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M Ziche

Publications and source records attributed to M Ziche.

At least 55 records · Page 3Linked to original sources
PubMed1997

Distinct capillary density and progression promoted by vascular endothelial growth factor-A homodimers and heterodimers.

The aim of this study was to characterize the capillary density, progression and persistence of new capillaries induced by different isoforms of vascular endothelial growth factor (VEGF)-A. They were produced and purified using the same protocol and assessed in the same experimental model, the rabbit cornea assay. Monogenic homodimers for VEGF121 and VEGF165 together with the heterodimer VEGF121/165 were tested as slow release polymer pellets implanted into the avascular rabbit cornea and examined up to 18 days post-implantation. The implants consistently stimulated angiogenesis in the absence of inflammation. The VEGF121 isoform produced the strongest increase of new capillary vessels which rapidly and persistently progressed into the corneal stroma. VEGF165 promoted the growth of a smaller number of capillaries which ten-ded to regress over time. Heterodimers of VEGF121/165 produced intermediate in vivo activities between the two homodimers. In vitro endothelial cell proliferation, mobilization and adhesion were promoted by all VEGF isoforms under serum-free or serum-reduced conditions with the same order of potency. Anti-soluble KDR (sKDR) antibody completely inhibited the effects of all the isoforms. These results indicate that monogenic homodimer preparations of VEGF121 and VEGF165 can display distinct biological effects which are functionally retained after the heterodimeric assembly of VEGF121 and VEGF165. The observed different biological behavior of the VEGF isoforms reveals the possibility that in vivo the assembly of dimers derived from splicing of a single gene may yield molecules with either different matrix or receptor interaction, stability or diffusion rate according to specific needs.

Journal Article↗
PubMed1997

Vasorelaxant effects induced by the antiangiogenic drug linomide in aortic and saphenous vein preparations of the rabbit.

1. Linomide (N-phenylmethyl-1,2-dihydro-4-hydroxyl-1-methyl-2-oxoquinoline-3-carb oxa mide) inhibits vascular proliferation and has been proposed as an antiangiogenic drug. We have investigated the vascular effect of linomide in rabbit aortic and saphenous vein ring preparations and in rat cultured vascular smooth muscle cells (VSMCs). 2. Linomide (25-300 micrograms ml-1) did not alter the basal tone of the preparations. The drug induced a concentration-dependent relaxant effect in aortic rings with endothelium, preconstricted by noradrenaline (NA), 5-hydroxytryptamine (5-HT) and by the thromboxane mimetic U46619. 3. The degree of relaxation induced by linomide was significantly reduced by exposure to the cyclooxygenase inhibitors indomethacin (3 microM) and acetylsalicylic acid (500 microM), and was not influenced by pretreatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) (100 microM) in aortic rings with endothelium, preconstricted with NA. 4. Endothelium removal significantly reduced the relaxant response to linomide in aortic ring preparations. 5. A concentration-dependent relaxant response was observed also in rabbit saphenous vein preparations deprived of endothelium and preconstricted either by NA or U46619. The degree of relaxation obtained in a high potassium solution was consistently smaller than that observed in NA-pretreated venous preparations. 6. The vasorelaxant effect of linomide was consistently blunted by the adenylate cyclase inhibitor SQ 22536 (50 microM), both in intact aortic rings and in those deprived of endothelium. 7. In rat cultured vascular smooth muscle cells, linomide (100-200 micrograms ml-1) induced a significant increase in cyclic AMP levels, which was blocked by exposure to 50 microM SQ 22536. 8. In endothelium-deprived aortic ring preparations, the linomide-induced relaxant effect was greatly reduced in high potassium medium (KCl = 25 mM). Pretreatment with the ATP potassium channel inhibitor glibenclamide (3 microM) significantly reduced the linomide-induced relaxation. 9. The results show that linomide possesses a vasorelaxant effect which is attributable to both endothelium-dependent and -independent properties. While the former component of the drug's activity is apparently due to the release of a prostanoid from endothelial cells, the endothelium-independent mechanism involved in linomide relaxation is linked to cyclic AMP accumulation and to ATP-sensitive potassium channel activation in VSMCs.

Animals↗
PubMed1997

Nitric oxide promotes proliferation and plasminogen activator production by coronary venular endothelium through endogenous bFGF.

We reported previously that NO is responsible for the angiogenesis produced by endothelium-dependent vasodilating peptides. To investigate the mechanisms by which NO controls angiogenesis, NO was assessed for the ability to affect cell proliferation and upregulation of urokinase-type plasminogen activator (uPA) induced by basic fibroblast growth factor (bFGF) when added exogenously to or when produced endogenously by coronary venular endothelial cells (CVECs). The treatment of the cells with the NO donor sodium nitroprusside (NaNp) induced uPA upregulation and cell proliferation, which were prevented by anti-bFGF antibodies. Similarly, the NO-dependent mitogenic activity of the vasodilating peptide substance P (SP) was blocked by anti-bFGF antibodies, thus implicating endogenous bFGF in the NO-induced response. NaNp and SP induced bFGF expression as measured by Western blot analysis of CVEC extracts and by differential reverse transcriptase-polymerase chain reaction of bFGF mRNA. SP-induced upregulation of bFGF was prevented by the NO synthase inhibitor N omega-monomethyl-L-arginine. We conclude that NO promotes cell proliferation and uPA upregulation in CVECs by inducing endogenous bFGF and that this pathway mediates the angiogenetic response to the vasoactive neuropeptide SP. This signaling paradigm may provide an important link between shear rate, NO, bFGF, and coronary angiogenesis.

Cell Division↗
PubMed1997

The activin-binding protein follistatin regulates autocrine endothelial cell activity and induces angiogenesis.

Increasing evidence suggests that autocrine endothelial cell activity contributes significantly to the angiogenic cascade once the endothelial cells are initially activated by exogenous stimuli. We have employed the differential RNA-display technique to identify endothelial cell genes that are expressed under autocrine control as a result of the cells' release from growth arrest. Among the differentially expressed genes was the activin-binding and- neutralizing glycoprotein follistatin (FS), which was expressed by migrating endothelial cells and down-regulated once the cells had reached growth arrest. Cytokine exposure identified FS as a basic fibroblast growth factor (bFGF)-inducible gene. In contrast, activin-beta A, an inhibitor of endothelial cell proliferation, was constitutively expressed by migrating and resting endothelial cells. Exogenous recombinant FS induced proliferation of human umbilical vein endothelial cells and low bFGF-expressing bovine aortic endothelial cells. In vivo, FS was moderately angiogenic in the rabbit cornea. However, FS implantation in the cornea in combination with subcritical concentrations of bFGF induced a strong angiogenic response. The data demonstrate that FS by itself and particularly in synergy with bFGF induces angiogenesis. Furthermore, differential expression by endothelial cells suggests a critical role of the FS/activin-beta A system in regulating autocrine endothelial cell activity.

Amino Acid Sequence↗
PubMed1997

Placenta growth factor-1 is chemotactic, mitogenic, and angiogenic.

The placental-derived growth factor (PIGF) is a dimeric glycoprotein showing a high degree of sequence similarity to the vascular endothelial growth factor. Alternative splicing of the PIGF primary transcript gives rise to two forms, named PIGF-1 and PIGF-2, which differ only in the insertion of a highly basic 21-amino acid stretch at the carboxyl end. The presence of the PIGF mRNA in thyroid, placenta, lung, and goiter has indicated the tissues where this factor functions. However, the role of PIGF in vascular development has not yet been clearly established. In the present study, we described the purification of PIGF-1 from overexpressing eukaryotic cells and then measured the angiogenic activity of the purified PIGF-1 in vivo in the rabbit cornea and the chick chorioallantoic membrane assays. In both in vivo assays, PIGF-1 induced a strong neovascularization process that was blocked by affinity-purified anti-PIGF-1 antibody. In the avascular cornea, PIGF-1 induced angiogenesis in a dose-dependent manner and seemed to be at least as effective (if not more effective) than vascular endothelial growth factor and basic fibroblast growth factor under the same conditions and at the same concentration. PIGF-1 was shown to induce cell growth and migration of endothelial cells from bovine coronary postcapillary venules and from human umbilical veins. In these two in vitro assays, PIGF-1 seemed to have a comparable effect to that of vascular endothelial growth factor and basic fibroblast growth factor on the cultured microvascular endothelium (eg, capillary venule endothelial cells). In summary, this is the first study to demonstrate that PIGF-1 can induce angiogenesis in vivo and stimulate the migration and proliferation of endothelial cells in vitro.

Allantois↗
PubMed1996

HIV-tat protein is a heparin-binding angiogenic growth factor.

Transgenic animal studies have linked the expression of the HIV-1 tat gene to the appearance of Kaposi's sarcoma (KS)-like lesions. We have recently shown that recombinant tat is angiogenic in vivo, and that tat angiogenic response is enhanced by heparin. Also in the rabbit cornea model, recombinant HIV-1 tat alone is poorly angiogenic, but gives a good response when combined with heparin. Like many angiogenic growth factors, tat has a basic domain similar to that of several heparin binding angiogenic factors, including FGF, VEGF and HGF, suggesting that this region is important in endothelial cell activation. We show that tat binds heparin sepharose with a high affinity, similar to bFGF. Binding of tat to the cell surface is also modulated by heparin. Biological activities of tat, such as induction of endothelial cell growth, migration and invasion in vitro are all enhanced by low concentrations and inhibited by high concentrations of heparin, as has been shown for other heparin-binding angiogenic factors. Heparan sulfate is also effective, whereas the unsulfated polysaccharide K5 does not enhance tat activity. Furthermore, a peptide encompassing the tat basic domain is able to induce growth and migration of endothelial cells, while an adjacent peptide is not. Our data indicate that the tat basic domain plays a key role in its vascular cell activation properties, and strongly suggest that extracellular HIV-tat is essentially a 'new' heparin-binding angiogenic factor.

Amino Acid Sequence↗
PubMed1996

The tachykinin NK1 receptor mediates the migration-promoting effect of substance P on human skin fibroblasts in culture.

Fibroblast migration is an important component of the tissue response during the repair process, and substance P (SP) has been shown to exert trophic effects. In the present study, cell migration was evaluated as the distance travelled by adherent human skin fibroblasts (HF) at 96 h and by the number of individual cells moving across a filter within 5 h. In control conditions (1% calf serum) adherent fibroblasts moved from the starting line by approximately 700 microns. The addition of SP (10(-11)-10(-7) M) increased HF mobilisation in a concentration-dependent manner, with maximal activity at 10(-8) M (50% increase in migration over control). Migration of individual HF in suspension was also promoted by SP in a concentration-dependent manner, with an EC50 of 2.2 x 10(-9) M. The response produced by the maximally effective concentration of SP was equal to 65 and 90% of the effect elicited by 100 ng/ml Platelet-Derived Growth Factor A/B (PDGF A/B) on adherent and individual cells respectively. The synthetic NK1 receptor agonist [Sar9]SP-sulphone (10(-11)-10(-6) M) reproduced the SP effect. The NK2 and NK3 receptor agonists [beta Ala8]NKA(4-10) and [MePhe7]NKB were devoid of any effect. The effect of SP was antagonised by two selective antagonists of NK1 receptors, namely (+/-) CP 96,345 (10(-10)-10(-8) M) and FK 888 (10(-9)-10(-7) M), while the NK2 receptor antagonist MEN 10627 (10(-8)-10(-7) M) was not effective. Our data indicate that SP is a potent effector of fibroblast migration and the NK1 receptor is responsible for this effect. These observations further support the specific role of the NK1 receptor in mediating the trophic function of SP at the cutaneous level.

Analysis of Variance↗
PubMed1996

Effect of the non-peptide blocker (+/-) CP 96,345 on the cellular mechanism involved in the response to NK1 receptor stimulation in human skin fibroblasts.

The effect of the selective non-peptide antagonist for NK1 receptors (+/-)CP 96,345 on cellular transduction mechanisms elicited by the NK1 selective agonist [Sar9]-substance P-sulfone ([Sar9]-SP) was investigated in a stabilized culture of human skin fibroblasts (HF) and compared to the effects of two peptide antagonists, FK 888 and GR 82, 334. The exposure of the cells to [Sar9]-SP (100 nM) produced an early increase in inositol 1,4,5-trisphosphate (IP3) level, which peaked after 6 s, and a later rise in cellular inositol 1-phosphate (IP1) content which reached the maximum level in 15 min. The cAMP level was not significantly modified. The increase in IP1 was greatly reduced, at approximately the same extent by the 10 min pretreatment with a concentration of (+/-)CP 96,345 (100 nM) 10 times smaller than that of FK 888 and GR 82,334 (1 microM). The cytosolic Ca2+ mobilization in response to the NK1 agonist was monitored both by spectrofluorimetric and single-cell image analysis determinations on adherent cells loaded with the Ca(2+)-sensitive fluorescent indicators Fura-2/AM and Indo-1, respectively. [Sar9]-SP (100 nM) produced a rapid increase in the intracellular Ca2+ level in Fura-2/AM loaded cells. Cytosolic Ca2+ mobilization, measured by single-cell image analysis, indicated a concentration-dependent increase in both the ratio and in the number of cells responding to [Sar9]-SP. Either the non-peptide or the peptide selective NK1 receptor antagonists inhibited the increase in Ca2+ level in both the assays. In the spectrofluorimetric experiments the antagonizing effects of (+/-)CP 96,345 (1-100 nM), FK 888 (10 nM-1 microM) and GR 82,334 (10 nM-1 microM) were concentration-dependent. Moreover, the non-peptide antagonist was more potent than the two peptide antagonists, producing an 82.5% inhibition of Ca2+ mobilization at a concentration (10 nM) at which FK 888 and GR 82,334 decreased the response by only 62.3 and 60%, respectively. Stimulation of phosphatidylinositol turnover and calcium mobilization were also induced by 10 nM bradykinin; these effects were influenced neither by the previous administration of the NK1 receptor agonist nor by the three antagonists tested. These results demonstrate that the cellular transduction mechanisms induced in human skin fibroblasts by NK1 receptor stimulation are specifically and effectively antagonized by (+/-)CP 96,345, and that this non-peptide antagonist is more potent than the two peptide antagonists tested.

Biphenyl Compounds↗
PubMed1996

Thapsigargin inhibits the response to acetylcholine and substance P but does not interfere with the responses to endothelium-independent agents.

We investigated the influence of the Ca(2+)-ATPase inhibitor thapsigargin (TG) on the vasorelaxant response to different endothelium-dependent and endothelium-independent relaxing agents in an isolated thoracic aorta preparation of the rabbit, precontracted by norepinephrine (NE). Pretreatment with 100 microM L-arginine methyl ester (L-NAME) an inhibitor of nitric oxide (NO) synthesis, completely prevented acetylcholine (ACh)-induced relaxation; the inactive stereoisomer D-NAME did not modify the effect of ACh. The exposure of the preparations to 1 microM TG induced a slowly developing slight increase in the basal tension during 30-min contact. The same concentration of TG also slightly reduced the response to the subsequent administration of NE. The antagonist effect of TG on the ACh response was concentration dependent in the range between 0.1 and 10 microM. A 30-min pretreatment with 1 microM TG appeared to be sufficient to induce a consistent antagonism of the ACh (0.01-10 microM) concentration-relaxant effect curve, since an increase to 60 min did not produce a further significant increment in the degree of the antagonist effect. The concentration-dependent relaxation induced by substance P (SP 0.1-3 nM) was also significantly antagonized by 1 microM TG. The effect of the calcium ionophore A23187 (0.01-1 microM) was reduced by the Ca(2+)-ATPase inhibitor only at the higher concentrations tested (0.3-1 microM). However, a 30-min contact time with 1 microM TG was completely ineffective in antagonizing the concentration-relaxant response curves to the two nitrovasodilators sodium nitroprusside (SNP 0.1-100 microM) and nitroglycerin (NTG 1-300 nM) and to the cyclic GMP analogue 8-Bromo-cyclic GMP (3-100 microM). The effects of the beta-adrenoceptor agonist isoprenaline (ISO 0.1-10 microM) and of the direct adenylate cyclase activator forskolin (FK 0.01-10 microM) were also completely unaffected by 1 microM TG. These results demonstrate that TG affects the response to agents that induce an endothelium-dependent relaxation through receptor-dependent calcium mobilization. However, they do not support the hypothesis that sarcoplasmic pump activity is essential for the development of a vasorelaxant response to endothelium-independent agents.

Acetylcholine↗
PubMed1996

The effect of linomide on the migration and the proliferation of capillary endothelial cells elicited by vascular endothelial growth factor.

In order to assess the mechanism of action of the quinoline-3-carboxyamide linomide as an antiangiogenic drug, the effect of linomide was studied in vitro on postcapillary endothelial cells exposed to vascular endothelial growth factor (VEGF). Linomide did not block the spontaneous replication of endothelial cells, but significantly suppressed endothelial cell growth and migration elicited by VEGF. It is concluded that linomide appears to be an effective tool to inhibit VEGF-dependent angiogenesis.

Capillaries↗
PubMed1996

Nitric oxide mediates mitogenic effect of VEGF on coronary venular endothelium.

Vascular endothelial growth factor (VEGF) is a secreted protein that is a specific growth factor for endothelial cells. We have recently demonstrated that nitric oxide (NO) donors and vasoactive peptides promoting NO-mediated vasorelaxation induce angiogenesis in vivo as well as endothelial cell growth and motility in vitro; in contrast, inhibitors of NO synthase suppress angiogenesis. In this study we investigated the role of NO in mediating the mitogenic effect of VEGF on cultured microvascular endothelium isolated from coronary postcapillary venules. VEGF induced a dose-dependent increase in cell proliferation and DNA synthesis. The role of NO was determined by monitoring proliferation or guanosine 3',5'-cyclic monophosphate (cGMP) levels in the presence and absence of NO synthase blockers. The proliferative effect evoked by VEGF was reduced by pretreatment of the cells with NO synthase inhibitors. Exposure of the cells to VEGF induced a significant increment in cGMP levels. This effect was potentiated by superoxide dismutase addition and was abolished by NO synthase inhibitors. VEGF stimulates proliferation of postcapillary endothelial cells through the production of NO and cGMP accumulation.

Cell Line↗
PubMed1996

Basic fibroblast growth factor overexpression in endothelial cells: an autocrine mechanism for angiogenesis and angioproliferative diseases.

Basic fibroblast growth factor (bFGF) is expressed in vascular endothelium during tumor neovascularization and angioproliferative diseases. The ultimate significance of this observation is poorly understood. We have investigated the biological consequences of endothelial cell activation by endogenous bFGF in a mouse aortic endothelial cell line stably transfected with a retroviral expression vector harboring a human bFGF cDNA. Selected clones expressing M(r) 24,000, M(r) 22,000, and/or M(r) 18,000 bFGF isoforms were characterized by a transformed morphology and an increased saturation density. bFGF transfectants showed invasive behavior and sprouting activity in three-dimensional fibrin gels and formed a complex network of branching cord-like structures connecting foci of infiltrating cells when seeded on laminin-rich basement membrane matrix (Matrigel). The invasive and morphogenetic behavior was prevented by anti-bFGF antibody, revealing the autocrine modality of the process. The biological consequences of this autocrine activation were investigated in vivo. bFGF-transfected cells gave rise to highly vascularized lesions resembling Kaposi's sarcoma when injected in nude mice and induced angiogenesis in avascular rabbit cornea. When injected into the allantoic sac of the chick embryo, they caused an increase in vascular density and formation of hemangiomas in the chorioallantoic membrane. In conclusion, bFGF-overexpressing endothelial cells acquired an angiogenic phenotype and recruit quiescent endothelium originating angioproliferative lesions in vivo. These findings demonstrate that bFGF overexpression exerts an autocrine role for endothelial cells and support the notion that tumor neovascularization and angioproliferative diseases can be triggered by stimuli that induce vascular endothelium to produce its own autocrine factor(s).

3T3 Cells↗
PubMed1995

Growth advantage and vascularization induced by basic fibroblast growth factor overexpression in endometrial HEC-1-B cells: an export-dependent mechanism of action.

The human endometrial adenocarcinoma HEC-1-B cell line was transfected with an expression vector harboring the human basic fibroblast growth factor (bFGF) cDNA under the control of the human beta-actin gene promoter. Stable transfectants were obtained in which a constitutive, limited overexpression of M(r) 24,000, 22,000, and 18,000 bFGF isoforms was observed. When transfectants were screened for the capacity to release the growth factor, significant amounts of bFGF were present in the conditioned medium and extracellular matrix of the bFGF-B9 clone but not of the bFGF-A8 clone, even though both cell lines produced similar levels of intracellular bFGF. When compared to parental cells, bFGF-B9 cells showed down-regulation of tyrosine kinase fibroblast growth factor receptors along with up-regulation of urokinase-type plasminogen activator expression which was abolished by incubation of the cell cultures with neutralizing anti-bFGF antibody. In vivo, bFGF-B9 cells formed highly vascularized tumors growing faster than parental cells when injected s.c. in nude mice. Also, they were more potent than nontransfected cells in inducing an angiogenic response in the rabbit cornea assay. In contrast, the bFGF-A8 cell phenotype was indistinguishable from parental cells both in vitro and in vivo. In conclusion, clonal differences exist within the HEC-1-B cell line in the capacity to release bFGF. bFGF export by human endometrial adenocarcinoma cells results in autocrine and paracrine effects that confer a growth advantage in vivo associated with increased neovascularization.

Adenocarcinoma, Papillary↗
PubMed1995

Calcitonin gene-related peptide selectively increases cAMP levels in the guinea-pig ureter.

Calcitonin gene-related peptide (CGRP, 0.1 microM) and forskolin (10 microM) both produced a time-dependent accumulation of cAMP in homogenates of the guinea-pig ureter, while cromakalim (3 microM) was ineffective. Neither agent did increase the cGMP levels. cAMP accumulation induced by CGRP or forskolin was unchanged by glibenclamide (1 microM). In sucrose gap, the application of forskolin (1-10 microM for 15 s) hyperpolarized the smooth muscle membrane and its effect was greatly enhanced when tested in a low-K+ medium (extracellular K+ reduced from 5.9 to 1.2 mM). The hyperpolarization produced by 10 microM forskolin was reduced and abolished by 1 and 10 microM glibenclamide, respectively, in both normal and low-K+ medium. The present findings demonstrate that CGRP determines a selective cAMP accumulation in the guinea-pig ureter and suggest that elevation of cAMP may be involved in the opening of glibenclamide-sensitive K+ channels in the ureter smooth muscle.

Animals↗
PubMed1995

Enhancement of tumor growth and vascular density by transfection of vascular endothelial cell growth factor into MCF-7 human breast carcinoma cells.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a secreted endothelial-specific growth factor that is angiogenic in vivo. It is commonly expressed in a range of carcinomas. PURPOSE: The study was designed to investigate the effect of constitutive expression of VEGF on tumor formation by estrogen-dependent human MCF-7 breast carcinoma cells. METHODS: A full-length complementary DNA encoding the shortest isoform of VEGF (VEGF121) was stably transfected into MCF-7 cells. Transfected clones were screened for VEGF121 messenger RNA (mRNA) expression by ribonuclease protection analysis and for secretion of VEGF121 protein by Western blot analysis. Secretion of biologically active VEGF121 by transfectants was confirmed by 1) a competitive radioreceptor-binding assay, 2) stimulation of the growth of microvascular endothelial cells in vitro, and 3) potent angiogenic activity in the rabbit corneal assay. Tumor models were then established by subcutaneously implanting wild-type or VEGF121-transfected MCF-7 cells, together with either mouse BALB/3T3 clone A31 fibroblasts or human MDA-435S breast carcinoma cells, into ovariectomized nude mice either with or without a separately implanted slow-release estrogen pellet. Tumor vascularity was quantitatively assessed by capillary vessel counting after staining with the pan-endothelial marker CD31. RESULTS: Stable VEGF121-overexpressing MCF-7 cells were isolated and designated V12 cells. When implanted into the rabbit cornea, V12 cells elicited a strong directional outgrowth of capillaries. The growth rate of V12 cells in vitro was indistinguishable from that of MCF-7 wild-type cells. V12 cells formed faster growing tumors than did wild-type cells (P < .01) when xenografted subcutaneously into nude mice with either 3T3 fibroblasts or MDA-435S cells. Tumors formed from V12 cells were more vascular (P < .01) and showed a heterogeneous distribution of vessels when compared with the homogeneous distribution seen in tumors formed from wild-type cells. VEGF121 overexpression had no effect on hormone dependence or tamoxifen sensitivity of tumor formation by MCF-7 cells in mice. No macroscopic evidence for metastasis from subcutaneous implants was obtained. CONCLUSIONS: VEGF121 expression by breast carcinoma cells confers a growth advantage in vivo but not in vitro. Tumors formed by V12 transfectants were more vascular than those formed by wild-type MCF-7 cells, and we surmise that the growth advantage arises from increased tumor vascularization induced by VEGF121. IMPLICATIONS: Tumor formation by V12 cells could provide a useful model for the assessment of anti-angiogenic drugs.

3T3 Cells↗
PubMed1995

Proliferation and migration of endothelial cells is promoted by endothelins via activation of ETB receptors.

The growth and migration of endothelial cells are the prerequisites for vascular remodeling. The effects of endothelin (ET)-1 and -3 (ET-1, ET-3) on the proliferation and migration of endothelial cells isolated from bovine adrenal capillaries (BACE) and human umbilical veins (HUVEC) have been investigated. Cell proliferation (measured as DNA synthesis and as total cell number) and migration were significantly increased by ET-1 and ET-3. Dose-dependent proliferation was produced by ET-1 and ET-3 in both cell lines, with maximal effects at 0.1 nM concentration. ET-1 and ET-3 also stimulated BACE and HUVEC mobilization in a dose-dependent manner. The maximal responses were obtained at 10 nM concentration in both BACE and HUVEC. The full agonist for the ETB receptor, ET-(16--21), was able to reproduce the effects of ET on proliferation and migration of both cell lines. Modification of ET-(16--21) at Leu17 and Ile19 and amidation of the COOH-terminal were accompanied by loss of activity. The ETB-receptor antagonist IRL-1038 blocked the migration induced by ET-3 and ET-(16--21), whereas the ETA-receptor antagonist BQ-123 was not effective. We conclude that ETs, by favoring endothelial cell growth and mobilization, can contribute to neovascularization through an autocrine mechanism that requires ETB-receptor activation.

Adrenal Glands↗