Matrix metalloproteinases and angiogenesis

Increased angiogenesis at the site of abdominal aortic aneurysm rupture

Abdominal aortic aneurysm (AAA) rupture is associated with elevated levels of matrix metalloproteinase (MMP). Medial neovascularization is a known characteristic of established AAAs and involves proteolytic degradation of extracellular matrix by MMPs to facilitate endothelial cell proliferation and migration. This study evaluated the extent of neovascularization in abdominal aortic aneurysm rupture. Results indicated upregulation of proangiogenic cytokines and increased medial neovascularization at the aneurysm rupture edge compared with paired aneurysm anterior sac. Further investigations into the role of angiogenesis in aneurysm rupture may open novel therapeutic avenues to prevent aneurysm rupture.

Interleukin-1β increases expression and activity of matrix metalloproteinase-2 in cardiac microvascular endothelial cells: role of PKCα/β1and MAPKs

Matrix metalloproteinases (MMPs), a family of extracellular endopeptidases, are implicated in angiogenesis because of their ability to selectively degrade components of the extracellular matrix. Interleukin-1β (IL-1β), increased in the heart post-myocardial infarction (post-MI), plays a protective role in the pathophysiology of left ventricular (LV) remodeling following MI. Here we studied expression of various angiogenic genes affected by IL-1β in cardiac microvascular endothelial cells (CMECs) and investigated the signaling pathways involved in the regulation of MMP-2. cDNA array analysis of 96 angiogenesis-related genes indicated that IL-1β modulates the expression of numerous genes, notably increasing the expression of MMP-2, not MMP-9. RT-PCR and Western blot analyses confirmed increased expression of MMP-2 in response to IL-1β. Gelatin in-gel zymography and Biotrak activity assay demonstrated that IL-1β increases MMP-2 activity in the conditioned media. IL-1β activated ERK1/2, JNKs, and protein kinase C (PKC), specifically PKCα/β1, and inhibition of these cascades partially inhibited IL-1β-stimulated increases in MMP-2. Inhibition of PKCα/β1failed to inhibit ERK1/2. However, concurrent inhibition of PKCα/β1and ERK1/2 almost completely inhibited IL-1β-mediated increases in MMP-2 expression. Inhibition of p38 kinase and nuclear factor-κB (NF-κB) had no effect. Pretreatment with superoxide dismutase (SOD) mimetic, MnTMPyP, increased MMP-2 protein levels, whereas pretreatment with SOD and catalase mimetic, EUK134, partially inhibited IL-1β-stimulated increases in MMP-2 protein levels. Exogenous H2O2significantly increased MMP-2 protein levels, whereas superoxide generation by xanthine/xanthine oxidase had no effect. This in vitro study suggests that IL-1β modulates expression and activity of MMP-2 in CMECs.

Effects of stenting the parent artery on aneurysm filling and gene expression of various potential factors involved in healing of experimental aneurysms

SUMMARY

Intracranial stents are increasingly used in the endovascular treatment of aneurysms, but very little is known regarding their effect on the cellular and molecular evolution of aneurysms. Bilateral venous pouch lateral wall carotid aneurysms were created in 20 dogs. All dogs then underwent angiography and balloon-expandable stenting of one aneurysm four to six weeks later. Fifteen dogs underwent aneurysm harvesting at one day (n=3), four days (n=4), seven days (n=3), and 14 days (n=5) for mRNA expression analysis, using axial sections taken from the aneurysm neck and fundus for RTPCR amplification of four cytokines or growth factors: TNF-a, TGF-b1, MCP-1, and PDGFBB; two adhesion molecules: VCAM-1 and PECAM-1; five matrix modifying agents; MMP- 2, 9, TIMPs 1, 3, 4, and two cellular markers: CD34 and a-SMA. Five other dogs, sacrificed at 12 weeks, were examined for extent of filling of the aneurysm neck with organized tissue and for neointima formation at the aneurysm ostium. Angiography was performed prior to sacrifice in all animals, and compared with initial studies. Eleven out of 20 stented aneurysms showed a favorable angiographic evolution, while none of the 20 nonstented aneurysms improved (p=0.001). Pathology showed partially occluded aneurysms, with neointima formation around the stent struts.Observed trends in mRNA expression, that stenting increased expression of genes involved in organization and neointima formation, agreed with experimental hypotheses, but differences between stented and non-stented aneurysms did not reach statistical significance. Parent vessel stenting was associated with angiographic improvement of aneurysm appearance. Modifications in mRNA expression patterns following stenting deserve further study to better establish potential molecular targets to promote aneurysm healing.

An intimate interplay between precocious, migrating pericytes and endothelial cells governs human fetal brain angiogenesis

In order to better understand the process of angiogenesis in the developing human brain, we have examined the spatial relationship and relative contributions of endothelial cells and pericytes, the two primary cell types involved in vessel growth, together with their relation with the vascular basement membrane. Pericytes were immunolocalized through use of the specific markers nerve/glial antigen 2 (NG2) proteoglycan, endosialin (CD248) and the platelet-derived growth factor receptor beta (PDGFR-beta), while endothelial cells were identified by the pan-endothelial marker CD31 and the blood brain barrier (BBB)-specific markers claudin-5 and glucose transporter isoform 1 (GLUT-1). The quantitative analysis demonstrates that microvessels of the fetal human telencephalon are characterized by a continuous layer of activated/angiogenic NG2 pericytes, which tightly invest endothelial cells and participate in the earliest stages of vessel growth. Immunolabelling with anti-active matrix metalloproteinase-2 (aMMP-2) and anti-collagen type IV antibodies revealed that aMMP-2 producing endothelial cells and pericytes are both associated with the vascular basement membrane during vessel sprouting. Detailed localization of the two vascular cell types during angiogenesis suggests that growing microvessels of the human telencephalon are formed by a pericyte-driven angiogenic process in which the endothelial cells are preceded and guided by migrating pericytes during organization of the growing vessel wall.

Ganglioside GD1a negatively regulates matrix metalloproteinase-9 expression in mouse FBJ cell lines at the transcriptional level

Mouse FBJ virus-induced osteosarcoma FBJ-S1 cells rich in GD1a are not readily metastatic, whereas FBJ-LL cells with low levels of GD1a are highly metastatic. GD1a was previously shown to suppress metastasis of mouse FBJ cells and to upregulate caveolin-1 and stromal interaction molecule 1 expression. The present study demonstrates that matrix metalloproteinase-9 (MMP-9) expression renders FBJ-LL cells invasive. MMP-9 is inversely regulated by GD1a, based upon four observations: MMP-9 mRNA content was 5 times higher in FBJ-LL cells than FBJ-S1 cells; a GD1a-re-expressing FBJ-LL cell variant produced through beta1,4GalNAcT-1 cDNA transfection expressed lower levels of MMP-9; exogenous addition of GD1a to FBJ-LL cells decreased MMP-9 production in a dose- and time-dependent manner; and treatment of GD1a-rich cells with D-PDMP or siRNA targeting St3gal2 decreased GD1a expression, but augmented MMP-9 expression. This is the first report demonstrating that GD1a negatively regulates expression of MMP-9 at the transcriptional level.

Effect of a Dihydrobenzofuran Derivative on Lipid Hydroperoxide-Induced Rabbit Corneal Neovascularization

The aim of this study was to investigate the effect of A-3922, a dihydrobenzofuran derivative, on linoleic acid hydroperoxide (LHP)-induced corneal neovascularization (NV) in a rabbit model. Male New Zealand rabbits received intraperitoneal (i.p.) injections of 10 or 30 mg/kg per day A-3922 or its vehicle as control for 3 days. One day after i.p. injections, LHP was injected with a 30-gauge needle into the corneal stroma of the superior quadrant 4.5-mm below the limbus. Photographs of the vessels were taken for digital analysis with a surgical microscope. Vascular endothelial growth factor (VEGF) was measured using an immunoassay kit, and matrix metalloproteinase (MMP)-9 was measured by gelatin zymography in corneal samples. At 7 days post-LHP injection, the total vessel length was 26.7 +/- 3.8 mm in the control animals (n = 8), 16.1 +/- 0.8 mm in the A-3922 (10 mg/kg)-treated group (n = 5), and 11.4 +/- 2.1 mm in the 30 mg/kg group (n = 8, P<0.01 vs control), respectively. After LHP injection, the content of VEGF and MMP-9 activity were increased in the superior cornea, but these were not influenced by A-3922 treatments. These results indicate that LHP-induced corneal NV is inhibited by treatment with A-3922 and therefore may represent a potential pharmacological intervention for ocular neovascularization disorders.

Angiogenesis and antiangiogenic therapy in hematologic malignancies

Angiogenesis, the generation of new blood capillaries from preexisting blood vessels, is tightly regulated in the adult organism. Although many of the initial studies were performed on solid tumors, increasing evidence indicates that angiogenesis also plays an important role in hematologic malignancies. Overexpression of angiogenic factors in particular VEGF and bFGF in most hematologic malignancies may explain the increased angiogenesis found in these malignancies and correlate with poor prognosis as well as decreased overall survival. In this review, we focus on the current literature of angiogenesis and antiangiogenic therapy in hematologic malignancies, and finally describe advances and potential challenges in antiangiogenic treatment in hematologic malignancies.

Cancer as an evolutionary and ecological process

Neoplasms are microcosms of evolution. Within a neoplasm, a mosaic of mutant cells compete for space and resources, evade predation by the immune system and can even cooperate to disperse and colonize new organs. The evolution of neoplastic cells explains both why we get cancer and why it has been so difficult to cure. The tools of evolutionary biology and ecology are providing new insights into neoplastic progression and the clinical control of cancer.

Upregulated EMMPRIN/CD147 might contribute to growth and angiogenesis of gastric carcinoma: a good marker for local invasion and prognosis

Tumour growth depends on angiogenesis, which is closely associated with vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs). Extracellular MMP inducer (EMMPRIN) was reported to involve in the progression of malignancies by regulating expression of VEGF and MMPs in stromal cells. To clarify the role of EMMPRIN in progression and angiogenesis of gastric carcinoma, expression of EMMPRIN, ki-67, MMP-2, MMP-9 and VEGF was examined on tissue microarray containing gastric carcinomas (n=234) and non-cancerous mucosa adjacent to carcinoma (n=85) by immunohistochemistry. Additionally, microvessel density (MVD) was assessed after labelling with anti-CD34 antibody. Extracellular MMP inducer expression was compared with clinicopathological parameters of tumours, including levels of ki-67, MMP-2, MMP-9 and vascular endothelial growth factor (VEGF), MVD as well as survival time of carcinoma patients. Gastric carcinoma cell lines (HGC-27, MKN28 and MKN45) were studied for EMMPRIN expression by immunohistochemistry and Western blot. Extracellular MMP inducer expression was gradually increased from normal mucosa to carcinomas through hyperplastic or metaplastic mucosa of the stomach (P<0.05). There was strong EMMPRIN expression in all gastric carcinoma cell lines despite different levels of glycosylation. Extracellular MMP inducer expression was positively correlated with tumour size, depth of invasion, lymphatic invasion, expression of ki-67, MMP-2, MMP-9 and VEGF of tumours (P<0.05), but not with lymph node metastasis, UICC staging or differentiation (P>0.05). Interestingly, there was a significantly positive relationship between EMMPRIN expression and MVD in gastric carcinomas (P<0.05). Survival analysis indicated EMMPRIN expression to be negatively linked to favourable prognosis (P<0.05), but not be independent factor for prognosis (P>0.05). Further analysis showed three independent prognostic factors, depth of invasion, lymphatic and venous invasion, to influence the relationship between EMMPRIN expression and prognosis. Upregulated expression of EMMPRIN possibly contributes to genesis, growth and local invasion of gastric carcinomas. Altered EMMPRIN expression might enhance growth, invasion and angiogenesis of gastric carcinoma via upregulating MMP expression of both stromal fibroblasts and gastric cancer cells and could be considered as an objective and effective marker to predict invasion and prognosis.

Matrix Metalloproteinase-2 and -9 Expression Correlated with Angiogenesis in Human Adenomyosis

BACKGROUND

Adenomyosis is an important cause of dysmenorrhea and infertility for women all over the world, however, the pathogenesis has not been completely elucidated. The purpose of the study was to investigate the role of matrix metalloproteinases (MMPs) and their relation to angiogenesis in human adenomyosis.

METHODS

Adenomyotic endometrial specimens were removed by hysterectomy from 68 women with adenomyosis. The control group consisted of 26 normal endometrial specimens. Immunohistochemistry was used to demonstrate expression of MMP-2, -9, vascular endothelial growth factor (VEGF) and microvessel density (MVD). Staining intensity was analyzed by computerized image analysis system.

RESULTS

In both eutopic and ectopic endometrium of adenomyosis, the expression of MMP-2, -9 as well as VEGF was significantly greater than in normal endometrium (p < 0.05). MVD was higher in ectopic endometrium than eutopic endometrium with or without adenomyosis (p < 0.05). In adenomyosis, a positive correlation was observed between VEGF expression and MMP-2 (p < 0.001, r = 0.583) as well as MMP-9 expression (p = 0.002,r = 0.490). A positive correlation was also found between MVD and MMP-2 (p < 0.001,r = 0.589) or MMP-9 expression (p < 0.001,r = 0.589).

CONCLUSION

Our results indicate that the elevation of MMP-2, -9 expression may have an important role in the development of adenomyosis, probably through contributing to invasion of endometrial tissues into the myometrium and angiogenesis in adenomyotic implants.

Changes in immunolocalisation of beta-dystroglycan and specific degradative enzymes in the osteoarthritic synovium

OBJECTIVE

To investigate the immunolocalisation of beta-dystroglycan (beta-DG) and specific matrix metalloproteinases (MMPs)-3, -9, -13 and a disintegrin like and metalloproteinase thrombospondin type 1 motif 4 (ADAMTS-4) within the joint tissues of patients with osteoarthritis (OA) and unaffected controls.

DESIGN

Cartilage, synovium and synovial fluid were obtained from the hip joints of five osteoarthritic (patients undergoing total hip replacement) and five control hip joints (patients undergoing hemiarthroplasty for femoral neck fracture). The samples were analysed for beta-DG protein using Western blot technique and by immunohistochemistry for tissue distribution of beta-DG, MMP-3, -9, -13, and ADAMTS-4.

RESULTS

beta-DG was detected in the smooth muscle of both normal and osteoarthritic synovial blood vessels. Importantly, beta-DG was detected in endothelium of blood vessels of OA synovium, but not in the control endothelium. In the endothelium of osteoarthritic synovial blood vessels, beta-DG co-localised with MMP-3 and -9. MMP-13 and ADAMTS-4 showed no endothelial staining, and only weak staining of the vascular smooth muscle was found. In contrast, we did not detect beta-DG protein in cartilage or synovial fluid.

CONCLUSIONS

beta-DG has been shown to have a role in angiogenesis, and our results demonstrate for the first time that there are clear differences in beta-DG staining between OA and control synovial blood vessels. The specific immunolocalisation of beta-DG within endothelium of inflamed OA blood vessels and its co-localisation with MMP-3 and -9, reported to have pro-angiogenic roles and believed to be involved in beta-DG cleavage, may also suggest that beta-DG plays a role in angiogenesis accompanying OA.

Angiogenesis - understanding the mathematical challenge

Biological mathematics is based on the development of mathematical descriptions of biological systems and behaviour. We are interested in developing mathematical models of capillary sprouting, and have adopted a novel approach to our modelling, in that the mathematics is based on the biochemistry underpinning cell behaviour. By considering the crucial steps of the angiogenic process, and through an understanding of the biochemistry involved, we successfully developed a preliminary model of angiogenesis. More importantly, our approach is applicable to many other areas of biological research. As mathematics remains a mystery to the majority of life scientists, we have aimed to describe our mathematical modelling strategy in biological terms. The assumptions and simplifications that form the basis of the modelling are explained, pinpointing the manner in which the different biological processes are linked via the mathematics. Examples of simulations using the mathematical model are shown, highlighting the success of our approach.

Apparent suppression of MMP-9 activity by GD1a as determined by gelatin zymography

Gelatin zymography is widely used to detect and evaluate matrix metalloproteinase-9 (MMP-9) activity. MMP-9 transcription was previously shown to be negatively regulated by ganglioside GD1a [D. Hu, Z. Man, T. Xuan, P. Wang, T. Takaku, S. Hyuga, X.S. Yao, T. Sato, S. Yamagata, T. Yamagata, Ganglioside GD1a regulation of matrix metalloproteinase-9 (MMP-9) expression in mouse FBJ cell Lines: GD1a suppression of MMP-9 expression stimulated by PI3K-Akt and p38 though not by the Erk signaling pathway, 2006, submitted for publication.]. Zymography of MMP-9 of FBJ-M5 cells preincubated with GD1a indicated a greater decrease in activity than expected from mRNA suppression. Incubation of conditioned medium containing MMP-9 with GD1a caused MMP-9 activity to decrease. Examination was thus made to confirm that MMP-9 activity is actually suppressed and/or MMP-9 protein undergoes degradation by GD1a. GD1a was found to have no effect on MMP-9 activity and Western blots indicated GD1a not to diminish MMP-9 during electrophoresis under reducing conditions. GD1a appeared to mediate the binding of a portion of MMP-9 with certain molecules, with consequently greater molecular mass on the gel, to cause decrease in the activity of MMP-9 at the site where it would normally appear. Caution should be used in doing gelatin zymography since molecules other than GD1a may similarly work, causing decrease in MMP-9 activity in zymography.

Statins, nitric oxide and neovascularization

Several landmark clinical trials suggest that 3-hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors (statins) have additional cardiovascular protective activity that may function independently of their ability to lower serum cholesterol. The cardiovascular protective effects of statins are partly caused by the activation of postnatal neovascularization. At therapeutic doses, statins promote proliferation, migration and survival of endothelial cells, induce mobilization and differentiation of bone marrow-derived endothelial progenitor cells by stimulating the serine/threonine protein kinase Akt (also known as protein kinase B) and nitric oxide (NO) signal pathway. However, at excessive doses, statins may decrease protein isoprenylation as well as inhibit endothelial cell growth and migration. NO is an important signaling molecule that regulates a wide range of physiological and pathological processes in different tissues. There is substantial evidence that effective neovascularization requires endothelium-derived NO. Statins have pleiotropic effects on the expression and activity of endothelial nitric oxide synthase (eNOS) and lead to improved NO bioavailability. NO plays an important role in the effects of statins on neovascularization. In this review, we focus on the effects of statins on neovascularization and highlight specific novel targets, such as endothelial progenitor cells and NO.

Microarray interrogation of human metanephric mesenchymal cells highlights potentially important molecules in vivo

Many molecules have been implicated in kidney development, often based on experimental animal studies with organ cultures and cell lines. There are very few studies, however, that have directly addressed equivalent living human embryonic tissues. We generated renal mesenchymal cell lines from normal human metanephroi and used a microarray strategy to define changes in gene expression after stimulation with growth factors which enhance nephrogenesis in rodents. Changes were observed in 1) genes modulating diverse general cellular processes, such as matrix metalloproteinase 1 and stanniocalcin 1; 2) genes previously implicated in organogenesis e.g., sprouty 4 and midline 1; and 3) genes involved in blood vessel growth, including angiopoietin 1 and 4. Expression of these same genes was subsequently confirmed in vivo. Our novel data have identified several previously unhighlighted genes that may be implicated in differentiation programs within early human nephrogenesis.

Histone deacetylase 7 maintains vascular integrity by repressing matrix metalloproteinase 10

Development and homeostasis of the cardiovascular system require intimate interactions between endothelial and smooth muscle cells, which form a seamless circulatory network. We show that histone deacetylase 7 (HDAC7) is specifically expressed in the vascular endothelium during early embryogenesis, where it maintains vascular integrity by repressing the expression of matrix metalloproteinase (MMP) 10, a secreted endoproteinase that degrades the extracellular matrix. Disruption of the HDAC7 gene in mice results in embryonic lethality due to a failure in endothelial cell-cell adhesion and consequent dilatation and rupture of blood vessels. HDAC7 represses MMP10 gene transcription by associating with myocyte enhancer factor-2 (MEF2), a direct activator of MMP10 transcription and essential regulator of blood vessel development. These findings reveal an unexpected and specific role for HDAC7 in the maintenance of vascular integrity and have important implications for understanding the processes of angiogenesis and vascular remodeling during cardiovascular development and disease.

Abdominal Aortic Aneurysm Rupture Is Associated With Increased Medial Neovascularization and Overexpression of Proangiogenic Cytokines

Objective— Matrix metalloproteinase (MMP) activity has been linked to abdominal aortic aneurysm (AAA) rupture. Medial neovascularization (MNV), a histopathologic characteristic of AAAs, involves proteolytic degradation of extracellular matrix by MMPs to facilitate endothelial cell migration. The role of MNV in aneurysm rupture is unknown. This study investigated whether MNV is increased in aneurysm rupture.

Methods and Results— Biopsy samples from aneurysm rupture edge were compared with control biopsy samples from aneurysm wall at the level of rupture and from anterior sac in 12 ruptured AAAs. Further controls were obtained from anterior sac of 10 nonruptured AAAs. MNV, microvessel diameter, maturity index, and inflammatory infiltrate were quantified using morphometric analyses following immunohistochemistry. Expression of proangiogenic mediators was quantified using quantitative real-time-polymerase chain reaction. Compared with anterior sac and aneurysm wall at level of rupture, MNV was increased ( P <0.001) in rupture edge biopsy samples and consisted of smaller diameter ( P <0.001) and more immature microvessels ( P <0.001). mRNA expression of α v -integrin, vascular endothelial growth factor, vascular endothelial-cadherin, monocyte chemoattractant protein-1, and vimentin was increased ( P <0.05) in rupture edge biopsy samples.

Conclusions— This study demonstrated increased medial neovascularization and overexpression of proangiogenic cytokines at aneurysm rupture edge. Further investigations into whether this angiogenic response was a causative factor of aneurysm rupture are needed.

Melanoma cell-derived vascular endothelial growth factor induces endothelial tubulogenesis within fibrin gels by a metalloproteinase-mediated mechanism

Angiogenesis is a process required not only for embryonal development but is encountered in wound healing and in pathological situations such as tumour growth. In vitro, formation of capillary-like structures can be induced by seeding human microvascular endothelial cells (HDMECs) on top of a fibrin matrix in the presence of phorbol 12-myristate 13-acetate (PMA) as a stimulating agent. In this study, we show that supernatants collected from high-invasive melanoma cells (BLM) induce the formation of tubular structures similar to PMA treatment whereas supernatants from low-invasive cells (WM164) did not. Analysis of proteins secreted into the supernatant of both melanoma cell lines identified differential expression of several pro-angiogenic proteins in high- and low-invasive melanoma cells. Vascular endothelial growth factor (VEGF) was strongly expressed by high- but not by low-invasive melanoma cells. Neutralisation of VEGF as well as inhibition of matrix metalloproteases (MMPs) using the broad spectrum MMP inhibitor 1,10-phenanthroline, both strongly reduced the melanoma-induced tube formation. PMA treatment of HDMECs on a fibrin matrix stimulated MT1-MMP synthesis, indicating that this protease is involved in PMA-induced angiogenesis. In addition, stimulation of HDMECs by supernatants of BLM melanoma cells resulted in a strong induction of ADAM-15, which is known to act as a metalloproteinase. In conclusion, these results show that VEGF released by melanoma cells is an important mediator of neo-vascularisation and that this process depends on the presence of metalloproteinases.

Expression of Ets-1 in human clear cell renal cell carcinomas: implications for angiogenesis

Expression of vascular endothelial growth factor (VEGF) has been reported in renal cell carcinoma (RCC), a highly angiogenic carcinoma. However, little or no information is available on the expression of Ets-1, which is one of the target molecules of VEGF. In the present study, we examined the expression of Ets-1 and VEGF in RCC by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR), and correlations between expression and the microvessel density (MVD) were evaluated. Ets-1 was immunolocalized to carcinoma cells and endothelial cells of the microvessels in clear cell RCC, but not in papillary RCC. Immunohistochemical Ets-1 expression and MVD were significantly higher in clear cell RCC than in papillary RCC. Predominant mRNA expression of Ets-1 in clear cell RCC was confirmed by RT-PCR. The expression of Ets-1 correlated directly with MVD in clear cell RCC. Hypoxic treatment upregulated the mRNA expression of Ets-1 and VEGF in cell lines derived from clear cell RCC, suggesting that hypoxia is a key regulator for these molecules. These results demonstrate the expression of Ets-1 in human clear cell RCC and suggest the possibility that Ets-1 is involved in angiogenesis in clear cell RCC.

Molecular balance of capillary tube formation versus regression in wound repair: role of matrix metalloproteinases and their inhibitors

In this review, we discuss the identification of distinct matrix metalloproteinases (MMPs) and their inhibitors that differentially control the processes of capillary tube formation (morphogenesis) versus capillary tube regression in three-dimensional (3D) collagen matrices. This work directly relates to both granulation tissue formation and regression during wound repair. The membrane metalloproteinase, MT1-MMP (MMP-14), is required for endothelial cell (EC) tube formation using in vitro assays that mimic vasculogenesis or angiogenic sprouting in 3D collagen matrices. These events are markedly blocked by small interfering RNA (siRNA) suppression of MT1-MMP in ECs or by addition of tissue inhibitor of metalloproteinases (TIMPs)-2,-3, and -4 but not TIMP-1. In contrast, MMP-1 and MMP-10 are strongly induced during EC tube formation to regulate the process of tube regression (following activation by serine proteases) rather than formation. TIMP-1, which selectively inhibits soluble MMPs, blocks tube regression by inhibiting MMP-1 and MMP-10 while having no influence on EC tube formation. siRNA suppression of MMP-1 and MMP-10 markedly blocks tube regression without affecting tube formation. Furthermore, we discuss that pericyte-induced stabilization of EC tube networks in our model system appears to occur through EC-derived TIMP-2 and pericyte-derived TIMP-3 to block both the capillary tube formation and regression pathways.

Angiogenesis in colorectal cancer: prognostic and therapeutic implications

Angiogenesis is important for tumor growth and metastasis. This account reviews the clinicopathological studies conducted in the field of angiogenesis in colorectal cancer, the methods of assessing vascular-related characteristics in tissue sections and provides a background for the usefulness of antiangiogenic policies along with chemotherapy and radiotherapy. Highly angiogenic colorectal tumors are associated with aggressive histopathological features and poor patients' survival. Similarly, factors stimulating angiogenesis, such as vascular endothelial growth factor (VEGF), thymidine phosphorylase (TP), and others, are commonly related to increased vascular density (VD) and, therefore, to an unfavorable clinical course. Anti-VEGF agents have improved prognosis in patients with metastatic colorectal cancer, when added to standard chemotherapy. It is expected that, in addition to adjuvant chemotherapy and radiotherapy, agents blocking the stimulatory effect of VEGF on endothelial cells would prove beneficial to the patient.

Photodynamic therapy down-regulates the invasion promoting factors in human oral cancer

Squamous cell carcinomas of the head and neck are characterized by their high tendency for invasion and metastasis. Several studies have identified the roles of matrix metalloproteinases (MMPs), vascular endothelial growth factors (VEGF) and urokinase plasminogen activators (uPA) in this process. Photodynamic Therapy (PDT) is an emerging treatment currently in clinical practice for the treatment of early cancer. Here we evaluate, in vitro, the influence of PDT on the expression of these molecules. A series of human keratinocyte cell lines derived from human oral squamous cell carcinomas (OSCC) were used as the PDT 'targets' in this study. Each cell line was subjected to sublethal dose of PDT. Activity of MMP-2, MMP-9, MMP-13, uPA and VEGF were evaluated at protein levels using zymography and ELISA on culture medium. For uPA, a chromogenic assay was performed. Gelatin zymography results revealed that, in control medium, MMP-9 and MMP-2 were secreted in proform. MMP-2 was highly expressed by H376 cells while VB6 and UP cells relatively show similar MMP-2 with comparatively low expression. For MMP-9, the latent type was highly expressed by VB6 cells and only slightly by H376, while active-MMP-9 was expressed by VB6 cell line only. Following PDT, both active and latent MMP-2 and MMP-9 were down regulated by UP and VB6 cells (p<0.001), while H376 showed an increase in active-MMP-2. These observations were supported by ELISA. This study has demonstrated that, PDT causes the suppression of factors responsible for tumour invasion which may be of therapeutic value.

Regulation of serine protease inhibitor-E2 and plasminogen activator expression and secretion by follicle stimulating hormone and growth factors in non-luteinizing bovine granulosa cells in vitro

During ovarian follicle growth, there is expansion of the basal lamina and changes in the follicular extracellular matrix (ECM) that are mediated in part by proteolytic enzyme cascades regulated by tissue-type plasminogen activator (tPA) and urokinase plasminogen activator (uPA). One PA inhibitor, serine protease inhibitor-E2 (SERPINE2) is expressed in granulosa but not theca cells, and expression changes with follicle development. In this study, we hypothesized that PA and SERPINE2 expression/secretion by granulosa cells are regulated by FSH and growth factors. SERPINE2 mRNA and protein levels, tPA gene expression and uPA secretion were stimulated by FSH. Insulin-like growth factor-I stimulated SERPINE2 secretion and uPA activity, and decreased secreted tPA activity and gene expression. Bone morphogenetic protein-7 increased SERPINE2 secretion and expression and tPA secretion. In contrast, fibroblast growth factor-2 inhibited tPA secretion and SERPINE2 secretion and expression. Epidermal growth factor inhibited SERPINE2 secretion and expression, but increased secreted tPA activity. Estradiol and SERPINE2 secretion were highly positively correlated, but estradiol did not alter SERPINE2 expression. These data demonstrate that SERPINE2 expression and protein secretion are regulated by FSH and growth factors in non-luteinizing bovine granulosa cells. As estradiol is a known marker of follicle health, and SERPINE2 is an anti-apoptotic factor, we propose that SERPINE2 is involved in the regulation of atresia in bovine follicles.

Matrix metalloproteinases and tumor metastasis

Functions of individual matrix metalloproteinases (MMPs) differentially expressed by tumor cells and stromal cells, are finely regulated by their spatial as well as temporal interactions with distinct cellular and extracellular components of the tumor microenvironment and also distant pre-metastatic sites. Certain aspects of MMP involvement in tumor metastasis such as tumor-induced angiogenesis, tumor invasion, and establishment of metastatic foci at the secondary site, have received extensive attention that resulted in an overwhelming amount of experimental and observational data in favor of critical roles of MMPs in these processes. In particular, dependency of tumor angiogenesis on the activity of MMPs, especially that of MMP-9, renders this step possibly the most effective target of synthetic MMP inhibitors. MMP functioning in other stages of metastasis, including the escape of individual tumor cells from the primary tumor, their intravasation, survival in circulation, and extravasation at the secondary site, have not yet received enough consideration, resulting in insufficient or controversial data. The major pieces of evidence that are most compelling and clearly determine the role and involvement of MMPs in the metastatic cascade are provided by molecular genetic studies employing knock-out or transgenic animals and tumor cell lines, modified to overexpress or downregulate a specific MMP. Findings from all of these studies implicate different functional mechanisms for both tumor and stromal MMPs during distinct steps of the metastatic cascade and indicate that MMPs can exhibit pro-metastatic as well as anti-metastatic roles depending on their nature and the experimental setting. This dual function of individual MMPs in metastasis has become a major focus of this review.

MMP-9 in B-cell chronic lymphocytic leukemia is up-regulated by alpha4beta1 integrin or CXCR4 engagement via distinct signaling pathways, localizes to podosomes, and is involved in cell invasion and migration

B-cell chronic lymphocytic leukemia (B-CLL) progression is determined by malignant cell extravasation and lymphoid tissue infiltration. We have studied the role and regulation of matrix metalloproteinase-9 (MMP-9) in B-CLL cell migration and invasion. Adhesion of B-CLL cells to the fibronectin fragment FN-H89, VCAM-1, or TNF-alpha-activated human umbilical vein endothelial cells (HUVECs) up-regulated MMP-9 production, measured by gelatin zymography. This effect was mediated by alpha4beta1 integrin and required PI3-K/Akt signaling. The chemokine CXCL12 also up-regulated MMP-9, independently of alpha4beta1 and involving ERK1/2 but not Akt activity. Accordingly, alpha4beta1 engagement activated the PI3-K/Akt/NF-kappaB pathway, while CXCL12/CXCR4 interaction activated ERK1/2/c-Fos signaling. Anti-MMP-9 antibodies, the MMP-9 inhibitor TIMP-1, or transfection with 3 different MMP-9 siRNAs significantly blocked migration through Matrigel or HUVECs. Cell-associated MMP-9 was mainly at the membrane and contained the proactive and mature forms. Moreover, B-CLL cells formed podosomes upon adhesion to FN-H89, VCAM-1, or fibronectin; MMP-9 localized to podosomes in a PI3-K-dependent manner and degraded a fibronectin/gelatin matrix. Our results are the first to show that MMP-9 is physiologically regulated by alpha4beta1 integrin and CXCL12 and plays a key role in cell invasion and transendothelial migration, thus contributing to B-CLL progression. MMP-9 could therefore constitute a target for treatment of this malignancy.

Endocannabinoids and reactive nitrogen and oxygen species in neuropathologies

Neuropathologies that affect our population include ischemic stroke and neurodegenerative diseases of immune origin, including multiple sclerosis. The endocannabinoid system in the brain, including agonists anandamide (arachidonyl ethanolamide) and 2-arachidonoylglycerol, and the CB1 and CB2 cannabinoid receptors, has been implicated in the pathophysiology of these disease states, and can be a target for therapeutic interventions. This review concentrates on cellular signal transduction pathways believed to be involved in the cellular damage.

Increased plasma concentration of matrix metalloproteinase-7 in patients with coronary artery disease

BACKGROUND

Plaque rupture is often associated with breakdown of the extracellular matrix in the shoulder region of a plaque. We tested whether plasma concentrations of various matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-1 (TIMP-1) could serve as markers for plaque instability as well as relationships between plasma MMPs and inflammatory markers.

METHODS

The study group included 65 men with angiographically verified CAD (45 with stable and 20 with unstable CAD) and 28 healthy controls. Circulating MMP, TIMP-1, C-reactive protein, and cytokine concentrations were measured by ELISA. Leukocyte subtype counts in whole blood were determined, and T-cell subsets and natural killer cells were measured by flow cytometry. Differences in continuous variables between groups were tested by ANOVA with the Scheffé F-test used as a post hoc test, and correlations were analyzed by a linear regression method.

RESULTS

The plasma concentration of MMP-7 was increased in patients with stable and unstable CAD, whereas MMP-2 and -3 concentrations were decreased. The plasma concentration of TIMP-1 was significantly increased in patients with unstable CAD. MMP-2, -3, and -7 showed no correlations with established markers of inflammation. However, MMP-2 correlated positively with the number of natural killer cells in patients with stable and unstable CAD.

CONCLUSION

Plasma concentrations of MMPs and TIMPs may be markers of CAD but appear to be differentially regulated.

Expression of kallikrein, bradykinin b2 receptor, and endothelial nitric oxide synthase in placenta in normal gestation, preeclampsia, and placenta accreta

In an effort to define the varied expression of three vasoactive markers in the clinical models of normal placenta/ normal invasion (n = 11), preeclampsia/restricted trophoblast invasion (n = 15), and placenta accreta/exaggerated invasion (n = 6), we performed semiquantitative immunohistochemistry for kallikrein, bradykinin B2 receptor, and endothelial nitric oxide synthase (eNOS). In the floating villi, the syncytiotrophoblast expressed more kallikrein in placenta accreta (p < 0.05), than in normal and preeclamptic placentas, while the bradykinin B2 receptor and eNOS were similarly expressed in all groups; in the fetal endothelium, the bradykinin B2 receptor was enhanced in placenta accreta (p < 0.005), but kallikrein and eNOS were similarly expressed in the other two groups. In the extravillous trophoblast, both kallikrein and eNOS expression were higher in placenta accreta (p < 0.001), while the bradykinin B2 receptor signal was only enhanced in preeclampsia (p < 0.05). The presence and localization of kallikrein, the bradykinin B2 receptor, and eNOS in the fetomaternal interface in the three study conditions supports a local role for interrelated vasodilatory/antiaggregating systems. This first report of the variations observed in kallikrein and eNOS in a condition of exaggerated trophoblast invasion supports the participation of vasodilatation in trophoblast migration.

Functional role of matrix metalloproteinase-28 in the oral squamous cell carcinoma

The newly identified MMP-28 has been shown to be expressed in several types of carcinomas, however, its functional role in transformation events is unknown. This study was to assess whether this proteinase plays a role in oral tumor malignancy. By using RT-PCR, we found that expression of MMP-28 was significantly higher in 92 oral squamous cell carcinomas (OSCCs) (52/92, 56.5%) than in seven oral premalignant lesions (OPMLs) (0/7, 0%) (P=0.004). No statistically significant correlation was found between MMP-28 expression and tumor stage, thickness, size, and metastasis. Both mRNA and protein of MMP-28 were preferentially concentrated in OSCC specimens than in neighboring tissues as analyzed by semi-quantitative RT-PCR (P=0.015) and immunohistochemistry, respectively. Transfection of OSCC and esophageal carcinoma cell lines with MMP-28 antisense oligodeoxynucleotide (AODN) resulted in the reduced secretion of MMP-28 protein and the ability of colony formation in soft agar without affecting cell growth. Our findings show the close correlation between MMP-28 and OSCC, and support a role for MMP-28 in the anchorage-independent growth of both OSCC and esophageal carcinomas.

Prognostic Role of Protease-Activated Receptors 1 and 4 in Resected Stage IB Non-Small-Cell Lung Cancer

BACKGROUND

Protease-activated receptor (PAR)-1 and PAR-4 are involved in extracellular matrix invasion and angiogenesis.

PATIENTS AND METHODS

A series of 60 resected stage IB non-small-cell lung cancers (NSCLCs), including 30 adenocarcinomas (ADCs) and 30 squamous cell carcinomas (SCCs), were processed by immunohistochemistry with antibodies to PAR-1, PAR-4, vascular endothelial growth factor (VEGF), and CD34.

RESULTS

Protease-activated receptor-1 was expressed in 37 cases (62%) and PAR-4 in 39 (65%). Adenocarcinomas were significantly more positive than SCC for PAR-1 (17 vs. 8 cases) and PAR-4 (10 vs. 5 cases). Vascular endothelial growth factor was expressed in 42 cases (70%): 22 ADC and 20 SCC. A significant correlation emerged between PAR-1 and/or PAR-4 expression and VEGF but not with microvessel density. Median follow-up was 38 months; actuarial 5-year survival was 43%. At univariate analysis, 3-year survival was shorter in patients expressing PAR-4 versus negative cases (29% vs. 60%; P = 0.002). In 46 patients expressing PAR-1 and/or PAR-4, 3-year survival was 30% versus 68% in 14 patients with no PAR expression (P = 0.002). A trend toward shorter 3-year survival was seen in PAR-1-positive versus PAR-1-negative cases (34% vs. 46%; P = 0.06). Multivariate analysis identified expression of PAR-1 and/or PAR-4 as an independent prognostic factor for reduced survival in resected stage IB NSCLC.

CONCLUSION

Expression of PAR-1 and PAR-4 in early-stage NSCLC could be included in a molecular algorithm for the selection of patients eligible for adjuvant studies.

Benzoquinone ansamycin heat shock protein 90 inhibitors modulate multiple functions required for tumor angiogenesis

Heat shock protein 90 (Hsp90) is a molecular chaperone involved in maintaining the correct conformation and stability of its client proteins. This study investigated the effects of Hsp90 inhibitors on client protein expression and key cellular functions required for tumor angiogenesis. The benzoquinone ansamycin Hsp90 inhibitors geldanamycin and/or its derivatives 17-allylamino-17-demethoxygeldanamycin (17-AAG) and 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin inhibited production of vascular endothelial growth factor (VEGF)-A by tumor cells and blocked proliferative responses of human endothelial cells at nanomolar concentrations. 17-AAG also significantly reduced endothelial cell migration, tubular differentiation, invasion through Matrigel, and secretion of urokinase-type plasminogen activator at concentrations at or below those that inhibited proliferation. 17-AAG significantly reduced expression of VEGF receptor (VEGFR)-2 and established Hsp90 client proteins in human endothelial cells in vitro as well as in mouse vena cava, mesenteric vessels, and blood vessels within human tumor xenografts in vivo; this was associated with decreased tumor microvessel density. Finally, we showed for the first time that Hsp90 inhibitors also reduce expression of VEGFR-1 on human vascular endothelial cells, VEGFR-3 on lymphatic endothelial cells in vitro, and all three VEGFRs on mouse vasculature in vivo. Thus, we identify Hsp90 inhibitors as important regulators of many aspects of tumor angiogenesis (and potentially lymphangiogenesis) and suggest that they may provide therapeutic benefit not only via direct effects on tumor cells but also indirectly by inhibiting the production of angiogenic cytokines and responses of activated endothelial cells that contribute to tumor progression and metastasis.

Mechanisms of Disease: angiogenesis in urologic malignancies

Angiogenesis is critical for growth of tumors and their metastasis. In this article we review the literature on studies of angiogenesis pathways and markers for renal cancer, prostate cancer and bladder cancer. Overall, there is clear evidence that markers of angiogenesis and expression of angiogenic factors are associated with adverse outcomes in each of these tumor types. Relatively few angiogenic pathways have been investigated so far, although over 50 factors are known to be involved, and little has been studied on the antiangiogenic pathways and their suppression. The failing in many of the studies is small size and lack of suitable statistical analysis. Nevertheless, this review demonstrates the importance of these pathways and the need to develop selection criteria for patients who are candidates for antiangiogenic therapies. On the basis of the expression profiles reported so far, therapies that target vascular endothelial growth factor should be considered for the treatment of renal, prostate and bladder cancers. As most tumors express factors that are involved in multiple angiogenic pathways, further research is needed to determine which are coregulated and what the most common patterns are.

Relationships between the level of matrix metalloproteinase-2 and tumor size of breast cancer

BACKGROUND

The involvements of matrix metalloproteinase-2 (MMP-2) in the pathogenesis of breast cancers have been established. We determined the concentrations of MMP-2 in serum samples and tumor tissues of breast cancer patients.

METHODS

Gelatin zymography and ELISA were used to measure MMP-2 and MMP-9 concentrations in 90 breast cancer patients, including 60 tissue samples and 30 serum samples.

RESULTS

ProMMP-2, activated MMP-2, proMMP-9 and activated MMP-9 levels were significantly higher in tumor tissues than that of corresponding paired adjacent normal tissue of 60 breast cancer patients (p<0.01). Further linear regression analysis has showed that the tumor size positively correlated with MMP-2 level in tumor tissue samples (R=0.55, p<0.0001), as well as with that of in serum samples (R=0.398, p=0.032). In addition, further statistical analysis for clinic pathological parameters revealed that MMP-2 level was significantly increased in patients with metastasis (p<0.05). Furthermore, MMP-2 level was significantly different between tumor grades (p=0.006).

CONCLUSIONS

MMP-2 levels in serum and tumor tissue might reflect the severity of invasion of breast cancer and various MMP inhibitors might be selectively used as potential anti-metastasis agents according to tumor size.

Corneal angiogenic privilege: angiogenic and antiangiogenic factors in corneal avascularity, vasculogenesis, and wound healing (an American Ophthalmological Society thesis)

PURPOSE

To determine the molecular basis of corneal avascularity during wound healing and determine the role of angiogenic and antiangiogenic factors in corneal vasculogenesis.

METHODS

The expression of proangiogenic factors (vascular endothelial growth factor [VEGF]; basic fibroblast growth factor [bFGF]; matrix metalloproteinase-2 [MMP-2]; and membrane-type 1-MMP [MT1-MMP]) and antiangiogenic factors (pigment epithelium-derived factor [PEDF]; angiostatin; restin; and endostatin) was analyzed in avascular corneas and in models of corneal neovascularization (bFGF pellet implantation, intrastromal injection of MT1-MMP cDNA, and surgically induced partial limbal deficiency).

RESULTS

Immunohistochemistry demonstrated the presence of antiangiogenic factors (PEDF, angiostatin, restin, and endostatin) and proangiogenic molecules (VEGF, bFGF, MMP-2, and MT1-MMP) in the cornea after wounding. Proangiogenic MMPs were upregulated in stromal fibroblasts in the vicinity of invading vessels following bFGF pellet implantation. Corneal neovascularization (NV) was also induced by intrastromal injection of MT1-MMP naked cDNA in conjunction with de-epithelialization. Partial limbal deficiency (HLD-) resulted in corneal NV in MMP-7 and MMP-3 knockout mice but not in wild type controls.

CONCLUSIONS

Corneal angiogenic privilege is an active process involving the production of antiangiogenic factors to counterbalance the proangiogenic factors (which are upregulated after wound healing even in the absence of new vessels). Our finding that the potent antiangiogenic factors, angiostatin and endostatin, are colocalized with several MMPs during wound healing suggests that MMPs may be involved in the elaboration of these antiangiogenic molecules by proteolytic processing of substrates within the cornea.

Targeting integrins for the control of tumour angiogenesis

The crucial role of cell extracellular matrix communication in angiogenesis is well established; thus, it is not surprising that integrins have gained considerable attention as targets for the treatment of neovascular disease. Given the diversity of ligands and complexity of integrin signalling, a new appreciation for the divergent roles of integrins in angiogenesis is emerging. It is becoming clear that integrins regulate angiogenesis in both a positive and negative manner. New studies have provided a better understanding of integrin structure as it relates to ligand binding and signalling. This new insight has opened exciting possibilities for the design of novel inhibitors for clinical applications. In this review, studies concerning the cooperative interactions between integrins and regulatory molecules and possible new strategies for controlling angiogenesis will be discussed.

The role of circulating precursors in vascular repair and lesion formation

The accumulation of smooth muscle cells (SMCs) plays a principal role in atherogenesis, post-angioplasty restenosis and transplantation-associated vasculopathy. Therefore, much effort has been expended in targeting the migration and proliferation of medial smooth muscle cells to prevent occlusive vascular remodeling. Recent evidence suggests that bone marrow-derived circulating precursors can also give rise to endothelial cells and smooth muscle cells that contribute to vascular repair, remodeling, and lesion formation under physiological and pathological conditions. This article overviews recent findings on circulating vascular progenitor cells and describes potential therapeutic strategies that target these cells to treat occlusive vascular diseases.