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Query: UMLS:C0006826 (cancer)
 1,092,456 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Platelet-derived growth factor and phorbol ester cause an increase in vascular endothelial growth factor (VEGF) mRNA expression in control NIH 3T3 fibroblasts and NIH 3T3 fibroblasts overexpressing human protein kinase C (PKC) alpha. In the case of phorbol ester-induced VEGF expression, the VEGF mRNA levels were significantly higher in cells overexpressing human PKC alpha as compared to control cells. In cells stimulated with platelet-derived growth factor or phorbol ester, induction of expression was lost after down-regulation of PKC. This indicates that PKC is involved in the signal transduction leading to VEGF expression.
Cancer Res 1992 Sep 01
PMID:Platelet-derived growth factor-induced transcription of the vascular endothelial growth factor gene is mediated by protein kinase C. 151 46

The presence of mRNAs for vascular endothelial growth factor (VEGF) and a VEGF-related protein, placenta growth factor (PIGF) was examined in 29 cases of renal cell carcinoma tissues and adjacent normal kidney tissues and in 4 human renal cell carcinoma cell lines. Northern blot analysis showed that 26 of 27 hypervascular renal cell carcinoma tissues (96%) exhibited a markedly elevated level (3-13 fold) of VEGF mRNA compared to the adjacent normal kidney tissues. Even tumors of small size, whenever they were hypervascular, overexpressed VEGF mRNA. We also demonstrated that mRNA for PIGF was expressed in 21 of 23 hypervascular renal cell carcinoma tissues (91%) but was not detected in the adjacent normal kidney tissues. Two hypovascular carcinoma tissues neither overexpressed VEGF mRNA nor had PIGF mRNA. VEGF mRNA was detected in four human renal cell carcinoma cell lines, while PIGF mRNA was not. There was no difference in the level of basic fibroblast growth factor mRNA between tumor tissues and normal kidney tissue, although our previous study demonstrated elevated basic fibroblast growth factor protein in the serum of renal cell carcinoma patients (K. Fujimoto et al., Biochem. Biophys. Res. Commun., 180: 386-392, 1991). Taken together, these results suggest that VEGF, PIGF, and basic fibroblast growth factor are cooperatively working to increase the angiogenesis in renal cell carcinoma in vivo.
Cancer Res 1994 Aug 01
PMID:Markedly increased amounts of messenger RNAs for vascular endothelial growth factor and placenta growth factor in renal cell carcinoma associated with angiogenesis. 751 52

Recent studies demonstrate the relationship of microvessel density to malignant progression in breast cancer (N. Weidner, J. P. Semple, W. R. Welch, and J. Folkman, N. Engl. J. Med., 324: 1-8, 1991), underscoring the importance of angiogenesis in this tumor. Crucial in tumor angiogenesis are the paracrine actions of tumor-secreted factors (e.g., vascular endothelial growth factor), which have been thought to derive from the tumor epithelial cells themselves. We demonstrate that in response to hypoxic conditions, human mammary fibroblasts dramatically up-regulate vascular endothelial growth factor mRNA and increase vascular endothelial growth factor protein levels in accordance with the degree of oxygen deprivation. Thus, mammary stromal cells, only recently considered in the regulation of breast carcinomas, may play a hitherto unrealized role in breast cancer angiogenesis.
Cancer Res 1994 Dec 01
PMID:Mammary fibroblasts may influence breast tumor angiogenesis via hypoxia-induced vascular endothelial growth factor up-regulation and protein expression. 752 53

We have previously suggested that tumor angiogenesis in human gliomas is regulated by a paracrine mechanism involving vascular endothelial growth factor (VEGF) and flt-1 (VEGF-receptor 1). VEGF, an endothelial-cell-specific mitogen, is abundantly expressed in glioma cells which reside along necrotic areas, whereas flt-1, a tyrosine-kinase receptor for VEGF, is expressed in tumor endothelial cells, but not in endothelial cells in normal adult brain. Recently, a second tyrosine-kinase receptor which binds VEGF with high affinity, designated KDR or flk-1, has been described. We performed in situ hybridization for VEGF mRNA, flt-1 mRNA and KDR mRNA on serial sections of normal brain, low-grade and high-grade glioma specimens. We show that KDR mRNA is co-expressed with flt-1 in vascular cells in glioblastoma but not in low-grade glioma. Since flt-1 and KDR are not expressed in endothelial cells in the normal adult brain, the coordinate up-regulation of 2 receptors for VEGF appears to be a critical event which controls tumor angiogenesis. Immunocytochemistry with a monoclonal anti-VEGF antibody revealed significant amounts of VEGF protein in the same glioma cells that expressed VEGF mRNA. The largest amount of VEGF immunoreactivity, however, was detected on the vasculature of glioblastomas, the site where VEGF exerts its biological functions. These findings suggest that VEGF is produced and secreted by glioma cells and acts on tumor endothelial cells which express VEGF receptors. To further characterize VEGF-producer cells in vivo, we investigated cellular proliferation, immunoreactivity to the p53 tumor-suppressor gene product and epidermal-growth-factor-receptor (EGFR) expression on serial sections by immunocytochemistry. VEGF-producer cells did not show increased cellular proliferation, p53 immunoreactivity or EGFR immunoreactivity as compared with glioma cells which did not express VEGF. Our studies therefore do not demonstrate evidence for a growth advantage of VEGF-producer cells in vivo or VEGF induction by p53 mutation or EGFR over-expression.
Int J Cancer 1994 Nov 15
PMID:Vascular endothelial growth factor and glioma angiogenesis: coordinate induction of VEGF receptors, distribution of VEGF protein and possible in vivo regulatory mechanisms. 752 92

Angiogenesis is an independent prognostic indicator in breast cancer. In this report, the relationship between expression of vascular endothelial growth factor (VEGF; a selective mitogen for endothelial cells) and the microvessel density was examined in 103 primary breast cancers. The expression of VEGF was evaluated by immunocytochemical staining using anti-VEGF antibody. The microvessel density, which was determined by immunostaining for factor VIII antigen, in VEGF-rich tumors was clearly higher than that in VEGF-poor tumors (P < 0.01). There was a good correlation between VEGF expression and the increment of microvessel density. Furthermore, postoperative survey demonstrated that the relapse-free survival rate of VEGF-rich tumors was significantly worse than that of VEGF-poor tumors. It was suggested that the expression of VEGF is closely associated with the promotion of angiogenesis and with early relapse in primary breast cancer.
Jpn J Cancer Res 1994 Oct
PMID:Association of vascular endothelial growth factor expression with tumor angiogenesis and with early relapse in primary breast cancer. 752 23

We have investigated by RNase protection analysis the expression of 2 angiogenic factors in 45 primary bladder tumors and 8 normal bladders. Expression of vascular endothelial growth factor (VEGF) was 3-fold higher and that of platelet-derived endothelial cell growth factor was 40-fold higher in tumors compared to normal bladder. However, the factors were differentially expressed in different stages of the cancer. Expression of VEGF in superficial tumors was 4-fold higher than in invasive tumors and 10-fold higher than in normal bladder (superficial versus invasive, P < 0.0006; superficial versus normal, P < 0.0002). Expression of platelet-derived endothelial cell growth factor in invasive tumors was 33-fold higher than in superficial tumors and 260-fold higher than in normal bladder (invasive versus superficial, P < 0.0001; invasive versus normal, P < 0.0003). In well differentiated or moderately differentiated superficial tumors which had invaded the lamina propria (pT1G1/2) VEGF expression was 4-fold higher in tumors which subsequently recurred at 3 months compared to those which did not recur (P < 0.002). Thus there are two distinct angiogenic pathways involved in different stages of bladder cancer, which is in keeping with the evidence for two different genetic pathways. Elevated VEGF expression predicts early recurrence of pT1G1/2 tumors.
Cancer Res 1995 Feb 01
PMID:Different angiogenic pathways characterize superficial and invasive bladder cancer. 753 May 95

To examine which growth factors correlate with neovascularization in human brain tumors, the mRNA levels of transforming growth factor alpha, transforming growth factor beta, basic fibroblast growth factor, and vascular endothelial growth factor (VEGF) genes were determined by a Northern blot analysis in surgically obtained human gliomas and meningiomas. The vascular development was determined by counting the number of microvessels which were immunostained with von Willebrand factor. We normalized the growth factor mRNA levels versus the glyceraldehyde phosphate dehydrogenase mRNA level. In the 17 gliomas and 16 meningiomas examined, the mRNA of transforming growth factors alpha and beta, basic fibroblast growth factor, and VEGF were expressed at various levels. Among those 4 growth factors, the mRNA levels of VEGF, but not those of transforming growth factors alpha and beta and basic fibroblast growth factor, correlated significantly with vascularity in both gliomas (correlation coefficient r = 0.499; P < 0.05) and meningiomas (correlation coefficient r = 0.779; P < 0.001). These findings thus suggest that VEGF may be a positive factor in tumor angiogenesis in both human gliomas and meningiomas.
Cancer Res 1995 Mar 01
PMID:Expression of vascular endothelial growth factor and its possible relation with neovascularization in human brain tumors. 753 45

Capillary hemangioblastoma is the most frequent manifestation of the autosomal dominantly inherited von Hippel-Lindau (VHL) disease but also presents as a nonfamilial, sporadic vascular tumor. Hemangioblastomas are characterized by a dense network of capillaries in association with cysts. To investigate the mechanisms underlying neovascularization and cyst formation, we analyzed eight VHL disease-associated and five sporadic hemangioblastomas. Histologically, both tumor types showed a similar phenotype. The capillaries expressed the endothelial cell markers von Willebrand factor and CD31 antigen. We investigated the expression of vascular endothelial growth factor (VEGF), an endothelial cell-specific mitogen which is also known to induce vascular permeability in vivo, and its high affinity tyrosine kinase receptors flt-1 and KDR. Northern blot and in situ hybridization analysis revealed significant up-regulation of VEGF and VEGF receptor expression in VHL disease-associated and sporadic hemangioblastomas compared to normal brain and tumor stromal cells as sites of abundant VEGF transcription. Endothelial cells did not express detectable amounts of VEGF mRNA but coexpressed flt-1 and KDR. By immunohistochemistry, VEGF protein was detectable in the tumor interstitium and was found to be concentrated around capillaries. Performing reverse transcription-PCR, we demonstrated that VEGF121 and VEGF165 were the splice variants predominantly expressed, whereas mRNA encoding VEGF189 was present at smaller amounts. Our findings suggest that, in VHL disease-associated and sporadic hemangioblastomas, VEGF121 and VEGF165 are secreted by stromal cells and interact with the corresponding VEGF receptors expressed on tumor endothelial cells. This paracrine mechanism may mediate neovascularization and cyst formation in capillary hemangioblastomas.
Cancer Res 1995 Mar 15
PMID:Up-regulation of vascular endothelial growth factor and its receptors in von Hippel-Lindau disease-associated and sporadic hemangioblastomas. 753 61

Conditioned media (CM) harvested from human pulmonary squamous cell carcinoma (QG56), pulmonary small cell carcinoma (QG90) and gastric adenocarcinoma (MKN28) cultivated under hypoxic conditions (3% oxygen), enhanced the angiogenic activity in vitro more than those obtained under normoxic cultivation (20% oxygen). The total length of the tube structures formed by bovine capillary endothelial cells (BCEs) in the CM cultured at 3% oxygen was about 1.5 (QG56 and MKN28) or 1.9 (QG90) times longer than that at 20% oxygen. Tube formation was diminished by the preincubation of CM with anti-basic fibroblast growth factor (bFGF) IgG. After performing the fractionations of the CM and the crude extracts of cell lysates cultured using a heparin-Sepharose column, the mitogenic activity in the CM from all cancer cells at 3% oxygen was about twice that of CM at 20% oxygen, while it decreased in the cell lysates at 3% oxygen to about 40% of those at 20% oxygen. This mitogenic activity of BCEs in the CM from all cancer cells was almost totally suppressed by anti-bFGF IgG, but not with anti-vascular endothelial growth factor IgG. Hypoxia is an important factor in tumor angiogenesis by bFGF or bFGF-like molecule(s) derived from tumour cells.
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PMID:Conditioned media of carcinoma cells cultured in hypoxic microenvironment stimulate angiogenesis in vitro; relationship to basic fibroblast growth factor. 753 65

Magnetic resonance imaging has been used to follow noninvasively tumor neovascularization and tumor growth in a model system of multicellular C6 rat glioma spheroids implanted s.c. in nude mice. By positioning a single spheroid approximately 1 cm from the site of incision both the vascularization of the tumor and the wound healing processes were spatially separated and could be simultaneously followed. The model proposed here provides defined initial conditions of tumor geometry and cell proliferative status and separation of initial tumor growth from neovascularization. Magnetic susceptibility relaxation provided an intrinsic marker for blood containing vessels. The implanted spheroid induced vessel growth within 4 days after implantation that was geometrically oriented toward the spheroid and distinct from wound healing at the site of incision. Volume measurements showed a corresponding 4-day lag in growth followed by Gompertz progression. Sham implantation of agarose beads of similar diameter showed no induction of vessel growth, ruling out a direct effect of wound healing. The new vessels penetrating the tumor were highly permeable to the contrast reagent gadolinium-diethylenetriaminepentaacetic acid. This permeability may be due to the action of vascular endothelial growth factor, a major angiogenic growth factor in this system, and a potent permeability factor.
Cancer Res 1995 May 01
PMID:Neovascularization induced growth of implanted C6 glioma multicellular spheroids: magnetic resonance microimaging. 753 76


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