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

The human Me14-D12 antigen is a cell surface glycoprotein regulated by interferon-gamma (IFN-gamma) on tumor cell lines of neuroectodermal origin. It consists of two non-convalently linked subunits with apparent mol. wt sizes of 33,000 and 38,000. Here we describe the molecular cloning of a genomic probe for the Me14-D12 gene using the gene transfer approach. Mouse Ltk- cells were stably cotransfected with human genomic DNA and the Herpes Simplex virus thymidine kinase (TK) gene. Primary and secondary transfectants expressing the Me14-D12 antigen were isolated after selection in HAT medium by repeated sorting on a fluorescence activated cell sorter (FACS). A recombinant phage harboring a 14.3 kb insert of human DNA was isolated from a genomic library made from a positive secondary transfectant cell line. A specific probe derived from the phage DNA insert allowed the identification of two mRNAs of 3.5 kb and 2.2 kb in primary and secondary L cell transfectants, as well as in human melanoma cell lines expressing the Me14-D12 antigen. The regulation of Me14-D12 antigen by INF-gamma was retained in the L cell transfectants and could be detected both at the level of protein and mRNA expression.
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PMID:A novel interferon-gamma regulated human melanoma-associated antigen, gp33-38, defined by monoclonal antibody Me14-D12. II. Molecular cloning of a genomic probe. 254 4

We previously demonstrated that membrane vesicles shed by the F10 variant of the murine B16 melanoma cell line inhibited the induction by interferon-gamma (IFN) of murine macrophage immune response region-associated (Ia) antigen expression. In this paper we present evidence that the inhibition of macrophage Ia antigen expression is a selective effect of vesicles and characterize its temporal requirements. Membrane vesicles shed from F10 cells did not affect the expression of macrophage H-2K or H-2D antigens under conditions shown to profoundly inhibit Ia antigen expression. Similarly, the induction of plasminogen activator and interleukin 1 from macrophages was not inhibited by the vesicles. The vesicles did not measurably decrease total cellular RNA or protein synthesis. Macrophages were sensitive to the inhibitory effects of the vesicles during the induction and maintenance phases of Ia expression. Pretreatment of macrophages with vesicles before culture with IFN did not reduce the induction of Ia. The rate of decline of Ia expression after removal of IFN was unaffected by the presence of vesicles. Removal of vesicles from cultures of IFN-treated macrophages resulted in only a partial recovery of Ia expression, suggesting that the inhibition of Ia expression may be a slowly reversible process. The selective and partially reversible inhibition of Ia expression by vesicles shed from the plasma membrane of tumor cells is a possible mechanism whereby tumor-bearing hosts may become immunocompromised.
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PMID:Membrane vesicles shed by murine melanoma cells selectively inhibit the expression of Ia antigen by macrophages. 257 42

Recent evidence has suggested that stress may suppress the immune system and increase the frequency and severity of viral and neoplastic disease. The mechanisms for stress-induced modulation of immune function are unclear, but several neuropeptides are thought to be involved. Because macrophages play an important role in the host defense against infection and neoplasia, several stress-related neuropeptides were screened in efforts to determine whether these substances affect macrophage-mediated tumoricidal activity. Adrenocorticotropin and noradrenaline each completely blocked the capacity of mouse recombinant interferon-gamma (INF-gamma) to activate murine peritoneal macrophages to a tumoricidal state as measured by the lysis of 125I-UdR-labeled melanoma target cells. Vasoactive intestinal peptide significantly potentiated the suppressive effects of noradrenaline. In contrast, neurotensin markedly enhanced the cytolytic capability of peritoneal macrophages activated with INF-gamma. Several other neuropeptides, including substance P, alpha-endorphin, beta-endorphin, Leu-enkephalin, and Met-enkephalin, had no effect on macrophage activation. These findings demonstrate that selected stress-related neuropeptides and neurohormones significantly modulate the capacity of macrophages to attain a tumoricidal state and suggest that alteration of macrophage function by neuropeptides may be a prominent feature of stress-induced enhancement of neoplastic disease.
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PMID:Modulation of macrophage-mediated tumoricidal activity by neuropeptides and neurohormones. 258 37

Treating human melanoma lines with dibutyryl adenosine 3':5'-cyclic monophosphate (dbc AMP) resulted in morphologic changes associated with the altered expression of cell surface antigens. After treatment, cells developed long cellular projections characteristic of mature melanocytes and showed the presence of an increased number of Stage II premelanosomes. In addition, induction of melanin synthesis, detected as brown perinuclear pigmentation, was observed. The AMP further drastically reduced the growth rate of the five melanoma cell lines that were tested. The influence of dbc AMP was completely reversible 3 days after the agent was removed from the culture medium. The antigenic phenotype of the melanoma lines was compared before and after dbc AMP treatment. This was done with four monoclonal antibodies directed against major histocompatibility complex (MHC) Class I and II antigens and 11 monoclonal antibodies defining eight different melanoma-associated antigenic systems. Treatment with dbc AMP reduced the expression of human leukocyte antigen (HLA)-ABC antigens and beta-2-microglobulin in five of five melanoma lines. In the two HLA-DR-positive cell lines dbc AMP reduced the expression of this antigen in one line and enhanced it in the other. No induction of HLA-DR or HLA-DC antigens was observed in the Class II negative cell lines. Furthermore, dbc-AMP modulated the expression of the majority of the melanoma antigenic systems tested. The expression of a 90-kilodalton (KD) antigen, which has been found to be upregulated by interferon-gamma, was markedly decreased in all the five cell lines. A similar decrease in the expression of the high molecular weight proteoglycan-associated antigen (220-240 KD) was observed. The reduced expression of Class I and II MHC antigens as well as the altered expression of the melanoma-associated antigens studied were shown to be reversible after dbc AMP was removed. Our results collectively show that the monoclonal antibody-defined melanoma-associated molecules are linked to differentiation. They could provide useful tools for monitoring the maturation of melanomas in vivo induced by chemical agents or natural components favoring differentiation.
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PMID:Cyclic AMP induces differentiation in vitro of human melanoma cells. 283 5

Staphylococcal enterotoxin A (SEA), a protein isolated from culture supernatants of Staphylococcus aureus, is a potent T-cell mitogen and an inducer of interferon-gamma (IFN-gamma). We report here that SEA exhibits a number of significant in vitro immunomodulatory functions. In vitro treatment of human peripheral blood monocyte-depleted lymphocytes with SEA resulted in significant augmentation of their natural killer cytotoxicity against target cells from hemopoietic (K562, Daudi) or solid (melanoma, lung, colon) human tumor cell lines. SEA was found to be more effective than interferons-alpha (natural or Escherichia coli-derived) in augmenting natural killer (NK) cytotoxicity of peripheral blood lymphocytes. Studies on the kinetics of the augmentation revealed a significant increase of NK within 3 hr of in vitro treatment with SEA at 37 degrees C. A neutralizing monoclonal antibody specific for human IFN-gamma did not affect the augmentation of natural killer cytotoxicity by SEA, suggesting that SEA augmented natural killer cytotoxicity primarily by a mechanism not involving induction of interferon-gamma. Furthermore, in vitro treatment with SEA resulted in significant augmentation of antibody-dependent cell-mediated cytotoxicity and of natural killer-like cytotoxicity, generated in mixed lymphocyte culture, against the K562 targets. Induction of suppressor cells to proliferative responses of autologous or allogeneic mononuclear cells to phytohemagglutinin (PHA) or to allogeneic cells in mixed lymphocyte culture was observed after in vitro treatment of peripheral blood mononuclear leukocytes with SEA for 24 or 48 hr at 37 degrees C. In addition, the presence of SEA in mixed lymphocyte cultures (MLC) resulted in significant inhibition of the generation of specific T-cell-mediated cytotoxicity in MLC. These results suggest that SEA, which may be involved in S. aureus infections and in treatment with extracorporeal perfusion systems over S. aureus columns, can regulate a number of significant lymphoid functions.
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PMID:Immunomodulation of human leukocytes by staphylococcal enterotoxin A: augmentation of natural killer cells and induction of suppressor cells. 294 28

We have induced fresh peripheral blood K/natural killer cells to lyse a variety of target cells by coating them with anti-Fc gamma receptor (anti-Fc gamma R) (CD16) antibody hetero-cross-linked with anti-target cell antibody. The cytotoxic cell mediating this activity is different, as judged by depletion studies, from the CD3+, CD8+ T cell which is targeted by anti-CD3 cross-linked to anti-target cell antibody. Targeted K cell activity from some donors is enhanced by exposure to interleukin 2 but not interferon-gamma; other donors exhibit high amounts of this activity without stimulation. Specificity of lysis mediated by targeted K cells is dictated by the specificity of the anti-target cell antibody within the heteroconjugate, and bystander cells are not lysed by targeted K cells. Hetero-cross-linked antibodies containing anti-histocompatibility leukocyte antigen class I instead of anti-Fc gamma R (CD16) do not promote lysis, suggesting that the bridging of the target cell to Fc gamma R on the K cell is required to activate the lytic process. Lysis mediated by targeted K cells is much less inhibitable by polymerized IgG than is classical antibody-dependent cellular cytotoxicity. Fresh human melanoma cells are lysed specifically by K cells coated with anti-Fc gamma R (CD16) cross-linked to the 96.5 anti-melanoma antibody. In vivo, targeted K cells prevent tumor growth at low effector to target ratios in Winn-type tumor neutralization assays. Targeted K cells may therefore provide a new immunotherapeutic approach for the destruction of detrimental cells, such as tumor and virally infected cells.
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PMID:Human K/natural killer cells targeted with hetero-cross-linked antibodies specifically lyse tumor cells in vitro and prevent tumor growth in vivo. 295 24

In this report a method for the affinity purification and radiolabeling of recombinant mouse interleukin (IL)-4 is described. It is shown on the basis of several criteria that IL-4 retains full biologic activity after radioiodination and can therefore be used as a valid model for measuring the binding characteristics of native IL-4. By using Scatchard plot analysis of equilibrium binding data, it is demonstrated that 125I-IL-4 binds to a high affinity cell surface receptor which is expressed by both hemopoietic and nonhemopoietic cells. The dissociation constant for 125I-IL-4 (Kd = 20 to 60 pM) corresponds to the concentration of IL-4 which gives 50% biologic activity (i.e., 10 to 30 pM). Binding of 125I-IL-4 is rapid (t1/2 of 2 min), whereas dissociation occurs at a slow rate (t1/2 approximately 4 hr). The IL-4 receptor shows a high degree of specificity. Whereas unlabeled mouse IL-4 competed with mouse 125I-IL-4 in an equimolar fashion for binding to IL-4 receptors, several other lymphokines, including mouse IL-2, IL-3, interferon-gamma, granulocyte-macrophage colony-stimulating factor, and human IL-1, IL-2, and IL-4 were unable to inhibit, even at molar excesses of 400 to 800-fold. At 37 degrees C, 125I-IL-4 is rapidly internalized (approximately 200 molecules/cell/min) by HT-2 cells, with at least 85% of cell surface receptors being functional in this respect. Receptors for IL-4 were found to be expressed by subclasses of T and B cells, mast cells, macrophages, and by cells of the myeloid and erythroid lineages. This wide distribution of receptor expression closely matches the known spectrum of biologic activities of IL-4, including proliferation and/or differentiation of T and B cells, mast cells and granulocytes, and induction of macrophage antigen-presenting capacity. IL-4 receptors were also found on a variety of nonhemopoietic cells such as cloned stromal cell lines from the bone marrow, spleen, thymus, and brain, and on muscle, brain, melanoma, fibroblast, and liver cells. Indeed, only 5 of more than 90 cell types tested have undetectable numbers of IL-4 receptors. The biologic effects of IL-4 on nonhemopoietic cells have not yet been reported and await elucidation.
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PMID:Expression of high affinity receptors for murine interleukin 4 (BSF-1) on hemopoietic and nonhemopoietic cells. 296 13

Human HT-29 colon carcinoma and HeLa D98/AH2 and SK-MEL-109 melanoma cells were sensitive to synergistic growth inhibition by concentrations of recombinant human tumor necrosis factor (rTNF) and interferon-gamma (rIFN-gamma) which individually were only slightly inhibitory. We investigated whether this synergism could be explained by the presence of an increased number of TNF receptors in cells treated with rIFN-gamma. These receptors were measured by incubating cells resuspended from monolayers with 125I-rTNF. HT-29 cells treated for a few hours with rIFN-gamma could bind more 125I-rTNF than control untreated cells, but this binding returned to the level of control cells after 24 hr. The treatment with rIFN-gamma did not change the binding affinity of TNF receptors, but increased their number to 1800 per cell from a basal level of about 800 per cell. Inhibitors of RNA synthesis prevented this increase. HT-29 cells were significantly more growth-inhibited when treated first for 6 to 12 hr with rIFN-gamma and then with rTNF, than when treated first with rTNF and then with rIFN-gamma. Untreated HeLa D98/AH2 and SK-MEL-109 cells had 2400 and 9000 receptors per cell, with a KD similar to that of HT-29 cells (approximately 2 X 10(-10)M). A significant increase in TNF receptors after treatment with rIFN-gamma was observed in HeLa D98/AH2, but not in SK-MEL-109 cells. No increase in TNF receptors was detected in cells treated with rIFN-alpha 2. These results indicate that the synergism between rTNF and rIFN-gamma may be due, at least in part, to a transient induction of the synthesis of TNF receptors by rIFN-gamma in cells with a relatively low number of these receptors.
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PMID:Induction of the synthesis of tumor necrosis factor receptors by interferon-gamma. 300 11

Culture supernatants of several human T cell leukemia virus infected cell lines were assessed for the induction of tumoricidal activity against human melanoma target cells in a 72-hr assay. Two cell lines, MT-2 and C10/MJ2, were found to produce high levels of MAF activity constitutively. However, the MT-2 cell line, unlike C10/MJ2, produced little interferon. MT-2 MAF was distinct from interferon-gamma by a number of biochemical and serological criteria. The MAF activity was associated with a non-glycosylated, acid stable protein which has an apparent molecular weight of 55,000 and an isoelectric point of 5.5. Furthermore, this molecule is not related to any of the known lymphokines or cytokines such as the interleukins or colony stimulating factors.
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PMID:Constitutive production of a non-interferon macrophage activating factor by HTLV-transformed T cells. 302 62

The cytostatic and cytotoxic activity of human recombinant tumor necrosis factor (rTNF) was assayed on different tumor cell lines. Human BT-20 breast and ME-180 cervix cancer cells were growth-inhibited by rTNF, whereas two other cell lines were not significantly inhibited. However, when protein synthesis was inhibited by cycloheximide, rTNF was cytotoxic for these cells but not for BT-20 cells. This finding suggested that different mechanisms are responsible for the cytostatic and cytotoxic activity of rTNF. The sensitivity of different cell lines to rTNF could not be correlated with a high number or affinity of rTNF receptors. Occupancy of only a few receptors was sufficient for rTNA cytotoxicity, but an increase in receptor number after treatment with interferon-gamma, or a decrease after pretreatment with cycloheximide, correspondingly enhanced or depressed the cytotoxicity of rTNF. It seemed possible that some cells could be protected from this effect of rTNF by synthesizing "protective" proteins. While searching for such proteins, we observed that rTNF induced the synthesis of two polypeptides in SK-MEL-109 melanoma cells, but not in other cancer cells. Actinomycin D added with rTNF abolished synthesis of these polypeptides, suggesting that rTNF induced transcription of the corresponding mRNAs. Surprisingly, rTNF stimulated growth of SK-MEL-109 cells cultured in medium with low serum.
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PMID:Cytostatic and cytotoxic activity of tumor necrosis factor on human cancer cells. 303 Nov 63


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