Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As a preliminary to transducing human melanoma cells with lymphokine genes, we sought for constitutive gene expression and production of eight interleukins, tumour necrosis factors and granulocyte-colony stimulating factor in 19 human melanoma cell lines. Conversion of RNA into cDNA by reverse transcriptase and polymerase chain reaction (RT-PCR) were employed to evaluate gene expression while enzyme-linked immunosorbent assays (ELISA) or biological assays were used to assess the presence of proteins. No expression of interleukins (IL) 3, 4, and 5 or interferon-gamma RNA was found, while the other cytokines were variably expressed in melanoma lines, with IL-1 alpha, IL-1 beta, IL-6, IL-8, being detectable in most of the lines. At protein level, 10 melanoma cells were tested with ELISA and all were found to produce IL-8, five produced IL-6, two tumour necrosis factor (TNF)-alpha, one IL-1 alpha and two TNF beta. The levels of TNF beta were at the limit of test sensitivity. The amount of various cytokines released by the different lines varied widely. Biological assay with the D10-G4 clone confirmed the presence of IL-1 alpha in the supernatant of melanoma (ME) 10221 and revealed an IL-1 activity in the supernatant of Me 4024/1. The proliferating activity of melanoma supernatants on D10-G4 was inhibited by treatment with polyclonal antibodies against IL-1 alpha but not with antibodies against IL-1 beta. TNF biological activity was tested against the TNF-susceptible fibrosarcoma WEHI 164 clone 13.(ABSTRACT TRUNCATED AT 250 WORDS)
Melanoma Res 1992 Sep
PMID:Expression of cytokine genes, including IL-6, in human malignant melanoma cell lines. 145 Jun 72

Suramin, a polysulfonated naphthylurea, has anti-reverse transcriptase and anti-proliferative activities and inhibits the binding of various growth factors to their cell surface receptors. This drug is used in the treatment of acquired immunodeficiency syndrome and several types of cancers. Increased levels of circulating glycosaminoglycans have been observed in suramin-treated cancer patients, suggesting that it may inhibit glycosaminoglycan catabolism. Melanoma-derived heparanase, a heparan sulfate-specific endo-beta-D-glucuronidase that plays an important role in metastatic melanoma cell invasion through basement membranes, is inhibited by suramin in a dose-dependent manner: 100% inhibition was observed at a concentration of approximately 100 microM. Structurally related polysulfonated compounds, such as trypan blue and Evans blue, had lower heparanase inhibitory activities: the concentrations required for 50% heparanase inhibition (ID50) were 310-320 microM and six times higher than for suramin (ID50 = 46 microM). Oversulfated heparin tetrasaccharide, whose average molecular size is similar to suramin, had also much lower heparanase inhibitory activity than suramin. The inhibition constants (Ki) for suramin and oversulfated heparin tetrasaccharide were 48 and 290 microM, respectively. Suramin had a remarkable inhibitory activity against B16 melanoma cell invasion through reconstituted basement membranes (ID50 less than 10 microM). The inhibitory effects of suramin on melanoma heparanase and cell invasion appeared to be completely independent of its antiproliferative activity, because significant effects on melanoma cell growth were not observed at the concentrations of suramin used in this study. The results suggest that the antimetastatic effects of suramin may be due to its antiinvasive rather than antiproliferative activities.
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PMID:Suramin. A potent inhibitor of melanoma heparanase and invasion. 203 58

Melanoma cells often display a multidrug-resistant phenotype, but the mechanisms involved are largely unknown. We have studied here the recently identified transport-associated proteins, MRP and LRP, and the well-known drug resistance marker P-glycoprotein using a panel of 16 human melanoma cell lines and 71 benign and malignant melanocytic tissue samples. By flow cytometry and immunohistochemistry, expression of P-glycoprotein was not detectable on the protein level in the 10 cell lines analyzed, although by reverse transcriptase polymerase chain reaction, MDR-1 gene expression was demonstrated in 2 of 10 cell lines. In addition, immunohistology revealed P-glycoprotein expression in only 1 of 71 melanocytic lesions. In contrast, MRP was detected in a subset of melanoma cell lines by reverse transcriptase polymerase chain reaction and immunohistology (4 of 10). LRP expression was observed in 8 of 10 melanoma cell lines by immunochemistry and in 10 of 10 by reverse transcriptase polymerase chain reaction. Furthermore, MRP was detected immunohistologically in almost 50% of primary and metastatic melanoma specimens, although no significant differences were found between metastases taken before or after chemotherapy. Expression of LRP was detected in a subset of nevi with nevus cells exhibiting up to 25% positive LRP reactivity. In 13 of 21 primary melanomas and 23 of 37 metastases, more than 25% of tumor cells were stained by the LRP-56 monoclonal antibody. Particularly in the group of metastases with more than 50% of LRP-positive cells, 7 of 11 of the metastases had been previously exposed to chemotherapeutic drugs. Although the expression of membrane transport proteins may explain only the chemoresistance toward lipophilic, natural compounds and not resistance against alkylating agents, the lack of P-glycoprotein expression after chemotherapeutic treatment and the significant expression of MRP and LRP in melanoma cells provide first insights into the drug-resistant phenotype in melanoma. Additional studies analyzing the role of MRP and LRP in chemoresistance of melanoma are warranted.
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PMID:Membrane transport proteins associated with drug resistance expressed in human melanoma. 749 78

Choroidal and ciliary body melanomas disseminate exclusively by a hematogenous route because there are no lymphatics inside the eye. Although angiogenesis is an absolute precondition for metastasis in this tumor system, not all morphologic expressions of tumor angiogenesis are associated with metastasis from choroidal and ciliary body melanomas. Specifically, the remodeling of the microcirculation to form vascular networks is very strongly associated with metastasis. Type VI collagen is upregulated in tissue remodeling and the generation of tissue patterns and is either not present in the normal choroid or present at very low levels. This study was designed to investigate the possible expression of type VI collagen in the stroma of choroidal and ciliary body melanomas. Type VI collagen was detected in tissue sections from five primary choroidal melanomas and three melanomas involving the choroid and ciliary body in the subendothelial compartment of the microcirculation and in avascular areas by immunohistochemistry. Melanoma cell lines were established from each of these tumors. Cultured melanoma cells invaded into type I collagen gels and expressed type VI collagen by immunohistochemistry. Using specific primers for human type VI collagen, the expected band size (413 base pairs) was isolated from one of the cell lines by reverse transcriptase PCR. The presence of type VI collagen in the melanoma tumor stroma reflects active remodeling of the uveal extracellular matrix microenvironment by the melanoma cells themselves. Before the formation of the microvasculature, the expression of type VI collagen and of the other matrix components, such as hyaluronan, to which it binds, may erect a scaffold permitting the formation of higher order stromal patterns such as vascular networks. These stromal patterns, which are markers of tumor progression, may be detectable clinically by a specialized form of ultrasonography that detects backscatterers of the same dimension as tissue compartments encircled by vascular loops in networks.
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PMID:Expression of type VI collagen in uveal melanoma: its role in pattern formation and tumor progression. 868 40

Interleukin-8 (IL-8) is a cytokine that is thought to promote melanoma tumour progression. We evaluated and adapted a non-radioactive, reverse transcriptase-polymerase chain reaction method for semiquantitative analysis of IL-8 mRNA expression. Using this technique we studied the regulation of IL-8 levels in the melanoma cell line Colo 38. Seeding of melanoma cells into culture dishes resulted in a significant increase of IL-8 expression, which could be attributed to adherence. A pronounced increase of IL-8 mRNA expression and protein production was induced by tumour necrosis factor-alpha (TNF alpha). Interferon-gamma (IFN gamma) partially inhibited TNF alpha-induced IL-8 secretion, whereas no influence on IL-8 mRNA levels was detected. The inhibitory affect of IFN gamma on melanoma cells is in contrast to its stimulatory effect on melanocytes.
Melanoma Res 1996 Aug
PMID:Regulation of interleukin-8 mRNA expression and protein secretion in a melanoma cell line by tumour necrosis factor-alpha and interferon-gamma. 887 50

Spitz naevi and halo naevi are benign melanocytic lesions that share many histological features with malignant melanoma. All lesions are characterized by a brisk infiltration of lymphocytes, mainly of the T cell subtype, and halo naevi are known to undergo spontaneous regression. Since the benign nature of Spitz naevi and halo naevi might therefore be caused by specific T cell responses against tumour-associated antigens, it was found of interest to characterize this T cell response in detail. A reverse transcriptase-polymerase chain reaction (RT-PCR)-based method adapted for analysis of paraffin-embedded material combined with Southern blot analysis has been used to analyse the T cell receptor (TCR) AV and BV repertoires of infiltrating lymphocytes in 14 different melanocytic lesions. The results have shown that only a few particular TCRAV and TCRBV regions are expressed in each lesion. To evaluate the T cell response, it is of interest to know the HLA-type of the analysed lesions, since most melanoma-specific effector lymphocytes are CD8+ cytotoxic T cells and therefore HLA class I-restricted. As blood samples were not available from any of these patients, an RT-PCR method using HLA-A2-specific primers was used to analyse for the presence of this allele. The preferentially expressed TCRAV genes were sequenced, and this analysis showed that the high expression of these TCRAV genes was due to a clonal or oligocional expansion of T cells. In summary, the expression of relatively few TCR variable regions indicates a clonal expansion of T cells.
Melanoma Res 1997 Feb
PMID:Analysis of T cell receptor AV and BV chain gene expression by infiltrating lymphocytes in Spitz naevi and in halo naevi. 906 65

Human malignant melanoma is characterised by unresponsiveness to conventional chemotherapy. Melanoma-derived cell lines are often markedly chemoresistant, suggesting that cellular mechanisms mediate the multidrug resistance (MDR) phenotype. The multidrug resistance-associated protein (MRP) is a drug transporter protein associated with resistance to a broad spectrum of lipophilic drugs. To investigate whether MRP is involved in intrinsic drug resistance of human melanoma, we analysed expression and functional activity of MRP as well as its impact on chemoresistance in 40 melanoma cell lines (35 established by us from primary and metastatic lesions and 5 obtained from international sources), as well as in one dysplastic naevus-derived cell line and in normal melanocytes. By reverse transcriptase-polymerase chain reaction various levels of MRP mRNA were detected in all melanoma cell lines, and by immunoblot the corresponding protein in a high percentage of them. Functional activity of MRP was assayed by analysing cellular accumulation of 3H-daunomycin (3H-DM) and calcein in response to MRP-modulators by beta-spectrometric and fluorescence-activated cell sorter analysis, respectively. Probenecid (PRO), N-ethylmaleimide (NEM) and benzbromarone (BB) moderately (< or = 1.43-fold) but significantly enhanced intracellular accumulation of MRP substrate probes corresponding to MRP expression. Moreover, the sensitivity of melanoma cell lines to daunomycin (DM) and doxorubicin (DOX), but not to vinblastine (VBL), etoposide (VP-16) and cisplatin (CDDP), analysed by an MTT-based survival assay, were inversely correlated with MRP-gene expression. Our results imply that MRP may be a component of the intrinsic chemoresistance phenotype characteristic of human malignant melanoma.
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PMID:Possible role of the multidrug resistance-associated protein (MRP) in chemoresistance of human melanoma cells. 909 73

D1 dopamine receptor mRNA has been demonstrated in mouse melanoma cells, and the expression of these G-protein-coupled receptors in human melanoma was therefore presumed when dopamine receptor binding radiopharmaceuticals were found to be useful for the detection of metastases in whole-body scintigraphy. The aim of this study was thus to investigate if D1 dopamine receptor mRNA or protein could be directly demonstrated in melanoma cells. The presence of D1 dopamine receptor mRNA was investigated in six human melanoma cell lines from metastases using reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, in vitro binding assays with the D1 dopamine receptor agonist 125I-Sch 23982 were performed in 19 melanoma metastases. No D1 dopamine receptor mRNA could be detected by RT-PCR. All melanotic metastases were found to accumulate 125I-Sch 23982, with the presence of binding sites and intensity of 125I-Sch 23982 labelling correlating to the amount of melanin present in the metastases. Two amelanotic melanomas did not accumulate 125I-Sch 23982. D1 dopamine receptors could not be detected by means of RT-PCR or in vitro binding assays in human melanomas. Detection of antagonists is best explained by non-specific binding to melanin.
Melanoma Res 1997 Apr
PMID:D1 dopamine receptors are not expressed in human melanoma. 916 77

Melanoma tumor antigens, MAGE-1 and -3 are presented on HLA-A1 and -Cw*1601, or -A1 and -A2, respectively, to the corresponding cytotoxic T lymphocytes (CTL). If CTL recognizing these antigens were generated in patients, clones of positive tumor cells should be eliminated. To ascertain whether such an immunological response is active in patients with lung cancer and to determine what fraction of lung cancer patients are candidates for MAGE oriented immunotherapy, we assessed the relationship between HLA-A1 or -A2 expression and MAGE-1 or -3 gene expression in their tumors. MAGE-1 and -3 were detected in 18/55 (33%) and 23/55 (42%), respectively, by reverse transcriptase (RT)-polymerase chain reaction (PCR). Allele specific PCR revealed HLA-A1 and -A2 alleles to be expressed in 0/55 (0%) and 22/55 (40%) of our cohort, respectively. Among the 22 patients with HLA-A2 genotype, expression of HLA class I antigens detectable by immunohistochemistry was lost in five (23%) cases. The frequency of MAGE-3 expression in HLA-A2 patients was 5/17 (29%), somewhat lower than that of patients without HLA-A2 expression, 18/38 (47%), although the difference was not statistically significant (P = 0.17). Neither was there a significant association between HLA-A2/MAGE-3 co-expression and survival (P = 0.15, logrank test). We conclude that there is no clear evidence for elimination of lung cancers co-expressing HLA-A2 and MAGE-3 in vivo. Approximately 10% (5/55) of Japanese lung cancer patients are potential candidates for MAGE-3-based immunotherapy.
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PMID:Frequency of MAGE-3 gene expression in HLA-A2 positive patients with non-small cell lung cancer. 971 30

Recently p73, a novel p53 homologous tumour suppressor gene, has been cloned and mapped to chromosome 1p36. Like p53, important functions of p73 in controlling the cell cycle and programmed cell death have been described. Loss of p73 has been demonstrated in neuroblastomas and its involvement in tumorigenesis has been suggested to occur in other neuroectodermal cancers. Since genetic alterations at the tumour suppressor locus 1p36 have been also identified in malignant melanomas, we investigated the expression of p73 in a panel of nine different human melanoma cell lines, 17 melanocytic naevi, 17 primary malignant melanomas and 20 metastases by reverse transcriptase polymerase chain reaction (PCR) and Southern blotting. We observed significant p73 mRNA expression in all the cell lines and tissue specimens except one benign melanocytic naevus and one melanoma metastasis. Sequencing the PCR fragments of nine melanoma cell lines derived from primary tumours and five metastases over the entire p73 DNA binding domain revealed wild-type sequences in all cases. In summary, we conclude that loss of p73 mRNA expression or mutations in the p73 DNA binding domain do not represent common genetic events involved in the pathogenesis of malignant melanomas.
Melanoma Res 1998 Dec
PMID:Loss of expression or mutations in the p73 tumour suppressor gene are not involved in the pathogenesis of malignant melanomas. 991 12


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