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)

The highly metastatic human melanoma cell line BLM was transfected with the E1A or E1A + E1B regions of adenovirus 5 (Ad5). A series of progression markers, correlated with the malignant phenotype of parental BLM (including calcyclin, thymosin beta 10, plasminogen activator inhibitors types 1 and 2, urokinase type and tissue type plasminogen activators, vimentin, tissue type transglutaminase, and interleukin-6), was collectively repressed in the transfectants, whereas several control genes were not affected or even induced. The apparently coordinate repression of a set of markers by the same regulator gene, Ad5 E1A in this case, suggests the existence of one pathway under the control of a main switch and predicts that one or more as yet unidentified cellular master genes normally exert this function. A reduced oncogenicity was observed after subcutaneous inoculation of the E1A transfectants into nude mice and provides additional evidence in support of a tumor suppressor function of Ad5 E1A.
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PMID:Simultaneous suppression of progression marker genes in the highly malignant human melanoma cell line BLM after transfection with the adenovirus-5 E1A gene. 878 Jun 94

Recent evidence indicates that CD44, a multifunctional adhesion receptor involved in cell-cell as well as in cell-matrix interactions, plays an important role in local progression and metastasis of malignant tumors. We have studied a set of human melanoma cell lines differing in their metastatic potential in nude mice as well as in normal melanocytes for changes in CD44 expression and function. All melanocytes and melanoma cell lines tested highly expressed the CD44 standard form (CD44s, 85 kDa) but variants at low levels only. With respect to one of the CD44-associated functions primarily involved in tumor progression we found that two highly metastatic tumor cell lines, MV3 and BLM, showed fivefold higher migration rates towards hyaluronate than melanomas with low metastatic potential and normal melanocytes. Moreover, the highly metastatic cell lines expressed four- to sixfold higher levels of the CD44 epitope involved in hyaluronic acid-binding (monoclonal antibody Hermes-1) than less aggressive melanomas and melanocytes. Hermes-1 efficiently blocked haptotaxis to hyaluronate, supporting the functional relevance of this epitope. In contrast, expression levels of other CD44s epitopes recognized by seven different anti-CD44 monoclonal antibodies were unchanged, suggesting that the migratory behaviour of the cells depends on the formation of the hyaluronate-binding Hermes-1 epitope rather than on the overall CD44s surface expression, which was virtually identical in all melanoma and melanocyte cell lines tested. Differences in the accessibility of the hyaluronate-binding epitope defined by Hermes-1 correlated with the phosphorylation state of CD44s, probably reflecting different activation states of the receptor. Furthermore, immunoprecipitation and pulse/chase studies revealed a three- to fivefold increase in CD44 synthesis in the highly aggressive melanoma cells as compared to the other cell lines and the melanocytes, indicating a reduction of CD44 half-life and up-regulation of turnover. Moreover, highly aggressive melanoma cell lines were found to shed significant amounts of CD44 from the cell surface and to secrete its ligand hyaluronic acid, which may refer to an "autocrine' mechanism mediating melanoma cell motility.
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PMID:Migration of highly aggressive melanoma cells on hyaluronic acid is associated with functional changes, increased turnover and shedding of CD44 receptors. 883 18

Collagen IV, laminin and fibronectin are constituents of the cerebral extracellular matrix (ECM), which is critical in glioma cell invasion. The aim of the present study was to evaluate the integrin dependent cell-matrix interactions of two tumors with different invasive properties under matrixfree conditions. Two human glioma (GaMG, U373) and melanoma (MV3, BLM) cell lines were grown in serum free medium. Immunofluorescence microscopy of collagen IV, laminin, and fibronectin was performed. The adhesion of monolayer cells and their migration out of multicellular spheroids was quantified for these ECM components. Integrin chains known to act as laminin receptors were blocked by specific antibodies in additional migration assays. All cell lines expressed all the ECM components under serum free conditions. Tumor cell adhesion and migration in both glioma and melanoma cell lines was increased by all the ECM components, laminin being the strongest promotor of migration. However, migration was dose dependent in gliomas, whereas melanomas revealed a dose optimum of 10 micrograms/ml laminin. Antibodies against alpha 3 integrins significantly reduced migration on laminin in all cell lines, anti-beta 1 in all cell lines except U373. Anti-alpha 2 in BLM showed a strong effect, anti-alpha 6 was a stronger inhibitor in glioma than in melanoma cells. Integrins are functionally involved in tumor cell locomotion on laminin. The blocking of laminin related integrin chains markedly reduces cell motility in a varying manner between the cell lines. Moreover, different cell lines utilize different integrins as the laminin receptor.
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PMID:ECM dependent and integrin mediated tumor cell migration of human glioma and melanoma cell lines under serum-free conditions. 904 41

We studied the relation between tumour vascular density and tumour growth rate, metastatic incidence and vascular permeability factor (VPF) mRNA levels in a human xenograft model described previously. Vascular density was determined by automated image analysis. Xenografts derived from cell lines BLM and MV3 showed the highest mean vascular density (MVD), the highest in vivo growth rate, high VPF mRNA levels and rapid development of lung metastases. Xenografts of cell lines M14, Mel57 and MV1 showed a significantly lower degree of vascularization, lower in vivo growth rates and lower levels of VPF mRNA, but formed lung metastases with a similar incidence as those of BLM and MV3. Xenografts from cell line 1F6 did not form lung metastases, whereas tumours derived from a spontaneous mutant of 1F6, designated 1F6m, gave rise to lung metastases to the same extent as Mel57, M14 and MV1 tumours. MVD values in 1F6 and 1F6m xenografts, VPF mRNA levels and in vivo growth rates of 1F6 and 1 F6m xenografts, however, were similar. In conclusion, in the melanoma xenograft model vascular density is correlated with in vivo growth rate and with in vitro VPF mRNA levels, but not with the ability to metastasize.
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PMID:Vascular density in melanoma xenografts correlates with vascular permeability factor expression but not with metastatic potential. 930 53

The adoptive transfer of tumor-specific cytotoxic T cells (CTL) offers a promising perspective in cancer immunotherapy. However, the ex vivo-generated T lymphocytes are mostly IL-2-dependent. Here we explored the possibility of circumventing the requirement for IL-2, known for severe side effects in the patient, and of simultaneously targeting the CTL towards the tumor by the use of 2 bi-specific antibody fragments. As a model system, we used SCID mice bearing an s.c.-implanted human melanoma line (BLM-gp100) and in vitro-generated CTL specific for the gp100-derived immunogenic peptide YLEPGPVTA, which were injected i.v. with delay. To maintain the cytotoxic potential of the transferred CTL, 2 bi-specific antibody (biAb) fragments were generated which bound with one arm either CD3 or CD28, a combination known to support the activation of CTL. For targeting the CTL, both biAbs contained the F(ab') part of HD-Me13, an antibody recognizing p97, a non-immunogenic melanoma-associated surface molecule. In vitro and in vivo, the addition of the 2 biAbs increased the cytotoxic potential of the gp100-specific CTL and supported their clonal expansion in the absence of IL-2. Correspondingly, significantly higher numbers of CTL were recovered from melanoma-bearing SCID-mice that received the 2 biAb than from mice treated with the CTL only. In animals treated with CTL plus both biAbs, the primary tumor did not grow, and none of the mice developed metastases. Thus, this set of bi-specific antibody fragments was proved to target effector cells in the tumor-bearing host and to efficiently support in vivo clonal expansion and cytolytic activity of in vitro-generated CTL.
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PMID:Human melanoma therapy in the SCID mouse: in vivo targeting and reactivation of melanoma-specific cytotoxic T cells by bi-specific antibody fragments. 1020 66

Besides its proinflammatory properties, interleukin-8 (IL-8) has been suggested as an important promoter for melanoma growth. To study the role of IL-8 in melanoma biology, we determined the in vivo expression of IL-8 mRNA by in situ hybridization in primary melanoma lesions and metastases. High levels of melanoma cell-associated IL-8-specific transcripts were exclusively detected in close vicinity of necrotic/hypoxic areas of melanoma metastases, whereas both in primary melanomas and in non-necrotic metastases IL-8 expression was low or absent. To analyze further the up-regulation of IL-8 mRNA expression in necrotic/hypoxic tumor areas, human melanoma cell lines of different aggressiveness exposed to severe hypoxic stress (anoxia) were used as an in vitro model. Anoxia induced IL-8 mRNA and protein expression in the highly aggressive/metastatic cell lines MV3 and BLM but not in the low aggressive cell lines IF6 and 530. As shown by IL-8 promoter-dependent reporter gene analysis and mRNA stability assays, elevated mRNA levels in melanoma cells were due to both enhanced transcriptional activation and enhanced IL-8 mRNA stability. Interestingly, transcriptional activation was abolished by mutations in the AP-1 and the NF-kappaB-like binding motifs, indicating that both sites are critical for IL-8 induction. Concomitantly, anoxia induced an enhanced binding activity of AP-1 and NF-kappaB transcription factors only in the highly aggressive cells. From our in vitro and in vivo data we suggest that anoxia-induced regulation of IL-8 might be a characteristic feature of aggressive tumor cells, thus indicating that IL-8 might play a critical role for tumor progression in human malignant melanoma.
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PMID:Anoxia-induced up-regulation of interleukin-8 in human malignant melanoma. A potential mechanism for high tumor aggressiveness. 1048 33

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are involved in tumour progression and metastasis. In this study, we investigated the in vitro and in vivo expression patterns of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1 and TIMP-2 mRNA and protein in a previously described human melanoma xenograft model. This model consists of eight human melanoma cell lines with different metastatic behaviour after subcutaneous (s.c.) injection into nude mice. MMP-1 mRNA was detectable in all cell lines by reverse transcription polymerase chain reaction (RT-PCR), but the expression was too low to be detected by Northern blot analysis. No MMP-1 protein could be found using Western blotting. MMP-2 mRNA and protein were present in all cell lines, with the highest expression of both latent and active MMP-2 in the highest metastatic cell lines MV3 and BLM. MMP-3 mRNA was expressed in MV3 and BLM, and in the non-metastatic cell line 530, whereas MMP-3 protein was detectable only in MV3 and BLM. None of the melanoma cell lines expressed MMP-9. TIMP-1 and TIMP-2 mRNA and protein, finally, were present in all cell lines. A correlation between TIMP expression level and metastatic capacity of cell lines, however, was lacking. MMP and TIMP mRNA and protein expression levels were also studied in s.c. xenograft lesions derived from a selection of these cell lines. RT-PCR analysis revealed that MMP-1 mRNA was present in MV3 and BLM xenografts, and to a lesser extent in 530. Positive staining for MMP-1 protein was found in xenograft lesions derived from both low and high metastatic cell lines, indicating an in vivo up-regulation of MMP-1. MMP-2 mRNA was detectable only in xenografts derived from the highly metastatic cell lines 1F6m, MV3 and BLM. In agreement with the in vitro results, the highest levels of both latent and activated MMP-2 protein were observed in MV3 and BLM xenografts. With the exception of MMP-9 mRNA expression in 530 xenografts, MMP-3, MMP-9, and TIMP-1 mRNA and protein were not detectable in any xenograft, indicating a down-regulated expression of MMP-3 and TIMP-1 in vivo. TIMP-2 mRNA and protein were present in all xenografts; interestingly, the strongest immunoreactivity of tumour cells was found at the border of necrotic areas. Our study demonstrates that of all tested components of the matrix metalloproteinase system, only expression of activated MMP-2 correlates with increased malignancy in our melanoma xenograft model, corroborating an important role of MMP-2 in human melanoma invasion and metastasis.
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PMID:Matrix metalloproteinases in human melanoma cell lines and xenografts: increased expression of activated matrix metalloproteinase-2 (MMP-2) correlates with melanoma progression. 1055 45

Local tumor invasion into the surrounding brain tissue is a major characteristic of malignant gliomas. These processes critically depend on the interaction of tumor cells with various extracellular matrix (ECM) components. Because only little quantitative information about expression of ECM gene products in general and expression in response to alterations of the surrounding environment is available, the present study was designed. Four human glioblastoma cell lines (U373MG, U138MG, U251MG, GaMG) as well as four human melanoma cell lines (MV3, BLM, 530, IF6) were tested with semiquantitative RT-PCR for their ability to express mRNA of different human ECM components (fibronectin, decorin, tenascin, collagen I, collagen IV, versican). In addition, two human medulloblastoma (MHH-Med 1, MHH-Med 4) and two fibrosarcoma (HT1080, U2OS) cell lines were analyzed. Cells which were grown in DMEM medium containing 10% FCS expressed most of the analyzed protein components. When the same medium, but depleted of ECM proteins by filtrating through a membrane with cut-off at > 100 kD was used, basal mRNA expression of the ECM proteins was changed in most of the examined cell lines. Using serum free conditions, most of the cell lines again showed a variation in the expression pattern of mRNA encoding for the different ECM proteins compared to the other medium conditions. Comparing different cell lines from one tumor entity or different tumor groups, ECM expression was heterogeneous with regard to the different tumor entities as well as within the entities themselves. Migration assays revealed heterogeneous responses between the different cell lines, ECM components and culture conditions, making it difficult to correlate ECM expression patterns and migratory behavior. Our results revealed that all examined cell lines are able to produce ECM proteins in vitro. This suggests that tumor cells can modulate their microenvironment in vitro which has to be taken into consideration for studies related to migration and invasion.
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PMID:Expression of different extracellular matrix components in human brain tumor and melanoma cells in respect to variant culture conditions. 1058 65

Tumor angiogenesis, a major requirement for tumor outgrowth and metastasis formation, is regulated by pro- and anti-angiogenic factors. We have studied the expression of a panel of angiogenic factors, and of the angiogenesis inhibitor angiostatin, in a panel of human melanoma cell lines giving rise to xenografts with different vascular densities. Angiogenic-factor expression was analyzed in vitro (cell lines) and in vivo (xenografts), both at mRNA (RT-PCR and Northern blot) and at protein level (ELISA and Western blot). In vitro angiostatin generation was assessed by Western-blot analysis. Expression of bFGF and VEGF was clearly correlated with a high degree of vascularization, confirming the importance of these factors for tumor angiogenesis. In addition, there was exclusive or elevated in vitro expression of angiogenic factors IL-8, PDGF-AB, and, to a lesser extent, midkine in cell lines that formed highly vascularized tumors. A similar angiogenic-factor-expression pattern was found in the corresponding xenografts, with the exception of VEGF. In most cell lines, this factor had low expression in vitro which was strongly enhanced in vivo. Although all 8 melanoma cell lines were able to excise the angiostatin fragment from the plasminogen parent molecule in vitro, cell lines BLM and M14 showed the most potent angiostatin generation. In vitro angiostatin generation by cell lysates prepared from melanoma xenografts was comparable in all xenograft types. Thus, in our model system we found no correlation between angiostatin generation and vascular density. Our study has limited the number of pro-angiogenic factors that may be involved in melanoma angiogenesis, and provides evidence for the notion that regulation of tumor angiogenesis is dependent on multiple factors. Inhibition of angiogenesis for therapeutic purposes, therefore, should preferably not concentrate on a single factor.
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PMID:Angiogenic balance in human melanoma: expression of VEGF, bFGF, IL-8, PDGF and angiostatin in relation to vascular density of xenografts in vivo. 1084 89

Activation of matrix metalloproteinase-2 (MMP-2) is mediated by binding to the complex of membrane-type matrix metalloproteinase-1 (MT1-MMP) with tissue inhibitor of MMP-2 (TIMP-2) on the cell surface. Binding of MMP-2 to integrin alpha(v)beta(3) has been implicated in presenting activated MMP-2 on the cell surface of invasive cells, but interactions with the MT1-MMP-TIMP-2 system have not been considered. Therefore, we studied the expression and interaction of MT1-MMP, MMP-2 and TIMP-2 in the alpha(v)beta(3)-negative melanoma cell line BLM and in its beta(3)-transfected, alpha(v)beta(3)-expressing counterpart BLM-beta(3), both on cell lines and in xenografts. Total expression levels of MMP-2, MT1-MMP and TIMP-2 did not differ markedly between the alpha(v)beta(3)-negative and alpha(v)beta(3)-positive cells. Remarkable differences, however, exist in the presence of active MMP-2 and MT1-MMP. Zymography on cell lysates revealed that active MMP-2 was restricted to alpha(v)beta(3)-positive cell line and clearly accumulated in xenografts derived from the BLM-beta(3) cells, confirming the relevance of this integrin for MMP-2 function. Western blotting of cell lysates showed that processing of proMT1-MMP to the activated form was enhanced in BLM-beta(3). The ratio of active and inactive MT1-MMP was 3-fold higher in the beta(3)-transfectants. Immunofluorescence double-labeling followed by confocal laser microscopy showed co-localization of MT1-MMP and alpha(v)beta(3) on BLM-beta(3) cells. In xenografts from BLM-beta(3) cells, active MT1-MMP was markedly increased. Our results demonstrate that expression of alpha(v)beta(3) in cell lines and xenografts was accompanied by an accumulation of active MT1-MMP and MMP-2. Furthermore, MT1-MMP and alpha(v)beta(3) are co-localized on the cell membrane of tumor cells. These findings suggest that activated MT1-MMP co-localized with alpha(v)beta(3) may be involved in activation of alpha(v)beta(3)-bound MMP-2.
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PMID:Expression of integrin alpha(v)beta(3) correlates with activation of membrane-type matrix metalloproteinase-1 (MT1-MMP) and matrix metalloproteinase-2 (MMP-2) in human melanoma cells in vitro and in vivo. 1086 47


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