Adult Bovine Aortic Endothelial Cells Research Articles

Death receptor 3 mediates TNFSF15- and TNFα-induced endothelial cell apoptosis

Tumor necrosis factor superfamily 15 (TNFSF15) suppresses angiogenesis by specifically inducing apoptosis in proliferating endothelial cells. Death receptor 3 (DR3), a member of the TNF receptor superfamily (TNFRSF25), has been identified as a receptor for TNFSF15 to activate T cells. It is unclear, however, whether DR3 mediates TNFSF15 activity on endothelial cells. Here we show that siRNA-mediated knockdown of DR3 in an in vivo Matrigel angiogenesis assay, or in adult bovine aortic endothelial (ABAE) cell cultures, leads to resistance of endothelial cells to TNFSF15-induced apoptosis. Interestingly, DR3-depleted cells also exhibited markedly diminished responsiveness to TNFα cytotoxicity, even though DR3 is not a receptor for TNFα. Treatment of the cells with either TNFSF15 siRNA or a TNFSF15-neutralizing antibody, 4-3H, also results in a significant inhibition of TNFα-induced apoptosis. Mechanistically, DR3 siRNA treatment gives rise to an increase of ERK1/2 MAPK activity, and up-regulation of the anti-apoptotic proteins c-FLIP and Bcl-2, thus strengthening apoptosis-resisting potential in the cells. These findings indicate that DR3 mediates TNFSF15-induced endothelial cell apoptosis, and that up-regulation of TNFSF15 expression stimulated by TNFα is partly but significantly responsible for TNFα-induced apoptosis in endothelial cells.

Effects of sulfated polysaccharide extracted from Prunella vulgaris on endothelial cells

Sulfated polysaccharide extracted from Prunella vulgaris, a commonly used traditional Chinese herb, possesses anti-tumor effect. But its underlying mechanism is unclear. The binding reaction of bFGF – P. vulgaris sulfated polysaccharide (PVSP) and bFGF - heparan were characterized by surface plasmon resonance assay. The competitive binding between bFGF - PVSP and bFGF - heparan sulfate were determined by solid phase combined assay. PVSP was capable of binding to bFGF in a dose - dependent manner. Moreover, PVSP could competitively inhibit the binding of heparan sulfate to the cell binding domain of bFGF in a dose - dependent manner. PVSP significantly inhibited the proliferation of ABAE cells in a dose - dependent and time - dependent manner. The percentage of apoptosis in adult bovine aortic endothelial cells showed significant difference between PVSP - treated cells and control cells. PVSP down regulated adult bovine aortic endothelial cell migration in a dose - dependent manner. Therefore, PVSP could ini¬‚uence the proliferation, apoptosis and migration of endothelial cells, which can be ascribed to the competitive ability of PVSP to inhibiting the binding of bFGF - heparan sulfate. Key words: Angiogenesis, endothelial cell, Prunella vulgaris, sulfated polysaccharide.

Antitumor and angiostatic peptides from frog skin secretions

The discovery of new molecules with potential antitumor activity continues to be of great importance in cancer research. In this respect, natural antimicrobial peptides isolated from various animal species including humans and amphibians have been found to be of particular interest. Here, we report the presence of two anti-proliferative peptides active against cancer cells in the skin secretions of the South American tree frog, Phyllomedusa bicolor. The crude skin exudate was fractioned by size exclusion gel followed by reverse-phase HPLC chromatography. After these two purification steps, we identified two fractions that exhibited anti-proliferative activity. Sequence analysis indicated that this activity was due to two antimicrobial α-helical cationic peptides of the dermaseptin family (dermaseptins B2 and B3). This result was confirmed using synthetic dermaseptins. When tested in vitro, synthetic B2 and B3 dermaseptins inhibited the proliferation of the human prostatic adenocarcinoma PC-3 cell line by more than 90%, with an EC(50) of around 2-3μM. No effect was observed on the growth of the NIH-3T3 non-tumor mouse cell line with Drs B2, whereas a slight inhibiting effect was observed with Drs B3 at high dose. In addition, the two fractions obtained after size exclusion chromatography also inhibited PC-3 cell colony formation in soft agar. Interestingly, inhibition of the proliferation and differentiation of activated adult bovine aortic endothelial cells was observed in cells treated with these two fractions. Dermaseptins B2 and B3 could, therefore, represent interesting new pharmacological molecules with antitumor and angiostatic properties for the development of a new class of anticancer drugs.

Abstract B41: Antitumoral and angiostatic activities in skin secretion of frog Phyllomedusa bicolor

Abstract The skin secretions of neotropical and South American frogs contains large amounts of a wide range of biological active peptides. Commonly studied are small peptides with antimicrobial activities as the Dermaseptin family. These peptides constitute a primitive immune defence mechanism and are able to disrupted the membranes of microbes and, subsequently, to inhibit their growth leading to cell death. Some of these antimicrobial peptides also present an antitumoral activity whereby they use a similar disrupting mechanism on the plasma membrane of the tumoral cells [1]. Therefore, intense research is now performed on the secretions from amphibian skin to discover new pharmacological agents, especially useful for drug-based cancer treatments. In this study we have postulated that the skin secretions from the South American frog Phyllomedusa bicolor contain such molecules and we reported antitumoral and angiostatic activities from a crude extract of these secretions [2]. After a two steps chromatography procedure, we have identified one of the bioactive compounds in this crude extract as Dermaseptin B2 (Drs B2) [3]. Drs B2 is a well known antimicrobial peptide which is 33-amino acid residues long. This natural α-helical peptide consist of a cationic NH2-terminal part (residues 1 to 23) predicted to form an amphipathic α-helix that is followed by a hydrophobic tail (residues 24 to 33). A synthetic Drs B2 peptide was prepared and tested for its antitumoral and angiostatic activities. Results obtained with this synthetic molecule were equal to those obtained by testing the crude extract in vitro. Thus, Drs B2 inhibited the growth of different human tumoral cell lines like the prostatic adenocarcinoma cell line PC3 and the mammary carcinoma cell line MDA-MB231 when cultured on plastic or in soft agar with an EC50 of 1–2 μM. Drs B2 was also able to inhibit non adherent human tumoral cells like the Raji and LB-EBV lymphoma cell lines with the same efficiency. It is noteworthy that Drs B2 showed an inhibitory effect on non tumoral cells like NIH-3T3 and primary mouse embryonic cells but only when concentrations higher than 10 μM where used. Furthermore, Drs B2 was evaluated for its effect on endothelial cells growth and was able to inhibit to growth of the adult bovine aortic endothelial cells (ABAE) in vitro. Moreover, Drs B2 could also block the capillary network formation induced by FGF-2 of these cells when cultured on collagen in a Montesano model. In conclusion, Drs B2 could represent a new interesting pharmacological leader molecule against the proliferation of human tumoral cells that now need to be evaluated on different cancer cell types in vitro but also in vivo in animal models. Besides that, also the mechanism of action of Drs B2 on tumoral cells has to be clear before further pharmacological development. Citation Information: Clin Cancer Res 2010;16(7 Suppl):B41

Sensitization of endothelial cells to VEGI-induced apoptosis by inhibiting the NF-κB pathway

Vascular endothelial growth inhibitor (VEGI) is an endogenous inhibitor of endothelial cell growth and a promising candidate for cancer therapy. VEGI is able to inhibit tumor growth by specifically targeting the tumor neovasculature. Increasing the anti-angiogenic potential of this cytokine is of great interest for its therapeutic potential. NF-kappaB is known to have an integral role in TNF superfamily signaling, acting as a pro-survival factor. A role of VEGI-induced NF-kappaB activation in endothelial cells has yet to be described. Here we show that suppression of the NF-kappaB pathway can increase the apoptotic potential of VEGI. We used siRNA to deplete NF-kappaB or its activator IKK2 from adult bovine aortic endothelial cells. The siRNA treatments diminished VEGI-induced NF-kappaB activation, evidenced from a reduced extent of NF-kappaB nuclear translocation and diminished expression of NF-kappaB-target genes such as interleukins-6 and -1beta. The siRNA-treated endothelial cells when exposed to VEGI exhibited a marked decrease in cell viability and a significant increase in apoptosis. These results confirm that VEGI utilizes NF-kappaB as a pro-survival role factor in endothelial cells. We then examined whether a combination of VEGI with NF-kappaB inhibitors would constitute a more potential therapeutic regiment. We found that in the presence of the NF-kappaB inhibitors curcumin or BMS-345541 there was a marked increase in the apoptotic potential of VEGI on endothelial cells. These findings indicate that a combination therapy using VEGI and NF-kappaB inhibitors could be a potent approach for cancer treatment.

The Antiangiogenic Factor, 16-kDa Human Prolactin, Induces Endothelial Cell Cycle Arrest by Acting at Both the G0–G1 and the G2–M Phases

The 16-kDa N-terminal fragment of human prolactin (16K hPRL) is a potent antiangiogenic factor that has been shown to prevent tumor growth in a xenograph mouse model. In this paper we first demonstrate that 16K hPRL inhibits serum-induced DNA synthesis in adult bovine aortic endothelial cells. This inhibition is associated with cell cycle arrest at both the G(0)-G(1) and the G(2)-M phase. Western blot analysis revealed that 16K hPRL strongly decreases levels of cyclin D1 and cyclin B1, but not cyclin E. The effect on cyclin D1 is at least partially transcriptional, because treatment with 16K hPRL both reduces the cyclin D1 mRNA level and down-regulates cyclin D1 promoter activity. This regulation may be due to inhibition of the MAPK pathway, but it is independent of the glycogen synthase kinase-3beta pathway. Lastly, 16K hPRL induces the expression of negative cell cycle regulators, the cyclin-dependent kinase inhibitors p21(cip1) and p27(kip1). In summary, 16K hPRL inhibits serum-induced proliferation of endothelial cells through combined effects on positive and negative regulators of cell cycle progression.

Bioactivity of Lignans from Taxus baccata

Three lignan derivatives, (-)-taxiresinol (1), (-)-3'-demethylisolariciresinol-9'-hydroxyisopropylether (2) and (-)-3-demethylisolariciresinol (3), previously isolated from the heart-wood of Taxus baccata L. (Taxaceae) were investigated for cytotoxicity against the Oncology Cell Line Panel (breast, colon, ovary, prostate, lung and a normal adult bovine aortic endothelial cell line) as well as for antimicrobial activities. Besides, a chloroform-soluble portion of the ethanol extract from the heartwood of T. baccata was also tested for antimicrobial activities. Compounds 1 - 3 did not demonstrate much cytotoxic potency according to the reference drug etoposide. With the exception of compound 2, the other two lignans (1 and 3) and the chloroform extract were shown to possess antifungal activity, whereas only the chloroform extract exhibited antibacterial activity against Pseudomonas aeruginosa.

Submerged Cultured Mycelium Extracts of Higher Basidiomycetes Mushrooms Selectively Inhibit Proliferation and Induce Differentiation of K562 Human Chronic Myelogenous Leukemia Cells

Human Chronic Myelogenous Leukemia (CML) is a malignancy of pluripotent hematopoietic cells characterized by distinctive cytogenetic abnormality known as the Philadelphia (Ph) chromosome, which resulted in the creation of a p210 Bcr-Abl fusion protein with increased tyrosine kinase activity. Forty-two species of Higher Basidiomycetes mushrooms were cultivated as pure cultures in submerged conditions, and dry mycelium were used to prepare 168 different crude extracts. The crude extracts were used to evaluate anti-proliferative activity against a number of cancer cell lines, including K562 (Human Chronic myelogenous leukemia cell line), Jurkat (human T lymphoblast cells), HT29 (human colon adenocarcinoma cells), MH3924A (rat Morris hepatoma), and ABAE (adult bovine aortic endothelial cells) using XTT proliferation assay. Forty-four different crude extracts were selected with anti-proliferative effect against K562 cells and eight mycelium extracts were K562selective compared with MH3924A, HT29, ABAE, and Jurkat cells. Growth inhibition against K562 ranged from 51% to 78% compared with solvent-treated samples. Most crude extracts exhibited a complete or partial cytostatic effect against K562 cells. The anti-proliferative effect observed by the selected crude extracts was attributed to the induction of apoptosis pathway as determined by Apostain ELISA assay and by monitoring PARP cleavage. Interestingly, crude extract MH428 was the most active extract in inducing apoptosis of K562 cells. In addition, expression levels of p210 Bcr-Abl were affected by the presence of the selected crude extracts. Our data revealed a significant inhibition of p210 Bcr-Abl expression by MH428 extract, a moderate effect by MH17, and minor changes by the other extracts. Furthermore, mycelium crude extracts were active in inducing erythroid differentiation in K562 cells. Crude extracts Meth178, MH17, and MH428 show significant ability to induce hemoglobin production in K562 cells as indicative of erythroid differentiation. The results obtained support the potential use of the crude mycelium extracts for the treatment of CML and beta-globin disorders.

Venous shear stress enhances platelet mediated staphylococcal adhesion to artificial and damaged biological surfaces

We investigated the role of blood components in the adhesion of staphylococci to biological and artificial surfaces under well-defined flow conditions by using the Cone and Plate(let) Analyzer. An enzyme-linked immunosorbent assay-like binding assay with biotinylated bacteria determined the extent of bacterial adhesion to subendothelial extracellular matrix (ECM), polystyrene (PS) and adult bovine aortic endothelial (ABAE) cell monolayer. The presence of adsorbed plasma proteins on PS and ECM did not increase and in some cases reduced staphylococcal adhesion under flow conditions (200 s −1). However, their presence on ABAE cells increased bacterial adhesion but to a level still lower than the adhesion to PS and ECM. In contrast, adhered platelets significantly increased staphylococcal adhesion to both PS and ECM, but did not affect the adhesion to ABAE cells. Furthermore, bacterial adhesion to the platelets coated ECM and PS under flow conditions (200 s −1) was increased by 1.4 to 2.6-fold compare to static conditions. The platelet-enhanced bacterial adhesion was markedly inhibited by blockade of the platelet GPIb receptor. In conclusion, staphylococcal extensive adhesion to ECM and PS surfaces is increased by venous flow and mediated by surface adhered activated platelets via a GPIb dependent mechanism. On the other hand, ABAE cells demonstrated limited bacterial adhesion that is mediated by adsorbed plasma proteins. Our results suggest that under physiological venous flow conditions the intact vessel wall is less prone for bacterial adhesion than damaged vessel wall.

Identification of Ribosome-binding Protein p34 as an Intracellular Protein That Binds Acidic Fibroblast Growth Factor

With the aim of identifying new intracellular binding partners for acidic fibroblast growth factor (aFGF), proteins from U2OS human osteosarcoma cells were adsorbed to immobilized aFGF. One of the adsorbed proteins is a member of the leucine-rich repeat protein family termed ribosome-binding protein p34 (p34). This protein has previously been localized to endoplasmic reticulum membranes and is thought to span the membrane with the N terminus on the cytosolic side. Confocal microscopy of cells transfected with Myc-p34 confirmed the endoplasmic reticulum localization, and Northern blotting determined p34 mRNA to be present in a multitude of different tissues. Cross-linking experiments indicated that the protein is present in the cell as a dimer. In vitro translated p34 was found to interact with maltose-binding protein-aFGF through its cytosolic coiled-coil domain. The interaction between aFGF and p34 was further characterized by surface plasmon resonance, giving a K(D) of 1.4 +/- 0.3 microm. Even though p34 interacted with mitogenic aFGF, it bound poorly to the non-mitogenic aFGF(K132E) mutant, indicating a possible involvement of p34 in intracellular signaling by aFGF.

Fibroblast Growth Factor-2 Antagonist Activity and Angiostatic Capacity of Sulfated Escherichia coli K5 Polysaccharide Derivatives

The angiogenic basic fibroblast growth factor (FGF2) interacts with tyrosine kinase receptors (FGFRs) and heparan sulfate proteoglycans (HSPGs) in endothelial cells. Here, we report the FGF2 antagonist and antiangiogenic activity of novel sulfated derivatives of the Escherichia coli K5 polysaccharide. K5 polysaccharide was chemically sulfated in N- and/or O-position after N-deacetylation. O-Sulfated and N,O-sulfated K5 derivatives with a low degree and a high degree of sulfation compete with heparin for binding to 125I-FGF2 with different potency. Accordingly, they abrogate the formation of the HSPG.FGF2.FGFR ternary complex, as evidenced by their capacity to prevent FGF2-mediated cell-cell attachment of FGFR1-overexpressing HSPG-deficient Chinese hamster ovary (CHO) cells to wild-type CHO cells. They also inhibited 125I-FGF2 binding to FGFR1-overexpressing HSPG-bearing CHO cells and adult bovine aortic endothelial cells. K5 derivatives also inhibited FGF2-mediated cell proliferation in endothelial GM 7373 cells and in human umbilical vein endothelial (HUVE) cells. In all these assays, the N-sulfated K5 derivative and unmodified K5 were poorly effective. Also, highly O-sulfated and N,O-sulfated K5 derivatives prevented the sprouting of FGF2-transfected endothelial FGF2-T-MAE cells in fibrin gel and spontaneous angiogenesis in vitro on Matrigel of FGF2-T-MAE and HUVE cells. Finally, the highly N,O-sulfated K5 derivative exerted a potent antiangiogenic activity on the chick embryo chorioallantoic membrane. These data demonstrate the possibility of generating FGF2 antagonists endowed with antiangiogenic activity by specific chemical sulfation of bacterial K5 polysaccharide. In particular, the highly N,O-sulfated K5 derivative may provide the basis for the design of novel angiostatic compounds.

Lysophosphatidic acid and sphingosine 1-phosphate stimulate endothelial cell wound healing.

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are potent lipid growth factors with similar abilities to stimulate cytoskeleton-based cellular functions. Their effects are mediated by a subfamily of G protein-coupled receptors (GPCRs) encoded by endothelial differentiation genes (edgs). We hypothesize that large quantities of LPA and S1P generated by activated platelets may influence endothelial cell functions. Using an in vitro wound healing assay, we observed that LPA and S1P stimulated closure of wounded monolayers of human umbilical vein endothelial cells and adult bovine aortic endothelial cells, which express LPA receptor Edg2, and S1P receptors Edg1 and Edg3. The two major components of wound healing, cell migration and proliferation, were stimulated individually by both lipids. LPA and S1P also stimulated intracellular Ca(2+) mobilization and mitogen-activated protein kinase (MAPK) phosphorylation. Pertussis toxin partially blocked the effects of both lipids on endothelial cell migration, MAPK phosphorylation, and Ca(2+) mobilization, implicating G(i)/(o)-coupled Edg receptor signaling in endothelial cells. LPA and S1P did not cross-desensitize each other in Ca(2+) responses, suggesting involvement of distinct receptors. Thus LPA and S1P affect endothelial cell functions through signaling pathways activated by distinct GPCRs and may contribute to the healing of wounded vasculatures.

Angiopoietin-1 and Its Receptor Tie-2 Participate in the Regulation of Capillary-like Tubule Formation and Survival of Endothelial Cells

Angiopoietin-1 (Ang-1) and its receptor Tie-2, a trans-membrane tyrosine kinase uniquely expressed by endothelial cells, are shown by null mutation studies to be essential to developmental angiogenesis. The phenotypic abnormalities in these knockout animals suggest that Tie-2 signaling is necessary for the maintenance and expansion of the primitive capillary network. We present in vitro evidence indicating that the Ang-1/Tie-2 system participates in the regulation of capillary tubule formation and is necessary for the survival of confluent endothelial cells. Although recombinant Ang-1, which induces Tie-2 phosphorylation, has no effect on the proliferation of endothelial cells, treatment of confluent adult bovine aortic endothelial cells (ABAE) cells grown on collagen gels with Ang-1 (100 ng/ml) causes the cells to migrate into the collagen gel and form capillary-like tubules. The tubule-forming effect of Ang-1 is similar to the effect caused by FGF-2. A soluble form of the Tie-2 extracellular domain, in fivefold molar excess, blocks Ang-1-induced tubule formation. Specific elimination of Tie-2 protein expression in cultured ABAE cells as a result of transfection with an antisense oligonucleotide causes cell death in a dose-dependent manner (IC50 = 50 nM). The antisense treatment has no effect on cells that do not express Tie-2. Cells treated with antisense oligonucleotide show a sixfold increase in the rate of apoptosis as assessed by in situ end labeling of fragmented DNA. These findings are consistent with the view that Ang-1/Tie-2 signaling is essential for both angiogenesis and endothelial cell survival.

VEGI, a novel cytokine of the tumor necrosis factor family, is an angiogenesis inhibitor that suppresses the growth of colon carcinomas in vivo.

A novel member of the tumor necrosis factor (TNF) family has been identified from the human umbilical vein endothelial cell cDNA library, named vascular endothelial growth inhibitor (VEGI). The VEGI gene was mapped to human chromosome 9q32. The cDNA for VEGI encodes a protein of 174 amino acid residues with the characteristics of a type II transmembrane protein. Its amino acid sequence is 20-30% identical to other members of the TNF family. Unlike other members of the TNF family, VEGI is expressed predominantly in endothelial cells. Local production of a secreted form of VEGI via gene transfer caused complete suppression of the growth of MC-38 murine colon cancers in syngeneic C57BL/6 mice. Histological examination showed marked reduction of vascularization in MC-38 tumors that expressed soluble but not membrane-bound VEGI or were transfected with control vector. The conditioned media from soluble VEGI-expressing cells showed marked inhibitory effect on in vitro proliferation of adult bovine aortic endothelial cells. Our data suggest that VEGI is a novel angiogenesis inhibitor of the TNF family and functions in part by directly inhibiting endothelial cell proliferation. The results further suggest that VEGI maybe highly valuable toward angiogenesis-based cancer therapy.

Cell-surface ADP-ribosylation of fibroblast growth factor-2 by an arginine-specific ADP-ribosyltransferase

Basic fibroblast growth factor (FGF-2) appeared to be ADP-ribosylated on the surface of adult bovine aortic arch endothelial and human hepatoma cells. Further characterization of this reaction with cells expressing an arginine-specific, glycosylphosphatidylinositol-anchored, mono-ADP-ribosyltransferase demonstrated that FGF-2 is ADP-ribosylated on arginine. Incubation of transformed cells with FGF-2 and [adenylate-32P]nicotinamide-adenine dinucleotide (NAD) resulted in the rapid incorporation of [32P]ADP-ribose into FGF-2 in a time- and concentration-dependent manner, with labelling averaging 3 mol of ADP-ribose/mol of FGF-2. Excess ADP-ribose had no effect on these reactions, whereas excess NAD inhibited the ADP-ribosylation of FGF-2, consistent with an enzymic rather than a non-enzymic ADP-ribosylation reaction. Heparin also inhibited the ADP-ribosylation reaction, whereas a neutralizing polyclonal anti-peptide antibody had no effect. Furthermore, the addition of putative receptor binding domain peptide analogues of FGF-2 reduced the maximal ADP-ribosylation of FGF-2. These results identify the cell-surface ADP-ribosylation of FGF-2 as a potentially ubiquitous event.

Oxidized High-Density Lipoproteins Modulate Endothelin Secretion by Adult Bovine Aortic Endothelial Cells

High-density lipoprotein (HDL) cholesterol levels are well established as an inverse risk factor for atherosclerosis. This fact is probably related to the ability of HDL to induce cholesterol efflux from the vascular cell. It is also possible that HDL affects the production of different mediators implicated in the development of atheroslerosis. Endothelin is a vasconstricting mitogenic peptide involved in the development of atherosclerosis. We studied whether native HDL, oxidized HDL and tetranitromethane HDL modulate the endothelin secretion of cultured adult bovine aortic endothelial cells. We determined the effect of native HDL and modified HDLs (oxidized HDL and tetranitromethane HDL) on the secretion of endothelin by cultured adult bovine aortic endothelial cells. An endothelin radioimmunoassay system was used to quantify levels of immunoreactive endothelin in the cultured media. Native HDL, tetranitromethane HDL and oxidized HDL produced a highly significant stimulation of endothelin secretion (maximum 294% of control), even at low concentrations (10 and 20 micrograms/ml). Oxidized HDL2 and oxidized HDL3 produced a biphasic effect, with maximum secretion occurring with 100 micrograms/ml oxidized HDL3 (294% of control) and 50 micrograms/ml oxidized HDL2 (252% of control). The secretion of the peptide decreased with higher concentrations of oxidized HDL2 and oxidized HDL3. Because modified HDLs (oxidized HDL and tetranitromethane HDL) do not bind to the 'HDL receptor' to stimulate endothelin secretion, we propose that the stimulation of secretion is mediated by unspecific binding of the lipoprotein to the cell membrane. Nevertheless, oxidized HDL and tetranitromethane HDL may stimulate endothelin secretion via the scavenger-receptor pathway. Our results suggest that HDL and modified HDL participate in the regulation of vascular tone.

Oxidized high-density lipoproteins modulate endothelin secretion by adult bovine aortic endothelial cells

Oxidized high-density lipoproteins modulate endothelin secretion by adult bovine aortic endothelial cells

Oxidised LDL Modulates Endothelin Secretion by Adult Bovine Aortic Endothelial Cells

An increased level of low density lipoproreins (LDL) in the blood and an accumulation of oxidized-LDL (ox-LDL) in the subendothelium are well known factors of atherosclerosis. Endothelin (ET), a potent vasoconstrictor isolated from endothelial cells, is mitogenic for smooth muscle cells and may participate in atherogenesis by this process. In the present paper we study the effects of native LDL and ox-LDL on ET secretion by adult bovine aortic endothelial cells (ABAE). Native LDL stimulate ET secretion in a dose dependent manner between 25 and 200 μg/ml, while the effects of ox-LDL are complex. A low concentration (50 μg/ml) of highly ox-LDL induces ET secretion while a high concentration (100 μg/ml) does not induce the secretion and is cytotoxic. 100 μ/ml of slightly ox-LDL stimulates the secretion. Our data indicated that the LDL(B/E) receptor pathway is not involved in n-LDL induced ET secretion and are not conclusive on the role of the scavenger receptor pathway in ox-LDL induced ET secretion. Lysolec...

1,25-Dihydroxyvitamin d 3 potentiates the cytotoxic effect of TNF on human breast cancer cells

We studied the effect of 1,25-dihydroxyvitamin D 3 (1,25(OH) 2D 3) on the cytotoxic action of TNF on MCF-7 human breast cancer cells and on adult bovine aortic endothelial cells. 1,25(OH) 2D 3 increased the effect of TNF on MCF-7 cells but not on endothelial cells over a wide TNF concentration range. At a suboptimal concentration (1 ng/ml) the potentiation was twofold. The effect of 1,25(OH) 2D 3 was specific, dose-dependent and apparent at a physiological concentration (0.1 nM) of the hormone. The potentiating effect of 1,25(OH) 2D 3 on TNF action was abolished by cycloheximide indicating that their interaction requires protein synthesis. Addition of 1,25(OH) 2D 3 13 h after TNF in a 28-h assay was sufficient to induce its full potentiating effect indicating that the hormone modulates a late event in the cytokine's action. These data suggest that some of the in vivo antitumor effects of 1,25(OH) 2D 3 may be due to an increase in the anti-cancer activity of the immune system.

Ligands of the Antiestrogen Binding Site Block Endothelial Cell Proliferation Reversibly

Benzylphenoxyethanamine derivatives are known to display antiproliferative activities on tumor cell lines consistently with their binding affinity to the microsomal antiestrogen binding site. In the present study we show that pyrrolidinobenzylphenoxyethanamine, a new efficient compound of this series, exhibits reversible effects on exponentially growing adult bovine aortic endothelial cells inducing (1) lamellated cytoplasmic inclusions, (2) cell proliferation inhibition, (3) dose-dependent transition delay of cells in the G0-G1 phase of the cell cycle. Complete reversal of these effects is achieved only by withdrawing the drug from the medium. The ultrastructural cellular modifications disappeared, and flow cytometry and thymidine incorporation analysis showed the effect on degree of synchronization of this one-step methodology.