Activated protein C stimulates expression of angiogenic factors in human skin cells, angiogenesis in the chick embryo and cutaneous wound healing in rodents

Activated protein C (APC) is a serine protease that plays a central role in physiological anticoagulation, and has more recently been shown to be a potent anti-inflammatory mediator. We show here that APC upregulates the angiogenic promoters, vascular endothelial growth factor (VEGF), monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8) or matrix metalloproteinase-2 (MMP-2) in cultured human skin fibroblasts (HF), keratinocytes (HK) or umbilical vein endothelial cells (HUVE). In the chick embryo chorio-allantoic membrane assay, APC promoted angiogenesis. In a full-thickness rat skin healing model, a single topical application of APC enhanced wound healing compared to saline control. In summary, our results demonstrate that APC promotes cutaneous wound healing at least partly by stimulation of angiogenesis.

Myocardial Gene Expression of Angiogenic Factors in Human Chronic Ischemic Myocardium: Influence of Acute Ischemia/Cardioplegia and Reperfusion

OBJECTIVE

Angiogenic therapies in animals have demonstrated the development of new blood vessels within ischemic myocardium. However, results from clinical protein and gene angiogenic trials have been less impressive. The present study aimed to investigate the expression of angiogenic genes in human chronic ischemic myocardium and the influence of acute ischemia/cardioplegia and reperfusion on their expression.

METHODS

Myocardial biopsies were taken from chronic ischemic and nonischemic myocardium in 15 patients with stable angina pectoris during coronary bypass surgery. Tissue samples were evaluated by oligonucleotide microarray and quantitative real-time PCR for the expression of angiogenic factors.

RESULTS

There was identical baseline expression of VEGF-A and VEGF-C mRNA in chronic ischemic myocardium compared with nonischemic myocardium. Reperfusion increased the gene expression of VEGF-A and VEGF-C mRNA both in nonischemic and ischemic myocardium. VEGF-A protein was detected mainly in the extracellular matrix around the cardiomyocytes in ischemic myocardium.

CONCLUSION

These data suggest that the nonconclusive VEGF gene therapy trials chronic coronary artery disease was not due to a preexisting upregulation of VEGF in chronic ischemic myocardium. There might be room for further therapeutic angiogenesis in chronic ischemic myocardium.

Identification of genes modulated in rheumatoid arthritis using complementary DNA microarray analysis of lymphoblastoid B cell lines from disease-discordant monozygotic twins

OBJECTIVE

To identify disease-specific gene expression profiles in patients with rheumatoid arthritis (RA), using complementary DNA (cDNA) microarray analyses on lymphoblastoid B cell lines (LCLs) derived from RA-discordant monozygotic (MZ) twins.

METHODS

The cDNA was prepared from LCLs derived from the peripheral blood of 11 pairs of RA-discordant MZ twins. The RA twin cDNA was labeled with cy5 fluorescent dye, and the cDNA of the healthy co-twin was labeled with cy3. To determine relative expression profiles, cDNA from each twin pair was combined and hybridized on 20,000-element microarray chips. Immunohistochemistry and real-time polymerase chain reaction were used to detect the expression of selected gene products in synovial tissue from patients with RA compared with patients with osteoarthritis and normal healthy controls.

RESULTS

In RA twin LCLs compared with healthy co-twin LCLs, 1,163 transcripts were significantly differentially expressed. Of these, 747 were overexpressed and 416 were underexpressed. Gene ontology analysis revealed many genes known to play a role in apoptosis, angiogenesis, proteolysis, and signaling. The 3 most significantly overexpressed genes were laeverin (a novel enzyme with sequence homology to CD13), 11beta-hydroxysteroid dehydrogenase type 2 (a steroid pathway enzyme), and cysteine-rich, angiogenic inducer 61 (a known angiogenic factor). The products of these genes, heretofore uncharacterized in RA, were all abundantly expressed in RA synovial tissues.

CONCLUSION

Microarray cDNA analysis of peripheral blood-derived LCLs from well-controlled patient populations is a useful tool to detect RA-relevant genes and could help in identifying novel therapeutic targets.

Graves' disease and Hashimoto's thyroiditis in monozygotic twins: case study as well as transcriptomic and immunohistological analysis of thyroid tissues

OBJECTIVE

To report on the rare simultaneous occurrence of Graves' disease (GD) and Hashimoto's thyroiditis (HT) in monozygotic twins.

DESIGN

We compared the pattern of thyroid tissue-derived cDNAs to gain insight into previous and ongoing immune destruction and reconstruction processes using microarrays. The results were confirmed by immunohistology and real-time PCR.

RESULTS

Destruction of thyroid tissue in HT reduced levels of thyrocyte-related cDNAs and cDNAs encoding extracellular matrix components, but increased levels of proteases involved in extracellular matrix degradation compared with GD. Lymphocytic infiltrates forming ectopic follicles replaced the thyroid tissue almost completely in HT. Thus, lymphocyte-related cDNA levels were higher in HT than in GD. The same was true for many chemokines and their receptors, which not only enable migration towards the thyroid but also maintain the lymphocytic infiltrate. HT also showed increased levels of cDNAs encoding molecules related to apoptosis than did GD. Surprisingly, the Th1- and Th2-specific cytokine profiles suggested for HT and GD respectively could not be confirmed. cDNAs encoding factors and receptors involved in angiogenesis were increased in GD compared with HT.

CONCLUSIONS

Comparison of gene expression reflects the cellular differences between the two types of autoimmune thyroid disease in twins with identical genetic and similar environmental background.

Ultraviolet Radiation Attenuates Thrombospondin 1 Expression via PI3K-Akt Activation in Human Keratinocytes

Thrombospondin 1 (TSP1) is an extracellular glycoprotein and a recognized inhibitor of angiogenesis. Recent studies have demonstrated that UV radiation induces an angiogenic switch, by which it alters the balance between pro- and anti-angiogenic factors in the skin. Here we describe the effects of acute UV exposure on TSP1 expression in human skin epidermis, primary keratinocytes and the epidermal cell line HaCaT. We found that protein and mRNA expressions of TSP1 are significantly reduced in human skin in vivo and in keratinocytes in vitro by a single UV exposure. In human skin and keratinocytes, UV exposure induced the phosphorylation of Akt, a downstream target of the PI3K pathways. Specific inhibitors of PI3K, wortmannin and LY294002, completely blocked Akt activation and UV-induced TSP1 downregulation in keratinocytes. We showed that a specific Akt phosphorylation inhibitor and small interfering RNA-mediated Akt depletion were also blocked by UV-induced TSP1 downregulation in keratinocytes. In conclusion, our findings demonstrate that acute UV exposure downregulates TSP1 expression via PI3K-Akt activation in human keratinocytes. These novel findings may help us understand the regulatory mechanisms of UV-induced skin angiogenesis.

Diagnostic and prognostic value of angiogenesis-modulating genes in malignant thyroid neoplasms

BACKGROUND

Angiogenesis is an essential biologic event in the pathogenesis of human malignancies. We postulated that expression analysis of genes that modulate angiogenesis would identify differentially expressed genes that would help to distinguish benign from malignant thyroid neoplasms and serve as markers of aggressive differentiated thyroid cancer.

METHODS

A complementary DNA (cDNA) array with 96 genes that modulate angiogenesis was used to identify differentially expressed genes (2-fold higher or lower) in malignant versus benign thyroid neoplasms. Real-time quantitative polymerase chain reaction was used to confirm cDNA array expression data in 123 patients (4 normal thyroid, 26 hyperplastic nodules, 27 follicular adenomas, 23 follicular cancers, 18 follicular variant of papillary cancers, 25 papillary cancers).

RESULTS

Twenty-two genes were upregulated in malignant thyroid neoplasms by cDNA array analysis, but only 13 genes had higher messenger RNA (mRNA) expression levels in malignant than in benign thyroid neoplasms by real-time quantitative polymerase chain reaction (P < or = .04). Of the 13 differentially expressed genes, the combined use of angiopoietin 2 (ANGPT2) and tissue inhibitor of metalloproteinase 1 (TIMP1) mRNA expression levels was best for distinguishing malignant from benign thyroid neoplasms, with a sensitivity of 90%, specificity of 85%, positive predictive value of 75%, and negative predictive value of 94%. Epidermal growth factor receptor and ephrin B2 mRNA expression was elevated in higher TNM stage neoplasms and in patients with high-risk AMES (Age, distant Metastasis, Extrathyroidal invasion, and tumor Size) differentiated thyroid cancers (P < or = .005).

CONCLUSIONS

Angiopoietin 2 and tissue inhibitor of metalloproteinase 1 are diagnostic markers of malignant thyroid nodules and could improve the diagnostic accuracy of FNA biopsy. Epidermal growth factor receptor and ephrin B2 are markers of aggressive differentiated thyroid cancer.

Effect of aging on expression of angiogenesis-related factors in mouse skeletal muscle

The molecular mechanisms by which capillary supply is maintained with advancing age remain to be elucidated. To help clarify these mechanisms, we investigated the gene expression levels of angiogenesis-related factors in young (2.5-month-old), adult (6-month-old), and old (22-month-old) mice. To assess the capillary supply, the capillary endothelium in frozen transverse sections was identified by staining for alkaline phosphatase. The mRNA levels for angiogenesis-related factors were analyzed using real-time RT-PCR. The capillary supply to individual muscle fibers, assessed as the number of capillaries around a muscle fiber, did not change with advancing age. Real-time RT-PCR analysis showed that (1) the level of mRNA for VEGF was lower in old animals than young animals; (2) the mRNA levels of Flt-1 and neuropilin-1 are lower in old animals than young animals, while that of KDR/Flk-1 remained unchanged with advancing age; and (3) the levels of mRNA for angiopoietin-1 and -2 remained unchanged, while the mRNA for Tie-2 was lower in old animals than young animals. These findings suggest that capillary supply is maintained irrespective of the down-regulation of several angiogenesis-related factors and that old animals possess the minimum levels of maintenance and reparative abilities needed to preserve the capillary supply.

Transcriptional expression of the genes implicated in angiogenesis and tumor invasion in cervical carcinomas

OBJECTIVE

Co-expression patterns of the genes implicated in angiogenesis and tumor invasion in cervical carcinoma cells were investigated together with invasive activity of tumor cells. Transcript levels of those genes were also compared between tumor cells and normal cervical tissues.

METHODS

Real-time quantitative RT-PCR analysis was conducted on selected 11 genes (total VEGF-A, VEGF(121), VEGF(165), VEGF(189), VEGF-B, C and D, bFGF, dThdPase, MMP-2 and uPA) using 11 cervical carcinoma cell lines and 14 normal cervical tissues. Protein expression of VEGF-C and MMP-2 and invasive activity of tumor cells were evaluated for each cell line by sandwich ELISA and haptoinvasion assay, respectively.

RESULTS

Gene co-expression analysis revealed the significant correlation between angiogenic factors and proteinases in malignant but not in normal cervical samples. Gene or protein expression levels of VEGF-C and MMP-2 were well correlated with the number of invaded tumor cells. VEGF-A splicing variants were increased in malignant compared to normal cervical samples but not associated with the invasive activity of the cells.

CONCLUSION

VEGF-C and MMP-2 were closely related to invasive phenotype of tumor cells, whereas VEGF-A isoforms were considered to be involved in cervical carcinogenesis.

Hepatocyte growth factor/scatter factor differentially regulates expression of proangiogenic factors through Egr-1 in head and neck squamous cell carcinoma

Hepatocyte growth factor/scatter factor (HGF) and the angiogenesis factors platelet-derived growth factors (PDGF), vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8) are found in elevated concentrations in serum or tumor tissue of patients with head and neck squamous cell carcinomas (HNSCC), suggesting these factors may be coregulated. A cDNA microarray analysis for HGF-inducible genes revealed that HGF also modulates PDGFA expression, a gene recently shown to be inducible by the transcription factor, early growth response-1 (Egr-1). In the present study, we investigated the potential role of HGF-induced Egr-1 in expression of PDGF, VEGF, and IL-8. HGF induced expression of all three factors and Egr-1 expression and DNA-binding activity. The analysis of promoter sequences showed putative Egr-1 binding sites in the PDGFA or VEGF but not in the IL-8 promoter, and HGF-induced Egr-1-binding activity was confirmed by chromatin immunoprecipitation (ChIP) assay. The maximal basal and HGF-induced promoter activity for the PDGFA gene existed within -630 bp of the promoter region, and overexpression of Egr-1 significantly increased such activity. Consistent with this, expression of PDGFA and VEGF but not IL-8 showed corresponding differences with Egr-1 expression in HNSCC tumor specimens and were strongly suppressed by transfection of Egr-1-antisense or small interference RNA (siRNA) oligonucleotides. HGF-induced expression of Egr-1, PDGFA, and VEGF was suppressed by pharmacologic and siRNA inhibitors of mitogen-activated protein kinase kinase 1/2 (MEK1/2) and protein kinase C (PKC) pathways. We conclude that the HGF-induced activation of transcription factor Egr-1 by MEK1/2- and PKC-dependent mechanisms differentially contributes to expression of PDGF and VEGF, which are important angiogenesis factors and targets for HNSCC therapy.

Antiangiogenic activity of BAI1 in vivo: implications for gene therapy of human glioblastomas

Glioblastomas are the most common primary brain tumors in adults. These tumors exhibit a high degree of vascularization, and malignant progression from astrocytoma to glioblastoma is often accompanied by increased angiogenesis and the upregulation of vascular endothelial growth factor and its receptors. In this study, we investigated the in vivo antiangiogenic and antitumor effects of brain-specific angiogenesis inhibitor 1 (BAI1) using human glioblastoma cell lines. Glioblastoma cells were transduced with an adenoviral vector encoding BAI1 (AdBAI1), and Northern and Western blot analyses, respectively, demonstrated BAI1 mRNA and protein expression in the transduced tumor cells. Using an in vivo neovascularization assay, we found that angiogenesis surrounding AdBAI1-transduced glioblastoma cells transplanted into transparent skinfold chambers of SCID mice was significantly impaired compared to control treated cells. Additionally, in vivo inoculation with AdBAI1 of established subcutaneous or intracerebral transplanted tumors significantly impaired tumor growth and promoted increased mouse survival. Morphologically, the tumors exhibited signs of impaired angiogenesis, such as extensive necrosis and reduced intratumoral vascular density. Taken together, these data strongly indicate that BAI1 may be an excellent gene therapy candidate for the treatment of brain tumors, especially human glioblastomas.

Soluble factors released by endothelial progenitor cells promote migration of endothelial cells and cardiac resident progenitor cells

Circulating endothelial progenitor cells (EPC) are incorporated into newly formed capillaries, enhance neovascularization after hind limb ischemia and improve cardiac function after ischemic injury. Incorporated progenitor cells may also promote neovascularization and cardiac regeneration by releasing factors, which act in a paracrine manner to support local angiogenesis and mobilize tissue residing progenitor cells. Therefore, we analyzed the expression profile of cytokines in human peripheral blood-derived EPC as opposed to human umbilical vein endothelial cells (HUVEC), human microvascular endothelial cells (HMVEC), and CD14(+) monocytes by microarray technology. A gene tree analysis revealed a distinct expression pattern of angiogenic growth factors in EPC, mature endothelial cells, and CD14(+) monocytes. VEGF-A, VEGF-B, SDF-1, and IGF-1 mRNA levels were higher in EPC as compared to HUVEC or HMVEC. The enhanced mRNA expression was paralleled by a significant release of VEGF, SDF-1, and IGF-1 protein into the cell culture supernatant of EPC. Moreover, immunohistological analysis of ischemic limbs from nude rats revealed that VEGF is also released from recruited human EPC in vivo. As a functional consequence, conditioned medium of EPC induced a strong migratory response of mature endothelial cells, which was significantly inhibited by VEGF and SDF-1 neutralizing antibodies. Finally, conditioned medium of EPC significantly stimulated the migration of cardiac resident c-kit(+) progenitor cells in vitro. Taken together, EPC exhibit a high expression of angiogenic growth factors, which enhanced migration of mature endothelial cells and tissue resident cardiac progenitor cells. In addition to the physical contribution of EPC to newly formed vessels, the enhanced expression of cytokines may be a supportive mechanism to improve blood vessel formation and cardiac regeneration after cell therapy.

Tumor hypoxia and cancer progression

Aerobic life consumes oxygen for efficient production of high energy compounds. The ability to sense and respond to changes in oxygen partial pressure represents a fundamental property to assure the cellular oxygen supply to be within a narrow range that balances the risks of oxidative damage vs. oxygen deficiency. The discovery of hypoxia-inducible factor-1 (HIF-1) allowed the identification of molecular mechanisms by which changes in oxygenation are transduced to adequate intracellular adaptive responses. It became apparent that hypoxia can initiate cell demise by apoptosis/necrosis but also prevent cell death by provoking adaptive responses that, in turn, facilitate cell proliferation or angiogenesis, thus contributing to tumor progression. Considering that activation of HIF-1 provokes pro-survival as well as pro-death decisions under hypoxia, it will be crucial to understand decision making processes in regulating cell death, adaptation and chemoresistance. Likely, secondary stressors such as pH changes, i.e. acidosis, and the context of genetic alterations will shape the role of HIF-1 to affect susceptibility of cells to undergo hypoxia-induced cell death or to allow adaptation and progression towards malignancy. Understanding the mechanisms by which HIF-1 affects the expression and/or function of key apoptotic regulators such as Bcl-2 family members or p53 will help to uncover how HIF-1 induces cell death and the manner in which cells can overcome such signals and thus determine which of its Janus faces prevail.

Biomedicine and diseases: the Klippel-Trenaunay syndrome, vascular anomalies and vascular morphogenesis

Vascular morphogenesis is a vital process for embryonic development, normal physiologic conditions (e.g. wound healing) and pathological processes (e.g. atherosclerosis, cancer). Genetic studies of vascular anomalies have led to identification of critical genes involved in vascular morphogenesis. A susceptibility gene, VG5Q (formally named AGGF1), was cloned for Klippel-Trenaunay syndrome (KTS). AGGF1 encodes a potent angiogenic factor, and KTS-associated mutations enhance angiogenic activity of AGGF1, defining 'increased angiogenesis' as one molecular mechanism for the pathogenesis of KTS. Similar studies have identified other genes involved in vascular anomalies as important genes for vascular morphogenesis, including TIE2, VEGFR-3, RASA1, KRIT1, MGC4607, PDCD10, glomulin, FOXC2, NEMO, SOX18, ENG, ACVRLK1, MADH4, NDP, TIMP3, Notch3, COL3A1 and PTEN. Future studies of vascular anomaly genes will provide insights into the molecular mechanisms for vascular morphogenesis, and may lead to the development of therapeutic strategies for treating these and other angiogenesis-related diseases, including coronary artery disease and cancer.

Qualitative and quantitative analysis of angiogenetic factors in transitional cell bladder carcinoma: relationship with clinical course at 10 years follow-up

Many authors have shown that tumor hypoxia exerts its own influence on malignant progression by inducing angiogenetic factors and new blood vessels inside and around the tumor. This event usually suggests a poor prognosis and/or aggressive tumor behavior. The objective of the present study is to compare molecular analysis of angiogenetic factors with microvessel density (MVD) in bladder carcinoma. Twenty-nine consecutive patients underwent transurethral or open surgery for bladder tumors. Neoplastic tissue samples, normal-appearing bladder mucosa and blood samples were taken from each patient. All the tissues underwent mRNA extraction and Northern blot analysis, marked with specific probes for inducible nitric oxide sinthase (iNOS), cyclo-oxygenase-2 (cox-2), vascular endothelial growth factor (VEGF) and were evaluated by gel-electrophoresis. Microvessel density, a quantitative analysis for neoangiogenesis, was also evaluated by using CD31 immunohistochemical assay and compared with both molecular analysis and patient follow-up. Two follow-up for recurrence and/or progression were performed at 74 months and 10 years from surgery respectively. Pathological evaluation demonstrated the presence of superficial transitional cell carcinoma (sTCC) in 15 patients, while 14 had an invasive bladder tumor (iBT). At both 74 months and 10 years follow-up, all patients with lower MVD had a shorter survival time. No significant results were obtained by comparing disease progression or survival rate with VEGF, iNOS and COX-2 levels. A proportional increase of VEGF expression and MVD compared with poor prognosis was the expected outcome of our study. These results were disregarded at both the 1st and the 2nd follow-up. A strong association between MVD>20 and survival rate was noted both in sTCC (p=0.024) and iBT (p>0.001) patients. These results confirm that MVD could be considered a good prognostic factor. The angiogenetic cytokines overexpression found in control tissue samples of sTCC could have clinical significance, either as a macroscopically unidentified diffuse carcinogenetic process or the presence of a systemic immune-response against tumor cells.

Vasculostatin, a proteolytic fragment of brain angiogenesis inhibitor 1, is an antiangiogenic and antitumorigenic factor

Brain angiogenesis inhibitor 1 (BAI1) is a transmembrane protein with unknown function expressed primarily in normal but not tumoral brain. The finding of thrombospondin type 1 repeats in its extracellular domain suggested an antiangiogenic function, but the mechanisms by which a transmembrane receptor could inhibit angiogenesis remained unexplained. Here we demonstrate that BAI1 is proteolytically cleaved at a conserved G-protein-coupled receptor proteolytic cleavage site (GPS), releasing its 120 kDa extracellular domain. We named this secreted fragment Vasculostatin as it inhibited migration of endothelial cells in vitro and dramatically reduced in vivo angiogenesis. Both constitutive and doxycycline-induced expression of Vasculostatin elicited dose-dependent suppression of tumor growth and vascular density in mice, implicating Vasculostatin in the regulation of vascular homeostasis and tumor prevention. Generation of a soluble antiangiogenic factor by cleavage of a pre-existing transmembrane protein represents a novel mechanism for regulating vascular homeostasis and preventing tumorigenesis. Modulation of this cleavage or delivery of Vasculostatin may constitute novel treatment modalities for cancer and other diseases of aberrant angiogenesis, especially in the brain.

HOXA3 induces cell migration in endothelial and epithelial cells promoting angiogenesis and wound repair

Wound repair requires both the recruitment and coordination of numerous cell types including inflammatory cells, fibroblasts, endothelial and epithelial cells. Each cell type has a distinct set of cell behavior such as formation of granulation tissue and basement membrane, migration, proliferation and redifferentiation. These processes are dependent on cell-cell and cell-ECM signaling, intracellular signal transduction cascades, and ultimately, changes in gene transcription. We have investigated the role of the transcription factor HOXA3 in wound repair and angiogenesis. Here we show that HOXA3 increases endothelial cell migration, induces angiogenesis in vivo, and leads to increased expression of the matrix metalloproteinase-14 (MMP-14) and urokinase-type plasminogen activator receptor (uPAR) genes in endothelial cells in culture and in vivo in response to injury. We find that HOXA3 gene expression is upregulated during wound healing in angiogenic endothelial cells and keratinocytes, and that HOXA3 is not induced in genetically diabetic mice that have impaired angiogenesis and wound repair. We demonstrate that gene transfer of HOXA3 into diabetic mouse wounds leads to dramatic improvements in both angiogenesis and wound closure. In addition, we show that HOXA3 promotes migration of endothelial cells and keratinocytes in a uPAR-dependent manner. Together these findings illustrate how the morphoregulatory protein, HOXA3 can facilitate tissue remodeling via coordinated changes in both epithelial and endothelial cell gene expression and behavior in adult tissues during wound repair.

Differential expression of pro- and antiangiogenic factors in mouse strain-dependent hypoxia-induced retinal neovascularization

Clinical observations suggest that genetic factors may influence heterogeneity of angiogenic responses in cardiovascular disease, proliferative diabetic retinopathy, and neoplasia. Experiments among mouse strains using a corneal micropocket assay indicate that extent of angiogenesis may be genetically determined. Here, we established the strain-dependence of hypoxia-induced retinal angiogenesis in multiple mouse strains which paralleled the rank order found for bFGF-induced corneal angiogenesis. Using quantitative real-time RT-PCR, strain-related gene expression differences in retina/choroid between C57BL/6J and 129S3/SvIM, inbred strains with relatively low and high levels of angiogenesis, respectively, after 0, 6, 12, 24, 48, and 96 h hypoxia were determined for vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2), angiogenic ligands potently induced by hypoxia, and for pigment epithelium-derived factor (PEDF) and thrombospondin-1 (TSP-1), endogenous broad-spectrum antiangiogenic factors. Indirect ELISA was used to correlate VEGF and PEDF protein levels with mRNA expression. At the onset of hypoxia, both PEDF and TSP-1 levels were increased over 15-fold and VEGF was increased over 10-fold compared to Ang-2 in both strains. At the onset of neovascularization (48 h), both VEGF and Ang-2 mRNA levels were increased in the more angiogenic 129S3/SvIM strain (P < 0.02), which was not observed among developmental control animals. PEDF expression was higher in the less angiogenic C57BL/6J strain at 6, 12, 24, and 96 h hypoxia (P < 0.03), while TSP-1 expression was higher in C57BL/6J throughout the entire time course of hypoxia (4 days) compared to 129S3/SvIM (P < 0.02). Among developmental control animals, PEDF and TSP-1 expression was also increased at P14 and P16 in C57BL/6J strain compared to 129S3/SvIM (P < 0.02). Strain-dependent expression of both pro- and antiangiogenic growth factors may determine heterogeneity in the angiogenic response and potentially, susceptibility to angiogenesis-dependent diseases.

Changes of vasoregulatory gene expression following hepatic ischemia/reperfusion and treatment with endothelin-A receptor blockade

The objective of this study was to investigate the effect of a specific endothelin-A receptor antagonist on mRNA expression of genes encoding vasoactive mediators and proinflammatory cytokines following complete vascular exclusion of the porcine liver. Fourteen adult German Landrace pigs were subjected to 120 minutes of warm hepatic ischemia by total vascular exclusion. The animals were divided into two groups: the control group received saline solution and the therapy group was given the selective endothelin-A receptor antagonist BSF 208075. Liver tissue samples were collected 1 hour after reperfusion and mRNA expression for preproendothelin-1, prointerleukin-1beta, prointerleukin- 6, pro-tumor necrosis factor-alpha and endothelial nitric oxide synthase was analyzed quantitatively using the TaqMan system. Additionally, immunohistochemical analysis using a semiquantitative score for endothelin-1 and endothelin-A receptor was performed. One hour after reperfusion, quantitative reverse transcriptase-polymerase chain reaction revealed significantly lower expression of preproendothelin-1, pro-tumor necrosis factor-alpha, and prointerleukin-6 in the therapy group compared to controls. Immunohistochemical analysis demonstrated significantly reduced endothelin-1 immunostaining after therapy. Treatment with the selective endothelin-A receptor antagonist exerts a protective effect on the microcirculation after liver ischemia and reperfusion. We were able to show that the endothelin-A receptor antagonist not only has effects on the expression of vasoactive genes, it also decreases gene expression of proinflammatory cytokines such as tumor necrosis factor-alpha and interleukin-6.

Influence of Maternal Nutrition on Messenger RNA Expression of Placental Angiogenic Factors and Their Receptors at Midgestation in Adolescent Sheep1

Previous studies have shown that placental growth and pregnancy outcome are severely compromised in adolescent ewes overnourished to promote rapid maternal growth. Using this paradigm, the aim of the present study was to investigate expression of the major angiogenic factors and their receptors in the placenta at the onset of the most rapid phase of fetal growth. Singleton pregnancies to a single sire were established by embryo transfer, and thereafter, adolescent dams were offered a high or moderate nutrient intake predicted to induce compromised or normal fetoplacental size at term, respectively. Ovine-specific oligonucleotide probe and primer sets for several angiogenic factors and their receptors were developed for quantitative real-time reverse transcription-polymerase chain reaction determination of placentome mRNA expression at Day 81 of gestation. Total placentome weight and fetal weight were equivalent in high- compared with moderate-intake groups at this stage of gestation. Placentome expression of the angiogenic factors, vascular endothelial growth factor, angiopoietins 1 and 2, and nitric oxide synthase 3, were reduced in overfed ewes. Similarly, level of expression of vascular endothelial growth factor/vascular permeability factor receptor (FLT1) was less in overfed ewes. Thus, in the adolescent, maternal overnutrition has a negative impact on midgestation placental angiogenic factor/ receptor expression. This may impact placental vascularity and explain why uteroplacental mass, blood flow, and nutrient uptake are compromised in late pregnancy, resulting in low-birth-weight offspring.

Expression of angiogenic factors is upregulated in DMBA-induced rat mammary pathologies

OBJECTIVE

In the 7,12-dimethylbenz[a]anthracene (DMBA) model of rat mammary carcinogenesis, microvascular density and angiogenic potential increase with progression from normal to invasive disease, but the mechanisms involved are unknown. Using RT-PCR, we determined the expression of angiogenic regulators in DMBA-induced intraductal hyperplasia (IDP), carcinoma in situ (CIS), invasive tumors (INV), as well as normal tissue.

METHODS

RT-PCR was performed on frozen tissue sections of each type of pathology for factors known to regulate angiogenesis in other systems.

RESULTS

MMP-2, MMP-9, uPA, PAI-1, IGF-2, BFGF, VEGF, ANG-1, IRS-1, and TSP-1 were significantly (p < or =0.05) upregulated in CIS and INV, whereas TIMP-1, ANG-2, MASPIN, IGF1-R and HBEGF were unchanged. IGF-1 was uniquely elevated in IDP. SPARC was downregulated in CIS. Inhibition of IGF-1R by the tyrphostin, AG1024, blocked endothelial tubulogenesis in vitro, confirming that IGF-1 functions as a regulator of angiogenesis.

CONCLUSIONS

These data support the involvement of specific angiogenic mediators in mammary tumor formation. Angiogenesis at different stages of tumorigenesis may be regulated by unique factors.

Lipid-mediated delivery of brain-specific angiogenesis inhibitor 1 gene reduces corneal neovascularization in an in vivo rabbit model

Corneal neovascularization, which occurs in many pathologic states of the cornea, reduces the visual acuity. Recently, we found that the extracellular region of brain-specific angiogenesis inhibitor 1 (BAI1-ECR) has antiproliferative activity through functional blocking of alpha(v)beta(5) integrin in endothelial cells. In this study, we investigated the effects of lipid-mediated subconjunctival injection of the BAI1-ECR gene on corneal angiogenesis induced by epithelial debridement by heptanol in the rabbit. When a pEGFP-BAI1-ECR plasmid was given subconjunctivally 1 week after epithelial debridement, green fluorescence was detected in the corneal stroma with expression persisting for 7 days. To test the effect of BAI1-ECR on neovascularization, rabbits were injected with the BAI1-ECR gene or empty vector two or three times at 1-week intervals beginning 1 week after debridement. When measured with biomicroscopy at 1 or 2 weeks after two weekly injections, BAI1-delivered eyes had significantly less neovascularized corneal area than vector-injected ones in both time periods. Similar microscopic results were obtained after three weekly injections of BAI1-ECR. In quantitative histological examination, the BAI1-receiving eyes showed significantly less neovascular area and number of vessels than vector-injected ones. Also, after two weekly injections, BAI1-delivered eyes had decreased neovascularized corneal area equivalent to that of anti-VEGF antibody-injected ones. These results indicate that BAI1-ECR gene delivery effectively reduces experimental corneal neovascularization and suggest that the BAI1-ECR protein can be used as an angiogenesis suppressor in the eye.