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)

Vitiliginous achromia with malignant melanoma shows some discrepancies with vitiligo. In both achromic and normal skin, four bands A, B, C, D of tyrosinase activity are observed; in vitiligo only bands A and B appear. Ultrastructural findings in achromic skin are similar in both conditions. But in achromia with malignant melanoma, melanocyte abnormalities are also present in normal skin and the role of immunological factors is discussed.
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PMID:Vitiliginous achromia with malignant melanoma. Tyrosinase activity and ultrastructural study of achromic and normal skin. 40 21

A stimulation of the tyrosinase activity was observed when melanoma cells isolated from transplantable mouse melanomas were incubated at 37 degrees C for 6 h in the presence of 1-10 X 10(-6) M alpha-MSH. All strains of mouse melanomas studied (B-16, Cloudman S-91 and Harding-Passey), exhibited similar responses. It was also observed that the intact cellular structure of melanoma cells was not required for the ability to respond to alpha-MSH. The stimulation of the enzymic activity was accompanied by an increase of the rate of incorporation of radioactivity into melanin from L-[U-14C]tyrosine, indicating an enhanced melanogenesis of tumour cells under in vitro conditions.
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PMID:Effect of alpha-MSH on the tyrosinase activity and the rate of melanin accumulation of melanoma cells in vitro. 40 59

A stable phenol, gamma-L-glutaminyl-4-hydroxybenzene (GHB), is oxidized by tyrosinase in the gill tissues of the mushroom Agaricus bisporus to a quinone and a second oxidation product which together suppress mitochondrial energy production and the synthesis of proteins and nucleic acids in the zygote, thus establishing dormancy in the spores. Brief incubation of cultured murine L1210 leukemia and B-16 melanoma cells with muM concentrations of the purified quinone notably prolonged survival times or blocked tumor growth in histocompatible mice inoculated i.p. with high concentrations of the exposed cells. The instability of the quinone precluded in vivo administration. The short incubation of cultured B-16 melanoma cells with mM concentrations of GHB markedly prolonged survival times or abolished tumor growth in histocompatible C57BL/6J mice inoculated i.p. with 5 X 10(6) exposed cells. This response did not occur with L1210 leukemia cells, which lack the enzyme tyrosinase. The survival times of mice bearing B-16 melanoma, but not of those with L1210 leukemia, were slightly prolonged by a single injection and were significantly extended by daily i.p. injections of GHB. Normal C57BL/6J mice, given GHB i.p. as single or multiple 400-mg/kg doses, manifested no systemic toxicity but showed depigmentation of the hair after 2 to 3 weeks. These studies provide evidence that GHB exerts cytotoxicity specifically for cells that by their content of tyrosinase convert the phenol to the quinone. This targeted response minimizes systemic toxocity and underscores the potential therapeutic application of this agent to melanocarcinoma.
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PMID:gamma-L-Glutaminyl-4-hydroxybenzene, an inducer of cryptobiosis in Agaricus bisporus and a source of specific metabolic inhibitors for melanogenic cells. 40

Human malignant melanocytes show characteristic morphologic modifications which are particularly evident in their specific organelles: melanosomes. These modifications are conserved in cell culture. The ultrastructural localization of tyrosinase, the enzyme which converts tyrosine and dopa into melanin, was determined in 13 human melanoma cell lines. The different cell lines possess 4 distribution patterns of melanin synthesis based on dopa oxidase activity. The two first pathways, which involve the Golgi apparatus, seem to differ by the amount of enzyme within this organelle. The third pathway mainly involves the smooth endoplasmic reticulum, whereas tyrosinase is visible only in vesicles in the fourth. Some cells synthesize the enzyme in the manner observed in very early embryos.
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PMID:Cellular localization of tyrosinase in human malignant melanoma cell lines. 40 30

The drug p-hydroxyanisole (OHA) was found to inhibit the incorporation of 3H-thymidine in the Harding-Passey melanoma cells in culture. Because the cultured cells had lost some of their pigment-forming capacity, the enzyme tyrosinase was added to the culture. This greatly increased the sensitivity of the cells to OHA, strongly suggesting that cells producing the enzyme would be preferentially killed by the drug. An in-vivo study of the effect of OHA injected into tumour-bearing mice showed a beneficial effect, including increased survival time, reduction in tumour size and in many cases complete loss of tumour and no recurrence. An experiment with animals immunologically suppressed by radiation suggests that the effect is not an immunological one.
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PMID:Hydroxyanisole-induced regression of the Harding-Passey melanoma in mice. 40 43

A study was made on the effect of Triton X-100 in different concentrations on the tyrosinase activity of two differently pigmented melanosome fractions of pigmented hamster melanoma, obtained by gradient centrifugation. Release of considerable tyrosinase activity was established spectrophotometrically in the supernatant of the treated melanosomes. The release of enzyme activity after treatment of the melanosome is probably due to a change in the permeability of the melanosome structures under the effect of the non-ionic detergent Trition X-100. A direct activating effect of Trition X-100 on the particulate enzyme should be excluded, since inhibition of DOPA-oxidase activity was established in the soluble tyrosinase fraction.
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PMID:Solubilizing effect of Trition X-100 on melanosome tyrosinase in hamster pigmented melanoma. 40 15

Serum tyrosinase activity has been measured by adapting the [3]tyrosine assay for tyrosinase and significant elevations of serum tyrosinase activity were found in patients with malignant melanoma. In contrast to findings in a study which utilized [14C]tyrosine, augmented levels of tyrosinase activity were not observed in sera from patients with other malignancies, including subjects with carcinoma of the breast. The results of the examinations for soluble tyrosinase activity in human malignant melanoma tissue-cultured lines were all positive, whereas human cell lines from carcinoma of the breast, carcinoma of the colon and sarcoma uniformly showed no activity. The method employed for detecting tyrosinase activity holds promise as a specific diagnostic test and may be valuable for monitoring the response to clinical treatment of patients with malignant melanoma.
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PMID:Tyrosinase activity in the sera of patients with malignant melanoma: method and specificity. 41 60

The activity of dominant human melanoma tyrosinase isozyme was greatly decreased by certain reducing agents. The number and geometry of phenolic groups as well as free--SH group appear important for enzymic inhibition.
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PMID:In vitro effects of melanocytolytic agents and other compounds upon dominant human melanoma tyrosinase activity. 41 35

Alteration in DOPA-oxidase activity of Harding-Passey melanoma microsomal fraction tyrosinase, activation of tyrosinase after partial delipidization of the microsome, phospholipid composition of both native microsomes and the ones after delipidization have been studied. In the course of tumor growth (starting on the 14th day after tumor transplantation) the tyrosinase activity has been shown to decrease monotonously both in native microsomes and in the ones after delipidization. The phospholipid composition alters both in the process of tumor growth and after delipidization. Alteration in the tyrosinase activity in native microsomes as well as after their delipidization has been found to depend on the relative composition of certain phospholipids. In those cases a linear correlation between the enzyme activity and the phosphatydylethanolamine of phosphatydylcholine ratio has been found. This interrelationship may be accounted for by either simultenous presence of inhibitors and activators of the enzyme activity in the lipids or by changes in the membrane structure depending on the relative phospholipid composition.
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PMID:[Investigation of tyrosinase activity and phospholipid composition in Harding-Passey melanoma microsomal fraction]. 41 89

The growth inhibitory effect of 6-hydroxydopa, a cytotoxic analog of L-dopa, was studied in melanotic and amelanotic Cloudman melanoma, mouse fibroblast L929 and Chinese hamster ovary cells. A marked sensitivity of pigmented cells to 6-hydroxydopa was observed with a 10-fold increase in sensitivity of pigmented cells. Sensitivity correlated with the capacity of cells to incorporate radiolabeled exogenous L-dopa. The drug affected primarily DNA and RNA synthesis with greater inhibition observed in pigmented cells than the nonpigmented control cells. The mechanism of action may involve interaction with the melanocyte specific enzyme, tyrosinase, as a false substrate.
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PMID:Selective toxicity of 6-hydroxydopa for melanoma cells. 42 70


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