites tumor cells. 32 84

A protocol has been devised to radiolabel proteins secreted by murine fibroblasts in vitro. A radiolabeled polypeptide of molecular weight 35,000 is released into medium in relatively large amounts by transformed cells and in much smaller amounts by nontransformed fibroblasts. This major excreted polypeptide (MEP) is found in the medium of spontaneously transformed mouse cells and in the medium of mouse cells transformed by a DNA tumor virus, RNA tumor viruses, or methylcholanthrene. The appearance of MEP appears to be well correlated with anchorage independence in these transformed cells. MEP can be localized within the cytoplasm of transformed but not untransformed cells by indirect immunofluorescence. The presence of MEP within murine fibroblasts or in their culture medium serves as a novel biochemical marker of transformation. A biological role for this protein has not been assigned.
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PMID:Transformation-dependent secretion of a low molecular weight protein by murine fibroblasts. 35 14

Plasminogen, the inactive precursor of plasmin, a general trypsin-like proteinase, is present at high concentration in blood and in body fluids. Most cells can recruit this proteolytic potential by secreting plasminogen activator (PA) to generate localized proteolysis in the surrounding microenvironment. PA and plasmin are serine enzymes whose pH optima match extracellular pH; further, in view of the large amount of circulating proenzyme and the broad substrate range of plasmin, the possibility that this proteolytic system can initiate a variety of proteolytic reactions or sequences should be kept in mind. PA production is precisely regulated by hormones, temporal programming, or both; and enzyme synthesis is correlated with some physiological and pathological processes requiring proteolysis. Thus PA production is coordinately regulated with ovulation, trophoblast implantation, spermatogenesis, polypeptide hormone synthesis, and some developmental phenomena; and with inflammation, tumour promotion, and neoplasia. Tissue remodelling and cell migration are common to many of these processes. Macrophage (monocyte) and polymorphonuclear leucocyte PA production is modulated by many biologically active substances. Enzyme synthesis is induced and stimulated by stimuli that recruit these cells to sites of inflammation, and it is repressed by anti-inflammatory agents, notably by glucocorticoids.
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PMID:Neutral proteinases of leucocytes and the inflammatory process. 39 97

Line-10 guinea pig hepatoma cells are normally resistant to killing by antibody plus GPC but they are susceptible to killing by antibody plus HuC. Pretreatment of the cells with selected proteolytic enzymes renders the cells susceptible to killing by antibody plus GPC, whereas pretreatment with polypeptide, catecholamine, or steroid hormones renders the cells more resistant to killing by antibody plus HuC. Hormone pretreated tumor cells incubated with proteolytic enzymes remained resistant to antibody-GPC-mediated killing. Enzyme-pretreated cells incubated with hormones were either sensitive or resistant to antibody-GPC-mediated killing depending on the enzyme used to pretreat the cells, the enzyme concentration, the hormone class, and the specificity of the antibody used to sensitize the cells. The enzyme pretreated cells were able to bind amounts of hormone sufficient to render the cells resistant to humoral immune killing. These results suggest that the hormones exert their effects on certain areas of the tumor cell membrane rather than having a generalized effect on the cells. It is postulated that proteins, along with complex lipids, participate in the mechanism whereby tumor cells resist humoral immune killing.
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PMID:Effect of hormones on the killing by antibody and complement of tumor cells treated with proteolytic enzymes. 40 Apr 72

The biosynthesis and secretion of a glycosylated, K-type immunoglobulin light chain (K-46) was studied in a mouse myeloma tumor, mineral oil plasmacytoma-46B. Viable single cell suspensions were prepared from excised tumors and optimal conditions were established for incorporation of amino acid and carbohydrate precursors into the protein synthesized and secreted by the cells. The glucose analog, 2-deoxy-D-glucose, was utilized as an inhibitor of glycosylation to determine the role of glycosylation in the biosynthesis, intracellular transport, and export of the protein from the cell. It was determined that 6 mM 2-deoxyglucose prevents the incorporation of glucosamine, mannose, and galactose into secreted protein, but permits the incorporation of leucine at approximately 40% of control values. The nonglycosylated protein, secreted in the presence of 2-deoxyglucose, was characterized as a nonglycosylated form of K-46 light chain by the following criteria: (a) electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate, (b) reactivity of the nonglycosylated protein with antisera prepared against native, fully glycosylated, K-46 light chain, (c) analysis of the protein by gel filtration techniques, (d) behavior of the protein on lectin-derivatized Sepharose, and (e) analysis of tryptic peptides derived from the protein. We have concluded that 2-deoxyglucose-inhibited cells synthesize and secrete the normal polypeptide chain of K-46 devoid of its carbohydrate side chain indicating that glycosylation is not an essential step in the biosynthesis, intracellular transport, or export of this protein that is normally synthesized and secreted in a glycosylated form. Under conditions of 2-deoxyglucose inhibition, the nonglycosylated form of K-46 light chain constitutes a significantly greater proportion of accumulated intracellular protein, suggesting that the biosynthesis of the polypeptide chain of K-46 light chain proceeds at a nearly normal rate, but that the absence of the carbohydrate side chain of the protein retards, but does not prevent, the intracellular transport of the protein and its export from the tumor cell.
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PMID:Glycoprotein biosynthesis in myeloma cells. Characterization on nonglycosylated immunoglobulin light chain secreted in presence of 2-deoxy-D-glucose. 40 89


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