Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.10.3.1 (tyrosinase)
9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interleukin (IL)-1 alpha, IL-6, and tumor necrosis factor (TNF)-alpha are epidermal cytokines that produce many similar biologic effects. We have investigated the possibility that these cytokines act as regulators of melanization and proliferation of cultured normal human melanocytes (NHM). All three cytokines elicited a dose-dependent decrease in the activity of the enzyme tyrosinase after 48 h of treatment. IL-1 alpha had the greatest inhibitory effect, resulting in a 22% inhibition of tyrosinase activity at a concentration of 3 x 10(-14) M. An equivalent effect was elicited by 4 x 10(-11) M IL-6 and 10(-11) M TNF-alpha. All three cytokines also inhibited melanocyte proliferation, as measured by a decrease in the rate of 3H-thymidine incorporation and an increase in doubling time. IL-1 alpha at 6 x 10(-14) M, 6 x 10(-13) M, and 3 x 10(-12) M, TNF-alpha at 10(-10) M, 10(-9) M, and 10(-8) M, and IL-6 at 4 x 10(-10) and 1.2 x 10(-9) M produced a dose-dependent inhibition of 3H-thymidine incorporation. The effects of IL-1 alpha, TNF-alpha, and IL-6 were cytostatic, not cytotoxic, because melanocytes remained viable following several treatments with the cytokines. Also, melanocytes treated with IL-1 alpha and TNF-alpha recovered and resumed proliferation after cessation of treatment. These effects of IL-1 alpha, IL-6 and TNF-alpha do not seem to be mediated by stimulation of eicosanoid production, because inhibition of arachidonic acid (AA) metabolism by indomethacin, a cyclooxygenase inhibitor, and nordihydroguaiaretic acid, a lipoxygenase inhibitor, did not reverse the inhibitory effects on either proliferation or tyrosinase activity of NHM. This is the first demonstration that NHM respond to epidermal cytokines, and suggests a role for paracrine and possibly autocrine regulation of melanocytes by immune modulators.
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PMID:Interleukins 1 alpha and 6 and tumor necrosis factor-alpha are paracrine inhibitors of human melanocyte proliferation and melanogenesis. 189 43

Expression of an extended panel of cytokine genes was investigated by reverse polymerase chain reaction (PCR) in 10 freshly excised melanoma metastases infiltrated by lymphocytes (TIL). cDNA encoding for CD3-delta and tyrosinase could be amplified in all samples, confirming the presence of T lymphocytes and melanoma cells. Cytokine genes possibly transcribed by both cell types, such as GM-CSF, IL-6 and IL-10 could be amplified from 5, 2 and 2 samples respectively. In contrast, IL-1 beta and TNF-alpha mRNA were never detectable, IL-1 alpha, IL-3 and IL-7 mRNA could be observed only in one case each. Transcripts encoding for TGF-beta 1 were observed in 8 samples, while TGF-beta 2 and 3 mRNA were detectable in only 2 specimens. mRNA encoding for cytokine genes typically transcribed by antigen-stimulated T lymphocytes, such as IL-2, IL-4 and IFN-gamma were rarely or never detectable (none, none and 1 of the samples respectively). In one case, where no cytokine gene transcription was detectable at the time of surgery, we addressed the question of the antigenicity of the tumor and of the functional competence of TIL. A primary tumor cell line was generated and cultured TIL were induced to transcribe IL-2 and IFN-gamma genes by incubation with the autologous irradiated tumor cell line, but not with autologous EBV-transformed cells. In these conditions, tumor-specific cytotoxic T lymphocytes (CTL) could be generated only after 3 weekly re-stimulations. In contrast, if autologous irradiated EBV-transformed cells were added to the cultures, specific CTL could be detected after one single tumor stimulation. Thus, signs of active responsiveness in terms of lymphokine gene mRNA are seldom detectable in melanoma metastases. Tumor-specific responses, however, including IL-2 and IFN-gamma gene expression and generation of CTL can be produced in vitro from specimens in which no cytokine gene mRNA is detectable ex vivo.
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PMID:The pattern of cytokine gene expression in freshly excised human metastatic melanoma suggests a state of reversible anergy of tumor-infiltrating lymphocytes. 818 65

A major challenge in the gene therapy of proliferative diseases is the specific targeting of gene expression. Here we describe a new approach based on the development of dual-specificity promoters that are both cell type specific and cell cycle regulated. The gene of interest is driven by an artificial heterodimeric transcription factor, whose DNA-binding subunit is expressed from a tissue-specific promoter, whereas the trans-activating subunit is transcribed from a cell cycle-regulated promoter. As a result gene expression occurs preferentially in the proliferating cells of a specific type of tissue. The selectivity of this strategy is demonstrated for the expression of a transgene in proliferating melanoma cells, using a combination of cyclin A and tyrosinase promoter elements. We also show that the level of expression that can be achieved by this system is sufficient to induce a clear biological effect in a TNF-alpha cytotoxicity assay.
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PMID:Tissue-specific, cell cycle-regulated chimeric transcription factors for the targeting of gene expression to tumor cells. 987 63

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that can be used for vaccination purposes, to induce a specific T-cell response in vivo against melanoma-associated antigens. We have shown that the sequential use of early-acting hematopoietic growth factors, stem cell factor, IL-3 and IL-6, followed by differentiation with IL-4 and granulocyte-macrophage colony-stimulating factor allows the in vitro generation of large numbers of immature DCs from CD34(+) peripheral blood progenitor cells. Maturation to interdigitating DCs could specifically be induced within 24 hr by addition of TNF-alpha. Here, we report on a phase I clinical vaccination trial in melanoma patients using peptide-pulsed DCs. Fourteen HLA-A1(+) or HLA-A2(+) patients received at least 4 i.v. infusions of 5 x 10(6) to 5 x 10(7) DCs pulsed with a pool of peptides including either MAGE-1, MAGE-3 (HLA-A1) or Melan-A, gp100, tyrosinase (HLA-A2), depending on the HLA haplotype. A total of 83 vaccinations were performed. Clinical side effects were mild and consisted of low-grade fever (WHO grade I-II). Clinical and immunological responses consisted of anti-tumor responses in 2 patients, increased melanoma peptide-specific delayed-type hypersensitivity reactions in 4 patients, significant expansion of Melan-A- and gp100-specific cytotoxic T lymphocytes in the peripheral blood lymphocytes of 1 patient after vaccination and development of vitiligo in another HLA-A2(+) patient. Our data indicate that the vaccination of peptide-pulsed DCs is capable of inducing clinical and systemic tumor-specific immune responses without provoking major side effects.
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PMID:Phase I study in melanoma patients of a vaccine with peptide-pulsed dendritic cells generated in vitro from CD34(+) hematopoietic progenitor cells. 1076 Aug 27

Our study demonstrates that tumor-derived heat shock protein (HSP)70 chaperones a tyrosinase peptide and mediates its transfer to human immature dendritic cells (DCs) by receptor-dependent uptake. Human tumor-derived HSP70 peptide complexes (HSP70-PC) thus have the immunogenic potential to instruct DCs to cross-present endogenously expressed, nonmutated, and tumor antigenic peptides that are shared among tumors of the melanocytic lineage for T cell recognition. T cell stimulation by HSP70-instructed DCs is dependent on the Ag bound to HSP70 in that only DCs incubated with HSP70-PC purified from tyrosinase-positive (HSP70-PC/tyr(+)) but not from tyrosinase-negative (HSP70-PC/tyr(-)) melanoma cells resulted in the specific activation of the HLA-A*0201-restricted tyrosinase peptide-specific cytotoxic T cell clone. HSP70-PC-mediated T cell stimulation is very efficient, delivering the tyrosinase peptide at concentrations as low as 30 ng/ml of HSP70-PC for T cell recognition. Receptor-dependent binding of HSP70-PC and active cell metabolism are prerequisites for MHC class I-restricted cross-presentation and T cell stimulation. T cell stimulation does not require external DC maturation signals (e.g., exogenously added TNF-alpha), suggesting that signaling DC maturation is an intrinsic property of the HSP70-PC itself and related to receptor-mediated binding. The cross-presentation of a shared human tumor Ag together with the exquisite efficacy are important new aspects for HSP70-based immunotherapy in clinical anti-cancer vaccination strategies, and suggest a potential extension of HSP70-based vaccination protocols from a patient-individual treatment modality to its use in an allogeneic setting.
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PMID:Tumor-derived heat shock protein 70 peptide complexes are cross-presented by human dendritic cells. 1242 17

High mortality rate for metastatic melanoma is related to its resistant to the current methods of therapy. Melanogenesis is a metabolic pathway characteristic for normal and malignant melanocytes that can affect the behavior of melanoma cells or its surrounding environment. Human melanoma cells in which production of melanin pigment is dependent on tyrosine levels in medium were used for experiments. Peripheral blood mononuclear cells were derived from the buffy coats purchased from Lifeblood Biological Services. Cell pigmentation was evaluated macroscopically, and tyrosinase activity was measured spectrophotometrically. Cell proliferation and viability were measured using lactate dehydrogenase release MTT, [(3)H]-thymidine incorporation and DNA content analyses, and gene expression was measured by real time RT-PCR. Pigmented melanoma cells were significantly less sensitive to cyclophosphamide and to killing action of IL-2-activated peripheral blood lymphocytes. The inhibition of melanogenesis by either blocking tyrosinase catalytic site or chelating copper ions sensitized melanoma cells towards cytotoxic action of cyclophosphamide, and amplified immunotoxic activities of IL-2 activated lymphocytes. Exogenous L-DOPA inhibited lymphocyte proliferation producing the cell cycle arrest in G1/0 and dramatically inhibited the production of IL-1beta, TNF-alpha, IL-6 and IL-10. Thus, the active melanogenesis could not only impair the cytotoxic action of cyclophosphamid but also has potent immunosuppressive properties. This resistance to a chemotherapeutic agent or immunotoxic activity of lymphocytes could be reverted by the action of tyrosinase inhibitors. Thus, the inhibition of melanogenesis might represent a valid therapeutic target for the management of advanced melanotic melanomas.
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PMID:Inhibitors of melanogenesis increase toxicity of cyclophosphamide and lymphocytes against melanoma cells. 1908 34

In the present article, we have synthesized a combinatorial library of 3,5-diaryl pyrazole derivatives using 8-(2-(hydroxymethyl)-1-methylpyrrolidin-3-yl)-5,7-dimethoxy-2-phenyl-4H-chromen-4-one (1) and hydrazine hydrate in absolute ethyl alcohol under the refluxed conditions. The structures of the compounds were established by IR, (1)H NMR and mass spectral analysis. All the synthesized compounds were evaluated for their anticancer activity against five cell lines (breast cancer cell line, prostate cancer cell line, promyelocytic leukemia cell line, lung cancer cell line, colon cancer cell line) and anti-inflammatory activity against TNF-alpha and IL-6. Out of 15 compounds screened, 2a and 2d exhibited promising anticancer activity (61-73% at 10 microM concentration) against all selected cell lines and IL-6 inhibition (47% and 42% at 10 microM concentration) as in comparison to standard flavopiridol (72-87% inhibition at 0.5 microM) and dexamethasone (85% inhibition at 1 microM concentration), respectively. Cytotoxicity of the compounds checked using CCK-8 cell lines and found to be nontoxic to slightly toxic. Out of 15, four 3,5-diaryl pyrazole derivatives exhibiting potent inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase. The IC(50) values of compounds (2a, 2d, 2h and 2l) for monophenolase inhibition were determined to range between 1.5 and 30 microM. Compounds 2a, 2d, 2h and 2l also inhibited diphenolase significantly with IC(50) values of 29.4, 21.5, 2.84 and 19.6 microM, respectively. All four 3,5-diaryl pyrazole derivatives were active as tyrosinase inhibitors (2a, 2d, 2h and 2l), and belonging to competitive inhibitors. Interestingly, they all manifested simple reversible slow-binding inhibition against diphenolase.
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PMID:Synthesis of novel 3,5-diaryl pyrazole derivatives using combinatorial chemistry as inhibitors of tyrosinase as well as potent anticancer, anti-inflammatory agents. 2063 87

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