Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have shown that the phorbol ester tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates phagocytic leukocytes to produce reactive oxygen intermediates in vitro. The present studies focused on the production of reactive oxygen intermediates by peripheral blood leukocyte cell populations following in vivo exposure of murine epidermis to TPA. TPA induced a dose-dependent (0.2-20 micrograms) increase in polymorphonuclear cells (PMN) that appeared to be recruited from the marginal pools, while simultaneously decreasing the number of peripheral blood mononuclear cells. These alterations were detected as early as 2 h following topical application of TPA and persisted over a 21 day time period, using a twice-weekly TPA treatment schedule. The oxidation of 2',7'-dichlorofluorescin (DCFH) was used to examine the hydroperoxide production in peripheral blood PMN isolated from SENCAR mice treated with TPA. TPA stimulated a 2-fold increase in PMN-associated DCFH oxidation (645.4 +/- 118 fmol DCF) 4 h after topical application of 10 micrograms TPA when compared to PMN isolated from acetone-treated mice (339.0 +/- 35.8 fmol DCF). These observations suggest that topical application of TPA recruits PMN that are activated prior to their infiltration into the epidermis. Given the ability of these cells to migrate to local sites, they may serve as a primed cell population that significantly contributes to cutaneous alterations observed during acute and chronic inflammation following TPA exposure.
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PMID:Enhanced hydroperoxide production by peripheral blood leukocytes following exposure of murine epidermis to 12-O-tetradecanoylphorbol-13-acetate. 198 87

To determine whether oxidants capable of DNA modification are produced by cells treated with tumor promoters, we adapted a fluorometric method to our needs. HeLa cells were preincubated with 2',7'-dichlorofluorescin diacetate (DCFdAc), treated with various agents, sonicated, centrifuged and fluorescence of the oxidized product (DCF) was determined in supernatants. When cells were exposed to H2O2 in the presence of azide (catalase inhibitor) or o-phenanthroline (a lipophilic Fe chelator), an increase in fluorescence was observed. These results show that some Fe ions were interacting with the H2O2 which entered the cells, thus decreasing its levels available for oxidation of the substrate and potentially increasing formation of .OH, known DNA-damaging species. Glutathione (GSH), which is present in cells in substantial amounts, was found to reduce DCF whereas azide counteracted GSH-mediated reduction. Treatment of HeLa cells with 12-0-tetradecanoyl-phorbol-13-acetate (TPA) in the presence of DCFdAc and azide resulted in dose- and time-dependent formation of DCF. Even when cells were sonicated prior to incubation with TPA, DCF was formed at levels proportional to the number of cells as well as dose of TPA. Flow cytometry of TPA-treated cells confirmed these findings. These results demonstrate that tumor promoters can cause oxidative activation of HeLa cells, which produce active oxygen species, most likely H2O2, that ultimately contribute to the formation of oxidized bases such as 5-hydroxymethyl uracil in cellular DNA. They also show that this fluorometric method can be utilized for determination of cellular H2O2 formation at nM concentrations.
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PMID:Hydrogen peroxide formation by cells treated with a tumor promoter. 206 Aug 51

The combined effects of Mitomycin C (MMC) with alpha-interferon (HLBI) or gamma-interferon (TRP-2), which have become attractive drugs for use as Biological Response Modifiers, were investigated using the human tumor clonogenic assay technique. Tumors in this study were five human tumor xenografts serially transplanted into nude mice (three gastric cancer, two colon cancer). When the survival fraction occurring with the combination was smaller than that obtained by multiplication of the survival fractions occurring with either drug alone, the combined effect was considered to be synergism. Four out of five xenografts (three gastric cancer, one colon cancer) showed synergistic effects for the combination of MMC with alpha-interferon. Although two gastric cancer xenografts showed synergism for the combination of MMC with gamma-interferon, antagonistic effects were observed in one gastric cancer and one colon cancer xenograft.
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PMID:[Assessment of the combined effects of mitomycin C with alpha-interferon or gamma-interferon by the clonogenic assay technique]. 392 7

Cutaneous melanomas of Tyr-SV40E transgenic mice (mice whose transgene consists of the tyrosinase promoter fused to the coding regions of simian virus 40 early genes) strikingly resemble human melanomas in their development and progression. Unlike human melanomas, the mouse tumors all arise in genetically identical individuals, thereby better enabling expression of specific genes to be characterized in relation to advancing malignancy. The products of pigment genes are of particular interest because peptides derived from these proteins have been reported to function as autoantigens with immunotherapeutic potential in some melanoma patients. However, the diminished pigmentation characteristic of many advanced melanomas raises the possibility that some of the relevant products may no longer be expressed in the most malignant cells. We have therefore investigated the contributions of several pigment genes in melanotic vs. relatively amelanotic components of primary and metastatic mouse melanomas. The analyses reveal marked differences within and among tumors in levels of mRNAs and proteins encoded by the wild-type alleles at the albino, brown, slaty, and silver loci. Tyrosinase (the protein encoded by the albino locus) was most often either absent or undetectable as melanization declined. The protein encoded by the slaty locus (tyrosinase-related protein 2) was the only one of those tested that was clearly present in all the tumor samples. These results suggest that sole reliance on targeting tyrosinase-based antigens might selectively favor survival of more malignant cells, whereas targeting the ensemble of the antigens tested might contribute toward a more inclusive and effective antimelanoma strategy.
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PMID:Changes in expression of putative antigens encoded by pigment genes in mouse melanomas at different stages of malignant progression. 747 44

Tyrosinase (EC 1.14.18.1), the key enzyme in melanin synthesis, has been shown to be one of the targets for cytotoxic T-cell recognition in melanoma patients. To develop serological reagents useful for immunophenotyping melanoma for tyrosinase, human tyrosinase cDNA was expressed in an Escherichia coli expression vector. The purified recombinant tyrosinase was used to generate mouse monoclonal and rabbit polyclonal antibodies. The prototype monoclonal antibody, T311, recognized a cluster of protein moieties ranging from 70 to 80 kDa in tyrosinase mRNA-positive melanoma cell lines and melanoma specimens as well as in L cells transfected with tyrosinase cDNA. Untransfected L cells and L cells transfected with tyrosinase-related protein 1, TRP-1(gp75), were nonreactive. Immunohistochemical analysis of melanomas with T311 showed tyrosinase in melanotic and amelanotic variants, and tyrosinase expression correlated with the presence of tyrosinase mRNA. Melanocytes in skin stained with T311, whereas other normal tissues tested were negative. The expression pattern of three melanosome-associated proteins--tyrosinase, TRP-1(gp75), and gp100--in melanoma was also compared. Tyrosinase and gp100 are expressed in a higher percentage of melanomas than TRP-1(gp75), and the expression of these three antigens was discordant. Tyrosinase expression within individual tumor specimen is usually homogenous, distinctly different from the commonly observed heterogeneous pattern of gp100 expression.
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PMID:Immunophenotyping of melanomas for tyrosinase: implications for vaccine development. 766 56

Human melanoma antigens and their epitopes recognized by T cells have been identified using a variety of methods. These antigens are classified as 1) melanocyte specific melanosomal proteins (MART-1, gp100, tyrosinase and TRP-1), 2) proteins expressed in testis and a variety of cancers (MAGE-1, MAGE-3, BAGE and GAGE), 3) tumor specific mutated proteins (beta-catenin, MUM-1 and CDK4), and 4) others (p15). Some of the HLA-A2 binding non-mutated melanoma epitopes contained non-dominant anchor amino acids and have relatively low HLA-A2 binding affinity, suggesting that these epitopes were likely to be subdominant or cryptic self determinants. The significant correlation observed between vitiligo development and IL2 based immunotherapy suggested that autoreactive T cells specific for these self peptides were involved in melanoma regression in vivo. In addition, since adoptive transfer into patients of CTL recognizing these epitopes resulted in tumor regression, these epitopes may be tumor rejection antigens. Melanoma reactive CTL were efficiently induced from PBL of patients by in vitro stimulation with PBMC pulsed with these melanoma epitopes and may be useful in adoptive transfer protocols for the treatment of patients with metastatic melanoma. An immunization trial using the MART-1 and gp100 peptides in conjunction with incomplete Freund's adjuvant is in progress. These identified antigens may be useful for the development of new immunotherapies for the treatment of melanoma patients as well as for understanding the mechanisms of anti-tumor immune responses and autoimmune disorders against melanocytes.
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PMID:Human melanoma antigens recognized by T lymphocytes. 868 99

Melanogenesis is regulated by a variety of environmental and hormonal factors. In this study, we showed that protein kinase C (PKC) plays a major role in regulating melanogenesis in B16 mouse melanoma cells. Chronic treatment of B16 cells with phorbol dibutyrate resulted in a concentration-dependent loss of density-dependent induction of tyrosinase activity, which correlated positively with a concentration-dependent loss of PKC enzyme activity. In contrast, B16 clones overexpressing PKC alpha had increased tyrosinase activity. Different phorbol derivatives inhibited tyrosinase activity and depleted cellular PKC alpha in a manner that reflected their reported tumor-promoting activity. Western blotting analysis showed that phorbol dibutyrate decreased the amount of the brown locus gene product (TRP-1) by 50% and lowered the amount of the albino locus gene product (tyrosinase) to undetectable levels. None of the phorbol derivatives affected the level of the slaty locus protein (TRP-2). The decrease in tyrosinase and TRP-1 protein levels was found to be due to a decrease in the mRNA encoded by these genes. In addition to inhibiting the density-dependent increase in tyrosinase activity, phorbol dibutyrate inhibited some, but not all, of the 8-bromocyclic AMP-induced increase in tyrosinase activity. This was accompanied by a decrease in the amount of tyrosinase protein induced by 8-bromocyclic AMP. Although 8-bromocyclic AMP did not change the level of TRP-1, it did reverse the decrease in the amount of this protein induced by phorbol dibutyrate. The amount of TRP-2 was not altered by any of these agents. These data suggest that PKC regulates melanogenesis primarily by controlling the constitutive expression of tyrosinase and, to a lesser extent, TRP-1.
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PMID:Regulation of melanogenesis in B16 mouse melanoma cells by protein kinase C. 881 9

The infusion of TIL586 along with interleukin-2 into the autologous patient with metastatic melanoma resulted in the objective regression of tumor. A gene encoding a tumor antigen recognized by TIL586 was previously isolated and shown to encode gp75 or TRP-1. Here we report that TRP-2 was identified as a second tumor antigen recognized by a HLA-A31-restricted CTL clone derived from the TIL586 cell line. The peptide LLPGGRPYR epitope was subsequently identified from the coding region of TRP-2 based on studies of the recognition of truncated TRP-2 cDNAs and the HLA-A31 binding motif. This epitope peptide was capable of sensitizing target cells for lysis by a CTL clone at 1 nM peptide concentration. Although some modified peptides could be recognized by the CTL clone, none were found to be better recognized by T cells than the parental peptide. Like other melamona differentiation antigens, TRP-2 was only expressed in melanoma, melanocytes, and retina, but not in other human tissues tested.
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PMID:Identification of TRP-2 as a human tumor antigen recognized by cytotoxic T lymphocytes. 897 76

Recently, major advances have been made in the identification of antigens from human melanoma which are recognized by T cells. In spite of this, little is known about the optimal ways to use these antigens to treat patients with cancer. Progress in this area is likely to require accurate preclinical animal models, but the availability of such models has lagged behind developments in human tumor immunology. Whereas many of the identified human melanoma antigens are normal tissue differentiation proteins, analogous murine tumor antigens have not yet been identified. In this paper we identify a normal tissue differentiation antigen, tyrosinase-related protein 2 (TRP-2), expressed by the murine B16 melanoma which was found by screening a cDNA library from B16 with tumor-reactive cytotoxic T lymphocytes (CTL). A peptide conforming to the predicted MHC class I H2-Kb binding motif, TRP-2181-188, was identified as the major reactive epitope within TRP-2 recognized by these anti-B16 CTLs. By site-directed mutagenesis, it was shown that alteration of this epitope eliminated recognition of TRP-2. It was further demonstrated that a CTL line raised from splenocytes by repeated stimulation in vitro with this peptide could recognize B16 tumor and was therapeutic against 3-d-old established pulmonary metastases. The use of TRP-2 in a preclinical model of tumor immunotherapy may be helpful in suggesting optimal vaccination strategies for cancer therapy in patients.
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PMID:Identification of tyrosinase-related protein 2 as a tumor rejection antigen for the B16 melanoma. 905 45

Both melanocytes and glial cells are derived embryologically from the neural ectoderm. Their malignant transformed counterparts, melanoma and glioma cells, respectively, may share common antigens. Numerous tumor-associated antigens have been identified in melanomas but only a few a gliomas. Using an established reverse transcriptase polymerase chain reaction plus Southern blot assay, we compared the mRNA expression of melanoma-associated antigens (MAAs) of melanomas to brain tumors primarily derived from glial cells. The MAAs studied included tyrosinase (Tyr), tyrosinase-related protein-1 and -2 (TRP-1 and TRP-2), gp100, human melanoma antigen-encoding genes 1 and 3 (MAGE-1 and MAGE-3), and melanotransferrin (p97). Glioblastoma multiforme (n = 21), anaplastic astrocytoma (n = 3), ependymoma (n = 2), meningioma (n = 3), oligodendroglioma (n = 1), and melanoma (n = 12) tumor specimens were assayed for MAA mRNA expression. Glioblastoma multiforme, astrocytoma, and melanoma cell lines were also assayed. We observed that individual MAA mRNAs were expressed in these brain tumors and cell lines at varying frequencies. The melanogenesis-pathway-related MAAs Tyr, TRP-1, TRP-2, and gp100 mRNAs were also expressed at different levels in normal brain tissues but at a much lower frequency than in glioblastoma multiforme and melanoma. MAGE-1 and MAGE-3 mRNA were expressed in different types of tumor specimens and cell lines but never in normal brain tissue. Tumor antigen p97 was expressed in all types of tumors and also in normal brain tissues. These studies demonstrate that melanomas and primary brain tumors express common MAAs and could be exploited in patients with malignant glioma by active specific immunotherapy against these common MAAs.
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PMID:Molecular detection of tumor-associated antigens shared by human cutaneous melanomas and gliomas. 917 5


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