gro-beta, a -C-X-C- chemokine, is an angiogenesis inhibitor that suppresses the growth of Lewis lung carcinoma in mice

Bioinformatic Analysis of the CXCR2 Ligands in Cancer Processes

Human CXCR2 has seven ligands, i.e., CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8/IL-8-chemokines with nearly identical properties. However, no available study has compared the contribution of all CXCR2 ligands to cancer progression. That is why, in this study, we conducted a bioinformatic analysis using the GEPIA, UALCAN, and TIMER2.0 databases to investigate the role of CXCR2 ligands in 31 different types of cancer, including glioblastoma, melanoma, and colon, esophageal, gastric, kidney, liver, lung, ovarian, pancreatic, and prostate cancer. We focused on the differences in the regulation of expression (using the Tfsitescan and miRDB databases) and analyzed mutation types in CXCR2 ligand genes in cancers (using the cBioPortal). The data showed that the effect of CXCR2 ligands on prognosis depends on the type of cancer. CXCR2 ligands were associated with EMT, angiogenesis, recruiting neutrophils to the tumor microenvironment, and the count of M1 macrophages. The regulation of the expression of each CXCR2 ligand was different and, thus, each analyzed chemokine may have a different function in cancer processes. Our findings suggest that each type of cancer has a unique pattern of CXCR2 ligand involvement in cancer progression, with each ligand having a unique regulation of expression.

Modulating Properties of Piroxicam, Meloxicam and Oxicam Analogues against Macrophage-Associated Chemokines in Colorectal Cancer

The mechanisms underlying the antineoplastic effects of oxicams have not been fully elucidated. We aimed to assess the effect of classic and novel oxicams on the expression/secretion of macrophage-associated chemokines (RTqPCR/Luminex xMAP) in colorectal adenocarcinoma cells, and on the expression of upstream the non-steroidal anti-inflammatory drug (NSAID)-activated genes NAG1, NFKBIA, MYD88, and RELA, as well as at the chemokine profiling in colorectal tumors. Meloxicam downregulated CCL4 9.9-fold, but otherwise the classic oxicams had a negligible/non-significant effect. Novel analogues with a thiazine ring substituted with arylpiperazine and benzoyl moieties significantly modulated chemokine expression to varying degree, upregulated NAG1 and NFKBIA, and downregulated MYD88. They inhibited CCL3 and CCL4, and their effect on CCL2 and CXCL2 depended on the dose and exposure. The propylene linker between thiazine and piperazine nitrogens and one arylpiperazine fluorine substituent characterized the most effective analogue. Only CCL19 and CXCL2 were not upregulated in tumors, nor was CXCL2 in tumor-adjacent tissue compared to normal mucosa. Compared to adjacent tissue, CCL4 and CXCL2 were upregulated, while CCL2, CCL8, and CCL19 were downregulated in tumors. Tumor CCL2 and CCL7 increased along with advancing T and CCL3, and CCL4 along with the N stage. The introduction of arylpiperazine and benzoyl moieties into the oxicam scaffold yields effective modulators of chemokine expression, which act by upregulating NAG1 and interfering with NF-κB signaling.

C-C Motif Chemokine 8 promotes angiogenesis in vascular endothelial cells

OBJECTIVES

Angiogenesis is an important progress associated with several pathological situations. Several chemokines have been reported to act as regulators of angiogenesis. The current study aimed to find whether C-C Motif Chemokine 8 is involved in angiogenesis regulation.

METHODS

To verify whether C-C Motif Chemokine 8 is related to angiogenesis in plaques, carotid plaques were collected from patients with severe carotid stenosis and analysed using CD31 immunohistochemistry and real-time PCR. To further clarify the relation between C-C Motif Chemokine 8 and angiogenesis, human umbilical vein endothelium cells and human dermal microvascular endothelial cells were treated with C-C Motif Chemokine 8 in the presence or absence of C-C motif chemokine receptor 2-Ab and extracellular regulated MAP kinase 1/2 inhibition (FR180204). Proliferation and migration of human umbilical vein endothelium cells and human dermal microvascular endothelial cells were examined with Cell Counting Kit-8 and Transwell chamber assay, respectively. In vitro angiogenesis stimulated by C-C Motif Chemokine 8 was examined using tube formation assay. Ex vivo and in vivo angiogenesis were assessed by mice aortic ring assay and Matrigel plug assay, respectively. C-C motif chemokine receptors of human umbilical vein endothelium cells were examined with real-time PCR, and C-C motif chemokine receptor 1, C-C motif chemokine receptor 2, extracellular regulated MAP kinase 1/2 and phosphorylation-extracellular regulated MAP kinase 1/2 were examined with western blotting assay.

RESULTS

C-C Motif Chemokine 8 was increased in carotid plaques with severe angiogenesis in both RNA and protein level. C-C Motif Chemokine 8 (5 ng/ml) weakly increased human umbilical vein endothelium cell proliferation, but not on human dermal microvascular endothelial cells. Migration and tube formation could be induced by C-C Motif Chemokine 8 in both human umbilical vein endothelium cells and human dermal microvascular endothelial cells. In mice aortic ring assay and Matrigel plug assay, C-C Motif Chemokine 8 could promote angiogenesis compared to vehicle groups. Phosphorylation of extracellular regulated MAP kinase 1/2 was increased with C-C Motif Chemokine 8 stimulation. The migration and tube formation promoted by C-C Motif Chemokine 8 could be largely blocked by C-C motif chemokine receptor 2-Ab or extracellular regulated MAP kinase 1/2 inhibition (FR180204).

CONCLUSIONS

C-C Motif Chemokine 8 could promote both in vitro and in vivo angiogenesis. C-C motif chemokine receptor 2 played an important role in the activation of C-C Motif Chemokine 8 and extracellular regulated MAP kinase 1/2 signalling pathway was involved in this mechanism.

The CC and CXC chemokines: major regulators of tumor progression and the tumor microenvironment

Chemokines are a family of soluble cytokines that act as chemoattractants to guide the migration of cells, in particular of immune cells. However, chemokines are also involved in cell proliferation, differentiation, and survival. Chemokines are associated with a variety of human diseases including chronic inflammation, immune dysfunction, cancer, and metastasis. This review discusses the expression of CC and CXC chemokines in the tumor microenvironment and their supportive and inhibitory roles in tumor progression, angiogenesis, metastasis, and tumor immunity. We also specially focus on the diverse roles of CXC chemokines (CXCL9-11, CXCL4 and its variant CXCL4L1) and their two chemokine receptor CXCR3 isoforms, CXCR3-A and CXCR3-B. These two distinct isoforms have divergent roles in tumors, either promoting (CXCR3-A) or inhibiting (CXCR3-B) tumor progression. Their effects are mediated not only directly in tumor cells but also indirectly via the regulation of angiogenesis and tumor immunity. A full comprehension of their mechanisms of action is critical to further validate these chemokines and their receptors as biomarkers or therapeutic targets in cancer.

Acute Myeloid Leukemia and the Bone Marrow Niche-Take a Closer Look

The bone marrow is the home of hematopoiesis and is therefore a hotspot for the development of hematopoietic diseases. Complex interactions between the bone marrow microenvironment and hematopoietic stem cells must find a balance between proliferation, differentiation and homeostasis of the stem cell compartment. Changes in this tightly regulated network can provoke malignant transformation, leading to hematopoietic diseases. Here we focus on acute myeloid leukemia (AML), since this is the most frequent acute leukemia in adulthood with very poor overall survival rates and where relapse after chemotherapy continues to be a major challenge, driving demand for new therapeutic strategies. Current research is focusing on the identification of specific interactions between leukemic blasts and their niche components, which may be exploited as novel treatment targets along with induction chemotherapy. Significant progress has been gained over the last few years in the field of high-resolution imaging. Confocal ex vivo and intravital microscopy have revealed a detailed map of bone marrow structures and components; as well as identifying numerous alterations in the stem cell niche that correspond to disease progression. However, the underlying mechanisms are still not completely understood and due to the complexity, their elucidation remains a challenging. This review discusses the constitution of the AML niche in the bone marrow, the improvement in visualization of the complex three-dimensional niche structures and points out new therapeutic strategies to increase the overall survival of AML patients.

A Novel Image Probing System for Precise Quantification of Angiogenesis

The rapid development of clinical diagnostic imaging technology, in tandem with medical and angiogenesis research, has led to some major advances in healthcare. The chorioallantoic membrane assay is commonly used for studying normal angiogenesis as well as putative angiogenic and antiangiogenic substances. Despite the progress, it is generally recognized that a major problem is the lack of a suitable quantitative bioassay for angiogenesis. Image probing is a novel solution to this problem, which, together with its associated discipline of evaluating angiogenesis, is showing great potential not only for accurate measurement of even very small blood vessels but also for detailed three-dimensional quantification of blood vessels and surface characterization. This technique could be a helpful tool for quantification in angiogenesis research.

Inhibition of Endosteal Vascular Niche Remodeling Rescues Hematopoietic Stem Cell Loss in AML

Bone marrow vascular niches sustain hematopoietic stem cells (HSCs) and are drastically remodeled in leukemia to support pathological functions. Acute myeloid leukemia (AML) cells produce angiogenic factors, which likely contribute to this remodeling, but anti-angiogenic therapies do not improve AML patient outcomes. Using intravital microscopy, we found that AML progression leads to differential remodeling of vasculature in central and endosteal bone marrow regions. Endosteal AML cells produce pro-inflammatory and anti-angiogenic cytokines and gradually degrade endosteal endothelium, stromal cells, and osteoblastic cells, whereas central marrow remains vascularized and splenic vascular niches expand. Remodeled endosteal regions have reduced capacity to support non-leukemic HSCs, correlating with loss of normal hematopoiesis. Preserving endosteal endothelium with the small molecule deferoxamine or a genetic approach rescues HSCs loss, promotes chemotherapeutic efficacy, and enhances survival. These findings suggest that preventing degradation of the endosteal vasculature may improve current paradigms for treating AML.

Association of high expression of Groβ with clinical and pathological characteristics of unfavorable prognosis in gastrointestinal stromal tumors

GROβ (CXCL2) is a chemokine produced by endotoxin-treated macrophages that mediates inflammation and tumor development. However, little is known about GROβ expression in gastrointestinal stromal tumors (GIST) or the relationship between GROβ expression and clinical attributes of GIST. GROβ expression was examined via immunohistochemical staining of 173 GIST samples using tissue microarray. The relationship between GROβ expression and relevant patient and tumor characteristics was assessed, using chi-square tests. Univariate and multivariate analysis was carried out using the Cox regression method. High GROβ cytoplasm staining was detected in 56 (32.4%) specimens; high GROβ nuclear staining was detected in 64 (37.0%) specimens. High GROβ cytoplasm staining was significantly associated with patients' age (P = 0.043) and tumor location (P = 0.014), while high GROβ nucleus staining was significantly associated with mitotic index (P = 0.034), tumor location (P = 0.049), and AFIP-Miettinen risk classification (P = 0.048). Kaplan-Meier survival curves showed GIST patients with low GROβ cytoplasm expression (P = 0.023) and mitotic index < 6 per 50 HPFs (P = 0.026) to have a more favorable prognosis. These findings indicate that GROβ expression correlates with malignant GIST phenotypes and could be an unfavorable prognostic marker in patients with GIST.

Serum GROβ: a potential tumor-associated biomarker for colorectal cancer

OBJECTIVE

This study aimed to confirm the potential of growth-related gene product β (GROβ) as a biomarker for colorectal cancer. We compared serum GROβ levels in patients with colorectal cancer, healthy individuals and individuals with non-tumor diseases.

METHODS

We measured serum GROβ levels with enzyme-linked immunosorbent assay in patients with colorectal cancer (123 preoperative samples and 66 postoperative samples), 88 healthy controls and 125 individuals with other diseases. Serum levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were measured in all samples with an immunoluminometric assay. Statistical analyses were performed to determine associations between serum GROβ levels and clinical parameters for colorectal cancer. A receiver operating characteristic (ROC) curve was analyzed for GROβ, CEA and CA19-9.

RESULTS

The serum GROβ levels were much higher in patients with colorectal cancer (median: 96.15 pg/ml) than those in healthy controls (median: 43.28 pg/ml, P < 0.01) and other disease controls (median: 57.30 pg/ml, P < 0.01). Serum GROβ levels in colorectal cancer were correlated positively with tumor-node-metastasis staging (P < 0.01) and the depth of infiltration (P < 0.05), but not with the histological grade, tumor embolus, lymph node metastasis, gross pathologic tumor type, or patient gender. The sensitivity and specificity of the assay for serum GROβ were 56.1% (69/123) and 95.31% (203/213), respectively. The area under the ROC curve constructed with GROβ (0.834) was larger than that constructed with CEA (0.739) or CA19-9 (0.676) for discriminating colorectal cancer from matched controls.

CONCLUSION

These preliminary results suggested that the serum GROβ level could be a useful biomarker for colorectal cancer diagnoses.

The CXCL7/CXCR1/2 axis is a key driver in the growth of clear cell renal cell carcinoma

Mutations in the von Hippel-Lindau gene upregulate expression of the central angiogenic factor VEGF, which drives abnormal angiogenesis in clear cell renal cell carcinomas (ccRCC). However, the overexpression of VEGF in these tumors was not found to correlate with overall survival. Here, we show that the proangiogenic, proinflammatory cytokine CXCL7 is an independent prognostic factor for overall survival in this setting. CXCL7 antibodies strongly reduced the growth of ccRCC tumors in nude mice. Conversely, conditional overexpression of CXCL7 accelerated ccRCC development. CXCL7 promoted cell proliferation in vivo and in vitro, in which expression of CXCL7 was induced by the central proinflammatory cytokine interleukin (IL)-1β. ccRCC cells normally secrete low amounts of CXCL7; it was more highly expressed in tumors due to high levels of IL-1β there. We found that a pharmacological inhibitor of the CXCL7 receptors CXCR1 and CXCR2 (SB225002) was sufficient to inhibit endothelial cell proliferation and ccRCC growth. Because CXCR1 and CXCR2 are present on both endothelial and ccRCC cells, their inhibition affected both the tumor vasculature and the proliferation of tumor cells. Our results highlight the CXCL7/CXCR1/CXCR2 axis as a pertinent target for the treatment of ccRCC.

CXCR3, a double-edged sword in tumor progression and angiogenesis

CXC chemokines are involved in chemotaxis, regulation of cell growth, induction of apoptosis and modulation of angiostatic effects. CXCL9, CXCL10, CXCL11, CXCL4 and its variant CXCL4L1 are members of the CXC chemokine family, which bind to the CXCR3 receptor to exert their biological effects. These chemokines are associated with a variety of human diseases including chronic inflammation, immune dysfunction, cancer and metastasis. In this review, we focus on accumulating evidence demonstrating the pivotal role of CXCR3 in tumor progression. Its effects are mediated directly in tumor cells or indirectly through the regulation of angiogenesis and tumor immunity. Understanding the emerging role of CXCR3 and its signaling mechanisms further validates this receptor as a biomarker and therapeutic target for tumor progression and tumor angiogenesis.

The role of chemokines and their receptors in angiogenesis

Chemokines are a vertebrate-specific group of small molecules that regulate cell migration and behaviour in diverse contexts. So far, around 50 chemokines have been identified in humans, which bind to 18 different chemokine receptors. These are members of the seven-transmembrane receptor family. Initially, chemokines were identified as modulators of the immune response. Subsequently, they were also shown to regulate cell migration during embryonic development. Here, we discuss the influence of chemokines and their receptors on angiogenesis, or the formation of new blood vessels. We highlight recent advances in our understanding of how chemokine signalling might directly influence endothelial cell migration. We furthermore examine the contributions of chemokine signalling in immune cells during this process. Finally, we explore possible implications for disease settings, such as chronic inflammation and tumour progression.

Profile of lipid and protein autacoids in diabetic vitreous correlates with the progression of diabetic retinopathy

OBJECTIVE

This study was aimed at obtaining a profile of lipids and proteins with a paracrine function in normal and diabetic vitreous and exploring whether the profile correlates with retinal pathology.

RESEARCH DESIGN AND METHODS

Vitreous was recovered from 47 individuals undergoing vitreoretinal surgery: 16 had nonproliferative diabetic retinopathy (NPDR), 15 had proliferative diabetic retinopathy, 7 had retinal detachments, and 9 had epiretinal membranes. Protein and lipid autacoid profiles were determined by protein arrays and mass spectrometry-based lipidomics.

RESULTS

Vitreous lipids included lipoxygenase (LO)- and cytochrome P450 epoxygenase (CYP)-derived eicosanoids. The most prominent LO-derived eicosanoid was 5-hydroxyeicosate traenoic acid (HETE), which demonstrated a diabetes-specific increase (P = 0.027) with the highest increase in NPDR vitreous. Vitreous also contained CYP-derived epoxyeicosatrienoic acids; their levels were higher in nondiabetic than diabetic vitreous (P < 0.05). Among inflammatory, angiogenic, and angiostatic cytokines and chemokines, only vascular endothelial growth factor (VEGF) showed a significant diabetes-specific profile (P < 0.05), although a similar trend was noted for tumor necrosis factor (TNF)-alpha. Soluble VEGF receptors R1 and R2 were detected in all samples with lowest VEGF-R2 levels (P < 0.05) and higher ratio of VEGF to its receptors in NPDR and PDR vitreous.

CONCLUSIONS

This study is the first to demonstrate diabetes-specific changes in vitreous lipid autacoids including arachidonate and docosahexanoate-derived metabolites indicating an increase in inflammatory versus anti-inflammatory lipid mediators that correlated with increased levels of inflammatory and angiogenic proteins, further supporting the notion that inflammation plays a role the pathogenesis of this disease.

Differential expression of the chemokines GRO-2, GRO-3, and interleukin-8 in colon cancer and their impact on metastatic disease and survival

BACKGROUND AND AIM

Chemotactic cytokines play a role in angiogenesis and attraction of immune cells. However, their contribution to tumor formation remains incompletely understood. In a previous transcriptome study, we identified a family of structurally related chemokines of the CXC-family to be specifically up-regulated in colorectal cancer. The aim of the present study was to investigate the regulation of their expression in colon cancer cells and to test the hypothesis that altered CXC-chemokine expression is related to critical clinical parameters, such as survival or metastasis formation.

MATERIALS AND METHODS

Expression levels of interleukin-8 (CXCL-8) and growth-related oncogenes 2 and 3 (GRO-2/CXCL-2 and GRO-3/CXCL-3) were quantified using qRT-PCR in 97 patients with completely resected colon carcinoma and correlated with clinical parameters. Moreover, 16 samples of normal mucosa, nine samples of benign adenoma, and 11 samples of liver metastasis were analyzed. Next, the regulation of chemokine expression in response to various stimuli was tested in colon cancer cell lines (HT29, HCT116, CaCO2).

RESULTS

Expression of GRO-2, GRO-3, and IL-8 was significantly increased in colon cancer as compared to normal colon tissue. Expression of GRO-2 and GRO-3 was already enhanced in premalignant adenomas, and GRO-3 was significantly down-regulated in liver metastasis as compared to the primary tumor. Importantly, expression of GRO-3 was significantly higher in patients with local versus systemic disease. Moreover, IL-8 expression was significantly associated to overall post-operative survival. Finally, all chemokines were strongly induced by IL-1alpha in the colon cancer cell lines tested, indicating a potential link to inflammatory processes.

CONCLUSION

In accordance with earlier findings, we report here a significantly increased expression of GRO-2, GRO-3, and IL-8 in colon carcinoma as compared to normal tissue. Furthermore, GRO-3 was related to metastasis formation, and IL-8 was associated with survival, suggesting a potential predictive power of these markers.

The Chick Embryo Chorioallantoic Membrane as an In Vivo Assay to Study Antiangiogenesis

Antiangiogenesis, e.g., inhibition of blood vessel growth, is being investigated as a way to prevent the growth of tumors and other angiogenesis-dependent diseases. Pharmacological inhibition interferes with the angiogenic cascade or the immature neovasculature with synthetic or semi-synthetic substances, endogenous inhibitors or biological antagonists.The chick embryo chorioallantoic membrane (CAM) is an extraembryonic membrane, which serves as a gas exchange surface and its function is supported by a dense capillary network. Because its extensive vascularization and easy accessibility, CAM has been used to study morphofunctional aspects of the angiogenesis process in vivo and to study the efficacy and mechanism of action of pro- and anti-angiogenic molecules. The fields of application of CAM in the study of antiangiogenesis, including our personal experience, are illustrated in this review article.

Regression of human pancreatic tumor xenografts in mice after a single systemic injection of recombinant vaccinia virus GLV-1h68

Oncolytic virotherapy of tumors has shown promising results in both preclinical and clinical studies. Here, we investigated the therapeutic efficacy of a replication-competent vaccinia virus, GLV-1h68, against human pancreatic carcinomas in cell cultures and in nude mice. We found that GLV-1h68 was able to infect, replicate in, and lyse tumor cells in vitro. Virus-mediated marker gene expressions were readily detected. Moreover, s.c. PANC-1 pancreatic tumor xenografts were effectively treated by a single i.v. dose of GLV-1h68. Cancer killing was achieved with minimal toxicity. Viral titer analyses in homogenized organs and PANC-1 tumors showed that the mutant virus resides almost exclusively in the tumors and not in healthy organs. Except mild spleen enlargements, no histopathology changes were observed in any other organs 2 months after virus injection. Surprisingly, s.c. MIA PaCa-2 pancreatic tumors were treated with similar efficiency as PANC-1 tumors, although they differ significantly in sensitivity to viral lysis in cell cultures. When GLV-1h68 oncolytic viral therapy was used together with cisplatin or gemcitabine to treat PANC-1 tumors, the combination therapy resulted in enhanced and accelerated therapeutic results compared with the virus treatment alone. Profiling of proteins related to immune response revealed a significant proinflammatory immune response and marked activation of innate immunity in virus-colonized tumors. In conclusion, the GLV-1h68 strain showed outstanding therapeutic effects and a documented safety profile in mice, with great promise for future clinical development.

A systematic methodology for proteome-wide identification of peptides inhibiting the proliferation and migration of endothelial cells

We introduce a systematic computational methodology based on bioinformatics that has enabled us to identify and classify >120 endogenous peptide inhibitors of endothelial cell proliferation and migration. These peptides are derived from members of the type IV collagen, thrombospondin, and CXC chemokine protein families, as well as somatotropin hormones, serpins, and various kringle-containing proteins. Their activity in suppressing the proliferation and migration of endothelial cells in vitro provides proof of principle for the validity of this computational method. Interestingly, some of the peptides are derived from proteins known to be proangiogenic. By performing receptor neutralization studies, we have identified receptors to which these peptides bind. On the basis of this receptor-binding information, we evaluated several examples of peptide-based combinatorial screening strategies. In some cases, this combinatorial screening identified strong synergism between peptides. The current work provides a guideline for a computational-based peptidomics approach for the discovery of endogenous bioactive peptides.

Effect of mini-tyrosyl-tRNA synthetase on ischemic angiogenesis, leukocyte recruitment, and vascular permeability

Mini-tyrosyl-tRNA synthetase (mini-TyrRS), the N-terminal domain of tyrosyl-tRNA synthetase, is a recently identified protein released by endothelial cells that exhibits angiogenic and leukocyte chemoattractant, ELR-motif (Glu-Leu-Arg)-dependent activities in vitro. We sought to determine whether exogenous mini-TyrRS exerts these and other cytokine-like actions in physiological and pathological settings in vivo. High-dose mini-TyrRS (600 microg.kg(-1).day(-1)) augmented while low-dose mini-TyrRS (3 microg.kg(-1).day(-1)), unexpectedly, inhibited angiogenesis in the ischemic mouse ear. Enhanced angiogenesis was associated with increased CD45- and CD4-positive leukocyte accumulation. Mini-TyrRS also had biphasic actions on both basal and mustard oil-evoked and VEGF-evoked leakage of Evan's blue dye-albumin in nonischemic ear and in endothelial cell monolayers, that is, low-dose inhibited and high-dose augmented leakage. Mutation of the ELR motif of mini-TyrRS abolished the above activities. Mini-TyrRS was reduced (immunoblot) in extracts of ischemic calf muscle and in thoracic aorta explants exposed to hypoxia or VEGF. Inhibition of VEGF with a soluble Flt1 "trap" protein abolished this hypoxic-induced reduction in mini-TyrRS in aorta explants. These data show that mini-TyrRS has dose-dependent biphasic effects on ischemic angiogenesis and vascular permeability in vivo, that is, antiangiogenic and antipermeability activities at low concentration and proangiogenic, propermeability activities at high concentrations.

Novel anti-angiogenic peptides derived from ELR-containing CXC chemokines

Angiogenesis is tightly regulated by numerous endogenous pro- and anti-angiogenic proteins and peptides. Among these are the CXC chemokines, a set of multifunctional peptides. CXC chemokines containing the ELR motif act as pro-angiogenic agents by regulating both endothelial cell proliferation and migration. Here we show that a set of six 22-24-amino acid peptides derived from the pro-angiogenic ELR-containing CXC chemokines exhibit notable anti-proliferative and anti-migratory activity in vitro; we call these peptides chemokinostatins. The ability of the identified peptides to inhibit the basic components of angiogenesis even though they are derived from pro-angiogenic proteins contributes towards the understanding of the diverse role of the CXC chemokine family in angiogenesis.

Mullerian-inhibiting substance induces Gro-beta expression in breast cancer cells through a nuclear factor-kappaB-dependent and Smad1-dependent mechanism

Mullerian-inhibiting substance (MIS), a transforming growth factor-beta family member, activates the nuclear factor-kappaB (NF-kappaB) pathway and induces the expression of B-cell translocation gene 2 (BTG2), IFN regulatory factor-1 (IRF-1), and the chemokine Gro-beta. Inhibiting NF-kappaB activation with a phosphorylation-deficient IkappaBalpha mutant abrogated MIS-mediated induction of all three genes. Expression of dominant-negative Smad1, in which serines at the COOH-terminal SSVS motif are converted to alanines, suppressed MIS-induced Smad1 phosphorylation and impaired MIS-stimulated Gro-beta promoter-driven reporter expression and Gro-beta mRNA. Suppressing Smad1 expression using small interfering RNA also mitigated MIS-induced Gro-beta mRNA, suggesting that regulation of Gro-beta expression by MIS was dependent on activation of NF-kappaB as well as Smad1. However, induction of IRF-1 and BTG2 mRNAs by MIS was independent of Smad1 activation. Characterization of kappaB-binding sequences within Gro-beta, BTG2, and IRF-1 promoters showed that MIS stimulated binding of p50 and p65 subunits to all three sites, whereas phosphorylated Smad1 (phospho-Smad1) protein was detectable only in the NF-kappaB complex bound to the kappaB site of the Gro-beta promoter. Consistent with these observations, chromatin immunoprecipitation assays showed recruitment of both phospho-Smad1 and p65 to the Gro-beta promoter in vivo, whereas p65, but not phospho-Smad1, was recruited to the BTG2 promoter. These results show a novel interaction between MIS-stimulated Smad1 and NF-kappaB signaling in which enhancement of NF-kappaB DNA binding and gene expression by phospho-Smad1 is dependent on the sequence of the kappaB consensus site within the promoter.

Coincident activation of Th2 T cells with onset of the disease and differential expression of GRO-gamma in peripheral blood leukocytes in minimal change disease

BACKGROUND

Involvement of Th2 T cells/NFkappaB in minimal change disease (MCD) has been postulated. A promising but unconfirmed glomerular permeability factor (GPF) from MCD T cells has been described. We explored whether GPF was the consequence of Th2 cell activation.

METHODS

Peripheral blood leukocytes (PBL) from 16 MCD patients and 7 normal controls were analyzed and the results were statistically compared.

RESULTS

Flow cytometry demonstrated a significant expansion of CD4+ T cell population and dramatically increased CD69+ cells among CD4+ T cells in MCD, suggesting coincident activation of T cells with onset of the disease. RT-PCR on RNA from either freshly isolated PBL or post in vitroactivation showed high-level expression of the Th2 cytokine interleukin-4 in all MCD patients. Importantly, both antibody microarray assay on sera and RT-PCR on mRNA of PBL revealed expression of a CXC chemokine GRO-gamma (growth-related oncogene) in all MCD patients as compared with one of 7 controls.

CONCLUSIONS

Our results reveal an association between onset of MCD and activation of Th2 cells. The GRO family has been implicated in the function of endothelial cells, and its expression is under NFkappaB regulation. Thus, GRO-gamma is a promising candidate for Th2-associated GPF in MCD.

CCL2 Regulates Angiogenesis via Activation of Ets-1 Transcription Factor

Although recent studies have suggested that CC chemokine CCL2 may directly affect the angiogenesis, the signaling events involved in such regulation remain to be determined. This study investigated a potential signal mechanism involved in CCL2-induced angiogenesis. Our in vitro and in vivo (hemangioma model of angiogenesis) experiments confirmed earlier findings that CCL2 can induce angiogenesis directly. Using a gene array analysis, CCL2 was found to induce expression of several angiogenic factors in brain endothelial cells. Among the most prominent was an up-regulation in Ets-1 transcription factor. CCL2 induced a significant increase in Ets-1 mRNA and protein expression as well as Ets-1 DNA-binding activity. Importantly, Ets-1 antisense oligonucleotide markedly abrogated in vitro CCL2-induced angiogenesis, suggesting that Ets-1 is critically involved in this process. Activation of Ets-1 by CCL2 further regulated some of Ets-1 target molecules including beta(3) integrins. CCL2 induced significant up-regulation of beta(3) mRNA and protein expression, and this effect of CCL2 was prevented by the Ets-1 antisense oligonucleotide. The functional regulation of Ets-1 activity by CCL2 was dependent on ERK-1/2 cascade. Inhibition of ERK1/2 activity by PD98509 prevented CCL2-induced increases in Ets-1 DNA-binding activity and Ets-1 mRNA expression. Based on these findings, we suggest that Ets-1 transcription factor plays a critical role in CCL2 actions on brain endothelial cells and CCL2-induced angiogenesis.

Construction of recombinant eukaryotic expression vector for human endostatin and its expression in liver cancer cell line SMMC-7721

AIM: To construct the recombinant eukaryotic expression vector for human endostatin and express it in human liver cancer cell line SMMC-7721, and to observe its anti-angiogenesis activity in vitro.

METHODS: Human endostatin cDNA containing interleukin-2 (IL-2) secreting peptide was cloned into eukaryotic expression plasmid pcDNA3.0 to construct recombinant plasmid pCD-sEndo. The plasmid pCD-sEndo was transfected intoSMMC-7721 cells by cationic liposome. The positive cell clones were selected by G418 and named SMMC/sEndo. The expression of endostatin protein was analyzed by Western-blot. The activity of endostatin protein in the supernatant of SMMC/sEndo cells was explored by the angiogenesis experiment of chicken chorioallantoic membrane (CAM).

RESULTS: The eukaryotic expression vector pCD-sEndo was successfully constructed and was confirmed by enzyme digestion and sequence analysis. The endostatin protein was expressed in the supernatant of SMMC/sEndo cells, about 20 ku in size. No expression of endostatin protein was found in the control cells. There were fewer blood vessels in the CAM treated with endostatin protein, and the blood vessel density markedly decreased. Furthermore, the density decreased with the increase of endostatin protein.

CONCLUSION: The recombinant eukaryotic expression vector is correctly constructed. The human endostatin protein with the activity of anti-angiogenesis can be expressed and secreted in the supernatant of SMMC-7721 cells tranfected with pCD-sEndo.

Differential gene expression during capillary morphogenesis in a microcarrier-based three-dimensional in vitro model of angiogenesis with focus on chemokines and chemokine receptors

AIM

To globally compare the gene expression profiles during the capillary morphogenesis of human microvascular endothelial cells (HMVECs) in an in vitro angiogenesis system with affymetrix oligonucleotide array.

METHODS

A microcarrier-based in vitro angiogenesis system was developed, in which ECs migrated into the matrix, proliferated, and formed capillary sprouts. The sprouts elongated, branched and formed networks. The total RNA samples from the HMVECs at the selected time points (0.5, 24, and 72 h) during the capillary morphogenesis were used for microarray analyses, and the data were processed with the softwares provided by the manufacturers. The expression patterns of some genes were validated and confirmed by semi-quantitative RT-PCR. The regulated genes were grouped based on their molecular functions and expression patterns, and among them the expression of chemokines and chemokine receptors was specially examined and their functional implications were analyzed.

RESULTS

A total of 1 961 genes were up- or down-regulated two-folds or above, and among them, 468 genes were up- or down-regulated three-folds or above. The regulated genes could be grouped into categories based on their molecular functions, and were also clustered into six groups based on their patterns of expression. As for chemokines and chemokine receptors, CXCL1/GRO-alpha, CXCL2/GRO-beta, CXCL5/ENA-78, CXCL6/GCP2, IL-8/CXCL8, CXCL12/SDF-1, CXCL9/Mig, CXC11/ITAC, CX3CL1/fractalkine, CCL2/MCP-1, CCL3, CCL5/RANTES, CCL7, CCL15, CCL21, CCL23, CCL28, and CCR1, CCR9, CXCR4 were identified. Moreover, these genes demonstrated different changing patterns during the capillary morphogenesis, which implied that they might have different roles in the sequential process. Among the chemokines identified, CCL2/MCP-1, CCL5/RANTES and CX3CL1 were specially up-regulated at the 24-h time point when the sprouting characterized the morphological change. It was thus suggested that they might exert crucial roles at the early stage of angiogenesis.

CONCLUSION

The present study demonstrates a global profile of gene expression during endothelial capillary morphogenesis, and the results provide us much information about the molecular mechanisms of angiogenesis, with which further evaluation of individual genes can be conducted.

Constitutive expression of growth regulated oncogene (gro) in human colon carcinoma cells with different metastatic potential and its role in regulating their metastatic phenotype

The purpose of this study was to examine the expression and functional significance of the growth-regulated oncogene (gro) family in human colon carcinoma growth and metastasis. We examined constitutive expression of CXCL1 (gro-alpha), CXCL2 (gro-beta), CXCL3 (gro-gamma) and their receptor, CXCR2 in human colon carcinoma cells with different metastatic potentials. Non-metastatic and low metastatic cells expressed lower levels of CXCL1 and CXCR2 mRNA and protein as compared to high metastatic colon carcinoma cells. No difference in CXCL2 and CXCL3 mRNA expression levels was observed. Colon carcinoma cells expressing higher levels of CXCL1 exhibit increased proliferation and invasive potential. Furthermore, exogenous addition of recombinant human CXCL1 significantly enhanced the proliferation and invasiveness of colon carcinoma cells. Furthermore, treatment of KM12C cells with exogenous CXCL1 enhanced their invasiveness. Neutralizing antibody to CXCL1 in combination with antibody to CXCR2 inhibited highly metastatic KM12L4 (high CXCL1 expressor) cell proliferation. These data demonstrate that the constitutive expression of CXCL1 and its receptor CXCR2 is associated with metastatic potential and modulates colon cancer cell proliferation and an invasive phenotype.

Early events in HSV keratitis--setting the stage for a blinding disease

The last decade has seen herpes simplex virus (HSV)-induced stromal keratitis (SK) research shift from being a topic only of interest to vision researchers to one that fascinates the general field of inflammatory disease. Studies on experimental mouse lesions have uncovered several fundamental processes that explain lesion development. In this model, the chronic immuno-inflammatory lesions are mainly orchestrated by CD4+ T cells, but multiple early events occur that set the stage for the subsequent pathology. These include virus replication, the production of key cytokines and chemokines, neovascularization of the avascular cornea and the influx of certain inflammatory cell types. Many of these early events are subject to modulation, providing an approach to controlling this important cause of human blindness. We also comment on events ongoing during chronic SK, debating whether or not these represent virus-induced or autoimmune lesions.

Chemokine receptor antagonists: novel therapeutics for inflammation and AIDS

To date almost 40 human chemokines have been described, modulating a complex and overlapping set of biological activities important for basal leukocyte trafficking, as well as the extravasation and tissue infiltration of leukocytes in response to inciting agents. Chemokines appear to be key mediators in a number of inflammatory pathologies as a result of their chemotactic effects on almost every leukocyte type, including neutrophils, eosinophils, basophils, monocytes, dendritic cells, NK cells, B-cells and T-cells, together with their ability to stimulate effector functions, such as granule release and superoxide radical production from these cells. With the recent discovery that some chemokine receptors function as HIV-1 co-receptors and with accumulating evidence that chemokines may also regulate certain aspects of haematopoiesis, angiogenesis and apoptosis, the chemokines and their receptors have emerged as a new set of drug discovery targets for the pharmaceutical and biotechnology industry.

Gene regulation of a novel angiogenesis inhibitor, vasohibin, in endothelial cells

We recently reported that vasohibin is a negative feedback regulator of angiogenesis, and it is specifically expressed in endothelial cells. Here, we characterize the regulation of vasohibin expression. Two possible splicing variants were found, and the longer isoform was preferentially expressed. VEGF induced the expression of vasohibin, and this induction was abrogated by anti-VEGFR2 mAb but not by anti-VEGFR1 mAb. Pharmacological analysis revealed that the downstream targets of VEGFR2 were PKCs, especially PKCdelta. Actinomycin D did not alter the kinetics of vasohibin mRNA induction upon VEGF treatment, whereas cycloheximide completely abolished its induction. We tested the effect of various inflammatory cytokines on vasohibin expression. TNFalpha, IL1 and IFNgamma decreased VEGF-stimulated vasohibin expression. Actinomycin D did not alter the kinetics of vasohibin mRNA induction upon TNFalpha treatment. These results indicate that the expression of vasohibin in endothelial cells is regulated either positively or negatively by certain factors at the transcriptional level.

Vasohibin as an endothelium-derived negative feedback regulator of angiogenesis

Negative feedback is a crucial physiological regulatory mechanism, but no such regulator of angiogenesis has been established. Here we report a novel angiogenesis inhibitor that is induced in endothelial cells (ECs) by angiogenic factors and inhibits angiogenesis in an autocrine manner. We have performed cDNA microarray analysis to survey VEGF-inducible genes in human ECs. We characterized one such gene, KIAA1036, whose function had been uncharacterized. The recombinant protein inhibited migration, proliferation, and network formation by ECs as well as angiogenesis in vivo. This inhibitory effect was selective to ECs, as the protein did not affect the migration of smooth muscle cells or fibroblasts. Specific elimination of the expression of KIAA1036 in ECs restored their responsiveness to a higher concentration of VEGF. The expression of KIAA1036 was selective to ECs, and hypoxia or TNF-alpha abrogated its inducible expression. As this molecule is preferentially expressed in ECs, we designated it "vasohibin." Transfection of Lewis lung carcinoma cells with the vasohibin gene did not affect the proliferation of cancer cells in vitro, but did inhibit tumor growth and tumor angiogenesis in vivo. We propose vasohibin to be an endothelium-derived negative feedback regulator of angiogenesis.

Chemokines in joint disease: the key to inflammation?

Targeting chemokines and/or chemokine receptors appears to be an intriguing new approach to treating chronic inflammatory disorders like rheumatoid arthritis, inflammatory bowel diseases, multiple sclerosis, and transplant rejections. The involvement of chemokines and chemokine receptors in inflammatory joint diseases, the in vitro and in vivo characteristics of the chemokine family in inflammatory joint disease, and initial clinical data on chemokine blockade in patients with rheumatoid arthritis suggest that targeting the chemokine and chemokine receptor family might provide a new, promising antirheumatic strategy.

Role of chemokines in angiogenesis: CXCL12/SDF-1 and CXCR4 interaction, a key regulator of endothelial cell responses

Chemokines are small proteins that act as cell attractants via the activation of G protein-coupled receptors. Chemokines play an important role in several pathophysiological processes such as inflammation and immunity. Many proinflammatory chemokines also support the development of vascular blood supply at the site of inflammation. Similarly, tumor-generated chemokines can contribute to tumor growth by promoting angiogenesis. Recently, significant advances have been made in understanding the contribution of chemokines to the angiogenesis process. This review will discuss first the evidence supporting the direct contribution of different chemokine subfamily members, including CC, CXC, and CX3C chemokines, as positive or negative regulators of the angiogenesis process based on the expression of their cognate receptors on endothelial cells. Additionally, the relationship between classic angiogenic factors and chemokine receptor expression on endothelial cells, and the implications of chemokine production by cancer cells will be analyzed with particular emphasis on the CXCL12/stromal-cell derived factor-1 interaction with CXCR4.

Suppression of tumor growth by a new glycosaminoglycan isolated from the African giant snail Achatina fulica

Acharan sulfate is a new type of glycosaminoglycan from the giant African snail, Achatina fulica. Acharan sulfate, which has a primary repeating disaccharide structure of alpha-D-N-acetylglucosaminyl-2-O-sulfo-alpha-L-iduronic acid, was studied as a potential antitumor agent in both in vivo and in vitro assays. The antiangiogenic activity of acharan sulfate was evaluated in the chorioallantoic membrane assay and by measuring its effect on the proliferation of calf pulmonary artery endothelial cells. In vivo, a matrigel plug assay showed that acharan sulfate suppressed basic fibroblast growth factor (bFGF)-stimulated angiogenesis and lowered the hemoglobin (Hb) content inside the plug. Acharan sulfate was administered s.c. at two doses for 15 days to C57BL/6 mice implanted with murine Lewis lung carcinoma in the back. It was also administered i.p. to ICR mice bearing sarcoma 180 at a dose of 30 mg/kg. Subcutaneous injection of acharan sulfate at doses of 10 and 30 mg/kg decreased tumor weight and tumor volume by 40% without toxicity or resistance. Intraperitoneal injection of acharan sulfate also decreased tumor weight and volume by 40% in sarcoma 180-bearing mice. These results suggest that the antitumor activity of acharan sulfate may be related to the inhibition of angiogenesis.

Analysis of the role of chemokines in angiogenesis

Chemokines, a large family of inflammatory cytokines, have been shown to play a critical role in the regulation of angiogenesis during several pathophysiologic processes, such as tumor growth, wound healing and ischemia. Semiquantitative or quantitative angiogenesis assays are commonly utilized to screen the angiogenic or angiostatic activity of chemokines. These include in vitro endothelial cell activation assays and ex vivo or in vivo models of neovascularization. Chemokines may exert their regulatory activity on angiogenesis directly or as a consequence of leukocyte infiltration and/or the induction of growth factor expression. The effect of chemokines on endothelium can be assessed by performing in vitro assays on purified endothelial cell populations or by in vivo assays. Nevertheless, each model used to evaluate the angiogenic or angiostatic activity of a discrete factor has advantages and limitations. Thus, in order to avoid under- or overestimating the regulatory effect of chemokines on angiogenesis and to evaluate all aspects of the angiogenic process, multiple assays are usually performed. This review summarizes past and recent studies on chemokines as modulators of angiogenesis with particular emphasis on the methods currently used for the assessment of chemokine-mediated angiogenic or angiostatic responses.

Inhibition of prostate tumor angiogenesis by the tumor suppressor CEACAM1

We have previously shown that CEACAM1, a cell-adhesion molecule, acts as a tumor suppressor in prostate carcinoma. Expression of CEACAM1 in prostate cancer cells suppresses their growth in vivo. However, CEACAM1 has no effect on the growth of prostate cancer cells in vitro. This difference suggests that the antitumor effect of CEACAM1 may be due to inhibition of tumor angiogenesis, perhaps by increased secretion of antiangiogenic molecules from the cells. In this study, we have demonstrated that expression of CEACAM1 in DU145 prostate cancer cells induced the production of a factor or factors that specifically blocked the growth of endothelial but not epithelial cells. Conditioned medium from the CEACAM1-expressing cells but not control luciferase-expressing cells inhibited endothelial cell migration up a gradient of stimulatory vascular endothelial growth factor in vitro and inhibited corneal neovascularization induced by basic fibroblast growth factor in vivo. Moreover, conditioned medium from CEACAM1-expressing cells induced endothelial cell apoptosis in vitro. Only medium conditioned by CEACAM1 mutants that were able to suppress tumor growth in vivo could cause endothelial cell apoptosis. These observations suggest that CEACAM1-mediated tumor suppression in vivo is, at least in part, due to the ability of CEACAM1 to inhibit tumor angiogenesis.

Continuous intravascular secretion of endostatin in mice from transduced hematopoietic stem cells

Endostatin, a 20-kDa carboxy-terminal fragment of collagen XVIII, is the leading member of a class of physiologic inhibitors of angiogenesis with potent antitumor activity. Repeated subcutaneous administration of recombinant endostatin in mice led to permanent regression of established tumors to a microscopic dormant state and prompted the initiation of human clinical trials. However, a discrepancy remained unresolved: sustained tumor regression has only been observed with a non-soluble, precipitated form of recombinant endostatin produced in bacteria. To shed light on this question and establish a model of systemic anti-angiogenic gene therapy of cancer that may surmount obstacles in protein production and delivery, we transduced murine hematopoietic stem cells with a retrovirus encoding a secretable form of endostatin. Despite continuous, high-level secretion of endostatin in the vasculature of all transplanted mice, we detected neither inhibition of in vivo neoangiogenesis nor antitumor activity. Resolution of this paradox may come from human trials of endostatin now underway.

Role of chemokine SDF-1/PBSF and its receptor CXCR4 in blood vessel development

Chemokines are a family of small, structurally related molecules that regulate cell trafficking. We isolated a chemokine, stromal cell-derived factor/pre-B cell growth-stimulating factor (SDF-1/PBSF), as a molecule that stimulates the growth of B lymphocyte precursors and then found its multiple physiological functions in development. SDF-1/PBSF is essential for embryonic viability, B lymphopoiesis, bone marrow myelopoiesis, and cardiogenesis. Moreover, a primary physiologic receptor for SDF-1/PBSF is a seven-transmembrane G-protein-coupled receptor, CXCR4, that also functions as a coreceptor for strains of HIV-1. In recent years, we have shown that SDF-1/ PBSF and CXCR4 chemokine ligand receptor system is required for vascularization of the gastrointestinal tract by analyzing mice deficient in these molecules, thus defining a new signaling system for organ vascularization during embryogenesis.

The chemokine CXCL13 (BCA-1) inhibits FGF-2 effects on endothelial cells

Several chemokines, belonging to both the CXC and CC classes, act as positive or negative regulators of angiogenesis. We sought to investigate the role of CXCL13, B cell-attracting chemokine 1 (BCA-1), also known as B-lymphocyte chemoattractant (BLC), on endothelial cell functions. We tested the effect of CXCL13 on HUVEC chemotaxis and proliferation in the presence of fibroblast growth factor (FGF)-2 and found that such chemokine inhibits FGF-2-induced functions, while is not active by itself. To test whether other FGF-2-mediated biological activities may be affected, we evaluated the ability of CXCL13 to rescue HUVEC from starvation-induced apoptosis, as FGF-2 is a survival factor for endothelial cells, and found that CXCL13 partially inhibits such rescue. Multiple mechanisms may be responsible for these biological activities as CXCL13 displaces FGF-2 binding to endothelial cells, inhibits FGF-2 homodimerization, and induces the formation of CXCL13-FGF-2 heterodimers. Our data suggest that CXCL13 may modulate angiogenesis by interfering with FGF-2 activity.

The metastasis-associated Mts1(S100A4) protein could act as an angiogenic factor

The involvement of Mts1(S100A4), a small Ca(2+)-binding protein in tumor progression and metastasis had been demonstrated. However, the mechanism by which mts1(S100A4) promoted metastasis had not been identified. Here we demonstrated that Mts1(S100A4) had significant stimulatory effect on the angiogenesis. We detected high incidence of hemangiomas--benign tumors of vascular origin in aged transgenic mice ubiquitously expressing the mts1(S100A4) gene. Furthermore, the serum level of the Mts1(S100A4) protein increased with ageing. Tumors developed in Mts1-transgenic mice revealed an enhanced vascular density. We showed that an oligomeric, but not a dimeric form of the Mts1(S100A4) protein was capable of enhancing the endothelial cell motility in vitro and stimulate the corneal neovascularization in vivo. An oligomeric fraction of the protein was detected in the conditioned media as well as in human serum. The data obtained allowed us to conclude that mts1(S100A4) might induce tumor progression via stimulation of angiogenesis.

Molecular mechanisms of tumor angiogenesis and tumor progression

The formation of new blood vessels (angiogenesis) is crucial for the growth and persistence of primary solid tumors and their metastases. Furthermore, angiogenesis is also required for metastatic dissemination, since an increase in vascular density will allow easier access of tumor cells to the circulation. Induction of angiogenesis precedes the formation of malignant tumors, and increased vascularization seems to correlate with the invasive properties of tumors and thus with the malignant tumor phenotype. In the last few years, the discovery and characterization of tumor-derived angiogenesis modulators greatly contributed to our understanding of how tumors regulate angiogenesis. However, although angiogenesis appears to be a rate-limiting event in tumor growth and metastatic dissemination, a direct connection between the induction of angiogenesis and the progression to tumor malignancy is less well understood. In this review, we discuss the most recent observations concerning the modulation of angiogenesis and their implications in tumor progression, as well as their potential impact on cancer therapy.

MGSA/GRO-mediated melanocyte transformation involves induction of Ras expression

The MGSA/GRO protein is endogenously expressed in almost 70% of the melanoma cell lines and tumors, but not in normal melanocytes. We have previously demonstrated that over-expression of human MGSA/GROalpha, beta or gamma in immortalized murine melanocytes (melan-a cells) enables these cells to form tumors in SCID and nude mice. To examine the possibility that the MGSA/GRO effect on melanocyte transformation requires expression of other genes, differential display was performed. One of the mRNA's identified in the screen as overexpressed in MGSA/GRO transformed melan-a clones was the newly described M-Ras or R-Ras3 gene, a member of the Ras gene superfamily. Over-expression of MGSA/GRO upregulates M-Ras expression at both the mRNA and protein levels, and this induction requires an intact glutamine-leucine-arginine (ELR)-motif in the MGSA/GRO protein. Western blot examination of Ras expression revealed that K- and N-Ras proteins are also elevated in MGSA/GRO-expressing melan-a clones, leading to an overall increase in the amount of activated Ras. MGSA/GRO-expressing melan-a clones exhibited enhanced AP-1 activity. The effects of MGSA/GRO on AP-1 activation could be mimicked by over-expression of wild-type M-Ras or a constitutively activated M-Ras mutant in control melan-a cells as monitored by an AP-1-luciferase reporter, while expression of a dominant negative M-Ras blocked AP-1-luciferase activity in MGSA/GRO-transformed melan-a clones. In the in vitro transformation assay, over-expression of M-Ras mimicked the effects of MGSA/GRO by inducing cellular transformation in control melan-a cells, while over-expression of dominant negative M-Ras in MGSA/GROalpha-expressing melan-a-6 cells blocked transformation. These data suggest that MGSA/GRO-mediated transformation requires Ras activation in melanocytes.

Molecular cloning and characterization of a novel CXC chemokine macrophage inflammatory protein-2 gamma chemoattractant for human neutrophils and dendritic cells

Chemokines play important roles in leukocyte trafficking as well as function regulation. In this study, we described the identification and characterization of a novel CXC chemokine from a human dendritic cell (DC) cDNA library, the full-length cDNA of which contains an open reading frame encoding 111 aa with a putative signal peptide of 34 aa. This CXC chemokine shares greatest homology with macrophage inflammatory protein (MIP)-2alphabeta, hence is designated as MIP-2gamma. Mouse MIP-2gamma was identified by electrocloning and is highly homologous to human MIP-2gamma. Northern blotting revealed that MIP-2gamma was constitutively and widely expressed in most normal tissues with the greatest expression in kidney, but undetectable in most tumor cell lines except THP-1 cells. In situ hybridization analysis demonstrated that MIP-2gamma was mainly expressed by the epithelium of tubules in the kidney and hepatocytes in the liver. Although no detectable expression was observed in freshly isolated or PMA-treated monocytes, RT-PCR analysis revealed MIP-2gamma expression by monocyte-derived DC. Recombinant MIP-2gamma from 293 cells is about 9.5 kDa in size and specifically detectable by its polyclonal Ab developed by the immunization with its 6His-tagged fusion protein. The eukaryotically expressed MIP-2gamma is a potent chemoattractant for neutrophils, and weaker for DC, but inactive to monocytes, NK cells, and T and B lymphocytes. Receptor binding assays showed that MIP-2gamma does not bind to CXCR2. This implies that DC might contribute to the innate immunity through the production of neutrophil-attracting chemokines and extends the knowledge about the regulation of DC migration.

Human endothelial cells express CCR2 and respond to MCP-1: direct role of MCP-1 in angiogenesis and tumor progression

Although several CXC chemokines have been shown to induce angiogenesis and play roles in tumor growth, to date, no member of the CC chemokine family has been reported to play a direct role in angiogenesis. Here we report that the CC chemokine, monocyte chemotactic protein 1 (MCP-1), induced chemotaxis of human endothelial cells at nanomolar concentrations. This chemotactic response was inhibited by a monoclonal antibody to MCP-1. MCP-1 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and the matrigel plug assays. As expected, the angiogenic response induced by MCP-1 was accompanied by an inflammatory response. With the use of a rat aortic sprouting assay in the absence of leukocytic infiltrates, we ruled out the possibility that the angiogenic effect of MCP-1 depended on leukocyte products. Moreover, the direct effect of MCP-1 on angiogenesis was consistent with the expression of CCR2, the receptor for MCP-1, on endothelial cells. Assessment of supernatant from a human breast carcinoma cell line demonstrated the production of MCP-1. Treatment of immunodeficient mice bearing human breast carcinoma cells with a neutralizing antibody to MCP-1 resulted in significant increases in survival and inhibition of the growth of lung micrometastases. Taken together, our data indicate that MCP-1 can act as a direct mediator of angiogenesis. As a chemokine that is abundantly produced by some tumors, it can also directly contribute to tumor progression. Therefore, therapy employing antagonists of MCP-1 in combination with other inhibitors of angiogenesis may achieve more comprehensive inhibition of tumor growth.

Human endothelial cells express CCR2 and respond to MCP-1: direct role of MCP-1 in angiogenesis and tumor progression

Although several CXC chemokines have been shown to induce angiogenesis and play roles in tumor growth, to date, no member of the CC chemokine family has been reported to play a direct role in angiogenesis. Here we report that the CC chemokine, monocyte chemotactic protein 1 (MCP-1), induced chemotaxis of human endothelial cells at nanomolar concentrations. This chemotactic response was inhibited by a monoclonal antibody to MCP-1. MCP-1 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and the matrigel plug assays. As expected, the angiogenic response induced by MCP-1 was accompanied by an inflammatory response. With the use of a rat aortic sprouting assay in the absence of leukocytic infiltrates, we ruled out the possibility that the angiogenic effect of MCP-1 depended on leukocyte products. Moreover, the direct effect of MCP-1 on angiogenesis was consistent with the expression of CCR2, the receptor for MCP-1, on endothelial cells. Assessment of supernatant from a human breast carcinoma cell line demonstrated the production of MCP-1. Treatment of immunodeficient mice bearing human breast carcinoma cells with a neutralizing antibody to MCP-1 resulted in significant increases in survival and inhibition of the growth of lung micrometastases. Taken together, our data indicate that MCP-1 can act as a direct mediator of angiogenesis. As a chemokine that is abundantly produced by some tumors, it can also directly contribute to tumor progression. Therefore, therapy employing antagonists of MCP-1 in combination with other inhibitors of angiogenesis may achieve more comprehensive inhibition of tumor growth.

Decreased nitric oxide levels stimulate osteoclastogenesis and bone resorption both in vitro and in vivo on the chick chorioallantoic membrane in association with neoangiogenesis

High nitric oxide (NO) levels inhibit osteoclast (OC)-mediated bone resorption in vivo and in vitro, and nitrate donors protect against estrogen-deficient bone loss in postmenopausal women. Conversely, decreased NO production potentiates OC bone resorption in vitro and is associated with in vivo bone loss in rats and humans. Previously, we reported that bone sections from rats administered aminoguanidine (AG), a selective inhibitor of NO production via inducible NO synthase, exhibited both increased OC resorptive activity as well as greater numbers of OC. Here, we investigated further whether AG promoted osteoclastogenesis, in addition to stimulating mature OC function, using a modified in vivo chick chorioallantoic membrane (CAM) system and an in vitro chick bone marrow OC-like cell developmental model. AG, focally administered in small agarose plugs placed directly adjacent to a bone chip implanted on the CAM, dose-dependently elicited neoangiogenesis while stimulating the number, size, and bone pit resorptive activity of individual OC ectopically formed in vivo. In addition to enhancing OC precursor recruitment via neoangiogenesis, AG also exerted other vascular-independent effects on osteoclastogenesis. Thus, AG promoted the in vitro fusion and formation from bone marrow precursor cells of larger OC-like cells that contained more nuclei per cell and exhibited multiple OC differentiation markers. AG stimulated development was inversely correlated with declining medium nitrite levels. In contrast, three different NO donors each dose-dependently inhibited in vitro OC-like cell development while raising medium nitrite levels. Therefore, NO sensitively regulates OC-mediated bone resorption through affecting OC recruitment (angiogenesis), formation (fusion and differentiation), and bone resorptive activity in vitro and in vivo. Possibly, the stimulation of neoangiogenesis and OC-mediated bone remodeling via AG or other pro-angiogenic agents may find clinical applications in reconstructive surgery, fracture repair, or the treatment of avascular necrosis.

Selective inhibition of monocyte chemoattractant protein-1 gene expression in human embryonal kidney cells by specific triple helix-forming oligonucleotides

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that is expressed by a variety of tissue cells in response to inflammatory stimuli, such as IL-1beta, TNF-alpha, and IFN-gamma. A major function of MCP-1 is the recruitment and activation of monocytes and T lymphocytes. Overexpression of MCP-1 has been implicated in a number of diseases, including glomerulonephritis and rheumatoid arthritis, indicating that the modulation of MCP-1 activity and/or expression is a desired therapeutic strategy. In the present study, our aim was to test whether the MCP-1 expression could be inhibited at the transcriptional level using triple helix-forming oligonucleotides (TFOs). We designed a TFO targeted to the SP-1 binding site in the human MCP-1 gene promoter. Gel mobility shift assays demonstrated that the phosphodiester TFO formed a sequence-specific triplex with its dsDNA target with an EC50 of approximately 1.9 x 10(-7) M. The corresponding phosphorothioated oligonucleotide was also effective in this assay with an 8-fold higher EC50 value. Binding of the TFO to the target DNA prevented the binding of rSP-1 and of nuclear proteins in vitro. The TFO could also partially inhibit endogenous MCP-1 gene expression in cultured human embryonic kidney cells. Treatment of TNF-alpha-stimulated human embryonic kidney 293 cells with the TFO inhibited the secretion of MCP-1 in a dose-dependent manner (up to 45% at 5 microM oligonucleotide). The inhibition of MCP secretion was caused at the level of gene transcription, because MCP-1 mRNA levels in oligonucleotide-treated cells were also decreased by approximately 40%.