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)

In vivo and in vitro studies performed on the polar solvent N-methylformamide (NMF), as well as on its association with chemotherapeutic agents or X rays, have clearly demonstrated that this compound is capable of inducing changes in biological characteristics of tumor cells, e.g., cell differentiation. However, the mechanism of action of NMF is far from being elucidated. Hence, in order to better clarify such a mechanism an in vitro study was carried out by using mouse fibroblasts in primary culture (MEF) and human melanoma cultured cells (M14). Results obtained by immunocytochemical and ultrastructural methods with doses of NMF ranging from 0.1 to 7% are reported here. As a general rule, a different sensitivity (in terms of cytopathologic changes induced by NMF) was found between the cell types considered. In fact, melanoma cells appeared to be highly susceptible to the action of the drug, undergoing severe morphological modifications represented mainly by a reversible dose and time-dependent cell rounding and surface blebbing. In contrast, NMF-induced injury in MEF cells was characterized mainly by a simple retraction of the cell body. A cytochemical analysis of the expression of certain membrane antigens (e.g., glycoproteins, epidermal growth factor receptor, B2 microglobulin) in NMF-treated M14 cells undergoing blebbing was also carried out. A randomly distributed labeling of such molecules was observed. Accordingly, freeze-fracturing electron microscopic analysis also displayed a random distribution of intramembrane particles over the plasma membrane. When subcellular changes induced by the drug were investigated, a remarkable modification of cytoskeletal components was detected in both cell types. In particular, cross-linked actin microfilament bundles were easily observed in NMF-exposed MEF cells. Finally, when different experimental conditions which perturb calcium ion homeostasis or restore protein thiol group reduced state were analyzed, a noticeable impairment of the blebbing phenomenon was observed. Thus, a target effect of NMF on the microfilament system, probably leading, in turn, to several subcellular changes and cell surface blebbing, can be hypothesized. Such a cytoskeletal element-dependent cytopathology appears to be related to changes of the oxidized state of such molecules as well as to calcium ion perturbations.
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PMID:Cytoskeleton-dependent surface blebbing induced by the polar solvent N-methylformamide. 142 60

Recent evidence has implicated protein kinase C (PKC) in the etiology of hyperproliferative diseases such as psoriasis and non-melanoma skin cancer. In this study, PKC activity, immunoreactive protein, and phorbol ester-binding kinetics were examined in primary cultures of normal human epidermal keratinocytes (NHEK) in order to elucidate the relationship between PKC and NHEK proliferation and differentiation. NHEK were maintained in a proliferative phase in serum-free low-calcium (0.15 mM) medium, and then were exposed to high calcium (1.6 mM) in order to stimulate growth arrest and differentiation. Staurosporine was inhibitory to Ca(++)-induced differentiation. Scatchard analysis of phorbol binding indicated that exposure to high calcium for 24 h increased the number of binding sites (Bmax) by fivefold. In correlation with the ligand-binding results, PKC activity was extremely low in proliferating (low-calcium) NHEK compared to differentiating cells (high calcium). When assayed after 24, 48, and 72 h, high calcium induced tenfold or greater increases in Ca++/phospholipid-dependent phosphotransferase activity. Immunoblot analysis of NHEK PKC using antibodies directed against the hinge region of PKC alpha/beta also indicated that exposure to high calcium resulted in higher levels of immunoreactive protein. Therefore, PKC in NHEK appears to be upregulated under conditions of Ca(++)-induced growth arrest and differentiation. In addition, NHEK and other human skin cell particulate fractions contain a protein of approximately 116 kDa that is highly immunoreactive to an antibody to PKC alpha/beta, which coelutes from DEAE-sephacel under the same buffer conditions as the 80-kDa PKC.
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PMID:Protein kinase C in normal human epidermal keratinocytes during proliferation and calcium-induced differentiation. 143 Dec 18

Annexins belong to a family of proteins characterized by calcium-dependent binding to the cytoskeleton and phospholipid surfaces. Basing on these properties annexins are discussed to be involved in the regulation of cytodynamic, anticoagulatory and antiinflammatory processes. Since autoantibodies against annexin I had been detected in patients suffering from inflammatory or autoimmune diseases, an impact on the pathophysiological outcome was assumed. Therefore we developed solid phase, enzyme-linked immunoassays for the quantitative determination of autoantibodies directed against six members of the annexin family. Some preliminary results obtained from sera of patients with malignant melanoma show a quite frequent presence of such autoantibodies. These data suggest that autoantibodies are generated against all annexins. Furthermore, in the individual patient autoantibodies of the IgG-type are monospecific, while about 1/4 of the IgM-type are directed against several annexins. These observations imply that for investigation of anti-annexin autoantibodies in inflammatory and autoimmune diseases as well as cancer all members of the annexin family have to be taken into consideration.
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PMID:Detection of human anti-annexin autoantibodies by enzyme immunoassays. 150 59

We present a method for the detection of lymphocytes with specific reactivity to antigens on stimulator cells using flow cytometry. Cultured human T lymphocytes were loaded with the intracellular fluorochrome indo-1 and were mixed with stimulator cells. Using flow cytometry we could detect a specific increase in intracellular calcium in the T lymphocytes as well as conjugation between the T cells and the stimulator cells. Examination of antigen-specific CD4+ and CD8+ T cell clones demonstrated that the vast majority of T cells which were conjugated to antigen-bearing stimulator cells manifested a rapid increase in intracellular calcium. In contrast T cells conjugated to stimulator cells which did not bear specific antigen demonstrated no such increase in calcium. A similar finding was observed when examining polyclonal tumor infiltrating lymphocytes obtained from patients with melanoma. Tumor infiltrating lymphocytes with specific antitumor reactivity demonstrated an increase in intracellular calcium when conjugated to autologous tumor but not to allogeneic melanoma. In contrast to the T cell clones, only a small subpopulation of tumor infiltrating lymphocytes manifested this specific signal upon conjugation with autologous tumor. This suggests that tumor infiltrating lymphocyte cultures contain T cells with varying reactivities to tumor or may also imply heterogeneity in the stimulating tumor cell lines. The method allows for the detection of specific T cells on an individual cell basis in real time. The procedure is not lethal to the cell and sorting and subculturing of reactive T cell populations can be readily performed. The method could also be used to sort stimulator cells based on their ability to elicit an increase in intracellular calcium in selected T cells.
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PMID:Detection of antigen specific T lymphocytes by determination of intracellular calcium concentration using flow cytometry. 156 23

Aberrant signal transduction has been implicated in malignant transformation, growth, and progression. This has led to the proposal to use inhibitors of signal transduction pathways to treat cancer. One approach to circumventing potential toxicity and improving efficacy would be to target pathways upon which cancer cells selectively depend. Pathways associated with the malignant process involve calcium fluxes, the release of arachidonic acid, and the generation of phosphoinositides. In this report, CAI (L651582, NSC 609974), a substituted carboxyamido-imidazole and novel inhibitor of these selected signal transduction pathways, inhibits anchorage-dependent and -independent growth in a large series of human cancer cell lines. CAI pretreatment of HT-29 human colon cancer and 5R ras-transfected rat embryo fibroblast cells inhibits the formation and growth of experimental pulmonary metastases in nude mice. Oral administration of CAI in PEG-400 vehicle arrests growth and metastasis of transplanted human melanoma and ovarian cancer xenografts. No significant gross or histological toxicity was observed at CAI doses yielding blood levels in the concentration range demonstrated to inhibit select signal transduction pathways in vitro. These data indicate the feasibility and demonstrate a potential selectivity and sensitivity of using specific signal transduction inhibitors for the experimental treatment of cancer.
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PMID:In vivo efficacy of a novel inhibitor of selected signal transduction pathways including calcium, arachidonate, and inositol phosphates. 159 30

Dopachrome tautomerase (DT) (EC 5.3.2.3) is a melanocyte-specific, membrane-associated, heat-labile, non-dialyzable, protease-sensitive factor which catalyzes the isomeric rearrangement of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA), apparently through a tautomerization reaction. Metal ions such as Cu, Ni, Co, Zn, Mn, Ca, Al, and Fe can also catalyze the dopachrome/DHICA isomerization. How is the reaction regulated in vivo? An attractive possibility would be that DT is a metalloenzyme. Here we present evidence that this may indeed be the case. Purified preparations of DT and tyrosinase, obtained from Cloudman S91 mouse melanoma cells, were assayed in the presence of a variety of metal chelators including EDTA (predominantly Ca and Mg), EGTA (predominantly Ca), phenylthiourea (PTU) (predominantly Cu), 2,2'-dipyridyl (predominantly Fe); 1,10-phenanthroline (predominantly Fe), and 2,3-dihydroxybenzoic acid (predominantly Fe). In addition, DT activity was assayed in the presence of two non-chelating structural analogs of 1,10-phenanthroline. Results were as follows: (i) iron chelators inhibited DT activity with no effects on tyrosinase activity; (ii) inhibition by the chelators was reversible with the addition of ferrous iron; (iii) 1,10-phenanthroline pre-complexed to ferrous iron was not inhibitory to DT; (iv) non-chelating analogs of phenanthroline were not inhibitory to DT; (v) PTU was inhibitory to tyrosinase but not DT; (vi) Ca2+ and Mg2+ chelators had little effect on either enzyme activity. Finally, studies with glycosylation inhibitors, glycosylase enzymes, and immobilized lectins, indicated that DT is a glycoprotein. The results suggest that DT is a metal-containing glycosylated enzyme, possibly with ferrous iron at its catalytic center.
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PMID:Evidence that dopachrome tautomerase is a ferrous iron-binding glycoprotein. 163 43

Thrombospondin (TS) mediates attachment, spreading, and motility of several cell types through at least four cell binding domains: the amino-terminal heparin binding domain, the type I repeats containing the CSVTCG sequence, the RGDA sequence in the last of the type III calcium binding repeats and the carboxyl-terminal cell or platelet binding domain (CBD). The attachment of human melanoma cells (G361) to the COOH-terminal domain is independent of the RGDA sequence and is inhibited by the monoclonal antibody C6.7. To define the cell binding site(s) within this 212-residue COOH-terminal domain, we have synthesized eight overlapping peptides (seven 30-mers and a final 37-mer) representing the entire sequence of the CBD. Several of these peptides are insoluble in aqueous buffers at high concentration. Cell adhesion assays have been devised which employ covalent coupling of peptides in chaotropic solvents to chemically derivatized plastic 96-well plates. Three synthetic peptides, two of which are nonadjacent in the linear sequence, are potent attachment factors for G361 cells. C6.7 blocks adhesion to one of these peptides, whereas sulfated glycoconjugates inhibit adhesion of cells to all three. Polyclonal antibodies raised against the peptides inhibit cell adhesion to the peptides, the recombinant CBD, and to intact TS. The peptides GRGDSP and VTCG are not inhibitory. These sites are thus independent from the type I repeats and the RGDA sequence of TS. Each of the active peptides inhibits cell attachment to the other active peptides as well as to the CBD and to intact TS. This mutual inhibition suggests that the peptides share a common cellular receptor which may contain an associated glycoconjugate chain. These data indicate that the COOH-terminal cell binding domain of TS contains at least two peptide sequences which contribute to the attachment of a wide variety of cells.
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PMID:Identification of active peptide sequences in the carboxyl-terminal cell binding domain of human thrombospondin-1. 164 9

Previous work from our laboratory has shown that both cyclic AMP and calcium/calmodulin appear to be involved in the regulation of melanogenesis in murine B16 melanoma cells. In these cells as in murine Cloudman S91 cells, melanogenic responsiveness to melanocyte-stimulating hormone (MSH) varies with cell density in culture. Our objective in this study was to learn more about the intracellular systems involved in the control of melanogenesis, particularly the role played by calcium. The melanogenic response to alpha MSH was compared to the response to drugs affecting intracellular free calcium and calmodulin over a range of cell densities in B16F1 cells. alpha MSH-stimulated melanin production was extremely density-dependent but alpha MSH-stimulated cyclic AMP production was independent of cell density. The melanogenic response to agents that increased intracellular calcium (A23187) or inhibited intracellular calmodulin varied with cell density. A drug (TMB8) that lowered intracellular free calcium, however, increased melanogenesis independently of cell density. At high cell density it was found that an elevation in calcium decreased melanogenesis, whereas agents that reduced calcium or inhibited calmodulin activity increased melanogenesis. At low cell density, however, the inhibitory response to A23187 was lost and in some experiments even stimulated melanogenesis. These data suggest that the calcium/calmodulin signalling system has an inhibitory influence on melanogenesis, and its expression, which depends upon cell density, may also modulate the response to stimulatory agents such as alpha MSH.
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PMID:Evidence for a calcium/calmodulin involvement in density-dependent melanogenesis in murine B16 melanoma cells. 166 9

Verapamil, a calcium channel antagonist, inhibits murine B16 melanoma and colon adenocarcinoma C26 tumor metastasis by altering platelet aggregation [Tsuruo, T., et al. (1985) Cancer Chemother. Pharmacol., 14:30-33]. However, the role of calcium homeostasis in regulating several biochemical pathways implicated in other steps of the metastatic cascade suggests that calcium channel antagonists could also inhibit metastasis by other mechanisms. In this report, non-toxic doses of verapamil reversibly decreased human A375M and C8161 melanoma cell invasion and metastasis in a dose-dependent manner. Verapamil reduced cellular invasion and metastases by up to 96% (range 78-96%). Concomitantly, verapamil disrupts microtubule and microfilament organization and inhibits unidirectional cell migration but does not affect cellular adhesion to endothelial monolayers or reconstituted basement membranes. In addition, tumor cells treated with verapamil have a decrease in mRNA of type IV collagenase, a proteinase important in tumor cell degradation of basement membranes. Collectively, these data offer additional evidence regarding the mechanisms of action of verapamil as an anti-metastatic agent.
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PMID:Inhibition of tumor cell invasion by verapamil. 166 59

We examined the ability of bryostatin 1 (Bryo), a novel protein kinase C activator, plus ionomycin (Io), a calcium ionophore, to activate T-cells with specific antitumor activity. Lymphocytes from the draining lymph nodes (DLN) of MCA-105 tumor-bearing host mice were stimulated with Bryo/Io, either fresh or after in vitro stimulation with autologous tumor, and then were incubated in interleukin-2 at 20 units/ml. Lymphocytes sensitized with tumor cells in vitro and then stimulated with Bryo/Io exhibited significant expansion (12-fold) after a total of 3 weeks in culture and moderate cytolytic activity (40% at an effector:tumor cell ratio of (80:1) and were exclusively CD8+ T-cells. DLN cells activated immediately with Bryo/Io, without tumor antigen sensitization in vitro, displayed marked growth (130-fold expansion) over 3 weeks in culture, had weak cytolytic activity (8% at an effector:tumor ratio of 80:1), and were a mixed population of CD8+ and CD4+ cells. Despite the differences in phenotypes and in cytotoxicity, both groups of DLN cells were highly effective in vivo against MCA-105 pulmonary metastases. Bryo/Io-activated DLN cells from MCA-105 tumor-bearing hosts had no therapeutic efficacy against B16 melanoma or MCA-203 sarcoma metastases. Lymph node cells from normal mice and non-draining lymph node cells from tumor-bearing hosts could be expanded with Bryo/Io to a degree similar to that of DLN cells but had no antitumor activity. Phenotypic analyses and in vitro and in vivo depletion studies demonstrate that CD8+ cells mediated tumor regression.
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PMID:Activation and growth of murine tumor-specific T-cells which have in vivo activity with bryostatin 1. 173 41


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