Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microsomal membranes from A875 human melanoma cells contain nerve growth factor receptors (NGF-receptors) which appear to belong to a single class with homogeneous binding properties, as determined by Scatchard plots. NGF-receptors in these membrane preparations are also uniformly highly sensitive to tryptic proteolysis, and 125I-NGF bound to NGF-receptor in these membranes is rapidly dissociated in the presence of a high concentration of unlabeled NGF. However, analysis of 125I-NGF dissociation kinetics indicated that two classes of NGF-receptor were present in these membranes. Thus, NGF-receptors can express either high or low affinity trypsin-sensitive states in addition to the high affinity trypsin resistant NGF-receptor state described previously (Buxser, S. E., Kelleher, D. J., Watson, L., Puma, P., and Johnson, G. L. (1983) J. Biol. Chem. 258, 3741-3749). The high affinity trypsin-sensitive and low affinity trypsin-sensitive states correlate with 200- and 90-kDa 125I-NGF X NGF-receptor complexes observed in photoaffinity cross-linking experiments. The absence of differences in peptide maps generated from the two sizes of NGF-receptor proteins together with structural and binding data strongly indicates that the 200-kDa NGF-receptor protein is a complex, probably a dimer, consisting of two 80-kDa NGF-receptor proteins associated with a single beta-NGF dimeric molecule. A model is proposed which relates structural states of NGF-receptors with specific receptor binding properties. The model provides an alternative explanation for binding phenomena previously attributed to negative cooperativity.
 ...
PMID:Properties of the nerve growth factor receptor. Relationship between receptor structure and affinity. 298 77

Plasmodium falciparum-infected erythrocytes (IRBCs) adhere specifically to venular endothelium and thereby evade spleen-dependent immune mechanisms. We have investigated the molecular basis of cytoadherence. We report here that the capacity for cytoadherence of IRBCs is correlated with the expression of a family of variable proteins on the surface of IRBCs. Essential to these studies was the use of in vitro techniques for modulating the cytoadherence phenotype of cloned parasites. In initial studies, we found culture-adapted parasites to be poorly cytoadherent or noncytoadherent. To select for cytoadherent parasites, we incubated knobbed IRBCs with C32 melanoma cells and cultured the adherent cells. Repeated rounds of selection produced parasites with increased cytoadherence. To select for noncytoadherent parasites, we cultured the cells that did not adhere to C32 melanoma cells. Cytoadherent IRBCs from two different cloned isolates had large (Mr greater than 2.4 x 10(5) radioiodinatable proteins that differed in size between the isolates but had in common the biochemical properties of trypsin sensitivity and insolubility with Triton X-100. The proteins were not detected with uninfected erythrocytes, indicating that they were parasite determined, nor were they detected with IRBCs containing parasites cultured for many months without selection. With continued selection for the cytoadherent phenotype, additional IRBC surface proteins with larger molecular sizes (Mr 2.9 x 10(5) and 3.2 x 10(5] appeared. A sequence of reversible changes in the cytoadherence phenotype of cloned parasites was accompanied by variation in the molecular size of the IRBC surface protein. Increased cytoadherence was correlated with expression of larger proteins and decreased cytoadherence was correlated with expression of smaller proteins; there was no change in the molecular size of two other parasite proteins associated with the IRBC membrane. The results indicate that the expression of this family of proteins is closely linked to the cytoadherence phenotype of the parasites, suggesting that the members of the protein family have a role in mediating cytoadherence between IRBCs and endothelial cells.
 ...
PMID:Cytoadherence by Plasmodium falciparum-infected erythrocytes is correlated with the expression of a family of variable proteins on infected erythrocytes. 304 11

An inhibitor of plasminogen activator (PA) secreted by a tumorigenic, but non-metastatic, rat mammary adenocarcinoma cell line has been purified to apparent homogeneity and characterized. It strongly inhibited human urokinase, but was 100 times less potent in inhibiting bovine trypsin and had no effect on plasmin or thrombin. A secreted, urokinase-type PA (Mr 48 000) and a cell-associated PA from a metastatic rat adenocarcinoma cell line were also strongly inhibited. In contrast, a tissue-type PA (Mr 66 000), secreted by human melanoma cells, was only slightly inhibited. Purified inhibitor showed a band of Mr 66 000 in sodium dodecyl sulphate/polyacrylamide gel electrophoresis and an isoelectric point of 4.5 after chromatofocusing. The inhibition of human urokinase was non-competitive.
 ...
PMID:Purification and characterization of an inhibitor of plasminogen activator released by rat mammary adenocarcinoma cells. 308 43

We examined tyrosinase activity in pigmented specimens from three cases of ocular malignant melanoma. Tissue (cholate-trypsin-treated) extract was prepared in cholate-phosphate buffer by homogenization, centrifugation, trypsin digestion, and hydroxylapatite column chromatography. Tyrosinase activity was spectrophotometrically assayed as dopa (L-3,4-dihydroxylphenylalanine) oxidase activity. Tyrosinase activity was detected in the cholate-trypsin-treated extracts. Enzyme activity was inhibited by phenylthiourea but not by 3-iodo-tyrosine. The enzyme was inactivated when extract was preheated or digested with pronase. We believe that our findings confirm the presence of tyrosinase activity in ocular malignant melanoma.
 ...
PMID:Tyrosinase activity in human ocular malignant melanoma. 308 85

Cultured human melanoma and gastrointestinal carcinoma cells were detached from substrate and further dissociated by placing the culture vessel into a water-filled ultrasonic cleaner (43 kHz) and sonicating it for 10-50 s. Plating efficiency and long-term growth of three melanoma cell lines were similar after ultrasound or trypsin detachment. Binding of monoclonal antibodies that define normal and tumor-associated antigens on melanoma and colorectal carcinoma cells was not affected by ultrasound in 21 out of 23 cases. The 40 kDa colorectal carcinoma-associated antigen defined by monoclonal antibody CO 17-1A was more highly expressed after ultrasonication than trypsinization. The antigen defined by antibody CO 44.1 on these cells was more sensitive to sonication. This method represents a rapid, effective and gentle alternative to trypsin detachment of cultured cells, especially when repeated cell washing or centrifugation steps are required.
 ...
PMID:Rapid dissociation of adherent human tumor cells by ultrasound. 331 90

The mechanism of the cytostatic and cytocidal activities of TNF was studied in human tumour cells. BT-20 breast and ME-180 cervical cancer cells were significantly growth-inhibited by TNF, but other cells were not. When protein synthesis was inhibited by cycloheximide, however, TNF was cytotoxic for all cells except BT-20 cells. This suggests that different mechanisms are responsible for the cytostatic and cytocidal activities of TNF. The sensitivity of different cell lines could not be correlated with the number or affinity of TNF receptors. Some protease inhibitors completely protected human and murine cells from TNF cytotoxicity. Inhibitors of chymotrypsin-like proteases were more effective than inhibitors of trypsin-like proteases. Reversible and irreversible inhibitors (such as alkylating compounds) were both protective. The cells were best protected when pretreated with inhibitors before the addition of TNF. When the protease inhibitors were removed the cells gradually lost their resistance to TNF cytotoxicity. The inhibitors did not interfere with the functioning of TNF-receptor complexes, since SK-MEL-109 melanoma cells treated with a protease inhibitor synthesized TNF-induced proteins. These findings suggest that a protease is involved in the cytocidal activity of TNF.
 ...
PMID:Cytocidal activity of tumour necrosis factor: protection by protease inhibitors. 333 13

Melanoma growth stimulatory activity (MGSA) is an endogenous growth factor produced by human malignant melanoma cells. When purified from conditioned medium from the Hs0294 human melanoma cell line, MGSA has been shown to be most reproducibly associated with a 16 kDa acid and heat stable moiety which is sensitive to trypsin and dithiothreitol. Monoclonal antibodies to MGSA have been produced. This report describes the use of FB2AH7 monoclonal antibody to prepare an immunoaffinity resin which binds the MGSA produced by Hs0294 cells. This resin was used to purify the MGSA antigen from Hs0294 human melanoma extracts and medium conditioned by the Hs0294 melanoma cell line. The immunoaffinity eluant obtained from both sources produced a significant stimulation in [3H]thymidine incorporation into DNA in Hs0294 cells and yielded similar profiles when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Upon elution of the material from the polycrylamide gels, a 16 kDa moiety was found to be more reproducibly active in the MGSA [3H]thymidine bioassay and enzyme-linked immunoadsorbent assay. The bioactivity of the 16 kDa material represents a 235,000-fold purification of MGSA.
 ...
PMID:Immunoaffinity purification of melanoma growth stimulatory activity. 334 63

A low metastatic clone, G6, was isolated from the B16 melanoma cell line by cloning procedure. When the cells were cultured in vitro with fibroblasts from newborn mice, the lung-colonizing potential of G6 cells was substantially increased. The effect of coculture depended on the number of the fibroblasts. The elevated colonizing potential of G6 cells was reversed to the original low potential by subculturing them for 20 days without the fibroblasts. The culture medium conditioned by G6-fibroblast coculture demonstrated an activity to enhance the lung-colonizing potential of G6 cells, whereas the medium from the culture of fibroblasts alone showed only a little activity. The growth rate and plating efficiency of G6 cells cultured with the fibroblasts or in the conditioned medium did not differ from those of uncocultured G6 cells. The potentiating activity in the conditioned medium was nondialyzable and stable to heating at 80 degrees C for 10 min, but was lost after heating for 10 min at 120 degrees C, or by the treatment with trypsin. These results indicate that the enhancement of lung-colonizing potential of G6 cells could be mediated by a soluble factor(s) released from cocultured fibroblasts.
 ...
PMID:Enhancement of metastatic capacity of fibroblast-tumor cell interaction in mice. 334 17

The study of the autologous immune response to cancer avoids the difficulties encountered in the use of xenoantisera and may identify antigens of physiological relevance. However, the low titer and incidence of autologous antibody to melanoma have hampered further evaluation. By utilizing acid dissociation and ultrafiltration of serum, we have been able to augment the detectable autologous immune response to melanoma in the majority of patients studied. In autologous system Y-Mel 84:420, serum S150 demonstrated a rise in titer from 1:32 in native sera to 1:262,044 after dissociation. The antigen detected by S150 was found to be broadly represented on melanoma, glioma, renal cell carcinoma, neuroblastoma, and head and neck carcinoma cell lines. It did not react with bladder or colon carcinoma, fetal fibroblasts, pooled platelets, lymphocytes and red blood cells, or autologous cultured lymphocytes. Using polyacrylamide gel electrophoresis, S150 detects a 66,000-mol wt antigen in spent tissue culture media and serum ultrafiltrate. In cell lysate two bands between 20,000 and 30,000 mol wt are detected by S150. The 66,000-mol wt antigen is sensitive to trypsin digestion and but is resistant to pepsin and heat inactivation. Exposure of spent media to trypsin results in the development of a 24,000-mol wt band that appears to correspond to the antigen detected in the cell lysate. The difference between the antigens detected in the cell lysate as compared with spent media and serum ultrafiltrate may be due to degradation during cell lysis. We conclude that melanoma-associated antigens are present in the serum of patients with melanoma and are shed or secreted by their tumor cells.
 ...
PMID:Isolation and partial characterization of melanoma-associated antigens identified by autologous antibody. 338 49

The behaviour in vivo of tight and loose variants of murine melanoma cells is further characterized. In vitro clonal morphology is reproduced on a variety of substrates. Results suggest that repeated selection of loose cells can co-select for cells with high metastatic and colonization potentials. Measurement of cell motility shows that 1G3 (loose) cells are more motile than 1G8 (tight) which are restricted to movements within clonal boundaries. Studies of adhesive properties show that loose cells are more easily detached from the substrate with trypsin or EDTA and that both cell lines attach more quickly to monolayers of loose cells than to tight ones. No gross differences are found either in attachment rates to plastic and ECM or in aggregation and disaggregation rates. Analysis of the cell surface has not revealed any differences between 1G8 and 1G3 in the sialylation of terminal galactose and N-acetylgalactosamine residues or in neuraminidase releasable sialic acid. The binding patterns of iodinated lectins to SDS-PAGE separated proteins are similar for both lines except for one 85/90 KD protein which is more abundant in 1G3 than 1G8 cells after neuraminidase treatment. The results show enhanced differences in metastatic potential of tight and loose clones after selective cloning and that there may be important differences in motility and cell-substrate interactions.
 ...
PMID:Morphological and metastatic murine melanoma variants: motility, adhesiveness, cell surface and in vivo properties. 342 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>