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Abstract
Peroxisome proliferator-activated receptor {gamma} (PPARgamma), the nuclear receptor that binds the insulin-sensitizing thiazolidinediones (TZDs), is prominently upregulated in intimal vascular smooth muscle cells (VSMC) after mechanical injury to the vessel wall. Several TZD PPARgamma ligands have been shown to inhibit neointima formation in both normal and insulin-resistant vasculature. The suppression of intimal hyperplasia by TZD PPARgamma ligands probably results from their activity to inhibit VSMC growth and promote apoptosis. TZDs prevent VSMC proliferation by blocking the activity of regulatory proteins, such as phosphorylation of the retinoblastoma protein (Rb). Rb functions as a G(1) gatekeeper by controlling S phase gene expression mediated by the E2F transcription factor. Consistent with their effect on Rb phosphorylation, PPARgamma ligands inhibit the mitogenic induction of minichromosome maintenance (MCM) proteins 6 and 7, two E2F-regulated S phase genes essential for DNA replication. PPARgamma ligands also induced apoptosis in VSMC, which correlated with a potent induction of GADD45, a gene implicated in controlling cell growth and survival. A constitutively active form of PPARgamma targeted the same cell cycle regulators as did PPARgamma ligands, consistent with a nuclear-receptor-dependent mechanism of action. This review will summarize mechanisms through which PPARgamma modulates VSMC proliferation and apoptosis suggesting that PPARgamma itself is a novel important regulator of cell cycle and apoptosis and may provide a new therapeutic approach to prevent restenosis.
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Affiliation(s)
- D Bruemmer
- Division of Endocrinology and Molecular Medicine, University of Kentucky College of Medicine, Lexington, KY, USA.
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2
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Pross C, Farooq MM, Lane JS, Angle N, Tomono CK, Xavier AE, Freischlag JA, Collins AE, Law RE, Gelabert HA. Rat and human aortic smooth muscle cells display differing migration and matrix metalloproteinase activities in response to dexamethasone. J Vasc Surg 2002; 35:1253-9. [PMID: 12042738 DOI: 10.1067/mva.2002.123332] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The steroid dexamethasone inhibits neointimal hyperplasia development in rats but not in humans. This study investigates the differential effects of dexamethasone on rat and human smooth muscle cell migration and matrix metalloproteinase (MMP) activity. METHODS Rat aortic smooth muscle cells were harvested from Sprague-Dawley rats. Human aortic smooth muscle cells were obtained from Clonetics. Boyden chamber migration assays were performed with chemoattractant (platelet-derived growth factor) and varying concentrations of dexamethasone (10(-9) to 10(-5) mol/L). Zymography of culture media was used to assess MMP activity, and Western blot analysis was used for quantification of MMP-2 and tissue inhibitor of MMP-2 (TIMP-2) secretion. RESULTS Dexamethasone inhibits rat aortic smooth muscle cell migration in a dose-dependent fashion. An increase in concentrations of dexamethasone does not effect human aortic smooth muscle cell migration. Rat aortic smooth muscle cell MMP-2 activity is inhibited with dexamethasone in a dose-dependent fashion, and human aortic smooth muscle cell MMP-2 activity is unchanged with dexamethasone. MMP-2 secretion is inhibited with dexamethasone in rat aortic smooth muscle cells but remains unaltered in human aortic smooth muscle cells. Dexamethasone increases rat aortic smooth muscle cell TIMP-2 secretion, and human aortic smooth muscle cell TIMP-2 secretion remains constant. CONCLUSION Dexamethasone inhibits rat aortic smooth muscle cell migration, MMP-2 activity, and MMP-2 secretion and increases TIMP-2 secretion. These effects are not observed in human aortic smooth muscle cells. These findings may explain why dexamethasone inhibits neointimal hyperplasia in animal models but is ineffective in humans. Inhibition of human smooth muscle cell migration in vitro may be useful in predicting the effectiveness of future therapeutic agents for treatment of neointimal hyperplasia in humans.
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Affiliation(s)
- C Pross
- Division of Vascular Surgery, Gonda (Goldschmied) Center for Vascular Surgery, University of California-Los Angeles Medical Center, UCLA School of Medicine, 200 Medical Plaza, Los Angeles, CA 90095, USA
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3
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Pross C, Farooq MM, Angle N, Lane JS, Cerveira JJ, Xavier AE, Freischlag JA, Law RE, Gelabert HA. Dexamethasone inhibits vascular smooth muscle cell migration via modulation of matrix metalloproteinase activity. J Surg Res 2002; 102:57-62. [PMID: 11795999 DOI: 10.1006/jsre.2001.6220] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Dexamethasone (DEX) has been shown to inhibit development of neointimal hyperplasia in rats. We hypothesize that DEX inhibits neointimal hyperplasia by altering matrix metalloproteinase (MMP) activity, resulting in inhibition of smooth muscle cell migration. METHODS Rat aortic smooth muscle cells (RASMC) were harvested and cultured for two to four passages. A migration assay was performed in a Boyden chamber with chemoattractant (platelet-derived growth factor) and varying concentrations of DEX (10(-9) to 10(-5) M). The number of migrated cells was counted under light microscopy. Zymography was performed on culture media to assess MMP activity, and Western blotting was performed to assay MMP and levels of tissue inhibitors of MMPs (TIMPs). RESULTS DEX progressively inhibited RASMC migration in a dose-dependent fashion. This effect was statistically significant for concentrations of 10(-7) to 10(-5) M (P < 0.0005). Zymography showed that DEX inhibits MMP-2 activity in a dose-dependent manner. Western blots indicated that total MMP-2 secretion was inhibited and that TIMP-2 secretion was increased by DEX. CONCLUSIONS DEX inhibits platelet-derived growth factor-induced migration of RASMCs and MMP-2 activity in vitro. Our data suggest that DEX suppresses MMP activity and secretion, resulting in the inhibition of smooth muscle cell migration. This may explain the mechanism by which DEX inhibits neointimal hyperplasia.
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Affiliation(s)
- C Pross
- Division of Vascular Surgery, University of California-Los Angeles Medical Center, Los Angeles, California 90096, USA
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4
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Wakino S, Kintscher U, Liu Z, Kim S, Yin F, Ohba M, Kuroki T, Schönthal AH, Hsueh WA, Law RE. Peroxisome proliferator-activated receptor gamma ligands inhibit mitogenic induction of p21(Cip1) by modulating the protein kinase Cdelta pathway in vascular smooth muscle cells. J Biol Chem 2001; 276:47650-7. [PMID: 11598137 DOI: 10.1074/jbc.m108719200] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The cyclin-dependent kinase inhibitor p21(Cip1) is up-regulated in response to mitogenic stimulation in various cells. PPARgamma ligands troglitazone (TRO, 10 microm) and rosiglitazone (RSG, 10 microm) attenuated the induction of p21(Cip1) protein by platelet-derived growth factor (PDGF) and insulin without affecting cognate mRNA levels in rat aortic smooth muscle cells (RASMC). The protein kinase Cdelta (PKCdelta) inhibitor rottlerin also blocked the induction of p21(Cip1) protein, whereas the conventional PKC isotype inhibitor Gö 6976 had no effect. Kinetic studies using the protein synthesis inhibitor cycloheximide showed that TRO, RSG, and rottlerin shortened the half-life of p21(Cip1) protein. TRO, RSG, and rottlerin inhibited PDGF-induced expression of p21(Cip1), but they did not affect insulin-induced expression of p21(Cip1). Both ligands inhibited PKCdelta enzymatic activity in PDGF-stimulated RASMC but not in insulin-stimulated cells. Adenovirus-mediated overexpression of PKCdelta rescued the down-regulation of p21(Cip1) expression both by TRO and RSG in PDGF-treated RASMC. These data suggested that the PKCdelta pathway plays a critical role in PDGF-induced expression of p21(Cip1) in RASMC and may be the potential target for PPARgamma ligand effects. Src kinase-dependent tyrosine phosphorylation of PKCdelta was decreased substantially by TRO and RSG. Tyrosine phosphorylation and activation of c-Src in response to PDGF were unaffected by either PPARgamma ligand. Protein-tyrosine-phosphatase inhibitors sodium orthovanadate and dephostatin prevented PPARgamma ligand effects on PKCdelta tyrosine phosphorylation and enzymatic activity. Both inhibitors also reversed PPARgamma ligand effects on p21(Cip1) expression in PDGF-treated RASMC. PPARgamma ligands enhanced protein-tyrosine-phosphatase activity in RASMC, which may be the mechanism for decreased PKCdelta tyrosine phosphorylation and activity. PPARgamma ligands regulate p21(Cip1) at a post-translational level by blocking PKCdelta signaling and accelerating p21(Cip1) turnover.
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MESH Headings
- Acetophenones/pharmacology
- Adenoviridae/genetics
- Animals
- Aorta, Thoracic/cytology
- Apoptosis
- Benzopyrans/pharmacology
- Blotting, Western
- Carbazoles/pharmacology
- Cell Division
- Cells, Cultured
- Chromans/pharmacology
- Cyclin-Dependent Kinase Inhibitor p21
- Cyclins/metabolism
- Cycloheximide/pharmacology
- Dose-Response Relationship, Drug
- Down-Regulation
- Enzyme Inhibitors/pharmacology
- Hydroquinones/pharmacology
- Indoles/pharmacology
- Insulin/metabolism
- Isoenzymes/metabolism
- Kinetics
- Ligands
- Mice
- Mitogens/pharmacology
- Models, Biological
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/enzymology
- Phosphorylation
- Platelet-Derived Growth Factor/pharmacology
- Precipitin Tests
- Protein Kinase C/metabolism
- Protein Kinase C-delta
- Protein Processing, Post-Translational
- Protein Synthesis Inhibitors/pharmacology
- Protein Tyrosine Phosphatases/antagonists & inhibitors
- RNA/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Cytoplasmic and Nuclear/metabolism
- Recombinant Proteins/metabolism
- Rosiglitazone
- Signal Transduction
- Thiazoles/pharmacology
- Thiazolidinediones
- Time Factors
- Transcription Factors/metabolism
- Troglitazone
- Tyrosine/metabolism
- Up-Regulation
- Vanadates/pharmacology
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Affiliation(s)
- S Wakino
- Division of Endocrinology, Diabetes, and Hypertension, School of Medicine, 142-8555 UCLA, 900 Veteran Ave., Los Angeles, CA 90095, USA
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5
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Goetze S, Kintscher U, Kim S, Meehan WP, Kaneshiro K, Collins AR, Fleck E, Hsueh WA, Law RE. Peroxisome proliferator-activated receptor-gamma ligands inhibit nuclear but not cytosolic extracellular signal-regulated kinase/mitogen-activated protein kinase-regulated steps in vascular smooth muscle cell migration. J Cardiovasc Pharmacol 2001; 38:909-21. [PMID: 11707695 DOI: 10.1097/00005344-200112000-00013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Vascular smooth muscle cell (VSMC) migration involves adhesion, locomotion, and invasion regulated by various signaling molecules, among which the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinases (MAPK) play a critical role. We have shown that the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligands troglitazone and rosiglitazone inhibit VSMC migration downstream of ERK MAPK. The purpose of the current study was to more specifically determine which step(s) in VSMC migration are targeted by inhibition of the ERK MAPK pathway or activation of PPAR-gamma. VSMC adhesion was not affected by the ERK MAPK pathway inhibitor PD98059 or PPAR-gamma ligands. Phosphorylation and activation of myosin light chain kinase (MLCK) play important roles in cell locomotion. Platelet-derived growth factor (PDGF)-induced MLCK phosphorylation (1.7-fold) was completely blocked by PD98059 at 30 microM (p < 0.05), but not by troglitazone or rosiglitazone. PDGF-directed migration (5.8-fold) was inhibited by PD98059 (-88% at 30 microM) and the MLCK inhibitor ML9 (0.1-1 microM, -84% at 1 microM) (all p < 0.05). The transcription factor Ets-1 mediates matrix metalloproteinase induction required for tissue invasion by VSMC. PDGF (20 ng/ml) stimulated an Ets-1 protein expression (14-fold at 60 min) in VSMC, which was inhibited by PD98059 (-72% at 30 microM), troglitazone (-69% at 20 microM), and rosiglitazone (-54% at 10 microM) (all p < 0.05). Immunohistochemistry of rat aortae 2 h after balloon injury showed a dramatic upregulation of Ets-1, which was markedly inhibited in animals that had received troglitazone treatment. In contrast, phosphorylated ERK MAPK was not affected by troglitazone. These data are consistent with PPAR-gamma ligands exerting their anti-migratory effects downstream of ERK MAPK activation by blocking nuclear events, such as Ets-1 expression, required for cell invasion in response to arterial injury.
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MESH Headings
- Animals
- Aortic Diseases/etiology
- Aortic Diseases/metabolism
- Aortic Diseases/pathology
- Cell Adhesion/drug effects
- Cell Movement/drug effects
- Cell Nucleus/enzymology
- Cells, Cultured
- Chromans/pharmacology
- Cytosol/enzymology
- Enzyme Inhibitors/pharmacology
- Graft Occlusion, Vascular/etiology
- Graft Occlusion, Vascular/metabolism
- Graft Occlusion, Vascular/pathology
- Ligands
- MAP Kinase Signaling System/drug effects
- Male
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/physiology
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/physiology
- Proto-Oncogene Protein c-ets-1
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-ets
- Rats
- Rats, Sprague-Dawley
- Receptors, Cytoplasmic and Nuclear/agonists
- Receptors, Cytoplasmic and Nuclear/metabolism
- Rosiglitazone
- Thiazoles/pharmacology
- Thiazolidinediones
- Transcription Factors/agonists
- Transcription Factors/metabolism
- Transcriptional Activation
- Troglitazone
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Affiliation(s)
- S Goetze
- Department of Medicine/Cardiology, Charité, Campus Virchow Klinikum, Humboldt University Berlin and German Heart Institute Berlin, Augustenbergerplatz 1, 13353 Berlin, Germany.
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6
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Abstract
Atherosclerosis is a major vascular complication of diabetes and the primary cause of mortality in persons with this disease. Metabolic abnormalities related to the Insulin Resistance Syndrome or Metabolic Syndrome may importantly contribute to the increased risk of atherosclerosis associated with diabetes. Thiazolidinediones (TZDs) are oral insulin sensitizers in broad clinical use that enhance insulin-stimulated glucose uptake into skeletal muscle. TZDs can also improve cardiovascular risk factors and exert direct effects on vascular cells to potentially retard the atherosclerotic process. Direct vascular effects of TZDs likely result from their activity as ligands for the nuclear receptor, PPARgamma. All of the major cell types in the vasculature express PPARgamma, including intimal macrophages and vascular smooth muscle cells (VSMCs) in human atheroma. TZDs block VSMC growth by inducing cell cycle arrest in G1 through an inhibition of retinoblastoma protein phosphorylation. Migration of monocytes and VSMCs is also inhibited by TZDs, possibly through decreased matrix metalloproteinase production. Activation of PPARgamma by TZDs in macrophages induces ABCA1 transporter expression to promote reverse cholesterol transport. These antiatherogenic activities may also occur in vivo because TZDs have been shown to inhibit lesion formation in several animal models. Thus, TZD activation of PPARgamma may protect against atherosclerosis both by normalizing proatherogenic metabolic abnormalities of the insulin resistance/diabetes milieu and through an inhibition of vascular cell growth and movement.
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Affiliation(s)
- W A Hsueh
- Division of Endocrinology, Diabetes and Hypertension, UCLA, Department of Medicine, Los Angeles, CA, USA.
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Goetze S, Kintscher U, Kaneshiro K, Meehan WP, Collins A, Fleck E, Hsueh WA, Law RE. TNFalpha induces expression of transcription factors c-fos, Egr-1, and Ets-1 in vascular lesions through extracellular signal-regulated kinases 1/2. Atherosclerosis 2001; 159:93-101. [PMID: 11689211 DOI: 10.1016/s0021-9150(01)00497-x] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Migration, proliferation and differentiation of vascular smooth muscle cells (VSMC) and macrophages are important pathological responses that contribute to the development and progression of vascular lesions. Cytokines such as TNFalpha are present at sites of vascular injury and regulate a variety of cellular functions of inflammatory cells and VSMC. Cell migration, proliferation and differentiation require de novo gene transcription resulting from extracellular signals being transduced to the nucleus, where multiple genes are regulated to participate in lesion formation. In VSMC and macrophages, TNFalpha induces activation of the extracellular signal-regulated kinases 1/2 (ERK 1/2), which transmit signals from the cytosol to the nucleus. Potential nuclear targets of TNFalpha-activated ERK 1/2 include the transcription factors Ets-1, Egr-1, and c-fos, which are known to regulate cellular growth, differentiation, and migration. The aim of this study was to investigate the expression of the transcription factors Ets-1, Egr-1 and c-fos in different types of vascular lesions, their regulation by TNFalpha and the role of ERK 1/2 in these signaling events. Atherosclerotic lesions from fructose-fed LDL-receptor deficient mice and neointimal lesions from rat aortae 2 weeks post balloon injury demonstrated the presence and colocalization of TNFalpha, phosphorylated and activated ERK 1/2, and transcription factors Ets-1, Egr-1 and c-fos. Neointimal lesions consisted primarily of VSMC, whereas atherosclerotic lesions predominantly contained macrophages. In cultured rat aortic VSMC, TNFalpha (100 U/ml) stimulated a rapid and transient expression of Ets-1, Egr-1 and c-fos with a maximal induction 1 h after stimulation. In cultured RAW 264.7 mouse macrophages, TNFalpha similarly induced the expression of Ets-1, Egr-1, and c-fos. Induction of these transcription factors was mediated via ERK 1/2 activation, since the ERK 1/2-pathway inhibitor PD98059 (10-30 microM) significantly inhibited their TNFalpha-induced expression. TNFalpha induced ERK 1/2 activation in both cell types. These findings underscore the importance of the ERK 1/2 pathway in the expression of TNFalpha-regulated transcription factors, which may participate in different forms of vascular lesion formation.
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Affiliation(s)
- S Goetze
- Department of Medicine/Cardiology, Virchow Klinikum, Humboldt University Berlin and German Heart Institute Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
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8
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Goetze S, Blaschke F, Stawowy P, Bruemmer D, Spencer C, Graf K, Gräfe M, Law RE, Fleck E. TNFalpha inhibits insulin's antiapoptotic signaling in vascular smooth muscle cells. Biochem Biophys Res Commun 2001; 287:662-70. [PMID: 11563846 DOI: 10.1006/bbrc.2001.5642] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tumor necrosis factor alpha (TNFalpha) interferes with insulin signaling in adipose tissue and may promote insulin resistance. Insulin resistance is associated with vascular injury, but little is known about the interaction of TNFalpha and insulin in the vasculature. By activating the Insulin receptor (IR) --> IRS-1 --> phosphatidylinositol-3-kinase (PI3K) --> Akt-pathway, insulin protects vascular smooth muscle cells (VSMC) from undergoing apoptosis. We therefore investigated the effect of TNFalpha on insulin's antiapoptotic signaling in rat aortic VSMC. Insulin induced rapid tyrosine-phosphorylation of the IR and IRS-1 and caused a 2.8-fold increase of IRS-1-bound PI3K. TNFalpha had no effect on insulin-induced tyrosine-phosphorylation of IR or IRS-1, but inhibited insulin-stimulated IRS-1/PI3K-association by 84%. Insulin-induced phosphorylation of Akt downstream of PI3K was inhibited by TNFalpha in a similar pattern. We next examined the effect of TNFalpha on insulin's protective actions on H(2)O(2)-induced apoptosis. Insulin alone prevented 72.8% of H(2)O(2)-induced apoptosis, which was significantly inhibited by TNFalpha. TNFalpha alone did not induce apoptosis. In contrast, TNFalpha had no effect on PDGF-induced antiapoptotic signal transduction via Akt. Thus, TNFalpha selectively interferes with insulin's antiapoptotic signaling in VSMC by inhibiting the association of IRS-1/PI3K and the downstream activation of Akt.
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Affiliation(s)
- S Goetze
- Department of Medicine/Cardiology, German Heart Institute Berlin, Berlin, 13353, Germany.
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9
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Yin F, Wakino S, Liu Z, Kim S, Hsueh WA, Collins AR, Van Herle AJ, Law RE. Troglitazone inhibits growth of MCF-7 breast carcinoma cells by targeting G1 cell cycle regulators. Biochem Biophys Res Commun 2001; 286:916-22. [PMID: 11527386 DOI: 10.1006/bbrc.2001.5491] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Peroxisome proliferator activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily. Ligand activation of PPARgamma has been shown to cause growth arrest in several human tumor cell types, but the underlying molecular mechanism has not been elucidated. We report here that the PPARgamma ligand troglitazone (TRO) inhibited MCF-7 cell proliferation by blocking events critical for G1 --> S progression. Flow cytometry demonstrated that TRO at 20 microM increased the percentage of cells in G1 from 51 to 69% after 24 h. Accumulation of cells in G1 was accompanied by an attenuation of Rb protein phosphorylation associated with decreased CDK4 and CDK2 activities. Inhibition of CDK activity by TRO correlates with decreased protein levels for several G1 regulators of Rb phosphorylation (cyclin D1, and CDKs 2, 4, and 6). Overexpression of cyclin D1 partially rescued MCF-7 cells from TRO-mediated G1 arrest. Targeting of G1 regulatory proteins, particularly cyclin D1, and the resulting induction of G1 arrest by TRO may provide a novel antiproliferative therapy for human breast cancer.
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Affiliation(s)
- F Yin
- Division of Endocrinology, Diabetes and Hypertension, UCLA School of Medicine, Los Angeles, California 90095, USA
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10
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Wakino S, Kintscher U, Kim S, Jackson S, Yin F, Nagpal S, Chandraratna RA, Hsueh WA, Law RE. Retinoids inhibit proliferation of human coronary smooth muscle cells by modulating cell cycle regulators. Arterioscler Thromb Vasc Biol 2001; 21:746-51. [PMID: 11348869 DOI: 10.1161/01.atv.21.5.746] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Retinoids inhibit rat vascular smooth muscle cell (VSMC) proliferation in vitro and intimal hyperplasia in vivo. We examined the mechanism of the antiproliferative effect of retinoids on human coronary artery smooth muscle cells (human CASMCs). The RAR ligands all-trans-retinoic acid (atRA) and ethyl-p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-l-propenyl]-benzoic acid (TTNPB); a pan-RXR/RAR agonist, 9-cis-retinoic acid (9cRA); and the RXR-selective ligand AGN4204 all inhibited DNA synthesis stimulated with platelet-derived growth factor and insulin (IC(50): TTNPB 63 nmol/L, atRA 120 nmol/L, AGN4204 460 nmol/L, 9cRA 1.5 micromol/L). All retinoids blocked cell cycle progression as determined by flow cytometry and inhibited retinoblastoma protein (Rb) phosphorylation. TTNPB, atRA, and AGN4204 inhibited the mitogenic induction of cyclin D1, whereas 9cRA had no effect. None of the retinoids affected the expression of CDK 2, 4, or 6 or cyclin E. All retinoids attenuated mitogen-induced downregulation of CDKI p27(Kip1), a major negative regulator of Rb phosphorylation, partly through stabilizing p27(Kip1) turnover. These data demonstrate that retinoids have antiproliferative activity by modulating G(1) --> S cell cycle regulators in human CASMCs through inhibition of Rb phosphorylation and elevation of p27(Kip1) levels.
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Affiliation(s)
- S Wakino
- Division of Endocrinology, Diabetes, and Hypertension, School of Medicine, University of California, Los Angeles 90095, USA
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11
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Abstract
Monocyte chemotactic protein 1 (MCP-1)-directed transendothelial migration of monocytes plays a key role in the early development of atherosclerosis. Migration of monocytes requires degradation of extracellular matrices, a process that involves matrix metalloproteinases (MMP) and tissue inhibitors of MMPs (TIMP). Recent studies suggest that the alpha1-adrenergic receptor antagonist doxazosin (Dox) might have antiatherosclerotic effects, although the underlying mechanisms are poorly understood. The purpose of the present study was to determine the effects of Dox on MCP-1-directed monocyte migration, MMP-9 activity, and TIMP-1 expression. MCP-1 (50 ng/ml) stimulated migration of human peripheral blood monocytes (HPBM) 2.7+/-0.42-fold and THP-1 human monocytes 5.9+/-0.83-fold compared with unstimulated control. Dox inhibited MCP-1-induced migration in a dose-dependent manner, with a maximal reduction at 10 microM of 69.5+/-5.9% in HPBM and 72.2+/-3.2% in THP-1 cells. Dox blocked migration even after pretreatment with phenoxybenzamine, an irreversible alpha1-adrenergic receptor antagonist (HPBM: phenoxybenzamine 1 microM + Dox 10 microM, 71.9+/-2.2% inhibition; THP-1 cells: phenoxybenzamine 1 microM + Dox 10 microM: 78+/-7.7% inhibition), suggesting that the antimigratory activity of Dox is mediated through a novel mechanism unrelated to its blocking of the alpha1-adrenergic receptor. Dox (10 microM) inhibited MMP-9 activity by 67.6+/-10.5%, whereas MMP-9 protein levels were not affected. Also, Dox increased PMA-induced-tissue inhibitor of MMPs-1 (TIMP-1) expression by 134.4+/-6.6%. Dox 10 microM. The present study demonstrates a potential novel antiatherosclerotic action of Dox by blocking MCP-1-directed monocyte migration, which might be partly mediated by inhibition of MMP-9 activity.
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Affiliation(s)
- U Kintscher
- University of California, Los Angeles, School of Medicine, Division of Endocrinology, Diabetes and Hypertension, 90095, USA
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12
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Murata T, Hata Y, Ishibashi T, Kim S, Hsueh WA, Law RE, Hinton DR. Response of experimental retinal neovascularization to thiazolidinediones. Arch Ophthalmol 2001; 119:709-17. [PMID: 11346398 DOI: 10.1001/archopht.119.5.709] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To determine the effect of thiazolidinediones (TZDs) on experimental retinal neovascularization. METHODS The ability of the TZDs troglitazone and rosiglitazone maleate (1-20 micromol/L) to inhibit retinal endothelial cell (REC) proliferation, migration, tube formation, and signaling was determined in response to vascular endothelial growth factor (VEGF). In vivo studies were performed using the oxygen-induced ischemia model of retinal neovascularization. Neonatal mice were treated with intravitreous injection of 0.5 microL of troglitazone (100 micromol/L) or rosiglitazone maleate (100 micromol/L), or vehicle, and retinal neovascularization was assayed qualitatively and quantitatively by means of angiography and histological examination. RESULTS Expression of the TZD receptor, peroxisome proliferator-activated receptor gamma, was confirmed in RECs by means of Western immunoblotting. Rosiglitazone and troglitazone inhibited VEGF-induced migration (P< .05), proliferation (P< .05), and tube formation (P< .01) by RECs in vitro beginning at 10 micromol/L. Rosiglitazone and troglitazone inhibited phosphorylation of extracellular signal-regulated mitogen-activated protein kinase 1 in RECs. Intravitreous injection of rosiglitazone or troglitazone inhibited development of retinal neovascularization (P< .01) but did not significantly inhibit VEGF overexpression in the ganglion cell layer of the ischemic retina. CONCLUSION The TZDs inhibit experimental retinal neovascularization with an effect that is primarily downstream of VEGF expression. CLINICAL RELEVANCE The TZDs are widely prescribed and should be evaluated for their potential to inhibit the progression of diabetic retinopathy.
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Affiliation(s)
- T Murata
- Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA
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13
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Collins AR, Meehan WP, Kintscher U, Jackson S, Wakino S, Noh G, Palinski W, Hsueh WA, Law RE. Troglitazone inhibits formation of early atherosclerotic lesions in diabetic and nondiabetic low density lipoprotein receptor-deficient mice. Arterioscler Thromb Vasc Biol 2001; 21:365-71. [PMID: 11231915 DOI: 10.1161/01.atv.21.3.365] [Citation(s) in RCA: 251] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a ligand-activated nuclear receptor expressed in all of the major cell types found in atherosclerotic lesions: monocytes/macrophages, endothelial cells, and smooth muscle cells. In vitro, PPARgamma ligands inhibit cell proliferation and migration, 2 processes critical for vascular lesion formation. In contrast to these putative antiatherogenic activities, PPARgamma has been shown in vitro to upregulate the CD36 scavenger receptor, which could promote foam cell formation. Thus, it is unclear what impact PPARgamma activation will have on the development and progression of atherosclerosis. This issue is important because thiazolidinediones, which are ligands for PPARgamma, have recently been approved for the treatment of type 2 diabetes, a state of accelerated atherosclerosis. We report herein that the PPARgamma ligand, troglitazone, inhibited lesion formation in male low density lipoprotein receptor-deficient mice fed either a high-fat diet, which also induces type 2 diabetes, or a high-fructose diet. Troglitazone decreased the accumulation of macrophages in intimal xanthomas, consistent with our in vitro observation that troglitazone and another thiazolidinedione, rosiglitazone, inhibited monocyte chemoattractant protein-1-directed transendothelial migration of monocytes. Although troglitazone had some beneficial effects on metabolic risk factors (in particular, a reduction of insulin levels in the diabetic model), none of the systemic cardiovascular risk factors was consistently improved in either model. These observations suggest that the inhibition of early atherosclerotic lesion formation by troglitazone may result, at least in part, from direct effects of PPARgamma activation in the artery wall.
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MESH Headings
- Animals
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/metabolism
- Aorta/drug effects
- Aorta/metabolism
- Aorta/pathology
- Arteriosclerosis/etiology
- Arteriosclerosis/prevention & control
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Body Weight/drug effects
- Cell Movement/drug effects
- Cells, Cultured
- Chemokine CCL2/pharmacology
- Chromans/pharmacology
- Diabetes Mellitus, Type 2/complications
- Dietary Carbohydrates/administration & dosage
- Dietary Fats/administration & dosage
- Endothelium, Vascular/cytology
- Flavonoids/pharmacology
- Fructose/administration & dosage
- Humans
- Insulin/blood
- Lipids/blood
- Macrophages/cytology
- Macrophages/drug effects
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Monocytes/cytology
- Monocytes/drug effects
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Rosiglitazone
- Thiazoles/pharmacology
- Thiazolidinediones
- Troglitazone
- Tumor Cells, Cultured
- Vasodilator Agents/pharmacology
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Affiliation(s)
- A R Collins
- Division of Endocrinology, Diabetes, and Hypertension, Department of Medicine, UCLA School of Medicine, Los Angeles, California, USA
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14
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Abstract
Compared with nondiabetic subjects, type 2 diabetic individuals are at an increased risk for coronary artery disease and coronary restenosis after angioplasty or stenting. Increased proliferation and migration of vascular smooth muscle cells (VSMCs) contribute importantly to the formation of both atherosclerotic and restenotic lesions. Therefore, pharmaceutical interventions targeting proteins that regulate VSMC growth or movement are a promising new approach to treat diabetes-associated cardiovascular disease. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a member of the nuclear receptor superfamily that, when activated by thiazolidinedione (TZD) insulin sensitizers, regulates a host of target genes. All of the major cells in the vasculature express PPAR-gamma, including endothelial cells, VSMCs, and monocytes/macrophages. PPAR-gamma is present in intimal macrophages and VSMCs in early human atheromas. In an animal model of vascular injury; PPAR-gamma levels are substantially elevated in the neointima that forms after mechanical injury of the endothelium. Recent experimental studies provide evidence that PPAR-gamma may function to protect the vasculature from injury. Cell culture studies have shown that TZD PPAR-gamma ligands inhibit both the proliferation and migration of VSMCs. These antiatherogenic activities of PPAR-gamma may also occur in vivo, because TZDs inhibit lesion formation in several animal models. PPAR-gamma ligands may also protect the vasculature indirectly by normalizing metabolic abnormalities of the diabetic milieu that increase cardiovascular risk. Activation of PPAR-gamma, newly defined in vascular cells, may be a useful approach to protect the vasculature in diabetes.
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Affiliation(s)
- W A Hsueh
- Department of Medicine, University of California School of Medicine, Los Angeles 90095-7073, USA
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15
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Abstract
Angiotensin (Ang) II has been shown to enhance the development of atherosclerotic lesions. Migration of monocytes is an early critical step in the atherosclerotic process. To elucidate mechanisms by which Ang II promotes atherogenesis, we investigated its effects on human monocyte migration. Ang II induced migration of human peripheral blood monocytes (HPBM) and human THP-1 monocytes at concentrations between 0.01 and 1 micromol/L, with a 3.6+/-0.6-fold induction in HPBM and a 4.8+/-0.9-fold induction in THP-1 cells at 1 micromol/L Ang II (both P<0.01 versus unstimulated cells). Addition of the Ang II receptor type 1 (AT1-R) antagonist losartan (1 to 100 micromol/L) suppressed Ang II-induced migration of HPBM and THP-1 monocytes in a dose-dependent manner, demonstrating an AT1-R-mediated mechanism. Ang II-directed migration was also blocked by the Src kinase inhibitor PP2 (10 micromol/L), by the extracellular-regulated protein kinase (ERK 1/2) inhibitor PD98059 (30 micromol/L), and by the p38-MAPK inhibitor SB203580 (10 micromol/L), indicating that Src, ERK 1/2, and p38 are all involved in Ang II-induced migration of HPBM and human THP-1 monocytes. The proline-rich tyrosine kinase 2 (Pyk2) and paxillin are 2 cytoskeleton-associated proteins involved in cell movement, phosphorylated by Ang II in other cell types, and abundantly expressed in monocytes. Ang II (1 micromol/L) induced Pyk2 and paxillin phosphorylation in human THP-1 monocytes, peaking after 10 minutes for Pyk2 with a 6.7+/-0.9-fold induction and after 2 minutes for paxillin with a 3.2+/-0.4-fold induction. Ang II-induced phosphorylation of both proteins was suppressed by losartan and the Src inhibitor PP2, whereas no effect was observed with PD98059 and SB203580. This study demonstrates a novel proatherogenic action of Ang II on human monocytes by stimulating their migration, through an AT1-R-dependent process, involving signaling through Src, ERK 1/2, and p38. Furthermore, the promigratory actions of Ang II in human monocytes are associated with the phosphorylation of 2 cytoskeleton-associated proteins, Pyk2 and paxillin.
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Affiliation(s)
- U Kintscher
- University of California Los Angeles School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes, and Hypertension, Los Angeles, California, USA
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16
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Kappert K, Blaschke F, Meehan WP, Kawano H, Grill M, Fleck E, Hsueh WA, Law RE, Graf K. Integrins alphavbeta3 and alphavbeta5 mediate VSMC migration and are elevated during neointima formation in the rat aorta. Basic Res Cardiol 2001; 96:42-9. [PMID: 11215531 DOI: 10.1007/s003950170076] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Neointima formation involves tissue expression of matrix proteins and growth factors. The role of alphavbeta3, but not alphavbeta5 integrin in vascular cells has been sufficiently investigated. The aim of the present study was to determine and compare the function of alphavbeta3 and alphavbeta5 integrins in rat aortic (RASMC) and human coronary vascular smooth muscle cells (HCSMC) and to characterize their expression accompanying neointima formation in vivo. RASMC and HCSMC express alphavbeta3 and alphavbeta5 integrin subunits. The alphavbeta5 integrin predominantly mediated adhesion of RASMCs to vitronectin and spreading on vitronectin via RGD-binding sequences. In contrast, the alphavbeta3 integrin did not contribute to the adhesion and spreading on fibronectin, vitronectin, gelatin or collagen I coated layers. PDGF-directed migration through gelatin coated membranes involved both alphavbeta3 and alphavbeta5 integrins. Selective blocking antibodies for alphavbeta3 and alphavbeta5 inhibited migration of RASMC and HCSMC by more than 60 % (p < 0.01). Integrin expression was studied in vivo in thoracic aorta of Sprague Dawley rats before and after balloon injury. In situ hybridization demonstrated low signals for alphav, beta3 and beta5 mRNA in uninjured aorta, which increased significantly at 14 days, localized predominantly in the neointima. Northern analysis of aorta after 14 days of injury also demonstrated an upregulation of alphav, beta3 and beta5 mRNA compared to uninjured aorta. Consistent with the increase in message levels, increased integrin protein expression was seen in the neointima after 7 and 14 days. This study provides evidence that alphavbeta3 and alphavbeta5 are elevated during neointima formation in the rat and indicates a novel role for alphavbeta5 participating in mechanisms regulating smooth muscle cell migration.
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Affiliation(s)
- K Kappert
- Department of Medicine/Cardiology, Campus Virchow Klinikum der Charité Humboldt Universität Berlin, Germany
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17
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Yin F, Giuliano AE, Law RE, Van Herle AJ. Apigenin inhibits growth and induces G2/M arrest by modulating cyclin-CDK regulators and ERK MAP kinase activation in breast carcinoma cells. Anticancer Res 2001; 21:413-20. [PMID: 11299771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
We have previously reported that apigenin inhibits the growth of thyroid cancer cells by attenuating epidermal growth factor receptor (EGF-R) tyrosine phosphorylation and phosphorylation of ERK mitogen-activated protein (MAP) kinase. In this study, we assessed the growth inhibitory effect of apigenin on MCF-7 breast carcinoma cells that express two key cell cycle regulators, wild-type p53 and the retinoblastoma tumor suppressor protein (Rb), and MDA-MB-468 breast carcinoma cells that are mutant for p53 and Rb negative. We found that apigenin potently inhibited growth of both MCF-7 and MDA-MB-468 breast carcinoma cells. The approximate IC50 values determined after 3 days incubation, were 7.8 micrograms/ml for MCF-7 cells, and 8.9 micrograms/ml for MDA-MB-468 cells, respectively. Because the cell cycle studies using FACS showed that both MCF-7 and MDA-MB-468 cells were arrested in G2/M phase after apigenin treatment, we studied the effects of apigenin on cell cycle regulatory molecules. We observed that G2/M arrest by apigenin involved a significant decrease in cyclin B1 and CDK1 protein levels, resulting in a marked inhibition of CDK1 kinase activity. Apigenin reduced the protein levels of CDK4, cyclins D1 and A, but did not affect cyclin E, CDK2 and CDK6 protein expression. In MCF-7 cells, apigenin markedly reduced Rb phosphorylation after 12 h. We also found that apigenin treatment resulted in a dose- and time-dependent inhibition of ERK MAP kinase phosphorylation and activation in MDA-MB-468 cells. These results suggest that apigenin is a promising antibreast cancer agent and its growth inhibitory effects are mediated by targeting different signal transduction pathways in MCF-7 and MDA-MB-468 breast carcinoma cells.
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Affiliation(s)
- F Yin
- Division of Endocrinology, UCLA School of Medicine, Los Angeles, California 90024, USA
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18
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Kintscher U, Goetze S, Wakino S, Kim S, Nagpal S, Chandraratna RA, Graf K, Fleck E, Hsueh WA, Law RE. Peroxisome proliferator-activated receptor and retinoid X receptor ligands inhibit monocyte chemotactic protein-1-directed migration of monocytes. Eur J Pharmacol 2000; 401:259-70. [PMID: 10936484 DOI: 10.1016/s0014-2999(00)00461-1] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Monocyte chemotactic protein-1 (MCP-1)-directed transendothelial migration of monocytes plays a key role in the development of inflammatory diseases. Infiltration of tissues by monocytes requires degradation of extracellular matrices, a process that involves matrix metalloproteinases. We studied the effects of peroxisome proliferator-activated receptor (PPAR) gamma, alpha, and retinoid X receptor alpha (RXRalpha) ligands on MCP-1-directed migration and matrix metalloproteinase expression of a human acute monocytic leukemia cell line (THP-1). PPARgamma ligands attenuated MCP-1-induced migration, with 50% inhibition (IC(50)) at 2.8 microM for troglitazone and 4.8 microM for rosiglitazone. PPARalpha ligands WY-14643 (IC(50): 0.9 microM) and 5,8,11,14-eicosatetranoic acid (IC(50): 9.9 microM), and the potent RXRalpha ligand AGN 4204 (IC(50): 3.6 nM) also blocked monocyte migration. Troglitazone, rosiglitazone, or AGN 4204 inhibited phorbol 12-myristate 13-acetate (PMA)-induced matrix metalloproteinase-9 expression. PPARalpha activators WY-14643 and 5,8,11,14-eicosatetraynoic acid, however, had no inhibitory effect. AGN 4204 increased PMA-induced tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) expression, whereas all PPAR ligands showed no effect. All PPAR and RXRalpha ligands blocked chemotaxis of THP-1 monocytes in the absence of a matrix barrier. This study demonstrates that activated PPARs and RXRalpha, block MCP-1-directed monocyte migration, mediated, at least in part, through their effects on matrix metalloproteinase-9 or TIMP-1 production, or chemotaxis.
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Affiliation(s)
- U Kintscher
- Division of Endocrinology, Diabetes and Hypertension, School of Medicine, University of California, Los Angeles, Suite 24-130, Warren Hall, 900 Veteran Avenue, 90095, Los Angeles, CA, USA
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19
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Wakino S, Kintscher U, Kim S, Yin F, Hsueh WA, Law RE. Peroxisome proliferator-activated receptor gamma ligands inhibit retinoblastoma phosphorylation and G1--> S transition in vascular smooth muscle cells. J Biol Chem 2000; 275:22435-41. [PMID: 10801895 DOI: 10.1074/jbc.m910452199] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily that is activated by binding certain fatty acids, eicosanoids, and insulin-sensitizing thiazolidinediones (TZD). The TZD troglitazone (TRO) inhibits vascular smooth muscle cell proliferation and migration both in vitro and in vivo. The precise mechanism of its antiproliferative activity, however, has not been elucidated. We report here that PPARgamma ligands inhibit rat aortic vascular smooth muscle cell proliferation by blocking the events critical for G(1) --> S progression. Flow cytometry demonstrated that both TRO and another TZD, rosiglitazone, prevented G(1) --> S progression induced by platelet-derived growth factor and insulin. Movement of cells from G(1) --> S was also inhibited by the non-TZD, natural PPARgamma ligand 15-deoxy-(12,14)Delta prostaglandin J(2) (15d-PGJ(2)), and the mitogen-activated protein kinase pathway inhibitor PD98059. Inhibition of G(1) --> S exit by these compounds was accompanied by a substantial blockade of retinoblastoma protein phosphorylation. TRO and rosiglitazone attenuated both the mitogen-induced degradation of p27(kip1) and the mitogenic induction of p21(cip1). 15d-PGJ(2) and PD98059 inhibited both the degradation of p27(kip1) and the induction of cyclin D1 in response to mitogens. These effects resulted in the inhibition of mitogenic stimulation of cyclin-dependent kinases activated by cyclins D1 and E. These data demonstrate that PPARgamma ligands are antiproliferative drugs that act by modulating cyclin-dependent kinase inhibitors; they may provide a new therapeutic approach for proliferative vascular diseases.
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Affiliation(s)
- S Wakino
- Division of Endocrinology, Diabetes, and Hypertension, Department of Medicine, and the Molecular Biology Institute, UCLA, Los Angeles, California 90095, USA
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20
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Murata T, He S, Hangai M, Ishibashi T, Xi XP, Kim S, Hsueh WA, Ryan SJ, Law RE, Hinton DR. Peroxisome proliferator-activated receptor-gamma ligands inhibit choroidal neovascularization. Invest Ophthalmol Vis Sci 2000; 41:2309-17. [PMID: 10892878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
PURPOSE To determine the antiangiogenic effects of peroxisome proliferator-activated receptor (PPAR)-gamma agonists on ocular cells involved in the pathogenesis of choroidal neovascularization (CNV) in vitro and on experimental laser photocoagulation-induced CNV in vivo. METHODS PPAR-gamma expression in human retinal pigment epithelial (RPE) cells and bovine choroidal endothelial cells (CECs) was determined using an RNase protection assay and Western blot analysis. Two PPAR-gamma ligands, troglitazone (TRO) and rosiglitazone (RSG; 0.1-20 microM), were used to assess effects on RPE and CEC proliferation and migration and CEC tube formation in response to vascular endothelial growth factor (VEGF). The effects of intravitreal injection of TRO on laser photocoagulation-induced CNV lesions in rat eyes (15 experimental, 15 control, nine burns per eye) and cynomolgus monkey eyes (two experimental, two control, seven paramacular burns per eye) was assessed by fluorescein angiography and histologic evaluation. RESULTS. PPAR-gamma1 was expressed in both RPE and CEC. PPAR-gamma ligands significantly inhibited VEGF-induced migration and proliferation in both cell types and tube formation of CEC in a dose-response manner. CNV in rats was markedly inhibited by intravitreous injection of TRO (P < 0.001). Lesions showed significantly less fluorescein leakage and were histologically thinner in the TRO-treated animals. Similar findings were present in the TRO-treated lesions in two monkey eyes. The drug showed no apparent adverse effects in the adjacent retina or in control eyes. CONCLUSIONS The inhibition of VEGF-induced choroidal angiogenesis in vitro, and CNV in vivo by PPAR-gamma ligands suggests the potential application of these agents in the large group of patients with age-related macular degeneration complicated by CNV.
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Affiliation(s)
- T Murata
- Department of Ophthalmology, Doheny Eye Institute, Los Angeles, CA, USA
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21
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Goetze S, Kintscher U, Kawano H, Kawano Y, Wakino S, Fleck E, Hsueh WA, Law RE. Tumor necrosis factor alpha inhibits insulin-induced mitogenic signaling in vascular smooth muscle cells. J Biol Chem 2000; 275:18279-83. [PMID: 10764814 DOI: 10.1074/jbc.m909795199] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tumor necrosis factor alpha (TNFalpha) interferes with insulin signaling in adipose tissue and may promote insulin resistance. Insulin binding to the insulin receptor (IR) triggers its autophosphorylation, resulting in phosphorylation of Shc and the downstream activation of p42/p44 extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase (ERK1/2), which mediates insulin-induced proliferation in vascular smooth muscle cells (VSMC). Since insulin resistance is a risk factor for vascular disease, we examined the effects of TNFalpha on mitogenic signaling by insulin. In rat aortic VSMC, insulin induced rapid phosphorylation of the IR and Shc and caused a 5.3-fold increase in activated, phosphorylated ERK1/2 at 10 min. Insulin induced a biphasic ERK1/2 activation with a transient peak at 10 min and a sustained late phase after 2 h. Preincubation (30-120 min) with TNFalpha had no effect on insulin-induced IR phosphorylation. In contrast, TNFalpha transiently suppressed insulin-induced ERK1/2 activation. Insulin-induced phosphorylation of Shc was inhibited by TNFalpha in a similar pattern. Since mitogenic signaling by insulin in VSMC requires ERK1/2 activation, we examined the effect of TNFalpha on insulin-induced proliferation. Insulin alone induced a 3.4-fold increase in DNA synthesis, which TNFalpha inhibited by 48%. TNFalpha alone was not mitogenic. Inhibition of ERK1/2 activation with PD98059 also inhibited insulin-stimulated DNA synthesis by 57%. TNFalpha did not inhibit platelet-derived growth factor-induced ERK1/2 activation or DNA synthesis in VSMC. Thus, TNFalpha selectively interferes with insulin-induced mitogenic signaling by inhibiting the phosphorylation of Shc and the downstream activation of ERK1/2.
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Affiliation(s)
- S Goetze
- UCLA School of Medicine, Division of Endocrinology, Diabetes and Hypertension, Los Angeles, California 90095, USA
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22
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Kintscher U, Wakino S, Kim S, Jackson SM, Fleck E, Hsueh WA, Law RE. Doxazosin inhibits retinoblastoma protein phosphorylation and G(1)-->S transition in human coronary smooth muscle cells. Arterioscler Thromb Vasc Biol 2000; 20:1216-24. [PMID: 10807736 DOI: 10.1161/01.atv.20.5.1216] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous studies have demonstrated that the alpha(1)-adrenergic receptor antagonist doxazosin (Dox) inhibits multiple mitogenic signaling pathways in human vascular smooth muscle cells. This broad antiproliferative activity of Dox occurs through a novel mechanism unrelated to its blocking the alpha(1)-adrenergic receptor. Flow cytometry demonstrated that Dox prevents mitogen-induced G(1)-->S progression of human coronary artery smooth muscle cells (CASMCs) in a dose-dependent manner, with a maximal reduction of S-phase transition by 88+/-10.5% in 20 ng/mL platelet-derived growth factor and 1 micromol/L insulin (P+I)-stimulated cells (P<0.01 for 10 micromol/L Dox versus P+I alone) and 52+/-18.7% for 10% FBS-induced mitogenesis (P<0.05 for 10 micromol/L Dox versus 10% FBS alone). Inhibition of G(1) exit by Dox was accompanied by a significant blockade of retinoblastoma protein (Rb) phosphorylation. Hypophosphorylated Rb sequesters the E2F transcription factor, leading to G(1) arrest. Adenoviral overexpression of E2F-1 stimulated quiescent CASMCs to progress through G(1) and enter the S phase. E2F-mediated G(1) exit was not affected by Dox, suggesting that it targets events upstream from Rb hyperphosphorylation. Downregulation of the cyclin-dependent kinase inhibitory protein p27 is important for maximal activation of G(1) cyclin/cyclin-dependent kinase holoenzymes to overcome the cell cycle inhibitory activity of Rb. In Western blot analysis, p27 levels decreased after mitogenic stimulation (after P+I, 43+/-1.8% of quiescent cells [P<0.01 versus quiescent cells]; after 10% FBS, 55+/-7.7% of quiescent cells [P<0. 05 versus quiescent cells]), whereas the addition of Dox (10 micromol/L) markedly attenuated its downregulation (after P+I, 90+/-8.3% of quiescent cells [P<0.05 versus P+I alone]; after 10% FBS, 78+/-8.3% of quiescent cells [P<0.05 versus 10% FBS alone]). Furthermore, Dox inhibited cyclin A expression, an E2F regulated gene that is essential for cell cycle progression into the S phase. The present study demonstrates that Dox inhibits CASMC proliferation by blocking cell cycle progression from the G(0)/G(1) phase to the S phase. This G(1)-->S blockade likely results from an inhibition of mitogen-induced Rb hyperphosphorylation through prevention of p27 downregulation.
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Affiliation(s)
- U Kintscher
- Department of Medicine, Division of Endocrinology, Diabetes and Hypertension, School of Medicine, University of California, Los Angeles, USA
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23
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Abstract
Troglitazone (TRO) is an oral insulin-sensitizer that has direct effects on the vasculature to inhibit cell growth and migration. In vascular smooth muscle cells (VSMCs), insulin transduces a mitogenic signal that is dependent on the ERK1/2 MAP kinases. We examined the effects of TRO on this pathway and found that it inhibits mitogenic signaling. In quiescent VSMCs, insulin (1 microM) induced a 3.2-fold increase in DNA synthesis. TRO (1-20 microM) inhibited insulin-stimulated DNA synthesis by 72.8% at the maximal concentration. TRO at I and 10 microM had no significant effect on insulin-stimulated ERK1/2 activity. At 20 microM, however, TRO modestly enhanced insulin-stimulated ERK1/2 activity by 1.5-fold. ERKs transduce a mitogenic signal by phosphorylating transcription factors such as Elk-1. which regulate critical growth-response genes. We used GAL-Elk-1 expression plasmids to detect ERK-dependent activation of Elk-1. TRO at 1-20 microM potently inhibited insulin-stimulated, ERK1/2-dependent Elk-1 transcription factor activity. Neither early steps in insulin signaling nor the phosphatidylinositol 3-kinase (PI3K) branch of this pathway were affected by TRO, because it had no effect on IRS-1 phosphorylation, PI3K/IRS-1 association, or Akt phosphorylation. Because TRO is a known ligand for the nuclear transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), we tested two other ligands for this receptor, rosiglitazone (RSG) and 15-deoxy-delta12,14 prostaglandin J2 (15d-PGJ2). Both also inhibited insulin-induced DNA synthesis. In summary, these data show that TRO inhibits mitogenic signaling by insulin at a point distal of ERK1/2 activation, potentially by a PPARgamma-mediated inhibition of ERK-dependent phosphorylation and activation of nuclear transcription factors that regulate cell growth.
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MESH Headings
- Animals
- Cells, Cultured
- Chromans/pharmacology
- DNA/biosynthesis
- DNA/drug effects
- DNA-Binding Proteins
- Enzyme Activation/drug effects
- Fibroblast Growth Factor 2/metabolism
- Hypoglycemic Agents/pharmacology
- Insulin/metabolism
- Insulin Antagonists/pharmacology
- Insulin Receptor Substrate Proteins
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoproteins/metabolism
- Phosphorylation
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- Rats
- Rats, Sprague-Dawley
- Receptor, Insulin/metabolism
- Receptors, Cytoplasmic and Nuclear/metabolism
- Signal Transduction/drug effects
- Thiazoles/pharmacology
- Thiazolidinediones
- Transcription Factors/metabolism
- Troglitazone
- ets-Domain Protein Elk-1
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Affiliation(s)
- S Goetze
- Division of Endocrinology, Diabetes and Hypertension, University of California, Los Angeles, School of Medicine, 90095, USA
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24
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Abstract
We recently demonstrated that alpha(v)beta(3) integrins are involved in the mechanisms of angiotensin II (Ang II)-induced DNA synthesis and collagen gel contractions in rat cardiac fibroblasts (CFBs), cellular mechanisms that are relevant for cardiac remodeling. The aim of the present study was to elucidate the effect of Ang II and other growth factors on the regulation of the alpha(v)beta(3) integrins in fibroblasts from neonatal rat hearts. The alpha(v)beta(3) integrin receptor expression was significantly increased (P<0.05) at the mRNA level after treatment with Ang II, transforming growth factor-beta(1) (TGF-beta(1)), and platelet-derived growth factor (PDGF) for 8 and 16 hours. The surface expression of the alpha(v) and beta(3) integrin subunits was elevated after 32 and 48 hours (P<0.05) as determined with flow cytometry. To investigate fibroblast motility, we performed chemotaxis experiments with transwell chambers. Ang II was chemotactic for CFBs, as tested with checkerboard experiments. The chemotactic effect was concentration dependent and was completely blocked by Ang II type 1 receptor blockers but not by Ang II type 2 receptor blocker PD 123319. Ang II- and PDGF-BB-mediated chemotaxis could be significantly inhibited by RGD peptides and the blocking antibodies against alpha(v)beta(3) integrin (both P<0.01). Adhesion of CFBs to vitronectin was partially inhibited by an antibody to alpha(v)beta(3) integrin but was mainly mediated by an alpha(v)beta(5) integrin. Relevant in vivo expression of alpha(v)beta(3) integrin by CFBs was confirmed with in situ hybridization with probes for alpha(v) and beta(3) mRNA in rat hearts. The present study demonstrates that the expression of alpha(v)beta(3) integrin is augmented by Ang II, PDGF, and TGF-beta(1) in neonatal CFBs. Furthermore, this integrin is involved in the chemotaxis, motility, and adhesion of CFBs. The present findings support the current concept that integrins participate in the control of fibroblast behavior during cardiac remodeling mechanisms.
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Affiliation(s)
- K Graf
- Division of Endocrinology, Diabetes and Hypertension, University of California Los Angeles, School of Medicine, Los Angeles, CA, USA
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25
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Law RE, Goetze S, Xi XP, Jackson S, Kawano Y, Demer L, Fishbein MC, Meehan WP, Hsueh WA. Expression and function of PPARgamma in rat and human vascular smooth muscle cells. Circulation 2000; 101:1311-8. [PMID: 10725292 DOI: 10.1161/01.cir.101.11.1311] [Citation(s) in RCA: 322] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Peroxisome proliferator-activated receptor-gamma (PPARgamma) is activated by fatty acids, eicosanoids, and insulin-sensitizing thiazolidinediones (TZDs). The TZD troglitazone (TRO) inhibits vascular smooth muscle cell (VSMC) proliferation and migration in vitro and in postinjury intimal hyperplasia. METHODS AND RESULTS Rat and human VSMCs express mRNA and nuclear receptors for PPARgamma1. Three PPARgamma ligands, the TZDs TRO and rosiglitazone and the prostanoid 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2), all inhibited VSMC proliferation and migration. PPARgamma is upregulated in rat neointima at 7 days and 14 days after balloon injury and is also present in early human atheroma and precursor lesions. CONCLUSIONS Pharmacological activation of PPARgamma expressed in VSMCs inhibits their proliferation and migration, potentially limiting restenosis and atherosclerosis. These receptors are upregulated during vascular injury.
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MESH Headings
- 3T3 Cells/physiology
- Animals
- Aorta/injuries
- Aorta/metabolism
- Catheterization
- Cell Division/physiology
- Cell Movement/physiology
- Coronary Artery Disease/metabolism
- Coronary Artery Disease/pathology
- DNA/biosynthesis
- Fibroblast Growth Factor 2/pharmacology
- Humans
- Ligands
- Mice
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Platelet-Derived Growth Factor/pharmacology
- RNA, Messenger/metabolism
- Rats
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Cytoplasmic and Nuclear/physiology
- Subcellular Fractions/metabolism
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription Factors/physiology
- Tunica Intima/metabolism
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Affiliation(s)
- R E Law
- Department of Medicine, University of California at Los Angeles School of Medicine, Los Angeles, CA 90095, USA
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26
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Abstract
BACKGROUND Angiotensin II (Ang II) is implicated in cardiac remodeling and is increasingly recognized for its profibrotic activity. METHODS AND RESULTS Because little is known about the direct cellular effects of Ang II on human cardiac fibroblasts, we isolated fibroblasts from ventricles of explanted human hearts and added Ang II (100 nmol/L) to determine its role in growth, extracellular matrix accumulation, and adhesion. To assess which Ang II receptor is involved, Ang II was added in the presence of irbesartan (10 micromol/L), a specific AT(1) receptor antagonist; PD 123319 (10 micromol/L), a specific AT(2) receptor antagonist, or divalinil (100 nmol/L), an AT(4) receptor inhibitor. In human ventricles (n=13), message levels of atrial natriuretic peptide and AT(1) receptor were inversely correlated, which suggests a decrease in AT(1) receptor expression with progressive heart failure. Northern analysis and fluorescence-activated cell sorting demonstrated AT(1) receptor in cultured human cardiac fibroblasts. Ang II increased mitogen-activated protein kinase activity and in DNA synthesis (5-fold, P<0.01) stimulated a 2-fold increase in transforming growth factor-beta(1) (P<0.05) mRNA levels at 2 hours and a 2-fold increase in laminin (P<0.05) and fibronectin (P<0.05) mRNA levels at 24 hours. Ang II also enhanced plasminogen activator inhibitor-1 expression, which inhibits metalloproteinases that degrade the extracellular matrix. All of these effects were inhibited by irbesartan but not PD 123319 or divalinil. In addition, Ang II increased cardiac fibroblast attachment to collagens I and III, which was associated with an increase in focal adhesion kinase activity. CONCLUSIONS Activation of the AT(1) receptor in human heart promotes fibrosis. Ang II plays a novel role in stimulation of plasminogen activator inhibitor-1 expression and adhesion of cardiac fibroblasts to collagen.
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Affiliation(s)
- H Kawano
- Department of Medicine, Division of Endocrinology, Diabetes, and Hypertension, University of California at Los Angeles School of Medicine, CA 90024, USA
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27
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Kawano H, Cody RJ, Graf K, Goetze S, Kawano Y, Schnee J, Law RE, Hsueh WA. Angiotensin II enhances integrin and alpha-actinin expression in adult rat cardiac fibroblasts. Hypertension 2000; 35:273-9. [PMID: 10642310 DOI: 10.1161/01.hyp.35.1.273] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II (Ang II) plays an important role in cardiac remodeling through stimulation of proliferation and extracellular matrix (ECM) production in cardiac fibroblasts. Integrins are a family of transmembrane receptors that mediate the attachment of cells to ECM. We hypothesized that Ang II regulation of integrins further contributes to its role in cardiac remodeling. We cultured adult rat cardiac fibroblasts with and without Ang II (100 nmol/L) to determine the effects on mRNA and protein levels of integrins, as well as alpha-actinin and other cytoskeletal proteins that link to integrins at the site of focal adhesions. Ang II was also added in the presence of irbesartan (10 micromol/L), a specific Ang II type 1 (AT(1)) receptor antagonist, or PD 123319 (10 micromol/L), a specific Ang II type 2 receptor antagonist. To investigate the function of these integrins, we determined the effects of blocking antibodies on Ang II-induced adhesion to ECM. We also treated spontaneously hypertensive rats (SHR) with an AT(1) receptor blocker, losartan, or with hydralazine to investigate integrin and alpha-actinin expression in treated and untreated SHR. Ang II enhanced alpha(v), beta(1), beta(3), and beta(5) integrins; osteopontin; and alpha-actinin mRNA and protein levels in cardiac fibroblasts. All of these effects were inhibited by irbesartan but not by PD 123319. Pretreatment of cardiac fibroblasts with Ang II enhanced cell attachment to ECM proteins and induced focal adhesion kinase phosphorylation. Blocking antibodies to beta(3) and alpha(v)beta(5) attenuated Ang II-induced adhesion. In SHR, ventricular alpha(v) and beta(5) integrin expression and alpha-actinin were increased compared with those in Wistar-Kyoto rats. Although both losartan and hydralazine lowered mean arterial pressure and decreased peripheral vascular resistance, only losartan attenuated the increased integrin, alpha-actinin, fibronectin laminin, and osteopontin expression and the increased left ventricular mass (as determined with echocardiography). Hydralzine had none of these effects. Although both agents attenuated beta-myosin heavy chain expression, a marker of hypertrophy, losartan had a greater effect. These results suggest that integrins and alpha-actinin are upregulated by Ang II and in left ventricular hypertrophy and that the block of expression of these proteins through inhibition of the AT(1) receptor is associated with attenuation of the hypertrophic response. Ang II induces integrin and alpha-actinin expression in cardiac fibroblasts that is associated with adhesion and left ventricular hypertrophy and blocked through inhibition of the AT(1) receptor.
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MESH Headings
- Actinin/genetics
- Age Factors
- Angiotensin II/pharmacology
- Angiotensin Receptor Antagonists
- Animals
- Antigens, CD/genetics
- Antihypertensive Agents/pharmacology
- Biphenyl Compounds/pharmacology
- Cardiomegaly/physiopathology
- Cell Adhesion/drug effects
- Cell Adhesion Molecules/metabolism
- Cells, Cultured
- Collagen/pharmacology
- Fibroblasts/chemistry
- Fibroblasts/cytology
- Fibroblasts/enzymology
- Fibronectins/pharmacology
- Focal Adhesion Kinase 1
- Focal Adhesion Protein-Tyrosine Kinases
- Gene Expression/drug effects
- Gene Expression/physiology
- Heart Ventricles/chemistry
- Heart Ventricles/cytology
- Heart Ventricles/enzymology
- Hydralazine/pharmacology
- Imidazoles/pharmacology
- Integrin alphaV
- Integrin beta Chains
- Integrin beta1/genetics
- Integrin beta3
- Integrins/genetics
- Irbesartan
- Laminin/pharmacology
- Losartan/pharmacology
- Myocardium/chemistry
- Myocardium/cytology
- Phosphorylation
- Platelet Membrane Glycoproteins/genetics
- Protein-Tyrosine Kinases/metabolism
- Pyridines/pharmacology
- RNA, Messenger/analysis
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/physiology
- Tetrazoles/pharmacology
- Up-Regulation/drug effects
- Up-Regulation/genetics
- Vitronectin/pharmacology
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Affiliation(s)
- H Kawano
- Department of Medicine, Division of Endocrinology, University of California at Los Angeles School of Medicine, 90024, USA
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28
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Jackson SM, Parhami F, Xi XP, Berliner JA, Hsueh WA, Law RE, Demer LL. Peroxisome proliferator-activated receptor activators target human endothelial cells to inhibit leukocyte-endothelial cell interaction. Arterioscler Thromb Vasc Biol 1999; 19:2094-104. [PMID: 10479650 DOI: 10.1161/01.atv.19.9.2094] [Citation(s) in RCA: 279] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
An early event in acute and chronic inflammation and associated diseases such as atherosclerosis and rheumatoid arthritis is the induced expression of specific adhesion molecules on the surface of endothelial cells (ECs), which subsequently bind leukocytes. Peroxisome proliferator-activated receptors (PPARs), members of the nuclear receptor superfamily of transcription factors, are activated by fatty acid metabolites, peroxisome proliferators, and thiazolidinediones and are now recognized as important mediators in the inflammatory response. Whether PPAR activators influence the inflammatory responses of ECs is unknown. We show that the PPAR activators 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), Wyeth 14643, ciglitazone, and troglitazone, but not BRL 49653, partially inhibit the induced expression of vascular cell adhesion molecule-1 (VCAM-1), as measured by ELISA, and monocyte binding to human aortic endothelial cells (HAECs) activated by phorbol 12-myristate 13-acetate (PMA) or lipopolysaccharide. The "natural" PPAR activator 15d-PGJ(2) had the greatest potency and was the only tested molecule capable of partially inhibiting the induced expression of E-selectin and neutrophil-like HL60 cell binding to PMA-activated HAECs. Intracellular adhesion molecule-1 induction by PMA was unaffected by any of the molecules tested. Both PPAR-alpha and PPAR-gamma mRNAs were detected in HAECs by using reverse transcription-polymerase chain reaction and a ribonuclease protection assay; however, we have yet to determine which, if any, of the PPARs are mediating this process. These results suggest that certain PPAR activators may help limit chronic inflammation mediated by VCAM-1 and monocytes without affecting acute inflammation mediated by E-selectin and neutrophil binding.
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Affiliation(s)
- S M Jackson
- Department of Medicine, University of California, Los Angeles, School of Medicine, Los Angeles 90095-1679, USA.
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29
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Abstract
Insulin has several direct vascular actions that contribute to either vascular protection or injury, depending on the cell type. Vascular protective effects of insulin include stimulation of endothelial cell production of the vasodilator nitric oxide (NO). This, in turn, inhibits formation of lesions dependent on migration and proliferation of vascular smooth muscle cells (VSMCs), attenuates binding of inflammatory cells to the vascular wall, and inhibits thrombosis by reducing platelet adhesion and aggregation. However, insulin also promotes a host of deleterious vascular effects by stimulating the actions of various growth factors acting through the mitogen-activated protein kinase (MAPK) signaling pathway. MAPK may mediate the effects of insulin and angiotensin II on VSMC production of plasminogen activator inhibitor-1, which attenuates fibrinolysis. Thus, 1 of the 2 major pathways of insulin action is the phosphatidylinositol 3-kinase pathway, which is important for glucose transport in skeletal muscle, as well as endothelial NO production and insulin-induced vasodilation. The second insulin-activated pathway is the MAPK pathway, which promotes VSMC growth factors and migration induced by insulin, thrombin, angiotensin II, and platelet-derived growth factor. The thiazolidinediones, which act as ligands for peroxisomal proliferator-activated receptor gamma, may inhibit VSMC growth and migration through inhibition of a variety of transcription factors involved in the MAPK pathway.
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Affiliation(s)
- W A Hsueh
- Department of Medicine, University of California Los Angeles School of Medicine, USA
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30
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Goetze S, Xi XP, Graf K, Fleck E, Hsueh WA, Law RE. Troglitazone inhibits angiotensin II-induced extracellular signal-regulated kinase 1/2 nuclear translocation and activation in vascular smooth muscle cells. FEBS Lett 1999; 452:277-82. [PMID: 10386606 DOI: 10.1016/s0014-5793(99)00624-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The thiazolidinedione troglitazone inhibits angiotensin II-induced extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase activity in vascular smooth muscle cells. Activation of extracellular signal-regulated kinase 1/2 by angiotensin II is a multistep process involving both its phosphorylation by mitogen-activated protein kinase extracellular signal-regulated kinase kinase in the cytoplasm and a subsequent translocation to the nucleus. The cytoplasmic activation of extracellular signal-regulated kinase 1/2 in vascular smooth muscle cells proceeds through the protein kinase Czeta --> mitogen-activated protein kinase extracellular signal-regulated kinase kinase --> extracellular signal-regulated kinase pathway. Troglitazone did not affect the angiotensin II-induced activation of protein kinase Czeta or its downstream signaling kinases extracellular signal-regulated kinase 1/2 in the cytosol. In contrast, angiotensin II-induced activation of protein kinase Czeta and extracellular signal-regulated kinase 1/2 in the nucleus were both inhibited by troglitazone. Nuclear translocation of extracellular signal-regulated kinase 1/2 induced by angiotensin II was completely blocked by troglitazone. Protein kinase Czeta, however, did not translocate upon angiotensin II stimulation. Troglitazone, therefore, inhibits both angiotensin II-induced nuclear translocation of extracellular signal-regulated kinase 1/2 and the nuclear activity of its upstream signaling kinase protein kinase Czeta. Since extracellular signal-regulated kinase 1/2 nuclear translocation may be a critical signaling step for multiple growth factors that stimulate vascular smooth muscle cells proliferation and migration, troglitazone may provide a new therapeutical approach for the prevention and treatment of atherosclerosis and restenosis.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cell Nucleus/drug effects
- Cell Nucleus/metabolism
- Cells, Cultured
- Chromans/pharmacology
- Cytoplasm/metabolism
- Kinetics
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Protein Kinase C/metabolism
- Rats
- Rats, Sprague-Dawley
- Signal Transduction/drug effects
- Thiazoles/pharmacology
- Thiazolidinediones
- Troglitazone
- Vasodilator Agents/pharmacology
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Affiliation(s)
- S Goetze
- University of California, Los Angeles, School of Medicine, Division of Endocrinology, Diabetes and Hypertension, 90095, USA
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31
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Goetze S, Xi XP, Kawano H, Gotlibowski T, Fleck E, Hsueh WA, Law RE. PPAR gamma-ligands inhibit migration mediated by multiple chemoattractants in vascular smooth muscle cells. J Cardiovasc Pharmacol 1999; 33:798-806. [PMID: 10226869 DOI: 10.1097/00005344-199905000-00018] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to determine the effect of the peroxisome proliferator-activated receptor gamma-(PPAR gamma) ligands troglitazone (TRO), rosiglitazone (RSG), and 15-deoxy-delta prostaglandin J2 (15d-PGJ2) on vascular smooth muscle cell (VSMC) migration directed by multiple chemoattractants. Involvement of mitogen-activated protein kinase (MAPK) in migration also was examined, because TRO was previously shown to inhibit nuclear events stimulated by this pathway during mitogenic signaling in VSMCs. Migration of rat aortic VSMCs was induced 5.4-fold by PDGF, 4.6-fold by thrombin, and 2.3-fold by insulin-like growth factor I (IGF-I; all values of p < 0.05). The PPAR gamma ligands 15d-PGJ2, RSG, or TRO all inhibited VSMC migration with the following order of potency: 15d-PGJ2 > RSG > TRO. Inhibition of MAPK signaling with PD98059 completely blocked PDGF-, thrombin-, and IGF-I-induced migration. All chemoattractants induced MAPK activation. PPAR gamma ligands did not inhibit MAPK activation, suggesting a nuclear effect of these ligands downstream of MAPK. The importance of nuclear events was confirmed because actinomycin D also blocked migration. We conclude that PPAR gamma ligands are potent inhibitors of VSMC migration pathways, dependent on MAPK and nuclear events. PPAR gamma ligands act downstream of the cytoplasmic activation of MAPK and appear to exert their effects in the nucleus. Because VSMC migration plays an important role in the formation of atherosclerotic lesions and restenosis, PPAR gamma ligands like TRO and RSG, which ameliorate insulin resistance in humans, also may protect the vasculature from diabetes-enhanced injury.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cell Movement/drug effects
- Cells, Cultured
- Chemotactic Factors/pharmacology
- Chemotactic Factors/physiology
- Chromans/pharmacology
- Cycloheximide/pharmacology
- Dactinomycin/pharmacology
- Enzyme Activation
- Insulin-Like Growth Factor I/pharmacology
- Insulin-Like Growth Factor I/physiology
- Ligands
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Platelet-Derived Growth Factor/pharmacology
- Platelet-Derived Growth Factor/physiology
- Prostaglandin D2/analogs & derivatives
- Prostaglandin D2/pharmacology
- Protein Synthesis Inhibitors/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/physiology
- Rosiglitazone
- Thiazoles/pharmacology
- Thiazolidinediones
- Thrombin/pharmacology
- Thrombin/physiology
- Transcription Factors/drug effects
- Transcription Factors/physiology
- Troglitazone
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Affiliation(s)
- S Goetze
- University of California, Los Angeles, School of Medicine, Division of Endocrinology 90095, USA
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32
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Xi XP, Graf K, Goetze S, Fleck E, Hsueh WA, Law RE. Central role of the MAPK pathway in ang II-mediated DNA synthesis and migration in rat vascular smooth muscle cells. Arterioscler Thromb Vasc Biol 1999; 19:73-82. [PMID: 9888869 DOI: 10.1161/01.atv.19.1.73] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II (Ang II) promotes vascular smooth muscle cell (VSMC) growth and migration, but the signaling pathways mediating these VSMC behaviors critical to restenosis and atherosclerosis are not completely known. The purpose of the present investigation was to define the role of mitogen-activated protein kinase (MAPK) in Ang II-induced DNA synthesis, migration, and c-fos induction in VSMCs. PD 98059, a synthetic inhibitor of MAPK kinase, or antisense oligodeoxynucleotides (ODNs) to deplete extracellular signal-regulated kinase (ERK)1 and ERK2 MAPKs, were used to inhibit MAPK signaling. PD 98059 at 30 micromol/L reduced Ang II-induced MAPK activity by 69% (P<0.01). Under these conditions, Ang II-induced DNA synthesis was completely inhibited (P<0.01), and Ang II-directed migration was attenuated by 76% (P<0.05). In contrast, induction of c-fos by Ang II was only partially suppressed (58% inhibition, P<0.01). Antisense ODNs against the initiation site of rat ERK1 and ERK2 MAPK mRNAs reduced corresponding protein levels by 63% (P<0.01) and completely inhibited MAPK activation by either Ang II (1 micromol/L) or 10% serum. Antisense ODNs (0.4 micromol/L) completely inhibited Ang II-induced DNA synthesis (P<0.01), decreased migration by 47% (P<0.01), and reduced c-fos induction by 40% (P<0.01 versus control ODN-transfected VSMCs). The Ang II type 1 (AT1)-receptor blocker irbesartan completely blocked DNA synthesis, migration, MAPK activation, and c-fos induction by Ang II in VSMCs. These results demonstrate that activation of MAPK plays a crucial role in Ang II-directed migration and DNA synthesis through the AT1 receptor. In contrast, Ang II-mediated c-fos induction and migration were only partially inhibited by either antisense ODNs or PD 98059, suggesting that other pathways in addition to the MAPK pathway may be involved in these actions of Ang II. We conclude that MAPK is a critical regulatory factor for Ang II-mediated migration and growth in VSMCs. Ang II-induced DNA synthesis showed a stronger MAPK dependence than did Ang II-directed migration or c-fos induction.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Calcium-Calmodulin-Dependent Protein Kinases/antagonists & inhibitors
- Calcium-Calmodulin-Dependent Protein Kinases/genetics
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cell Movement/drug effects
- DNA/biosynthesis
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Flavonoids/pharmacology
- Mitogen-Activated Protein Kinase 1
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Oligodeoxyribonucleotides, Antisense/pharmacology
- Proto-Oncogene Proteins c-fos/biosynthesis
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/physiology
- Signal Transduction/drug effects
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Affiliation(s)
- X P Xi
- University of California at Los Angeles, School of Medicine, Division of Endocrinology, Diabetes, Los Angeles, CA, USA
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33
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Abstract
-Migration of vascular smooth muscle cells (VSMC) is a key event in neointimal formation and atherosclerosis that may be linked to the accumulation of inflammatory cells and release of chemotactic cytokines. Tumor necrosis factor-alpha (TNF-alpha) induces chemotaxis of inflammatory cells and fibroblasts, but little is known about chemotactic signaling by TNF-alpha in VSMC. The aim of this study was to investigate the role of TNF-alpha in VSMC migration and to elucidate the chemotactic signaling pathways mediating this action. TNF-alpha (50 to 400 U/mL) induced migration of cultured rat aortic VSMC in a dose-dependent manner. Because activation of the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase (MAPK) is known to be required in platelet-derived growth factor-directed and angiotensin II-directed migration of these cells, we used the MAPK-inhibitor PD98059 to determine if chemotactic signaling by TNF-alpha involves the MAPK pathway as well. We found that TNF-alpha-directed migration was substantially inhibited by PD98059. TNF-alpha (100 U/mL) transiently activated MAPK with a maximal induction 10 minutes after stimulation that returned to baseline levels by 2 hours after treatment. Only a single peak of increased MAPK activity was seen. PD98059 also blocked TNF-alpha-stimulated MAPK activation in a concentration-dependent manner, which is consistent with its inhibition of TNF-alpha-directed migration. To identify which TNF-alpha receptor is involved in TNF-alpha-induced MAPK activation, antibodies against the p55 TNF-alpha receptor-1 (TNF-R1) and the p75 TNF-alpha receptor-2 (TNF-R2) were used. VSMC express both receptors, but TNF-alpha-induced MAPK activation was inhibited only by the TNF-R1 antibody. The TNF-R2 antibody had no effect. Thiazolidinediones are known to inhibit TNF-alpha signaling in adipose tissue and attenuate platelet-derived growth factor-directed and angiotensin II-directed migration in VSMC. We therefore investigated the effects of the thiazolidinediones troglitazone (TRO) and rosiglitazone (RSG) on TNF-alpha-induced migration. Both TRO and RSG inhibited migration, but neither attenuated TNF-alpha-induced MAPK activation, indicating that their antimigration activity was exerted downstream of MAPK. These experiments provide the first evidence that early activation of MAPK is a crucial event in TNF-alpha-mediated signal transduction leading to VSMC migration. Moreover, inhibition of TNF-alpha-directed migration by the insulin sensitizers TRO and RSG underscores their potential as vasculoprotective agents.
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MESH Headings
- Analysis of Variance
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/enzymology
- Aorta, Thoracic/physiology
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cells, Cultured
- Chemotaxis/drug effects
- Chemotaxis/physiology
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Flavonoids/pharmacology
- Kinetics
- Mitogen-Activated Protein Kinase 1
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/physiology
- Rats
- Rats, Sprague-Dawley
- Recombinant Proteins/pharmacology
- Tumor Necrosis Factor-alpha/pharmacology
- Tumor Necrosis Factor-alpha/physiology
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Affiliation(s)
- S Goetze
- Division of Endocrinology, Diabetes and Hypertension, University of California, Los Angeles, School of Medicine 90095, USA
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34
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Hsueh WA, Law RE. Diabetes is a vascular disease. J Investig Med 1998; 46:387-90. [PMID: 9805424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- W A Hsueh
- University of California, Los Angeles, Division of Endocrinology, Diabetes and Hypertension, USA
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35
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Abstract
Although low-density lipoprotein (LDL) cholesterol is a critically important factor in the development of atherosclerosis, nearly half the patients with coronary artery disease have LDL cholesterol levels within the National Cholesterol Education Program (NCEP) guidelines. Therefore, attention has focused on other modifiable risk factors that could strongly impact the development of coronary artery disease. Type 2 diabetics have a 3-fold increased risk of coronary artery disease; prediabetics, without chronic hyperglycemia, have a 2-fold increased risk compared with normal subjects. Insulin resistance has also been implicated as the cause of atherosclerosis. Insulin resistance is associated with hyperinsulinemia and a constellation of other factors, some of which are themselves independent risk factors for coronary artery disease. These include reduced levels of high-density lipoprotein (HDL) cholesterol, hypertriglyceridemia, increased small dense LDL particles, hypertension, visceral obesity, and increased levels of plasminogen activator inhibitor-1 (PAI-1). Hyperinsulinemia and insulin resistance at the vascular level also may contribute to vascular injury and the atherosclerotic process. Current studies suggest that controlling hyperglycemia, LDL cholesterol, and blood pressure are important to protect the diabetic from atherosclerosis. A key question, particularly in type 2 diabetes, is to define the best regimen for glucose control that will protect the vasculature. Sulfonylureas, metformin, and troglitazone have direct vascular actions. Metformin lowers LDL cholesterol and triglycerides, while troglitazone reverses many of the components associated with the insulin resistance syndrome. Clinical trials focusing on coronary artery disease outcomes are now warranted to prevent coronary artery disease, the major vascular complication and cause of mortality in diabetes.
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Affiliation(s)
- W A Hsueh
- Department of Medicine, University of California/Los Angeles, School of Medicine, USA
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36
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Hinton DR, He S, Graf K, Yang D, Hsueh WA, Ryan SJ, Law RE. Mitogen-activated protein kinase activation mediates PDGF-directed migration of RPE cells. Exp Cell Res 1998; 239:11-5. [PMID: 9511719 DOI: 10.1006/excr.1997.3873] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Growth factor-directed migration is a critical component of the wound healing response although little is known about the signaling pathways involved. We examined the effect of inhibiting the mitogen-activated protein kinase (MAPK) pathway on platelet-derived growth factor (PDGF) and fibronectin-induced cell migration of human retinal pigment epithelial (RPE) cells. Using transwell cell-culture chambers, the effect of PDGF-BB (10-50 ng/ml) and fibronectin on components of migration was measured with or without the MAPK pathway inhibitor PD98059 (10-30 microM) MAPK activation of serum-starved cells by PDGF-BB was demonstrated by an immunoprecipitation/kinase assay and by immunohistochemistry using antibody specific for phosphorylated MAPK. PDGF-BB (10 ng/ml) stimulated MAPK activity in RPE (10 min) and its nuclear localization (1 h). PD98059 inhibited the activation of MAPK by PDGF-BB or serum. PDGF-BB stimulated RPE chemokinesis, chemotaxis, and haptotaxis; chemokinesis was additively increased and chemotaxis synergistically increased by the presence of a fibronectin substratum. PD98059 potently inhibited fibronectin-induced haptotaxis and PDGF-BB-induced chemotaxis but inhibited chemokinesis only at higher PDGF-BB (50 ng/ml) concentrations in the presence of fibronectin substratum. These results demonstrate that MAPK is critically involved in multiple components of RPE migration in vitro and suggest the potential of targeting MAPK to inhibit RPE migration in vivo.
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Affiliation(s)
- D R Hinton
- Department of Pathology, University of Southern California School of Medicine, Los Angeles 90033, USA
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37
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Abstract
Integrins are heterodimeric cell surface receptors that mediate a cell's ability to perceive its environment, respond to changed in its environment, and alter its environment. When activated, these receptors form focal adhesions, which are areas of close attachment of the cells to extracellular matrix proteins in which colocalization of cytoskeletal proteins, intracellular signaling molecules, and growth factor receptors occurs. In cardiac fibroblasts, integrins mediate cell growth and adhesion. Growth factors such as angiotensin II regulate DNA synthesis, protooncogene expression, extracellular matrix production, adhesion, and other actions of cardiac fibroblasts, many of which require integrin activation. In addition to controlling growth factor and hemodynamic effects, regulation ofintegrin activity may be useful to affect cardiac fibrosis and the remodeling process.
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Affiliation(s)
- W A Hsueh
- University of California at Los Angeles, School of Medicine, Department of Medicine, 90095-7073, USA
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38
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Zhang W, Law RE, Hinton DR, Couldwell WT. Inhibition of human malignant glioma cell motility and invasion in vitro by hypericin, a potent protein kinase C inhibitor. Cancer Lett 1997; 120:31-8. [PMID: 9570383 DOI: 10.1016/s0304-3835(97)00287-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The effect of hypericin, an antiviral drug and a potent protein kinase C (PKC) inhibitor, on glioma cell invasion was investigated in vitro. Treatment of the established human glioblastoma cell line, T98G, with 1 microM hypericin for 24 h resulted in a significant inhibition of the cell invasion through an artificial basement membrane, but not cell attachment or proliferation. Furthermore, tamoxifen and staurosporine, both PKC inhibitors, also inhibited T98G cell invasion, suggesting that PKC may be the cellular target for hypericin-inhibited glioma cell migration. Similarly, hypericin decreased cell motility significantly in established lines, T98G and U87-MG, and also in a low-passage human malignant glioma cell line. Thus, hypericin may prove useful for studying mechanisms of glioma invasion, and may represent a new agent in malignant glioma therapy.
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Affiliation(s)
- W Zhang
- Department of Neuroscience, University of North Dakota School of Medicine, Grand Forks, USA
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39
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Xi XP, Graf K, Goetze S, Hsueh WA, Law RE. Inhibition of MAP kinase blocks insulin-mediated DNA synthesis and transcriptional activation of c-fos by Elk-1 in vascular smooth muscle cells. FEBS Lett 1997; 417:283-6. [PMID: 9409734 DOI: 10.1016/s0014-5793(97)01303-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Insulin-stimulated DNA synthesis, MAP kinase (MAPK) activity and c-fos expression in vascular smooth muscle cells (VSMCs) was blocked by the MAPK inhibitor PD 98059. Regulation of c-fos expression by the transcription factor Elk-1 at the serum response element (SRE) is dependent on its phosphorylation by MAPK. PD 98059 also suppressed insulin-induced Elk-1 transcriptional activity through the SRE. These data show that MAPK plays a critical role in both insulin-mediated growth and Elk-1-dependent induction of c-fos in VSMCs.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Calcium-Calmodulin-Dependent Protein Kinases/antagonists & inhibitors
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cells, Cultured
- DNA-Binding Proteins
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Flavonoids/pharmacology
- Genes, fos/drug effects
- Insulin/pharmacology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-fos/biosynthesis
- RNA, Messenger/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Transcription Factors/metabolism
- Transcription, Genetic/drug effects
- Transcriptional Activation/drug effects
- Transcriptional Activation/physiology
- ets-Domain Protein Elk-1
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Affiliation(s)
- X P Xi
- University of California, Los Angeles, School of Medicine 90024, USA
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40
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Imam SA, Kim MS, Anker L, Datar RH, Law RE, Taylor CR. Systematic determination of telomerase activity and telomerase length during the progression of human breast cancer in cell culture models. Anticancer Res 1997; 17:4435-41. [PMID: 9494546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The purpose of the study was to determine systematically the expression of telomerase activity and the length of telomere repeat arrays by utilizing two different cell culture models that derive from normal individual donors, and probably represent various stages of human breast oncogenesis in cell culture. The models consist of mortal, non-tumorigenic immortal and tumorigenic immortal human mammary epithelial cell (MEC) lines. Using a recently developed polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay, telomerase activity was undetectable in mortal MEC cells. In contrast, the immortal MEC that were nontumorigenic or tumorigenic in immunosuppressed athymic mice, showed telomerase activity. The absence of telomerase activity in mortal and its presence in both non-tumorigenic and tumorigenic immortal cell lines did not reflect their proliferative rate, as demonstrated by the similar pattern and intensity of reactivity of these cell lines with anti-Ki 67 antibody which recognizes a human nuclear cell proliferation--associated antigen. Southern blot analyses of Hinf I-digested genomic DNA hybridized with a (TTAGGG)4 probe revealed arrays of telomeric repeat lengths ranging from 3 to 5, 3.5 to 9, 3.2 to 9 or 3 to 15 kilobase pair (kbp) for mortal, nontumorigenic immortal, and tumorigenic immortal or established MEC lines respectively. These results suggest that telomerase activity and stable telomeric repeat lengths may be a molecular phenotype of the early stages in the progression of breast cancer.
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Affiliation(s)
- S A Imam
- Department of Pathology, University of Southern California, School of Medicine, Los Angeles 90033, USA
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41
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Cloughesy TF, Woods RP, Black KL, Couldwell WT, Law RE, Hinton DR. Prolonged treatment with biologic agents for malignant glioma: a case study with high dose tamoxifen. J Neurooncol 1997; 35:39-45. [PMID: 9266439 DOI: 10.1023/a:1005895616377] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Traditional study design for treatment of malignant gliomas does not allow tumor progression to be greater than 25-50 percent without terminating treatment. This design may prevent recognition of patients who benefit from the treatment either by slowed growth or delayed response. A delayed response or slowed growth may be characteristic of biologic agents being evaluated in the treatment of malignant glioma. Because of the low toxicity of certain biologic drugs, continued treatment through tumor growth can be ethically considered in study design. The effect of biologic agents on a neoplasm may include cellular differentiation, retardation of growth, cytostasis, cytocidal effects, or apoptosis. Such effects may clinically translate into a complete response, partial response, stable disease or retardation of growth with or without an eventual reduction of tumor. We present a patient with a recurrent malignant glioma who was continued on high dose tamoxifen despite radiologic documented doubling of the tumor size and who eventually showed a delayed response to this agent nine months after initiation of treatment. Strong consideration should be given to the prolonged treatment of non-toxic biologic agents in a controlled clinical trial, where agents have shown some benefit in phase one studies.
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Affiliation(s)
- T F Cloughesy
- Department of Neurology, UCLA School of Medicine, USA
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42
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Hsueh WA, Law RE. Pharmacological treatment and mechanisms of insulin resistance. Impact on vascular smooth muscle cells, blood pressure, and lipids. Ann N Y Acad Sci 1997; 827:170-7. [PMID: 9329752 DOI: 10.1111/j.1749-6632.1997.tb51832.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- W A Hsueh
- Division of Endocrinology, Diabetes, and Hypertension, University of Southern California, School of Medicine, Los Angeles 90033, USA
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43
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Abstract
Angiotensin II (AII) plays a crucial role in controlling the proliferation and migration of vascular smooth muscle cells (VSMCs). The present study was undertaken to determine if troglitazone (Tro) has an effect on the G-protein coupled signaling through AII type I (AT-1) receptors in cultured rat aortic VSMCs. AII-induced MAP kinase activation was inhibited 67.9% by Tro. AII-induced DNA synthesis and migration was completely inhibited by Tro or by the AT-1 receptor blocker irbesartan. The present study demonstrates that troglitazone inhibits AII-induced DNA synthesis, migration and MAP kinase activation in VSMCs which are important molecular events for the development of neointimal hyperplasia and atherosclerosis.
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Affiliation(s)
- K Graf
- University of Southern California, School of Medicine, Department of Medicine, Los Angeles 90033, USA.
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44
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Graf K, Xi XP, Yang D, Fleck E, Hsueh WA, Law RE. Mitogen-activated protein kinase activation is involved in platelet-derived growth factor-directed migration by vascular smooth muscle cells. Hypertension 1997; 29:334-9. [PMID: 9039124 DOI: 10.1161/01.hyp.29.1.334] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Migration of vascular smooth muscle cells (VSMCs) is a crucial response to vascular injury resulting in neointima formation and atherosclerosis. Platelet-derived growth factor (PDGF-BB) functions as a potent chemoattractant for VSMCs and enhances these pathologies in the vasculature. However, little is known about the intracellular pathways that mediate VSMC migration. In the present study, we investigated the role of mitogen-activated protein kinase (MAPK) activation in this function, since PDGF-BB as well as other growth factors activate this pathway. Using an in-gel kinase assay, we observed that PD 98059 an inhibitor of MEK that activates MAP kinase, inhibited PDGF-BB-induced activation of ERK-1 and ERK-2 in cultured rat aortic smooth muscle cells in a concentration-dependent manner. In contrast, PDGF-mediated activation of intracellular calcium release was not affected by PD 98059. The chemotactic response of both rat aortic smooth muscle cells (RASMCs) and human umbilical vein smooth muscle cells (HUSMCs) toward PDGF-BB (10 ng/mL) was significantly reduced by PD 98059 (10 mumol/L) to 41.7 +/- 7.1% in RASMCs (P < .01) and to 47.2 +/- 5.3% in HUSMCs (P < .01). Similar inhibition was seen at 30 mumol/L, less at 1 mumol/L. To further confirm the specificity of these results implicating the MAPK pathway, an antisense oligodeoxynucleotide (ODN) directed against the initiation translation site of rat ERK-1 and ERK-2 mRNA was used to suppress MAP kinase synthesis and function in rat VSMCs. Liposomal transfection with 0.4 mumol/L antisense ODN reduced ERK-1 and ERK-2 protein by 65% (P < .01) after 48 hours. The chemotactic response to PDGF-BB (10 ng/mL) was reduced by 75% (P < .01) in rat VSMCs transfected with the same antisense ODN concentration. Sense and scrambled control ODNs (0.4 mumol/L) did not affect ERK-1 and ERK-2 protein concentrations or chemotaxis of VSMCs induced by PDGF-BB. These experiments provide the first evidence that activation of MAPK is a critical event in PDGF-mediated signal transduction regulating VSMC migration.
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Affiliation(s)
- K Graf
- University of Southern California, Los Angeles, USA.
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45
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Law RE, Meehan WP, Xi XP, Graf K, Wuthrich DA, Coats W, Faxon D, Hsueh WA. Troglitazone inhibits vascular smooth muscle cell growth and intimal hyperplasia. J Clin Invest 1996; 98:1897-905. [PMID: 8878442 PMCID: PMC507630 DOI: 10.1172/jci118991] [Citation(s) in RCA: 376] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Vascular smooth muscle cell (VSMC) proliferation and migration are responses to arterial injury that are highly important to the processes of restenosis and atherosclerosis. In the arterial balloon injury model in the rat, platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) are induced in the vessel wall and regulate these VSMC activities. Novel insulin sensitizing agents, thiazolidinediones, have been demonstrated to inhibit insulin and epidermal growth factor-induced growth of VSMCs. We hypothesized that these agents might also inhibit the effect of PDGF and bFGF on cultured VSMCs and intimal hyperplasia in vivo. Troglitazone (1 microM), a member of the thiazolidinedione class, produced a near complete inhibition of both bFGF-induced DNA synthesis as measured by bromodeoxyuridine incorporation (6.5+/-3.9 vs. 17.6+/-4.3% cells labeled, P < 0.05) and c-fos induction. This effect was associated with an inhibition (by 73+/-4%, P < 0.01) by troglitazone of the transactivation of the serum response element, which regulates c-fos expression. Inhibition of c-fos induction by troglitazone appeared to occur via a blockade of the MAP kinase pathway at a point downstream of MAP kinase activation by MAP kinase kinase. At this dose, troglitazone also inhibited PDGF-BB-directed migration of VSMC (by 70+/-6%, P < 0.01). These in vitro effects were operative in vivo. Quantitative image analysis revealed that troglitazone-treated rats had 62% (P < 0.001) less neointima/media area ratio 14 d after balloon injury of the aorta compared with injured rats that received no troglitazone. These results suggest troglitazone is a potent inhibitor of VSMC proliferation and migration and, thus, may be a useful agent to prevent restenosis and possibly atherosclerosis.
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Affiliation(s)
- R E Law
- University of Southern California School of Medicine, Department of Medicine, Los Angeles 90033, USA
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46
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Anderson PW, Zhang XY, Tian J, Correale JD, Xi XP, Yang D, Graf K, Law RE, Hsueh WA. Insulin and angiotensin II are additive in stimulating TGF-beta 1 and matrix mRNAs in mesangial cells. Kidney Int 1996; 50:745-53. [PMID: 8872947 DOI: 10.1038/ki.1996.372] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Angiotensin II (Ang II) and insulin are implicated in the mesangial cell hypertrophy and excessive accumulation of mesangial matrix seen in glomerulosclerosis. Therefore, the effects of Ang II with and without insulin on mRNA levels of several important extracellular matrix genes and transforming growth factor beta-1 (TGF-beta 1) were examined. Ang II alone (1 microM) added to quiescent, murine mesangial cells in serum-free, insulin-free media slightly but not significantly increased TGF-beta 1, fibronectin, collagen I, collagen IV and laminin message levels. The slight elevations in message expression were reversed by losartan, suggesting that these modest effects are mediated by the AT-1 receptor. Ang II alone also had no significant effects on TGF-beta 1 and extracellular matrix message levels in quiescent rat mesangial cells. In contrast, significant increases in mRNA for collagen 1 (6-fold), collagen IV (4-fold), fibronectin 1 (4-fold) and TGF-beta 1 (2-fold) were seen with insulin alone (10(-6)M) in rat mesangial cells, and a dose-response effect could be demonstrated for insulin (10(-9) to 10(-6)M). Ang II plus insulin further significantly increased collagen I (9-fold), collagen IV (9-fold), fibronectin 1 (5-fold) and TGF-beta 1 (3-fold) message expression. These effects were partially reversed in the presence of losartan. The Northern analyses were supported by measurements of active and total TGF-beta 1 activity (pg/ml/ 5 x 10(6) cells): 1145 +/- 76 and 1960 +/- 199, serum free control; 1121 +/- 92 and 1932 +/- 214, Ang II (10(-6)M); 4589 +/- 103 (P < 0.001 vs. control) and 11071 +/- 1952 (P < 0.01 vs. control), insulin (10(-6)M); and 6881 +/- 183 (P < 0.001 vs. control) and 16626 +/- 1435 (P < 0.01 vs. control), insulin plus Ang II. These results suggest that insulin, itself, significantly increases TGF-beta 1 and extracellular matrix gene expression in rat mesangial cells. Ang II alone has modest effects, while Ang II and insulin have additive effects. To explain the mechanism of these additive effects, we investigated the action of Ang II on insulin signaling and the effect of insulin on Ang II AT1 receptor mRNA expression. Ang II did not enhance insulin-induced insulin receptor substrate-1 (IRS-1) phosporylation or phosphatidylinositol3 (PI-3) kinase activity, but did enhance insulin-induced mitogen activated protein (MAP) kinase activity. Insulin increased message levels of AT1 receptor by twofold. These results suggest that enhancement of MAP kinase activity and AT1 receptor regulation by insulin may contribute to the additive effects of insulin and Ang II in mesangial cells.
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Affiliation(s)
- P W Anderson
- Department of Medicine, University Southern California Medical School, Los Angeles, USA
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47
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Hamilton HB, Hinton DR, Law RE, Gopalakrishna R, Su YZ, Chen ZH, Weiss MH, Couldwell WT. Inhibition of cellular growth and induction of apoptosis in pituitary adenoma cell lines by the protein kinase C inhibitor hypericin: potential therapeutic application. J Neurosurg 1996; 85:329-34. [PMID: 8755764 DOI: 10.3171/jns.1996.85.2.0329] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Protein kinase C (PKC) is an enzyme involved in the regulation of cellular growth, proliferation, and differentiation in a number of tissues including the anterior pituitary, in which it is also believed to play a role in hormone secretion. Protein kinase C activity and expression have been found to be greater in adenomatous pituitary cells than in normal human and rat pituitary cells and higher in invasive pituitary tumor cells than in noninvasive ones. Inhibition of PKC activity has been shown in a variety of tumor cells to inhibit growth in a dose-related fashion. The purpose of the current study was to determine whether hypericin, a potent inhibitor of PKC activity that may be administered clinically, alters the growth and proliferation in established pituitary adenoma lines and to determine if inhibition of PKC activity induces apoptosis, as reported in some other tumor cell types. Two established pituitary adenoma cell lines, AtT-20 and GH4C1, were treated with hypericin in tissue culture for defined periods following passage. Inhibition of growth was found to be dose dependent in all three cell lines in low micromolar concentrations of hypericin, as determined by viable cell counts, methylthiotetrazole assay, and [3H]thymidine uptake studies. Concentrations of hypericin as low as 100 nM also induced apoptosis in these established lines, whereas treatment of normal human fibroblasts with a concentration of 10 microM failed to induce apoptosis. The potential use of hypericin in the therapy of pituitary adenomas warrants additional in vitro investigations with the aim of later moving toward therapeutic trials in selected patients in whom surgical or medical therapy has failed.
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Affiliation(s)
- H B Hamilton
- Department of Neurosurgery, University of Southern California School of Medicine, Los Angeles, USA
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48
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Zhang W, Anker L, Law RE, Hinton DR, Gopalakrishna R, Pu Q, Gundimeda U, Weiss MH, Couldwell WT. Enhancement of radiosensitivity in human malignant glioma cells by hypericin in vitro. Clin Cancer Res 1996; 2:843-6. [PMID: 9816239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Hypericin, an antidepressant and antiviral agent being evaluated in phase I and II trials for patients with HIV infection, is known to be a potent protein kinase C inhibitor. We have investigated its effects on cellular response to radiation via a tetrazolium-formazan cell growth rate assay using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and clonogenic assay in three human glioblastoma cell lines, U87-MG, A-172, and T98G, and a low-passage malignant glioma culture, 93-492. At a concentration of 5 microM, hypericin inhibited these cells slightly but caused significant radiosensitization (e.g., the cell survival rate after the radiation treatment was 50.2 and 26.0% in cells treated with 6 Gy and 6 Gy plus 5 microM hypericin in U87-MG cells, respectively; P = 0.0285). Hypericin also enhanced the radiosensitivity significantly in the low-passage glioma 93-492 cells. These findings suggest that hypericin represents a potential new agent in combination with radiation therapy of malignant gliomas.
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Affiliation(s)
- W Zhang
- Departments of Neurological Surgery, robiolology, and Radiation Oncology, University of Southern California School of Medicine, Los Angeles, California 90033, USA
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49
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Couldwell WT, Hinton DR, Surnock AA, DeGiorgio CM, Weiner LP, Apuzzo ML, Masri L, Law RE, Weiss MH. Treatment of recurrent malignant gliomas with chronic oral high-dose tamoxifen. Clin Cancer Res 1996; 2:619-22. [PMID: 9816211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The present clinical trial was undertaken to assess the clinical safety and possible efficacy of administering tamoxifen to patients with recurrent malignant glial tumors at dosages calculated to achieve levels sufficient to inhibit protein kinase C within the tumor cells. Chronic p.o. tamoxifen was administered in very high dosages to 32 patients (20 males and 12 females; age range, 26-75 years; mean, 49 years) with histologically verified malignant glioma [anaplastic astrocytoma (12 patients) or glioblastoma multiforme (20 patients)] who had demonstrated clinical and radiographical progression or recurrence following external beam radiation therapy (and additional chemotherapy in 11; immunotherapy in 2). The dosage of tamoxifen administered was 200 mg/day to males and 160 mg/day to females given in a twice daily schedule. Clinical and radiographical (defined as a greater than 50% decrease in volume of the enhancing lesion volume on magnetic resonance imaging and a decrease in metabolic activity on serial positron emission tomographic scans) response was noted in 8 patients (25%; 4/12 with anaplastic astrocytoma and 4/20 glioblastoma multiforme), with an additional 6 patients (19%) exhibiting stabilization of disease with minimal side effects. Median survival from the time of diagnosis for the entire cohort was 24 months (104 weeks), for the anaplastic astrocytoma group 42.5 months (185 weeks), and for the glioblastoma group 17.4 months (75.5 weeks). From the initiation of tamoxifen, median survival for the entire cohort was 10.1 months (44 weeks), for the anaplastic astrocytoma group 16 months (69 weeks), and for the glioblastoma group 7.2 months (31 weeks). The mean length of follow-up of all patients after initiating tamoxifen was 16 months (69 weeks), while the mean length of follow-up of alive patients is 22.6 months (98 weeks) (range up to 51 months). These data suggest that a subgroup of patients with malignant gliomas respond or stabilize with chronic high-dose tamoxifen therapy. This therapy may represent an alternative or adjuvant to existing chemotherapies for these tumors; further clinical trials are warranted.
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Affiliation(s)
- W T Couldwell
- Departments of Neurological Surgery, Division of Biometry, University of Southern California School of Medicine, Los Angeles, California 90033, USA
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50
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Couldwell WT, Law RE, Hinton DR, Gopalakrishna R, Yong VW, Weiss MH. Protein kinase C and growth regulation of pituitary adenomas. Acta Neurochir Suppl 1996; 65:22-6. [PMID: 8738488 DOI: 10.1007/978-3-7091-9450-8_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The present study was undertaken to explore the role of the Protein Kinase C (PKC) signal transduction system in growth regulation of pituitary adenomas. Primary tumor cultures were plated from fresh surgical tumor specimens. The PKC inhibitors Staurosporine and Tamoxifen were added at varying dosages to the cell cultures. Measurements of cell proliferation were performed by [3H]-thymidine uptake and the [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] (MTT) assay. After a 48 h treatment period, both [3H]-thymidine uptake and absorbance on the MTT assay decreased in a dose-related manner in both the staurosporine and tamoxifen-treated cultures (IC50 of 10 nM and 30 microM respectively). Direct measurement of PKC activity using an in vitro assay revealed very high activity (range of 1465-5708 pmol/min/mg protein; within the range previously published for malignant glioma specimens) in 12 frozen specimens of pituitary adenomas (9 nonfunctional adenomas, 1 prolactinoma, 1 gonadotrophin-secreting and 1 corticotroph-secreting adenoma). In contrast, PKC activity measured in normal adenohypophysis was comparatively very low. These data indicate that pituitary adenoma cells display high PKC activity and are sensitive to growth inhibition by PKC inhibitors. These data suggest a role for the PKC system in regulating pituitary tumor growth, which may have implications for future therapy of these tumors.
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Affiliation(s)
- W T Couldwell
- Department of Neurological Surgery, University of Southern California School of Medicine, Los Angeles, USA
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