Tissue inhibitor of metalloproteinase (TIMP)-2 acts synergistically with synthetic matrix metalloproteinase (MMP) inhibitors but not with TIMP-4 to enhance the (Membrane type 1)-MMP-dependent activation of pro-MMP-2

Tissue Inhibitor of Metalloproteinases-2 (TIMP-2) as a Prognostic Biomarker in Acute Kidney Injury: A Narrative Review

Acute kidney damage (AKI) is a serious and common consequence among critically unwell individuals. Traditional biomarkers, such as serum creatinine, frequently fail to detect AKI in its early stages, necessitating the development of new accurate early biomarkers. Tissue inhibitor of metalloproteinases 2 (TIMP-2) has emerged as a promising biomarker for predicting early AKI. The present narrative review investigates the role of TIMP-2 in AKI prediction in a variety of clinical scenarios. In the NephroCheck® test, TIMP-2 exceeds established biomarkers for the early identification of AKI in terms of sensitivity and specificity when combined with insulin-like growth factor-binding protein 7 (IGFBP-7). Elevated levels of these biomarkers can provide a warning signal for AKI two to three days before clinical symptoms appear. TIMP-2 and IGFBP-7 have high predictive values, with an area under the curve (AUC) typically above 0.8, indicating good predictive capacity. For example, the [TIMP-2] × [IGFBP-7] product produced an AUC of 0.85 in surgical patients at high risk. In critically ill patients, a threshold of 0.3 (ng/mL)2/1000 demonstrated 92% sensitivity and 72% specificity. Elevated TIMP-2 levels have been correlated with higher mortality rates and the need for renal replacement therapy (RRT). In sepsis-associated AKI (SA-AKI), TIMP-2 levels combined with clinical prognostic models improved predictive accuracy (AUC: 0.822). Furthermore, elevated urine TIMP-2 levels were good predictors of AKI in pediatric patients after cardiac surgery, with AUC-ROC values of up to 0.848. Urine output and the presence of concomitant disorders may influence the prognostic accuracy of these biomarkers; therefore, more research is needed to fully understand their utility. The predictive value of TIMP-2 could be strengthened by combining it with other clinical parameters, reinforcing its role in the early detection and treatment of AKI.

Interleukin-1β activates matrix metalloproteinase-2 to alter lacrimal gland myoepithelial cell structure and function

The aim of the present study is to investigate the role of c-Jun N-terminal kinase (JNK) and matrix metalloproteinase-2 (MMP-2) in mediating the effects of interleukin-1β (IL-1β) on the function of lacrimal gland myoepithelial cells (MECs). MECs isolated from an α-smooth muscle actin-green fluorescent protein (SMA-GFP) transgenic mouse were treated with IL-1β alone or in the presence of SP600125, a JNK inhibitor, or ARP100, an MMP-2 inhibitor. The GFP intensity and the cell size/area were measured, and on day 7, the SMA, calponin, and pro-MMP-2 protein levels and the MEC contraction were assessed. At baseline, the control and treated cells showed no differences in GFP intensity or cell size. Starting on day 2 and continuing on days 4 and 7, the GFP intensity and cell size were significantly lower in the IL-1β-treated samples, and these effects were alleviated following inhibition of either JNK or MMP-2. Compared with the control, the levels of SMA and calponin were lower in the IL-1β-treated samples, and both the JNK and MMP-2 inhibitors reversed this trend. The pro-MMP-2 protein level was elevated in the IL-1β-treated samples, and this effect was abolished by the JNK inhibitor. Finally, oxytocin-induced MEC contraction was diminished in the IL-1β-treated samples, and both the JNK and MMP-2 inhibitors reversed this effect. Our data suggest that IL-1β uses the JNK/MMP-2 pathways to alter MEC functions, which might account for the diminished tears associated with aqueous-deficient dry eye disease.

Matrix metalloproteinases as biomarkers and therapeutic targets in colitis-associated cancer

Colorectal cancer (CRC) remains a major cause of morbidity and mortality. Therapeutic approaches for advanced CRC are limited and rarely provide long-term benefit. Enzymes comprising the 24-member matrix metalloproteinase (MMP) family of zinc- and calcium-dependent endopeptidases are key players in extracellular matrix degradation, a requirement for colon tumor expansion, invasion, and metastasis; hence, MMPs are an important research focus. Compared to sporadic CRC, less is known regarding the molecular mechanisms and the role of MMPs in the development and progression of colitis-associated cancer (CAC) - CRC on a background of chronic inflammatory bowel disease (IBD) - primarily ulcerative colitis and Crohn's disease. Hence, the potential of MMPs as biomarkers and therapeutic targets for CAC is uncertain. Our goal was to review data regarding the role of MMPs in the development and progression of CAC. We sought to identify promising prognostic and therapeutic opportunities and novel lines of investigation. A key observation is that since MMPs may be more active in early phases of CAC, using MMPs as biomarkers of advancing neoplasia and as potential therapeutic targets for adjuvant therapy in those with advanced stage primary CAC rather than overt metastases may yield more favorable outcomes.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

MMP8 increases tongue carcinoma cell-cell adhesion and diminishes migration via cleavage of anti-adhesive FXYD5

Matrix metalloproteinases (MMPs) modify bioactive factors via selective processing or degradation resulting in tumour-promoting or tumour-suppressive effects, such as those by MMP8 in various cancers. We mapped the substrates of MMP8 to elucidate its previously shown tumour-protective role in oral tongue squamous cell carcinoma (OTSCC). MMP8 overexpressing (+) HSC-3 cells, previously demonstrated to have reduced migration and invasion, showed enhanced cell-cell adhesion. By analysing the secretomes of MMP8 + and control cells with terminal amine isotopic labelling of substrates (TAILS) coupled with liquid chromatography and tandem mass spectrometry (LC-MS/MS), we identified 36 potential substrates of MMP8, including FXYD domain-containing ion transport regulator 5 (FXYD5). An anti-adhesive glycoprotein FXYD5 has been previously shown to predict poor survival in OTSCC. Cleavage of FXYD5 by MMP8 was confirmed using recombinant proteins. Furthermore, we detected a loss of FXYD5 levels on cell membrane of MMP8 + cells, which was rescued by inhibition of the proteolytic activity of MMP8. Silencing (si) FXYD5 increased the cell-cell adhesion of control but not that of MMP8 + cells. siFXYD5 diminished the viability and motility of HSC-3 cells independent of MMP8 and similar effects were seen in another tongue cancer cell line, SCC-25. FXYD5 is a novel substrate of MMP8 and reducing FXYD5 levels either with siRNA or cleavage by MMP8 increases cell adhesion leading to reduced motility. FXYD5 being a known prognostic factor in OTSCC, our findings strengthen its potential as a therapeutic target.

TIMP-2 regulates proliferation, invasion and STAT3-mediated cancer stem cell-dependent chemoresistance in ovarian cancer cells

BACKGROUND

The metzincin family of metalloproteinases and the tissue inhibitors of metalloproteinases (TIMPs) are essential proteins required for biological processes during cancer progression. This study aimed to determine the role of TIMP-2 in ovarian cancer progression and chemoresistance by reducing TIMP-2 expression in vitro in Fallopian tube secretory epithelial (FT282) and ovarian cancer (JHOS2 and OVCAR4) cell lines.

METHODS

FT282, JHOS2 and OVCAR4 cells were transiently transfected with either single or pooled TIMP-2 siRNAs. The expression of different genes after TIMP-2 knock down (T2-KD) or in response to chemotherapy was determined at the mRNA level by quantitative real time PCR (qRT-PCR) and at the protein level by immunofluorescence. Sensitivity of the cell lines in response to chemotherapy after TIMP-2 knock down was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-Ethynyl-2'-deoxyuridine (EdU) assays. Cell invasion in response to TIMP-2 knockdown was determined by xCELLigence.

RESULTS

Sixty to 90 % knock down of TIMP-2 expression was confirmed in FT282, OVCAR4 and JHOS2 cell lines at the mRNA and protein levels. TIMP-2 knock down did not change the mRNA expression of TIMP-1 or TIMP-3. However, a significant downregulation of MMP-2 in T2-KD cells occurred at both the protein and activation levels, compared to Control (Cont; scrambled siRNA) and Parental cells (P, transfection reagent only). In contrast, membrane bound MT1-MMP protein levels were significantly upregulated in T2-KD compared to Cont and P cells. T2-KD cells exhibited enhanced proliferation and increased sensitivity to cisplatin and paclitaxel treatments. Enhanced invasion was observed in the T2-KD-JOSH2 and OVCAR4 cells but not in T2-KD-FT282 cells. Treatment with cisplatin or paclitaxel significantly elevated the expression of TIMP-2 in Cont cells but not in T2-KD cells, consistent with significantly elevated expression of chemoresistance and CSC markers and activation of STAT3. Furthermore, a potent inhibitor of STAT3 activation, Momelotinib, suppressed chemotherapy-induced activation of P-STAT3 in OVCAR4 cells with concomitant reductions in the expression of chemoresistance genes and CSC markers.

CONCLUSIONS

The above results suggest that TIMP-2 may have a novel role in ovarian cancer proliferation, invasion and chemoresistance.

XCL1-XCR1 pathway promotes trophoblast invasion at maternal-fetal interface by inducing MMP-2/MMP-9 activity

PROBLEM

Certain chemokines with their receptors can promote or inhibit trophoblast cell migration and invasion in human first-trimester placenta. Whether the lymphotactin (Lptn; XCL1)-XC chemokine receptor 1 (XCR1) chemokine pathway affects trophoblast cell migration and invasion in human first-trimester placenta remains unclear.

METHOD OF STUDY

The expression pattern of chemokine XCL1 and its receptor XCR1 was detected in human first-trimester by qRT-PCR, and the effect of recombinant human XCL1 (rhXCL1) on trophoblast cell function was tested by wound healing and Transwell assays. Matrix metalloproteinase (MMP) activity in trophoblast cells treated with rhXCL1 was assessed via qRT-PCR and gelatin zymography.

RESULTS

Abundant XCR1 mRNA was expressed in the first-trimester decidua and villi. XCL1 and XCR1 mRNA were expressed at a higher level in the first-trimester than in the term placenta. RhXCL1 promoted trophoblast cell migration and invasion by increasing MMP-9 and MMP-2 activity and that of the MMP-2/tissue inhibitor of metalloproteinases 2 (TIMP-2) complex via the phosphatidylinositol 3-kinase (PI3K)/AKT kinase (AKT), mitogen-activated protein kinase (MEK), and JUN N-terminal kinase (JNK) signaling pathways.

CONCLUSION

XCL1-XCR1 chemokine pathway promotes trophoblast invasion by increasing matrix metalloproteinase activity in human first-trimester placenta.

Matrix Metalloproteinase Inhibitors as Investigational and Therapeutic Tools in Unrestrained Tissue Remodeling and Pathological Disorders

Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic enzymes that degrade various proteins in the extracellular matrix (ECM). MMPs may also regulate the activity of membrane receptors and postreceptor signaling mechanisms and thereby affect cell function. The MMP family includes collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs, and other MMPs. Inactive proMMPs are cleaved by other MMPs or proteases into active MMPs, which interact with various protein substrates in ECM and cell surface. MMPs regulate important biological processes such as vascular remodeling and angiogenesis and may be involved in the pathogenesis of cardiovascular disorders such as hypertension, atherosclerosis, and aneurysm. The role of MMPs is often assessed by measuring their mRNA expression, protein levels, and proteolytic activity using gel zymography. MMP inhibitors are also used to assess the role of MMPs in different biological processes and pathological conditions. MMP activity is regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP balance could determine the net MMP activity, ECM turnover, and tissue remodeling. Also, several synthetic MMP inhibitors have been developed. Synthetic MMP inhibitors include a large number of zinc-binding globulins (ZBGs), in addition to non-ZBGs and mechanism-based inhibitors. MMP inhibitors have been proposed as potential tools in the management of osteoarthritis, cancer, and cardiovascular disorders. However, most MMP inhibitors have broad-spectrum actions on multiple MMPs and could cause undesirable musculoskeletal side effects. Currently, doxycycline is the only MMP inhibitor approved by the Food and Drug Administration. New generation biological and synthetic MMP inhibitors may show greater MMP specificity and fewer side effects and could be useful in targeting specific MMPs, reducing unrestrained tissue remodeling, and the management of MMP-related pathological disorders.

Selective small-molecule inhibitors as chemical tools to define the roles of matrix metalloproteinases in disease

The focus of this article is to highlight novel inhibitors and current examples where the use of selective small-molecule inhibitors has been critical in defining the roles of matrix metalloproteinases (MMPs) in disease. Selective small-molecule inhibitors are surgical chemical tools that can inhibit the targeted enzyme; they are the method of choice to ascertain the roles of MMPs and complement studies with knockout animals. This strategy can identify targets for therapeutic development as exemplified by the use of selective small-molecule MMP inhibitors in diabetic wound healing, spinal cord injury, stroke, traumatic brain injury, cancer metastasis, and viral infection. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

Temozolomide does not influence the transcription or activity of matrix metalloproteinases 9 and 2 in glioma cell lines

Glioblastoma multiforme (GBM) is a treatment-resistant malignancy with poor prognosis. Temozolomide (TMZ) is widely used as a first-line drug for GBM. Although this improves patient prognosis, it does not completely eradicate the tumour. Even after total surgical resection, GBM can exhibit uncontrollable invasiveness at the tumour margins owing to activation of matrix metalloproteinases (MMPs) such as MMP-2 and -9; these degrade collagen IV in the basement membrane, which normally prevents cancer invasion. TMZ induces DNA damage and activates transcription factors including c-jun, c-fos, nuclear factor-κβ, and early growth response protein-1, which have putative binding sites on the MMP-9 promoter. TMZ may therefore enhance tumour invasion by stimulating MMP-9 transcription and enzymatic activity. To test this hypothesis, we investigated MMP-2 and -9 mRNA transcription and activity in GBM cell lines treated with TMZ. Human A172 GBM cells were exposed to TMZ (25% and 50% inhibitory concentrations) for 24 or 48h; cell cycle distribution and mRNA levels of MMP-2 and -9 were evaluated using flow cytometry and semi-quantitative reverse transcription PCR, respectively. MMP-2 and -9 enzymatic activities were assessed using gelatin zymography in human A172 and U373 MG GBM cells exposed to TMZ under the same conditions. TMZ altered A172 cell cycle distribution, but not MMP-2 or -9 mRNA levels. TMZ did not affect MMP-2 or -9 enzymatic activities in A172 or U373 MG cells. These findings indicated that TMZ is therefore unlikely to promote GBM invasiveness.

Expression and Activity of Metalloproteinases in Depression

BACKGROUND Depression is one of the most common mental disorders and often co-exists with somatic diseases. The most probable cause of comorbidity is a generalized inflammatory process that occurs in both depression and somatic diseases. Matrix metalloproteinases MMPs play a role in modulating inflammation and their impact in many inflammatory diseases has been investigated. The purpose of this study was to evaluate gene expression for selected polymorphisms of MMP-2 (C-735T), MMP-7 (A-181G), and MMP-9 (T-1702A, C1562T), which have been confirmed to participate in development of depression, and TIMP-2 (G-418C, tissue inhibitor of MMP). Activity variability of pro-MMP-2 and pro-MMP-9 was measured in a group of people with depression and a group of healthy individuals. MATERIAL AND METHODS The examined population comprised 142 individuals suffering from depression and 100 individuals who formed a control group (CG). Designations were carried out for MMP-2 (C-735T), MMP-7 (A-181G), MMP-9 (T-1702A, C1562T), and TIMP-2 (G-418C). RESULTS For all examined and tested MMPs and for TIMP-2, gene expression at the mRNA level was higher in patients with depression than in the CG. Similar results were recorded for gene expression at the protein level, while expression on the protein level for TIMP-2 was higher in the CG. Change in activity of MMP-2 and pro-MMP-2 was statistically more significant in the group with depression. The opposite result was recorded for MMP-9 and pro-MMP-9, in which the change in activity was statistically more significant in the CG. CONCLUSIONS Changes in MMPs and TIMP expression may be a common element in, or perhaps even a marker for, recurrent depressive disorders and somatic diseases.

Lipid-soluble ginseng extract inhibits invasion and metastasis of B16F10 melanoma cells

This study was performed to elucidate the effect of a lipid-soluble ginseng extract (LSGE) on cancer invasion and metastasis. The LSGE, even at noncytotoxic concentrations, potently inhibited invasion and migration of B16F10 mouse melanoma cells in a dose-dependent manner. In the presence of 3 μg/mL of LSGE, the invasion and migration of B16F10 cells were significantly inhibited by 98.1% and 71.4%, respectively. Furthermore, the LSGE decreased mRNA and protein levels of matrix metalloproteinase (MMP)-2 in B16F10 cells, leading to a decrease in MMP-2 activity. After B16F10 cells were intravenously injected in the tail vein of C57BL/6 mice, 1000 mg/kg/day of LSGE was orally administered for 13 days, after which lung metastasis of cancer cells was inhibited by 59.3%. These findings indicate that LSGE inhibits cancer cell invasion and migration in vitro and lung metastasis of melanoma cells in vivo by inhibiting MMP-2 expression.

Low-dose UVB irradiation prevents MMP2-induced skin hyperplasia by inhibiting inflammation and ROS

Skin cancer is one of the most common types of malignancy in the world. UV radiation is known as the primary environmental carcinogen responsible for skin cancer development. However, UV radiation is a ubiquitous substance existing in the environment and the physiological effect of UV radiation is consistently ignored. Therefore, in the present study, the physiological effect of UV radiation on inhibition of skin cancer was investigated. Normal mouse skin was processing by no pre-radiation or pre-radiation of low-dose UV before a medium or high dose of UV radiation. We found that the low-dose pre-radiated mouse skin tissue exhibited low skin inflammation, skin ROS production and consequently low skin epithelial hyperplasia after the medium-dose UV radiation compared with the no pre-radiated mouse. However, this inhibition was not indicated in the high-dose UV radiation group after low-dose pre-radiation. Furthermore, western blot analysis and gelatin zymography showed low expression and activation of MMP2 in the skin tissues processed following medium-dose radiation, but not in tissues treated with high-dose radiation after a low-dose pre-radiation. Further investigation of MMP2 inhibitors of TIMP2/TIMP4 showed an upregulated TIMP2 expression, but not TIMP4. Collectively, these data indicate that low-dose pre-radiation attenuates the skin inflammation and ROS production induced by medium-dose UV radiation and also elevates TIMP2 to withstand MMP2, therefore suppressing skin hyperplasia. The present study indicates a novel concept or prophylactic function of moderate UV radiation as a preventative strategy.

VEGF secreted by hypoxic Müller cells induces MMP-2 expression and activity in endothelial cells to promote retinal neovascularization in proliferative diabetic retinopathy

In proliferative diabetic retinopathy (PDR), retinal ischemia promotes neovascularization (NV), which can lead to profound vision loss in diabetic patients. Treatment for PDR, panretinal photocoagulation, is inherently destructive and has significant visual consequences. Therapies targeting vascular endothelial growth factor (VEGF) have transformed the treatment of diabetic eye disease but have proven inadequate for treating NV, prompting exploration for additional therapeutic options for PDR patients. In this regard, extracellular proteolysis is an early and sustained activity strictly required for NV. Extracellular proteolysis in NV is facilitated by the dysregulated activity of matrix metalloproteinases (MMPs). Here, we set out to better understand the regulation of MMPs by ischemia in PDR. We demonstrate that accumulation of hypoxia-inducible factor-1α in Müller cells induces the expression of VEGF, which, in turn, promotes increased MMP-2 expression and activity in neighboring endothelial cells (ECs). MMP-2 expression was detected in ECs in retinal NV tissue from PDR patients, whereas MMP-2 protein levels were elevated in the aqueous of PDR patients compared with controls. Our findings demonstrate a complex interplay among hypoxic Müller cells, secreted angiogenic factors, and neighboring ECs in the regulation of MMP-2 in retinal NV and identify MMP-2 as a target for the treatment of PDR.

Selective inhibition of matrix metalloproteinase-9 attenuates secondary damage resulting from severe traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and long-term disability. Following the initial insult, severe TBI progresses to a secondary injury phase associated with biochemical and cellular changes. The secondary injury is thought to be responsible for the development of many of the neurological deficits observed after TBI and also provides a window of opportunity for therapeutic intervention. Matrix metalloproteinase-9 (MMP-9 or gelatinase B) expression is elevated in neurological diseases and its activation is an important factor in detrimental outcomes including excitotoxicity, mitochondrial dysfunction and apoptosis, and increases in inflammatory responses and astrogliosis. In this study, we used an experimental mouse model of TBI to examine the role of MMP-9 and the therapeutic potential of SB-3CT, a mechanism-based gelatinase selective inhibitor, in ameliorating the secondary injury. We observed that activation of MMP-9 occurred within one day following TBI, and remained elevated for 7 days after the initial insult. SB-3CT effectively attenuated MMP-9 activity, reduced brain lesion volumes and prevented neuronal loss and dendritic degeneration. Pharmacokinetic studies revealed that SB-3CT and its active metabolite, p-OH SB-3CT, were rapidly absorbed and distributed to the brain. Moreover, SB-3CT treatment mitigated microglial activation and astrogliosis after TBI. Importantly, SB-3CT treatment improved long-term neurobehavioral outcomes, including sensorimotor function, and hippocampus-associated spatial learning and memory. These results demonstrate that MMP-9 is a key target for therapy to attenuate secondary injury cascades and that this class of mechanism-based gelatinase inhibitor–with such desirable pharmacokinetic properties–holds considerable promise as a potential pharmacological treatment of TBI.

Mathematical modeling of cancer invasion: the role of membrane-bound matrix metalloproteinases

One of the hallmarks of cancer growth and metastatic spread is the process of local invasion of the surrounding tissue. Cancer cells achieve protease-dependent invasion by the secretion of enzymes involved in proteolysis. These overly expressed proteolytic enzymes then proceed to degrade the host tissue allowing the cancer cells to disseminate throughout the microenvironment by active migration and interaction with components of the extracellular matrix (ECM) such as collagen. In this paper we develop a mathematical model of cancer invasion which consider the role of matrix metalloproteinases (MMPs). Specifically our model will focus on two distinct types of MMP, i.e., soluble, diffusible MMPs (e.g., MMP-2) and membrane-bound MMPs (e.g., MT1-MMP), and the roles each of these plays in cancer invasion. The implications of MMP-2 activation by MMP-14 and the tissue inhibitor of metalloproteinases-2 are considered alongside the effect the architecture of the matrix may have when applied to a model of cancer invasion. Elements of the ECM architecture investigated include pore size of the matrix, since in some highly dense collagen structures such as breast tissue, the cancer cells are unable to physically fit through a porous region, and the crosslinking of collagen fibers. In this scenario, cancer cells rely on membrane-bound MMPs to forge a path through which degradation by other MMPs and movement of cancer cells becomes possible.

Microfabricated collagen tracks facilitate single cell metastatic invasion in 3D

While the mechanisms employed by metastatic cancer cells to migrate remain poorly understood, it has been widely accepted that metastatic cancer cells can invade the tumor stroma by degrading the extracellular matrix (ECM) with matrix metalloproteinases (MMPs). Although MMP inhibitors showed early promise in preventing metastasis in animal models, they have largely failed clinically. Recently, studies have shown that some cancer cells can use proteolysis to mechanically rearrange their ECM to form tube-like "microtracks" which other cells can follow without using MMPs themselves. We speculate that this mode of migration in the secondary cells may be one example of migration which can occur without endogenous protease activity in the secondary cells. Here we present a technique to study this migration in a 3D, collagen-based environment which mimics the size and topography of the tracks produced by proteolytically active cancer cells. Using time-lapse phase-contrast microscopy, we find that these microtracks permit the rapid and persistent migration of noninvasive MCF10A mammary epithelial cells, which are unable to otherwise migrate in 3D collagen. Additionally, while highly metastatic MDAMB231 breast cancer cells are able to invade a 3D collagen matrix, seeding within the patterned microtracks induced significantly increased cell migration speed, which was not decreased by pharmacological MMP inhibition. Together, these data suggest that microtracks within a 3D ECM may facilitate the migration of cells in an MMP-independent fashion, and may reveal novel insight into the clinical challenges facing MMP inhibitors.

The matrix metalloproteinase inhibitor marimastat promotes neural progenitor cell differentiation into neurons by gelatinase-independent TIMP-2-dependent mechanisms

Metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs), produced in the brain by cells of non-neural and neural origin, including neural progenitors (NPs), are emerging as regulators of nervous system development and adult brain functions. In the present study, we explored whether MMP-2, MMP-9, and TIMP-2, abundantly produced in the brain, modulate NP developmental properties. We found that treatment of NPs, isolated from the murine fetal cerebral cortex or adult subventricular zone, with the clinically tested broad-spectrum MMP inhibitor Marimastat profoundly affected the NP differentiation fate. Marimastat treatment allowed for an enrichment of our cultures in neuronal cells, inducing NPs to generate higher percentage of neurons and a lower percentage of astrocytes, possibly affecting NP commitment. Consistently with its proneurogenic effect, Marimastat early downregulated the expression of Notch target genes, such as Hes1 and Hes5. MMP-2 and MMP-9 profiling on proliferating and differentiating NPs revealed that MMP-9 was not expressed under these conditions, whereas MMP-2 increased in the medium as pro-MMP-2 (72 kDa) during differentiation; its active form (62 kDa) was not detectable by gel zymography. MMP-2 silencing or administration of recombinant active MMP-2 demonstrated that MMP-2 does not affect NP neuronal differentiation, nor it is involved in the Marimastat proneurogenic effect. We also found that TIMP-2 is expressed in NPs and increases during late differentiation, mainly as a consequence of astrocyte generation. Endogenous TIMP-2 did not modulate NP neurogenic potential; however, the proneurogenic action of Marimastat was mediated by TIMP-2, as demonstrated by silencing experiments. In conclusion, our data exclude a major involvement of MMP-2 and MMP-9 in the regulation of basal NP differentiation, but highlight the ability of TIMP-2 to act as key effector of the proneurogenic response to an inducing stimulus such as Marimastat.

Control and inhibition analysis of complex formation processes

Background

Proteolytic degradation of the extracellular matrix (ECM) is a key event in tumour metastasis and invasion. Matrix metalloproteinases (MMPs) are a family of endopeptidases that degrade most of the components of the ECM. Several broad-spectrum MMP inhibitors (MMPIs) have been developed, but have had little success due to side effects. Thus, it is important to develop mathematical methods to provide new drug treatment strategies. Matrix metalloproteinase 2 (MMP2) activation occurs via a mechanism involving complex formation that consists of membrane type 1 MMP (MT1-MMP), tissue inhibitor of matrix metalloproteinase 2 (TIMP2) and MMP2. Here, we focus on developing a method for analysing the complex formation process.

Results

We used control analysis to investigate inhibitor responses in complex formation processes. The essence of the analysis is to define the response coefficient which measures the inhibitory efficiency, a small fractional change of concentration of a targeting molecule in response to a small fractional change of concentration of an inhibitor. First, by using the response coefficient, we investigated models for general classes of complex formation processes: chain reaction systems composed of ordered steps, and chain reaction systems and site-binding reaction systems composed of unordered multi-branched steps. By analysing the ordered step models, we showed that parameter-independent inequalities between the response coefficients held. For the unordered multi-branched step models, we showed that independence of the response coefficients with respect to equilibrium constants held. As an application of our analysis, we discuss a mathematical model for the MMP2 activation process. By putting the experimentally derived parameter values into the model, we were able to conclude that the TIMP2 and MMP2 interaction is the most efficient interaction to consider in selecting inhibitors.

Conclusions

Our result identifies a new drug target in the process of the MMP2 activation. Thus, our analysis will provide new insight into the design of more efficient drug strategies for cancer treatment.

Filamin A controls matrix metalloproteinase activity and regulates cell invasion in human fibrosarcoma cells

Filamins are an important family of actin-binding proteins that, in addition to bundling actin filaments, link cell surface adhesion proteins, signaling receptors and channels to the actin cytoskeleton, and serve as scaffolds for an array of intracellular signaling proteins. Filamins are known to regulate the actin cytoskeleton, act as mechanosensors that modulate tissue responses to matrix density, control cell motility and inhibit activation of integrin adhesion receptors. In this study, we extend the repertoire of filamin activities to include control of extracellular matrix (ECM) degradation. We show that knockdown of filamin increases matrix metalloproteinase (MMP) activity and induces MMP2 activation, enhancing the ability of cells to remodel the ECM and increasing their invasive potential, without significantly altering two-dimensional random cell migration. We further show that within filamin A, the actin-binding domain is necessary, but not sufficient, to suppress the ECM degradation seen in filamin-A-knockdown cells and that dimerization and integrin binding are not required. Filamin mutations are associated with neuronal migration disorders and a range of congenital malformations characterized by skeletal dysplasia and various combinations of cardiac, craniofacial and intestinal anomalies. Furthermore, in breast cancers loss of filamin A has been correlated with increased metastatic potential. Our data suggest that effects on ECM remodeling and cell invasion should be considered when attempting to provide cellular explanations for the physiological and pathological effects of altered filamin expression or filamin mutations.

Assessment of gelatinases (MMP-2 and MMP-9) by gelatin zymography

Gelatin zymography is a simple yet powerful method to detect proteolytic enzymes capable of degrading gelatin from various biological sources. It is particularly useful for the assessment of two key members of the matrix metalloproteinase family, MMP-2 (gelatinase A) and MMP-9 (gelatinase B), due to their potent gelatin-degrading activity. This polyacrylamide gel electrophoresis-based method can provide a reliable assessment of the type of gelatinase, relative amount, and activation status (latent, compared with active enzyme forms) in cultured cells, tissues, and biological fluids. The method can be used to investigate factors that regulate gelatinase expression and modulate zymogen activation in experimental systems. The system provides information on the pattern of gelatinase expression and activation in human cancer tissues and how this relates to cancer progression. Interpretation of the data obtained in gelatin zymography requires a thorough understanding of the principles and pitfalls of the technique; this is particularly important when evaluating enzyme levels and the presence of active gelatinase species. If properly used, gelatin zymography is an excellent tool for the study of gelatinases in biological systems.

Matrix metalloproteinase inhibitors as investigative tools in the pathogenesis and management of vascular disease

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade various components of the extracellular matrix (ECM). MMPs could also regulate the activity of several non-ECM bioactive substrates and consequently affect different cellular functions. Members of the MMPs family include collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs, and others. Pro-MMPs are cleaved into active MMPs, which in turn act on various substrates in the ECM and on the cell surface. MMPs play an important role in the regulation of numerous physiological processes including vascular remodeling and angiogenesis. MMPs may also be involved in vascular diseases such as hypertension, atherosclerosis, aortic aneurysm, and varicose veins. MMPs also play a role in the hemodynamic and vascular changes associated with pregnancy and preeclampsia. The role of MMPs is commonly assessed by measuring their gene expression, protein amount, and proteolytic activity using gel zymography. Because there are no specific activators of MMPs, MMP inhibitors are often used to investigate the role of MMPs in different physiologic processes and in the pathogenesis of specific diseases. MMP inhibitors include endogenous tissue inhibitors (TIMPs) and pharmacological inhibitors such as zinc chelators, doxycycline, and marimastat. MMP inhibitors have been evaluated as diagnostic and therapeutic tools in cancer, autoimmune disease, and cardiovascular disease. Although several MMP inhibitors have been synthesized and tested both experimentally and clinically, only one MMP inhibitor, i.e., doxycycline, is currently approved by the Food and Drug Administration. This is mainly due to the undesirable side effects of MMP inhibitors especially on the musculoskeletal system. While most experimental and clinical trials of MMP inhibitors have not demonstrated significant benefits, some trials still showed promising results. With the advent of new genetic and pharmacological tools, disease-specific MMP inhibitors with fewer undesirable effects are being developed and could be useful in the management of vascular disease.

Reduced NO signaling during pregnancy attenuates outward uterine artery remodeling by altering MMP expression and collagen and elastin deposition

Recent findings indicate that endothelial nitric oxide (NO) plays a key role in uterine artery outward circumferential remodeling during pregnancy. Although the underlying mechanisms are not known, they likely involve matrix metalloproteinases (MMPs). The goal of this study was to examine the linkage among NO inhibition, expansive remodeling, and MMP expression within the uterine vascular wall. Adult female rats were treated with N(G)-nitro-L-arginine methyl ester [L-NAME (LPLN)] beginning on day 10 of pregnancy and until death at day 20 and compared with age-matched controls [late pregnant (LP)]. Mean arterial pressure of LPLN rats was significantly higher than controls. LPLN fetal and placental weights were significantly reduced compared with controls. Main uterine arteries (mUA) were collected to determine dimensional properties (lumen area and wall thickness), collagen and elastin content, and levels of endothelial nitric oxide synthase (eNOS) and MMP expression. Circumferential remodeling was attenuated, as evidenced by significantly smaller lumen diameters. eNOS RNA and protein were significantly (>90%) decreased in the LPLN mUA compared with LP. Collagen and elastin contents were significantly increased in LPLN rats by ∼10 and 25%, respectively, compared with LP (P < 0.05). Both MMP-2 and tissue inhibitors of metalloproteinase-2 as assessed by immunofluorescence were lower in the endothelium (reduction of 60%) and adventitia (reduction of 50%) of LPLN compared with LP mUA. Membrane bound MMP-1 (MT1-MMP) as assessed by immunoblot was significantly decreased in LPLN. These data suggest a novel contribution of MMPs to gestational uterine vascular remodeling and substantiate the linkage between NO signaling and gestational remodeling of the uterine circulation via altered MMP, TIMP-2, and MT1-MMP expression and activity.

Looking at the proteases from a simple perspective

Proteases have received enormous interest from the research and medical communities because of their significant roles in several human diseases. Some examples include the involvement of thrombin in thrombosis, HIV-1 protease in Acquired Immune Deficiency Syndrome, cruzain in Trypanosoma cruzi infection, and membrane-type 1 matrix metalloproteinase in tumor invasion and metastasis. Many efforts has been undertaken to design effective inhibitors featuring potent inhibitory activity, specificity, and metabolic stability to those proteases involved in such pathologies. Protease inhibitors usually target the active site, but some of them act by other inhibitory mechanisms. The understanding of the structure-function relationships of proteases and inhibitors has an impact on new inhibitor drugs designing. In this paper, the structures of four proteases (thrombin, HIV-protease, cruzain, and a matrix metalloproteinase) are briefly reviewed, and used as examples of the importance of proteases for the development of new treatment strategies, leading to a longer and healthier life.

Role of matrix metalloproteinases and therapeutic benefits of their inhibition in spinal cord injury

This review will focus on matrix metalloproteinases (MMPs) and their inhibitors in the context of spinal cord injury (SCI). MMPs have a specific cellular and temporal pattern of expression in the injured spinal cord. Here we consider their diverse functions in the acutely injured cord and during wound healing. Excessive activity of MMPs, and in particular gelatinase B (MMP-9), in the acutely injured cord contributes to disruption of the blood-spinal cord barrier, and the influx of leukocytes into the injured cord, as well as apoptosis. MMP-9 and MMP-2 regulate inflammation and neuropathic pain after peripheral nerve injury and may contribute to SCI-induced pain. Early pharmacologic inhibition of MMPs or the gelatinases (MMP-2 and MMP-9) results in an improvement in long-term neurological recovery and is associated with reduced glial scarring and neuropathic pain. During wound healing, gelatinase A (MMP-2) plays a critical role in limiting the formation of an inhibitory glial scar, and mice that are genetically deficient in this protease showed impaired recovery. Together, these findings illustrate complex, temporally distinct roles of MMPs in SCIs. As early gelatinase activity is detrimental, there is an emerging interest in developing gelatinase-targeted therapeutics that would be specifically tailored to the acute injured spinal cord. Thus, we focus this review on the development of selective gelatinase inhibitors.

Sulfonate-containing thiiranes as selective gelatinase inhibitors

Matrix metalloproteinases (MMPs) are important zinc-dependent endopeptidases. Two members of this family of enzymes called gelatinases (MMP-2 and MMP-9) have been implicated in a number of human diseases, including cancer, neurological and cardiovascular diseases, and inflammation, to name a few. We describe in this report the preparation and evaluation of two structural types of thiirane inhibitors that show selectivity toward gelatinases. The biphenyl series targets both gelatinases, whereas the monophenyl analogues exhibit potent inhibition of only MMP-2. The latter structural type also exhibits improved water solubility and metabolic stability, both traits desirable for progress of these molecules forward in gelatinase-dependent animal models of disease.

Immunohistochemical evaluation of MMP-2 and TIMP-2 in canine mammary tumours: a survival study

Canine mammary tumours (CMTs) are a very heterogeneous group of neoplasms with variable prognosis. Their aggressiveness is mainly due to their ability to invade locally and to metastasize. The degradation of extracellular matrix components is an important determinant of the invasive phenotype. The aims of this study were to analyse by immunohistochemistry and double immunofluorescence the expression of metalloproteinase 2 (MMP-2) and tissue inhibitor of metalloproteinase 2 (TIMP-2) in eight normal canine mammary glands and 118 CMTs (24 benign, 94 malignant) and to investigate relationships with metastatic disease and survival. MMP-2 and TIMP-2 expression was higher in malignant tumours than in normal canine mammary tissue and benign tumours. The main difference between benign and malignant CMTs was the pattern of expression of both molecules: benign tumours presented TIMP-2 and MMP-2 immunoreactivity in the myoepithelial cells lining the basement membrane of tubuloalveolar structures, while malignant tumours showed mainly diffuse expression in neoplastic cells. In malignant tumours, increased TIMP-2 expression was significantly associated with the development of distant metastases, lower overall survival and lower disease-free survival. MMP-2 expression was not significantly associated to any of these parameters. These results suggest that the immunohistochemical expression of TIMP-2 is a useful prognostic factor in CMTs.

Roles of matrix metalloproteinases in cancer progression and their pharmacological targeting

Matrix metalloproteinases (MMPs) consist of a multigene family of zinc-dependent extracellular matrix (ECM) remodeling endopeptidases implicated in pathological processes, such as carcinogenesis. In this regard, their activity plays a pivotal role in tumor growth and the multistep processes of invasion and metastasis, including proteolytic degradation of ECM, alteration of the cell-cell and cell-ECM interactions, migration and angiogenesis. The underlying premise of the current minireview is that MMPs are able to proteolytically process substrates in the extracellular milieu and, in so doing, promote tumor progression. However, certain members of the MMP family exert contradicting roles at different stages during cancer progression, depending among other factors on the tumor stage, tumor site, enzyme localization and substrate profile. MMPs are therefore amenable to therapeutic intervention by synthetic and natural inhibitors, providing perspectives for future studies. Multiple therapeutic agents, called matrix metalloproteinase inhibitors (MMPIs) have been developed to target MMPs, attempting to control their enzymatic activity. Even though clinical trials with these compounds do not show the expected results in most cases, the field of MMPIs is ongoing. This minireview critically evaluates the role of MMPs in relation to cancer progression, and highlights the challenges, as well as future prospects, for the design, development and efficacy of MMPIs.

Endogenous matrix metalloproteinases 2 and 9 regulate activation of CD4+ and CD8+ T cells

We reported that inhibiting matrix metalloproteinases (MMP), known to remodel the extracellular matrix, also down-regulated antigen-specific T-cell responses. However, the direct role of MMP2 and MMP9 in regulating intracellular function in T cells is unknown. Markers of cellular activation and cytokine profiles were examined in anti-CD3-stimulated wild-type C57BL/6 mouse-derived CD4(+) or CD8(+) T cells, or MMP2- or MMP9-deficient (-/-) mice. MMP-sufficient T cells were also treated with SB-3CT, a highly selective inhibitor of MMP2 and MMP9. The effect of MMP-specific inhibition on T cell-dependent, antigen-specific murine lung injury was examined in vivo. SB-3CT induced dose-dependent reductions in anti-CD3-stimulated T-cell proliferation. Although MMP2(-/-) cells were reduced 20%, anti-CD3-induced proliferation was down-regulated 80-85% in MMP9(-/-) or in SB-3CT-treated wild-type CD4(+) and CD8(+) T cells. Intracellular calcium flux was augmented in response to MMP inhibition or deficiency in the same cells, and IL-2 production was reduced in CD4(+) and CD8(+) MMP9(-/-) T cells. SB-3CT-mediated MMP2 and MMP9 inhibition abrogated antigen-specific CD8(+) T cell-mediated lung injury in vivo. MMPs, particularly MMP9, may function intracellularly to regulate T-cell activation. T cell-targeted MMP inhibition may provide a novel approach of immune regulation in the treatment of T cell-mediated diseases.

Coordinate action of membrane-type matrix metalloproteinase-1 (MT1-MMP) and MMP-2 enhances pericellular proteolysis and invasion

Membrane-type matrix metalloproteinase-1 (MT1-MMP) mediates cleavage of not only MMP-2/gelatinase A for activation, but also a variety of substrates including type I collagen (reviewed in Cancer Sci 2005; 96: 212-7). MMP-2 activation involves tissue inhibitor of MMP (TIMP)-2 as a bridging molecule between MT1-MMP and pro-MMP-2. Thus, net activity of MT1-MMP and MMP-2 is regulated in a complex manner depending on TIMP-2 concentration. During invasive growth of tumor cells in type I collagen matrix, MT1-MMP initiates denaturation of collagen into gelatin, which is subsequently digested further by MMP-2 adjacent to MT1-MMP. Coordinate action of MT1-MMP and MMP-2 may facilitate pericellular proteolysis, and enhance not only tumor invasion/migration but also cell growth. Tetraspanins as binding proteins of MT1-MMP regulate MT1-MMP subcellular localization and compartmentalization, leading to efficient MMP-2 activation and proteolysis coupled with cellular function.

Protective role of betulinic acid on TNF-alpha-induced cell adhesion molecules in vascular endothelial cells

Vascular inflammation is an important event in the development of vascular diseases such as tumor progression and atherosclerosis. In the present study, betulinic acid (BA) treatment was found to show potent inhibitory effect on vascular inflammation process by TNF-alpha in human umbilical vein endothelial cells (HUVEC). Pretreatment of HUVEC with BA was blocked TNF-alpha induced expression level of cell adhesion molecules such as intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), endothelial cell selectin (E-selectin) as well as gelatinase in TNF-alpha-activated HUVEC in a dose-dependent manner. When preincubated with BA, the adhesion of HL-60 cells to TNF-alpha-induced HUVEC was significantly decreased in a concentration-dependent manner. TNF-alpha-induced intracellular ROS was markedly decreased by pretreatment with BA. Furthermore, BA significantly inhibited the translocation and transcriptional activity of NF-kappaB increased by TNF-alpha. In conclusion, these results suggested a vascular protective role of BA via inhibition of ROS and NF-kappaB activation in HUVEC.

Non-apoptotic Fas signaling regulates invasiveness of glioma cells and modulates MMP-2 activity via NFkappaB-TIMP-2 pathway

Fas (CD95/APO-1) is a cell surface "death receptor" that mediates apoptosis upon engagement by its ligand, FasL. Paradoxically, Fas/FasL can also promote cell invasion among non-apoptotic cells; here, we show that Fas/FasL signaling can promote tumor invasion when apoptosis is compromised. We have developed a recombinant FasL Interfering Protein (FIP) to interfere with Fas signaling in C6 glioma cells expressing both Fas receptor and its ligand. FIP administration did not affect cell viability but impaired cell motility and invasiveness of glioma cells. Blockade of Fas signaling reduced MMP-2 activity in glioma cells, that was associated with down-regulation of MAPK signaling, and AP-1 and NFkappaB-driven transcription. FIP treatment did not affect mmp-2 and mt1-mmp expression but significantly attenuated timp-2 expression and TIMP-2 amount in the culture medium. Studies with pharmacological inhibitors of JNK/c-Jun (SP600125) and NFkappaB (BAY11-7082) signaling pathways demonstrated that timp-2 expression is regulated by NFkappaB transcription factor. Our findings show that non-apoptotic Fas signaling activated in the autocrine manner or through microenvironment derived factors can regulate invasiveness of glioma cells via modulation of MMP-2 activation, likely by controlling TIMP-2 expression.

To bind zinc or not to bind zinc: an examination of innovative approaches to improved metalloproteinase inhibition

This short review highlights some recent advances in matrix metalloproteinase inhibitor (MMPi) design and development. Three distinct approaches to improved MMP inhibition are discussed: (1) the identification and investigation of novel zinc-binding groups (ZBGs), (2) the study of non-zinc-binding MMPi, and (3) mechanism-based MMPi that form covalent adducts with the protein. Each of these strategies is discussed and their respective advantages and remaining challenges are highlighted. The studies discussed here bode well for the development of ever more selective, potent, and well-tolerated MMPi for treating several important disease pathologies.

The inactive 44-kDa processed form of membrane type 1 matrix metalloproteinase (MT1-MMP) enhances proteolytic activity via regulation of endocytosis of active MT1-MMP

Membrane type 1 (MT1) matrix metalloproteinase (MMP-14) is a membrane-tethered MMP considered to be a major mediator of pericellular proteolysis. MT1-MMP is regulated by a complex array of mechanisms, including processing and endocytosis that determine the pool of active proteases on the plasma membrane. Autocatalytic processing of active MT1-MMP generates an inactive membrane-tethered 44-kDa product (44-MT1) lacking the catalytic domain. This form preserves all other enzyme domains and is retained at the cell surface. Paradoxically, accumulation of the 44-kDa form has been associated with increased enzymatic activity. Here we report that expression of a recombinant 44-MT1 (Gly(285)-Val(582)) in HT1080 fibrosarcoma cells results in enhanced pro-MMP-2 activation, proliferation within a three-dimensional collagen I matrix, and tumor growth and lung metastasis in mice. Stimulation of pro-MMP-2 activation and growth in collagen I was also observed in other cell systems. Expression of 44-MT1 in HT1080 cells is associated with a delay in the rate of active MT1-MMP endocytosis resulting in higher levels of active enzyme at the cell surface. Consistently, deletion of the cytosolic domain obliterates the stimulatory effects of 44-MT1 on MT1-MMP activity. In contrast, deletion of the hinge turns the 44-MT1 form into a negative regulator of enzyme function in vitro and in vivo, suggesting a key role for the hinge region in the functional relationship between active and processed MT1-MMP. Together, these results suggest a novel role for the 44-kDa form of MT1-MMP generated during autocatalytic processing in maintaining the pool of active enzyme at the cell surface.

Activation-coupled membrane-type 1 matrix metalloproteinase membrane trafficking

The transmembrane collagenase MT1-MMP (membrane-type 1 matrix metalloproteinase), also known as MMP-14, has a critical function both in normal development and in cancer progression, and is subject to extensive controls at the post-translational level which affect proteinase activity. As zymogen activation is crucial for MT1-MMP activity, an alpha1-PI (alpha1-proteinase inhibitor)-based inhibitor was designed by incorporating the MT1-MMP propeptide cleavage sequence into the alpha1-PI reactive-site loop (designated alpha1-PI(MT1)) and this was compared with wild-type alpha1-PI (alpha1-PI(WT)) and the furin inhibitory mutant alpha1-PI(PDX). Alpha1-PI(MT1) formed an SDS-stable complex with furin and inhibited proMT1-MMP activation. A consequence of the loss of MT1-MMP activity was the activation of proMMP-2 and the inhibition of MT1-MMP-mediated collagen invasion. alpha1-PI(MT1) expression also resulted in the intracellular accumulation of a glycosylated species of proMT1-MMP that was retained in the perinuclear region, leading to significantly decreased cell-surface accumulation of proMT1-MMP. These observations suggest that both the subcellular localization and the activity of MT1-MMP are regulated in a coordinated fashion, such that proMT1-MMP is retained intracellularly until activation of its zymogen, then proMT1-MMP traffics to the cell surface in order to cleave extracellular substrates.

Metabolism of a highly selective gelatinase inhibitor generates active metabolite

(4-Phenoxyphenylsulfonyl)methylthiirane (inhibitor 1) is a highly selective inhibitor of gelatinases (matrix metalloproteinases 2 and 9), which is showing considerable promise in animal models for cancer and stroke. Despite demonstrated potent, selective, and effective inhibition of gelatinases both in vitro and in vivo, the compound is rapidly metabolized, implying that the likely activity in vivo is due to a metabolite rather than the compound itself. To this end, metabolism of inhibitor 1 was investigated in in vitro systems. Four metabolites were identified by LC/MS-MS and the structures of three of them were further validated by comparison with authentic synthetic samples. One metabolite, 4-(4-thiiranylmethanesulfonylphenoxy)phenol (compound 21), was generated by hydroxylation of the terminal phenyl group of 1. This compound was investigated in kinetics of inhibition of several matrix metalloproteinases. This metabolite was a more potent slow-binding inhibitor of gelatinases (matrix metalloproteinase-2 and matrix metalloproteinase-9) than the parent compound 1, but it also served as a slow-binding inhibitor of matrix metalloproteinase-14, the upstream activator of matrix metalloproteinase-2.

Control of matrix metalloproteinase catalytic activity

As their name implies, MMPs were first described as proteases that degrade extracellular matrix proteins, such as collagens, elastin, proteoglycans, and laminins. However, studies of MMP function in vivo have revealed that these proteinases act on a variety of extracellular protein substrates, often to activate latent forms of effector proteins, such as antimicrobial peptides and cytokines, or to alter protein function, such as shedding of cell-surface proteins. Because their substrates are diverse, MMPs are involved in variety of homeostatic functions, such as bone remodeling, wound healing, and several aspects of immunity. However, MMPs are also involved in a number of pathological processes, such as tumor progression, fibrosis, chronic inflammation, tissue destruction, and more. A key step in regulating MMP proteolysis is the conversion of the zymogen into an active proteinase. Several proMMPs are activated in the secretion pathway by furin proprotein convertases, but for most the activation mechanisms are largely not known. In this review, we discuss both authentic and potential mechanisms of proMMP activation.

Neutrophil Elastase Up-Regulates Cathepsin B and Matrix Metalloprotease-2 Expression

Neutrophil elastase (NE) activity is increased in many diseases. Other families of proteases, including cathepsins and matrix metalloproteases (MMPs), are also present at elevated levels in similar disease conditions. We postulated that NE could induce expression of cathepsins and MMPs in human macrophages. NE exposure resulted in macrophages, producing significantly greater amounts of cathepsin B and latent and active MMP-2. Cathepsin B and MMP-2 activities were decreased in Pseudomonas-infected NE knockout mice compared with wild-type littermates. We also demonstrate that NE can activate NF-kappaB in macrophages, and inhibition of NF-kappaB resulted in a reduction of NE-induced cathepsin B and MMP-2. Also, inhibition of TLR-4 or transfection of macrophages with dominant-negative IL-1R-associated kinase-1 resulted in a reduction of NE-induced cathepsin B and MMP-2. This study describes for the first time a novel hierarchy among proteases whereby a serine protease up-regulates expression of MMPs and cathepsins. This has important implications for therapeutic intervention in protease-mediated diseases.

Metastasis-related factors expressed in pT1 pN0 breast cancer: Assessment of recurrence risk

OBJECTIVES

Previous reports have indicated that small breast cancers without lymph node metastasis present a favorable prognosis. However, 10-20% of patients with T1 N0 invasive ductal carcinoma experience recurrence and have a poor prognosis. The objective of this study was to examine whether certain metastasis-related factors are prognostic of cancer recurrence in such patients at risk for relapse.

METHODS

Nineteen patients with the carcinoma who had recurrence 1-15 years after margin-free resection were examined. The control group consisted of 20 patients with pT1 pN0 invasive ductal carcinoma who had no recurrence for > or =10 years after radical surgery. The two groups were compared with respect to clinical profiles, conventional neoplastic features, and immunohistochemical expressions of 16 metastasis-related factors.

RESULTS

No significant difference was found between the two groups in clinical profiles and conventional neoplastic features. However, six factors (MMP-2, MT1-MMP, T1MP-2, VEGF, cMET, and PCNA) were significantly expressed in the recurrence group against the control group. MMP-9 was significantly less expressed in the recurrence group. Of these factors, MMP-2, MT1-MMP, and VEGF showed the highest adjusted odds ratios.

CONCLUSION

MMP family and growth factors may be promising predictors of recurrence risk of early stage breast cancer.

The effects of tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and transforming growth factor-beta1 on pulp fibroblast mediated collagen degradation

Dental pulp destruction is believed to be regulated, in part, by the matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs). Cytokines are believed to be important in the pathogenesis of pulpitis. This study examined the effects that TNF-alpha, IL-1beta, IL-6, and TGF-beta1 have on the collagen degradation mediated by pulp fibroblasts utilizing a cell-mediated collagen degradation assay. Reverse transcriptase-polymerase chain reaction, Western blot analyses, and zymography were utilized to examine multiple MMPs and TIMPs. The collagen degradation mediated by these cells was stimulated by these cytokines. TNF-alpha, IL-1beta, and IL-6 increased the mRNA and/or protein expression of MMP-1, MMP-2, and MMP-3. TGF-beta1 decreased MMP-1 mRNA expression, while only slightly affecting the MMP-2 and MMP-3 mRNA and/or protein. These cytokines did not affect the expression of TIMP-1 or TIMP-2. These results suggest that these cytokines affect pulp destruction, in part, by differentially regulating the MMPs and TIMPs.

Randomized, double-blind, placebo-controlled trial of marimastat in glioblastoma multiforme patients following surgery and irradiation

PURPOSE

Because raised matrix metalloprotease (MMP) levels are associated with glioma invasion and angiogenesis, we tested the efficacy of marimastat (MT) an orally active drug that can reduce MMP levels, in patients with gliomas.

PATIENTS AND METHODS

A total of 162 patients with intracranial glioblastoma multiforme or gliosarcomas who had undergone surgery and radiotherapy participated in this multicenter, double-blind, placebo-controlled, parallel group study conducted at 20 institutions. Seventy-nine patients (57 male, 22 female, median age 58 years) were randomized to receive placebo (PB), and 83 patients (51 male, 32 female, median age 57 years) were randomized to receive MT, 10 mg orally twice daily, until tumor progression.

RESULTS

This intention-to-treat efficacy analysis showed no statistically significant difference between MT and PB groups with respect to survival (P = 0.38, log rank test). The median survival time from protocol initiation was 37.9 weeks for the PB group and 42.9 weeks for the MT group, with a hazard ratio of 1.16 (95% CI 0.83 to 1.60). There were no statistically significant differences in quality of life between the PB and MT groups, as assessed by the FACT-BR questionnaire. Musculoskeletal toxicities led to dose modification or withdrawal in 20% of MT-treated and 1.2% of PB-treated patients.

CONCLUSION

MT does not improve survival in patients with glioblastoma or gliosarcoma following surgery and radiotherapy. Therefore, single-agent MT appears unwarranted; however, MT in combination with cytotoxic chemotherapy may be warranted, as suggested by observations in our study and other studies.

Vascular endothelial growth factor-regulated ovarian cancer invasion and migration involves expression and activation of matrix metalloproteinases

Vascular endothelial growth factor (VEGF) expression is elevated in primary ovarian tumors and metastases. We examined the effect of VEGF on epithelial ovarian cancer (EOC) in vitro invasion and migration and underlying mechanisms. Using the Matrigel invasion assay and colloidal gold phagokinetic track assay, we found that VEGF induced EOC DOV13 invasion and migration in a matrix metalloproteinase (MMP)-dependent manner. Using Western blotting, we show that VEGF, at 20-80 ng/ml, induced secretion of pro-MMP-7 and pro-MMP-9 and activation of pro-MMP-2 in DOV13 conditioned medium in a concentration-dependent manner. However, gelatinolytic activity and total MMP-7 protein in DOV13 conditioned medium reached the maximum upon VEGF treatment at 20-40 ng/ml and decreased at higher-concentration VEGF treatment (80 ng/ml), as shown by DQ-gelatin degradation assay and ELISA. In addition to the effect on MMP secretion/activation, VEGF stimulated secretion of TIMP-2; and blocking TIMP-2 activity by an anti-TIMP-2 MAb significantly increased VEGF (80 ng/ml)-induced DOV13 invasion (p < 0.05), suggesting that VEGF may regulate MMP-2 activity in DOV13 conditioned medium through TIMP-2. Using real-time PCR, we found that VEGF, at 20 ng/ml, significantly increased the expression of VEGFR-1 and VEGFR-2 by approximately 4-fold and 31-fold, respectively, compared to untreated control (p < 0.05). However, the inducing effect of VEGF on VEGFR-2 expression and the internal expression of VEGF121 in DOV13 cells decreased with increasing of VEGF concentration, suggesting the existence of a negative feedback regulatory mechanism. In summary, our results indicate that VEGF may regulate EOC invasion and migration through VEGFR-mediated secretion and activation of MMPs.

Matrix metalloproteinase inhibitor RECK expression in canine tumors

Matrix metalloproteinases (MMPs) selectively degrade the extracellular matrix, and they have been reported to play an important role in tumor invasion, metastasis and angiogenesis. These enzymes are closely related to tumor malignancy and patient survival time. Recently, reversion-inducing cysteine-rich protein with Kazal motifs (RECK) gene was identified as an endogenous membrane-anchored MMP inhibitor. The down-regulation of RECK has been implicated in tumor progression. In this study, the expression levels of the RECK messenger ribonucleic acid (mRNA) in various spontaneously developed canine tumors were investigated by using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), and the correlation between RECK and clinicopathological factors, as well as MMP-9 expression were analyzed. The median age of 36 dogs investigated in this study was 9 years old (range, 1-15 years old). Quantitative RT-PCR could detect low levels of expression of RECK mRNA in the tumor samples. The expression levels of RECK mRNA in some tumor tissue samples were significantly lower than those in normal tissue samples. No significant associations of RECK with clinicopathological factors were observed. Using the Mann-Whitney U test, the expression level of the MMP-9 mRNA was observed to be significantly correlated to RECK expression (p<0.05).

Inhibitory effect of DA-125, a new anthracyclin analog antitumor agent, on the invasion of human fibrosarcoma cells by down-regulating the matrix metalloproteinases

Matrix metalloproteinases (MMPs), zinc-dependent proteolytic enzymes, play a pivotal role in tumor metastasis by cleavage of extracellular matrix as well as non-matrix substrates. In this study, we examined the influence of DA-125, a new anthracyclin analog, on the gene expression of MMPs (MMP-2, MMP-9 and MT1-MMP), tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) and in vitro invasiveness of human fibrosarcoma cells. Dose-dependent decreases of MMPs and TIMPs mRNA levels were observed in DA-125-treated HT1080 human fibrosarcoma cells detected by reverse transcriptase-polymerase chain reaction. Gelatin zymography analysis also showed a significant down-regulation of MMP-2 and MMP-9 expression in HT1080 cells treated with DA-125 compared to controls. In addition, DA-125 inhibited the invasion, motility and cell migration, and colony formation of tumor cells. These data, therefore, provide direct evidence for the role of DA-125 as a potential cancer chemotherapeutic agent, which can markedly inhibit the invasive capacity of malignant cells. Further, to clarify the transcriptional regulatory pathway, we primarily investigated the role of nuclear factor-kappaB (NF-kappaB) in the expression of MMPs by DA-125 in HT1080 cells. Electrophoretic mobility shift assay demonstrated that DA-125 modulates the binding activity of NF-kappaB. Using the luciferase reporter gene assay, a dose-dependent down-regulation of NF-kappaB-mediated luciferase expression was also observed. These results suggest that DA-125 down-regulates MMPs expression in HT1080 cells through the NF-kappaB-mediated pathway.

The transmembrane domain is essential for the microtubular trafficking of membrane type-1 matrix metalloproteinase (MT1-MMP)

Membrane type-1 matrix metalloproteinase (MT1-MMP) degrades the extracellular matrix, initiates the activation pathway of soluble MMPs and regulates the functionality of cell adhesion signaling receptors, thus playing an important role in many cell functions. Intracellular transport mechanisms, currently incompletely understood, regulate the presentation of MT1-MMP at the cell surface. We have focused our efforts on identifying these mechanisms. To understand the transport of MT1-MMP across the cell, we used substitution and deletion mutants, the trafficking of which was examined using antibody uptake and Chariot delivery experiments. Our experiments have demonstrated that the microtubulin cytoskeleton and the centrosomes (the microtubulin cytoskeleton-organizing centers) are essential for the trafficking and the internalization of MT1-MMP. We determined that after reaching the plasma membrane, MT1-MMP is internalized in the Rab-4-positive recycling endosomes and the Rab-11-positive pericentrosomal recycling endosomes. The microtubular trafficking causes the protease to accumulate in the pericentrosomal region of the cell. We believe that the presence of the transmembrane domain is required for the microtubular vesicular trafficking of MT1-MMP because the soluble mutants are not presented at the cell surface and they are not delivered to the centrosomes. The observed transport mechanisms provide a vehicle for the intracellular targets and, accordingly, for an intracellular cleavage function of MT1-MMP in malignant cells, which routinely overexpress this protease.