Endo-PDI is required for TNFα-induced angiogenesis.

Protein disulfide isomerase (PDI) and its homologs are oxidoreductases facilitating protein folding in the ER. Endo-PDI (also termed ERp46) is highly expressed in endothelial cells. It belongs to the PDI family but its physiological function is largely unknown. We studied the role of Endo-PDI in endothelial angiogenic responses. Stimulation of human umbilical vein endothelial cells (with TNFα (10ng/ml) increased ERK1/2 phosphorylation. This effect was largely attenuated by Endo-PDI siRNA, whereas JNK and p38 MAP kinase phosphorylation was Endo-PDI independent. Similarly, TNFα-stimulated NF-κB signaling determined by IκBα degradation as well as TNFα-induced ICAM expression was unaffected by Endo-PDI siRNA. The action of Endo-PDI was not mediated by extracellular thiol exchange or cell surface PDI as demonstrated by nonpermeative inhibitors and PDI-neutralizing antibody. Moreover, exogenously added PDI failed to restore ERK1/2 activation after Endo-PDI knockdown. This suggests that Endo-PDI acts intracellularly potentially by maintaining the Ras/Raf/MEK/ERK pathway. Indeed, knockdown of Endo-PDI attenuated Ras activation measured by G-LISA and Raf phosphorylation. ERK activation influences gene expression by the transcriptional factor AP-1, which controls MMP-9 and cathepsin B, two proteases required for angiogenesis. TNFα-stimulated MMP-9 and cathepsin B induction was reduced by silencing of Endo-PDI. Accordingly, inhibition of cathepsin B or Endo-PDI siRNA blocked the TNFα-stimulated angiogenic response in the spheroid outgrowth assays. Moreover ex vivo tube formation and in vivo Matrigel angiogenesis in response to TNFα were attenuated by Endo-PDI siRNA. In conclusion, our study establishes Endo-PDI as a novel, important mediator of AP-1-driven gene expression and endothelial angiogenic function.

Mechanisms for PDGF, a serum cytokine, stimulating loss of corneal keratocyte crystallins.

PURPOSE: As corneal stromal cells (keratocytes) become activated before transition to the fibroblastic repair phenotype in response to injury (in situ) or serum (in culture), the corneal crystallins, transketolase (TKT) and aldehyde dehydrogenase (ALDH1A1), are lost. The authors previously showed that the serum cytokine platelet-derived growth factor-BB (PDGF), but not transforming growth factor beta2 (TGF-beta2), stimulates TKT loss. The goal of this study was to further define the molecular mechanisms for PDGF-stimulated loss of crystallins to elucidate the pathway for keratocyte activation. METHODS: Freshly isolated rabbit corneal keratocytes were plated in serum-free medium with or without PDGF and/or specific inhibitors of the PDGF-relevant signal pathway components, PDGF receptor, PI3K/AKT, or ras-initiated MAPK proteins. Intracellular TKT protein levels were quantified by immunoblotting. Ubiquitinated TKT levels were assessed by immunoprecipitation, and TKT messenger RNA (mRNA) levels were quantified by quantitative reverse transcription-polymerase chain reaction. RESULTS: PDGF treatment at the same time as inhibition of PDGF receptor, Akt, JNK, and ubiquitin-proteasome pathway prevented PDGF-induced TKT protein loss. In contrast, treatment with PDGF did not affect TKT mRNA levels. CONCLUSIONS: The results suggest that PDGF-stimulated TKT loss is mediated through cross talk between PI3K-independent Akt and JNK. This signaling pathway leads to the degradation of existing TKT protein but does not compromise the accumulation of TKT mRNA. Therefore, cells retain the potential to reaccumulate TKT protein that is enabled by PDGF removal. These findings suggest that targeting PDGF signaling could improve repair outcomes after surgical procedures in the cornea.

Aromatic hydrocarbon receptor inhibits lysophosphatidic acid-induced vascular endothelial growth factor-A expression in PC-3 prostate cancer cells.

Lysophosphatidic acid (LPA) is a lipid growth factor with multiple biological functions and has been shown to stimulate cancer cell secretion of vascular endothelial growth factor-A (VEGF-A) and trigger angiogenesis. Hypoxia-inducible factor-1 (HIF-1), a heterodimer consisting of HIF-1α and HIF-1ß (also known as aromatic hydrocarbon receptor nuclear translocator (ARNT)) subunits, is an important regulator of angiogenesis in prostate cancer (PC) through the enhancement of VEGF-A expression. In this study, we first confirmed the ability of LPA to induce VEGF-A expression in PC-3 cells and then validated that LPA-induced VEGF-A expression was regulated by HIF-1α and ARNT through phosphatidylinositol 3-kinase activation. Aromatic hydrocarbon receptor (AHR), a receptor for dioxin-like compounds, functions as a transcription factor through dimerization with ARNT and was found to inhibit prostate carcinogenesis and vanadate-induced VEGF-A production. Since ARNT is a common dimerization partner of AHR and HIF-1α, we hypothesized that AHR might suppress LPA-induced VEGF-A expression in PC-3 cells by competing with HIF-1α for ARNT. Here we demonstrated that overexpression and ligand activation of AHR inhibited HIF-1-mediated VEGF-A induction by LPA treatment of PC-3 cells. In conclusion, our results suggested that AHR activation may inhibit LPA-induced VEGF-A expression in PC-3 cells by attenuating HIF-1α signaling, and subsequently, suppressing angiogenesis and metastasis of PC. These results suggested that AHR presents a potential therapeutic target for the prevention of PC metastasis.

[Synthesis and characterization of protocatechuic acid derivants].

To explore the effects of protocatechuic acid (PCA) and its derivants on angiogenesis of the chick embryo chorioallantoic membrane (CAM) and scavenging DPPH radical in vitro. The protection of benzyl and alkaline hydrolysis of benzyl ester were employed. The structures of PCA-1, PCA-2 and PCA-3, the derivates of PCA, were elucidated by 1H, 13C-NMR and MS data The bioactivity of PCA and its derivants was evaluated on the models of DPPH radical and chick embryo chorioallantoic membrane (CAM), respectively. PCA and PCA-1 showed the best activity of scavenging DPPH radical among all the compounds. In contrast to PCA-2, PCA and PCA-3 displayed inhibition to angiogenesis (P < 0.001). Pyrocatechol hydroxyl is the active site of PCA on scavenging DPPH radical in vitro. PCA with carboxyl and without pyrocatechol hydroxyl seems to show promotion to angiogenesis, but it needs more evidences.

NGF promotes hemodynamic recovery in a rabbit hindlimb ischemic model through trkA- and VEGFR2-dependent pathways.

Nerve growth factor (NGF) has been reported to play an important role in physiological and pathological angiogenesis. Based on these observations, we hypothesized that NGF may induce the formation of functional blood vessels in a hindlimb ischemic rabbit model. Hindlimb ischemia was induced in 34 rabbits bilaterally by endovascular embolization of femoral arteries. On the 7th, 14th, and 20th postembolization days, NGF was injected intramuscularly, in 1 ischemic limb, and vehicle was injected in the contralateral control limb. On the 40th day, newly developed collateral vessels (diameter >500 µm) were quantified by transauricular intraarterial subtraction angiography. Perfusion analysis of an in vivo dynamic computed tomography study was performed to the limbs to investigate the hemodynamic recovery of the distal ischemic tissues. Functional estimation of limb perfusion showed a statistically significant increase of blood flow and blood volume for NGF. However, the increase of the collateral vessels was not detectable angiographically, providing evidence for the existence of a NGF-stimulated capillary angiogenic network but not increase of arteriogenesis. The combination of NGF with either tropomyosin-related kinase type A or vascular endothelial growth factor receptor 2 antagonists abolished the NGF-induced hemodynamic recovery. These findings provide new insights into understanding the involvement of NGF in vascular formation and its applications in therapeutic angiogenesis.

CXC chemokine KC fails to induce neutrophil infiltration and neoangiogenesis in a mouse model of myocardial infarction.

BACKGROUND: Chemokines and neutrophils, known as important players in the inflammatory cascade, also contribute to heart tissue recovery and scar formation after myocardial infarction (MI). The objective of this study was to determine the importance of ELR-containing CXC chemokine KC in neutrophil infiltration and neoangiogenesis, in a mouse model of chronic MI. METHODS AND RESULTS: MI was induced in mice divided in four groups: control (untreated), anti-KC "later" (anti-KC antibody injections started 4 days after MI and then delivered every 72 hours for 3 weeks, to inhibit angiogenesis), anti-KC "earlier" (anti-KC antibody injections 1 day before and 1 day after MI, to block neutrophil infiltration), anti-KC (anti-KC antibody injections 1 day before and 1 day after MI, and then every 72 hours for 3 weeks). The efficiency of the anti-KC treatment was determined by the measurement of KC serum concentration and immunofluorescence staining, in each of the four groups. Surprisingly, we did not find any difference in neutrophil infiltration in the infarcted area between untreated and treated animals. Moreover, the heart function, infarct size, and neoangiogenesis were not different between the four groups. As expected, a comparable anti-CXCR2 treatment of mice before and after MI was able to significantly reduce neutrophil infiltration into the infarcted area and angiogenesis, but also to reduce the infarction size after long or "later" treatment. CONCLUSIONS: The major finding of our study is that KC, a potent neutrophil chemoattractant and an established angiogenic factor, failed to interfere in the post-infarction inflammatory response, in wound healing and scar formation after MI. Therefore, these aspects need to be carefully taken into account when devising therapeutic strategies for myocardial infarction and ischemic cardiomyopathy.

Primary human endothelial cells secrete agents that reduce responsiveness to lysophosphatidic acid (LPA).

The plasma level of LPA (lysophosphatidic acid) (200-600 nM) is well within the range that promotes proliferation and migration of vascular ECs (endothelial cells), yet vessels are quiescent and stable. In this report, we considered one explanation for this paradox: that ECs secrete agents that attenuate responsiveness to LPA. Indeed, we observed that CM (conditioned medium) from confluent, quiescent cultures of primary HUVECs (human umbilical vein ECs) contained an agent that inhibited LPA-mediated signalling events and cellular responses. The putative inhibitor, which we tentatively call ILMR (inhibitor of LPA-mediated responsiveness) seemed to act on cells (instead of at the level of LPA) by suppressing the ability of LPA receptor 1 to signal. The amount and/or activity of ILMR was regulated by growth factors; exposing HUVECs to VEGF-A (vascular endothelial growth factor A), but not bFGF (basic fibroblast growth factor), reduced the amount and/or activity of ILMR in CM. We conclude that in addition to promoting angiogenesis directly, VEGF-A can also act indirectly by modulating the bioactivity of angiomodulators such as LPA.

The elevation in circulating anti-angiogenic factors is independent of markers of neutrophil activation in preeclampsia.

BACKGROUND: Severe preeclampsia is associated with increased neutrophil activation and elevated serum soluble endoglin (sEng) and soluble Flt-1 (sFlt-1) in the maternal circulation. To dissect the contribution of systemic inflammation and anti-angiogenic factors in preeclampsia, we investigated the relationships between the circulating markers of neutrophil activation and anti-angiogenic factors in severe preeclampsia or systemic inflammatory state during pregnancy. METHODS AND RESULTS: Serum sEng, sFlt-1, placenta growth factor, interleukin-6 (IL-6), calprotectin, and plasma α-defensins concentrations were measured by ELISA in 88 women of similar gestational age stratified as: severe preeclampsia (sPE, n = 45), maternal systemic inflammatory response (SIR, n = 16) secondary to chorioamnionitis, pyelonephritis or appendicitis; and normotensive controls (CRL, n = 27). Neutrophil activation occurred in sPE and SIR, as α-defensins and calprotectin concentrations were two-fold higher in both groups compared to CRL (P < 0.05 for each). IL-6 concentrations were highest in SIR (P < 0.001), but were higher in sPE than in CRL (P < 0.01). sFlt-1 (P < 0.001) and sEng (P < 0.001) were ≈20-fold higher in sPE compared to CRL, but were not elevated in SIR. In women with sPE, anti-angiogenic factors were not correlated with markers of neutrophil activation (α-defensins, calprotectin) or inflammation (IL-6). CONCLUSIONS: Increased systemic inflammation in sPE and SIR does not correlate with increased anti-angiogenic factors, which were specifically elevated in sPE indicating that excessive systemic inflammation is unlikely to be the main contributor to severe preeclampsia.

Glyceollins inhibit platelet-derived growth factor-mediated human arterial smooth muscle cell proliferation and migration.

Platelet-derived growth factor (PDGF)-BB can induce abnormal proliferation and migration of vascular smooth muscle cells (VSMC) that are involved in the development of CVD. In our preliminary study, phytoalexin glyceollins (glyceollins I, II and III) isolated from soyabean seeds cultured with Aspergillus sojae showed strong antioxidant and anti-inflammatory activity. Since antioxidants showed beneficial effects on chronic inflammatory diseases, the purpose of the present study was to examine the effects of glyceollins on PDGF-induced proliferation and migration in human aortic smooth muscle cells (HASMC). Incubation of resting HASMC with glyceollins for 24 h significantly diminished PDGF-increased cell number and DNA synthesis in a dose-dependent manner without any cytotoxicity. In addition to blocking of the PDGF-inducible progression through the G0/G1 to the S phase of the cell cycle, glyceollins down-regulated the expression of cyclin-dependent kinase (CDK)2 and cyclin D1, and up-regulated the expression of CDK inhibitors such as p27kip1 and p53.Glyceollins also effectively inhibited reactive oxygen species generation and phosphorylation of PDGF receptor-ß, phospholipase Cγ1, Akt and extracellular signal-regulated kinase 1/2 by PDGF stimulation. Furthermore, glyceollins were found to inhibit PDGF-induced dissociation of actin filaments and cell migration. Thus, the results suggest that glyceollins could become a potent therapeutic agent for regulating VSMC-associated vascular disease such as atherosclerosis and restenosis after angioplasty.

[New insights into the pathogenesis of pre-eclampsia: the role of angiogenesis-inhibiting factors]. / Nieuwe inzichten in pathogenese van pre-eclampsie. De rol van angiogeneseremmende factoren.

The pathogenesis of pre-eclampsia is biphasic. The first phase is characterised by insufficient placentation and the second phase by an increased placental release of 2 anti-angiogenic factors, namely, soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng). Within maternal circulation, sFlt-1 and sEng inhibit the effects of vascular endothelial growth factor (VEGF) and transforming growth factor ß (TGFß). This results in endothelial cell activation and inflammation, and eventually leads to the clinical syndrome of pre-eclampsia. The rise in plasma concentrations of sFlt-1 and sEng precedes the development of pre-eclampsia with 6-8 weeks. Whether elevations in the plasma concentrations of sFlt and sEng, combined with a decrease in placental growth factor concentrations, can be utilised as a predictor for pre-eclampsia is currently under investigation.

Role of angiogenic factors in acute experimental Strongyloides venezuelensis infection.

This study aims to investigate the role of angiogenic factors in the pathogenesis of experimental strongyloidiasis. Two complementary approaches were used: Firstly, CD1 mice were treated with endostatin, an angiogenesis inhibitor, and infected with Strongyloides venezuelensis. Also, the mechanisms involved in this process were studied. Parasitological examination revealed a significant decrease in egg per gram of faeces, number of collected larvae from lung tissue and number of collected adult females in mice treated with endostatin. Direct mechanisms with diminution of angiogenesis factors and an indirect mechanism with increase of eosinophil perhaps produced their effect. Secondly, the effect of the antigens responsible for stimulation of angiogenic factors [vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2)] from alveolar macrophages and the mechanisms involved in their production were investigated. Alveolar macrophage cells obtained by bronchoalveolar lavage were incubated at different concentrations of somatic and excretory/secretory antigens of S. venezuelensis. Also, mRNA levels of VEGF and FGF2 in macrophage cells were detected by RT-PCR. L3-PBS larvae antigens induced angiogenic factors. The relationship between angiogenesis factors and nitric oxide has been observed using nitric oxide synthase inhibitors.

Angiogenin is involved in lung adenocarcinoma cell proliferation and angiogenesis.

Angiogenin, a basic heparin-binding protein, has been shown to play a key role in tumor growth and angiogenesis. It was found in the present study that 67 out of 100 lung adenocarcinomas exhibited angiogenin nuclear expression, and this nuclear expression correlated with vascular and pleural invasion as well as positive lymph node metastasis. To down-regulate angiogenin expression, we constructed an adenoviral-vector based short hairpin RNA system. ELISA, real-time qPCR and immunocytochemical staining demonstrated that adenoviral-vector based siRNA decreased angiogenin mRNA level and protein secretion, and inhibited angiogenin nuclear expression in A549 cells, resulting in marked inhibition on ribosomal RNA transcription, in vitro cell proliferation, soft agar colony formation, and xenograft tumor proliferation and angiogenesis. Experiments with neomycin further confirmed that angiogenin nuclear expression played an important role in tumor growth. Based on these data, we concluded that angiogenin nuclear expression played a dual role in the growth of lung adenocarcinoma with respect to cancer cell proliferation and angiogenesis.

Nicotine: a pro-angiogenic factor.

Angiogenesis, the formation of new blood vessels from pre-existing ones, is regulated by the balance between angiogenic activating and inhibiting factors. Recent evidence indicates that nicotine, an alkaloid compound, presents pro-angiogenic effects in certain concentrations. Nicotine-induced angiogenesis results from the stimulation of non-neuronal nicotinic acetylcholinergic receptors (particularly alpha 7-NAChR subtype) and involves growth factor secretion and activation of intracellular signalling pathways. Although nicotine is a constituent of tobacco smoke, its contribution towards pathophysiology of several tobacco-associated pathologies is controversial. Nowadays, nicotine is used in tobacco smoke cessation programs, but, again, its use is still a matter of discordance regarding cardiovascular morbidity. Nevertheless, given the established effects of nicotine-induced angiogenesis, this alkaloid might be of therapeutic value in situations of inefficient angiogenesis, such as peripheral vascular impairment and tissue ischemia. Conversely, blockade of nicotine pathway can be helpful in complications exhibiting excessive angiogenesis, namely in diabetic retinopathy and nephropathy or neoplasia. Knowing that nicotine is involved in many angiogenic-associated disorders with a high prevalence in the western world, and that this alkaloid widely used in smoke cessation programs, elucidation of the action of nicotine on the vascularization process is of utmost importance. The current paper provides an overview of the effects of nicotine in angiogenesis.

Grape seed proanthocyanidins inhibit the growth of human non-small cell lung cancer xenografts by targeting insulin-like growth factor binding protein-3, tumor cell proliferation, and angiogenic factors.

PURPOSE: Lung cancer is a leading cause of cancer-related deaths worldwide. Here, we assessed the chemotherapeutic effect of grape seed proanthocyanidins (GSPs) on human non-small cell lung cancer (NSCLC) cells in vitro and in vivo using a tumor xenograft model. EXPERIMENTAL DESIGN: The effects of GSPs on human NSCLC cell lines in terms of cellular proliferation were determined. The chemotherapeutic effects of a GSP- supplemented AIN76A control diet fed to nude mice bearing tumor xenografts (A549 and H1299) were evaluated in terms of biomarkers of cell proliferation and angiogenesis and on insulin-like growth factor binding protein-3 using immunohistochemical detection, ELISA, and Western blotting. RESULTS: In vitro treatment of NSCLC cells with GSPs resulted in inhibition of cellular proliferation. Administration of GSPs (0.1%, 0.2%, and 0.5%, w/w) as a supplement of an AIN76A control diet resulted in a dose-dependent inhibition of the growth of NSCLC (A549 and H1299) tumor xenografts in athymic nude mice (25-76%; P < 0.05-0.001). The growth-inhibitory effect of GSPs on the NSCLC xenograft tumors was associated with the enhancement of the levels of insulin-like growth factor binding protein-3 in the tumor microenvironment and plasma and antiproliferative, antiangiogenic, and proapoptotic effects. CONCLUSIONS: This preclinical study reveals for the first time that dietary GSPs have the ability to inhibit the growth of human NSCLC tumor xenografts grown in vivo in athymic nude mice. More studies are needed to develop GSPs as a pharmacologically safe agent for the prevention of lung cancer in humans.

Use of the tyrosine kinase inhibitor sunitinib in a patient with von Hippel-Lindau disease: targeting angiogenic factors in pheochromocytoma and other von Hippel-Lindau disease-related tumors.

CONTEXT: von Hippel-Lindau disease is characterized by highly vascularized tumors of multiple organs. EVIDENCE ACQUISITION: We present a patient with von Hippel-Lindau disease with multiple renal and pancreatic tumors and a malignant pheochromocytoma infiltrative of the sacrum and associated with lymph nodule metastases. The pheochromocytoma expressed high protein level of vascular endothelial growth factor and platelet-derived growth factor-beta receptor. The patient presented with a poor performance status, severe pelvic pain, weight loss, and manifestations of catecholamine excess. EVIDENCE SYNTHESIS: Treatment against malignant pheochromocytoma with surgery, chemotherapy, or participation in clinical trials was not feasible because of the patient's poor performance status, the presence of multiple tumors, and the extension of the pheochromocytoma into the bones. Patient was treated with sunitinib, a potent tyrosine kinase inhibitor of vascular endothelial growth factor, platelet-derived growth factor, RET, c-KIT, and FLT-3 receptors. Six months of treatment with sunitinib was associated with normalization of the patient's performance status and blood pressure, absence of symptoms of catecholamine excess, weight gain, disappearance of pain, shrinkage of each of the tumors (50% in the largest renal tumor, 38% in the largest islet cell tumor, 21% in the pelvic malignant pheochromocytoma), and reduction of plasma normetanephrines and chromogranin A. CONCLUSION: This study provides evidence that targeting tyrosine kinase receptors such as the vascular endothelial growth factor pathway and the platelet-derived growth factor-beta receptor may have value in the treatment of VHL-related tumors including pheochromocytoma.

Preparation of sodium deoxycholate (DOC) conjugated heparin derivatives for inhibition of angiogenesis and cancer cell growth.

We describe new DOC (sodium deoxycholate)-heparin nanoparticles for in vivo tumor targeting and inhibition of angiogenesis based on chemical conjugation and the enhanced permeability and retention (EPR) effect. Heparin has been used as a potent anticoagulant agent for 70 years, and has recently been found to inhibit the activity of growth factors which stimulate the smooth muscle cells around tumor. From the results, DOC and heparin were conjugated by bonding carboxyl groups of heparin with amine groups of aminated sodium deoxycholate. Larger antitumor effects of the DOC-heparin VI (8.5 mol of DOC coupled with 1.0 mol heparin) were achieved in animal studies, compared to heparin alone. We confirmed that the conjugated heparin retained its ability to inhibit binding with angiogenic factor, showing a significant decrease in endothelial tubular formation. These results provide new insights into the nontoxic anticancer drug carrier as well as the design of multifunctional bioconjugates for targeted drug delivery.

Targeting vasculature in urologic tumors: mechanistic and therapeutic significance.

Recent advances toward understanding the molecular mechanisms regulating cancer initiation and progression provide new insights into the therapeutic value of targeting tumor vascularity by interfering with angiogenic signaling pathways. The functional contribution of key angiogenic factors toward increased vascularity characterizing metastatic tumors and their therapeutic exploitation is considered in three major urologic malignancies, renal, bladder, and prostate cancer. With the realization that the success of the therapeutic efficacy of the various anti-angiogenic approaches for the treatment of urologic tumors has yet to be proven clinically, the challenge remains to select critical angiogenesis pathways that can be targeted for an individual tumor. Here we discuss the major mechanisms that support formation of vasculature in renal, bladder, and prostate tumors and the current results of targeting of specific molecules/regulators for therapeutic intervention against metastastic disease.

Connecting a tumor to the environment.

Tumor cells are not only susceptible to signals from the environment, but they likewise release signal substances. It is well known that tumor cells secrete angiogenic factors--most prominently the vascular endothelial growth factor--which initiate the vascularization of the tumor for its nourishment. This process has been termed neoangiogenesis. Besides this, two further processes have recently been discovered that facilitate the interaction of the tumor with the lymphatic system and the nervous system, named lymphangiogenesis and neoneurogenesis. These three "geneses" have a cognate, in part common regulation and conjointly promote metastasis development. Neoangiogenesis and lymphangiogenesis provide the structures for the two routes of tumor cell dissemination, i.e. either hematogenous or lymphatic. Neoneurogenesis accomplishes the innervation of the tumor by the ingrowth of nerve endings into the tumor and alternatively or additionally by the protection of existing nerve cells from destruction. These tumor-innervating nerve cells may release neurotransmitters which are proliferative or promigratory signals for the tumor cells. Furthermore, nerve fibers are used as routes for tumor cell dissemination, too, which is known as perineural invasion.

Stimulation of angiostatic platelet factor-4 variant (CXCL4L1/PF-4var) versus inhibition of angiogenic granulocyte chemotactic protein-2 (CXCL6/GCP-2) in normal and tumoral mesenchymal cells.

Chemokines affect inflammation and cancer through leukocyte attraction and angiogenesis. Here, we demonstrate that CXCL4L1/platelet factor-4 variant (PF-4var), a highly angiostatic chemokine, is poorly chemotactic for phagocytes and is inducible in monocytes by inflammatory mediators but remained undetectable in macrophages and neutrophils. In addition, CXCL4L1/PF-4var production by mesenchymal tumor cells was evidenced in vitro and in vivo by specific ELISA and immunohistochemistry. CXCL4L1/PF-4var, but not CXCL4/PF-4, was coinduced with the angiogenic chemokine CXCL6/granulocyte chemotactic protein-2 (GCP-2) by cytokines, e.g., IL-1beta and IL-17, in sarcoma cells, but not in diploid fibroblasts. Furthermore, the induction of CXCL6/GCP-2 in endothelial cells by IL-1beta was enhanced synergistically by TNF-alpha but inhibited by IFN-gamma, which synergized with IL-1beta to produce the angiostatic CXCL10/IFN-gamma-induced protein-10. These findings indicate that the equilibrium between angiostatic and angiogenic factors during inflammation and tumor progression is rather complex and differs depending on the chemokine, cell type, and stimulus. Selective intervention in the chemokine network may drastically disturb this delicate balance of angiogenesis and tissue repair. Application of angiostatic CXCL4L1/PF-4var without attraction of protumoral phagocytes may be beneficial in cancer therapy.

[Clinical importance of angiogenesis and angiogenic factors in oncohematology]. / Kliniczne znaczenie angiogenezy i czynników ja modyfikujacych w onkohematologii.

The vascularization is a very important part of a structure of each tissue both normal, including bone marrow stroma, and pathologically changed. Neoplastic tissues secure supplying in necessary substances for growth and expansion through regulated by its own cells neovasculation. Key role in multipotential cell's differentiation to endothelial cells plays regulatory system consisted of vascular-epithelial growth factor's family (VEGF B, C, D), receptors VEGFR-1, -2, -3, and system Tie2/angiopoetins. Stimulation and importance of angiogenesis for expansion of neoplastic diseases is a current problem in oncology. It is pointed to importance of neovascularization in pathogenesis of acute and chronic leukemias, lymphomas and multiple myeloma. The knowledge of the importance ofvascularization of neoplastic tissues is availing in therapy (researching of substances inhibiting angiogenesis--semaxinib, SU6668, ZD 6474, thalidomid, cetuximab, gefitinib, interferon-alpha, irradiation and others), in diagnostics as a monitoring of a success of the therapy, and in prognosis. Inhibitors ofangiogenesis are antineoplastic drugs with relatively lower toxicity, and lower risk of drug-resistance than conventional chemotherapy what has the importance especially during prolong administration, so they can be an alternative way of therapeutic process. During qualification for antiangiogenic therapy it is necessary to have a consciousness of its limited efficiency.