Tissue inhibitor of metalloproteinases-2 inhibits bFGF-induced human microvascular endothelial cell proliferation

The role of angiogenesis in solid tumours: an overview

Angiogenesis is the physiological process of the formation of new blood vessels from pre-existing ones. Multiple molecules regulate angiogenesis, such as the vascular endothelial growth factor, angiopoietins, the fibroblast growth factor, the platelet-derived growth factor and the transforming growth factor-beta. Angiogenesis plays an important role in the growth, progression and metastasis of a tumour. Inhibiting the angiogenic process or targeting existing tumour vessels can be used for treatment of tumours as an alternative or in parallel with conventional chemotherapy. Many anti-angiogenic factors are under investigation and some are already being used in clinical practice with various results.

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.

Tissue inhibitor of metalloproteinase-4 is elevated in early-stage breast cancers with accelerated progression and poor clinical course

An increasing number of breast cancer patients are diagnosed with small, localized, early-stage tumors. These patients are typically thought to have a good prognosis for long-term disease-free survival, but epidemiological studies indicate that up to 30% may have a recurrence within 3 to 5 years of diagnosis. Identifying patients with a high risk of recurrence and/or progression is important because they could be more aggressively treated at diagnosis to improve their chances for disease-free survival. Recent evidence suggests that elevated levels of the matrix metalloproteinase inhibitor, tissue inhibitor of metalloproteinase (TIMP)-4, are associated with malignant progression of ductal carcinoma in situ, a precancerous lesion. To examine the association of TIMP-4 with survival outcomes, we conducted a retrospective immunohistochemical analysis of 314 cases from patients with early-stage disease, defined as tumors smaller than 2 cm and no spread to lymph nodes (tumor-node-metastasis staging: T1N0MX). We found that tumors with elevated levels of TIMP-4 were correlated with a reduced probability of long-term disease-free survival, especially in patients with estrogen receptor-negative tumors. Our findings prompt further evaluation of TIMP-4 as a simple prognostic marker that may help identify patients with early-stage breast cancer who could benefit from more aggressive treatment at diagnosis.

Polymorphisms in tissue inhibitors of metalloproteinases-2 and -3 and breast cancer susceptibility and survival

Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of matrix metalloproteinases which are involved in normal cellular processes and also in cancer development and progression. The purpose of this study was to evaluate polymorphisms in the TIMP-2 and TIMP-3 genes for their associations with breast cancer susceptibility and survival. Using data from the Shanghai Breast Cancer Study, 19 SNPs for each gene were evaluated for associations with breast cancer risk among 1,062 cases and 1,069 controls; associations with disease-free and overall survival were evaluated among the cases. For TIMP-2, women with the rs7501477 TT genotype were 3 times more likely to be breast cancer cases than women with the CC genotype (OR: 2.9, 95% CI: 1.2-7.0). For TIMP-3, women with the rs9609643 AA genotype were 60% less likely to be breast cancer cases than women with the GG genotype (OR: 0.4, 95% CI: 0.2-1.0), whereas women with the rs8136803 TT genotype were 5 times more likely to be cases than women with the GG genotype (OR: 5.1, 95% CI: 1.1-24.3). Further, breast cancer cases with rs8136803 TT were almost 4 times more likely to have decreased disease-free survival (HR: 3.9, 95% CI: 1.4-10.6) and had a trend toward decreased overall survival (HR: 1.9, 95% CI: 0.6-6.1). An important study limitation was that these 3 SNPs (rs7501477, rs9609643, rs8136803) had low minor allele frequencies which resulted in small numbers of homozygote individuals. Genetic variation in the TIMP-2 and TIMP-3 genes may contribute to individual differences in breast cancer susceptibility and survival.

A new direction for cardiac regeneration therapy: application of synergistically acting epicardium-derived cells and cardiomyocyte progenitor cells

BACKGROUND

Adult human epicardium-derived cells (EPDCs), transplanted into the infarcted heart, are known to improve cardiac function, mainly through paracrine protection of the surrounding tissue. We hypothesized that this effect might be further improved if these supportive EPDCs were combined with cells that could possibly supply the ischemic heart with new cardiomyocytes. Therefore, we transplanted EPDCs together with cardiomyocyte progenitor cells that can generate mature cardiomyocytes in vitro.

METHODS AND RESULTS

EPDCs and cardiomyocyte progenitor cells were isolated from human adult atrial appendages, expanded in culture, and transplanted separately or together into the infarcted mouse myocardium (total cell number, 4x10(5)). Cardiac function was determined 6 weeks later (9.4T MRI). Coculturing increased proliferation rate and production of several growth factors, indicating a mutual effect. Cotransplantation resulted in further improvement of cardiac function compared with single cell-type recipients (P<0.05), which themselves demonstrated better function than vehicle-injected controls (P<0.05). However, in contrast to our hypothesis, no graft-derived cardiomyocytes were observed within the 6-week survival, supporting that not only EPDCs but also cardiomyocyte progenitor cells acted in a paracrine manner. Because injected cell number and degree of engraftment were similar between groups, the additional functional improvement in the cotransplantation group cannot be explained by an increased amount of secreted factors but rather by an altered type of secretion.

CONCLUSIONS

EPDCs and cardiomyocyte progenitor cells synergistically improve cardiac function after myocardial infarction, probably instigated by complementary paracrine actions. Our results demonstrate for the first time that synergistically acting cells hold great promise for future clinical regeneration therapy.

Regulation of soluble vascular endothelial growth factor receptor 1 secretion from human endothelial cells by tissue inhibitor of metalloproteinase 1

Vascular endothelial growth factor (VEGF) and its soluble receptor (sVEGFR-1) are key regulators in human ovarian angiogenesis. Produced by granulosa and ovarian theca interna cells, VEGF promotes blood vessel growth during follicular development and corpus luteum formation, whereas sVEGFR-1, which is secreted by endothelial cells, functions as an antagonist to VEGF activity by binding it. In order to gain further insights into the regulatory mechanisms of ovarian angiogenesis, the aim of the present study was to analyze the influence of tissue inhibitor of metalloproteinase 1 (TIMP-1), which is actively involved in the degradation and remodeling of the extracellular matrix, on sVEGFR-1 secretion of cultured human umbilical vein endothelial cells. sVEGFR-1 production was determined in the culture supernatant by Sandwich-ELISA. We showed that TIMP-1 produced by human granulosa cells and recombinant human TIMP-1 both significantly increased the production of sVEGFR-1 in endothelial cells. Also, the down-regulation of TIMP-1 expression by RNA interference resulted in a significant reduction of endothelial sVEGFR-1 secretion into the culture medium. Furthermore, TIMP-1 weakly inhibited proliferation of VEGF-stimulated endothelial cells. In conclusion, our results provide evidence that TIMP-1 increases the production of sVEGFR-1 in endothelial cells and thus may reduce VEGF bioavailability, leading to reduced blood vessel growth in the ovary.

Tumour angiogenesis: its mechanism and therapeutic implications in malignant gliomas

Angiogenesis is a key event in the progression of malignant gliomas. The presence of microvascular proliferation leads to the histological diagnosis of glioblastoma multiforme. Tumour angiogenesis involves multiple cellular processes including endothelial cell proliferation, migration, reorganisation of extracellular matrix and tube formation. These processes are regulated by numerous pro-angiogenic and anti-angiogenic growth factors. Angiogenesis inhibitors have been developed to interrupt the angiogenic process at the growth factor, receptor tyrosine kinase and intracellular kinase levels. Other anti-angiogenic therapies alter the immune response and endogeneous angiogenesis inhibitor levels. Most anti-angiogenic therapies for malignant gliomas are in Phase I/II trials and only modest efficacies are reported for monotherapies. The greatest potential for angiogenesis inhibitors may lie in their ability to combine safely with chemotherapy and radiotherapy.

Therapy of head and neck squamous cell carcinoma with replicative adenovirus expressing tissue inhibitor of metalloproteinase-2 and chemoradiation

Recent studies have demonstrated the efficacy of targeted therapy combined with radiotherapy in head and neck squamous cell carcinoma (HNSCC). We hypothesized that a combination treatment including a replicating adenovirus armed with tissue inhibitor of metalloproteinase-2 (TIMP-2), radiation and Cisplatin will augment treatment response and reduce tumor growth in vivo of HNSCC xenografts. Both single-agent (TIMP-2 virus, radiation and Cisplatin) and the combination therapies were evaluated in vitro and in vivo. The efficacy of both single-agent and combination therapies in vivo was determined by monitoring tumor growth and immunohistochemistry. Treatment with replicative Ad-TIMP-2 virus and radiation decreased cell viability in vitro and resulted in an additional antiangiogenic response in vivo. Tumor response rates to treatment with replicative Ad-TIMP-2, radiation, Cisplatin or combination therapies ranged from limited inhibition of tumor growth of the single-agent therapy to a statistically significant additive antitumor response with the combination therapies. Replicative Ad-TIMP-2+radiation+Cisplatin in the SCC1 nude mice demonstrated the greatest response rates in tumor growth and angiogenesis. Combination of Ad-TIMP-2 gene therapy with radiation and the triple treatment group resulted in an augmented therapeutic response. This is the first report of the potential benefits of combining radiation and MMP inhibitor treatment.

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.

Adenovirus-mediated transfer of siRNA against MMP-2 mRNA results in impaired invasion and tumor-induced angiogenesis, induces apoptosis in vitro and inhibits tumor growth in vivo in glioblastoma

Invasive tumors, including gliomas, utilize proteinases to degrade extracellular matrix components and diffuse into the adjacent tissues or migrate toward distant ones. In addition, proteinase activity is required for the formation of new blood vessels within the tumor. Levels of the proteinase matrix metalloproteinase-2 (MMP-2) are highly increased in gliomas. In this study, we examined the effect of the downregulation of MMP-2 via adenovirus-mediated siRNA in gliomas. Here, we show that siRNA delivery significantly decreased levels of MMP-2 in the glioblastoma cell lines U-87 and U-251. U-87 and U-251 cells showed impaired invasion through matrigel as well as decreased migration from tumor spheroids transfected with adenoviral vector expressing siRNA against MMP-2. Additionally, tumor-induced angiogenesis was decreased in in vitro experiments in cultured human microvascular endothelial cells (HMECs) in serum-free conditioned medium of glioblastoma cells transfected with these constructs and co-cultures of glioma cells with HMECs. We also observed decreased angiogenesis in the in vivo dorsal skin-fold chamber model. Moreover, MMP-2 inhibition induced apoptotic cell death in vitro, and suppressed tumor growth of preestablished U-251 intracranial xenografts in nude mice. Thus, specific targeting of MMP-2 may provide a novel, efficient approach for the treatment of gliomas and improve the poor outcomes of patients with these brain tumors.

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.

Why does menopausal hormone therapy lead to irregular uterine bleeding? Changes to endometrial blood vessels

BACKGROUND

Abnormal bleeding is common in hormone therapy (HT) users. We aimed to determine how HT alters endometrial blood vessels and stromal factors known to regulate vascular growth and integrity.

METHODS

Prospective observational study of 165 post-menopausal women in Western Australia. The following were measured in endometrial biopsies: vascular density (vessels/mm(2)), total vessel area (total area enclosed by peripheral vascular immunostaining for perivascular pericytes in mm(2)), total luminal area (mm(2)) and vessel wall area (total vessel area minus luminal area), stromal expression of matrix metalloproteinases (MMP) -1, -3, -9 and -14, their tissue inhibitors (TIMPs) -1-4 and vascular endothelial growth factor (VEGF) by immunohistochemistry.

RESULTS

Total vessel area was greater during bleeding compared with HT users with no bleeding (P = 0.028) or with a prior irregular bleeding (P = 0.039). Total vessel area was greater in non-HT users compared with HT users with no bleeding (P = 0.021). In HT users, vessel luminal area was greater during bleeding compared with HT users with no bleeding (P = 0.030) and vessel wall area was also increased (P = 0.025). During bleeding there was an increase in stromal TIMP-2 staining (P = 0.044). No significant changes in endometrial MMP or VEGF were seen.

CONCLUSIONS

Abnormal bleeding in HT users is associated with changes in endometrial vessel size and in stromal expression of factors known to regulate vascular growth and integrity. These changes may contribute to abnormal bleeding.

Antiangiogenic therapy and surgical practice

Background

Antiangiogenic therapy has become a reality with the recent introduction of bevacizumab, a monoclonal antibody against vascular endothelial growth factor.

Methods

Relevant medical literature from PubMed, National Institute for Health and Clinical Excellence and National Institutes of Health websites to August 2007 was reviewed.

Results and conclusions

Although often described as the fourth modality of treatment after surgery, radiotherapy and chemotherapy, many antiangiogenic drugs have failed to live up to expectations. Nevertheless, research continues and there are reasons to believe that antiangiogenic therapy may yet have a future in the clinical setting.

A critical role for matrix metalloproteinases in liver regeneration

BACKGROUND

Matrix metalloproteinases (MMPs), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) are mediators of liver regeneration. To determine whether MMPs are required for normal hepatic regeneration, we performed 67% hepatectomies on mice treated with a broad-spectrum MMP-inhibitor, and assessed the effect on liver regeneration and urinary MMP activity.

METHODS

Mice were subjected to sham operations, 67% hepatectomy, or 67% hepatectomy plus treatment with the broad-spectrum MMP inhibitor Marimastat. Urine collected preoperatively and for 8 d postoperatively was tested for MMP-2 and MMP-9 activity using zymography. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, bilirubin, TNF-alpha, IL-6, and hepatocyte growth factor levels were measured. Liver sections were analyzed by CD31 immunohistochemistry and microvessel density. Mitotic index and proliferating cell nuclear antigen labeling index were determined.

RESULTS

The mean regenerating liver weight on postoperative day 8 was 0.72 +/- 0.01 grams for the hepatectomy Marimastat group, and 0.83 +/- 0.02 grams for the hepatectomy control group (P < 0.001). Urinary MMP-9 activity was elevated during hepatic regeneration, and decreased on postoperative day 8 when the liver returned to its preoperative mass. In contrast, urine from hepatectomy Marimastat mice, in which liver regeneration was successfully inhibited, showed consistently low levels of MMP-2 and MMP-9 activity. The hepatectomy Marimastat group also exhibited elevated serum IL-6 levels on post-operative day 8, while serum TNF-alpha soluble receptor II levels were unchanged. Hepatocyte growth factor levels were not significantly different between the control hepatectomy and hepatectomy Marimastat groups at days 2, 4, and 8. Liver microvessel density was reduced in the hepatectomy Marimastat group at day 4. Mitotic index and proliferating cell nuclear antigen index were significantly decreased in the Marimastat hepatectomy group at post-operative day 2.

CONCLUSIONS

The broad-spectrum MMP-inhibitor Marimastat inhibits liver regeneration. Microvessel density is reduced at day 4. Furthermore, urinary MMP-9 is elevated during liver regeneration, and this effect is not observed when regeneration is inhibited by the broad-spectrum MMP-inhibitor Marimastat.

Topology of the heterogeneous nature of the extracellular matrix on stochastic modeling of tumor-induced angiogenesis

We have modeled tumor-induced angiogenesis; our model includes the phenomena of the migratory response of endothelial cells (ECs) to tumor angiogenic factors, and the interaction of ECs with the extracellular matrix (ECM). ECs switch between growth, differentiation, motility, or apoptotic behavior in response to the local topology and composition of the ECM. Assuming the ECM medium as a statistically inhomogeneous medium (some area support sprout growth, some not), we show that the ECM can be a natural barrier to angiogenesis. We study vascular network formation for several ECM distributions and topologies, and we find an analogy with percolation. A threshold exists, under which sprouts cannot reach the tumor. During the growth of the vascular network, a competition exists between the attraction exerted by tumor and the preferred path created by the ECM. We also examined the influence of branching on the tumor vascularization. Branching is a natural phenomenon which helps the tumor become vascularized. By increasing the number of sprouts, the vascular network increases the probability of reaching the tumor, as it can explore more pathways. Our simulations show after two branching events, the vascular network is very likely to reach the tumor.

Tissue inhibitor of metalloproteinase 2 and coronary artery lesions in Kawasaki disease

OBJECTIVE

To identify cytokine genes uniquely expressed in peripheral blood mononuclear cells (PBMNCs) in the acute phase of Kawasaki disease (KD) with coronary artery lesions (CALs).

STUDY DESIGN

We screened the mRNA expression levels of PBMNCs from 4 pairs of KD patients with and without CAL using DNA microarray. The result was confirmed by real-time polymerase chain reaction (RT-PCR). The genetic association study was performed to analyze the significance of single nucleotide polymorphisms in the identified gene for the development of CAL in KD patients (184 controls, 144 KD patients with CAL, 64 KD patients without CAL).

RESULTS

The microarray analysis showed that tissue inhibitor of metalloproteinases 2 (TIMP2) was expressed at higher levels in PBMNCs of KD patients with CAL than in KD patients without CAL. Quantitative RT-PCR confirmed that the expression levels were significantly higher in the KD patients with CAL than in those without CAL (P < .05). Among KD patients, TIMP2 promoter polymorphisms were significantly associated with a risk of CAL (P < .01). There was a significant difference in the transcriptional activities between the haplotypes of the TIMP2 promoter polymorphisms by reporter assay using U-937.

CONCLUSIONS

TIMP2 overexpression and the promoter polymorphisms might play a role in the development of CALs.

Opposite effects of high glucose on MMP-2 and TIMP-2 in human endothelial cells

Diabetes mellitus (DM) is a major risk factor for atherosclerosis and causes multiple cardiovascular complications. Although high glucose can induce matrix metalloproteinases (MMPs), its inhibitors and cell apoptosis, little is known about the roles of MMPs in regulating cell apoptosis in response to high glucose. To address this issue, we elucidated the relationship between MMPs, its inhibitors and cell apoptosis in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with medium containing 5.5 mM or 33 mM of glucose in the presence or the absence of ascorbic acid and MMP inhibitors (GM6001 and endogenous tissue inhibitors of MMPs, TIMP-1, and TIMP-2). For detection of cell apoptosis, the cell death detection ELISA assay was used. The results revealed that high glucose-induced apoptosis could be suppressed by ascorbic acid, GM6001 and TIMP-2, but not by TIMP-1. The activities of MMP-2, MMP-9 and its inhibitors, TIMP-1, TIMP-2 after high glucose treatment, were also detected by ELISA method. We found that the activated form of MMP-2, but not MMP-9, was increased, while the level of TIMP-2, but not TIMP-1, was decreased. In Western blot and RT-PCR analysis, the expression of TIMP-2, but not TIMP-1, after high glucose treatment was downregulated, whereas the levels of MMP-2 and -9 proteins and mRNA were not changed. The present study indicated that oxidative stress induced by high glucose might be involved in the opposite effects on MMP-2 activation and TIMP-2 downregulation. This reactive oxygen species (ROS)-dependent MMP-2 activation in turn mediates high glucose-induced cell apoptosis in HUVECs.

Association of TIMP-2 with extracellular matrix exposed to mechanical stress and its co-distribution with periostin during mouse mandible development

Matrix remodeling is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Periostin, originally identified in a mouse osteoblastic library, plays a role in cell adhesion and migration and in mechanical stress-induced matrix remodeling. In this study, we analyzed and compared the distribution patterns of TIMP-2 and periostin during mouse mandible development. Immunohistochemical staining for TIMP-2 and periostin was carried out on serial cryosections obtained from mice at embryonic days 13-16, postnatal day 2 (P2), P35, and 12 weeks of age. TIMP-2 and periostin exhibited a strikingly similar protein distribution during mandible development. From bud to early bell stages of molars, TIMP-2 and periostin were highly expressed on the lingual and anterior sides of the basement membrane and on the adjacent jaw mesenchyme. In pre- and postnatal incisors, the basement membrane of the apical loop and dental follicle was immunostained for TIMP-2 and periostin. At postnatal stages, TIMP-2 and periostin were prominently confined to the extracellular matrix (ECM) of gingival tissues, periodontal ligaments, and tendons (all recipients of mechanical strain). However, periostin was solely detected in the lower portion of the inner root sheath of hair follicles. Gingiva of P2 cultured in anti-TIMP-2 antibody-conditioned medium showed markedly reduced staining of periostin. We suggest that TIMP-2 and periostin are co-distributed on ECM exposed to mechanical forces and coordinately function as ECM modulators.

Matrix metalloproteinases: influence on smooth muscle cells and atherosclerotic plaque stability

Atherosclerotic plaque rupture, with subsequent occlusive thrombosis, is the underlying cause of most cases of sudden cardiac death. Matrix metalloproteinases (MMPs) are thought to mediate the progression of stable atherosclerotic lesions to an unstable phenotype that is prone to rupture through the destruction of strength-giving extracellular matrix (ECM) proteins. Smooth muscle cells secrete and deposit ECM proteins and are, therefore, considered protective against atherosclerotic plaque destabilization. However, similar to inflammatory cells (e.g., macrophages), smooth muscle cells release numerous MMPs that are capable of digesting ECM proteins. Thus, the interaction of smooth muscle cells and MMPs in atherosclerotic plaques is complex and not fully understood. Recently, research into the roles of MMPs and their endogenous inhibitors (tissue inhibitors of metalloproteinases), and their effects on smooth muscle behavior during plaque destabilization has been aided by the development of reproducible animal models of plaque instability. A plethora of studies has demonstrated that MMPs directly modulate smooth muscle behavior with both beneficial and deleterious effects on atherosclerotic plaque stability, in addition to their canonical effects on ECM remodeling. Consequently, broad-spectrum MMP inhibition may inhibit plaque-stabilizing mechanisms, such as smooth muscle cell growth, while conversely retarding ECM destruction and subsequent rupture. Hence the development of selective MMP inhibitors, that spare inhibitory effects on smooth muscle cell function, may be useful therapies to prevent plaque rupture and in this regard MMP-12 appears to be a particularly attractive target.

Proteinase inhibitors and helminth parasite infection

The concept that parasites may utilize proteinase inhibitors to survive within the host has been with us for 100 years. Given that we now know that proteinases are involved in key areas of the host anti-parasite immune response including antigen presentation, effector cell function and tissue dissolution and remodelling, it is somewhat surprising that the proteinase inhibitors of parasite origin have not generally been the subject of intense research effort. There is now substantial evidence to show that nematode parasites utilize these inhibitors to protect themselves from degradation by host proteinases, to facilitate feeding and to manipulate the host response to the parasite. The diversity of the parasite-derived inhibitors is also being revealed and they target the four major proteinase classes, namely serine, cysteine, aspartic and metallo-proteinases. This review summarizes the information available on nematode-derived proteinase inhibitors and what is known of their putative functions. Their potential as targets for immunological control is also addressed.

[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.

ANGIOTENSIN II INCREASES TISSUE-SPECIFIC INHIBITOR OF METALLOPROTEINASE-2 EXPRESSION IN RAT AORTIC SMOOTH MUSCLE CELLS IN VIVO: EVIDENCE OF A PRESSURE-INDEPENDENT EFFECT

1. Angiotensin (Ang) II plays a major role in vascular remodelling. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are involved in the tissue remodelling processes. The aim of the present study was to investigate whether AngII modulates TIMP-2 expression in rat aortic smooth muscle cells in vivo. 2. Angiotensin II (200 ng/kg per min, s.c.) or AngII + losartan (10 mg/kg per day, s.c.) or normal saline was administered continuously by osmotic minipumps to Sprague-Dawley rats for 1 week. In addition, the effect of endogenous AngII on TIMP-2 expression was evaluated in renovascular hypertensive rats (two kidney, one clip (2K1C) and one kidney, one clip (1K1C) models). Control rats (sham 2K1C and sham 1K1C rats) underwent sham-clipping of the left renal artery. At the end of the treatment, plasma renin activity was measured by radioimmunoassay, aortic TIMP-2 mRNA expression was evaluated by real-time polymerase chain reaction and/or northern blotting and protein expression was evaluated by immunohistochemistry. Systolic blood pressure (SBP) was measured twice a week by the tail-cuff method. 3. Exogenous AngII administration produced the expected increase in SBP (P = 0.02) compared with the control saline-treated group. The increase in SBP was abolished in AngII + losartan-treated rats. Administration of AngII caused a significant increase in TIMP-2 expression (P = 0.01) in rat aortic smooth muscle cells that was abolished in AngII + losartan-treated rats. In renovascular hypertensive rats, SBP was higher (P < 0.0001) in 2K1C and 1K1C rats compared with the corresponding sham-operated rats. Plasma renin activity was higher (P < 0.01) in 2K1C rats compared with the other groups. The expression of TIMP-2 was significantly (P < 0.05) increased only in 2K1C rats. 4. Our in vivo data demonstrate that exogenous and endogenous AngII increases TIMP-2 expression in rat aortic smooth muscle cells. This effect is not dependent on the AngII-induced increase in blood pressure and is mediated by angiotensin AT1 receptors.

Tissue inhibitors of metalloproteinases (TIMPs): their biological functions and involvement in oral disease

Several families of enzymes are responsible for the degradation of extracellular matrix (ECM) proteins during the remodeling of tissues. An important family of such enzymes is that of the matrix metalloproteinases (MMPs). To control MMP-mediated ECM breakdown, tissue inhibitors of metalloproteinases (TIMPs) are able to inhibit MMP activity. A disturbed balance of MMPs and TIMPs is found in various pathologic conditions, such as cancer, rheumatoid arthritis, and periodontitis. The role of MMPs in pathology has been extensively described in the literature. The main focus of this review lies in the biological functions of TIMPs and their occurrence in disease, especially in the head and neck area. Their biological functions and their role in diseases like oral cancers and periodontitis, and in the development of cleft palate, will be discussed. Finally, the diagnostic and therapeutical opportunities of TIMPs will be evaluated.

Macrophage migration inhibitory factor: a mediator of matrix metalloproteinase-2 production in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by destruction of bone and cartilage, which is mediated, in part, by synovial fibroblasts. Matrix metalloproteinases (MMPs) are a large family of proteolytic enzymes responsible for matrix degradation. Macrophage migration inhibitory factor (MIF) is a cytokine that induces the production of a large number of proinflammatory molecules and has an important role in the pathogenesis of RA by promoting inflammation and angiogenesis. In the present study, we determined the role of MIF in RA synovial fibroblast MMP production and the underlying signaling mechanisms. We found that MIF induces RA synovial fibroblast MMP-2 expression in a time-dependent and concentration-dependent manner. To elucidate the role of MIF in MMP-2 production, we produced zymosan-induced arthritis (ZIA) in MIF gene-deficient and wild-type mice. We found that MMP-2 protein levels were significantly decreased in MIF gene-deficient compared with wild-type mice joint homogenates. The expression of MMP-2 in ZIA was evaluated by immunohistochemistry (IHC). IHC revealed that MMP-2 is highly expressed in wild-type compared with MIF gene-deficient mice ZIA joints. Interestingly, synovial lining cells, endothelial cells, and sublining nonlymphoid mononuclear cells expressed MMP-2 in the ZIA synovium. Consistent with these results, in methylated BSA (mBSA) antigen-induced arthritis (AIA), a model of RA, enhanced MMP-2 expression was also observed in wild-type compared with MIF gene-deficient mice joints. To elucidate the signaling mechanisms in MIF-induced MMP-2 upregulation, RA synovial fibroblasts were stimulated with MIF in the presence of signaling inhibitors. We found that MIF-induced RA synovial fibroblast MMP-2 upregulation required the protein kinase C (PKC), c-jun N-terminal kinase (JNK), and Src signaling pathways. We studied the expression of MMP-2 in the presence of PKC isoform-specific inhibitors and found that the PKCdelta inhibitor rottlerin inhibits MIF-induced RA synovial fibroblast MMP-2 production. Consistent with these results, MIF induced phosphorylation of JNK, PKCdelta, and c-jun. These results indicate a potential novel role for MIF in tissue destruction in RA.

Matrix metalloproteinase-9 induces the formation of cartilage canals in the chondroepiphysis of the neonatal rabbit

BACKGROUND

An investigation of matrix metalloproteinase-9 (MMP-9) and its influence on vascular invasion in the secondary ossification center at the chondroepiphysis of developing long bones was undertaken. The effect of MMP-9 was compared with that of basic fibroblast growth factor (b-FGF), a potent angiogenic factor, and we assessed the chorioallantoic membrane (CAM) culture as a model for angiogenesis in osteochondral tissue.

METHODS

Seventy-two femoral and seventy-two humeral heads of thirty-six four-day postnatal rabbits were dissected immediately after each animal was killed. Solutions of MMP-9, b-FGF, and phosphate-buffered saline solution were applied, and the femoral and humeral chondroepiphyseal explants were incubated for ten days in CAM culture. This was used as an in vivo model to investigate the growth of blood vessels into the femoral and humeral heads of the neonatal rabbit. The explants were harvested from the CAM culture and analyzed histologically. A three-day incubation was also performed to look for early signs of vascular ingrowth into the cartilage matrix.

RESULTS

One hundred and twenty epiphyses from thirty rabbits were placed onto CAM culture successfully; of these, two were harvested at three days to assess early changes and 118 were harvested at ten days. Forty of the 118 cultures were still viable when harvested after ten days, giving a 33% yield. Both MMP-9 and b-FGF caused an increased vascular invasion into the chondroepiphysis. New blood vessels derived from the chorioallantoic membrane within cartilage canals were more numerous in MMP-9 treated epiphyses, and larger canals were more commonly seen when compared with a control group.

CONCLUSIONS

These findings confirmed that b-FGF is angiogenic at the chondroepiphysis. Matrix metalloproteinase-9 appears to be implicated in vascular invasion and induces the formation of new cartilage canals at the chondroepiphysis. The CAM culture model was a useful model for investigating angiogenesis in osteochondral tissue.

CLINICAL RELEVANCE

This study adds to the understanding of the complex biochemical interaction that occurs in cartilage when the advancing vasculature begins growing into the chondroepiphysis. A better knowledge of this angiogenic process will enable a better understanding of the pathological failure or disturbance of vasculogenesis, which results in dysplastic growth disorders and osteonecrosis.

Isoginkgetin inhibits tumor cell invasion by regulating phosphatidylinositol 3-kinase/Akt-dependent matrix metalloproteinase-9 expression

Matrix metalloproteinase (MMP)-9 plays a key role in tumor invasion. Inhibitors of MMP-9 were screened from Metasequoia glyptostroboides (Dawn redwood) and one potent inhibitor, isoginkgetin, a biflavonoid, was identified. Noncytotoxic levels of isoginkgetin decreased MMP-9 production profoundly, but up-regulated the level of tissue inhibitor of metalloproteinase (TIMP)-1, an inhibitor of MMP-9, in HT1080 human fibrosarcoma cells. The major mechanism of Ras-dependent MMP-9 production in HT1080 cells was phosphatidylinositol 3-kinase (PI3K)/Akt/nuclear factor-kappaB (NF-kappaB) activation. Expression of dominant-active H-Ras and p85 (a subunit of PI3K) increased MMP-9 activity, whereas dominant-negative forms of these molecules decreased the level of MMP-9. H-Ras did not increase MMP-9 in the presence of a PI3K inhibitor, LY294002, and a NF-kappaB inhibitor, SN50. Further studies showed that isoginkgetin regulated MMP-9 production via PI3K/Akt/NF-kappaB pathway, as evidenced by the findings that isoginkgetin inhibited activities of both Akt and NF-kappaB. PI3K/Akt is a well-known key pathway for cell invasion, and isoginkgetin inhibited HT1080 tumor cell invasion substantially. Isoginkgetin was also quite effective in inhibiting the activities of Akt and MMP-9 in MDA-MB-231 breast carcinomas and B16F10 melanoma. Moreover, isoginkgetin treatment resulted in marked decrease in invasion of these cells. In summary, PI3K/Akt is a major pathway for MMP-9 expression and isoginkgetin markedly decreased MMP-9 expression and invasion through inhibition of this pathway. This suggests that isoginkgetin could be a potential candidate as a therapeutic agent against tumor invasion.

Inflammation and cardiac remodeling during viral myocarditis

Acute viral myocarditis is the main cause of cardiac failure in young patients and accounts for up to 60% of "idiopathic" dilated cardiomyopathy. The clinical course of viral myocarditis is mostly insidious with limited cardiac inflammation and dysfunction. However, overwhelming inflammation may occur in a subset of patients, leading to fulminant cardiac injury, whereas others develop chronic heart failure due to autoimmune myocarditis. Today, little effective treatment exists for patients, apart from general supportive therapy and antifailure regimens. Urokinase-type plasminogen activator (u-PA) and matrix metalloproteinases (MMP) have been implicated in cardiac inflammation, matrix remodeling, and wound healing after cardiac injury. The present review will assess the mechanism by which these proteinases mediate cardiac dilatation, fibrosis, and dysfunction after cardiac stress or injury, in order to understand how inhibition of proteinases may provide a novel therapeutic tool to prevent cardiac dilatation and failure during viral myocarditis.

Mechanisms of irregular bleeding with hormone therapy: the role of matrix metalloproteinases and their tissue inhibitors

CONTEXT

Irregular bleeding is common in users of combined hormone therapy (HT) and often leads to invasive and expensive investigations to exclude underlying pathology. The mechanisms of HT-related bleeding are poorly understood. Endometrial matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are believed to regulate bleeding during the normal menstrual cycle and are known to be altered in breakthrough bleeding with progestogen-only contraception.

OBJECTIVE

The aim of this study was to determine how HT exposure alters endometrial production of MMP-1, -3, -9, and -14 and their tissue inhibitors TIMP-1, -2, -3, and -4 and to determine the relationship between MMP and TIMP production and bleeding patterns in HT users. Endometrial leukocytes regulating MMP production and activation were also assessed.

DESIGN

A prospective observational study was conducted between 2003 and 2005.

SETTING AND PATIENTS

The study occurred at a tertiary referral menopause clinic at King Edward Memorial Hospital, Western Australia, and included 25 postmenopausal women not taking HT and 73 women taking combined HT.

INTERVENTIONS

Endometrium was obtained during and outside bleeding episodes.

MAIN OUTCOME MEASURES

We assessed production of MMP-1, -3, -9, and -14 and their tissue inhibitors TIMP-1, -2, -3, and -4 and their relationship to bleeding patterns in HT users.

RESULTS

All MMPs studied, with the exception of MMP-9, were expressed at low levels in postmenopausal endometrium. Increases in both MMP-3 and -9 localization were seen in association with irregular bleeding, but these did not reach statistical significance. Endometrial production of TIMP-1 was significantly increased in association with bleeding. Endometrial leukocytes were not related to bleeding, with the exception of uterine natural killer cells, which were significantly increased during bleeding, as previously published.

CONCLUSIONS

Irregular bleeding in HT users is associated with a distinct pattern of MMP and TIMP production that differs from that seen in normal menstrual bleeding and from that seen in contraceptive-related breakthrough bleeding. This suggests that the endometrial balance between MMP and TIMP contributes to vascular breakdown with HT but by a different mechanism than that seen in normal menstruation or in breakthrough bleeding.

Tissue inhibitor of metalloproteinase-2 inhibits T-cell infiltration and preserves pancreatic β-cell function in an in vitro type 1 diabetes mellitus model

Type 1 diabetes mellitus (T1DM) results from autoreactive T-cells that attack and destroy insulin producing pancreatic beta-cells. This knowledge has provided a framework for numerous efforts to prevent or mitigate T1DM at various stages of the disease. In this study, we utilized an organ culture model of type 1 diabetes to determine whether tissue inhibitors of metalloproteinases (TIMPs) could block T-cell migration into the pancreas and ultimately preserve beta-cell function. We measured T-cell repertoires, insulin secretion, and performed immunohistochemistry and confocal laser microscopy in order to evaluate the effect of TIMP-1, TIMP-2, and TIMP-3 on our in vitro T1DM organ culture model. TIMP-2 decreased T-cell transmigration and preserved insulin production in our T1DM organ culture model. Moreover, TIMP-2 inhibited transmigration of diabetogenic T-cells across an islet microvascular endothelial cell layer. Our findings suggest that TIMP-2 is effective at blocking infiltration of autoreactive T-cells into target pancreas tissue thereby preserving pancreatic beta-cell mass.

High expression of tissue inhibitor of metalloproteinase-2 in serous ovarian carcinomas and the role of this expression in ovarian tumorigenesis

Tissue inhibitors of metalloproteinases (TIMPs) play key roles in maintaining homeostasis of the extracellular matrix by controlling matrix metalloproteinases (MMPs). In addition to their role in regulating MMPs, TIMPs have also been shown to have pluripotential effects on cell growth, apoptosis, and differentiation. The aim of this study was to evaluate TIMP-2 level in serous ovarian tumor tissues and to understand further the role of TIMP-2 protein in ovarian tumorigenesis. The expression of TIMP-2 was assessed by immunohistochemistry in a total of 57 ovarian specimens, including 5 normal ovaries, 12 benign serous cystadenomas, 20 serous borderline tumors, and 20 serous carcinomas. In addition, we transfected a TIMP-2 plasmid into the gynecologic cancer cell lines SKOV-3, 2774, and HeLa and then assayed cell growth, apoptosis, and MMP-2 activation. We found that TIMP-2 immunostaining was significantly more frequent in serous carcinomas, mainly in tumor epithelium, compared with cells of the other tissues studied. Tissue inhibitor of metalloproteinase-2 overexpression in ovarian cancer cells did not mediate proapoptosis, inhibited cisplatin-induced apoptosis, and induced MMP-2 expression. These findings suggest that TIMP-2 may function to favor tumor growth in serous ovarian tumorigenesis. Additional research is now needed to elucidate further the role of TIMP-2 in the biologic behavior of ovarian serous tumors.

Modulation of angiogenesis by tissue inhibitor of metalloproteinase-4

Despite the importance of MMP activity in the regulation of angiogenesis, relatively little is known about the role of TIMP-4, the most recently discovered endogenous MMP inhibitor, in modulating neovascularization. It has largely been assumed that all TIMPs are capable of inhibiting angiogenesis in vivo. However, it is now widely appreciated that TIMPs-1, -2, and -3 differ significantly in their ability to modulate angiogenic processes in vitro and angiogenesis in vivo. In order to study the effect of TIMP-4 in controlling angiogenesis, we have cloned and expressed TIMP-4 in a Pichia pastoris expression system, purified it to homogeneity, and tested its ability to regulate angiogenesis in vivo and in vitro. Our studies demonstrate that TIMP-4 is an inhibitor of capillary endothelial cell migration, but not of proliferation or of angiogenesis in vivo.

Localization and temporal regulation of tissue inhibitor of metalloproteinases-4 in mouse ovary

Tissue inhibitors of metalloproteinases (TIMPs) are potential regulators of tissue remodeling in the ovary. The aim of the present study was to examine the localization and temporal regulation of TIMP-4 protein in the mouse ovary. An induced superovulation model (eCG/hCG) was employed in immature mice to evaluate TIMP-4 protein expression profiles in ovaries collected during the follicular phase, the pre ovulatory period, and the luteal lifespan. Immunofluorescence results indicated that TIMP-4 protein was localized to theca of both antral and preovulatory follicles and adjacent ovarian stroma. After the initiation of luteinization with hCG, TIMP-4 was observed within the luteinizing granulosa cells and persisted throughout the lifespan of the corpus luteum. In the cycling ovary, TIMP-4 signaling localized to corpus luteum from previous estrous cycles, the theca of preovulatory follicles, and appeared to be lower in newly forming corpus luteum. Western analysis further showed that the levels of TIMP-4 increased significantly during the luteinization process of granulosa cells, but no significant change was found among all corpus luteum stages. A putative regulatory mechanism of TIMP-4 expression was identified utilizing an in vitro model. Treatment of cultured granulosa cells with hCG significantly augmented TIMP-4 protein expression levels. Together our data indicate that the luteinization process of granulosa cells is associated with up-regulation of TIMP-4 and that TIMP-4 might play an essential role in maintenance of the luteal function during the whole lifespan of corpus luteum.

Molecular regulation of tumor angiogenesis: mechanisms and therapeutic implications

Angiogenesis, the process of new capillary formation from a pre-existing vessel plays an essential role in both embryonic and postnatal development, in the remodeling of various organ systems, and in several pathologies, particularly cancer. In the last 20 years of angiogenesis research, a variety of angiogenic regulators, both positive and negative, have been identified. The discovery of several anti-angiogenic factors has led to the development of novel cancer therapies based on targeting a tumor's vascular supply. A number of these new therapies are currently being tested in clinical trials in the U.S.A. and elsewhere. A major advance in the field of anti-angiogenic therapy occurred recently when the FDA approved Avastin (bevacizumab), the first solely anti-angiogenesis therapy approved for treatment of human cancer. While it has long been appreciated that tumor growth and progression are dependent on angiogenesis, it is only recently that progress has been made in elucidating the molecular mechanisms that regulate the earliest stage in the angiogenic program, the angiogenic switch. This checkpoint is characterized by the transition of a dormant, avascular tumor into an active, vascular one. Anti-angiogenic therapies to date have essentially been designed to suppress the neovasculature in established tumors. However, identifying the mechanisms that cause a tumor to acquire an angiogenic phenotype may lead to the discovery of new therapeutic modalities and complementary diagnostics that could be used to block the angiogenic switch, thereby preventing subsequent tumor progression. In this chapter on the role of angiogenesis in cancer, we (1) provide an overview of the process of angiogenesis with special regard to the molecules and physiological conditions that regulate this process, (2) review recent studies describing the use of anti-angiogenic approaches in the treatment of a variety of human cancers, and (3) discuss the recent literature focused on the study of the molecules and molecular mechanisms that may be regulating the initiation of the angiogenic phenotype in tumors, and the clinical impact that this knowledge may have in the future.

Deficiencies in estrogen-mediated regulation of cerebrovascular homeostasis may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in menopausal and postmenopausal women

Despite the catastrophic consequence of ruptured intracranial aneurysms, very little is understood regarding their pathogenesis, and there are no reliable predictive markers for identifying at-risk individuals. Few studies have addressed the molecular pathological basis and mechanisms of intracranial aneurysm formation, growth, and rupture. The pathogenesis and rupture of cerebral aneurysms have been associated with inflammatory processes, and these have been implicated in the digestion and breakdown of vascular wall matrix. Epidemiological data indicate that the risk of cerebral aneurysm pathogenesis and rupture in women rises during and after menopause as compared to premenopausal women, and has been attributed to hormonal factors. Moreover, experimental evidence supports a role for estrogen in the modulation of each phase of the inflammatory response implicated in cerebral aneurysm pathogenesis and rupture. While the risk of aneurysm rupture in men also increases with age, this increased risk has been attributed to other recognized risk factors including cigarette smoking, use of alcohol, and history of hypertension, all of which are more common in men than women. We hypothesize, therefore, that decreases in both circulating estrogen levels and cerebrovascular estrogen receptor density may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in women during and after menopause. To test our hypothesis, experiments are needed to identify genes regulated by estrogen and to evaluate gene expression and intracellular mechanisms in cells/tissues exposed to varying concentrations and duration of treatment with estrogen, metabolites of estrogen, and selective estrogen receptor modulators (SERMs). Furthermore, it is not likely that the regulation of cerebrovascular homeostasis is due to the actions of estrogen alone, but rather the interplay of estrogen and other hormones and their associated receptor expression. The potential interactions of these hormones in the maintenance of normal cerebrovascular tone need to be elucidated. Additional studies are needed to define the role that estrogen and other sex hormones may play in the cerebrovascular circulation and the pathogenesis and rupture of cerebral aneurysms. Efforts directed at understanding the basic pathophysiological mechanisms of aneurysm pathogenesis and rupture promise to yield dividends that may have important therapeutic and clinical implications. The development of non-invasive tools such as molecular MRI for the detection of specific cells, molecular markers, and tissues may facilitate early diagnosis of initial pathophysiological changes that are undetectable by clinical examination or other diagnostic tools, and can also be used to evaluate the state of activity of cerebral aneurysm pathogenesis before, during, and after treatment.

Temporal and spatial expression of MMP-2,-9,-14 and their inhibitors TIMP-1,-2,-3 in the corpus luteum of the cycling rhesus monkey

The corpus luteum (CL) is a transient endocrine organ that secretes progesterone to support early pregnancy. If implantation is unsuccessful, luteolysis is initiated. Extensive tissue remodeling occurs during CL formation and luteolysis. In this study, we have studied the possible involvement of MMP-2, -9, -14, and their inhibitors, TIMP-1, -2, -3 in the CL of cycling rhesus monkey at various stages by in situ hybridization, immunohistochemistry and microscopic assessment. The results showed that the MMP-2 mRNA and protein were mainly expressed in the endothelial cells at the early and middle stages of the CL development, while their expressions were observed in the luteal cells at the late stage during luteal regression. MMP-9 protein was detected in the CL at the early and middle stages, and obviously increased at the late stage. The expressions of MMP-14 and TIMP-1 mRNA were high at the early and late stages, and low at the middle stage. TIMP-2 mRNA was high throughout all the stages, the highest level could be observed at the late stage. The TIMP-3 production was detected throughout all the stages, but obviously declined during CL regression. MMP-9, -14 and TIMP-1, -2, -3 were mainly localized in the cytoplasm of the steroidogenic cells. The results suggest that the MMP/TIMP system is involved in regulation of CL development in the primate, and the coordinated expression of MMP-2, -14 and TIMP-1, -3 may have a potential role in the CL formation and the functional maintaining, while the interaction of MMP-2, -9, -14 and TIMP-1, -2, -3 might also play a role in CL regression at the late stage of CL development in the primate.

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.

Systemic regulation of angiogenesis and matrix degradation in bone regeneration--distraction osteogenesis compared to rigid fracture healing

Aim of this study was the investigation of systemic biochemical regulation mechanisms of bone regeneration by angiogenic and matrix-degrading enzymes during distraction osteogenesis compared to rigid osteotomy bone healing. Serum samples of 10 otherwise healthy patients with callus distraction for lower limb-lengthening and 10 osteotomy patients undergoing elective axis correction have been collected prospectively in a standardized time schedule before and up to 6 months after the procedure. At the end of the individual investigation period, concentrations of metalloproteinases (MMP-9, -13), tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2) and the angiogenic factors angiogenin and VEGF have been detected by use of commercially available enzyme immunoassays. Results have been compared to our preliminary study on proMMP-1-3. In distraction osteogenesis, significantly elevated serum concentrations compared to baseline could be detected postoperatively for proMMP-1, MMP-9, TIMP-1, angiogenin and VEGF but not for proMMP-2, proMMP-3 or TIMP-2. In patients with rigid osteotomy healing, MMP-9, TIMP-1, TIMP-2, angiogenin and VEGF were significantly increased respectively. Comparison of both patient collectives revealed significantly higher increases of serum proMMP-1, VEGF and TIMP-1 in distraction patients during the lengthening period and significantly higher serum concentrations of TIMP-2 in late fracture healing period in osteotomy patients. Serum levels of MMP-13 were below the lowest standards, and therefore quantitative analysis was not possible. Bone regeneration in distraction osteogenesis and rigid osteotomy healing is accompanied by systemic increase of matrix-degrading and angiogenic factors in a certain time course and quantity. This might reflect biochemical regulation of local bone healing in the circulation. ProMMP-1, VEGF and TIMP-1 seem to be key regulatory factors during distraction osteogenesis.

Regulation of TIMP-2, MT1-MMP, and MMP-2 expression during C2C12 differentiation

Matrix metalloproteinases (MMPs) are zinc-dependent proteases capable of degrading extracellular matrix components. The activity of these proteases is tightly regulated through the actions of the tissue inhibitors of metalloproteinases (TIMPs). Although the regulation of MMPs and TIMPs during physiological and pathological remodeling has been investigated in a number of systems, almost nothing is known about their role in skeletal muscle differentiation. To investigate the role of MMP-mediated proteolysis during myogenesis, the regulation of TIMP-2, MT1-MMP, and MMP-2 expression was investigated during differentiation of the mouse myoblastic C2C12 cell line. We show that this trio is upregulated coincident with myogenesis. The more diffuse spatial distribution of TIMP-2 relative to MT1-MMP and MMP-2 suggests that TIMP-2 may exert MMP-independent functions during myogenesis. Elucidating the regulation of these molecules during muscle differentiation in vitro may lead to a better understanding of their role in pathological processes in muscle tissue in vivo.

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.

Expression of TIMP-1 and -2 in different growth patterns of adenoid cystic carcinoma

Tissue inhibitors of metalloproteinases (TIMPs) are special inhibitors of matrix metalloproteinases. To evaluate their roles in adenoid cystic carcinoma (ACC), we compared TIMP-1 and -2 mRNA and protein expression in different histological pattern of ACC. We obtained carcinoma cells from each of cribriform and tubular pattern of ACCs using by laser microdissection (LM), to determine the mRNAs expression of TIMP-1 and -2 using by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR), and to confirm expression of them by immunohistochemical staining. Our results showed that mRNA expression of TIMP-1 tended to be decreased in cribriform pattern compared with tubular pattern in four cases, and TIMP-1 significantly decreased in three cases. TIMP-2 also significantly decreased in cribriform than in tubular pattern in three of four cases. Protein expression of TIMP-1 and -2 decreased in the cribriform pattern compared to tubular pattern. These results indicate that there is close relationship between TIMPs and growth patterns of ACC, and TIMP-1 and -2 may play important roles in morphogenesis and biological character of adenoid cystic carcinoma.

TIMP-2: an endogenous inhibitor of angiogenesis

Remodeling of the extracellular matrix--regulated by the matrix metalloproteinases (MMPs) and their endogenous inhibitors--is an important component of disease progression in many chronic disease states. Unchecked MMP activity can result in significant tissue damage, facilitate disease progression and is associated with host responses to pathologic injury, such as angiogenesis. The tissue inhibitors of metalloproteinases (TIMPs) have been shown to regulate MMP activity. However, recent findings demonstrate that an MMP-independent effect of TIMP-2 inhibits the mitogenic response of human microvascular endothelial cells to growth factors. This is the first demonstration of a cell-surface signaling receptor for a member of the TIMP family and suggests that TIMP-2 functions to regulate cellular responses to growth factors. These new findings are integrated in a comprehensive model of TIMP-2 function in tissue homeostasis.