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

Tyrosine hydroxylase, dopa oxidase, and peroxidase activities were studied in soluble fractions of B16 melanoma tumor homogenates by polyacrylamide gel disc electrophoresis. Stained gels were scanned photometrically and gel slices were assayed radiometrically. In these preparations, the two bands of tyrosine hydroxylating activity were completely separated from the peroxidase activity but coincided with two major bands of dopa oxidase activity. The third dopa oxidase band coincided with the single band of peroxidase activity. The soluble fraction of cultured cell homogenates had no peroxidase activity, but the two tyrosine hydroxylase bands coincided exactly with the two dopa oxidase bands. Therefore, in the soluble fraction of the murine melanoma bifunctional tyrosinase does exist as two electrophoretically separable forms which are independent of peroxidase.
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PMID:Characteristics of tyrosinase in B16 melanoma. 1 62

To identify soluble cell surface melanoma-associated antigens (MAA), human melanoma cells in culture were radioiodinated by the lactoperoxidase technique and solubilized in non-ionic detergent (NP-40). Labelled MAA were identified by a quantitative double-antibody antigen binding assay and unrelated labelled macromolecules by trichloroacetic acid precipitation. Detergent solubilized 95% of the macromolecule-associated radioactivity. Approximately 8%, presumably MAA, was bound specifically by anti-melanoma serum. In contrast, anti-melanoma serum bound specifically only 0.5 to 1.5% of the acid precipitable radioactivity in control cells iodinated in a similar manner. Specificity was further studied by quantitative serum absorption. Two different melanoma lines were equally effective in inhibiting specific binding of iodinated melanoma lysate, whereas 50-100 times more normal fresh lymphocytes, liver and spleen cells, cultured HeLa or colon adenocarcinoma cells, and 8 times more cultured fetal cells were required to produce similar reductions in specific binding. These studies demonstrate that cell surface human melanoma antigens that differ qualitatively and/or quantitatively from those on normal or malignant allogeneic tissues can be solubilized and identified. These antigens are shared with other melanomas, and some are also present on fetal cells.
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PMID:Identification and solubilization of iodinated cell surface human melanoma associated antigens. 7 Apr 12

Biochemical characterization of serologically detected human melanoma antigens was undertaken for the development of immunodiagnostic assays in melanoma. An antiserum from a human melanoma patient, which detected melanoma antigens expressed on a large proportion of different melanoma cells, was used in leucocyte-dependent cytotoxic antibody (LDA) 51Cr-release assays to monitor the purification of melanoma antigens in urea/acetate extracts of lactoperoxidase 125I-labelled melanoma cell membranes. The separation procedures included affinity chromatography on Concanavalin A, gel filtration on porous polyacrylamide beads and preparative isoelectric focusing. The fractions were also monitored by polyacrylamide electrophoresis in sodium dodecyl sulphate and by measurement of beta 2 microglobulin and carcinoembryonic antigen content. The antigens detected by this antiserum appeared to be acidic (pI 3.5) low-mol.-wt glycoproteins of approximately 15,000 daltons which were resistant to heating at 56 degrees C and digestion with neuraminidase, but susceptible to repeated freeze-thawing and trypsin digestion. They did not appear to be related to HLA antigens, beta 2 microglobulin or known foetal antigens. The nature of the antigens detected in these studies is as yet unknown, but they appear similar to those described in the sera and urine of melanoma patients in previous reports. Thes combined results and the frequent expression of these antigens on melanoma cells from different patients suggest that assays to detect this antigen may provide a valuable immunodiagnostic aid in the management of melanoma.
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PMID:Detection of a low-molecular-weight antigen on melanoma cells by a human antiserum in leukocyte-dependent antibody assays. 9 79

Several in vitro properties of two variant cell lines of the B16 melanoma (B16-F10 and B16-BL6) with markedly different spontaneous metastatic behavior were examined. The two cell lines were compared with regard to their in vitro growth rate, ability to migrate, ability to adhere to a variety of substrata, detachment rates, production of plasminogen activator, and cell surface proteins as determined by lactoperoxidase-catalyzed iodination. Growth rates in vitro, attachment rates, and qualitative patterns of cell surface proteins were almost identical. B16-F10 cells (the less spontaneously metastatic line) produced greater amounts of plasminogen activator, were more motile in vitro, and detached more readily from plastic than the more invasive B16-BL6 cells. The study of tumor cell variants, selected for different biologic behavior, is a valuable approach to the elucidation of those mechanisms responsible for their malignant activity.
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PMID:The selection and characterization of an invasive variant of the B16 melanoma. 50 92

The hypothesis that the growth of mammalian cells is regulated by hormones is now supported by considerable evidence. Two rat pituitary cell lines, GH3 and GC, a mouse melanoma, M2R (B16), and a human cervical carcinoma cell, HeLa S-3, have been grown indefinitely in serum-free (SF) hormone-supplemented medium. No visible changes of growth characteristics were observed in the cells grown continuously in the SF condition. However, changes in the activity of a plasma membrane enzyme, alkaline phosphatase, and in the relative intensity of surface proteins that are labeled by the [125I] lactoperoxidase technique were found in HeLa cells grown in the SF condition. To study the role of hormones required in the regulation of cell growth, HeLa cells were grown in the absence of one of the required hormones. The following results were obtained. Epidermal growth factor is probably involved in the regulation of the synthesis of macromolecules such as RNA and of the protein content per cell. Transferrin, the accessory factor in the SF condition, supplies iron for cells. The two basic peptides in this SF system, fibroblast growth factor and insulin, are probably involved in the balance of nutrients and energy inside the cell. The replacement of F12 medium with a better-balanced medium, MCDB 105, can mimic the requirements for these two peptides. The steroid hydrocortisone (HC) is probably involved in alteration of the cell surface. This is indicated by the effects of HC on cell morphology, rate of detachment from the dish, and the pattern of [125I] lactoperoxidase labeling of surface proteins. In addition, it is necessary to change the medium more frequently to maintain the culture in the medium without HC. This observation suggests that HC may be involved in the control of homeostatic properties of the cell surface. The production of rat prolactin by GH3 cells was also studied. GH3 cells in the SF condition produce 1.6 microgram prolactin per 10(5) cells in 24 h, while 2.4 microgram is produced in the presence of serum. Prolactin production in the SF condition is enhanced by the presence of thyrotropin-releasing hormone and inhibited by triiodothyronine (T3). T3 is the major growth factor for these cells. Without it cell growth is severely limited, while prolactin production is elevated. This result suggests that the GH3 cell line in the SF condition may be an ideal system for the study of hormonal regulation of cell growth and specific gene expression.
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PMID:Replacement of serum in cell culture by hormones: a study of hormonal regulation of cell growth and specific gene expression. 66 Jun 66

The possibility that peroxidase is functional in melanogenesis in the murine S-91 melanoma has been investigated. It was found that, as in the normal mouse, tyrosinase is the enzyme responsible for the bulk of melanin formation in the malignant melanocyte. Tyrosinase was capable of utilizing tyrosine as a substrate, as well as dopa, although the Vmax with dopa was much higher than with tyrosine. Conversely, the affinity of the enzyme for tyrosine is higher than for dopa, and this relationship may in part be responsible for the occasional misinterpretation of the functional capability of this enzyme.
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PMID:Involvement of tyrosinase in melanin formation in murine melanoma. 80 29

A radioimmune assay for the antitumor agent, macromomycin, using purified, radioiodine-labeled macromomycin and antisera raised in rabbits against a carbodiimide-catalyzed macromycin-Limulus polyphemus hemocyanin complex has been developed. Radiolabeled macromomycin was prepared by direct iodination of the polypeptide antibiotic with the use of iodine monochloride or solid-state lactoperoxidase. Antibody-bound drug was isolated from free macromomycin with dextran-coated, activated charcoal. The standard curve of the sequential saturation assay was linear on a logit-log plot and indicated a lower limit of sensitivity of approximately 100 pg macromomycin. The radioimmune assay was suitable for measuring macromomycin in the presence of other antitumor drugs, and detection of macromomycin was quantitative when it was added to normal human serum or urine. Drug binding to melanoma and mammary carcinoma cell surfaces could be inhibited by preincubating macromomycin with affinity-purified antimacromomycin antibodies. However, once the drug was bound to cell surfaces, addition of antimacromomycin antibodies did not result in removal of the drug from cell surfaces or in reversal of macromomycin-induced inhibition of thymidine incorporation into cellular DNA. Antimacromovide useful tools for developing pharmacokinetic and toxicity studies of macromomycin, as well as for analyzing the mechanism(s) of action of the drug.
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PMID:Radioimmune assay and characteristics of antibodies to macromomycin (NSC 170105). 84 45

In the skin infiltrate of superficial spreading melanoma, non phagocytosing mononuclear cells (NPMC) represent a major cell component. The number of NPMCs decreases as a function of tumour progression. In addition, when an NPMC is in contact with a malignant melanocyte, the latter cell exhibits ultrastructural degenerative changes. In the blood of healthy donors and of melanoma patients, atypical mononuclear cells (AMC) can be identified. AMCs have been shown to participate in antibody-dependent cellular cytotoxicity (ADCC) reactions against melanoma cells in vitro. In this paper, it is reported that NPMCs and AMCs have in common their size, and some ultrastructural features such as indented nuclei, dispersed organelles, rough endoplasmic reticulum profiles and surface microvilli. The two cell types are negative for non-specific esterase. They also fail to react for peroxidase at either the light or the electron microscopic level. They do not adhere to glass. AMCs do not form spontaneous E rosettes, they have no surface IgG and they have no receptors for complement. However, they do form rosettes with EAIgG. On frozen sections firm binding of EAIgG has been seen on the skin infiltrate in three cases out of 10. It is concluded that NPMCs might react with tumour cells in vivo, in the same manner as do AMCs in vitro.
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PMID:Characterization of the mononuclear cell infiltrate in human malignant melanoma. 117 96

Expression of apical cell surface proteins and glycoproteins was examined in polarized primary cultures of mouse uterine epithelial cells (UEC). Lectin-gold cytochemistry revealed that wheat germ agglutinin (WGA) bound specifically to the components of the apical glycocalyx as well as intracellular vesicles. Double labeling with the pH sensitive dye 3-(2,4-dinitroanilino)-3'amino-N-methyldipropylamine (DAMP) demonstrated the acidic nature of the WGA-staining intracellular vesicles. The enzymatic and chemical sensitivities of the WGA binding sites on the apical cell surface were monitored both by WGA-gold staining as well as by 125I-WGA binding assays. In thin sections, a large fraction of these sites were removed by pronase; however, application of a wide variety of proteases, glycosidases, or chemical treatments to the apical surface of intact UEC failed to reduce WGA binding. In no case did treatments designed to remove sialic acids reduce 125I-WGA binding more than 12%. In contrast, endo-beta-galactosidase as well as a combination of beta-galactosidase with beta-hexosaminidase succeeded in removing 28% and 77% of these sites, respectively. These studies suggested that the majority of the apically disposed WGA binding sites involved N-acetylglucosamine residues rather than sialic acids and included lactosaminoglycans. Many of the proteins detected at the apical cell surface by lactoperoxidase-catalyzed radioiodination were WGA-binding glycoproteins. A major class of these glycoproteins displayed Mr > 200 kDa by SDS-PAGE and was heavily labeled metabolically by 3H-glucosamine or by vectorial labeling at the apical cell surface with galactosyl transferase and UDP-3H-galactose. Analyses of the 3H-labeled oligosaccharides labeled by either procedure indicated that a large fraction of the apically disposed WGA-binding oligosaccharides consisted of neutral, O-linked mucin-type structures with median MW of approximately 1,500. Oligosaccharides in this fraction were partially (15%) sensitive to endo-beta-galactosidase digestion and bound to Datura stramonium agglutinin (68%), demonstrating the presence of lactosaminoglycan sequences. UEC were an extremely effective barrier to attachment or invasion by either a highly invasive melanoma cell line, B16-BL6, or implantation-competent mouse blastocysts. In contrast, neither uterine stromal cells nor a non-polarizing UEC cell line, RL95, prevented B16-BL6 attachment.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:WGA-binding, mucin glycoproteins protect the apical cell surface of mouse uterine epithelial cells. 129 97

Here we demonstrate a nonradioactive immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) technique which replaces the standard practice of isotopic protein labeling by iodination or metabolic tagging in the analysis of membrane proteins. The technique has proved extremely valuable in the biochemical analysis of small quantities of frozen, pathological tissue. Membranes were prepared from Dx3 (a human melanoma cell line), C6 (a rat glial cell line), and osteoclastoma (a human giant cell tumor of bone). The membranes were labeled with biotin and immunoprecipitated with a variety of antibodies to the vitronectin receptor (VNR). The VNR proteins were resolved by SDS-PAGE and immunoblotted onto nitrocellulose paper. The biotinylated protein was visualized using streptavidin horseradish peroxidase and enhanced chemiluminescence (ECL). Film exposures ranged from 15 min to 16 h. Good visualization of the VNR, yielding the typical heterodimeric receptor of 90 and 150 kDa, was given. Signals generated were high and background noise low with a 30-min film exposure. An overnight exposure increased the detection of weaker bands. In conclusion, biotinylation of membrane proteins proved a satisfactory label for immunoprecipitation and SDS-PAGE analysis. The ECL development stage was extremely flexible with visualization of strong and weak signals. The method has several advantages over a conventional radioactive immunoprecipitation in that it is relatively inexpensive, simple, quick and nonhazardous.
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PMID:A nonradioactive biochemical characterization of membrane proteins using enhanced chemiluminescence. 144 97


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