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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiogenesis is essential for tumor progression and metastasis, however, the angiogenesis regulators that are biologically relevant for human melanoma are still unknown. In this study, we analyzed the expression of the potent angiogenic factor angiogenin (ANG) in human melanoma in vitro and in vivo. Four different human melanoma cell lines and two normal melanocytes were kept either under normoxic or hypoxic conditions. After 24 h of hypoxic culture conditions, ANG was up-regulated in the melanoma cell lines but not in normal melanocytes. Induction levels correlated with the metastatic potential of the cell lines. These data were confirmed by Northern blot analysis. In contrast, induction of vascular endothelial growth factor by hypoxia was equally strong in the examined highly aggressive melanoma cell lines and in one nonaggressive cell line. Other angiogenic factors tested as well as the melanoma growth stimulatory activity (Gro-alpha) showed no up-regulation. Thus, in the present study, hypoxia-induced up-regulation in melanoma cells was only observed for ANG and vascular endothelial growth factor. Immunohistochemical studies showed that 8 of 10 melanomas and all 15 metastases were positive for ANG, particularly in the vicinity of small vessels, whereas all benign nevi were negative. Reverse transcription-PCR detected only weak ANG mRNA in nevi but strong signals in primary melanomas and metastases. In conclusion, we demonstrate for the first time enhanced expression of ANG in highly metastatic cell lines as well as in melanomas and metastases in vivo, suggesting that ANG expression is associated with the metastatic potential.
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PMID:Hypoxia-induced up-regulation of angiogenin in human malignant melanoma. 1019 32

Although initiating mutations in the ret protooncogene have been found in familial and sporadic medullary thyroid carcinoma (MTC), the molecular events underlying subsequent tumor progression stages are unknown. We now report that changes in trk family neurotrophin receptor expression appear to be involved in both preneoplastic thyroid C cell hyperplasia and later tumor progression. Only a subset of normal C cells expresses trk family receptors, but, in C cell hyperplasia, the affected cells consistently express trkB, with variable expression of trkA and trkC. In later stages of gross MTC tumors, trkB expression was substantially reduced, while trkC expression was increased and often intense. In a cell culture model of MTC, exogenous trkB expression resulted in severely impaired tumorigenicity and was associated with 11-fold lower levels of the angiogenesis factor vascular endothelial growth factor. These results suggest that trk family receptor genes participate in MTC development and progression, and, in particular, that trkB may limit MTC tumor growth by inhibition of angiogenesis.
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PMID:Roles of trk family neurotrophin receptors in medullary thyroid carcinoma development and progression. 1020 Feb 98

Angiogenesis is essential for tumor progression and metastasis. It is mediated by the release of angiogenic factors by the tumor or host. We analyzed the expression of angiogenic factors by the prostate cancer cell line LNCaP and two derived variants, in vitro and in vivo, to determine whether metastatic cell lines express higher levels of these factors. The production of three angiogenic factors, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and interleukin 8 (IL-8), by LNCaP and its variants, LNCaP-LN3 (highly metastatic) and LNCaP-Pro5 (slightly metastatic), was measured by ELISA. VEGF, bFGF, and IL-8 mRNA expression was determined in vitro by Northern blot analysis. VEGF mRNA expression was determined in vivo by in situ hybridization. VEGF and flk-1 protein expression and microvessel density of LNCaP cell tumors were quantified by immunohistochemistry. In vitro, VEGF production by LNCaP-LN3 (3.15+/-0.04 pg/ml/10(3) cells) was significantly higher than those of both LNCaP (2.38+/-0.34 pg/ml/10(3) cells) and LNCaP-Pro5 (1.67+/-0.37 pg/ml/10(3) cells; P = 0.049 and 0.001, respectively). None of the three cell lines produced detectable levels of bFGF or IL-8 in vitro. In vivo, LNCaP-LN3 tumors exhibited higher levels of VEGF mRNA and protein (152.2+/-28.5 and 200.5+/-28.3) and of flk-1 protein (156.5+/-20.6) and had higher microvessel density (16.4+/-4.2) than either LNCaP tumors (89+/-17.5, 173.3+/-23.0, 124.6+/-21.6, and 12.4+/-3.5, respectively) or LNCaP-Pro5 tumors (63+/-14.7, 141.2+/-38.1, 126.1+/-20, and 5.8+/-2.2, respectively). In conclusion, metastatic human prostate cancer cells exhibited enhanced VEGF production and tumor vascularity compared with prostate cancer cells of lower metastatic potential. Thus, VEGF may play an important role in prostate cancer metastasis.
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PMID:Highly metastatic human prostate cancer growing within the prostate of athymic mice overexpresses vascular endothelial growth factor. 1021 13

Ovarian cancer is a richly vascularized neoplasm with solid and cystic components. The purpose of this study was to determine whether cyst fluid could be used to quantitatively evaluate production of angiogenic factors in ovarian lesions. ELISA was used to measure vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in the cyst fluid of patients with ovarian cancer (n = 13), benign cysts and cystadenomas (n = 23), borderline tumors (n = 5), and functional cysts (n = 8). VEGF levels were markedly elevated in the fluid of malignant cysts (38.5+/-8.2 ng/ml) as compared with benign (1.6+/-0.4 ng/ml; P < 0.001), borderline (5.7+/-1.5 ng/ml; P < 0.001), or functional cysts (3.8+/-2.0 ng/ml; P < 0.001). The presence of VEGF in cancer cells was confirmed by immunohistochemistry. Follow-up of patients with malignant and borderline lesions demonstrated a correlation between VEGF levels in cyst fluid and tumor recurrence (P = 0.03). bFGF in malignant cysts was either undetectable or very low (0.3+/-0.2 ng/ml), and no significant differences were found in bFGF levels among malignant, benign, borderline, and functional cysts. This study demonstrates that ovarian malignancy is associated with dramatic elevation of VEGF levels in ovarian cyst fluid. Conversely, there is no correlation between cyst fluid bFGF levels and malignant transformation. The high levels of VEGF in malignant cysts are consistent with the hypothesis that this growth factor plays an important role in ovarian cancer related-angiogenesis and tumor progression and represents a potentially important target of antiangiogenic therapy.
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PMID:Vascular endothelial growth factor levels in ovarian cyst fluid correlate with malignancy. 1021 18

A central issue in the study of neoplastic transformation is to understand how proto-oncogene products deregulate normal processes of cell growth and differentiation: an intrinsic aspect of this is to probe the sequence of events leading to altered expression of proto-oncogenes. In the past few years, studies aimed at understanding the regulation and function of protein synthesis initiation factors, eIF4E initially, culminated in the unexpected finding that a moderate overexpression of this factor results in dramatic phenotypic changes, including rapid proliferation and malignant transformation. Conversely, the tumorigenic properties of cancer cells can be strongly inhibited by antisense-RNA against eIF4E, or overexpression of the inhibitory proteins: 4E-BPs. Furthermore, eIF4E is elevated in carcinomas of the breast, head and neck (HNSCC) and prostate, but not in typical benign lesions. This is a strong indication that elevated eIF4E expression may mark a critical transition in cancer progression. Establishing a greater protein synthesis output may be a necessary step for cancer cells in order to sustain their rapid proliferation. However, analysis of cells transformed by eIF4E revealed that the synthesis of only a few proteins was greatly enhanced, while synthesis of most was minimally increased. One possible explanation is that eIF4E causes these effects by specifically increasing the translational efficiency of several oncogene transcripts, leading to overexpression of their products. The feasibility of this hypothesis was confirmed experimentally with the identification of several important products that are specifically upregulated in eIF4E-overexpressing cells. These include: c-Myc, cyclin DI and ODC, which control cycle progression and tumorigenesis; basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF), which are powerful promoters of cell growth and angiogenesis. A deeper understanding of the mRNAs that are strongly dependent on excess eIF4E/F for efficient translation will eventually result in fuller understanding of the fundamental role of translational control in different pathophysiological conditions, including malignancy.
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PMID:eIF4E expression in tumors: its possible role in progression of malignancies. 1021 44

Substantial experimental and clinical evidence links tumor growth, progression and metastatic potential with neoangiogenesis. This process is modulated by several angiogenic growth factors, such as vascular endothelial growth factor (VEGF). Little data are currently available on serum VEGF levels in cancer patients. In the present retrospective investigation preoperative serum VEGF was higher in 53 patients with epithelial ovarian cancer than in 25 patients with benign ovarian disease as controls (median, range: 229.7, 23.5-1807.5 pg/ml versus 140.3, 14.7-1038.7 pg/ml, p = 0.034). With regard to FIGO stage, antigen values were significantly elevated in stage III-IV (p = 0.027) but not in stage I-II ovarian cancer patients when compared to controls. In patients with advanced disease preoperative serum VEGE was significantly related to the presence of ascites (p = 0.013), but not to common prognostic variables, response to chemotherapy and survival. In conclusion, preoperative serum VEGF assay reflects tumor progression and ascites generation in epithelial ovarian cancer, but it seems to have a limited predictive and prognostic value in patients with advanced disease.
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PMID:Serum preoperative vascular endothelial growth factor (VEGF) in epithelial ovarian cancer: relationship with prognostic variables and clinical outcome. 1036 13

Melanoma cells constitutively release intercellular adhesion molecule 1 (ICAM-1) as soluble ICAM-1 (sICAM-1), and its levels are elevated in melanoma patients and correlate with disease progression. However, this correlation is not absolute, suggesting that specific characteristics of neoplastic cells and/or ICAM-1-positive non-neoplastic cells may influence the amounts of circulating sICAM-1. In this study, we found a weak correlation (r = 0.55; r2 = 0.3) between sICAM-1 release by 40 metastatic melanomas (36 primary cultures and 4 cell lines), and ICAM-1 expression on neoplastic cells. In addition, melanoma-secreted interleukin-1alpha (IL-1alpha) (1/40) but not vascular endothelial growth factor (VEGF) (29/40), significantly (P < 0.05) up-regulated the shedding of sICAM-1 by human umbilical vein endothelial cells (HUVEC). This was completely abolished by IL-1alpha/beta neutralizing antibodies both at the protein and mRNA level. Altogether, our results suggest that (i) the extent of sICAM-1 release is distinctive for individual melanomas and can be independent of ICAM-1 expression; (ii) tumor endothelia may sustain levels of sICAM-1 in selected melanomas; (iii) melanoma-released VEGF does not affect ICAM-1 expression and sICAM-1 release by HUVEC. Melanoma-derived sICAM-1 inhibits cell-mediated cytotoxicity of melanoma cells; therefore, constitutive levels of sICAM-1 release and IL-1alpha secretion by individual melanomas can differentially influence tumor progression and the clinical effectiveness of cytotoxic-cell-based vaccines.
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PMID:In vitro analysis of the melanoma/endothelium interaction increasing the release of soluble intercellular adhesion molecule 1 by endothelial cells. 1041 67

Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding glucose transporters, glycolytic enzymes, vascular endothelial growth factor, and other proteins involved in O2 homeostasis and tumor progression. The expression and transcriptional activity of the HIF-1alpha subunit is regulated by the cellular O2 concentration. We demonstrate that insulin, insulin-like growth factor (IGF)-1, and IGF-2 induce expression of HIF-1alpha, which is required for expression of genes encoding IGF-2, IGF-binding protein (IGFBP)-2 and IGFBP-3. These data provide a novel mechanism by which HIF-1alpha overexpression may occur in tumor cells and contribute to an autocrine growth factor loop.
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PMID:Reciprocal positive regulation of hypoxia-inducible factor 1alpha and insulin-like growth factor 2. 1046 82

Neovascularization and increased glycolysis, two universal characteristics of solid tumors, represent adaptations to a hypoxic microenvironment that are correlated with tumor invasion, metastasis, and lethality. Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding glucose transporters, glycolytic enzymes, and vascular endothelial growth factor. HIF-1 transcriptional activity is determined by regulated expression of the HIF-1alpha subunit. In this study, HIF-1alpha expression was analyzed by immunohistochemistry in 179 tumor specimens. HIF-1alpha was overexpressed in 13 of 19 tumor types compared with the respective normal tissues, including colon, breast, gastric, lung, skin, ovarian, pancreatic, prostate, and renal carcinomas. HIF-1alpha expression was correlated with aberrant p53 accumulation and cell proliferation. Preneoplastic lesions in breast, colon, and prostate overexpressed HIF-1alpha, whereas benign tumors in breast and uterus did not. HIF-1alpha overexpression was detected in only 29% of primary breast cancers but in 69% of breast cancer metastases. In brain tumors, HIF-1alpha immunohistochemistry demarcated areas of angiogenesis. These results provide the first clinical data indicating that HIF-1alpha may play an important role in human cancer progression.
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PMID:Overexpression of hypoxia-inducible factor 1alpha in common human cancers and their metastases. 1058 6

Hepatocyte growth factor (HGF), also known as scatter factor (SF), is known to act on cancer cells as well as endothelial cells and stimulate angiogenesis, thus playing an unwanted role in the development and progression of cancer. The current study examined the effects of a newly discovered HGF variant, NK4, on angiogenesis in vitro. Chemically generated NK4 (from recombinant human HGF/SF) was found to be able to inhibit HGF-induced activation (tyrosine phosphorylation) of the HGF/SF receptor cMET but was itself unable to activate cMET. Furthermore, NK4 was demonstrated to inhibit tubule formation from human umbilical vein endothelial cells that was induced by both HGF/SF and a HGF/SF-producing fibroblast (MRC5). Under the same settings, NK4 failed to increase tubular formation. NK4 had no effects on interleukin 8- and vascular endothelial growth factor-induced tubule formation. Using computer-assisted motion analysis, it was further shown that NK4 inhibited HGF-induced migration of human umbilical vein endothelial cells in a migration assay and in an endothelial wounding assay. These data show that NK4 is a complete antagonist to HGF. It inhibits HGF-induced endothelial movement and tubule formation. Thus, NK4 may have an important bearing on the control of cancer progression through its role in angiogenesis. Additional in vivo studies are warranted.
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PMID:Antagonistic effect of NK4, a novel hepatocyte growth factor variant, on in vitro angiogenesis of human vascular endothelial cells. 1058 89


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