VEGFs, receptors and angiogenesis

Hypoxia regulation of expression and angiogenic effects of vasoactive intestinal peptide (VIP) and VIP receptors in LNCaP prostate cancer cells

Vascular endothelial growth factor (VEGF) is a main factor promoting neovascularization (angiogenesis) of solid tumours as prostate carcinoma. Hypoxia stimulates VEGF gene expression by activating the hypoxia-inducible factor-1 (HIF-1alpha). In the present study, the hypoxia-mimicking agent Ni(2+) induced vasoactive intestinal peptide (VIP) expression at both mRNA and peptide levels but it did not modify the expression of VIP receptors (VPAC(1), VPAC(2) and PAC(1) receptors) in androgen-dependent human LNCaP prostate cancer cells. VIP increased the mRNA levels of VPAC(1) and PAC(1) receptors whereas it decreased VPAC(2) receptor mRNA level. These features support that hypoxia up-regulation of VIP gene expression in prostatic carcinoma may lead to VIP regulation of the expression of its receptors by means of autocrine/paracrine mechanisms. Either VIP or hypoxia mimetics with Ni(2+) increased VEGF expression whereas both conditions together resulted in an additive response. It suggests two independent mechanisms for the observed pro-angiogenic activities of VIP and hypoxia. VIP did not stimulate HIF-1alpha mRNA expression but increased the translocation of HIF-1alpha from the cytosolic compartment to the cell nucleus. Moreover, VIP was unable to modify the expression of the HIF-1alpha inhibitor FIH-1 discarding the possibility of an indirect effect of VIP on HIF-1 transactivation.

Plasma levels of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) in familial Mediterranean fever

AIMS

To assess the levels of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) in patients with familial Mediterranean fever (FMF).

METHODS

Plasma levels of sVEGFR-1 were investigated in 33 FMF patients in an attack-free period (mean age 30.8 years; males/females 10/23), in 15 patients with acute FMF attack (mean age 32.7 years; males/females 7/8), and 19 healthy controls (mean age 32 years; males/females 11/8). Levels of sVEGFR-1 were also compared among patients who were receiving colchicine and those who were not.

RESULTS

Plasma sVEGFR-1 levels were 3.49+/-1.10, 3.53+/-1.02, and 0.37+/-0.28 ng/ml for FMF patients in the attack-free period, FMF patients with acute attack, and healthy controls, respectively. Plasma sVEGFR-1 levels were significantly higher in FMF patients with and without acute attack compared to the control group (p<0.05). sVEGFR-1 levels were not statistically significant between patients with acute attack and attack-free FMF patients (p>0.05). The plasma levels of sVEGFR-1 were also comparable in colchicine treated and untreated patients.

CONCLUSION

Our data suggest that sVEGFR-1 may have a role in the ongoing inflammatory cascade in FMF.

Drugs to suppress cough

Cough is an important defensive reflex of the airway and also a common symptom of respiratory disease. Cough after common respiratory virus infection is transient but is more persistent when associated with conditions such as asthma, rhinosinusitis, gastro-oesophageal reflux, chronic obstructive pulmonary disease and lung cancer. Persistent cough may be due to peripheral and/or central sensitisation of cough reflexes initiated by cough receptors, rapidly adapting receptors or nociceptors. Treatment directed at associated conditions such as asthma (with anti-inflammatories) and gastro-oesophageal reflux (with proton-pump inhibitors) improve cough. There remains a need to use drugs that suppress the neural activity of cough (termed nonspecific), as treatments directed at the clinical cause(s) of the underlying cough (termed specific) may not be effective. The most effective indirect antitussives are opioids such as morphine, codeine or pholcodeine, but they produce side effects such as drowsiness, nausea, constipation and physical dependence. Opioids such as kappa- and delta-receptor agonists, non-opioids such as nociceptin, neurokinin and bradykinin receptor antagonists, cannabinoids, vanilloid receptor-1 antagonists, blockers of Na+-dependent channels, and large conductance Ca2+-dependent K+-channel activators of afferent nerves may represent novel antitussives.

Prognostic significance of vascular endothelial growth factor D in gastric carcinoma

The angiogenic factor called vascular endothelial growth factor (VEGF)-D is a ligand for VEGF receptor-2 (VEGFR-2/KDR) and receptor-3 (VEGFR-3/Flt-4). It is implicated in the development of lymphatic vessels and promotion of lymphatic metastasis. The purpose of this study was to investigate the prognostic significance of VEGF-D expression in patients with gastric carcinoma. We assessed the expression of VEGF-D in gastric carcinoma by immunohistochemistry on 143 consecutive patients' stored sections and evaluated the lymphatic vessel count (LVC) in tumors using the novel selective lymphatic endothelium marker D2-40. VEGF-D expression was observed in 55 (39%) tumor sections. The expression of VEGF-D correlated significantly with tumor size, T of the TNM classification, lymphatic and venous system invasion, LVC, lymph node metastasis, M of TNM, and pTNM stage. Multivariate analysis indicated that VEGF-D expression was an independent prognostic factor for both relapse-free survival (RFS) and overall survival (OS). Our data indicate the involvement of VEGF-D in tumor progression via lymphoangiogenic pathways. Practically, VEGF-D expression can be useful for predicting RFS and OS in patients with gastric carcinoma.

Stable suppression of tumorigenicity by Pin1-targeted RNA interference in prostate cancer

PURPOSE

The peptidyl-prolyl isomrase Pin1 plays a catalytic role in oncogenesis in solid cancers, including prostate cancer. In the present study, we sought to determine the potential of Pin1-targeted gene silencing in inhibiting cellular growth and tumorigenicity in prostate cancer.

EXPERIMENTAL DESIGN

A retrovirus-mediated RNA interference targeting Pin1 was expressed in PC3 and LNCaP cells, and cell growth and several transformed properties were investigated.

RESULTS

The stable expression of Pin1-specific small interfering RNA constructs in PC3 and LNCaP cells significantly reduced cellular proliferation, colony formation, migration, and invasion but strongly enhanced the apoptotic response induced by serum depletion or treatment with anticancer agents. Furthermore, Pin1 depletion significantly suppressed tumorigenic potential in athymic mice, resulting in the inhibition of both tumor growth and angiogeneisis.

CONCLUSIONS

These results strongly suggest that Pin1 plays an important role not only in tumorigenesis but also in the maintenance of the transformed phenotype in prostate cancer cells. Hence, Pin1 may serve as a promising therapeutic target, particularly for recurrent prostate tumors.

Sanguiin H-6 blocks endothelial cell growth through inhibition of VEGF binding to VEGF receptor

The vascular endothelial growth factor (VEGF) plays a key role in angiogenesis, which is a process where new blood vessels develop from the endothelium of a pre-existing vasculature. VEGF exerts its activity by binding to its receptor tyrosine kinase, KDR/Flk-1, which is expressed on the surface of endothelial cells. A methanol extract and organic solvent (n-hexane, ethyl acetate, n-butanol, aqueous) fractions from Rubus coreanus were examined for their inhibitory effects on VEGF binding to the VEGF receptor. The methanol extract from the crude drug were found to significantly inhibit VEGF binding to the VEGF receptor (IC50 approximately = 27 microg/mL). Among the fractions examined, the aqueous fraction from the medicinal plant showed potent inhibitory effects against the binding of KDR/Flk-1-Fc to immobilized VEGF165 in a dose-dependent manner (IC50 approximately = 11 microg/mL). Sanguiin H-6 was isolated as an active principle from the aqueous fraction, and inhibited the binding of KDR/Flk-1-Fc to immobilized VEGF165 in a dose-dependent manner (IC50 approximately = 0.3 microg/mL). In addition, sanguiin H-6 efficiently blocked the VEGF-induced HUVEC proliferation in a dose-dependent manner (IC50 approximately = 7.4 microg/mL) but had no effect on the growth of HT1080 human fibrosarcoma cells. This suggests that sanguiin H-6 might be a potential anti-angiogenic agent.

Ganoderma lucidum polysaccharides peptide inhibits the growth of vascular endothelial cell and the induction of VEGF in human lung cancer cell

Ganoderma lucidum Polysaccharide Peptide (Gl-PP) has shown some effects as anti-tumors in mice and potential anti-angiogenesis. In this study, we elucidated the possible mechanism of Gl-PP action on anti-angiogenesis of tumor. Our research indicated that the proliferation of HUVECs was inhibited by Gl-PP in a dose-dependent fashion, but not because of cytotoxicity. Flow cytometric studies revealed that Gl-PP treatment of HUVECs could induce cell apoptosis directly. Moreover, addition of Gl-PP also led to a reduction of Bcl-2 anti-apoptotic protein expression and an increase of Bax pro-apoptotic protein expression of HUVECs. Therefore, inducing cell apoptosis by Gl-PP might be the mechanism of inhibiting HUVEC proliferation. Human lung carcinoma cells PG when exposed to high dose of Gl-PP in hypoxia for 18 h resulted in a decrease in the secreted VEGF. Taken together, these findings support the hypothesis that the key attribute of the anti-angiogenic potential of Gl-PP is that it may directly inhibit vascular endothelial cell proliferation or indirectly decrease growth factor expression of tumor cells.

Angiogenesis in non-small cell lung cancer: The prognostic impact of neoangiogenesis and the cytokines VEGF and bFGF in tumours and blood

BACKGROUND

Due to a dismal prognosis of advanced lung cancer, novel screening tools and more effective treatments are clearly needed. Lately, an increasing number of tumour-released angiogenic cytokines which affect vessel formation, tumour growth, invasion, and metastasis have been identified. Vascular endothelial growth factors (VEGFs) and basic fibroblast growth factor (bFGF) are among the most important angiogenic factors. Based on available literature, we have explored the mechanisms of angiogenesis and its prognostic significance in non-small cell lung cancer, estimated by microvessel density (MVD) and the presence of VEGF and bFGF in the tumour and blood from NSCLC patients.

METHODS

Several comprehensive Pubmed searches for the period January 1993 to May 2005 were performed using strategic combinations of the terms non-small cell lung cancer, angiogenesis, vascular endothelial growth factor, basic fibroblast growth factor, tumour expression, microvessel density, circulating, and serum.

RESULTS

NSCLC neoangiogenesis, as measured by MVD, and tumour expression of VEGF are poor prognostic factors for survival (MVD, HR 1.8-2.0; VEGF, HR 1.5). bFGF tumour expression is also associated with poor survival and more aggressive disease. When evaluating the prognostic impact of elevated VEGF levels in blood, 10 of 16 studies (63%) indicated a negative prognostic impact. Of five studies on the prognostic value of circulating bFGF, three studies reported a negative prognostic impact, while one indicated bFGF as a good prognostic factor and one was inconclusive.

CONCLUSION

Angiogenic factors are poor prognostic indicators for tumour aggressiveness and survival in NSCLC. Assessments of circulating levels of VEGF and possibly bFGF may be valuable future tools for treatment planning and monitoring of treatment effect and relapse. First, however, these blood tests need to be standardised and validated in large-scale prospective clinical trials.

Glycine as a therapeutic immuno-nutrient for alcoholic liver disease

Activation of Kupffer cells by gut-derived endotoxin is an important factor in ethanol hepatotoxicity. Further, it was shown that ethanol modulates both the expression and activity of several intracellular signaling molecules and transcription factors in Kupffer cells and chronic ethanol treatment enhances Kupffer cell sensitivity to endotoxin. These findings suggest that inhibition of Kupffer cell activation is effective for clinical application in alcoholic hepatitis. Recently, accumulating lines of evidence suggest a possibility that glycine is useful as an immuno-modulating amino acid. It has been shown that a diet containing glycine improved survival in endotoxin shock by preventing Kupffer cell activation. Glycine most likely prevents the LPS-induced elevation of intracellular Ca concentration in Kupffer cells, thereby minimizing LPS receptor signaling and cytokine production. Indeed, glycine prevents alcohol-induced liver injury in a long-term enteral ethanol feeding rats (Tsukamoto-French) by decreasing production of TNF-alpha in the liver. Moreover, glycine is protective against apoptosis of sinusoidal endothelial cells (SECs) that is one of the initial events in the development of liver injury. On the other hand, epidemiologic data have identified chronic alcohol consumption as a significant risk factor for carcinogenesis. Interestingly, glycine inhibits growth of tumor in vivo most likely because of the inhibition of angiogenesis. It was shown that the inhibitory effect of glycine on growth and migration of endothelial cells is due to activation of a glycine-gated Cl channel. It is hypothesized that the opening of this anion channel hyperpolarizes the cell membrane, blocks influx of Ca through voltage-dependent Ca channel, thereby blunting growth factor-mediated signaling. Therefore, glycine can be used not only for treatment of alcoholic hepatitis, but also for chemoprevention and treatment of hepatocellular carcinoma in alcoholic cirrhosis. Taken together, it is concluded that glycine is a potent therapeutic immuno-nutrient for various kinds of chronic liver diseases including alcoholic liver disease (ALD).

Expression of vascular endothelial growth factor (VEGF)-C and VEGF-D in early gastric carcinoma: correlation with clinicopathological parameters

In this study, we investigated whether expression of vascular endothelial growth factor (VEGF)-C and/or VEGF-D correlates with clinicopathological features of human gastric carcinoma. We immunohistochemically examined the expression of VEGF-C and VEGF-D in 140 archival surgical specimens of submucosally invasive gastric carcinoma. Of these specimens, 32 (22.9%) and 12 (8.6%) showed intense VEGF-C and VEGF-D immunoreactivity in cancer cells, respectively. VEGF-C immunoreactivity was associated with histological type, lymphatic invasion, lymph node metastasis, and microvessel density. No association was identified between VEGF-D immunoreactivity and clinicopathological variables. These results suggest that VEGF-C is a dominant regulator of lymphangiogenesis in early-stage human gastric carcinoma.

Vascular endothelial growth factors and receptors in colorectal cancer: Implications for anti-angiogenic therapy

There are conflicting associations between growth factor expression and clinicopathological variables in colorectal cancer. This study aimed to define the expression of members of the VEGF family and the receptor, VEGFR2, in primary and metastatic sites of colorectal cancer and their relationship to metastatic potential. Thirty colorectal cancers, 12 lymph node metastases and 9 liver metastases were immunostained for VEGF-A, VEGF-C, VEGF-D and VEGFR2. VEGFR2 was expressed by endothelial cells and by the malignant epithelium. VEGF-C and VEGFR2 were co-expressed in the same territory and correlated throughout the primary tumour and in metastatic lymph nodes, but not in liver metastases. Their expression at the invasive tumour edge correlated with expression in metastatic nodes. The benefit of anti-VEGF antibodies might be increased by directing additional therapies against VEGF-C or against the kinase receptors to target redundancy in the system. A component of the therapeutic benefit might be due to a direct anti-tumour effect as well as an anti-angiogenic effect.

Angiogenesis in the human heart: gene and cell therapy

The concept of therapeutic angiogenesis -- stimulation of new vessels growth to restore blood supply to ischemic tissue has been studied in a number of clinical trials in patients with advanced coronary and peripheral arterial disease. This review discusses the main biological processes underlying new vessel growth and addresses applications of growth factor and cell therapy based on the stimulation of angiogenesis. While still very young and controversial, cell therapy has an enormous potential that is yet to be explored. Multiple questions remain unanswered including the choice of the best cell type, patient selection and the mechanism of action. Nevertheless, much should be expected in this area in the next decade with the likely emergence of new therapies for treatment of ischemic diseases.

Evodiamine inhibits in vitro angiogenesis: Implication for antitumorgenicity

Evodiamine, the major bioactive compound isolated from Chinese herbal drug named Wu-Chu-Yu, has been reported to exhibit anti-tumor growth and metastasis. However, the effect of evodiamine on angiogenesis remains to be investigated. We used the fresh medium containing evodiamine or human lung adenocarcinoma cell (CL1 cells) derived conditioned media free of evodiamine to test their capability to induce in vitro angiogenesis, i.e., human umbilical vein endothelial cells (HUVECs) tube formation and invasion. We demonstrated that evodiamine could directly inhibit in vitro HUVECs tube formation and invasion. Locally administered evodiamine also inhibited the in vivo angiogenesis in the chick embryo chorioallantoic membrane (CAM) assay. The gene expression of vascular endothelial growth factor (VEGF) and the p44/p42 mitogen-activated protein kinase (MAPK, ERK) that correlated with endothelial cells angiogenesis were inhibited by evodiamine. We found that the evodiamine-treated CL1 cells derived conditioned medium showed decreased VEGF release and reduced ability of inducing in vitro tube formation. After the collection of conditioned media, the VEGF expression of remaining CL1 cells were determined by Western analyses and revealed that evodiamine decreased VEGF expression. Moreover, administration of recombinant human VEGF(165) (rhVEGF(165)) induced tube formation and ERK phosphorylation by HUVECs, and partially attenuated inhibitory effect of evodiamine. From these results, we suggested that evodiamine is a potent inhibitor of angiogenesis. The mechanism might involve at least the inhibition of VEGF expression, probably through repression of ERK phosphorylation.

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.

A reassessment of vascular endothelial growth factor in central nervous system pathology

✓ Overexpression of vascular endothelial growth factor (VEGF) is associated with several central nervous system (CNS) diseases and abnormalities, and is often postulated as a causative factor and promising therapeutic target in these settings. The authors' goal was to reassess the contribution of VEGF to the biology and pathology of the CNS.

The authors review the literature relating to the following aspects of VEGF: 1) the biology of VEGF in normal brain; 2) the involvement of VEGF in CNS disorders other than tumors (traumatic and ischemic injuries, arteriovenous malformations, inflammation); and 3) the role of VEGF in brain tumor biology (gliomas and the associated vasogenic edema, and hemangioblastomas).

The authors conclude the following: first, that VEGF overexpression contributes to the phenotype associated with many CNS disorders, but VEGF is a reactive rather than a causative factor in many cases; and second, that use of VEGF as a therapeutic agent or target is complicated by the effects of VEGF not only on the cerebral vasculature, but also on astrocytes, neurons, and inflammatory cells. In many cases, therapeutic interventions targeting the VEGF/VEGF receptor axis are likely to be ineffective or even detrimental. Clinical manipulation of VEGF levels in the CNS must be approached with caution.

RSV causes HIF-1alpha stabilization via NO release in primary bronchial epithelial cells

RSV infection is characterized by airway edema. Stabilization of hypoxia inducible factor-1alpha (HIF-1alpha) is important in both inflammation and edema formation. In this study we evaluated whether RSV induced release of nitric oxide (NO) by bronchial airway epithelial cells leading to the stabilization of HIF-1alpha and subsequent transcription of VEGF(165). Primary human bronchial epithelial cells (HBEpC) were used; cell supernatants were analyzed. Western blot analysis was used for the detection of HIF-1alpha. Bronchial airway epithelial monolayer permeability was assessed using electric cell-substrate impedance sensing (ECIS) in real time. There was increased stabilization of HIF-1alpha in RSV infected cells. Addition of an NO inhibitor blocked RSV mediated HIF-1alpha expression. Antagonism of NO also inhibited VEGF production and HBEpC monolayer permeability. Our results demonstrate that in HBEpC, RSV induced NO causes stabilization of HIF-1alpha in vitro.

Minimal contribution of marrow-derived endothelial precursors to tumor vasculature

During embryogenesis, vascular and hemopoietic cells originate from a common precursor, the hemangioblast. Recent evidence suggests the existence of endothelial precursors in adult bone marrow cells, but it is unclear whether those precursors have a role in tumor neovascularization. In this report, we demonstrate that murine bone marrow contains endothelial progenitors, which arise from a cell with self-renewing capacity, and can integrate into tumor microvasculature, albeit at a very low frequency. A transgenic double-reporter strategy allowed us to demonstrate definitively that tumor bone marrow-derived endothelial cells arise by transdifferentiation of marrow progenitors rather than by cell fusion. Single cell transplants showed that a common precursor contributes to both the hemopoietic and endothelial lineages, thus demonstrating the presence of an adult hemangioblast. Furthermore, we demonstrate that increased vascular endothelial growth factor (VEGF)-A secretion by tumor cells, as well as activation of VEGF receptor-2 in bone marrow cells does not alter the mobilization and incorporation of marrow-derived endothelial progenitors into tumor vasculature. Finally, in human umbilical cord blood cells, we show that endothelial precursors make up only approximately 1 in 10(7) mononuclear cells but are highly enriched in the CD133+ cell population. By ruling out cell fusion, we clearly demonstrate the existence of an adult hemangioblast, but the differentiation of marrow stem cells toward the endothelial lineage is an extremely rare event. Furthermore, we show that VEGF-A stimulation of hemopoietic cells does not significantly alter this process.

Multifaceted role of Rho proteins in angiogenesis

The Rho family of GTPases is part of the Ras superfamily. The Rho, Rac, and Cdc42 members of the family are present in mammalian cells and have been the subject of attention of researchers due to their vast spectrum of functions. Rac 1, Cdc42, and RhoA are well-known for their role in the regulation of the actin cytoskeleton in promoting the formation of lamellipodia, filopodia, and stress fibers, respectively. The Rho proteins also participate in the control of cell growth, motility, cell-cell adhesions, morphogenesis, cytoskeletal dynamics, and cellular trafficking. The mechanisms for eliciting these functions have become clearer during the last decade. Concordant with their roles in multiple processes of cellular control, the Rho proteins have been shown to be involved in tumor growth, progression, metastasis, and now angiogenesis.

[6]-Gingerol, a pungent ingredient of ginger, inhibits angiogenesis in vitro and in vivo

[6]-Gingerol, a pungent ingredient of ginger (Zingiber officinale Roscoe, Zingiberaceae), has anti-bacterial, anti-inflammatory, and anti-tumor-promoting activities. Here, we describe its novel anti-angiogenic activity in vitro and in vivo. In vitro, [6]-gingerol inhibited both the VEGF- and bFGF-induced proliferation of human endothelial cells and caused cell cycle arrest in the G1 phase. It also blocked capillary-like tube formation by endothelial cells in response to VEGF, and strongly inhibited sprouting of endothelial cells in the rat aorta and formation of new blood vessel in the mouse cornea in response to VEGF. Moreover, i.p. administration, without reaching tumor cytotoxic blood levels, to mice receiving i.v. injection of B16F10 melanoma cells, reduced the number of lung metastasis, with preservation of apparently healthy behavior. Taken together, these results demonstrate that [6]-gingerol inhibits angiogenesis and may be useful in the treatment of tumors and other angiogenesis-dependent diseases.

Angiogenesis: update 2005

Angiogenesis has critical roles in normal vascular development and in important pathologies including cancer, wound healing and inflammation. This brief article will review the angiogenic response induced by the vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) family of proteins and particularly VEGF-A, thought to be the single most important angiogenic factor. It will also review the steps and mechanisms by which VEGF-A induces the formation of new blood vessels and will provide an initial classification of the abnormal blood vessels that form in pathological angiogenesis. Finally, it will touch on the exciting relationships that are emerging between angiogenesis and the hemostatic and nervous systems.

Gene expression analysis of Tek/Tie2 signaling

The elaboration of the vasculature during embryonic development involves restructuring of the early vessels into a more complex vascular network. Of particular importance to this vascular remodeling process is the requirement of the Tek/Tie2 receptor tyrosine kinase. Mouse gene-targeting studies have shown that the Tie2-deficient embryos succumb to embryonic death at midgestation due to insufficient sprouting and remodeling of the primary capillary plexus. To identify the underlying genetic mechanisms regulating the process of vascular remodeling, transcriptomes modulated by Tie2 signaling were analyzed utilizing serial analysis of gene expression (SAGE). Two libraries were constructed and sequenced using embryonic day 8.5 yolk sac tissues from Tie2 wild-type and the Tie2-null littermates. After tag extraction, 45,689 and 45,275 SAGE tags were obtained for the Tie2 wild-type and Tie2-null libraries, respectively, yielding a total of 21,376 distinct tags. Close to 62% of the tags were uniquely annotated, whereas 10% of the total tags were unknown. Using semiquantitative PCR, the differential expression of eight genes was confirmed that included Elk3, an important angiogenic switch gene which was upregulated in the absence of Tie2 signaling. The results of this study provide valuable insight into the potential association between Tie2 signaling and other known angiogenic pathways as well as genes that might have novel functions in vascular remodeling.

Drugs targeted against protein kinases

Current treatments for cancer (surgery, radiation and chemotherapy) are successful for early stage localised disease but have severe side effects. New treatments are needed to increase the cure rate and life expectancy of patients. With the discovery of oncogenes, tumour suppressor genes and an understanding of their role in the development of the malignant disease, a new era of therapy has begun. Cancer is a manifestation of deregulated signalling pathways that mediate cell growth and programmed cell death. Protein kinases are essential elements in these signalling pathways. In the US, Novartis launched Gleevec (imantinib, STI-571) in May 2001 as the first anticancer drug whose mechanism of action is kinase inhibition. In Phase I trials, 23/24 patients with chronic myelogenous leukaemia (CML) had complete remissions and the drug is relatively non-toxic. Herceptin (trastuzumab) is a monoclonal antibody (mAb) against a member of the growth factor receptor family (HER-2/neu) that was launched in 1998 by Genentech for the treatment of breast cancer. Trastuzumab has an excellent antitumour profile, particularly when used in combination with doxorubicin and paclitaxol. These drugs are pioneering the treatment of cancer based on the molecular understanding of the disease. Numerous drugs that target growth factor receptors and their signalling pathways are in advanced clinical trials. Herein, antibodies against receptors and small molecule inhibitors of kinases in signalling pathways will be summarised. Inter-disciplinary preclinical studies have identified chemicals that target specific kinases. We believe that clinical studies of these agents will yield new anticancer agents that target specific diseases and that are less toxic than current agents.

Review article: angiogenesis soluble factors as liver disease markers

Angiogenesis is the formation of new blood vessels from pre-existing ones; it has been studied at the molecular level in different pathologies and is currently considered a promising novel therapeutic target in cancer. Recently, the use of angiogenesis soluble factors as markers of tumour growth has been investigated. The knowledge gained has led to test their use as therapeutic agents. Additionally, angiogenesis soluble factors could be used for the follow-up of pathologies that currently require monitoring with invasive techniques, like chronic viral hepatitis or renal and haematological diseases. The different factors have been described in multiple studies. In some cases, such as hepatocellular carcinoma, a potential use as prognostic markers has been suggested.

Only a specific subset of human peripheral-blood monocytes has endothelial-like functional capacity

The monocyte population in blood is considered a possible source of endothelial precursors. Because endothelial-specific receptor tyrosine kinases act as regulators of endothelial cell function, we investigated whether expression of the vascular endothelial growth factor receptor-2 (VEGFR-2) on monocytes is important for their endothelial-like functional capacity. Peripheral-blood monocytes expressing vascular endothelial growth factor receptor-2 (VEGFR-2), or CD14+/VEGFR-2+, were isolated, and their phenotypic, morphologic, and functional capacities were compared with those of monocytes negative for this marker (CD14+/VEGFR-2-). CD14+/VEGFR-2+ cells constituted approximately 2% +/- 0.5% of the total population of monocytes and 0.08% +/- 0.04% of mononuclear cells in blood. CD14+/VEGFR-2+ cells exhibited the potential to differentiate in vitro into cells with endothelial characteristics. The cells were efficiently transduced by a lentiviral vector driving expression of the green fluorescence protein (GFP). Transplantation of GFP-transduced cells into balloon-injured femoral arteries of nude mice significantly contributed to efficient reendothelialization. CD14+/VEGFR-2- did not exhibit any of these characteristics. These data demonstrate that the expression of VEGFR-2 on peripheral blood monocytes is essential for their endothelial-like functional capacity and support the notion of a common precursor for monocytic and endothelial cell lineage. Our results help clarify which subpopulations may restore damaged endothelium and may participate in the maintenance of vascular homeostasis.

Roles of neuropilins in neuronal development, angiogenesis, and cancers

Neuropilin-1 (NRP1) and neuropilin-2 (NRP2) are transmembrane glycoproteins that have been characterized as receptors for both semaphorins for neuronal guidance and vascular endothelial growth factor (VEGF) for angiogenesis. Biologic properties of NRPs have been linked to their unique domain structures. However, molecular interaction among NRPs, VEGF, and VEGF receptors is still not clear. Although several types of cancer cells can express NRPs, the role of NRPs in tumor pathogenesis is largely unknown. Thus, future investigations should include determining the effects and mechanisms of NRPs on proliferation, apoptosis, and migration of neuronal , endothelial, and cancer cells. Study of protein-protein interaction, signal transduction pathways, and NRP-mediated gene expression is particularly important to understand NRPs functions, which may have significant clinical applications in the treatment of neurological disorders, cardiovascular diseases, and certain cancers.

Vascular endothelial growth factor acts as an osteolytic factor in breast cancer metastases to bone

Vascular endothelial growth factor (VEGF) is a proangiogenic cytokine that is expressed highly in many solid tumours often correlating with a poor prognosis. In this study, we investigated the expression of VEGF and its receptors in bone metastases from primary human breast tumours and further characterised its effects on osteoclasts in vitro. Breast cancer metastases to bone were immunohistochemically stained for VEGF, its receptors VEGFR1 and 2 (vascular endothelial growth factor receptor 1 and 2), demonstrating that breast cancer metastases express VEGF strongly and that surrounding osteoclasts express both VEGFR1 and VEGFR2. RAW 264.7 cells (mouse monocyte cell line) and human peripheral blood mononuclear cells (PBMCs) were cultured with VEGF, RANKL and M-CSF. VEGF and RANKL together induced differentiation of multinucleated, tartrate-resistant acid phophatase (TRAP)-positive cells in similar numbers to M-CSF and RANKL. The PBMCs were also able to significantly stimulate resorption of mineralised matrix after treatment with M-CSF with RANKL and VEGF with RANKL. We have shown that VEGF in the presence of RANKL supports PBMC differentiation into osteoclast-like cells, able to resorb substrate. Vascular endothelial growth factor may therefore play a role in physiological bone resorption and in pathological situations. Consequently, VEGF signalling may be a therapeutic target for osteoclast inhibition in conditions such as tumour osteolysis.

Quantitative analysis of lymphangiogenic markers for predicting metastasis of human gastric carcinoma to lymph nodes

The spread of tumor cells to regional lymph nodes is an early event of gastric cancer metastasis. In our study, we assessed the expression of lymphangiogenic factors and lymphatic endothelial markers in gastric carcinoma tissues and compared expression levels with the status of lymph node metastasis. We also examined the correlation between lymphatic vessel density (LVD) in primary tumors and lymph node metastasis. Paired biopsy samples (tumor and corresponding normal mucosa) of gastric tissue were obtained from 39 patients with gastric carcinoma. The expression of VEGF-C, VEGF-D, VEGFR-3 and podoplanin mRNAs was assessed by real-time quantitative PCR. The expression of VEGF-C (but not of VEGF-D) was significantly greater in patients with lymph node metastasis than in those without metastasis. The expression of lymphatic endothelial markers VEGFR-3 and podoplanin was also significantly greater in the node-positive group. LVD, as assessed by immunohistochemistry for podoplanin, was correlated with lymph node metastasis. These results indicate that quantitative analysis of lymphangiogenic markers in gastric biopsy specimens may be useful in predicting metastasis of gastric cancer to regional lymph nodes.

Philinopside A, a novel marine-derived compound possessing dual anti-angiogenic and anti-tumor effects

Philinopside A is a novel sulfated saponin isolated from the sea cucumber, Pentacta quadrangulari. The effects of philinopside A on angiogenesis and tumor growth were assessed in a series of models in vitro and in vivo. Our results demonstrated that philinopside A significantly inhibited the proliferation, migration and tube formation of human microvascular endothelial cells (HMECs) in a dose-dependent manner, with average IC(50) values of 1.4 +/- 0.17, 0.89 +/- 0.23 and 0.98 +/- 0.19 microM, respectively. Rat aortas culture assay provides a close imitation of in vivo angiogenesis process and 2-10 microM philinopside A suppressed the formation of new microvessels in cultured rat aortas. Philinopside A 2-10 nmol/egg obviously inhibited angiogenesis in chick embryo chorioallantoic membrane assay. In addition, philinopside A manifested strong anti-tumor activities both in vitro and in vivo. Through immunofluorescent analysis, we found the compound reduced mouse sarcoma 180 tumor volume by inducing apoptosis of tumor and tumor-associated endothelial cells. An examination of the effects of philinopside A on the angiogenesis-related receptor tyrosine kinases (RTKs) showed that philinopside A broadly inhibited all tested RTKs, including vascular endothelial growth factor (VEGF) receptor, fibroblast growth factor (FGF) receptor-1, platelet-derived growth factor (PDGF) receptor-beta and epithelial growth factor (EGF) receptor, with IC(50) values ranging from 2.6-4.9 microM. These results suggest that philinopside A is a promising anti-cancer agent that possesses dual cytotoxic and anti-angiogenic effects that were at least partly due to its inhibitory effects on RTKs.

New antiangiogenic strategies for the treatment of proliferative synovitis

Angiogenesis inhibition, which has been extensively studied for the treatment of various malignancies, is beginning to emerge as a new potential therapy for proliferative synovitis, particularly rheumatoid arthritis (RA). The rheumatoid pannus, the site of inflammation and joint destruction in the rheumatoid synovium, relies on the development of new vasculature to sustain its growth. A host of mediators have been shown to induce angiogenesis at the site of the inflamed synovium; these include vascular endothelial growth factor, fibroblast growth factor, integrin alpha(V)beta3, angiopoietin, prosta-glandin E1 and prostaglandin E2, and matrix metalloproteinases. In addition, hypoxia at the site of synovial inflammation contributes to angiogenesis stimulation. Several naturally-occurring inhibitors exist, such angiostatin and endostatin. There are a number of drugs undergoing study in the treatment of proliferative synovitis, which capitalise on the correlation between angiogenesis inhibition and the reduction of signs and symptoms of RA. Paclitaxel and an anti-integrin alpha(V)beta3 antibody, LM-609, are currently in clinical trials. Other drugs that may inhibit angiogenesis in RA include TNP-470 (formerly called AGM-1470), PPI-2458, PTK-787, bevacizumab and thalidomide. Many of these drugs have shown promise for the treatment of oncologic disorders, and are now being evaluated for the treatment of proliferative synovitis.

Angiogenesis in mucous retention cyst: a human in vivo-like model of endothelial cell differentiation in mucous substrate

BACKGROUND

Mucous retention cysts contain a mucous pool in the lumina, in which pure angiogenic processes are occasionally observed. By using this unique human material, our aim was to understand the in vivo angiogenic process.

METHODS

Fifteen surgical tissue samples of mucous retention cysts of the lip were examined for expression of vascular endothelial markers and extracellular matrix molecules by immunohistochemistry and in situ hybridization (ISH).

RESULTS

Endothelial cells forming new vascular channels showed immunopositivities for CD31, CD34, vascular endothelial growth factor (VEGF), and von Willebrand factor (vWF). These newly formed capillaries were surrounded by tenascin-positive matrices and further by a dense infiltration of CD68-positive cells with foamy to epitheloid appearances. Some of these cells were simultaneously positive for CD34, VEGF, and one of its receptors, Flk-1, and they showed definite mRNA as well as protein signals for tenascin. In addition, these cells often tended to be aligned, which suggested tubule formation.

CONCLUSION

The results suggest that monocyte/macrophage lineage cells are a major source for endothelial cells at least in mucous retention cysts and that tenascin produced by those cells plays an important role in differentiation of endothelial cells.

Gelatinase-mediated migration and invasion of cancer cells

The matrix metalloproteinases(MMP)-2 and -9, also known as the gelatinases have been long recognized as major contributors to the proteolytic degradation of extracellular matrix during tumor invasion. In the recent years, a plethora of non-matrix proteins have also been identified as gelatinase substrates thus significantly broadening our understanding of these enzymes as proteolytic executors and regulators in various physiological and pathological states including embryonic growth and development, angiogenesis and tumor progression, inflammation, infective diseases, degenerative diseases of the brain and vascular diseases. Although the effect of broad-spectrum inhibitors of MMPs in the treatment of cancer has been disappointing in clinical trials, novel mechanisms of gelatinase inhibition have been now identified. Inhibition of the association of the gelatinases with cell-surface integrins appears to offer highly specific means to target these enzymes without inhibiting their catalytic activity in multiple cell types including endothelial cells, tumor cells and leukocytes. Here, we review the multiple functions of the gelatinases in cancer, and especially their role in the tumor cell migration and invasion.

In vivo antitumor efficacy of STAT3 blockade using a transcription factor decoy approach: implications for cancer therapy

The development of more effective prevention and treatment strategies for solid tumors is limited by an incomplete understanding of the critical growth pathways that are activated in carcinogenesis. Signal transducers and activators of transcription (STAT) proteins have been linked to transformation and tumor progression. Several approaches have been used to block STAT3 in cancer cells resulting in reduced proliferation and apoptosis. We tested the hypothesis that blocking STAT3 activation using a transcription factor decoy approach would decrease tumor growth and STAT3 target gene expression in vivo. In a xenograft model of squamous cell carcinoma of the head and neck (SCCHN), daily administration of the STAT3 decoy (25 microg) resulted in decreased tumor volumes, abrogation of STAT3 activation, and decreased expression of STAT3 target genes (VEGF, Bcl-xL, and cyclin D1) compared to treatment with a mutant control decoy. Blockade of STAT3 with the STAT3 decoy also induced apoptosis and decreased proliferation, an effect that was augmented when the STAT3 decoy was combined with cisplatin, both in vitro and in vivo. These results suggest that a transcription factor decoy approach may be used to target STAT3 in cancers that demonstrate increased STAT3 activation including SCCHN.

Clinical significance of serum levels of vascular endothelial growth factor and its receptor in biliary disease and carcinoma

AIM: To investigate the clinical significance of serum vascular endothelial growth factor (VEGF) and soluble VEGF receptor-1 (VEGFR1/Flt-1) (sVEGFR1) levels in biliary diseases.

METHODS: We analyzed the serum levels of these proteins in patients with acute cholangitis (group 1), biliary malignancies (group 2), and primary biliary cirrhosis or primary sclerosing cholangitis (group 3), and in healthy donors (group 4). The influence of inflammation was also analyzed. Serum VEGF levels were expressed as VEGF per platelet (VEGF/PLT, pg/10⁶) in order to exclude the influence of platelet counts.

RESULTS: sVEGFR1 levels were significantly higher in groups 1 and 2 than in the control group, but did not correlate with inflammatory markers. VEGF/PLT levels were generally higher in patients with active inflammation than in those with carcinoma. C-reactive protein strongly correlated with the levels of serum VEGF independently of platelet and leukocyte counts, even in cancer patients. In cancer patients, VEGF/PLT and sVEGFR1 levels might be indicators for evaluating the effect of medical treatment or the disease progression.

CONCLUSION: Serum VEGF and VEGFR1 might be useful markers for gauging the clinical effect of various treatments on patients.

Inhibitors of angiogenesis and cancer-related receptor tyrosine kinases

Inhibition of tumor angiogenesis is an attractive target in cancer therapy. In this context, receptor tyrosine kinases play a pivotal role. Extensive efforts have been made to identify and develop small-molecule inhibitors of these central signaling proteins. Some of these compounds have already passed or are currently in clinical trials to investigate their applicability as anti-cancer drugs. However, the high expectations that are set in antiangiogenic therapy have not yet been accomplished. But there are also new and exciting opportunities for cancer treatment by combining antiangiogenic molecules with newly emerging therapeutics.

Bone marrow expression of vascular endothelial growth factor in myelofibrosis with myeloid metaplasia

The biologic relevance and prognostic impact of angiogenesis is being increasingly recognized in many solid tumors and hematologic malignancies including myelofibrosis with myeloid metaplasia (MMM). Many cytokines including vascular endothelial growth factor (VEGF) have been implicated for neoangiogenesis in MMM. However, the exact humoral basis remains to be elucidated. We examined the expression of VEGF by immunohistochemistry in a prospective cohort of 66 MMM patients, including six with cellular phase disease, and five normal controls. Contrary to most other hematologic malignancies, the distribution and intensity of staining for VEGF in bone marrow was similar between the MMM patients and controls. Interestingly, all six cellular phase patients displayed significantly increased VEGF expression. Thus, upregulation of angiogenic cytokines other than VEGF such as TGF-beta or loss of activity of an anti-angiogenic cytokine might be the dominant pathway of endothelial activation in MMM. However, VEGF might contribute to the process in the early stages of the disease.

Expression of Vascular Endothelial Growth Factor Receptor-2 or Tie-2 on Peripheral Blood Cells Defines Functionally Competent Cell Populations Capable of Reendothelialization

BACKGROUND

Receptor tyrosine kinases that include vascular endothelial growth factor (VEGFR)-1, VEGFR-2, and Tie-2 regulate cardiovascular development and physiological and pathological angiogenesis. We were interested in the phenotypic and functional characterization of peripheral blood cells expressing these receptors and their therapeutic potential in vascular injury.

METHODS AND RESULTS

VEGFR-1+, VEGFR-2+, and Tie-2+ cells constituted approximately 3.0+/-0.2%, 0.8+/-0.5%, and 2.0+/-0.3%, respectively, of the total population of mononuclear cells in blood. Phenotypic analysis demonstrated that all 3 cell populations mainly expressed markers of monocytic/macrophage lineage. Only VEGFR-2+ and Tie-2+ cells phenotypically, morphologically, and functionally differentiated to endothelial cells after culture, whereas VEGFR-1+ cells did not. None of the cell types proliferated in vitro. Only freshly isolated VEGFR-2+ or Tie-2+ cells but not VEGFR-2- or Tie-2- cell populations significantly contributed to efficient endothelialization of balloon-injured femoral arteries of nude mice. Furthermore, these cells also differentiated into -actin-positive smooth muscle cells. Administration of bromodeoxyuridine to animals transplanted with human endothelial progenitor cells showed that VEGFR-2+ and Tie-2+ cells proliferated in vivo.

CONCLUSIONS

These data demonstrate that expression of VEGFR-2 and/or Tie-2 on peripheral blood cells defines functionally competent cell populations that proliferate in vivo and that contribute to reendothelialization. These findings may have implications for a cell-based approach in vascular diseases.

Enhancement of Ad-p53 Therapy with Docetaxel in Head and Neck Cancer

OBJECTIVE

The objective of this project was to determine the mechanisms in which docetaxel enhances Ad-p53 tumor suppressive effects in head and neck cancer.

BACKGROUND

In advanced head and neck squamous cell carcinoma (HNSCC), the 5-year survival rate is less than 40%. Because patients with advanced HNSCC have a high rate of local-regional failure (40-60%) with existing treatment modalities, aggressive local therapy approaches need to be developed. Previous data show that docetaxel or Ad-p53 alone have significant anti-tumor activity in HNSCC. Before testing whether a combination approach (Ad-p53 and docetaxel) could be developed in clinical trials, preclinical experiments were performed.

METHODS

The p53 gene was overexpressed in 2 head and neck squamous carcinoma (HNSCC) cell lines, HN30 and HN12, and a murine Balb/c mucoepidermoid carcinoma (BMEC) cell line. Docetaxel's enhancement of adenoviral transduction (bGAL expression), coxsakie-adenovirus receptor (CAR) expression, and Ad-p53 induction of apoptosis (Annexin V expression) were measured. The modulation of regulators in the cell cycle, apoptosis and signal transduction pathways were measured using Western blot.

RESULTS

Docetaxel increased adenoviral transduction, which was dependent on the dose of docetaxel and levels of Ad-bGAL. The enhanced viral transduction was due in part to the upregulation of the CAR protein. Pretreatment with docetaxel enhanced Ad-p53-induced apoptosis through increased expression of exogenous p53. Together, the combination of docetaxel and Ad-p53 altered expression of key regulators in the cell cycle, apoptosis and signal transduction pathways with an increase in the expression of p53, bax, cleaved PARP, cleaved caspase-3 and phosphorylation of c-Jun at position at Ser. Cyclin A and B1 expression were down regulated by docetaxel and Ad-p53. When comparing the docetaxel-resistant to sensitive cell lines, the altered expression of p27 and skp1 by docetaxel and Ad-p53 were dissimilar between these cell lines.

CONCLUSIONS

Docetaxel enhanced Ad-p53 transduction and increased expression of exogenous p53 gene transfer, apoptosis, and antitumor mechanisms. These results support a clinical combination of docetaxel with p53 gene therapy in patients with head and neck cancer.

Angiopoietin 1 expression levels in the myocardium direct coronary vessel development

Mutational studies in genetically engineered mice have shown that the angiopoietin/Tie2(Tek) signaling pathway is indispensable for vascular development. To further investigate the role of Angiopoietin 1 in heart development, we developed transgenic mice that express Angiopoietin 1 under control of doxycycline in cardiac myocytes. Ninety percent of all transgenic mice die between embryonic day 12.5 and 15.5. Beginning at embryonic day 12.5, transgenic mice exhibit dilated atria, a significant thinning of the myocardial wall, and eventual outflow tract collapse. In addition, hearts of the most severely affected transgenic embryos have no coronary arteries as a result of the defective development and maintenance of the epicardium. The subsequent lack of blood and nutrient delivery to the developing heart may account for decreases in N-cadherin expression and subsequent loss of cell-cell contact leading to cell death, and ultimately the collapse and hemorrhage of the heart. These results suggest a pivotal role for Angiopoietin 1 in cardiovascular development, specifically the development of the epicardium and coronary vasculature.

Molecular introduction to head and neck cancer (HNSCC) carcinogenesis

Of all human cancers, HNSCC is the most distressing affecting pain, disfigurement, speech and the basic survival functions of breathing and swallowing. Mortality rates have not significantly changed in the last 40 years despite advances in radiotherapy and surgical treatment. Molecular markers are currently being identified that can determine prognosis preoperatively by routine tumour biopsy leading to improved management of HNSCC patients. The approach could help decide which early stage patient should have adjuvant neck dissection and radiotherapy, and whether later stage patients with operable lesions would benefit from resection and reconstructive surgery or adopt a conservative approach to patients with poor prognosis regardless of treatment. In the future, understanding these basic genetic changes in HNSCC would be important for the management of HNSCC.

Functional inhibition of secreted angiopoietin: a novel role for angiopoietin 1 in coronary vessel patterning

The angiopoietins are a family of growth factors critical for development and maintenance of the vasculature. The primary amino acid sequence of the angiopoietins predicts that they are comprised of a coiled-coiled and a fibrinogen-like domain. The coiled-coiled domain mediates ligand multimerization, whereas the fibrinogen domain engages the receptor. This multimerization is required to elicit a ligand-mediated biological effect via activation of their receptor Tie2. In vitro and in vivo knockout studies have suggested that the angiopoietins are chemotactic for endothelial cells. We were interested in ascertaining whether the angiopoietins have this activity within the animal proper. To accomplish this we engineered a dominant-interfering form of angiopoietin (Ang) 1, called Ang1cc. Ang1cc contains the coiled-coiled domain, which can heterodimerize with other angiopoietins produced in the same cell. We show that Ang1cc can inhibit Tie2 activation and can inhibit Ang1 activity in vitro and in vivo.

Angiopoietin-1 causes reversible degradation of the portal microcirculation in mice: implications for treatment of liver disease

In many different liver diseases, such as cirrhosis, degradation of the microcirculation, including obliteration of small portal or hepatic veins contributes to disease-associated portal hypertension. The present study demonstrates the importance of angiogenesis in the establishment of arteriovenous shunts and the accompanying changes to the venous bed. One aspect of angiogenesis involves the branching of new vessels from pre-existing ones, and the molecular mechanisms controlling it are complex and involve a coordinated effort between specific endothelial growth factors and their receptors, including the angiopoietins. We modulated the hepatic vasculature in mice by conditionally expressing angiopoietin-1 in hepatocytes. In mice exposed to angiopoietin-1 during development, arterial sprouting, enlarged arteries, marked loss of portal vein radicles, hepatic vein dilation, and suggestion of arteriovenous shunting were observed. Most importantly, these phenotypic changes were completely reversed within 14 days of turning off transgene expression. Expression of excess angiopoietin-1 beginning in adulthood did not fully recapitulate the phenotype, but did result in enlarged vessels. Our findings suggest that controlling excessive angiogenesis during liver disease may promote the restoration of the portal vein circuit and aid in the resolution of disease-associated portal hypertension.

VEGF-DT385 toxin conjugate inhibits mammary adenocarcinoma development in a transgenic mouse model of spontaneous tumorigenesis

Previous experiments have shown that a vascular endothelial growth factor (VEGF)-DT385 toxin conjugate inhibits endothelial cell proliferation, angiogenesis and solid tumor growth in a xenotransplant model system. Here, we report that VEGF-DT385 toxin conjugate effectively inhibits spontaneous tumorigenesis. The C3(1)/SV40 TAg transgenic mouse model of mammary gland carcinogenesis was used to determine the effectiveness of VEGF-DT385 toxin conjugate in delaying the onset of disease and the development of solid tumors. Animals were treated daily with conjugate for a period of 7 days. Therapy was initiated at week 14 of development before any visible adenocarcinomas were evident. Treatment of mice with VEGF-DT385 toxin conjugate significantly delayed the onset of tumorigenesis and inhibited solid tumor growth by more than 92%. Furthermore, conjugate treated animals showed less than twice the number of tumor nodules when compared to control mice. Finally, this vascular targeting agent significantly increased survival time of animals by 5 weeks. VEGF-DT385 toxin conjugate resulted in temporary weight loss and no long-lasting toxicity was seen. More importantly, using this established tumor model, VEGF-DT385 toxin conjugate appeared to be as effective as a similar treatment schedule with recombinant human endostatin. Our results suggest that VEGF-DT385 toxin conjugate is a potent inhibitor of mammary adenocarcinoma growth and might be useful in breast cancer therapy.

Antisense-mediated VEGF suppression in bladder and breast cancer cells

Angiogenesis plays a key role in tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is one of the major angiogenic factors. In the study we have evaluated the efficiency of antisense oligodeoxynucleotides (AS-ODN) against VEGF selected from computational prediction of VEGF mRNA structure. Twenty-five different AS-ODN in two different tumor cell lines were investigated. Treatment of cell line EJ28 by VEGF723 resulted in a 83.5% suppression of VEGF protein when compared with control-ODN. Three further AS-ODN reduced VEGF protein more than 45% in comparison to control-ODN. This was caused by an antisense-specific downregulation of the VEGF transcript determined by real-time PCR. Furthermore, antisense-mediated inhibition of VEGF was associated by a reduced cell viability. In MCF-7 cells VEGF protein was inhibited more than 45% by two AS-ODN. In conclusion, we found that computational prediction of potential single strand mRNA motifs is a well suitable method to elect effective AS-ODN.

Receptor Imaging in Oncology by Means of Nuclear Medicine: Current Status

To date, our understanding of the role of receptors and their cognate ligands in cancer is being successfully translated into the design and development of an arsenal of new, less toxic, and more specific anticancer drugs. Because most of these novel drugs are cytostatic, objective response as measured by morphologic imaging modalities (eg, computed tomography or magnetic resonance imaging) cannot be used as a surrogate marker for drug development or for clinical decision making. Positron emission tomography (PET) can be used to image and quantify the in vivo distribution of positron-emitting radioisotopes such as oxygen-15, carbon-11, and fluorine-18 that can be substituted or added into biologically relevant and specific receptor radioligands. Similarly, single-photon emission computed tomography (SPECT) can be used to image and quantify the in vivo distribution of receptor targeting compounds labeled with indium-111, technetium-99m, and iodine-123. By virtue of their whole-body imaging capacity and the absence of errors of sampling and tissue manipulation as well as preparation, both techniques have the potential to address locoregional receptor status noninvasively and repetitively. This article reviews available data on the in vivo evaluation of receptor systems by means of PET or SPECT for identifying and monitoring patients with sufficient receptor overexpression for tailored therapeutic interventions, and also for depicting tumor tissue and determining the currently largely unknown heterogeneity in receptor expression among different tumor lesions within and between patients.

Dose-dependent response of FGF-2 for lymphangiogenesis

Spatio-temporal studies on the growth of capillary blood vessels and capillary lymphatic vessels in tissue remodeling have suggested that lymphangiogenesis is angiogenesis-dependent. We revisited this concept by using fibroblast growth factor 2 (FGF-2) (80 ng) to stimulate the growth of both vessel types in the mouse cornea. When we lowered the dose of FGF-2 in the cornea 6.4-fold (12.5 ng), the primary response was lymphangiogenic. Further investigation revealed that vascular endothelial growth factor-C and -D are required for this apparent lymphangiogenic property of FGF-2, and when the small amount of accompanying angiogenesis was completely suppressed, lymphangiogenesis remained unaffected. Our findings demonstrate that there is a dose-dependent response of FGF-2 for lymphangiogenesis, and lymphangiogenesis can occur in the absence of a preexisting or developing vascular bed, i.e., in the absence of angiogenesis, in the mouse cornea.

Immunohistochemical demonstration and semi-quantitation of vascular endothelial growth factor in recurrent versus non-recurrent nasal polyps

OBJECTIVE

The expression of some growth factors in nasal polyps has been examined, although investigations addressing the reason for recurrence in some patients are lacking. Vascular endothelial growth factor (VEGF) is expressed by inflammatory cells, as well as by endothelial and epithelial cells of nasal polyps. To determine whether VEGF may play a role in the recurrence of nasal polyps, we aimed to compare VEGF expression in recurrent versus non-recurrent polyps. In addition, expression in polyps from asthmatic patients was compared with that in polyps from non-asthmatics.

MATERIAL AND METHODS

A total of 30 patients with newly diagnosed nasal polyposis were included. Polypectomy was performed at enrolment in the long-term follow-up study. Fifteen patients had only 1 polypectomy (non-recurrence group; median observation period 81 months) and 15 had a median of 6.4 polypectomies (multiple recurrence group; median observation period 108 months). Five of 10 patients with asthma belonged to the non-recurrence group and 5 to the recurrence group. The polyp obtained at the initial polypectomy was examined for expression of VEGF by immunohistochemistry, using a polyclonal antibody. A blinded semi-quantitation and comparison of the intensity of immunolabelling were performed in recurrent versus non-recurrent polyps, as well as in asthmatics versus non-asthmatics.

RESULTS

VEGF expression was seen as varying staining of the polyp surface and gland epithelium, as well as of the vessel endothelium and some stromal mono- and polymorphonuclear leukocytes. Semi-quantitation of the staining intensity showed no significant differences between recurrent and non-recurrent polyps, or between asthmatics and non-asthmatics.

CONCLUSION

Our findings indicate that the level of immunohistochemical expression of VEGF in recurrent and nonrecurrent nasal polyposis is equivalent. Thus, the level of VEGF expression cannot predict a subsequent recurrence. The expression of VEGF is not upregulated in patients with asthma. Further studies are needed to determine the role of VEGF in nasal polyposis, with special reference to different stages of polyp formation, vascularization and growth.

Angiogenic cytokines in patients with idiopathic interstitial pneumonia

BACKGROUND

Angiogenesis has been implicated in the pathogenesis of idiopathic interstitial pneumonia (IIP). The aim of this study was to examine the relationship between plasma concentrations of the angiogenic cytokines interleukin 8 (IL-8), vascular endothelial growth factor (VEGF), and endothelin-1 (ET-1) and clinical parameters of disease progression over a 6 month period to identify potential aetiological mediators and prognostic markers of disease activity in patients with IIP.

METHODS

Forty nine patients with IIP (40 men) were recruited to the study. Plasma cytokine measurements, pulmonary function tests, and high resolution computed tomography (HRCT) scans were performed on recruitment and after 6 months. Plasma cytokine measurements were also performed in 15 healthy volunteers for control purposes.

RESULTS

Patients with IIP had significantly higher median (IQR) baseline concentrations of IL-8 and ET-1 than controls (155 (77-303) pg/ml v 31 (0-100) pg/ml, p<0.001) and (1.21 (0.91-1.88) pg/ml v 0.84 (0.67-1.13) pg/ml, p<0.01), respectively. Baseline concentrations of IL-8, ET-1, and VEGF were significantly related to the baseline HRCT fibrosis score (r = 0.42, p<0.005; r = 0.39, p<0.01; and r = 0.42, p<0.005, respectively). Patients with IIP who developed progressive disease had significantly higher baseline levels of IL-8 (345 (270-497) pg/ml v 121 (73-266) pg/ml, p = 0.001) and VEGF (1048 (666-2149) pg/ml v 658 (438-837) pg/ml, p = 0.019). Over 6 months the change in VEGF was significantly related to the change in HRCT fibrosis score (r = 0.565, p = 0.035) and negatively related to the change in forced vital capacity (r = -0.353, p = 0.035).

Anti-angiogenic effects of Shiraiachrome A, a compound isolated from a Chinese folk medicine used to treat rheumatoid arthritis

The Chinese folk medicine Shiraia bambusicola has long been utilized in the treatment of rheumatoid arthritis, a disease in which angiogenesis plays an important role. We report here the isolation of the compound Shiraiachrome A from S. bambusicola and the demonstration of its anti-angiogenic properties. We found that Shiraiachrome A significantly inhibited the proliferation, migration, and tube formation of human microvascular endothelial cells (HMEC) in a dose-dependent manner, with average IC(50) values of 2.1+/-0.36, 1.97+/-0.44, and 1.65+/-0.59 microM, respectively. In addition, Shiraiachrome A inhibited the formation of new microvessels in a rat aorta culture model as well as in the chick embryo chorioallantoic membrane (CAM) assay. Investigation of the mechanism of action of Shiraiachrome A demonstrated that this compound suppressed the autophosphorylation of four receptor tyrosine kinases (RTKs), with IC(50) values ranging from 2.2 to 4.3 microM. These results suggest that Shiraiachrome A inhibits angiogenesis by blocking growth factor-stimulated autophosphorylation of RTKs. These findings also indicate that Shiraiachrome A may be a potent therapeutic agent for angiogenesis-related diseases such as cancer, rheumatoid arthritis, and diabetic retinopathy.

Suppression of angiogenesis by the plant alkaloid, sanguinarine

Sanguinarine is a benzophenanthridine alkaloid derived from the root of Sanguinaria canadensis. Its principal pharmacologic use is in dental products where it has antibacterial, antifungal, and anti-inflammatory activities that reduce gingival inflammation and supragingival plaque formation. Angiogenesis is indispensable for inflammation, and most angiogenesis is dependent on vascular endothelial growth factor (VEGF). However, the effect of sanguinarine on angiogenesis is not known. In the present study, we examined the effect of sanguinarine on VEGF-induced angiogenesis in vitro and in vivo. Interestingly, sanguinarine markedly suppressed VEGF-induced endothelial cell migration, sprouting, and survival in vitro in a dose-dependent manner at nanomolar concentrations. Furthermore, sanguinarine potently suppressed blood vessel formation in vivo in mouse Matrigel plugs and the chorioallantoic membrane of chick embryos. Our biochemical assays indicated that sanguinarine strongly suppressed basal and VEGF-induced Akt phosphorylation, while it did not produce any changes in VEGF-induced activation of ERK1/2 and PLCgamma1. Therefore, we conclude that sanguinarine is a potent antiangiogenic natural product, and its mode of action could involve the blocking of VEGF-induced Akt activation. Thus, in addition to antibacterial, antifungal, and anti-inflammatory activities, sanguinarine has a novel antiangiogenic role.