Extracellular regulation of metalloproteinases

Tissue inhibitor of matrix metalloproteinase-3 has both anti-metastatic and anti-tumourigenic properties

TIMP-3 is one of four tissue inhibitors of matrix metalloproteinases, the endogenous inhibitors of the matrix metalloproteinase enzymes. These enzymes have an important role in metastasis, in the invasion of cancer cells through the basement membrane and extracellular matrix. TIMP-1, -2 and -4 both promote and inhibit tumour development, in a context-dependent manner, however TIMP-3 is consistently anti-tumourigenic. TIMP-3 is also the only insoluble member of the family, being either bound to the extracellular matrix or the low density lipoprotein-related protein-1, through which it can be endocytosed. Levels of TIMP-3 have also been shown to be regulated by micro RNAs and promoter hypermethylation, resulting in frequent silencing in many tumour types, to the extent that its expression has been suggested as a prognostic marker in some tumours, being associated with lower levels of metastasis, or better response to treatment. TIMP-3 has been shown to have anti-metastatic effects, both through inhibition of matrix metalloproteinases and ADAM family members and downregulation of angiogenesis. This occurs via interactions with receptors including VEGF, via modulation of signaling pathways and due to protease inhibition. TIMP-3 has also been shown to reduce tumour growth rate, most often by inducing apoptosis by stabilisation of death receptors. A number of successful mechanisms of delivery of TIMP-3 to tumour or inflammatory sites have been investigated in vitro or in animal studies. It may therefore be worthwhile further exploring the use of TIMP-3 as a potential anti-metastatic or anti-tumorigenic therapy for many tumour types.

ColXV Aggravates Adipocyte Apoptosis by Facilitating Abnormal Extracellular Matrix Remodeling in Mice

The extracellular matrix (ECM) is a highly dynamic structural network and plays an essential role in cell behavior and regulation during metabolic homeostasis and obesity progression. Abnormal ECM remodeling impairs adipocyte plasticity required for diverse cellular functions. Collagen XV (ColXV) is a proteoglycan localized to the outermost layer of basement membranes (BMs) and forms a bridge between the BMs and the fibrillar collagen matrix. Nevertheless, how ColXV affects ECM composition and the reason for subsequent adipocyte apoptosis is still unclear. This report found, through RNA-seq data, that ColXV is linked to cell growth and ECM remodeling. Findings show that, in response to excessive expression of extracellular ColXV, the AMPK/mTORC1 pathway is strongly activated and triggers a cascade of mitochondrial apoptosis. This is the first study to make use of ECM three-dimensional reconstruction, based on decellularization in the adipose tissues and the study reveals that ColXV is an activation factor that alters ECM remodeling in adipose tissues. It was also demonstrated that the fibroblast growth factor 2 (FGF2)/fibroblast growth factor receptor 1 (FGFR1) axis involved in ECM remodeling is suppressed by ColXV due to reduction of FGF2 translocation to FGFR1. Furthermore, ColXV induced remodeling of ECM preceding apoptosis and continued to induce apoptosis in adipocytes. Collectively, our findings establish ColXV as a basement membrane collagen with homology to ColXVIII, indicating that it is one of the positive regulators for inducing ECM remodeling and further promoting adipocyte apoptosis.

Roles of circRNAs in the tumour microenvironment

The tumour microenvironment (TME) constitutes the area surrounding the tumour during its development and has been demonstrated to play roles in cancer-related diseases through crosstalk with tumour cells. Circular RNAs (circRNAs) are a subpopulation of endogenous noncoding RNAs (ncRNAs) that are ubiquitously expressed in eukaryotes and have multiple biological functions in the regulation of cancer onset and progression. An increasing number of studies have shown that circRNAs participate in the multifaceted biological regulation of the TME. However, details on the mechanisms involved have remained elusive until now. In this review, we analyse the effects of circRNAs on the TME from various perspectives, including immune surveillance, angiogenesis, hypoxia, matrix remodelling, exo-circRNAs and chemoradiation resistance. Currently, the enormous potential for circRNA use in targeted therapy and as noninvasive biomarkers have drawn our attention. We emphasize the prospect of targeting circRNAs as an essential strategy to regulate TME, overcome cancer resistance and improve therapeutic outcomes.

The Diverse Roles of TIMP-3: Insights into Degenerative Diseases of the Senescent Retina and Brain

Tissue inhibitor of metalloproteinase-3 (TIMP-3) is a component of the extracellular environment, where it mediates diverse processes including matrix regulation/turnover, inflammation and angiogenesis. Rare TIMP-3 risk alleles and mutations are directly linked with retinopathies such as age-related macular degeneration (AMD) and Sorsby fundus dystrophy, and potentially, through indirect mechanisms, with Alzheimer's disease. Insights into TIMP-3 activities may be gleaned from studying Sorsby-linked mutations. However, recent findings do not fully support the prevailing hypothesis that a gain of function through the dimerisation of mutated TIMP-3 is responsible for retinopathy. Findings from Alzheimer's patients suggest a hitherto poorly studied relationship between TIMP-3 and the Alzheimer's-linked amyloid-beta (A) proteins that warrant further scrutiny. This may also have implications for understanding AMD as aged/diseased retinae contain high levels of A. Findings from TIMP-3 knockout and mutant knock-in mice have not led to new treatments, particularly as the latter does not satisfactorily recapitulate the Sorsby phenotype. However, recent advances in stem cell and in vitro approaches offer novel insights into understanding TIMP-3 pathology in the retina-brain axis, which has so far not been collectively examined. We propose that TIMP-3 activities could extend beyond its hitherto supposed functions to cause age-related changes and disease in these organs.

Tamoxifen-induced alterations in the expression of selected matrix metalloproteinases (MMP-2, -9, -10, and -13) and their tissue inhibitors (TIMP-2 and -3) in the chicken ovary

Matrix metalloproteinases (MMPs) are a family of peptidases that disintegrate extracellular matrix (ECM) molecules associated with tissue remodeling, including reproductive tissues. Their actions are largely controlled by specific tissue inhibitors of MMPs (TIMPs). The role and regulation of MMPs in the chicken ovary is largely unknown. The aim of the present study was to examine the effect of tamoxifen (TMX; estrogen receptor modulator) treatment on the expression of selected members of the MMP system in the laying hen ovary. The activity of MMP-2 and -9 was also examined. Real-time polymerase chain reaction and western blot analyses revealed changes in mRNA and/or protein expression of MMP-2, -9, -10, -13, TIMP-2, and TIMP-3 in the following ovarian follicles after TMX treatment: white (WF), yellowish (YF), small yellow (SYF), and the largest yellow preovulatory (F3-F1). The response to TMX depended on the stage of follicle development and the layer of follicular wall. Moreover, ovarian regression following TMX treatment was accompanied by both an increase in total activity of MMP-2 in the theca layer of F3-F2 and granulosa layer of F2, and a decrease in total activity of MMP-2 in the WF, YF, and SYF, and MMP-9 in theca of F3-F1. In conclusion, the TMX-induced changes in MMP-2, -9, -10, and -13, and TIMP-2 and -3 mRNA expression, as well as MMP-2 and -9 activity, were dependent on tissue and the stage of follicular maturation. Our findings strongly suggests a role for estrogen in regulating the transcription, translation, and/or posttranslational activity of members of the MMP system. Further, these components may be involved in the orchestration of ECM turnover and cellular functions during ovary regression, which occur under conditions of reduced estrogenic activity.

Matrix-degrading protease ADAMTS-5 cleaves inter-α-inhibitor and releases active heavy chain 2 in synovial fluids from arthritic patients

Destruction of the cartilage matrix in joints is an important feature of arthritis. Proteolytic degradation of cartilage glycoproteins can contribute to the loss of matrix integrity. Human inter-α-inhibitor (IαI), which stabilizes the extracellular matrix, is composed of the light-chain serine proteinase inhibitor bikunin and two homologous heavy chains (HC1 and HC2) covalently linked through chondroitin 4-sulfate. Inflammation promotes the transfer of HCs from chondroitin 4-sulfate to hyaluronan by tumor necrosis factor-stimulated gene-6 protein (TSG-6). This reaction generates a covalent complex between the heavy chains and hyaluronan that can promote leukocyte invasion. This study demonstrates that both IαI and the HC-hyaluronan complex are substrates for the extracellular matrix proteases ADAMTS-5 and matrix metalloprotease (MMP) -3, -7, and -13. The major cleavage sites for all four proteases are found in the C terminus of HC2. ADAMTS-5 and MMP-7 displayed the highest activity toward HC2. ADAMTS-5 degradation products were identified in mass spectrometric analysis of 29 of 33 arthropathic patients, indicating that ADAMTS-5 cleavage occurs in synovial fluid in arthritis. After cleavage, free HC2, together with TSG-6, is able to catalyze the transfer of heavy chains to hyaluronan. The release of extracellular matrix bound HC2 is likely to increase the mobility of the HC2/TSG-6 catalytic unit and consequently increase the rate of the HC transfer reaction. Ultimately, ADAMTS-5 cleavage of HC2 could alter the physiological and mechanical properties of the extracellular matrix and contribute to the progression of arthritis.

Evaluation of metalloproteinases-2, -9, and -13 post photobiomodulation in mice talocrural joint

The extracellular matrix (ECM) is the main constituent of connective tissue with structural and regulatory functions, stimulating cell differentiation and proliferation. Moreover, ECM is a dynamic structure in the constant remodeling process, which is controlled by a balance between metalloproteinases (MMPs) and their inhibitors (TIMPs). Photobiomodulation (PBM) is widely described in the literature and applied in clinical practices, although its effects on ECM have not yet been elucidated. Therefore, it was evaluated if PBM could alter ECM components, such as MMP-2, -9, -13, and TIMP-2 from mice talocrural joints. Mice were divided into 3 groups (n = 6): control, PBM 3 J cm^-2, and PBM 30 J cm^-2. A low-level laser (830 nm, 10 mW, 0.05 irradiated area, energy densities 3 J cm^-2 and 30 J cm^-2, the irradiation time of 15 and 150 s, respectively, continuous wave) was applied on the joint for 4 consecutive days. mRNA levels of metalloproteinases genes (MMP-2, MMP-9, and MMP-13), their regulator (TIMP-2), and protein expressions of MMP-13 and TIMP-2 were quantified. PBM can alter only mRNA relative levels of MMP-2 at 30 J cm^-2 (p < 0.05), while MMP-9, MMP-13, and TIMP-2 mRNA relative levels did not demonstrate statistical differences for any of the groups (p > 0.05). Regarding protein expressions, MMP-13 demonstrated positive-labeled cells, only in articular cartilage, although the cell quantification did not demonstrate statistical differences when compared with the control group (p > 0.05). TIMP-2 did not present positive-labeled cells for any tissues evaluated. Our results indicate that PBM can alter MMP-2 mRNA relative level but cannot alter MMP-9, MMP-13, and TIMP mRNA relative levels. Moreover, both MMP-13 and TIMP-2 proteins were also unaltered after PBM.

Post-Translational Modification-Dependent Activity of Matrix Metalloproteinases

Due to their capacity to process different proteins of the extracellular matrix (ECM), matrix metalloproteinases (MMPs) were initially described as a family of secreted proteases, functioning as main ECM regulators. However, through proteolytic processing of various biomolecules, MMPs also modulate intra- and extracellular pathways and networks. Thereby, they are functionally implicated in the regulation of multiple physiological and pathological processes. Consequently, MMP activity is tightly regulated through a combination of epigenetic, transcriptional, and post-transcriptional control of gene expression, proteolytic activation, post-translational modifications (PTMs), and extracellular inhibition. In addition, MMPs, their substrates and ECM binding partners are frequently modified by PTMs, which suggests an important role of PTMs in modulating the pleiotropic activities of these proteases. This review summarizes the recent progress towards understanding the role of PTMs (glycosylation, phosphorylation, glycosaminoglycans) on the activity of several members of the MMP family.

Cathepsin K-deficient osteocytes prevent lactation-induced bone loss and parathyroid hormone suppression

Lactation induces bone loss to provide sufficient calcium in the milk, a process that involves osteoclastic bone resorption but also osteocytes and perilacunar resorption. The exact mechanisms by which osteocytes contribute to bone loss remain elusive. Osteocytes express genes required in osteoclasts for bone resorption, including cathepsin K (Ctsk), and lactation elevates their expression. We show that Ctsk deletion in osteocytes prevented the increase in osteocyte lacunar area seen during lactation, as well as the effects of lactation to increase osteoclast numbers and decrease trabecular bone volume, cortical thickness and mechanical properties. In addition, Ctsk deletion in osteocytes increased bone Parathyroid Hormone related Peptide (PTHrP), prevented the decrease in serum Parathyroid Hormone (PTH) induced by lactation, but amplified the increase in serum 1,25(OH)2D. The net result of these changes is to maintain serum and milk calcium levels in the normal range, ensuring normal offspring skeletal development. Our studies confirm the fundamental role of osteocytic perilacunar remodeling in physiological states of lactation and provides genetic evidence that osteocyte-derived Ctsk contributes not only to osteocyte perilacunar remodeling, but also to the regulation of PTH, PTHrP, 1,25-Dyhydroxyvitamin D (1,25(OH)2D), osteoclastogenesis and bone loss in response to the high calcium demand associated with lactation.

Matrix metalloproteinases (MMPs) and inhibitor of metalloproteinases (TIMP) mRNA and protein expression in laryngeal squamous cell carcinoma

INTRODUCTION

The aim of the study was to investigate the mRNA expression and protein levels of matrix metalloproteinases (MMP) 2 (MMP-2), 9 (MMP-9), 7 (MMP-7) and their tissue inhibitor TIMP-2 in patients with laryngeal squamous cell carcinoma and control subjects and additionally to evaluate a possible correlation with clinicopathological features.

MATERIAL AND METHODS

The expression levels of MMP-2, MMP-9, MMP-7, and TIMP-2 mRNA were detected by the real-time quantitative real time polymerase chain reaction method in 96 cases of laryngeal carcinoma vs. non-tumor tissue. The blood serum levels of MMP-2, MMP-9, MMP-7, and TIMP-2 in patients with laryngeal cancer and 100 healthy subjects were measured using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

The present study demonstrated that MMP-2, MMP-7, MMP-9 and TIMP-2 mRNA expression levels in carcinoma tissue vs. non-tumor tissue and protein levels in the preoperative serum vs. those obtained in healthy controls were statistically significantly higher than in the healthy controls (p = 0.001). The only significant correlation between mRNA or concentration of measured MMPs and TIMP and the clinicopathological features was found for TIMP-2 protein and for patients with lymph node metastasis. Serum levels of TIMP-2 were higher in cases with lymph node metastasis than in those without lymph node metastasis (p < 0.05).

CONCLUSIONS

The results may suggest that MMPs and TIMP-2 are associated with laryngeal tumorigenesis, but we did not find any distinct correlation between the clinicopathological features of laryngeal squamous cell carcinoma patients and expression levels of MMPs and TIMP. The results suggest that the measurement of serum MMP-2, MMP-7, MMP-9 and TIMP-2 concentration might be helpful to diagnose laryngeal squamous cell carcinoma.

Is it useful to use several "omics" for obtaining valuable results?

The integration of cell communication and the transfer of signals from stimuli via transcription to translation and further to activation of new protein is crucial for appropriate metabolism and function of living organisms. The overall elucidation and the examination of these complex processes require multistep laboratory approaches in order to obtain results which will not only detect particular stage but also indicate the mechanisms lying upon this process. Such results will be reliable because they will cover multidirectional methods and approaches. The analysis of currently available results already provided with the conclusion that often single omics approach does not correspond with other expected information and may bring misinterpretations. That is why the integration of several "omics" is useful for searching entire explanations and answers as well as appropriate interpretation of obtained complex results. The hypothesis was stated that "from transcriptomics can not be concluded to proteomics". This review focuses on the reasons for the integration of transcriptomic, proteomic and other-omics analysis. Moreover it also describes the examples of clinical meanings and mentions some methods used in these approaches.

Glycosaminoglycans influence enzyme activity of MMP2 and MMP2/TIMP3 complex formation - Insights at cellular and molecular level

The extracellular matrix (ECM) is a highly dynamic network constantly remodeled by a fine-tuned protein formation and degradation balance. Matrix metalloproteinases (MMPs) constitute key orchestrators of ECM degradation. Their activity is controlled by tissue inhibitors of metalloproteinases (TIMPs) and glycosaminoglycans (GAG). Here, we investigated the molecular interplay of MMP2 with different GAG (chondroitin sulfate, hyaluronan (HA), sulfated hyaluronan (SH) and heparin (HE)) and the impact of GAG on MMP2/TIMP3 complex formation using in vitro-experiments with human bone marrow stromal cells, in silico docking and molecular dynamics simulations. SH and HE influenced MMP2 and TIMP3 protein levels and MMP2 activity. Only SH supported the alignment of both proteins in fibrillar-like structures, which, based on our molecular models, would be due to a stabilization of the interactions between MMP2-hemopexin domain and TIMP3-C-terminal tail. Dependent on the temporal sequential order in which the final ternary complex was formed, our models indicated that SH and HA can affect TIMP3-induced MMP2 inhibition through precluding or supporting their interactions, respectively. Our combined experimental and theoretical approach provides valuable new insights on how GAG interfere with MMP2 activity and MMP2/TIMP3 complex formation. The results obtained evidence GAG as promising molecules for fine-balanced intervention of ECM remodeling.

Behavior of Metalloproteinases in Adipose Tissue, Liver and Arterial Wall: An Update of Extracellular Matrix Remodeling

Extracellular matrix (ECM) remodeling is required for many physiological and pathological processes. Metalloproteinases (MMPs) are endopeptidases which are able to degrade different components of the ECM and nucleus matrix and to cleave numerous non-ECM proteins. Among pathological processes, MMPs are involved in adipose tissue expansion, liver fibrosis, and atherosclerotic plaque development and vulnerability. The expression and the activity of these enzymes are regulated by different hormones and growth factors, such as insulin, leptin, and adiponectin. The controversial results reported up to this moment regarding MMPs behavior in ECM biology could be consequence of the different expression patterns among species and the stage of the studied pathology. The aim of the present review was to update the knowledge of the role of MMPs and its inhibitors in ECM remodeling in high incidence pathologies such as obesity, liver fibrosis, and cardiovascular disease.

Suppression of PMA-induced human fibrosarcoma HT-1080 invasion and metastasis by kahweol via inhibiting Akt/JNK1/2/p38 MAPK signal pathway and NF-κB dependent transcriptional activities

Coffee is one of the widely sales beverage worldwide and contains numerous phytochemicals that are beneficial to health. Kahweol acetate (KA), a coffee-specific diterpene, exhibits anti-tumoric properties in human tumoric cells. However, the effect of KA on the metastasis and invasion of cancer cells and the underlying mechanisms remain unclear. The objectives of this study were to estimate the anti-tumor activity of KA and reveal the possible molecular mechanisms. KA markedly inhibited the cell proliferation enhanced by phorbol 12-myristate 13-acetate (PMA) in human fibrosarcoma cells. As well as, KA attenuated PMA-induced cell migration and invasion in a concentration-dependent manner. KA suppressed PMA-enhanced activation of matrix metalloproteinase-9 (MMP-9) through suppression of nuclear factor kappa B (NF-κB) activation. KA repressed the PMA-induced phosphorylation of Akt, c-Jun N-terminal kinase (JNK) 1/2, and p38 MAPK, which are signaling molecules upstream of MMP-9 expression. In summary, we demonstrated that the anti-tumor effects of KA might occur through the inhibition of Akt/JNK1/2/p38 MAPK phosphorylation and downregulation of NF-κB activation, leading to a decrease in MMP-9 expression. Thus, KA is a useful chemotherapeutic agent that may contribute to prevent to the metastatic tumor.

The dual effect of morphine on tumor development

Morphine is a classic opioid drug used for reducing pain and is commonly prescribed as an effective drug to control cancer pain. Morphine has a direct role in the central nervous system to relieve pain, but because of its peripheral functions, morphine also has some side effects, such as nausea, constipation, and addiction (Gupta et al. in Sci World J 2015:10, 2015). In addition to its analgesic effect, the role of morphine in tumor development is an important question that has been investigated for many years with conflicting results. Numerous studies suggest that morphine has a role in both promoting and inhibiting tumor growth. In this extensive review, we attempt to comprehensively understand the effects of morphine and summarize both its positive and negative influences on various aspects of tumors, including tumor growth, angiogenesis, metastasis, inflammation, and immunomodulation.

Expression of gelatinases (MMP-2 and MMP-9) and tissue inhibitors of metalloproteinases (TIMP-2 and TIMP-3) in the chicken ovary in relation to follicle development and atresia

Matrix metalloproteinases (MMPs) are a family of peptidases that possess the ability to break down extracellular matrix macromolecules associated with tissue turnover in various physiological and pathological conditions. Their activity is largely regulated by specific tissue inhibitors of MMPs (TIMPs). Information concerning the role of MMPs in the chicken ovary is very limited. The aim of the present study was to determine the expression and localization of selected members of the MMP system in different compartments of the laying hen ovary and to investigate whether their expression changes at different stages of the ovulatory cycle. MMP-2 and -9 activity was also examined. Expression of MMP-2, -9 and tissue inhibitors of MMPs (TIMP-2 and -3) in the ovarian follicles was examined 22 h and 3 h before F1 ovulation. Real-time polymerase chain reaction and western blot revealed differential mRNA and protein expression of MMP-2, MMP-9, TIMP-2, and TIMP-3 in the ovarian follicles: white, yellowish, small yellow, the largest preovulatory (F3-F1), and white atretic. Within the ovary, the relative expression of MMP and TIMP mRNA depended on follicle development, the layer of follicular wall, and ovulation stage. The relatively higher expression of MMP-2 and MMP-9 mRNA in the ovarian follicles 3 h compared to 22 h before ovulation was found. As follicle development progressed toward ovulation, elevated MMP-2 and -9 activity was noted. Atresia of white follicles was accompanied by an increase in gelatinase activities. Immunohistochemistry demonstrated tissue- and follicle-dependent immunoreactivity of the examined MMPs and TIMPs. In summary, the results show tissue- and stage of the ovulatory cycle-dependent differences in MMP and TIMP expression, as well as MMP-2 and -9 activity. Findings that suggest these molecules might significantly participate in the complex remodeling of extracellular matrix required for follicle development, ovulation, and atresia in the chicken ovary.

Reflections on the evolution of the vertebrate tissue inhibitors of metalloproteinases

Jawed vertebrates (Gnathostomes) have 4 tissue inhibitors of metalloproteinases (TIMPs), multifunctional proteins that all inhibit members of the large matrix metalloproteinase (MMP) family but differ in their other roles, including the regulation of pro-MMP activation, cell growth, apoptosis and angiogenesis, and the structure of extracellular matrices (ECMs). Molecular phylogeny analyses indicate that vertebrate TIMP genes arose from an invertebrate ancestor through 3 successive duplications, possibly including 2 whole genome duplications, during early vertebrate phylogeny. TIMPs from invertebrates also inhibit metalloproteinases, bind to pro-MMPs, and contribute to ECM structures but are not orthologs of any particular vertebrate TIMP. The most ancient vertebrate superclass, the Agnatha (jawless fish), seems to provide a snapshot of a stage in TIMP evolution preceding the third gene duplication. This review examines the structures of TIMPs from different vertebrate orders using information relating to the structural basis of their various functions. Provisional conclusions are that during their evolutionary divergence, various TIMPs lost inhibitory activity toward some metalloproteinases, specialized in effects on different pro-MMPs, and developed new interactions with discrete targets (including integrins and receptors), while recapitulating a role in ECM structure. The analysis is limited by the sparse information available regarding the functional properties of nonmammalian TIMPs.-Brew, K. Reflections on the evolution of the vertebrate tissue inhibitors of metalloproteinases.

IFITM3 promotes hepatocellular carcinoma invasion and metastasis by regulating MMP9 through p38/MAPK signaling

Interferon-induced transmembrane protein 3 (IFITM3) has been shown to be overexpressed in multiple cancers. However, the role of IFITM3 in metastasis of hepatocellular carcinoma (HCC) is still poorly understood. In this study, we showed that IFITM3 was frequently overexpressed in HCC tissues compared with adjacent nontumor tissues. Overexpression of IFITM3 was significantly correlated with tumor metastasis and poor prognosis in HCC. Knockdown of IFITM3 dramatically decreased MMP9 expression and inhibited the invasion and metastasis of HCC in vitro and in vivo. Moreover, the upregulation of MMP9 rescued the decreased migration and invasion induced by the knockdown of IFITM3, whereas the knockdown of MMP9 decreased IFITM3-enhanced HCC migration and invasion. Mechanistically, we found that IFITM3 regulates MMP9 expression through the p38/MAPK pathway. Taken together, we identified a novel IFITM3-p38/MAPK-MMP9 regulatory circuitry, the dysfunction of which drives invasive and metastatic character in HCC.

Interaction of the cryptic fragment of myelin basic protein with mitochondrial voltage-dependent anion-selective channel-1 affects cell energy metabolism

In demyelinating nervous system disorders, myelin basic protein (MBP), a major component of the myelin sheath, is proteolyzed and its fragments are released in the neural environment. Here, we demonstrated that, in contrast with MBP, the cellular uptake of the cryptic 84-104 epitope (MBP84-104) did not involve the low-density lipoprotein receptor-related protein-1, a scavenger receptor. Our pull-down assay, mass spectrometry and molecular modeling studies suggested that, similar with many other unfolded and aberrant proteins and peptides, the internalized MBP84-104 was capable of binding to the voltage-dependent anion-selective channel-1 (VDAC-1), a mitochondrial porin. Molecular modeling suggested that MBP84-104 directly binds to the N-terminal α-helix located midway inside the 19 β-blade barrel of VDAC-1. These interactions may have affected the mitochondrial functions and energy metabolism in multiple cell types. Notably, MBP84-104 caused neither cell apoptosis nor affected the total cellular ATP levels, but repressed the aerobic glycolysis (lactic acid fermentation) and decreased the l-lactate/d-glucose ratio (also termed as the Warburg effect) in normal and cancer cells. Overall, our findings implied that because of its interactions with VDAC-1, the cryptic MBP84-104 peptide invoked reprogramming of the cellular energy metabolism that favored enhanced cellular activity, rather than apoptotic cell death. We concluded that the released MBP84-104 peptide, internalized by the cells, contributes to the reprogramming of the energy-generating pathways in multiple cell types.

RNA interference screening identifies clathrin-B and cofilin-1 as mediators of MT1-MMP in endometrial cancer

The matrix metalloproteinases (MMPs) are implicated in tumor invasion and metastasis. Given their multiple tumor promoting roles, MMPs are promising targets for the treatment of metastatic cancer. Using a siRNA library screen of 140 membrane trafficking genes, we identified 41 genes in HEC-1B and 36 in Ishikawa cancer cells that decreased metalloproteinases activity. The 16 genes common in both cancer cell lines that decreased MMPs activity are involved in cargo sorting, vesicle formation and vesicle recycling. The top two genes clathrin-B and cofilin-1 were chosen for post hoc functional studies. Higher expression of both genes was confirmed in cancer cells and knockdown with respective siRNAs inhibited their invasive potential and matrix metalloproteinases activity. Membrane Type 1- Matrix Metalloproteinase (MT1-MMP) is a master switch proteinase and regulator of invasion and metastasis. A marked decrease in MT1-MMP expression and activity was seen in clathrin-B and cofilin-1 knockdown cancer cells which was associated with a marked decreased expression of invadopodia formation proteins. Our results suggest that the decreased expression of clathrin-B and cofilin-1 decreases the expression of MT1-MMP and results in attenuation of MT1-MMP at the cell surface, thus inhibiting tumor cell invasion and metastasis.

Prodigiosin produced by Serratia marcescens inhibits expression of MMP-9 and survivin and promotes caspase-3 activation with induction of apoptosis in acute lymphoblastic leukaemia cells

AIMS

Matrix metalloproteinase-9 (MMP-9) and survivin are involved in several steps of carcinogenesis in acute lymphoblastic leukaemia (ALL). Yet, no MMP-9 and survivin-modulating drugs with low toxicity on normal cells but high efficacy against high MMP-9- and survivin-expressing leukaemia cells have been approved for clinical application in ALL. Prodigiosin, a secondary metabolite of Serratia marcescens, induces apoptosis in different kinds of cancer cells with low toxicity on normal cells. However, little is known about the effects of this compound on the high MMP-9- and survivin-expressing leukaemia cells.

METHODS AND RESULTS

CCRF-CEM cells as a model for high MMP-9- and survivin-expressing ALL cells were treated with 100, 200 and 400 nmol l^-1 prodigiosin after which cell number, proliferation rate, MMP-9 and survivin expression, caspase-3 activation and apoptosis were evaluated. After 24-, 48-, and 72-h treatments with 100, 200 and 400 nmol l^-1 prodigiosin, proliferation rates were measured to be 92·3-76·7%, 82-63% and 63·7-46·6% respectively. Treatment with prodigiosin for 48 h decreased MMP-9 mRNA levels followed by decreases in secreted (S) and intracellular (I) MMP-9 protein levels by 20-22% and 69-72% for 100-400 nmol l^-1 prodigiosin respectively. Prodigiosin decreased survivin protein levels from 40 to 26% followed by 3·7-5·6-fold increases in caspase-3 activation for the aforementioned prodigiosin concentration ranges. Treatment with 100-400 nmol l^-1 prodigiosin increased the caspase-3/survivin, caspase-3/I-MMP-9 and caspase-3/S-MMP-9 ratios by 6-7·3-, 11·5-19·1- and 4·9-6·8-fold increases respectively. A dramatic increase in the number of apoptotic cells was also observed with increasing prodigiosin concentrations.

CONCLUSION

The inhibitory effects of prodigiosin on MMP-9 and survivin expression, as well as its pro-apoptotic capacity, represent a novel therapeutic avenue against ALL cells.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings provide an important and interesting basis to develop a new therapeutic compound with high potential against ALL cells.

Phenotypic instability of chondrocytes in osteoarthritis: on a path to hypertrophy

Articular chondrocytes are quiescent, fully differentiated cells responsible for the homeostasis of adult articular cartilage by maintaining cellular survival functions and the fine-tuned balance between anabolic and catabolic functions. This balance requires phenotypic stability that is lost in osteoarthritis (OA), a disease that affects and involves all joint tissues and especially impacts articular cartilage structural integrity. In OA, articular chondrocytes respond to the accumulation of injurious biochemical and biomechanical insults by shifting toward a degradative and hypertrophy-like state, involving abnormal matrix production and increased aggrecanase and collagenase activities. Hypertrophy is a necessary, transient developmental stage in growth plate chondrocytes that culminates in bone formation; in OA, however, chondrocyte hypertrophy is catastrophic and it is believed to initiate and perpetuate a cascade of events that ultimately result in permanent cartilage damage. Emphasizing changes in DNA methylation status and alterations in NF-κB signaling in OA, this review summarizes the data from the literature highlighting the loss of phenotypic stability and the hypertrophic differentiation of OA chondrocytes as central contributing factors to OA pathogenesis.

High Resolution Proteomic Analysis of the Cervical Cancer Cell Lines Secretome Documents Deregulation of Multiple Proteases

BACKGROUND

Oncogenic infection by HPV, eventually leads to cervical carcinogenesis, associated by deregulation of specific pathways and protein expression at the intracellular and secretome level. Thus, secretome analysis can elucidate the biological mechanisms contributing to cervical cancer. In the present study we systematically analyzed its constitution in four cervical cell lines employing a highly sensitive proteomic technology coupled with bioinformatics analysis.

MATERIALS AND METHODS

LC/MS-MS proteomics and bioinformatics analysis were performed in the secretome of four informative cervical cell lines SiHa (HPV16⁺), HeLa (HPV18⁺), C33A (HPV^-) and HCK1T (normal).

RESULTS

The proteomic pattern of each cancer cell line compared to HCK1T was identified and a detailed bioinformatics analysis disclosed inhibition of matrix metalloproteases in cancer cell lines. This prediction was further confirmed via zymography for MMP-2 and MMP-9, western blot analysis for ADAM10 and by MRM for TIMP1. The differential expression of important secreted proteins such as CATD, FUCA1 and SOD2 was also confirmed by western blot analysis. MRM-targeted proteomics analysis confirmed the differential expression of CATD, CATB, SOD2, QPCT and NEU1.

CONCLUSION

High resolution proteomics analysis of cervical cancer secretome revealed significantly deregulated biological processes and proteins implicated in cervical carcinogenesis.

Nucleic acid-induced potentiation of matrix metalloproteinase-9 enzymatic activity

Matrix metalloproteinases (MMPs) play varied roles in normal biology and diseases where, depending on the context, both inhibition and enhancement of the enzymatic activity may be beneficial. However, there are very few reports of positive modulators of MMP activity. We report that polynucleotides, including single-stranded DNA, RNA, and even double-stranded DNA, bind to and enhance the enzymatic activity of MMP9. This enhancement of MMP9 catalytic activity is not shared by biologically active polycationic molecules suggesting nonspecific charge screening as an unlikely mechanism. Deletion construct and MMP1, 2, and 3 studies suggest that the type-II fibronectin repeat domains of the enzyme appear to play a role in mediating the nucleotide potentiation of MMP9 activity. Single-stranded DNA enhances nerve growth factor-induced MMP9-dependent neurite extension in pheochromocytoma 12 cells providing evidence for potential biological significance of the nucleotide-mediated allosteric enhancement of the catalytic activity.

Involvement of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitors (TIMP-2, -3) in the regression of chicken postovulatory follicles

The study was undertaken to examine mRNA expression and localization of selected matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), and the activity of MMPs in chicken postovulatory follicles (POFs) during their apoptotic regression. Apoptotic cells and apoptosis-related caspase expression and activity were examined as well. Chickens were sacrificed 2 h and 21 h after ovulation, and five POFs (POF1 to POF5) were isolated from the ovaries. It was found that the number of apoptotic cells (TUNEL-positive) increased along with follicle regression. The relative expression (RQ) of caspase-2, -3, -8 and -9 mRNA increased (P < 0.05) in POF5, while the activity of all examined caspases elevated gradually (approximately 80-150%) reaching the highest level in POF3, and then slowly decreased to the value noted in POF1 (P < 0.05 - P < 0.001). Real-time polymerase chain reaction revealed different expression of MMP-2, -7, -9 and TIMP-2 and -3 on mRNA levels, and activity assay showed the changes in activity of MMP-2 and -9 in the POFs. Regression of the follicles was accompanied predominantly by an increase in the relative expression of MMP-2, and a decrease in TIMP-2 and -3 mRNAs (P < 0.05 - P < 0.001). The activity levels of MMP-2 and -9 showed pronounced changes during the examined period. During follicle regression elevated activity of MMP-2 and -9 was found (P < 0.05 - P < 0.001). Immunohistochemistry demonstrated tissue- and follicle-dependent immunoreactivity of the examined members of the MMP system. In summary, the results showing the apoptotic regression-related changes as well as tissue-dependent differences in the expression of selected MMPs and TIMPs, and activity of MMP-2 and MMP-9, point to the significance that these molecules might participate in the complex orchestration of chicken POF regression.

Dysregulation of fibrosis related genes in HCV induced liver disease

BACKGROUND

Liver fibrosis results from a wound healing response to chronic injury, which leads to excessive matrix deposition. Genome wide association studies have showen transcriptional dysregulation in mild and severe liver fibrosis. Recent studies suggested that genetic markers may be able to define the exact stage of liver fibrosis.

AIM

To define genes or genetic pathways that could serve as markers for staging or as therapeutic targets to halt progression of liver fibrosis.

METHODS

The study was performed on 105 treatment naïve HCV genotype 4 infected patients [F0-F2, n = 56; F3-F4, n = 49] and 16 healthy subjects. The study included PCR array on 84 fibrosis related genes followed by customization of a smaller array consisting of 11 genes that were designed on the bases of results obtained from the larger array. Genes that displayed significant dysregulation at mRNA levels were validated at protein levels.

RESULTS AND DISCUSSION

Two major pathways exhibited high dysregulation in early fibrosis as compared with controls or when compared with late fibrosis, these were the TGFβ - related pathway genes and Matrix - deposition associated genes. Hepatic stellate cell (HSC) activators i.e. TGFβ pathway genes [TGFβ1, 2 and 3, their receptors TGFβR1 and 2, signaling molecules SMAD genes and PDGF growth factors] were considerably over-expressed at transcriptional levels as early as F0, whereas expression of their inhibitor TGIF1 was simultaneously down regulated. Matrix proteins including collagen and MMPs were upregulated in early fibrosis whereas tissue inhibitors TIMPs 1 and 2 began over expression in late fibrosis. Expression at protein levels was concordant with RNA data excluding dysregulation at post transcriptional levels.

CONCLUSION

Since these 2 gene sets are closely interrelated regarding HSC activation and proliferation, we assume that the current findings suggest that they are favorable targets to further search for stage specific markers.

Fragments generated upon extracellular matrix remodeling: Biological regulators and potential drugs

The remodeling of the extracellular matrix (ECM) by several protease families releases a number of bioactive fragments, which regulate numerous biological processes such as autophagy, angiogenesis, adipogenesis, fibrosis, tumor growth, metastasis and wound healing. We review here the proteases which generate bioactive ECM fragments, their ECM substrates, the major bioactive ECM fragments, together with their biological properties and their receptors. The translation of ECM fragments into drugs is challenging and would take advantage of an integrative approach to optimize the design of pre-clinical and clinical studies. This could be done by building the contextualized interaction network of the ECM fragment repertoire including their parent proteins, remodeling proteinases, and their receptors, and by using mathematical disease models.

Reperfusion therapy-What's with the obstructed, leaky and broken capillaries?

Microvascular dysfunction is well established as an early and rate-determining factor in the injury response of tissues to ischemia and reperfusion (I/R). Severe endothelial cell dysfunction, which can develop without obvious morphological cell injury, is a major underlying cause of the microvascular abnormalities that accompany I/R. While I/R-induced microvascular dysfunction is manifested in different ways, two responses that have received much attention in both the experimental and clinical setting are impaired capillary perfusion (no-reflow) and endothelial barrier failure with a transition to hemorrhage. These responses are emerging as potentially important determinants of the severity of the tissue injury response, and there is growing clinical evidence that they are predictive of clinical outcome following reperfusion therapy. This review provides a summary of animal studies that have focused on the mechanisms that may underlie the genesis of no-reflow and hemorrhage following reperfusion of ischemic tissues, and addresses the clinical evidence that implicates these vascular events in the responses of the ischemic brain (stroke) and heart (myocardial infarction) to reperfusion therapy. Inasmuch as reactive oxygen species (ROS) and matrix metalloproteinases (MMP) are frequently invoked as triggers of the microvascular dysfunction elicited by I/R, the potential roles and sources of these mediators are also discussed. The available evidence in the literature justifies the increased interest in the development of no-reflow and hemorrhage in heart and brain following reperfusion therapy, and suggests that these vascular events may be predictive of poor clinical outcome and warrant the development of targeted treatment strategies.

New Insights into the Role of Matrix Metalloproteinases in Preeclampsia

Preeclampsia is a severe pregnancy complication globally, characterized by poor placentation triggering vascular dysfunction. Matrix metalloproteinases (MMPs) exhibit proteolytic activity implicated in the efficiency of trophoblast invasion to the uterine wall, and a dysregulation of these enzymes has been linked to preeclampsia. A decrease in MMP-2 and MMP-9 interferes with the normal remodeling of spiral arteries at early pregnancy stages, leading to the initial pathophysiological changes observed in preeclampsia. Later in pregnancy, an elevation in MMP-2 and MMP-9 induces abnormal release of vasoactive factors conditioning hypertension. Although these two enzymes lead the scene, other MMPs like MMP-1 and MMP-14 seem to have a role in this pathology. This review gathers published recent evidence about the implications of different MMPs in preeclampsia, and the potential use of these enzymes as emergent biomarkers and biological therapeutic targets, focusing on studies involving human subjects.

Metalloproteinases: a Functional Pathway for Myeloid Cells

Myeloid cells have diverse roles in regulating immunity, inflammation, and extracellular matrix turnover. To accomplish these tasks, myeloid cells carry an arsenal of metalloproteinases, which include the matrix metalloproteinases and the adamalysins. These enzymes have diverse substrate repertoires, and are thus involved in mediating proteolytic cascades, cell migration, and cell signaling. Dysregulation of metalloproteinases contributes to pathogenic processes, including inflammation, fibrosis, and cancer. Metalloproteinases also have important nonproteolytic functions in controlling cytoskeletal dynamics during macrophage fusion and enhancing transcription to promote antiviral immunity. This review highlights the diverse contributions of metalloproteinases to myeloid cell functions.

Maternal lactocrine programming of porcine reproductive tract development

The lactocrine hypothesis for maternal programming of female reproductive tract development is based on the idea that non-nutritive, milk-borne bioactive factors (MbFs), delivered from mother to offspring during nursing, play a role in determining the trajectory of development with long-term consequences in the adult. Porcine female reproductive tract development is completed postnatally, and the period during which maternal support of neonatal growth derives exclusively from colostrum/milk defines a window of opportunity for lactocrine programming of reproductive tissues. Beyond nutrition, milk serves as a delivery system for a variety of bioactive factors. Porcine relaxin is a prototypical MbF. Present in colostrum at highest concentrations at birth, relaxin is transmitted into the circulation of nursing piglets where it can act on Relaxin receptors found in neonatal female reproductive tract tissues. This process is facilitated by the physiology of the maternal-neonatal dyad and the fact that the neonatal gastrointestinal tract is open to absorb macromolecules for a period of time postnatally. Age at first nursing and duration of nursing from birth are also important for porcine female reproductive tract development. These parameters affect both the quality and quantity of colostrum consumed. Disruption of lactocrine signaling by feeding milk replacer from birth altered porcine uterine, cervical, and testicular development by postnatal Day 2. Moreover, insufficient colostrum consumption in nursing piglets can impair uterine capacity to support viable litters of optimal size in adulthood. In the pig, lactocrine signaling supports neonatal organizational events associated with normal reproductive development and may program adult uterine capacity.

Secreted tissue inhibitor of matrix metalloproteinase restricts trans-synaptic signaling to coordinate synaptogenesis

Synaptogenesis is coordinated by trans-synaptic signals that traverse the specialized synaptomatrix between presynaptic and postsynaptic cells. Matrix metalloproteinase (Mmp) activity sculpts this environment, balanced by secreted tissue inhibitors of Mmp (Timp). Here, we use the simplified Drosophila melanogaster matrix metalloproteome to test the consequences of eliminating all Timp regulatory control of Mmp activity at the neuromuscular junction (NMJ). Using in situ zymography, we find Timp limits Mmp activity at the NMJ terminal and shapes extracellular proteolytic dynamics surrounding individual synaptic boutons. In newly generated timp null mutants, NMJs exhibit architectural overelaboration with supernumerary synaptic boutons. With cell-targeted RNAi and rescue studies, we find that postsynaptic Timp limits presynaptic architecture. Functionally, timp null mutants exhibit compromised synaptic vesicle cycling, with activity that is lower in amplitude and fidelity. NMJ defects manifest in impaired locomotor function. Mechanistically, we find that Timp limits BMP trans-synaptic signaling and the downstream synapse-to-nucleus signal transduction. Pharmacologically restoring Mmp inhibition in timp null mutants corrects bone morphogenetic protein (BMP) signaling and synaptic properties. Genetically restoring BMP signaling in timp null mutants corrects NMJ structure and motor function. Thus, Timp inhibition of Mmp proteolytic activity restricts BMP trans-synaptic signaling to coordinate synaptogenesis.

The effect of biological sealants and adhesive treatments on matrix metalloproteinase expression during renal injury healing

Background

Renal injuries are relatively common in cases of abdominal trauma. Adhesives and sealants can be used to repair and preserve damaged organs. Using a rat model, this study explores the activity of different matrix metalloproteinases (MMP) during the healing of renal injuries treated by two biological adhesives (TachoSil and GelitaSpon) and a new synthetic elastic cyanoacrylate (Adhflex).

Methods

Renal traumatic injuries were experimentally induced in 90 male Wistar rats by a Stiefel Biopsy Punch in the anterior aspect of the left kidney. Animals were divided into five groups: 1, sham non-injured (n = 3); 2, non-treated standard punch injury (n = 6); 3, punch injury treated with TachoSil (n = 27); 4, punch injury treated with GelitaSpon (n = 27); and, 5, punch injury treated with Adhflex (n = 27). Wound healing was evaluated 2, 6, and 18 days after injury by determining the expression of MMPs, and the histopathological evolution of lesions.

Findings

Histologically, the wound size at 6 days post-injury was larger in Adhflex-treated samples than in the other treatments, but the scarring tissue was similar at 18 days post-injury. Only the MMPs subtypes 1, 2, 8, 9, and 13 were sufficiently expressed to be quantifiable. Both time since injury and treatment type had a significant influence on MMPs expression. Two days after injury, the expression of MMP8 and MMP9 was predominant. MMP2 expression was greater 6 days after injury. The Adhflex-treated group had a significantly higher MMPs expression than the other treatment groups at all healing stages.

Conclusions

All three sealant treatments induced almost similar expression of MMPs than untreated animals indicating a physiological healing process. Given that all renal trauma injuries must be considered emergencies, both biological and synthetic adhesives, such as Adhflex, should be considered as a treatment options.

The soluble protease ADAMDEC1 released from activated platelets hydrolyzes platelet membrane pro-epidermal growth factor (EGF) to active high-molecular-weight EGF

Platelets are the sole source of EGF in circulation, yet how EGF is stored or released from stimulated cells is undefined. In fact, we found platelets did not store EGF, synthesized as a single 6-kDa domain in pro-EGF, but rather expressed intact pro-EGF precursor on granular and plasma membranes. Activated platelets released high-molecular-weight (HMW)-EGF, produced by a single cleavage between the EGF and the transmembrane domains of pro-EGF. We synthesized a fluorogenic peptide encompassing residues surrounding the putative sessile arginyl residue and found stimulated platelets released soluble activity that cleaved this pro-EGF_1020-1027 peptide. High throughput screening identified chymostatins, bacterial peptides with a central cyclic arginyl structure, as inhibitors of this activity. In contrast, the matrix metalloproteinase/TACE (tumor necrosis factor-α-converting enzyme) inhibitor GM6001 was ineffective. Stimulated platelets released the soluble protease ADAMDEC1, recombinant ADAMDEC1 hydrolyzed pro-EGF_1020-1027, and this activity was inhibited by chymostatin and not GM6001. Biotinylating platelet surface proteins showed ADAMDEC1 hydrolyzed surface pro-EGF to HMW-EGF that stimulated HeLa EGF receptor (EGFR) reporter cells and EGFR-dependent tumor cell migration. This proteolysis was inhibited by chymostatin and not GM6001. Metabolizing pro-EGF Arg¹⁰²³ to citrulline with recombinant polypeptide arginine deiminase 4 (PAD4) abolished ADAMDEC1-catalyzed pro-EGF_1020-1027 peptidolysis, while pretreating intact platelets with PAD4 suppressed ADAMDEC1-, thrombin-, or collagen-induced release of HMW-EGF. We conclude that activated platelets release ADAMDEC1, which hydrolyzes pro-EGF to soluble HMW-EGF, that HMW-EGF is active, that proteolytic cleavage of pro-EGF first occurs at the C-terminal arginyl residue of the EGF domain, and that proteolysis is the regulated and rate-limiting step in generating soluble EGF bioactivity from activated platelets.

Spondyloarthritis: Matrix Metalloproteinasesas Biomarkers of Pathogenesis and Response to Tumor Necrosis Factor (TNF) Inhibitors

The term spondyloarthritis (SpA) is used to describe a group of multifactorial chronic inflammatory diseases characterized by a predisposing genetic background and clinical manifestations typically involving the sacroiliac joint. The absence of pathognomonic clinical and/or laboratory findings generally results in a delay in diagnosis and, consequently, in treatment. In addition, 20–40% of SpA patients are non-responders to tumor necrosis factor (TNF) inhibitor therapies. Given these considerations, it is important to identify biomarkers that can facilitate the diagnosis and assessment of disease activity. As inflammation plays a key role in the pathogenesis of SpA, inflammatory mediators have been investigated as potential biomarkers for diagnosing the disease and predicting response to therapy. Some investigators have focused their attention on the role of matrix metalloproteinases (MMPs), which are known to be markers of synovial inflammation that is generated in the joint in reaction to inflammatory stimuli. Several studies have been carried out to verify if serum MMPs levels could be useful to diagnose SpA, to assess disease severity, and to predict response to TNF inhibitor therapy. The current review focuses on MMPs’ role in SpA pathogenesis, diagnosis and therapeutic implications.

Relationship among LRP1 expression, Pyk2 phosphorylation and MMP-9 activation in left ventricular remodelling after myocardial infarction

Left ventricular (LV) remodelling after myocardial infarction (MI) is a crucial determinant of the clinical course of heart failure. Matrix metalloproteinase (MMP) activation is strongly associated with LV remodelling after MI. Elucidation of plasma membrane receptors related to the activation of specific MMPs is fundamental for treating adverse cardiac remodelling after MI. The aim of current investigation was to explore the potential association between the low‐density lipoprotein receptor‐related protein 1 (LRP1) and MMP‐9 and MMP‐2 spatiotemporal expression after MI. Real‐time PCR and Western blot analyses showed that LRP1 mRNA and protein expression levels, respectively, were significantly increased in peri‐infarct and infarct zones at 10 and 21 days after MI. Confocal microscopy demonstrated high colocalization between LRP1 and the fibroblast marker vimentin, indicating that LRP1 is mostly expressed by cardiac fibroblasts in peri‐infarct and infarct areas. LRP1 also colocalized with proline‐rich tyrosine kinase 2 (pPyk2) and MMP‐9 in cardiac fibroblasts in ischaemic areas at 10 and 21 days after MI. Cell culture experiments revealed that hypoxia increases LRP1, pPyk2 protein levels and MMP‐9 activity in fibroblasts, without significant changes in MMP‐2 activity. MMP‐9 activation by hypoxia requires LRP1 and Pyk2 phosphorylation in fibroblasts. Collectively, our in vivo and in vitro data support a major role of cardiac fibroblast LRP1 levels on MMP‐9 up‐regulation associated with ventricular remodelling after MI.

Timing and duration of nursing from birth affect neonatal porcine uterine matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1

Nursing for 2 d from birth supports neonatal porcine uterine and cervical development. However, it is not clear how timing or duration of lactocrine signaling from birth (postnatal day = PND 0) affects development of neonatal female reproductive tract tissues. Therefore, studies were conducted to determine effects of age at first nursing and duration of nursing from birth on specific elements of the matrix metalloproteinase (MMP)/tissue inhibitor of metalloproteinase (TIMP) system in uterine and cervical tissues at PND 2. When nursing was initiated at 0 h or 30 min of age, targeted proteins, including proMMP9 and MMP9, were detected in uterine and cervical tissues on PND 2, as was uterine TIMP1. However, these proteins were undetectable when nursing was delayed for 12 h and when gilts were fed milk replacer for 48 h from birth. Increasing the duration of nursing from 30 min to 12 h from birth increased uterine (P < 0.05) and cervical (P < 0.001) MMP9 levels to those observed in gilts nursed for 48 h. Similarly, uterine TIMP1 levels increased with duration of nursing. Uterine MMP2 levels were detectable but unaffected by age at first nursing or duration of nursing from birth. Uterine MMP2 and MMP9 activities, monitored by zymography, reflected immunoblotting data. Results provide evidence for the utility of MMP9 and TIMP1 as markers of age- and lactocrine-sensitive porcine female reproductive tract development.

Development of a monoclonal anti-ADAMTS-5 antibody that specifically blocks the interaction with LRP1

The potent aggrecanase ADAMTS-5 is constitutively secreted by chondrocytes, but it is rapidly endocytosed in normal cartilage via the cell surface endocytic receptor LRP1. Therefore it is difficult to detect the total ADAMTS-5 activity produced. In this study, we isolated a monoclonal anti-ADAMTS-5 antibody 1B7 that blocks LRP1-mediated internalization without affecting the aggrecanolytic activity. Addition of 1B7 to cultured human chondrocytes revealed the full aggrecanolytic activity of ADAMTS-5 generated by the cells. 1B7 is a useful tool to estimate the ADAMTS-5 activity and to identify its potential roles in the tissues.

Riding the metalloproteinase roller coaster

To many of us in the field, working on matrix metalloproteinases (MMPs) has felt like riding a roller coaster, traveling through times of both excitement and despair. I was fortunate to join the ride when it was a mere carousel of three activities thought to target the proteins that comprise the extracellular matrix (ECM). New technologies brought the thrills of discovery as we uncovered specific proteinase genes and defined specialized activities in different cellular processes. The MMPs and the sister families of "adisintegrin and metalloproteinase" (ADAMs), ADAMs with thrombospondin domains (ADAM-TS), and Astacins are now recognized as key signaling "scissors" that drive rapid changes in a plethora of cellular pathways. My many excellent colleagues and collaborators and I were enthused to contribute to the early development of the field and continue to be amazed at its growth and sophistication. In contrast, the hype and failure of early inhibitor discovery have dogged our standing with the pharmaceutical industry and grant-giving bodies. However, the true believers have kept going, and knowledge of particular functions of MMPs and their contributions to disease progression has progressed. Recognition of the strategic importance of proteinase function should inspire more work harnessing new technologies such as imaging, proteomics, and gene editing to generate a more precise understanding of individual situations. New approaches to inhibitor design and assessment are possible, and the consequent ability to precisely abrogate specific MMP activity could contribute to the fight against a number of pathologies with unmet needs. What a ride it could be!

Cancer cell behaviors mediated by dysregulated pH dynamics at a glance

Dysregulated pH is a common characteristic of cancer cells, as they have an increased intracellular pH (pHi) and a decreased extracellular pH (pHe) compared with normal cells. Recent work has expanded our knowledge of how dysregulated pH dynamics influences cancer cell behaviors, including proliferation, metastasis, metabolic adaptation and tumorigenesis. Emerging data suggest that the dysregulated pH of cancers enables these specific cell behaviors by altering the structure and function of selective pH-sensitive proteins, termed pH sensors. Recent findings also show that, by blocking pHi increases, cancer cell behaviors can be attenuated. This suggests ion transporter inhibition as an effective therapeutic approach, either singly or in combination with targeted therapies. In this Cell Science at a Glance article and accompanying poster, we highlight the interconnected roles of dysregulated pH dynamics in cancer initiation, progression and adaptation.

Histological Evaluation of Decellularized Skeletal Muscle Tissue Using Two Different Decellularization Agents

The aim of the present study was to determine effect of two decellularized agents, sodium dodecyl sulphate (SDS) and Triton X-100, to the skeletal muscle tissue. Final scaffold was evaluated by several histological techniques to analyse preservation of essential structures including collagen and elastic fibres, basement membranes, glycosaminoglycans and also to confirm elimination of nuclear and cytoplasmic components which are redundant in effectively prepared decellularized scaffolds. Comparison of tissue scaffolds processed with different detergents proved that SDS is superior to Triton X-100 as it can effectively decellularize muscle tissue.

The Metalloprotease Meprin β Is an Alternative β-Secretase of APP

The membrane bound metalloprotease meprin β is important for collagen fibril assembly in connective tissue formation and for the detachment of the intestinal mucus layer for proper barrier function. Recent proteomic studies revealed dozens of putative new substrates of meprin β, including the amyloid precursor protein (APP). It was shown that APP is cleaved by meprin β in distinct ways, either at the β-secretase site resulting in increased levels of Aβ peptides, or at the N-terminus releasing 11 kDa, and 20 kDa peptide fragments. The latter event was discussed to be rather neuroprotective, whereas the ectodomain shedding of APP by meprin β reminiscent to BACE-1 is in line with the amyloid hypothesis of Alzheimer's disease, promoting neurodegeneration. The N-terminal 11 kDa and 20 kDa peptide fragments represent physiological cleavage products, since they are found in human brains under different diseased or non-diseased states, whereas these fragments are completely missing in brains of meprin β knock-out animals. Meprin β is not only a sheddase of adhesion molecules, such as APP, but was additionally demonstrated to cleave within the prodomain of ADAM10. Activated ADAM10, the α-secretase of APP, is then able to shed meprin β from the cell surface thereby abolishing the β-secretase activity. All together meprin β seems to be a novel player in APP processing events, even influencing other enzymes involved in APP cleavage.

TIMPs: versatile extracellular regulators in cancer

A compelling long-term goal of cancer biology is to understand the crucial players during tumorigenesis in order to develop new interventions. Here, we review how the four non-redundant tissue inhibitors of metalloproteinases (TIMPs) regulate the pericellular proteolysis of a vast range of matrix and cell surface proteins, generating simultaneous effects on tumour architecture and cell signalling. Experimental studies demonstrate the contribution of TIMPs to the majority of cancer hallmarks, and human cancers invariably show TIMP deregulation in the tumour or stroma. Of the four TIMPs, TIMP1 overexpression or TIMP3 silencing is consistently associated with cancer progression or poor patient prognosis. Future efforts will align mouse model systems with changes in TIMPs in patients, will delineate protease-independent TIMP function, will pinpoint therapeutic targets within the TIMP-metalloproteinase-substrate network and will use TIMPs in liquid biopsy samples as biomarkers for cancer prognosis.

Claudin-6 enhances cell invasiveness through claudin-1 in AGS human adenocarcinoma gastric cancer cells

Claudins participate in tissue barrier function. The loss of this barrier is associated to metalloproteases-related extracellular matrix and basal membranes degradation. Claudin-1 is a pro-MMP-2 activator and claudin-6 transfected AGS (AGS-Cld6) cells are highly invasive. Our aim was to determine if claudin-6 was direct or indirectly associated with MMP-2 activation and cell invasiveness. Cytofluorometry, cell fractioning, immunoprecipitation, gelatin-zymography, cell migration and invasiveness assays were performed, claudin-2, -6, -7 and -9 transfected AGS cells, anti-MMP-2, -9 and -14, anti-claudins specific antibodies and claudin-1 small interfering RNA were used. The results showed a significant (p<0.001) overexpression of claudin-1 in AGS-Cld6 cell membranes. A strong MMP-2 activity was identified in culture supernatants of AGS-Cld6. Claudin-1 co-localized with MMP-2 and MMP-14; interestingly a significant increase in cell membrane and cytosol MMP-14 expression was detected in AGS-Cld6 cells (p<0.05). Silencing of claudin-1 in AGS-Cld6 cells showed a 60% MMP-2 activity decrease in culture supernatants and a significant decrease (p<0.05) in cell migration and invasiveness. Our results suggest that claudin-6 induces MMP-2 activation through claudin-1 membrane expression, which in turn promotes cell migration and invasiveness.

Cancer-associated fibroblast-secreted CXCL16 attracts monocytes to promote stroma activation in triple-negative breast cancers

Triple-negative (TN) breast cancers (ER⁻PR⁻HER2⁻) are highly metastatic and associated with poor prognosis. Within this subtype, invasive, stroma-rich tumours with infiltration of inflammatory cells are even more aggressive. The effect of myeloid cells on reactive stroma formation in TN breast cancer is largely unknown. Here, we show that primary human monocytes have a survival advantage, proliferate in vivo and develop into immunosuppressive myeloid cells expressing the myeloid-derived suppressor cell marker S100A9 only in a TN breast cancer environment. This results in activation of cancer-associated fibroblasts and expression of CXCL16, which we show to be a monocyte chemoattractant. We propose that this migratory feedback loop amplifies the formation of a reactive stroma, contributing to the aggressive phenotype of TN breast tumours. These insights could help select more suitable therapies targeting the stromal component of these tumours, and could aid prediction of drug resistance.

A reactive tumour stroma is associated with poor prognosis. Here, the authors show that in patients with triple negative breast cancer resident monocytes activate cancer-associated fibroblasts and induce production of CXCL16, which acts as a monocyte chemoattractant, resulting in an amplificatory feedback loop.

Expression and localization of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitors (TIMP-2, -3) in the chicken oviduct during pause in laying induced by tamoxifen

Induced pause in egg laying simulates natural molting events in which the hen's reproductive organs regress and rejuvenate. Such processes require extracellular matrix remodeling that is maintained, at least in part, by the action of proteolytic enzymes known as matrix metalloproteinases (MMPs). Nevertheless, information concerning the expression and hormonal regulation of MMP system members in chickens is scarce. Therefore, MMP-2, -7, and -9 and their tissue inhibitors (TIMP-2, -3) expression and localization were investigated in all segments of the domestic hen oviduct (infundibulum, magnum, isthmus, shell gland, vagina) during a pause in egg laying induced by tamoxifen (TMX)-an estrogen receptor modulator. Hy-Line Brown hens were treated daily with TMX (n = 6) at a dose of 6 mg/kg of body weight or a vehicle (n = 6) until complete cessation of egg laying (for 7 days). Chickens were decapitated on Day 7 of the experiment. Real-time polymerase chain reaction and Western blotting revealed section-dependent expression of MMP-2, -7, -9 and TIMP-2 and -3. Immunohistochemistry found tissue and cell-dependent localization of examined proteins in the wall of the oviduct. The MMP-2, TIMP-2, and TIMP-3 were localized mainly in the luminal epithelium, MMP-7 in the luminal and glandular epithelium, whereas MMP-9 was detected only in the connective tissue. Treatment of chickens with TMX markedly elevated the relative expression of MMP-7 and MMP-9 mRNA in the oviduct, but did not affect MMP-2, TIMP-2, and TIMP-3 mRNA levels. However, TMX increased the MMP-2 protein level in the infundibulum, shell gland, and vagina as well as activity of MMP-2 evaluated by gelatin zymography. The results obtained indicate that MMP-2, MMP-7, and MMP-9 are involved in chicken oviduct regression. Moreover, changes in the expression and activity of chosen MMPs after TMX treatment may indicate a contribution of estrogen in the regulation of transcription, translation, and/or the activity of selected elements of the MMP system.

The multifaceted role of metalloproteinases in physiological and pathological conditions in embryonic and adult brains

Matrix metalloproteinases (MMPs) are a large family of ubiquitous extracellular endopeptidases, which play important roles in a variety of physiological and pathological conditions, from the embryonic stages throughout adult life. Their extraordinary physiological "success" is due to concomitant broad substrate specificities and strict regulation of their expression, activation and inhibition levels. In recent years, MMPs have gained increasing attention as significant effectors in various aspects of central nervous system (CNS) physiology. Most importantly, they have been recognized as main players in a variety of brain disorders having different etiologies and evolution. A common aspect of these pathologies is the development of acute or chronic neuroinflammation. MMPs play an integral part in determining the result of neuroinflammation, in some cases turning its beneficial outcome into a harmful one. This review summarizes the most relevant studies concerning the physiology of MMPs, highlighting their involvement in both the developing and mature CNS, in long-lasting and acute brain diseases and, finally, in nervous system repair. Recently, a concerted effort has been made in identifying therapeutic strategies for major brain diseases by targeting MMP activities. However, from this revision of the literature appears clear that MMPs have multifaceted functional characteristics, which modulate physiological processes in multiple ways and with multiple consequences. Therefore, when choosing MMPs as possible targets, great care must be taken to evaluate the delicate balance between their activation and inhibition and to determine at which stage of the disease and at what level they become active in order maximize chances of success.