Tissue inhibitors of metalloproteinase 2 inhibits endothelial cell migration through increased expression of RECK

Extracellular matrix proteins and tumor angiogenesis

Tumor development is a complex process that relies on interaction and communication between a number of cellular compartments. Much of the mass of a solid tumor is comprised of the stroma which is richly invested with extracellular matrix. Within this matrix are a host of matricellular proteins that regulate the expression and function of a myriad of proteins that regulate tumorigenic processes. One of the processes that is vital to tumor growth and progression is angiogenesis, or the formation of new blood vessels from preexisting vasculature. Within the extracellular matrix are structural proteins, a host of proteases, and resident pro- and antiangiogenic factors that control tumor angiogenesis in a tightly regulated fashion. This paper discusses the role that the extracellular matrix and ECM proteins play in the regulation of tumor angiogenesis.

Albumin expression is required for adipocyte differentiation of 3T3-L1 cells

We have previously demonstrated that albumin is directly involved in the formation of cytoplasmic lipid droplets in pancreatic stellate cells and may act as a downstream effector of adipogenic transcription factors, PPAR-gamma and C/EBP-alpha. Here, we investigated the role of albumin in adipocyte differentiation using 3T3-L1 cells. Albumin expression was significantly increased at later stages of adipocyte differentiation, which was accompanied with increased C/EBP-beta binding to albumin promoter. Suppression of albumin expression using short-hairpin RNA (shRNA) during differentiation led to a considerable reduction in lipid droplet formation, whereas albumin overexpression was stimulatory. Furthermore, point mutation in its fatty acid-binding sites inhibited lipid droplet formation. Consistent with these in vitro finding, Nagase analbuminemic rats displayed reduced fat accumulation. Therefore, our findings suggest that albumin may play a distinct role in adipocyte differentiation by promoting lipid accumulation.

Overexpression of miR-21 promotes an in vitro metastatic phenotype by targeting the tumor suppressor RHOB

Metastasis is a multistep process that involves the deregulation of oncogenes and tumor suppressors beyond changes required for primary tumor formation. RHOB is known to have tumor suppressor activity, and its knockdown is associated with more aggressive tumors as well as changes in cell shape, migration, and adhesion. This study shows that oncogenic microRNA, miR-21, represses RHOB expression by directly targeting the 3' untranslated region. Loss of miR-21 is associated with an elevation of RHOB in hepatocellular carcinoma cell lines Huh-7 and HepG2 and in the metastatic breast cancer cell line MDA-MB-231. Using in vitro models of distinct stages of metastasis, we showed that loss of miR-21 also causes a reduction in migration, invasion, and cell elongation. The reduction in migration and cell elongation can be mimicked by overexpression of RHOB. Furthermore, changes in miR-21 expression lead to alterations in matrix metalloproteinase-9 activity. Therefore, we conclude that miR-21 promotes multiple components of the metastatic phenotype in vitro by regulating several important tumor suppressors, including RHOB.

RECK is up-regulated and involved in chondrocyte cloning in human osteoarthritic cartilage

Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) is a membrane-anchored matrix metalloproteinase regulator, but its functions in cartilage are not fully understood. The aim of the present study was to examine the expression and functions of RECK in human osteoarthritic (OA) cartilage. Quantitative RT-PCR indicated that the expression level of RECK is significantly higher in OA cartilage than in normal cartilage. By immunohistochemical analysis, RECK was localized to chondrocytes in OA cartilage, and the immunoreactivity directly correlated with the Mankin score and degree of chondrocyte cloning and proliferation. In cultured OA chondrocytes, RECK was expressed on the cell surface by glycosylphosphatidylinositol anchoring. The expression was stimulated by insulin-like growth factor-1 and suppressed by interleukin-1 and tumor necrosis factor-alpha. Down-regulation of RECK by small interfering RNA showed reduced spreading and smaller focal adhesions in the chondrocytes. Chondrocyte migration in a monolayer wounding assay was increased by down-regulation of RECK and inhibited by RECK overexpression in an matrix metalloproteinase activity-dependent manner. On the other hand, chondrocyte proliferation was suppressed by RECK silencing, and this was associated with reduced phosphorylation of focal adhesion kinase and extracellular signal-regulated kinase, whereas the proliferation was enhanced by RECK overexpression. These data are the first to demonstrate that RECK is up-regulated in human OA cartilage and suggest that RECK plays a role in chondrocyte cloning probably through suppression and promotion of chondrocyte migration and proliferation, respectively.

TIMP-2 modulates VEGFR-2 phosphorylation and enhances phosphodiesterase activity in endothelial cells

In this study, we examine the effects of tissue inhibitor of metalloproteinases-2 (TIMP-2) on the phosphorylation status of specific phosphotyrosine residues on the vascular endothelial cell growth factor receptor-2 (VEGFR-2) cytoplasmic tail and examine the effects on associated downstream signaling pathways. To focus on metalloproteinase-independent mechanisms, we used the TIMP-2 analog known as Ala+TIMP-2 that is deficient in matrix metalloproteinase-inhibitory activity. Our experiments are designed to compare the effects of VEGF-A stimulation with or without Ala+TIMP-2 pretreatment, as well as basal responses in human microvascular endothelial cells. Our results show that Ala+TIMP-2 selectively alters the phosphorylation pattern of VEGFR-2 after VEGF-A stimulation and disrupts the downstream activation of PLC-gamma, Ca(+2) flux, Akt, and eNOS, as well as decreasing cGMP levels. Moreover, we observed an Ala+TIMP-2-induced reduction in cGMP levels typically elevated by exogenous NO donors implicating Ala+TIMP-2 in the direct activation of an isobutylmethylxanthine (IBMX)-sensitive cGMP phosphodiesterase activity. TIMP-2 suppression of endothelial mitogenesis and angiogenesis involves at least two mechanisms, one mediated by protein tyrosine phosphatase inhibition of VEGFR-2 activation as well as downstream signaling and a second mechanism involving direct activation of an IBMX-sensitive phosphodiesterase activity.

The tissue inhibitors of metalloproteinases (TIMPs): an ancient family with structural and functional diversity

Tissue inhibitors of metalloproteinases (TIMPs) are widely distributed in the animal kingdom and the human genome contains four paralogous genes encoding TIMPs 1 to 4. TIMPs were originally characterized as inhibitors of matrix metalloproteinases (MMPs), but their range of activities has now been found to be broader as it includes the inhibition of several of the disintegrin-metalloproteinases, ADAMs and ADAMTSs. TIMPs are therefore key regulators of the metalloproteinases that degrade the extracellular matrix and shed cell surface molecules. Structural studies of TIMP-MMP complexes have elucidated the inhibition mechanism of TIMPs and the multiple sites through which they interact with target enzymes, allowing the generation of TIMP variants that selectively inhibit different groups of metalloproteinases. Engineering such variants is complicated by the fact that TIMPs can undergo changes in molecular dynamics induced by their interactions with proteases. TIMPs also have biological activities that are independent of metalloproteinases; these include effects on cell growth and differentiation, cell migration, anti-angiogenesis, anti- and pro-apoptosis, and synaptic plasticity. Receptors responsible for some of these activities have been identified and their signaling pathways have been investigated. A series of studies using mice with specific TIMP gene deletions has illuminated the importance of these molecules in biology and pathology.

Endothelial progenitor cells (EPCs) mobilized and activated by neurotrophic factors may contribute to pathologic neovascularization in diabetic retinopathy

Diabetic retinopathy is characterized by pathological retinal neovascularization. Accumulating evidence has indicated that high levels of circulating endothelial progenitor cells (EPCs) are an important risk factor for neovascularization. Paradoxically, the reduction and dysfunction of circulating EPCs has been extensively reported in diabetic patients. We hypothesized that EPCs are differentially altered in the various vasculopathic complications of diabetes mellitus, exhibiting distinct behaviors in terms of angiogenic response to ischemia and growth factors and potentially playing a potent role in motivating vascular precursors to induce pathological neovascularization. Circulating levels of EPCs from diabetic retinopathy patients were analyzed by flow cytometry and by counting EPC colony-forming units, and serum levels of neurotrophic factors were measured by enzyme-linked immunosorbent assay. We found increased levels of nerve growth factor and brain-derived neurotrophic factor in the blood of diabetic retinopathy patients; this increase was correlated with the levels of circulating EPCs. In addition, we demonstrated that retinal cells released neurotrophic factors under hypoxic conditions to enhance EPC activity in vitro and to increase angiogenesis in a mouse ischemic hindlimb model. These results suggest that neurotrophic factors may induce neoangiogenesis through EPC activation, leading to the pathological retinal neovascularization. Thus, we propose that neovascularization in the ischemic retina might be regulated by overexpression of neurotrophic factors.

Albumin mediates PPAR-gamma or C/EBP-alpha-induced phenotypic changes in pancreatic stellate cells

Activation of quiescent hepatic stellate cells (HSCs) into myofibroblast-like cells is a key event of liver fibrosis, and adipogenic transcription factors, PPAR-gamma and C/EBP-alpha, reverse HSC activation. As albumin was reported to maintain the quiescent phenotype of stellate cells, we examined whether it plays a role in PPAR-gamma and C/EBP-alpha-mediated effects. Pancreatic stellate cells (PSCs) were isolated from rat pancreas and used in their culture-activated phenotype. Forced expression of PPAR-gamma or C/EBP-alpha in PSCs increased albumin mRNA and protein levels by >2.5-fold, which is accompanied with increased C/EBP-beta binding to albumin promoter. PPAR-gamma and C/EBP-alpha also induced a phenotypic switch from activated to quiescent cells and, interestingly, suppression of albumin using short-hairpin RNA (shRNA) blocked their effects. Therefore, our findings suggest that albumin may be a downstream effector of PPAR-gamma and C/EBP-alpha in PSCs and that it can be an attractive molecular target for anti-fibrotic therapies.

TIMPs and cardiac remodeling: 'Embracing the MMP-independent-side of the family'

Unraveling the biological role of tissue inhibitors of metalloproteinases (TIMPs) during cardiac remodeling and the progression of heart failure has proven to be an enormous challenge. Remodeling of the cardiac extracellular matrix (ECM), regulated by matrix metalloproteinases (MMPs) and their endogenous inhibitors, TIMPs, is a well-established paradigm in cardiac health and disease. Originally, TIMPs were thought to function exclusively as endogenous inhibitors of MMP activity, thereby fine-tuning MMP-mediated ECM degradation and numerous related processes. However, during the last two decades, the concept of MMP-independent TIMP-mediated receptor signaling and regulation of cell fate has emerged. Although our current knowledge is still limited, in this review, we highlight some of the novel data, illustrating the MMP-independent biological properties of the four TIMP family members. Moreover, we discuss how these cell-specific insights may contribute to the process of cardiac remodeling, disease and failure. Finally, we identify where additional research is needed that will codetermine the possible future of TIMPs as therapeutic targets.

Vascular regression and survival are differentially regulated by MT1-MMP and TIMPs in the aortic ring model of angiogenesis

This study was designed to investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) in the reabsorption of neovessels in collagen gel cultures of rat and mouse aortic rings. Aortic angiogenesis was associated with collagen lysis and production of the matrix-degrading enzymes MMP-2, MMP-9, and membrane-type MMP (MT1-MMP, or MMP-14). Vascular growth and regression were not affected by disruption of MMP-2 or MMP-9. In addition, no effect on vascular regression was observed by blocking plasmin, a protease implicated in the activation of MMPs, with epsilon-aminocaproic acid or by adding plasminogen, which caused a modest increase in vascular proliferation. Conversely, angiogenesis was blocked and vessels stabilized by inhibiting MT1-MMP with neutralizing antibodies, TIMP-2, TIMP-3, or TIMP-4. TIMP-1, which blocks MMP-2 and MMP-9 but is a poor inhibitor of MT1-MMP, had no antiangiogenic effect. However, TIMP-1 prolonged the survival of neovessels following angiogenesis. Vascular regression was accelerated in aortic cultures from TIMP-1- and TIMP-2-deficient mice. The vascular survival effect of anti-MT1-MMP antibodies and TIMPs with MT1-MMP inhibitory activity was associated with complete inhibition of collagen lysis. In contrast, TIMP-1 had no anticollagenolytic effect. These results indicate that MT1-MMP plays a critical role not only in angiogenesis but also in vascular regression and demonstrate that TIMPs with anti-MT1-MMP activity have opposite effects on angiogenic outcomes depending on the stage of the angiogenic process. This study also suggests the existence of a TIMP-1-mediated alternate pathway of vascular survival that is unrelated to MT1-MMP inhibitory activity.

Antiangiogenic drugs: current knowledge and new approaches to cancer therapy

Angiogenesis--process of new blood-vessel growth from existing vasculature--is an integral part of both normal developmental processes and numerous pathologies such as cancer, ischemic diseases and chronic inflammation. Angiogenesis plays a crucial role facilitating tumour growth and the metastatic process, and it is the result of a dynamic balance between proangiogenic and antiangiogenic factors. The potential to block tumour growth and metastases by angiogenesis inhibition represents an intriguing approach to the cancer treatment. Angiogenesis continues to be a topic of major scientific interest; and there are currently more antiangiogenic drugs in cancer clinical trials than those that fit into any other mechanistic category. Based on preclinical studies, researchers believe that targeting the blood vessels which support tumour growth could help treatment of a broad range of cancers. Angiogenic factors or their receptors, endothelial cell proliferation, matrix metalloproteinases or endothelial cell adhesion, are the main targets of an increasing number of clinical trials approved to test the tolerance and therapeutic efficacy of antiangiogenic agents. Unfortunately, contrary to initial expectations, it has been described that antiangiogenic treatment can cause different toxicities in cancer patients. The purpose of this article is to provide an overview of current attempts to inhibit tumour angiogenesis for cancer therapy.

Endothelial signaling in paracellular and transcellular leukocyte transmigration

As the primary physical barrier between blood and tissue compartments within the body, blood vessel endothelial cells and integrity of the cell junctions connecting them must be carefully regulated to support leukocyte transendothelial migration only when necessary. Leukocytes utilize two independent routes across the endothelium: the paracellular route involves migration in-between adjacent endothelial cells and requires the transient disassembly of endothelial cell junctions, while the transcellular route occurs directly through an individual endothelial cell, likely requiring the formation of a channel or pore. In this review, I will first summarize the signaling events that are transduced by leukocyte engagement of endothelial cell-surface receptors like ICAM-1 and VCAM-1. Some of these signals include activation of GTPases, production of reactive oxygen species, and phosphorylation of target proteins. These signaling pathways converge to cause junctional disruption, cytoskeletal remodeling, and/or the membrane fusion events that are associated with leukocyte transendothelial migration. The review will conclude with a detailed discussion of the newly characterized transmigratory cup structure, and the recent advances made towards understanding the mechanisms of transcellular transendothelial migration.

Ascorbate-induced osteoblast differentiation recruits distinct MMP-inhibitors: RECK and TIMP-2

The bone formation executed by osteoblasts represents an interesting research field both for basic and applied investigations. The goal of this work was to evaluate the molecular mechanisms involved during osteoblast differentiation in vitro. Accordingly, we demonstrated that, during the osteoblastic differentiation, TIMP-2 and RECK presented differential expressions, where RECK expression was downregulated from the 14th day in contrast with an increase in TIMP-2. Concomitantly, our results showed a temporal regulation of two major signaling cascades during osteoblast differentiation: proliferation cascades in which RECK, PI3 K, and GSK-3beta play a pivotal role and latter, differentiation cascades with participation of Ras, Rho, Rac-1, PKC alpha/beta, and TIMP-2. Furthermore, we observed that phosphorylation level of paxillin was downregulated while FAK(125) remained unchangeable, but active during extracellular matrix (ECM) remodeling. Concluding, our results provide evidences that RECK and TIMP-2 are involved in the control of ECM remodeling in distinct phases of osteoblast differentiation by modulating MMP activities and a multitude of signaling proteins governs these events.

TGF-beta signaling preserves RECK expression in activated pancreatic stellate cells

Activated pancreatic stellate cells (PSCs) play a pivotal role in the pathogenesis of pancreatic fibrosis, but the detailed mechanism for dysregulated accumulation of extracellular matrix (ECM) remains unclear. Cultured rat PSCs become activated by profibrogenic mediators, but these mediators failed to alter the expression levels of matrix metalloproteinases (MMPs) to the endogenous tissue inhibitors of metalloproteinases (TIMPs). Here, we examined the expression of RECK, a novel membrane-anchored MMP inhibitor, in PSCs. Although RECK mRNA levels were largely unchanged, RECK protein expression was barely detected at 2, 5 days after plating PSCs, but appeared following continued in vitro culture and cell passage which result in PSC activation. When PSCs at 5 days after plating (PSCs-5d) were treated with pepstatin A, an aspartic protease inhibitor, or TGF-beta1, a profibrogenic mediator, RECK protein was detected in whole cell lysates. Conversely, Smad7 overexpression or suppression of Smad3 expression in PSCs after passage 2 (PSCs-P2) led to the loss of RECK protein expression. These findings suggest that RECK is post-translationally processed in pre-activated PSCs but protected from proteolytic degradation by TGF-beta signaling. Furthermore, collagenolytic activity of PSCs-5d was greatly reduced by TGF-beta1, whereas that of PSCs-P2 was increased by anti-RECK antibody. Increased RECK levels were also observed in cerulein-induced acute pancreatitis. Therefore, our results suggest for the first time proteolytic processing of RECK as a mechanism regulating RECK activity, and demonstrate that TGF-beta signaling in activated PSCs may promote ECM accumulation via a mechanism that preserves the protease inhibitory activity of RECK.

Effects of green tea polyphenol on methylation status of RECK gene and cancer cell invasion in oral squamous cell carcinoma cells

RECK is a novel tumour suppressor gene that negatively regulates matrix metalloproteinases (MMPs) and inhibits tumour invasion, angiogenesis and metastasis. In the present study, we investigated the effects of epigallocatechin-3-gallate (EGCG), a major polyphenol in green tea, on the methylation status of the RECK gene and cancer invasion in oral squamous cell carcinoma cell lines. Our results showed that treatment of oral cancer cells with EGCG partially reversed the hypermethylation status of the RECK gene and significantly enhanced the expression level of RECK mRNA. Inhibition of MMP-2 and MMP-9 levels was also observed in these cells after treatment with EGCG. Interestingly, EGCG significantly suppressed cancer cell-invasive ability by decreasing the number of invasive foci (P<0.0001) as well as invasion depth (P<0.005) in three-dimensional collagen invasion model. Although further investigation is required to assess the extent of contribution of RECK on MMPs to the suppression of invasive behaviour, these results support the conclusion that EGCG plays a key role in suppressing cell invasion through multiple mechanisms, possibly by demethylation effect on MMP inhibitors such as RECK.

TIMP-2 disrupts FGF-2-induced downstream signaling pathways

We have previously reported that tissue inhibitor of metalloproteinases-2 (TIMP-2), an endogenous inhibitor of matrix metalloproteinase, modulates angiogenic responses through the MMP inhibition-independent activity. In this study, we investigate the molecular mechanisms of TIMP-2-mediated growth inhibition in response to fibroblast growth factor-2 (FGF-2). Pre-treatment with a protein tyrosine phosphatase inhibitor orthovanadate or expression of a dominant negative Shp-1 mutant fails to induce TIMP-2 inactivation of FGF-2 signaling pathways in human microvascular endothelial cells. We also show that TIMP-2 inhibition of FGF-2-induced p42/44(MAPK) activation and cell proliferation is associated with TIMP-2 binding to integrin alpha3beta1 on endothelial cell surfaces, as demonstrated by use of anti-integrin alpha3 or beta1 blocking antibodies, or disruption of integrin alpha3 expression by siRNA. Collectively, our results indicate that TIMP-2 inhibits FGF-2 signaling pathways through association with integrin alpha3beta1 and Shp-1-dependent inhibition of p42/44(MAPK) signaling, which in turn, results in suppression of FGF-2-stimulated endothelial cell mitogenesis.

Tissue inhibitors of metalloproteinases in cell signaling: metalloproteinase-independent biological activities

Over the past 20 years, the tissue inhibitors of metalloproteinases (TIMPs) have been implicated in direct regulation of cell growth and apoptosis. However, the mechanisms of these effects have been controversial. Recent work by several laboratories has identified specific signaling pathways and cell surface binding partners for members of the TIMP family. TIMP-2 binding to the integrin alpha(3)beta(1) is the first description of a cell surface receptor for a TIMP family member. TIMP-2 has been shown to induce gene expression, to promote G(1) cell cycle arrest, and to inhibit cell migration. TIMP-1 binding to CD63 inhibits cell growth and apoptosis. These new findings suggest that TIMPs are multifunctional and can act either directly through cell surface receptors or indirectly through modulation of protease activity to direct cell fate. The emerging concept is that TIMPs function in a contextual fashion so that the mechanism of action depends on the tissue microenvironment.

Matrix metalloproteinases-1 and -2, and tissue inhibitor of metalloproteinase-2 production is abnormal in bone marrow stromal cells of multiple myeloma patients

We have investigated the production of metalloproteinases (MMP-1, MMP-2, MMP-9) and tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) in bone marrow stromal cells (BMSCs) of patients with multiple myeloma (MM) and a healthy control. The new findings of this paper is that BMSCs of the MM patients exhibited intrinsic MMP-1, MMP-2 and TIMP-2 overproduction. Production of MMP-1, TIMP-2 and activation of MMP-2 was additionally enhanced in co-cultures of BMSCs with RPMI8226 cells. The ratio between MMP-2 and TIMP-2 was significantly higher in BMSCs of the MM patients than in control. BMSCs of both the control and the MM patients exhibited the presence of MMP-9 latent form, but in co-cultures RPMI8226 cells were the main producers of this metalloproteinase.

The tumor microenvironment: regulation by MMP-independent effects of tissue inhibitor of metalloproteinases-2

Proteolytic remodeling of the extracellular matrix is an important component of disease progression in many chronic disease states and is the initiating event in the formation of the tumor microenvironment in cancer. It is the balance of extracellular matrix degrading enzymes, the matrix metalloproteinases (MMPs) and their endogenous inhibitors that determine the extent of tissue remodeling. Unchecked MMP activity can result in significant tissue damage, facilitate disease progression and is associated with host responses to pathologic injury such as angiogenesis and inflammation. The tissue inhibitors of metalloproteinases (TIMPs) have been shown to regulate MMP activity. However, recent findings demonstrate that the tissue inhibitor of metalloproteinases-2 (TIMP-2) inhibits the mitogenic response of human microvascular endothelial cells to growth factors, such as VEGF-A and FGF-2 in vitro and angiogenesis in vivo. The mechanism of this effect is independent of metalloproteinase inhibition. Our lab is the first to demonstrate a cell-surface signaling receptor for a member of the TIMP family and suggest that TIMP-2 functions to regulate cellular responses to growth factors. These new findings are discussed in terms of a model of TIMP-2 regulation of cellular functions in the tumor microenvironment.

Metastasis suppressors and the tumor microenvironment

The most dangerous attribute of cancer cells is their ability to metastasize. Throughout the process of metastasis, tumor cells interact with other tumor cells, host cells and extracellular molecules. This brief review explores how a new class of molecules – metastasis suppressors – regulate tumor cell–microenvironmental interactions. Data are presented which demonstrate that metastasis suppressors act at multiple steps of the metastatic cascade. A brief discussion for how metastasis suppressor regulation of cellular interactions might be exploited is presented.

Recklessness as a hallmark of aggressive cancer

Cancer recurrence after surgical treatment is a major concern for patients and doctors. Understanding what makes tumors prone to recurrence would be an important step toward its prevention. Accumulating evidence indicates that the level of membrane-associated protease regulator reversion-inducing cysteine-rich protein with Kazal motifs (RECK) expressed in tumor tissue is a good prognostic indicator in several common cancers. Certain members of the matrix metalloproteinase family are often upregulated in advanced cancers and are known to play important roles in tumor angiogenesis, invasion and metastasis. RECK negatively regulates several matrix metalloproteinases. Therefore, RECK itself may well be considered a promising tool or target molecule to be activated in cancer therapy. Here we review the recent advances in RECK research and discuss some of the important issues to be addressed in future studies.

Alteration of extracellular matrix modulators after nonablative laser therapy in skin rejuvenation

BACKGROUND

Nonablative laser therapy is widely practised for skin rejuvenation, which stimulates collagen production and dermal matrix remodelling. Matrix remodelling is primarily modulated by a coordinated action of matrix metalloproteinases (MMPs) and their inhibitors, but the effects of nonablative lasers on these matrix modulators are not fully investigated.

OBJECTIVES

To evaluate the changes in matrix modulators, such as MMP-1, MMP-2, MMP-3, MMP-9 and MT1-MMP, and their inhibitors (TIMP-1, TIMP-2 and RECK in particular), after nonablative laser treatments of human facial skin.

METHODS

Twenty-four adult volunteers received a series of four nonablative laser treatments separated by 3-week intervals on facial skin. Two-millimetre skin punch biopsies were obtained at baseline and 3 weeks after the last treatment.

RESULTS

Nonablative laser treatments led to a robust increase in two major dermal matrix components, type I collagen and tropoelastin. Among MMPs tested, levels of MMP-2 mRNA were statistically significantly increased, but the amount of active MMP-2 was rather reduced. More importantly, the expression level of RECK was significantly enhanced by laser treatments.

CONCLUSIONS

Clinical outcomes following nonablative laser treatments may result not only from increased biosynthesis but also from decreased degradation, via an induction of RECK expression, of matrix proteins.

Correlation between the protein expression of reversion inducing cysteine rich protein with Kazal motifs and matrix matalloproteinase-9 in esophageal squamous cell carcinoma and its clinical pathological significance

AIM: To investigate the expression of reversion inducing cysteine rich protein with Kazal motifs (RECK) and matrix metalloproteinase-9 (MMP-9) protein and their correlations with the occurrence, development, invasion and metasta-sis of esophageal squamous cell carcinoma.

METHODS: SP immunohistochemical method was used to detect the expression of RECK and MMP-9 protein in 62 cases of esophageal squamous cell carcinoma (EC), 31 cases of adjacent atypical hyperplasia (AH) and 62 cases of normal esophageal epithelium (NE). Statistical analysis was performed using chi-square test.

RESULTS: The protein expression of RECK and MMP-9 were closely correlated with the tumor grade, infiltration and lymph node metastasis in esophageal squamous cell carcinoma (RECK: χ² = 10.422, 8.550, 4.751; MMP-9: χ² = 8.447, 14.333, 5.373; all P < 0.05). The expression rate of RECK protein was increased ordinally in EC, AH and NE which was 59.7%, 71.0%, and 85.5%, respectively, and there was significant difference between every two groups (P < 0.01). However, the expression rate of MMP-9 protein was decreased ordinally in EC, AH and NE, which was 80.6%, 80.6%, 27.4%, respectively, and there was significant difference between every two groups (P < 0.01).

CONCLUSION: RECK and MMP-9 may play important roles in the infiltration, metastasis and carcinomatous changes of mucosal epithelium in esophageal carcinoma. United detection of RECK and MMP-9 can be used in the early diagnosis and prognosis judgement of EC.

[The role of matrix metalloproteinases and tissue inhibitors of metalloproteinases in invasion of tumours of neuroepithelial tissue]

Tumour invasion requires degradation of extracellular matrix components and migration of cells through degraded structures into surrounding tissues. Matrix metalloproteinases (MMP) constitute a family of zinc and calcium-dependent endopeptidases that play a key role in the breakdown of extracellular matrix, and in processing of cytokines, growth factors, chemokines and cell surface receptors. Their activity is regulated at the levels of transcription, activation and inhibition by tissue inhibitors of metalloproteinases (TIMP). Changes in expression of MMP and TIMP are implicated in tumour invasion, because they may contribute to both migration of tumour cells and angiogenesis. Alterations of MMP expression observed in brain tumours arouse interest in the development and evaluation of synthetic matrix metalloproteinase inhibitors as antitumour agents.

A biologically active angiogenesis inhibitor, human serum albumin-TIMP-2 fusion protein, secreted from Saccharomyces cerevisiae

Tissue inhibitor of metalloproteinase-2 (TIMP-2) is an endogenous and bi-functional inhibitor of angiogenesis. TIMP-2 is expressed in an insoluble form in Escherichia coli and secreted at a very low level from yeast. Here, we report on a high level of secretion of TIMP-2 fused with human serum albumin (HSA) from the yeast Saccharomyces cerevisiae. The secreted HSA-TIMP-2 fusion protein (87kDa) was purified to greater than 95% homogeneity. The HSA-TIMP-2 protein inhibited approximately 81% of tube formation of human umbilical vein endothelial cells (HUVECs) when studied at a concentration of 187microM. The systemic administration of HSA-TIMP-2 at 40mg/kg to the C57B1/6 mouse inhibited the growth of B16BL6 tumors. Furthermore, a combination treatment of HSA-TIMP-2 with 5-fluorouracil (50mg/kg) showed significant effects on tumor growth in this model. The high level of secretion of the biologically active angiogenesis inhibitor from S. cerevisiae should facilitate fundamental research and application studies of HSA-TIMP-2, as an attractive candidate for therapeutic agents treating angiogenesis-related diseases.

The role of matrix metalloproteinases in the oral environment

This review focuses specifically on matrix metalloproteinases (MMPs) and their role in physiological and pathological extracellular matrix (ECM) remodeling and degradation processes in the oral environment. A group of enzymes capable of degrading almost all ECM proteins, MMPs contribute to both normal and pathological tissue remodeling. The expression of different MMPs may be upregulated in pathological conditions such as inflammation and tumor invasion. The balance between activated MMPs and tissue inhibitors of metalloproteinases (TIMPs) controls the extent of ECM remodeling. Prior to mineralization, MMPs may participate in the organization of enamel and dentin organic matrix, or they may regulate mineralization by controlling the proteoglycan turnover. There is evidence indicating that MMPs could be involved in the etiology of enamel fluorosis and amelogenesis imperfecta. They seem to play a part in dentinal caries progression, since they have a crucial role in dentin collagen breakdown in caries lesions. MMPs have been identified in pulpal and periapical inflammation and are strongly correlated with periodontal diseases, since they are the major players in collagen breakdown during periodontal tissue destruction. The use of MMP inhibitors could help the prevention and treatment of many MMP-related oral diseases.

Tissue inhibitor of metalloproteinases-2 improves antitumor efficacy of a replicating adenovirus in vivo

Clinical studies of replicating adenoviruses for the treatment of cancer have demonstrated their safety but have yielded disappointing results, indicating the need for new strategies to improve their efficacy. We hypothesized that the efficacy of a replicating adenovirus could be improved by expression of tissue inhibitor of metalloproteinases-2 (TIMP-2), a 21-kDa unglycosylated secretory protein. TIMP-2 specifically inhibits the active forms of a number of matrix metalloproteinases (MMPs) that play a role in the degradation of basement membranes and the extracellular matrix and are therefore involved in the control of the growth, invasion and metastasis of tumor cells, as well as angiogenesis. In addition, TIMP-2 can abrogate tumor growth and angiogenesis by a variety of mechanisms independent of MMP inhibition. In this study, we demonstrate that expression of TIMP-2 enhanced the antitumor efficacy of a replicating adenovirus in vivo, by reducing both tumor growth and angiogenesis.

Downregulation of the RECK-tumor and metastasis suppressor gene in glioma invasiveness

Invasive behavior is the pathological hallmark of malignant gliomas, being responsible for the failure of surgery, radiation, and chemotherapy. Matrix metalloproteinases (MMPs) are essential for proper ECM remodeling and invasion. The tumor and metastasis suppressor RECK protein regulates at least three members of the MMPs family: MMP-2, MMP-9, and MT1-MMP. In order to mimic the in vivo invasion process, A172 and T98G, respectively, non-invasive and invasive human glioblastoma cell lines, were cultured onto uncoated (control) or type I collagen gel-coated surface, and maintained for up to 7 days to allow establishment of the invasive process. We show that the collagen substrate causes decreased growth rates and morphological alterations correlated with the invasive phenotype. Electronic transmission microscopy of T98G cells revealed membrane invaginations resembling podosomes, which are typically found in cells in the process of crossing tissue boundaries, since they constitute sites of ECM degradation. Real time PCR revealed higher RECK mRNA expression in A172 cells, when compared to T98G cells and, also, in samples obtained from cultures where the invasive process was fully established. Interestingly, the collagen substrate increases RECK expression in A172 cells and the same tendency is displayed by T98G cells. MMPs-2 and -9 displayed higher levels of expression and activity in T98G cells, and their activities are also upregulated by collagen. Therefore, we suggest that: (1) RECK downregulation is critical for the invasiveness process displayed by T98G cells; (2) type 1 collagen could be employed to modulate RECK expression in glioblastoma cell lines. Since a positive correlation between RECK expression and patients survival has been noted in several types of tumors, our results may contribute to elucidate the complex mechanisms of malignant gliomas invasiveness.

Gene and protein characteristics reflect functional diversity of CD56dim and CD56bright NK cells

Recent findings underline the role of NK cell subsets in regulating adaptive immunity. To define characteristics of NK cell subpopulations, purified CD56(dim) and CD56(bright) NK cells were analyzed by using gene chip arrays covering more than 39,000 transcripts. Gene profiling revealed resting NK cells to differ in respect to 473 transcripts with 176 exclusively expressed in CD56(dim) and 130 solely in CD56(bright) NK cells. Results were compared with array analyses using mRNA obtained from activated CD56(dim) and CD56(bright) NK cells. In this approach, NK cell receptors, cytolytic molecules, adhesion structures, and chemokine ligands showed differential expression patterns in the two subpopulations. These data were validated using FACS, RT-qPCR, or cytokine bead array (CBA) techniques. Cytokines produced by CD56(dim) and CD56(bright) NK cells were determined using a protein array covering 79 different bioactive mediators. GDNF, IGFBP-1, EGF, and TIMP-2 were detected in both subsets. In contrast, IGFBP-3 and IGF-1 were mainly produced by CD56(dim), while GM-CSF, TARC, and TGFbeta3 were expressed by CD56(bright) NK cells. In summary, we report new characteristic features of CD56(dim) and CD56(bright) NK cells, further underscoring that they represent independent populations with functionally diverse capabilities. The information on NK cells generated in this study will help to define corresponding NK cell populations in other species that lack CD56 expression on NK cells, such as mice. This will subsequently lead to the establishment of suitable animal models for detailed analysis of NK cell populations in vivo.

Ghrelin inhibits angiotensin II-induced migration of human aortic endothelial cells

Ghrelin, the endogenous ligand for the GH secretagogue receptor, is produced by the oxyntic cells of the stomach and is involved in the regulation of energy balance. However, an increasing number of direct ghrelin cardiovascular effects, and, among them, high ghrelin binding in atherosclerotic coronary arteries, are being reported. We investigated whether ghrelin affects migration of human aorta endothelial cells (HAEC). HAEC bound ghrelin in specific, saturable manner. Ghrelin, as such, did not affect HAEC migration, however it inhibited the angiotensin II-induced migration, and this effect was inhibited by the antagonist (D-Lys(3))-GHRP-6. In HAEC, ghrelin elicited increased intracellular concentration of cAMP that was involved in its effect on AngII-induced HAEC migration, as the AMP cyclase inhibitor SQ22.536 and PKA inhibitor KT5720, respectively, inhibited and blunted it. These findings suggest a role of ghrelin in the control of endothelial cell migration and its possible involvement in vascular changes present in disorders characterized by low plasma ghrelin.

TIMP-2 upregulates RECK expression via dephosphorylation of paxillin tyrosine residues 31 and 118

We previously demonstrated that TIMP-2 increases the association of Crk with C3G and via subsequent activation of Rap1 enhances the expression of RECK, a membrane-anchored MMP inhibitor. In the present study, we investigate the mechanism of how the TIMP-2 signal is transduced from the alpha3beta1 integrin receptor to the Crk-C3G-Rap1 molecular complex. TIMP-2 treatment of human microvascular endothelial cells (hMVECs) increased the phosphorylation levels of Src at Tyr-527, the negative regulatory site, through enhanced association of Src with Csk. This results in the reduction of Src kinase activity and dephosphorylation of paxillin at Tyr-31/118, the target sites for Src kinase phosphorylation and also the binding sites for the downstream effector Crk. Such TIMP-2 effects accompany the disassembly of paxillin-Crk-DOCK180 molecular complex and, in turn, Rac1 inactivation. On the contrary, levels of paxillin-Crk-C3G complex formation are not reduced, rather slightly increased, which is consistent with our previous finding. Therefore, TIMP-2-mediated inhibition of Src kinase activity leads to the signaling switch from Rac1 to Rap1, thereby leading to enhanced RECK expression.

Reduced expression of vascular endothelial growth factor paralleled with the increased angiostatin expression resulting from the upregulated activities of matrix metalloproteinase-2 and -9 in human type 2 diabetic arterial vasculature

Impaired angiogenesis could contribute to the increased incidence of coronary and peripheral artery disease in diabetic patients. Angiogenesis is initiated by vascular endothelial growth factor (VEGF), a potent angiogenic cytokine, and suppressed by angiostatin, which is generated by matrix metalloproteinase (MMP)-2 and -9 through proteolytic cleavage of plasminogen. We hypothesized that MMP-2 and -9 were upregulated in the diabetic vasculature, resulting in increased angiostatin production and reduced blood vessel formation. In diabetic internal mammary artery samples (n=32) collected from patients undergoing coronary artery bypass grafting surgery, capillary density was only 30% of that in the nondiabetic vessels (n=32), whereas VEGF expression was reduced by 48%. Diabetes upregulated the expression and the gelatinolytic activity of MMP-2 and -9. Active MMP-2 and -9 were released from diabetic arteries, but not from nondiabetic vessels, during phenylephrine-induced vasoconstriction. Diabetes enhanced transcription and protein expression of tissue inhibitor of MMP (TIMP)-1 but had an opposite effect on TIMP-2. In diabetic vessels angiostatin was increased by 62% and was positively correlated with the activities of MMP-2 and -9 (r2=0.806 and 0.742, respectively). This report indicated a strong correlation between the upregulation of MMP-2 and MMP-9 and the increased angiostatin expression in the human diabetic arterial vasculature. The enhanced angiostatin production with a reduced VEGF formation may explain the pathogenesis of impaired angiogenesis in diabetes mellitus.

TIMP-2 promotes cell spreading and adhesion via upregulation of Rap1 signaling

We previously demonstrated that TIMP-2 treatment of human microvascular endothelial cells (hMVECs) activates Rap1 via the pathway of paxillin-Crk-C3G. Here, we show that TIMP-2 overexpression in hMVECs by adenoviral infection enhances Rap1 expression, leading to further increase in Rap1-GTP. TIMP-2 expression, previously reported to inhibit cell migration, also leads to cell spreading accompanied with increased cell adhesion. HMVECs stably expressing Rap1 display a similar phenotype as hMVECs-TIMP-2, whereas the expression of inactive Rap1 mutant, Rap1(38N), leads to elongated appearance with greatly reduced cell adhesion. Furthermore, the phenotype of hMVECs-Rap1(38N) was not reversed by TIMP-2 overexpression. TIMP-2 greatly promotes the association of Rap1 with actin. Therefore, these findings suggest that TIMP-2 mediated alteration in cell morphology requires Rap1, TIMP-2 may recruit Rap1 to sites of actin cytoskeleton remodeling necessary for cell spreading, and enhanced cell adhesion by TIMP-2 expression may hinder cell migration.

The effect of thrombin on ACL fibroblast interactions with collagen hydrogels

Premature loss of provisional scaffold formation has been identified as one of the factors responsible for poor healing of intraarticular tissues. To address this deficiency, substitute provisional scaffolds are being developed. The function of these scaffolds can be enhanced by the addition of specific extracellular matrix proteins. In this study, it was hypothesized that the addition of thrombin to a provisional scaffold material would result in increases in cell proliferation, collagen production, and cell migration within the scaffold. These three parameters are thought to be critical components of wound healing. Gels containing fibrin and collagen supplemented with either 0, 10.5, 21, or 42 U/mL of thrombin were placed in contact with explants of tissue from the anterior cruciate ligament. The addition of thrombin stimulated cell migration at low concentrations and impaired migration at higher concentrations, and had no significant effect on cell proliferation or collagen production. The use of all concentrations of thrombin resulted in mechanically weaker gels. Thus, the use of thrombin to optimize a collagen-platelet rich plasma (PRP) provisional scaffold must be done with caution, and use of high concentrations of thrombin (>42 IU/mL) should be avoided specifically in situations where gel strength or cell ingrowth is important. Use of low concentrations of thrombin (10.5 IU/mL) may be beneficial in applications where a faster set time and enhanced cell migration are desirable and the gel mechanical strength is of secondary importance.

Pericellular proteases in angiogenesis and vasculogenesis

Pericellular proteases play an important role in angiogenesis and vasculogenesis. They comprise (membrane-type) matrix metalloproteinases [(MT-)MMPs], serine proteases, cysteine cathepsins, and membrane-bound aminopeptidases. Specific inhibitors regulate them. Major roles in initiating angiogenesis have been attributed to MT1-matrix metalloproteinase (MMP), MMP-2, and MMP-9. Whereas MT-MMPs are membrane-bound by nature, MMP-2 and MMP-9 can localize to the membrane by binding to alphavbeta3-integrin and CD44, respectively. Proteases switch on neovascularization by activation, liberation, and modification of angiogenic growth factors and degradation of the endothelial and interstitial matrix. They also modify the properties of angiogenic growth factors and cytokines. Neovascularization requires cell migration, which depends on the assembly of protease-protein complexes at the migrating cell front. MT1-MMP and urokinase (u-PA) form multiprotein complexes in the lamellipodia and focal adhesions of migrating cells, facilitating proteolysis and sufficient support for endothelial cell migration and survival. Excessive proteolysis causes loss of endothelial cell-matrix interaction and impairs angiogenesis. MMP-9 and cathepsin L stimulate the recruitment and action of blood- or bone-marrow-derived accessory cells that enhance angiogenesis. Proteases also generate fragments of extracellular matrix and hemostasis factors that have anti-angiogenic properties. Understanding the complexity of protease activities in angiogenesis contributes to recognizing new targets for stimulation or inhibition of neovascularization in disease.

Shp-1 mediates the antiproliferative activity of tissue inhibitor of metalloproteinase-2 in human microvascular endothelial cells

The tissue inhibitors of metalloproteinases (TIMPs) regulate matrix metalloproteinase activity required for cell migration/invasion associated with cancer progression and angiogenesis. TIMPs also modulate cell proliferation in vitro and angiogenesis in vivo independent of their matrix metalloproteinase inhibitory activity. Here, we show that TIMP-2 mediates G1 growth arrest in human endothelial cells through de novo synthesis of the cyclin-dependent kinase inhibitor p27Kip1. TIMP-2-mediated inhibition of Cdk4 and Cdk2 activity is associated with increased binding of p27Kip1 to these complexes in vivo. Protein-tyrosine phosphatase inhibitors or expression of a dominant negative Shp-1 mutant ablates TIMP-2 induction of p27Kip1. Finally, angiogenic responses to fibroblast growth factor-2 and vascular endothelial growth factor-A in "motheaten viable" Shp-1-deficient mice are resistant to TIMP-2 inhibition, demonstrating that Shp-1 is an important negative regulator of angiogenesis in vivo.

Expression of reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) as a prognostic indicator in gastric cancer

In this study the expression levels of reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) in gastric cancer cell lines and tissues have been analysed in order to assess their value as a prognostic indicator. The expressions of RECK, activated matrix metalloproteinase (MMP)-7, and vascular endothelial growth factor (VEGF) in gastric cancer tissues and cell lines were evaluated by Western blot analysis; and MMP-2 and MMP-9 were evaluated by gelatin zymography. RECK expression in the context of gastric cancer was also compared with various clinicopathologic parameters and compared to the expression of activated MMP-7, MMP-2, and MMP-9. Fifty-two percent of the 102 gastric cancer tissues and 81.8% of the 11 gastric cancer cell lines exhibited reduced RECK expression. We also detected a significant inverse correlation between RECK expression and macroscopic tumour growth (P=0.018), lymphatic invasion (P=0.018), lymph node metastasis (P=0.000), stage (P=0.000), and MMP-9 (P=0.039). No correlation between RECK expression and MMP-7 and MMP-2, VEGF were detected. Our data strongly supports the hypothesis that RECK is a suppressor of malignancy, and constitutes a good prognostic indicator in gastric cancer.

Matrix metalloproteinases and angiogenesis

Matrix metalloproteinases (MMPs) are a family of enzymes that proteolytically degrade various components of the extracellular matrix (ECM). Angiogenesis is the process of forming new blood vessels from existing ones and requires degradation of the vascular basement membrane and remodeling of the ECM in order to allow endothelial cells to migrate and invade into the surrounding tissue. MMPs participate in this remodeling of basement membranes and ECM. However, it has become clear that MMPs contribute more to angiogenesis than just degrading ECM components. Specific MMPs have been shown to enhance angiogenesis by helping to detach pericytes from vessels undergoing angiogenesis, by releasing ECM-bound angiogenic growth factors, by exposing cryptic proangiogenic integrin binding sites in the ECM, by generating promigratory ECM component fragments, and by cleaving endothelial cell-cell adhesions. MMPs can also contribute negatively to angiogenesis through the generation of endogenous angiogenesis inhibitors by proteolytic cleavage of certain collagen chains and plasminogen and by modulating cell receptor signaling by cleaving off their ligand-binding domains. A number of inhibitors of MMPs that show antiangiogenic activity are already in early stages of clinical trials, primarily to treat cancer and cancer-associated angiogenesis. However, because of the multiple effects of MMPs on angiogenesis, careful testing of these MMP inhibitors is necessary to show that these compounds do not actually enhance angiogenesis.