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)

It is known that many immunologic responses to IL-1 are antagonized by the neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH). This led us to investigate the possible reciprocal effects of IL-1 and the functionally related epidermal cytokines, epidermal cell-derived thymocyte activating factor (ETAF) and IL-6, on the melanogenic effect of alpha-MSH on murine Cloudman melanoma cells. When these cells were treated with ETAF in combination with alpha-MSH or its potent analog [Nle4,D-Phe7]-alpha-MSH, the melanotropin induced increase in tyrosinase activity, and thus melanin synthesis, was abrogated. This inhibitory effect of ETAF was not mediated by competitive binding to the melanotropin receptor, because ETAF also blocked the melanogenic response of melanoma cells to isobutyl methylxanthine (IBMX) and to PGE1 and PGE2. ETAF had no effect on cellular proliferation. Inhibition of the stimulated tyrosinase activity by ETAF was not due to diminished cAMP synthesis or increased cAMP degradation. Cells treated concomitantly with ETAF and alpha-MSH, IBMX, or PGE1 had the same cAMP levels as cells treated with alpha-MSH, IBMX, or PGE1 alone. In contrast to ETAF, human rIL-1 alpha or IL-1 beta alone or in combination did not have an inhibitory effect on melanogenesis. IL-6 significantly inhibited the basal level of tyrosinase and partially abrogated the alpha-MSH-induced tyrosinase activity. IL-6 also stimulated cellular proliferation when added alone or in combination with alpha-MSH. Granulocyte-macrophage colony stimulating factor (GM-CSF) did not alter either the tyrosinase activity or cellular replication at the concentrations tested. IL-1 alpha, GM-CSF, and IL-6 or IL-1 alpha and GM-CSF added together did not significantly affect the MSH-induced tyrosinase activity. These results ascribe a new potential function for ETAF and IL-6 as modulators of the melanogenic response of pigment cells.
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PMID:A new role for epidermal cell-derived thymocyte activating factor/IL-1 as an antagonist for distinct epidermal cell function. 246 81

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

Peptide epitopes derived from differentiation antigens of the melanocyte lineage were recently identified in human melanomas as targets for MHC-restricted cytotoxic T lymphocytes (CTL). The characterization of multiple CTL-defined antigenic determinants has opened possibilities of development of antigen-targeted vaccines. In the present study, we determined CTL reactivity against melanoma-associated peptides derived from Melan A/MART-1, tyrosinase, and gp100/Pmel17 in 3 HLA-A2+ melanoma patients. Then, we assessed the immune responses to synthetic melanoma-associated peptides injected intradermally. After 3 cycles of immunization with peptide alone, we used systemic GM-CSF as an adjuvant during the fourth cycle of immunization. Enhanced DTH reactions and CD8+ CTL responses were observed after treatment with systemic GM-CSF. Immunohistochemical characterization of DTH-constituting elements revealed infiltrates of CD4+ and CD8+ T lymphocytes and strong expression of IL-2 and gammaIFN, suggesting the activation of CD4+ ThI and CD8+ CTL by peptides presented by MHC-class-I molecules of dermal APC. Objective tumor regression was documented in all patients. We conclude that systemic GM-CSF enhances immune responses to melanoma-associated peptides and supports CTL-mediated tumor rejection in vivo.
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PMID:Granulocyte-macrophage-colony-stimulating factor enhances immune responses to melanoma-associated peptides in vivo. 869 May 25

Sixteen patients with metastatic stage IV melanoma were treated with use of intravenous infusions of dendritic cells (DC) derived by incubation of plastic-adherent peripheral blood mononuclear cells (PBMC) with IL-4 and GM-CSF for 8 days in serumless AIM-V medium, followed by overnight pulsing with peptides. The tyrosinase368-376 (370D) and gp100(209-217 (210M)) peptides restricted to HLA class I A*0201 each differed from wild type by one amino acid modified to increase HLA binding. Median age was 49, with nine men and seven women. All patients, except one, had visceral disease. Patients received escalating doses of peptide-pulsed DCs at 10e7, 3 x 10e7, and 10e8 cells/dose twice at 2 weeks apart, with toxicity and clinical and immune responses as the principal endpoints. The first infusion of DCs was fresh, and frozen DCs were given for the second infusion of each cycle. Mean DC purity by flow cytometry was 49%, with a mean HLA-DR level of 57%, CD86 of 41%, CD58 of 46%, and mean CD14 cells of 0.9%. Toxicity was minimal, with two patients having transient grade III DC-related toxicity. Ten patients received one cycle of treatment and six patients received two cycles of treatment. One patient had a complete remission (CR) of lung and pleural disease after two cycles of DC therapy. Two additional patients had stable disease and two patients had mixed responses. Overall immunity was assessed by recall skin testing with peptides, gamma interferon ELISA assays of peptide specific cytolytic T cell (CTL) stimulated twice with peptide, IL-2, and IL-7 over 24 days, and peptide-specific tetramer assays performed before and after vaccination. Five of 16 patients had an immune response to gp100 or tyrosinase by gamma interferon ELISA assay; four of five were clinically stable or had tumor regression. These data suggest that melanoma antigen peptide-pulsed DC given intravenously are not toxic, and regression or stability of tumor appeared to correlate with the detection of a peptide-specific immune response in the peripheral blood.
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PMID:Phase I trial of intravenous peptide-pulsed dendritic cells in patients with metastatic melanoma. 1121 Nov 50

Many peptide epitopes for cytotoxic T lymphocytes (CTLs) have been identified from melanocytic differentiation proteins. Vaccine trials with these peptides have been limited mostly to those associated with HLA-A2, and immune responses have been detected inconsistently. Cases of clinical regression have been observed after peptide vaccination in some trials, but melanoma regressions have not correlated well with T-cell responses measured in peripheral blood lymphocytes (PBLs). We vaccinated stage IV melanoma patients with a mixture of gp100 and tyrosinase peptides restricted by HLA-A1 (DAEKSDICTDEY), HLA-A2 (YLEPGPVTA and YMDGTMSQV) and HLA-A3 (ALLAVGATK) in an emulsion with GM-CSF and Montanide ISA-51 adjuvant. CTL responses were assessed in PBLs and in a lymph node draining a vaccine site (sentinel immunized node, SIN). We found CTL responses to vaccinating peptides in the SIN in 5/5 patients (100%). Equivalent assays detected peptide-reactive CTLs in PBLs of 2 of these 5 patients (40%). CTLs expanded from the SIN lysed melanoma cells naturally expressing tyrosinase or gp100. We demonstrated immunogenicity for peptides restricted by HLA-A1 and -A3 and for 1 HLA-A2 restricted peptide, YMDGTMSQV. Immune monitoring of clinical trials by evaluation of PBLs alone may under-estimate immunogenicity; evaluation of SIN provides a new and sensitive approach for defining responses to tumor vaccines and correlating these responses with clinical outcomes. This combination of an immunogenic vaccine strategy with a sensitive analysis of CTL responses demonstrates the potential for inducing and detecting anti-tumor immune responses in the majority of melanoma patients.
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PMID:Evaluation of peptide vaccine immunogenicity in draining lymph nodes and peripheral blood of melanoma patients. 1134 May 76

Members of the heat shock protein (hsp70) family are either constitutively expressed (hsc70) or can be induced by hyperthermic stress (hsp70). Recombinant hsp70 (rhsp70) stimulates cytokine production from monocytes and enhances NK cell proliferation and cytotoxicity. Here we demonstrate that rhsp70 binds to immature dendritic cells (DC) derived from monocyte precursors and induces their maturation as evidenced by an increase in CD40, CD86 and CD83 expression. Immature DC stimulated to mature with rhsp70 show an enhanced ability to present tyrosinase peptide to specific CTL. Mature DC did not bind rhsp70, suggesting a down-regulation in the expression of its receptor. When rhsp70 was added to monocyte precursors at the same time as GM-CSF and IL-4 it reduced the differentiation of monocytes into DC as shown by a decrease in the level of CD40, CD83, CD86 and HLA-DR expression and an increase in CD14 expression. The constitutively expressed hsc70 had neither a stimulatory effect on the maturation of immature DC nor did it reduce the differentiation of monocytes into DC. These findings demonstrate the specific ability of rhsp70 to induce the maturation of immature DC. Therefore rhsp70 may be useful for its adjuvant like properties in DC based immunotherapy of certain tumors.
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PMID:The role of heat shock protein (hsp70) in dendritic cell maturation: hsp70 induces the maturation of immature dendritic cells but reduces DC differentiation from monocyte precursors. 1146 18

We have previously shown that small B16 melanomas can be successfully treated using a combination of anti-cytotoxic T lymphocyte antigen (CTLA)-4 monoclonal antibody with a granulocyte/macrophage colony-stimulating factor (GM-CSF) producing irradiated tumor cell vaccine. Regression of tumors results in long-lasting immunity and is frequently accompanied by autoimmune depigmentation. Here we examine the cellular and molecular mechanisms of this combined treatment. Histological examination of depigmented lesions revealed infiltration of polymorphonuclear cells and deposition of antibody. The combination therapy also induced tumor rejection and skin depigmentation in B cell-deficient and in CD4(+) T cell-depleted mice. Both effects of the treatment absolutely required CD8(+) T cells. Analysis of the response in successfully treated mice revealed elevated levels of CD8(+) T cells specific for a nonameric peptide consisting of residues 180-188 of the melanocyte differentiation antigen tyrosinase-related protein (TRP)2. There was no evidence of reactivity to the melanocyte antigens gp100, tyrosinase, Mart1/MelanA, or TRP1. Fas-FasL interactions and perforin played a role in mounting the effector response, whereas the tumor necrosis factor pathway was not required. The cellular requirements for tumor rejection in this therapeutic setting were strikingly different from those in a prophylactic setting. In particular, if mice received a prophylactic vaccine consisting of anti-CTLA-4 and B16-GM-CSF before tumor challenge, full protection was obtained even in the absence of CD8(+) T cells. Our data demonstrate that therapeutic autoreactive CD8(+) T cell responses can effectively be generated in tumor-bearing mice and stresses the value of studying tumor immunity in a therapeutic rather than a prophylactic setting.
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PMID:Elucidating the autoimmune and antitumor effector mechanisms of a treatment based on cytotoxic T lymphocyte antigen-4 blockade in combination with a B16 melanoma vaccine: comparison of prophylaxis and therapy. 1151 4

We report here on 2 patients who received adjuvant vaccination with an HLA-A2- or HLA-A24-restricted tyrosinase peptide, respectively, and GM-CSF for frequently relapsing stage IV melanoma. Following resection of metastases and irradiation of brain metastases in 1 patient, both patients were without evidence of disease when receiving the first vaccination. While the patients had had 9 and 12, respectively, mostly s.c., relapses during the 3 years before vaccination, they experienced freedom from relapse for more than 2 years after vaccination. We found a T-cell response to the vaccine peptide in both patients in the peripheral blood by ex vivo IFN-gamma ELISPOT assay. The T-cell population could be further characterized by 4-color flow cytometry in 1 patient, showing that the majority of the peptide-specific CD3(+)CD8(+)IFN-gamma(+) T cells were granzyme B-positive and CCR-7-negative, characterizing them as effector T cells with the ability to mediate cytotoxicity and migrate to inflamed tissues. In this patient also, augmentation of the T-cell response to autologous tumor cells by vaccination could be detected. A single-site postvaccination relapse occurred in both patients, showing downregulation of tyrosinase expression in 1 patient, while normal expression levels for tyrosinase, MHC class I antigens and components of the antigen-processing machinery were found in the other patient. These results suggest that peptide vaccination resulted in a prolonged relapse-free interval in these high-risk patients.
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PMID:Long-term freedom from recurrence in 2 stage IV melanoma patients following vaccination with tyrosinase peptides. 1199 9

We conducted a randomized trial in HLA*A0201+ patientswith American Joint Committee on Cancer stage III or IV melanoma immunized with tyrosinase 368-376(370D) peptide and gp100 209-217(210M) peptide to compare the potency of three different adjuvants. Patients received 3 monthly immunizations with 500 microg of each peptide either with incomplete Freund's adjuvant (IFA), QS-21, or granulocyte macrophage colony-stimulating factor (GM-CSF). The primary end point was induction of IFN-gamma release by CD8+ T cells against tyrosinase and gp100 peptides measured by enzyme-linked immunospot assays without in vitro prestimulation measured pretreatment, 2 and 8 weeks after the third vaccination. Four of 9 and 4 of 8 patients immunized using QS-21 and GM-CSF, respectively, developed increased frequencies of CD8+ T cells against tyrosinase 370D peptide compared with 0 of 9 patients immunized using IFA (P = 0.045). T-cell responses against a gp100-related peptide showed similar results, but their relevance to T-cell reactivity against native gp100 209-217 is uncertain. These results show that: (a) QS-21 and GM-CSF are superior to IFA as immunological adjuvants for vaccination against tyrosinase 370D peptide; and (b) with appropriate adjuvants, increased frequencies of peptide-specific T cells after vaccination can be detected by enzyme-linked immunospot without prolonged prestimulation in vitro.
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PMID:T-cell responses against tyrosinase 368-376(370D) peptide in HLA*A0201+ melanoma patients: randomized trial comparing incomplete Freund's adjuvant, granulocyte macrophage colony-stimulating factor, and QS-21 as immunological adjuvants. 1200 8

In an ongoing phase I/II study, metastatic melanoma patients were treated with a replication-incompetent recombinant vaccinia virus (rVV) encoding Melan-A(27-35), gp100(280-288), and tyrosinase(1-9) HLA-A*201-restricted epitopes together with B7.1 and B7.2 co-stimulatory molecules. rVV was administered in the context of systemic GM-CSF treatment. Boosts were subsequently administered 2 weeks apart with corresponding synthetic nonapeptides and GM-CSF. Two cycles of treatment were administered 2 weeks apart from each other. Specific immune responses were evaluated by quantitative assessment of cytotoxic T-lymphocyte precursor frequency and tetramer staining. By the time the two cycles had been completed, four out of five patients showed significant (greater than threefold) increases in gp100(280-288)-specific and four out of five, in Melan-A(27-35)-specific tetramer staining of CD8+ cells. Frequencies of CTL precursors specific for gp100(280-288), tyrosinase(1-9) and Melan-A(27-35) were also significantly increased in all five, and in four and four of the five patients, respectively, in some cases within 12 days after the first injection of the recombinant vector. Thus, the innovative vector under investigation is able to raise a concurrent and specific cellular immune response against a panel of molecularly defined antigens, thereby increasing the chance of an immune hit against neoplastic cells displaying heterogeneous antigen expression.
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PMID:Cytotoxic T-cell induction in metastatic melanoma patients undergoing recombinant vaccinia virus-based immuno-gene therapy. 1207 14


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