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: UMLS:C0025202 (melanoma)
69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed an improved mouse dorsal air sac model for quantifying in vivo tumor-induced angiogenesis. In our improved model, tumor angiogenesis is determined by measuring the blood volume in an area of skin held in contact with a tumor cell-containing chamber, using 51Cr-labeled red blood cells (RBC). The blood volume induced by murine B16-BL6 melanoma cells increased linearly with the cell number in the range from 2 x 10(5) to 5 x 10(6). Ten of 11 human tumor cell lines examined induced a significant increment in blood volume. For three representative human tumor cell lines (A549, WiDr. and HT1080 cells) that showed different angiogenic potencies, the levels of vascular endothelial growth factor (VEGF) produced by the tumor cells cultured under conditions of hypoxia and high cell density were correlated with the degree of in vivo angiogenesis. Using the improved model, it was confirmed that TNP-470, a well-known inhibitor, and borrelidin, an antibiotic from Streptomyces rochei, significantly inhibited the WiDr cell-induced angiogenesis. Borrelidin also inhibited spontaneous lung metastasis of B16-BL6 melanoma at the same dose that inhibited angiogenesis. Our results suggest that the improved mouse dorsal air sac model can be used for simple and quantitative measurement of tumor-induced angiogenesis and its inhibition.
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PMID:Establishment of a quantitative mouse dorsal air sac model and its application to evaluate a new angiogenesis inhibitor. 1075 46

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

Expression of heparan sulfate-degrading endoglycosidases, commonly referred to as heparanases, correlates with the metastatic potential of tumor cell lines, and treatment with heparanase inhibitors markedly reduces the incidence of metastasis in experimental animals. We purified a 50 kDa heparanase from human hepatoma and placenta and cloned a cDNA and gene encoding a protein of 543 amino acids. Only one heparanase sequence was identified, suggesting that this enzyme is the dominant endoglucuronidase in mammalian tissues. Expression of the cloned cDNA in insect and mammalian cells yielded 65 kDa and 50 kDa recombinant proteins. The 50 kDa enzyme represents an N-terminal processed enzyme that is at least 200-fold more active than the full-length 65 kDa form. Processing was demonstrated following incubation of the full-length recombinant enzyme with intact tumor cells. The heparanase mRNA and protein are preferentially expressed in metastatic cell lines and in specimens of human melanomas and carcinomas. In the colon, both the heparanase mRNA and protein are expressed already at the stage of tubulovillous adenoma, but not in the adjacent 'normal-looking' colon epithelium. Non-metastatic murine T lymphoma and melanoma cells transfected with the heparanase gene acquired a highly metastatic phenotype in vivo. Apart from its involvement in the egress of cells from the vasculature, heparanase is tightly involved in angiogenesis, both directly--by promoting invasion of endothelial cells (vascular sprouting), and indirectly--by releasing heparan sulfate-bound basic fibroblast growth factor, and generating HS degradation fragments that promote bFGF activity. The angiogenic potential of heparanase was demonstrated in vivo (Matrigel plug assay) by showing a three to fourfold increase in neovascularization induced by Eb T lymphoma cells following their transfection with the heparanase gene. The ability of heparanase to promote both tumor angiogenesis and metastasis makes it a promising target for cancer therapy.
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PMID:Mammalian heparanase as mediator of tumor metastasis and angiogenesis. 1090 16

Vascular endothelial growth factor, fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) and their cognate receptor tyrosine kinases are strongly implicated in angiogenesis associated with solid tumors. Using rational drug design coupled with traditional screening technologies, we have discovered SU6668, a novel inhibitor of these receptors. Biochemical kinetic studies using isolated Flk-1, FGF receptor 1, and PDGF receptor beta kinases revealed that SU6668 has competitive inhibitory properties with respect to ATP. Cocrystallographic studies of SU6668 in the catalytic domain of FGF receptor 1 substantiated the adenine mimetic properties of its oxindole core. Molecular modeling of SU6668 in the ATP binding pockets of the FIk-1/KDR and PDGF receptor kinases provided insight to explain the relative potency and selectivity of SU6668 for these receptors. In cellular systems, SU6668 inhibited receptor tyrosine phosphorylation and mitogenesis after stimulation of cells by appropriate ligands. Oral or i.p. administration of SU6668 in athymic mice resulted in significant growth inhibition of a diverse panel of human tumor xenografts of glioma, melanoma, lung, colon, ovarian, and epidermoid origin. Furthermore, intravital multifluorescence videomicroscopy of C6 glioma xenografts in the dorsal skinfold chamber model revealed that SU6668 treatment suppressed tumor angiogenesis. Finally, SU6668 treatment induced striking regression of large established human tumor xenografts. Investigations of SU6668 activity in cancer patients are ongoing in Phase I clinical trials.
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PMID:SU6668 is a potent antiangiogenic and antitumor agent that induces regression of established tumors. 1094 23

Angiogenesis is a significant prognostic factor in melanoma, but the angiogenic factors controlling the neovascularization are not well defined. The purpose of this study was to investigate whether the angiogenesis and metastasis of melanoma are promoted by vascular endothelial growth factor (VEGF), interleukin 8 (IL-8), platelet-derived endothelial cell growth factor (PD-ECGF), and/or basic fibroblast growth factor (bFGF). Cells from human melanoma lines (A-07, D-12, R-18, and U-25) transplanted to BALB/c nu/nu mice were used as tumor models. Expression of angiogenic factors was studied by ELISA, Western blotting, and immunohistochemistry. Angiogenesis was assessed by using an intradermal angiogenesis assay. Lung colonization and spontaneous lung metastasis were determined after i.v. and intradermal inoculation of tumor cells, respectively. The specific roles of VEGF, IL-8, PD-ECGF, and bFGF in tumor angiogenesis, lung colonization, and spontaneous metastasis were assessed in mice treated with neutralizing antibody. The melanoma lines expressed multiple angiogenic factors, and each line showed a unique expression pattern. Multiple angiogenic factors promoted angiogenesis in the most angiogenic melanoma lines, whereas angiogenesis in the least angiogenic melanoma lines was possibly promoted solely by VEGF. Tumor growth, lung colonization, and spontaneous metastasis were controlled by the rate of angiogenesis and hence by the angiogenic factors promoting the angiogenesis. Lung colonization and spontaneous metastasis in A-07 were inhibited by treatment with neutralizing antibody against VEGF, IL-8, PD-ECGF, or bFGF. Each of these angiogenic factors may promote metastasis in melanoma, because inhibition of one of them could not be compensated for by the others. Our observations suggest that efficient antiangiogenic treatment of melanoma may require identification and blocking of common functional features of several angiogenic factors.
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PMID:Vascular endothelial growth factor, interleukin 8, platelet-derived endothelial cell growth factor, and basic fibroblast growth factor promote angiogenesis and metastasis in human melanoma xenografts. 1098 9

Surgery, which is currently the only curative treatment for malignant melanoma, is suspected, in particular presentations, to induce adverse effects such as an increase of metastasis spread. A literature review was performed in order to examine the alleged causes of such phenomena. A medline search covering the 1985-1999 period was performed first. The chosen articles and the study of the references of each of them produced additional articles. The hypothesis is based on the alleged existence of tumor dormancy as micrometastates at an early stage of the disease. Surgery could induce metastasis spread directly by increasing the rate of circulating tumor cells and indirectly above all by disturbing complex mechanisms of tumor regulation such as the balance between activating and inhibiting factors of tumor angiogenesis. Surgery itself as well as the surgical stress could also make easier metastasis spread owing to antitumor immune mechanisms disturbance. Currently, there is no adequate evidence to induce a modified approach in the management of cutaneous melanoma. Surgery remains the mainstay of treatment. However, basic research on angiogenesis and immunity must be carried on.
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PMID:[Does surgery promote the development of metastasis in melanoma?]. 1098 24

Expression of thymidine phosphorylase (TP) is often associated with tumor angiogenesis and / or prognosis in patients. Further, infiltration of macrophages is closely correlated with the depth of tumor and angiogenesis in melanomas. In this study, we examined the expression of TP and an activated macrophage-specific enzyme, heme oxygenase-1 (HO-1), involved in malignancy in 22 cases with melanomas. TP was strongly expressed not only in CD68-positive macrophages in and around tumors, but also in S100 protein-positive melanoma cells, fibroblasts and keratinocytes. By contrast, HO-1 was specifically expressed in macrophages, but only slightly in melanoma cells and other cell types in the stroma of melanomas. We thus observed apparent co-expression of TP and HO-1 in macrophages infiltrating in the late stage of malignant melanomas. There appeared increasing numbers of TP-positive cells in Clark level IV and V melanoma compared with Clark level I (in situ) melanoma, and there was also a close correlation between numbers of TP-positive cells and HO-1-positive cells. Both TP- and HO-1-positive macrophages could be observed in the stroma in and around tumors in vertical growth melanomas.
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PMID:Co-expression of thymidine phosphorylase and heme oxygenase-1 in macrophages in human malignant vertical growth melanomas. 1101 Nov 18

The vascular endothelial growth factor is produced by a large variety of human tumors, including melanoma, in which it appears to play an important role in the process of tumor-induced angiogenesis. Little information is available on the role of placenta growth factor, a member of the vascular endothelial growth factor family of cytokines, in tumor angiogenesis, even though placenta growth factor/vascular endothelial growth factor heterodimers have been recently isolated from tumor cells. To investigate the role of placenta growth factor and vascular endothelial growth factor homodimers and heterodimers in melanoma angiogenesis and growth, 19 human melanoma cell lines derived from primary or metastatic tumors were characterized for the expression of these cytokines and their receptors. Release of placenta growth factor and vascular endothelial growth factor polypeptides into the supernatant of human melanoma cells was demonstrated. Reverse transcriptase polymerase chain reaction analysis showed the presence of mRNAs encoding at least three different vascular endothelial growth factor isoforms (VEGF(121), VEGF(165), and VEGF(189)) and transcripts for two placenta growth factor isoforms (PlGF-1 and PlGF-2) in human melanoma cells. In addition, placenta growth factor expression in human melanoma in vivo was detected by immunohistochemical staining of tumor specimens. Both primary and metastatic melanoma cells were found to express the mRNAs encoding for vascular endothelial growth factor and placenta growth factor receptors (KDR, Flt-1, neuropilin-1, and neuropilin-2), and exposure of melanoma cells to these cytokines resulted in a specific proliferative response, supporting the hypothesis of a role of these angiogenic factors in melanoma growth. J Invest Dermatol 115:1000-1007 2000
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PMID:Human melanoma cells secrete and respond to placenta growth factor and vascular endothelial growth factor. 1112 Nov 33

The established tumor is maintained through complex and poorly understood host-tumor interactions guiding processes such as angiogenesis. The numerous and diverse genetic alterations that accompany tumor genesis raises questions as to whether experimental cancer-promoting mutations remain relevant to tumor maintenance. Utilizing a new doxycycline-inducible H-RASV12G INK4a null mouse melanoma model, we have shown that melanoma genesis and maintenance are strictly dependent upon H-RASV12G expression. Withdrawal of doxycycline and H-RASV12G down-regulation resulted in clinical and histological regression of primary and explanted tumors. Moreover, the initial stages of regression were highlighted by dramatic activation of apoptosis in the tumor cells as well as host-derived endothelial cells. These data provide genetic evidence that H-RASV12G plays a critical role in tumor maintenance and tumor angiogenesis.
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PMID:An inducible melanoma model implicates a role for RAS in tumor maintenance and angiogenesis. 1119 Oct 50

New molecular factors have been characterized that are associated with the prognosis of prostate carcinoma patients, including p53 status and angiogenesis. We reported recently that mutant p53 (mp53) was associated with decreased expression of an endogenous inhibitor of angiogenesis, thrombospondin-1 (TSP-1), and increased microvessel density in melanoma and breast cancer. In this study, we performed a similar analysis on primary prostate carcinoma to determine whether these factors were associated with each other or patient outcomes. Paraffin-embedded specimens of 98 cases of primary prostate carcinoma were obtained and examined to confirm tissue diagnosis and Gleason scores. Carcinoma-specific levels of p53, TSP-1, and tumor angiogenesis were determined using semiquantitative immunohistochemistry (IHC) methods. Acquisition of mp53 was significantly associated with decreased TSP-1 (P = 0.002) and increased angiogenesis (P < 0.0001). An angiogenesis index integrating mp53, TSP-1, and angiogenesis (CD31) scores was found to be an independent predictor of survival in univariate and multivariate analyses that included Gleason score, clinical stage, and patient age. Further validation of the angiogenesis index in prostate carcinoma may provide a new tool to stratify patient risk.
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PMID:Independent association of angiogenesis index with outcome in prostate cancer. 1120 22


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