Thrombin induces tumor invasion through the induction and association of matrix metalloproteinase-9 and beta1-integrin on the cell surface

Inhibitory effect of recombinant tyrosine‑sulfated madanin‑1, a thrombin inhibitor, on the behavior of MDA‑MB‑231 and SKOV3 cells in vitro

Thrombin, which plays a crucial role in hemostasis, is also implicated in cancer progression. In the present study, the effects of the thrombin‑targeting recombinant tyrosine‑sulfated madanin‑1 on cancer cell behavior and signaling pathways compared with madanin‑1 wild‑type (WT) were investigated. Recombinant madanin‑1 2 sulfation (madanin‑1 2S) and madanin‑1 WT proteins were generated using Escherichia coli. SKOV3 and MDA‑MB‑231 cells were treated with purified recombinant proteins with or without thrombin stimulation. Migration and invasion of cells were analyzed by wound healing assay and Transwell assay, respectively. Thrombin markedly increased cell migration and invasion in both SKOV3 and MDA‑MB‑231 cells, which were significantly suppressed by madanin‑1 2S (P<0.05). Madanin‑1 2S also significantly suppressed thrombin‑induced expression of phosphorylated (p)‑Akt and p‑extracellular signal‑regulated kinase in both cell lines (P<0.05), whereas madanin‑1 WT had no effect on the expression levels of these proteins in MDA‑MB‑231 cells. Furthermore, madanin‑1 2S significantly reversed the effects of thrombin on E‑cadherin, N‑cadherin and vimentin expression in MDA‑MB‑231 cells (P<0.05), whereas madanin‑1 WT did not show any effect. In conclusion, madanin‑1 2S suppressed the migration and invasion of cancer cells more effectively than madanin‑1 WT. It is hypothesized that inhibiting thrombin via the sulfated form of madanin‑1 may be a potential candidate for enhanced cancer therapy; however, further in vivo validation is required.

The Complex Role of Thrombin in Cancer and Metastasis: Focus on Interactions with the Immune System

Thrombin, a pleiotropic enzyme involved in coagulation, plays a crucial role in both procoagulant and anticoagulant pathways. Thrombin converts fibrinogen into fibrin, initiates platelet activation, and promotes clot formation. Thrombin also activates anticoagulant pathways, indirectly inhibiting factors involved in coagulation. Tissue factor triggers thrombin generation, and the overexpression of thrombin in various cancers suggests that it is involved in tumor growth, angiogenesis, and metastasis. Increased thrombin generation has been observed in cancer patients, especially those with metastases. Thrombin exerts its effects through protease-activated receptors (PARs), particularly PAR-1 and PAR-2, which are involved in cancer progression, angiogenesis, and immunological responses. Thrombin-mediated signaling promotes angiogenesis by activating endothelial cells and platelets, thereby releasing proangiogenic factors. These functions of thrombin are well recognized and have been widely described. However, in recent years, intriguing new findings concerning the association between thrombin activity and cancer development have come to light, which justifies a review of this research. In particular, there is evidence that thrombin-mediated events interact with the immune system, and may regulate its response to tumor growth. It is also worth reevaluating the impact of thrombin on thrombocytes in conjunction with its multifaceted influence on tumor progression. Understanding the role of thrombin/PAR-mediated signaling in cancer and immunological responses is crucial, particularly in the context of developing immunotherapies. In this systematic review, we focus on the impact of the thrombin-related immune system response on cancer progression.

Cleavage of periostin by MMP9 protects mice from kidney cystic disease

The matrix metalloproteinase MMP9 influences cellular morphology and function, and plays important roles in organogenesis and disease. It exerts both protective and deleterious effects in renal pathology, depending upon its specific substrates. To explore new functions for MMP9 in kidney cysts formation and disease progression, we generated a mouse model by breeding juvenile cystic kidney (jck) mice with MMP9 deficient mice. Specifically, we provide evidence that MMP9 is overexpressed in cystic tissue where its enzymatic activity is increased 7-fold. MMP9 deficiency in cystic kidney worsen cystic kidney diseases by decreasing renal function, favoring cyst expansion and fibrosis. In addition, we find that periostin is a new critical substrate for MMP9 and in its absence periostin accumulates in cystic lining cells. As periostin promotes renal cyst growth and interstitial fibrosis in polycystic kidney diseases, we propose that the control of periostin by MMP9 and its associated intracellular signaling pathways including integrins, integrin-linked kinase and focal adhesion kinase confers to MMP9 a protective effect on the severity of the disease.

Unraveling the Role of Hydrogen Bonds in Thrombin via Two Machine Learning Methods

Hydrogen bonds play a critical role in the folding and stability of proteins, such as proteins and nucleic acids, by providing strong and directional interactions. They help to maintain the secondary and 3D structure of proteins, and structural changes in these molecules often result from the formation or breaking of hydrogen bonds. To gain insights into these hydrogen bonding networks, we applied two machine learning models - a logistic regression model and a decision tree model - to study four variants of thrombin: wild-type, ΔK9, E8K, and R4A. Our results showed that both models have their unique advantages. The logistic regression model highlighted potential key residues (GLU295) in thrombin's allosteric pathways, while the decision tree model identified important hydrogen bonding motifs. This information can aid in understanding the mechanisms of folding in proteins and has potential applications in drug design and other therapies. The use of these two models highlights their usefulness in studying hydrogen bonding networks in proteins.

MLL regulates the actin cytoskeleton and cell migration by stabilising Rho GTPases via the expression of RhoGDI1

Attainment of proper cell shape and the regulation of cell migration are essential processes in the development of an organism. The mixed lineage leukemia (MLL or KMT2A) protein, a histone 3 lysine 4 (H3K4) methyltransferase, plays a critical role in cell-fate decisions during skeletal development and haematopoiesis in higher vertebrates. Rho GTPases - RhoA, Rac1 and CDC42 - are small G proteins that regulate various key cellular processes, such as actin cytoskeleton formation, the maintenance of cell shape and cell migration. Here, we report that MLL regulates the homeostasis of these small Rho GTPases. Loss of MLL resulted in an abnormal cell shape and a disrupted actin cytoskeleton, which lead to diminished cell spreading and migration. MLL depletion affected the stability and activity of Rho GTPases in a SET domain-dependent manner, but these Rho GTPases were not direct transcriptional targets of MLL. Instead, MLL regulated the transcript levels of their chaperone protein RhoGDI1 (also known as ARHGDIA). Using MDA-MB-231, a triple-negative breast cancer cell line with high RhoGDI1 expression, we show that MLL depletion or inhibition by small molecules reduces tumour progression in nude mice. Our studies highlight the central regulatory role of MLL in Rho/Rac/CDC42 signalling pathways. This article has an associated First Person interview with the first author of the paper.

Association of anticoagulant use with clinical outcomes from crizotinib in ALK- and ROS1-rearranged advanced non-small cell lung cancers: A retrospective analysis of PROFILE 1001

BACKGROUND

ROS1- and ALK-rearranged advanced NSCLCs are associated with increased thromboembolic risk. We hypothesized that a prothrombotic phenotype offers an evolutionary advantage to subsets of these cancers. The impact of this phenotype could alter outcomes from targeted therapy.

METHODS

In a retrospective analysis of ROS1- and ALK-rearranged NSCLCs treated with crizotinib in a phase 1 trial, we compared progression-free survival (PFS) and objective response rate (ORR) based on the history of anticoagulation use (a possible surrogate of thromboembolism) at baseline (within 90 days before study enrollment) or within 90 days of study treatment.

RESULTS

Twelve out of 53 (22.6%) ROS1- and 39 out of 153 (25.5%) ALK-rearranged NSCLCs received anticoagulation before or during the trial. Most ROS1 and ALK patients on anticoagulation received low-molecular-weight heparin (75% and 64.1%, respectively). In the ROS1-rearranged group, the median PFS (95% CI) values were 5.1 (4.4-14.4) and 29.0 (16.5-48.8) months, and the ORR values were 41.7% (95% CI: 15.2 to 72.3) and 80.5% (95% CI: 65.1 to 91.2) among those with and without anticoagulation treatment, respectively. In the ALK-rearranged group, the median PFS (95% CI) was 7.1 (5.4-7.7) and 12.0 (9.4-18.3) months, and the ORR was 41% (95% CI: 25.6 to 57.9) and 74.3% (95% CI: 65.3 to 82.1) among those with and without anticoagulation, respectively.

CONCLUSIONS

Anticoagulation (as a potential surrogate of a prothrombotic subset) in ROS1- and ALK-rearranged NSCLCs may be associated with a lower PFS and ORR to crizotinib.

CLINICALTRIAL

gov: NCT00585195.

Antiplatelet Agents Affecting GPCR Signaling Implicated in Tumor Metastasis

Metastasis requires that cancer cells survive in the circulation, colonize distant organs, and grow. Despite platelets being central contributors to hemostasis, leukocyte trafficking during inflammation, and vessel stability maintenance, there is significant evidence to support their essential role in supporting metastasis through different mechanisms. In addition to their direct interaction with cancer cells, thus forming heteroaggregates such as leukocytes, platelets release molecules that are necessary to promote a disseminating phenotype in cancer cells via the induction of an epithelial-mesenchymal-like transition. Therefore, agents that affect platelet activation can potentially restrain these prometastatic mechanisms. Although the primary adhesion of platelets to cancer cells is mainly independent of G protein-mediated signaling, soluble mediators released from platelets, such as ADP, thromboxane (TX) A2, and prostaglandin (PG) E2, act through G protein-coupled receptors (GPCRs) to cause the activation of more additional platelets and drive metastatic signaling pathways in cancer cells. In this review, we examine the contribution of the GPCRs of platelets and cancer cells in the development of cancer metastasis. Finally, the possible use of agents affecting GPCR signaling pathways as antimetastatic agents is discussed.

CD44 modulates metabolic pathways and altered ROS-mediated Akt signal promoting cholangiocarcinoma progression

CD44 is a transmembrane glycoprotein, the phosphorylation of which can directly trigger intracellular signaling, particularly Akt protein, for supporting cell growth, motility and invasion. This study examined the role of CD44 on the progression of Cholangiocarcinoma (CCA) using metabolic profiling to investigate the molecular mechanisms involved in the Akt signaling pathway. Our results show that the silencing of CD44 decreases Akt and mTOR phosphorylation resulting in p21 and Bax accumulation and Bcl-2 suppression that reduces cell proliferation. Moreover, an inhibition of cell migration and invasion regulated by CD44. Similarly, the silencing of CD44 showed an alteration in the epithelial-mesenchymal transition (EMT), e.g. an upregulation of E-cadherin and a downregulation of vimentin, and the reduction of the matrix metalloproteinase (MMP)-9 signal. Interestingly, a depletion of CD44 leads to metabolic pathway changes resulting in redox status modification and Trolox (anti-oxidant) led to the recovery of the cancer cell functions. Based on our findings, the regulation of CCA progression and metastasis via the redox status-related Akt signaling pathway depends on the alteration of metabolic profiling synchronized by CD44.

Light Chain Mutation Effects on the Dynamics of Thrombin

Thrombin plays an important role in the process of hemostasis and blood coagulation. Studies in thrombin can help us find ways to treat cancer because thrombin is able to reduce the characteristic hypercoagulability of cancer. Thrombin is composed of two chains, the light chain and the heavy chain. The function of the heavy chain has been largely explored, while the function of the light chain was obscured until several disease-associated mutations in the light chain come to light. In this study, we want to explore the dynamic and conformation effects of mutations on the light chain further to determine possible associations between mutation, conformational changes, and disease. The study, which is a follow-up for our studies on apo thrombin and the mutant, ΔK9, mainly focuses on the mutants E8K and R4A. E8K is a disease-associated mutation, and R4A is used to study the role of Arg4, which is suggested experimentally to play a critical role for thrombin's catalytic activities. We performed five all-atom one microsecond-scale molecular dynamics (MD) simulations for both E8K and R4A, and quantified the changes in the conformational ensemble of the mutants. From the root-mean-square fluctuations (RMSF) for the α-carbons, we find that the atomic fluctuations change in the mutants in the 60s loop and γ loop. The correlation coefficients for the α-carbons indicate that the correlation relation for atom-pairs in the protein is also impacted. The clustering analysis and the principal component analysis (PCA) consistently tell us that the catalytic pocket and the regulatory loops are destabilized by the mutations. We also find that there are two binding modes for Na⁺ by clustering the vector difference between the Na⁺ ions and the 220s loop. After further analysis, we find that there is a relation between the Na⁺ binding and the rigidification of the γ loop, which may shed light on the mysterious role of the γ loop in thrombin.

MALT1 is a critical mediator of PAR1-driven NF-κB activation and metastasis in multiple tumor types

Protease-activated receptor 1 (PAR1), a thrombin-responsive G protein-coupled receptor (GPCR), is implicated in promoting metastasis in multiple tumor types, including both sarcomas and carcinomas, but the molecular mechanisms responsible remain largely unknown. We previously discovered that PAR1 stimulation in endothelial cells leads to activation of NF-κB, mediated by a protein complex comprised of CARMA3, Bcl10, and the MALT1 effector protein (CBM complex). Given the strong association between NF-κB and metastasis, we hypothesized that this CBM complex could play a critical role in the PAR1-driven metastatic progression of specific solid tumors. In support of our hypothesis, we demonstrate that PAR1 stimulation results in NF-κB activation in both osteosarcoma and breast cancer, which is suppressed by siRNA-mediated MALT1 knockdown, suggesting that an intact CBM complex is required for the response in both tumor cell types. We identify several metastasis-associated genes that are upregulated in a MALT1-dependent manner after PAR1 stimulation in cancer cells, including those encoding the matrix remodeling protein, MMP9, and the cytokines, IL-1β and IL-8. Further, exogenous expression of PAR1 in MCF7 breast cancer cells confers highly invasive and metastatic behavior which can be blocked by CRISPR/Cas9-mediated MALT1 knockout. Importantly, we find that PAR1 stimulation induces MALT1 protease activity in both osteosarcoma and breast cancer cells, an activity that is mechanistically linked to NF-κB activation and potentially other responses associated with aggressive phenotype. Several small molecule MALT1 protease inhibitors have recently been described that could therefore represent promising new therapeutics for the prevention and/or treatment of PAR1-driven tumor metastasis.

Probing light chain mutation effects on thrombin via molecular dynamics simulations and machine learning

Thrombin is a key component for chemotherapeutic and antithrombotic therapy development. As the physiologic and pathologic roles of the light chain still remain vague, here, we continue previous efforts to understand the impacts of the disease-associated single deletion of LYS9 in the light chain. By combining supervised and unsupervised machine learning methodologies and more traditional structural analyses on data from 10 μs molecular dynamics simulations, we show that the conformational ensemble of the ΔK9 mutant is significantly perturbed. Our analyses consistently indicate that LYS9 deletion destabilizes both the catalytic cleft and regulatory functional regions and result in some conformational changes that occur in tens to hundreds of nanosecond scaled motions. We also reveal that the two forms of thrombin each prefer a distinct binding mode of a Na+ ion. We expand our understanding of previous experimental observations and shed light on the mechanisms of the LYS9 deletion associated bleeding disorder by providing consistent but more quantitative and detailed structural analyses than early studies in literature. With a novel application of supervised learning, i.e. the decision tree learning on the hydrogen bonding features in the wild-type and ΔK9 mutant forms of thrombin, we predict that seven pairs of critical hydrogen bonding interactions are significant for establishing distinct behaviors of wild-type thrombin and its ΔK9 mutant form. Our calculations indicate the LYS9 in the light chain has both localized and long-range allosteric effects on thrombin, supporting the opinion that light chain has an important role as an allosteric effector.

Na+-binding modes involved in thrombin's allosteric response as revealed by molecular dynamics simulations, correlation networks and Markov modeling

The monovalent sodium ion (Na+) is a critical modulator of thrombin. However, the mechanism of thrombin's activation by Na+ has been widely debated for more than twenty years. Details of the linkage between thrombin and Na+ remain vague due to limited temporal and spatial resolution in experiments. In this work, we combine microsecond scale atomic-detailed molecular dynamics simulations with correlation network analyses and hidden Markov modeling to probe the detailed thermodynamic and kinetic picture of Na+-binding events and their resulting allosteric responses in thrombin. We reveal that ASP189 and ALA190 comprise a stable Na+-binding site (referred as "inner" Na+-binding site) along with the previously known one (referred as "outer" Na+-binding site). The corresponding newly identified Na+-binding mode introduces significant allosteric responses in thrombin's regulatory regions by stabilizing selected torsion angles of residues responsive to Na+-binding. Our Markov model indicates that the bound Na+ prefers to transfer between the two Na+-binding sites when an unbinding event takes place. These results suggest a testable hypothesis of a substrate-driven Na+ migration (ΔG ∼ 1.7 kcal mol-1) from the "inner" Na+-binding site to the "outer" one during thrombin's catalytic activities. The binding of a Na+ ion at the "inner" Na+-binding site should be inferred as a prerequisite for thrombin's efficient recognition to the substrate, which opens a new angle for our understanding of Na+-binding's allosteric activation on thrombin and sheds light on detailed processes in thrombin's activation.

Monoclonal Antibody Targeting the Matrix Metalloproteinase 9 Prevents and Reverses Paclitaxel-Induced Peripheral Neuropathy in Mice

Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling condition accompanying several cancer drugs, including the front-line chemotherapeutic agent paclitaxel. Although CIPN can force dose reduction or even discontinuation of chemotherapy, affecting survival in cancer patients, there is no US Food and Drug Administration-approved treatment for CIPN. CIPN in mice is characterized by neuropathic pain (eg, mechanical allodynia) in association with oxidative stress and neuroinflammation in dorsal root ganglia (DRGs), as well as retraction of intraepidermal nerve fibers. Here, we report that paclitaxel-induced mechanical allodynia is associated with transcriptional increase in matrix metalloproteinase (MMP) 2 and 9 and decrease in metallopeptidase inhibitor 1 (TIMP1), a strong endogenous MMP9 inhibitor. Consistently, MMP9 protein levels are increased in DRG neurons in vivo and in vitro after paclitaxel treatment, and it is demonstrated, for the first time, that intrathecal injections of exogenous TIMP1 or a monoclonal antibody targeting MMP9 (MMP9 mAb) significantly prevented and reversed paclitaxel-induced mechanical allodynia in male and female mice. Analyses of DRG tissues showed that MMP9 mAb significantly decreased oxidative stress and neuroinflammatory mediators interleukin-6 and tumor necrosis factor α, as well as prevented paclitaxel-induced loss of intraepidermal nerve fibers. These findings suggest that MMP signaling plays a key role in paclitaxel-induced peripheral neuropathy, and MMP9 mAb may offer new therapeutic approaches for the treatment of CIPN. PERSPECTIVE: Chemotherapy-induced peripheral neuropathy (CIPN) remains ineffectively managed in cancer patients, potentially leading to the discontinuation of an otherwise life-saving treatment. Here, we demonstrate that a monoclonal antibody targeting MMP9 alleviates neuropathic pain and several mechanisms linked to CIPN. This study is particularly relevant, because a humanized MMP9 antibody is already in advanced clinical trials for the treatment of colitis and cancer, and it may be straightforwardly repurposed for the relief of CIPN.

Protease-activated receptor 1 activation enhances doxorubicin-induced cardiotoxicity

OBJECTIVE

The anti-cancer anthracycline drug Doxorubicin (Dox) causes cardiotoxicity. We investigated the role of protease-activated receptor 1 (PAR-1) in Dox-induced cardiotoxicity.

METHODS AND RESULTS

In vitro experiments revealed that PAR-1 enhanced Dox-induced mitochondrial dysfunction, reactive oxygen species and cell death of cardiac myocytes and cardiac fibroblasts. The contribution of PAR-1 to Dox-induced cardiotoxicity was investigated by subjecting PAR-1^-/- mice and PAR-1^+/+ mice to acute and chronic exposure to Dox. Heart function was measured by echocardiography. PAR-1^-/- mice exhibited significant less cardiac injury and dysfunction compared to PAR-1^+/+ mice after acute and chronic Dox administration. PAR-1^-/- mice had reduced levels of nitrotyrosine, apoptosis and inflammation in their heart compared to PAR-1^+/+ mice. Furthermore, inhibition of PAR-1 in wild-type mice with vorapaxar significantly reduced the acute Dox-induced cardiotoxicity.

CONCLUSION

Our results indicate that activation of PAR-1 contributes to Dox-induced cardiotoxicity. Inhibition of PAR-1 may be a new approach to reduce Dox-induced cardiotoxicity in cancer patients.

Platelet-targeted pharmacologic treatments as anti-cancer therapy

Platelets act as multifunctional cells participating in immune response, inflammation, allergy, tissue regeneration, and lymphoangiogenesis. Among the best-established aspects of a role of platelets in non-hemostatic or thrombotic disorders, there is their participation in cancer invasion and metastasis. The interaction of many different cancer cells with platelets leads to platelet activation, and on the other hand platelet activation is strongly instrumental to the pro-carcinogenic and pro-metastatic activities of platelets. It is thus obvious that over the last years a lot of interest has focused on the possible chemopreventive effect of platelet-targeted pharmacologic treatments. This article gives an overview of the platelet-targeted pharmacologic approaches that have been attempted in the prevention of cancer development, progression, and metastasis, including the application of anti-platelet drugs currently used for cardiovascular disease and of new and novel pharmacologic strategies. Despite the fact that very promising results have been obtained with some of these approaches in pre-clinical models, with the exclusion of aspirin, clinical evidence of a beneficial effect of anti-platelet agents in cancer is however still largely missing. Future studies with platelet-targeted drugs in cancer must carefully deal with design issues, and in particular with the careful selection of patients, and/or explore novel platelet targets in order to provide a solution to the critical issue of the risk/benefit profile of long-term anti-platelet therapy in the prevention of cancer progression and dissemination.

The α-arrestin ARRDC3 suppresses breast carcinoma invasion by regulating G protein-coupled receptor lysosomal sorting and signaling

Aberrant G protein-coupled receptor (GPCR) expression and activation has been linked to tumor initiation, progression, invasion, and metastasis. However, compared with other cancer drivers, the exploitation of GPCRs as potential therapeutic targets has been largely ignored, despite the fact that GPCRs are highly druggable. Therefore, to advance the potential status of GPCRs as therapeutic targets, it is important to understand how GPCRs function together with other cancer drivers during tumor progression. We now report that the α-arrestin domain-containing protein-3 (ARRDC3) acts as a tumor suppressor in part by controlling signaling and trafficking of the GPCR, protease-activated receptor-1 (PAR1). In a series of highly invasive basal-like breast carcinomas, we found that expression of ARRDC3 is suppressed whereas PAR1 is aberrantly overexpressed because of defective lysosomal sorting that results in persistent signaling. Using a lentiviral doxycycline-inducible system, we demonstrate that re-expression of ARRDC3 in invasive breast carcinoma is sufficient to restore normal PAR1 trafficking through the ALG-interacting protein X (ALIX)-dependent lysosomal degradative pathway. We also show that ARRDC3 re-expression attenuates PAR1-stimulated persistent signaling of c-Jun N-terminal kinase (JNK) in invasive breast cancer. Remarkably, restoration of ARRDC3 expression significantly reduced activated PAR1-induced breast carcinoma invasion, which was also dependent on JNK signaling. These findings are the first to identify a critical link between the tumor suppressor ARRDC3 and regulation of GPCR trafficking and signaling in breast cancer.

Visualizing correlated motion with HDBSCAN clustering

Correlated motion analysis provides a method for understanding communication between and dynamic similarities of biopolymer residues and domains. The typical equal-time correlation matrices-frequently visualized with pseudo-colorings or heat maps-quickly convey large regions of highly correlated motion but hide more subtle similarities of motion. Here we propose a complementary method for visualizing correlations within proteins (or general biopolymers) that quickly conveys intuition about which residues have a similar dynamic behavior. For grouping residues, we use the recently developed non-parametric clustering algorithm HDBSCAN. Although the method we propose here can be used to group residues using correlation as a similarity matrix-the most straightforward and intuitive method-it can also be used to more generally determine groups of residues which have similar dynamic properties. We term these latter groups "Dynamic Domains", as they are based not on spatial closeness but rather closeness in the column space of a correlation matrix. We provide examples of this method across three human proteins of varying size and function-the Nf-Kappa-Beta essential modulator, the clotting promoter Thrombin and the mismatch repair protein (dimer) complex MutS-alpha. Although the examples presented here are from all-atom molecular dynamics simulations, this visualization technique can also be used on correlations matrices built from any ensembles of conformations from experiment or computation.

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.

Molecular dynamics simulations of aptamer-binding reveal generalized allostery in thrombin

Thrombin is an attractive target for antithrombotic therapy due to its central role in thrombosis and hemostasis as well as its role in inducing tumor growth, metastasis, and tumor invasion. The thrombin-binding DNA aptamer (TBA), is under investigation for anticoagulant drugs. Although aptamer binding experiments have been revealed various effects on thrombin's enzymatic activities, the detailed picture of the thrombin's allostery from TBA binding is still unclear. To investigate thrombin's response to the aptamer-binding at the molecular level, we compare the mechanical properties and free energy landscapes of the free and aptamer-bound thrombin using microsecond-scale all-atom GPU-based molecular dynamics simulations. Our calculations on residue fluctuations and coupling illustrate the allosteric effects of aptamer-binding at the atomic level, highlighting the exosite II, 60s, γ and the sodium loops, and the alpha helix region in the light chains involved in the allosteric changes. This level of details clarifies the mechanisms of previous experimentally demonstrated phenomena, and provides a prediction of the reduced autolysis rate after aptamer-binding. The shifts in thrombin's ensemble of conformations and free energy surfaces after aptamer-binding demonstrate that the presence of bound-aptamer restricts the conformational freedom of thrombin suggesting that conformational selection, i.e. generalized allostery, is the dominant mechanism of thrombin-aptamer binding. The profound perturbation on thrombin's mechanical and thermodynamic properties due to the aptamer-binding, which was revealed comprehensively as a generalized allostery in this work, may be exploited in further drug discovery and development.

Mechanistic insights into thrombin's switch between "slow" and "fast" forms

Thrombin is a multifunctional enzyme that plays an important role in blood coagulation, cell growth, and metastasis. Depending upon the binding of sodium ions, thrombin presents significantly different enzymatic activities. In the environment with sodium ions, thrombin is highly active in cleaving the coagulated substrates and this is referred to as the "fast" form; in the environment without sodium ions, thrombin turns catalytically less active and is in the "slow" form. Although many experimental studies over the last two decades have attempted to reveal the structural and kinetic differences between these two forms, it remains vague and disputed how the functional switch between the "fast" and "slow" forms is mediated by Na+ cations. In this work, we employ microsecond-scale all-atom molecular dynamics simulations to investigate the differences in the structural ensembles in sodium-bound/unbound and potassium-bound/unbound thrombin. Our calculations indicate that the regulatory regions, including the 60s, γ loops, and exosite I and II, are primarily affected by both the bound and unbound cations. Conformational free energy surfaces, estimated from principal component analysis, further reveal the existence of multiple conformational states. The binding of a cation introduces changes in the distribution of these states. Through comparisons with potassium-binding, the binding of sodium ions appears to shift the population toward conformational states that might be catalytically favorable. Our study of thrombin in the presence of sodium/potassium ions suggests Na+-mediated generalized allostery is the mechanism of thrombin's functional switch between the "fast" and "slow" forms.

A loop of cancer-stroma-cancer interaction promotes peritoneal metastasis of ovarian cancer via TNFα-TGFα-EGFR

Peritoneum is the most common site for ovarian cancer metastasis. Here we investigate how cancer epigenetics regulates reciprocal tumor-stromal interactions in peritoneal metastasis of ovarian cancer. Firstly, we find that omental stromal fibroblasts enhance colony formation of metastatic ovarian cancer cells, and de novo expression of transforming growth factor-alpha (TGF-α) is induced in stromal fibroblasts co-cultured with ovarian cancer cells. We also observed an over-expression of tumor necrosis factor-alpha (TNF-α) in ovarian cancer cells, which is regulated by promoter DNA hypomethylation as well as chromatin remodeling. Interestingly, this ovarian cancer-derived TNF-α induces TGF-α transcription in stromal fibroblasts through nuclear factor-κB (NF-κB). We further show that TGF-α secreted by stromal fibroblasts in turn promotes peritoneal metastasis of ovarian cancer through epidermal growth factor receptor (EGFR) signaling. Finally, we identify a TNFα-TGFα-EGFR interacting loop between tumor and stromal compartments of human omental metastases. Our results therefore demonstrate cancer epigenetics induces a loop of cancer-stroma-cancer interaction in omental microenvironment that promotes peritoneal metastasis of ovarian cancer cells via TNFα-TGFα-EGFR.

Thrombin-unique coagulation system protein with multifaceted impacts on cancer and metastasis

The association between blood coagulation and cancer development is well recognized. Thrombin, the pleiotropic enzyme best known for its contribution to fibrin formation and platelet aggregation during vascular hemostasis, may also trigger cellular events through protease-activated receptors, PAR-1 and PAR-4, leading to cancer progression. Our pioneering findings provided evidence that thrombin contributes to cancer metastasis by increasing adhesive potential of malignant cells. However, there is evidence that thrombin regulates every step of cancer dissemination: (1) cancer cell invasion, detachment from primary tumor, migration; (2) entering the blood vessel; (3) surviving in vasculature; (4) extravasation; (5) implantation in host organs. Recent studies have provided new molecular data about thrombin generation in cancer patients and the mechanisms by which thrombin contributes to transendothelial migration, platelet/tumor cell interactions, angiogenesis, and other processes. Though a great deal is known regarding the role of thrombin in cancer dissemination, there are new data for multiple thrombin-mediated events that justify devoting focus to this topic with a comprehensive approach.

Activated tumor cell integrin αvβ3 cooperates with platelets to promote extravasation and metastasis from the blood stream

Metastasis is the main cause of death in cancer patients, and understanding mechanisms that control tumor cell dissemination may lead to improved therapy. Tumor cell adhesion receptors contribute to cancer spreading. We noted earlier that tumor cells can expressing the adhesion receptor integrin αvβ3 in distinct states of activation, and found that cells which metastasize from the blood stream express it in a constitutively high affinity form. Here, we analyzed steps of the metastatic cascade in vivo and asked, when and how the affinity state of integrin αvβ3 confers a critical advantage to cancer spreading. Following tumor cells by real time PCR, non-invasive bioluminescence imaging, intravital microscopy and histology allowed us to identify tumor cell extravasation from the blood stream as a rate-limiting step supported by high affinity αvβ3. Successful transendothelial migration depended on cooperation between tumor cells and platelets involving the high affinity tumor cell integrin and release of platelet granules. Thus, this study identifies the high affinity conformer of integrin αvβ3 and its interaction with platelets as critical for early steps during hematogenous metastasis and target for prevention of metastatic disease.

Uncovering Large-Scale Conformational Change in Molecular Dynamics without Prior Knowledge

As the length of molecular dynamics (MD) trajectories grows with increasing computational power, so does the importance of clustering methods for partitioning trajectories into conformational bins. Of the methods available, the vast majority require users to either have some a priori knowledge about the system to be clustered or to tune clustering parameters through trial and error. Here we present non-parametric uses of two modern clustering techniques suitable for first-pass investigation of an MD trajectory. Being non-parametric, these methods require neither prior knowledge nor parameter tuning. The first method, HDBSCAN, is fast-relative to other popular clustering methods-and is able to group unstructured or intrinsically disordered systems (such as intrinsically disordered proteins, or IDPs) into bins that represent global conformational shifts. HDBSCAN is also useful for determining the overall stability of a system-as it tends to group stable systems into one or two bins-and identifying transition events between metastable states. The second method, iMWK-Means, with explicit rescaling followed by K-Means, while slower than HDBSCAN, performs well with stable, structured systems such as folded proteins and is able to identify higher resolution details such as changes in relative position of secondary structural elements. Used in conjunction, these clustering methods allow a user to discern quickly and without prior knowledge the stability of a simulated system and identify both local and global conformational changes.

Prognostic value of plasma D-dimer levels in patients with small-cell lung cancer

OBJECTIVE

Little data exists with respect to the relationship between the level of plasma D-dimer and prognosis of small cell lung cancer (SCLC).The aim of this study was to investigate whether the levels of plasma D-dimer could be served as a prognostic factor in patients with SCLC.

METHODS

A total of 393 patients with SCLC were addressed in the present retrospective study. Plasma D-dimer levels were measured by immunoturbidimetric assay. The correlation between plasma D-dimer levels and other clinical features, progression free survival (PFS) and overall survival (OS) was analyzed statistically.

RESULTS

The plasma D-dimer levels were significantly correlated with karnofsky performance status (KPS), tumor stage, number of metastatic sites, and treatment response. The PFS and OS of patients with elevated D-dimer levels before chemotherapy were significantly shorter than that of patients with normal D-dimer levels (PFS: 6.2 months versus 9.6 months, P<0.001; OS: 15.7 months versus 24.4 months, P<0.001). The patients with D-dimer levels converting from high to normal had better PFS and OS than those with D-dimer levels remaining high after two cycles of chemotherapy. According to multivariate analysis, elevated D-dimer level was confirmed to be an independent prognostic factor for worse survival.

CONCLUSIONS

Elevated plasma D-dimer level could be served as an independent determinant of poor prognosis in patients with SCLC.

Downregulation of Integrins in Cancer Cells and Anti-Platelet Properties Are Involved in Holothurian Glycosaminoglycan-Mediated Disruption of the Interaction of Cancer Cells and Platelets in Hematogenous Metastasis

Activated platelets have been recognized as an accessory character in the cascade of tumor hematogenous metastasis, and intervention of tumor cell attachment to the activated platelets or microemboli formation might be a leading strategy to prevent tumor cells surviving in the blood vessels and sequential metastasis. Recently, we have demonstrated that holothurian glycosaminoglycan (hGAG), a sulfated polysaccharide with potent anticoagulant activity extracted from the sea cucumber Holothuria leucospilota Brandt, was highly efficacious against tumor metastasis. In this study, we identified the potential effects of hGAG on the disruption of interactions of cancer cells and platelets and the underlying mechanisms, which were supported by the following evidence: hGAG (1) inhibited thrombin-induced platelet activation and aggregation, (2) reduced adhesion between platelet and breast cancer cells, and abrogated platelets/cancer cells adhering to fibrinogen, (3) attenuated platelet-cancer cell complex formation (the number and size of aggregates) and (4) suppressed both mRNA and protein levels of β1 and β3 integrins, matrix metalloproteinase (MMP)-2 and MMP-9, while increasing the expression of the MMP inhibitor, tissue inhibitor of metalloproteinase (TIMP)-1 in MDA-MB-231 cells. These results suggested that both the antiplatelet properties and mitigation of the levels of cellular adhesion molecules contributed to the anticancer effects of hGAG, and might thus be exploited for clinical adjuvant therapy to attenuate tumor hematogenous metastasis.

Quantitative urinary proteomics using stable isotope labelling by peptide dimethylation in patients with prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed malignancy in men. The current prevalent diagnosis method, prostate-specific antigen (PSA) screening test, has low sensitivity, specificity and is poor at predicting the grade of disease. Thus, new biomarkers are urgently needed to improve the PCa diagnosis and staging for the management of patients. The aim of this study is to investigate the first voided urinary sample after massage for biomarker discovery for PCa. In this work, untargeted metabolomic profiling of the first voided urinary sample after massage from 28 confirmed prostate cancer patients, 20 benign enlarged prostate patients and 6 healthy volunteers was performed using liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-MS/MS). Single and multiple peptide protein and cross-linking molecules were identified using PEAKS software. Analytical and diagnostic performance was tested using the Student's t test, Benjamini Hochberg correction and the receiver operating characteristic (ROC) curves. Using differential display analysis to compare peptides and cross-linking molecules of urinary samples between patients with benign, enlarged prostate and malignant cancer, we identified multiple peptides derived from osteopontin (SPP1) and prothrombin (F2) that are lower in PCa patients than in benign and enlarged prostate. The diagnosis accuracies of SPP1 and F2 peptides are 0.65-0.77 and 0.68-0.72, respectively. In addition to this, there are significant differences between PCa and benign/enlarged prostate patients in pyridinoline (PYD) and deoxypyridinoline (DPD) (p value = 0.001). Differences also, as shown in the excretion of these molecules for different stages of PCa (p value = 0.04) as the level of DPD and DPD/PYD ratio, were high in patients with locally advanced tumours. The study underscores the importance of proteomics analysis, and our results demonstrate that a urinary-based in depth proteomic approach allows the potential identification of dysregulated pathways and diagnostic biomarkers.

Coagulation and angiogenic gene expression profiles are defined by molecular subgroups of medulloblastoma: evidence for growth factor-thrombin cross-talk

BACKGROUND

The coagulation system becomes activated during progression and therapy of high-grade brain tumors. Triggering tissue factor (F3/TF) and thrombin receptors (F2R/PAR-1) may influence the vascular tumor microenvironment and angiogenesis irrespective of clinically apparent thrombosis. These processes are poorly understood in medulloblastoma (MB), in which diverse oncogenic pathways define at least four molecular disease subtypes (WNT, SHH, Group 3 and Group 4). We asked whether there is a link between molecular subtype and the network of vascular regulators expressed in MB.

METHODS

Using R2 microarray analysis and visualization platform, we mined MB datasets for differential expression of vascular (coagulation and angiogenesis)-related genes, and explored their link to known oncogenic drivers. We evaluated the functional significance of this link in DAOY cells in vitro following growth factor and thrombin stimulation.

RESULTS

The coagulome and angiome differ across MB subtypes. F3/TF and F2R/PAR-1 mRNA expression are upregulated in SHH tumors and correlate with higher levels of hepatocyte growth factor receptor (MET). Cultured DAOY (MB) cells exhibit an up-regulation of F3/TF and F2R/PAR-1 following combined SHH and MET ligand (HGF) treatment. These factors cooperate with thrombin, impacting the profile of vascular regulators, including interleukin 1β (IL1B) and chondromodulin 1 (LECT1).

CONCLUSIONS

Coagulation pathway sensors (F3/TF, F2R/PAR-1) are expressed in MB in a subtype-specific manner, and may be functionally linked to SHH and MET circuitry. Thus coagulation system perturbations may elicit subtype/context-specific changes in vascular and cellular responses in MB.

Nitric oxide-matrix metaloproteinase-9 interactions: biological and pharmacological significance--NO and MMP-9 interactions

Nitric oxide (NO) and matrix metalloproteinase 9 (MMP-9) levels are found to increase in inflammation states and in cancer, and their levels may be reciprocally modulated. Understanding interactions between NO and MMP-9 is of biological and pharmacological relevance and may prove crucial in designing new therapeutics. The reciprocal interaction between NO and MMP-9 have been studied for nearly twenty years but to our knowledge, are yet to be the subject of a review. This review provides a summary of published data regarding the complex and sometimes contradictory effects of NO on MMP-9. We also analyse molecular mechanisms modulating and mediating NO-MMP-9 interactions. Finally, a potential therapeutic relevance of these interactions is presented.

Osteopontin is a promoter for hepatocellular carcinoma metastasis: a summary of 10 years of studies

In this review, we summarize the novel findings from our series of studies on the leading metastasis-related gene, osteopontin (OPN). In our previous gene expression profiling study, OPN was identified as one of the leading genes associated with the metastasis of hepatocellular carcinoma (HCC). We focused on OPN to evaluate its prognostic values and important roles in HCC metastasis. A retrospective study of large cohorts of HCC patients demonstrated that plasma OPN level was one of the leading independent prognostic factors for HCC patients, even in the early stage of HCC, and could serve as a surrogate serologic biomarker for monitoring the treatment response and tumor recurrence after HCC resection. Using both in vitro and in vivo investigations, we found that OPN has an important role in metastasis and tumor growth of HCC and is an attractive potential therapeutic target for combating HCC metastasis. We also found that OPN⁺ HCC cells have much more amplifications at chromosomal regions, and promoter polymorphisms are important in the regulation of OPN expression and tumor growth and lung metastasis of HCC.

[Advances on mechanisms of coagulation with non-small cell lung cancer]

Recently, researchers have been increasingly finding coagulation disorders are commonly the first sign of malignancy. It has now been established that cancer development leads to an increased risk of thrombosis, and conversely, excessive activation of blood coagulation profoundly influences cancer progression. In patients with lung cancer, a sustained stimulation of blood coagulation takes place. Cancer cells trigger coagulation through expression of tissue factor, and affect coagulation through expression of thrombin, release of microparticles that augment coagulation and so on. Coagulation also facilitates tumour progression through release of platelet granule contents, inhibition of natural killer cells and recruitment of macrophages. Non-small cell lung cancer (NSCLC) accounts for about 80%-85% of all lung malignancies. In the present review, we summarized the newly updated data about the physiopathological mechanisms of various components of the clotting system in different stages of carcinogenesis in NSCLC.

Pathologies at the nexus of blood coagulation and inflammation: thrombin in hemostasis, cancer, and beyond

Thrombin is the protease involved in blood coagulation. Its deregulation can lead to hemostatic abnormalities, which range from subtle subclinical to serious life-threatening coagulopathies, i.e., during septicemia. Additionally, thrombin plays important roles in many (patho)physiological conditions that reach far beyond its well-established role in stemming blood loss and thrombosis, including embryonic development and angiogenesis but also extending to inflammatory processes, complement activation, and even tumor biology. In this review, we will address thrombin's broad roles in diverse (patho)physiological processes in an integrative way. We will also discuss thrombin as an emerging major target for novel therapies.

Peptide-based selective inhibitors of matrix metalloproteinase-mediated activities

The matrix metalloproteinases (MMPs) exhibit a broad array of activities, some catalytic and some non-catalytic in nature. An overall lack of selectivity has rendered small molecule, active site targeted MMP inhibitors problematic in execution. Inhibitors that favor few or individual members of the MMP family often take advantage of interactions outside the enzyme active site. We presently focus on peptide-based MMP inhibitors and probes that do not incorporate conventional Zn²⁺ binding groups. In some cases, these inhibitors and probes function by binding only secondary binding sites (exosites), while others bind both exosites and the active site. A myriad of MMP mediated-activities beyond selective catalysis can be inhibited by peptides, particularly cell adhesion, proliferation, motility, and invasion. Selective MMP binding peptides comprise highly customizable, unique imaging agents. Areas of needed improvement for MMP targeting peptides include binding affinity and stability.

Matrix metalloproteinase-2 cleavage of the β1 integrin ectodomain facilitates colon cancer cell motility

Cancer cell invasion is a key element in metastasis that requires integrins for adhesion/de-adhesion, as well as matrix metalloproteinases (MMPs) for focalized proteolysis. Herein we show that MMP-2 is up-regulated in resected colorectal tumors and degrades β1 integrins with the release of fragments containing the β1 I-domain. The β1 cleavage pattern is similar to that produced by digestion of α5β1 and α2β1 with MMP-2. Two such fragments, at 25 and 75 kDa, were identified after immunoprecipitation, with monoclonal antibody BD610468 reacting with the NH(2)-terminal I-like ectodomain followed by SDS-PAGE and microsequencing using electrospray (ISI-Q-TOF-Micromass) spectrometry. Cleavage of the β1 integrin can be abolished by inhibition of MMP-2 activity; it can be induced by up-regulation of MMP-2 expression, as exemplified by HT29 colon cancer cells transfected with pCMV6-XL5-MMP-2. Co-immunoprecipitation studies of colon cancer cells showed that the β1 integrin subunit is associated with MMP-2. The MMP-2-mediated shedding of the I-like domain from β1 integrins resulted in decreased adhesion of colon cancer cells to collagen and fibronectin, thus abolishing their receptivity. Furthermore, such cells showed enhanced motility as evaluated by a "wound healing-like" assay and time-lapse microscopy, indicating their increased invasiveness. Altogether, our data demonstrate that MMP-2 amplifies the motility of colon cancer cells, not only by digesting the extracellular matrix components in the vicinity of cancer cells but also by inactivating their major β1 integrin receptors.

Cooperation of protease-activated receptor 1 and integrin ανβ5 in thrombin-mediated lung cancer cell invasion

Protease-activated receptor 1 (PAR1) and integrins play an important role in thrombin-mediated tumor cell invasion. However, the role of PAR1 and integrin ανβ5 and the relationship between the two receptors in thrombin-induced lung cancer invasion remains unknown. Moreover, the mechanisms through which immobilized thrombin facilitates tumor invasion are poorly understood. In this study, both native and immobilized thrombin promoted lung cancer cell adhesion, migration and extracellular signal-regulated kinase phosphorylation. Integrin ανβ5 is involved in both native and immobilized thrombin-mediated tumor cell invasion; PAR1 had no effect on immobilized thrombin-mediated cell invasion. PAR1 and integrin ανβ5 colocalized on the surface of native thrombin-treated cells. This study suggests that targeting of integrin ανβ5 or the PAR1-integrin ανβ5 complex may present an important therapeutic opportunity to prevent lung cancer invasion.

Functional regulation of HIF-1α under normoxia--is there more than post-translational regulation?

The hypoxia-inducible factor-1 (HIF-1) is an oxygen-regulated transcriptional activator playing a pivotal role in mammalian physiology and disease pathogenesis, e.g., HIF-1 is indispensable in a broad range of developmental stages in different tumors. Its post-translational regulation via PHDs under the influence of hypoxia is widely investigated and accepted. Different non-hypoxic stimuli such as lipopolysaccharides (LPS), thrombin, and angiotensin II (Ang II), have been proven to enhance HIF-1 levels through activation of regulative mechanisms distinct from protein stabilization. Some of these stimuli specifically regulate HIF-1α at the transcriptional, post-transcriptional, or translational level, whereas others additionally influence post-translational modifications. Thus, it is difficult for the investigators to discern the impact of the different mechanisms leading to functional HIF-1 protein. Nevertheless, profound knowledge of additional regulatory networks appears to depict new therapeutic opportunities and thus is an interesting and important field for further investigations.

ETS-1 protein regulates vascular endothelial growth factor-induced matrix metalloproteinase-9 and matrix metalloproteinase-13 expression in human ovarian carcinoma cell line SKOV-3

Matrix metalloproteinase-mediated degradation of extracellular matrix is a crucial event for invasion and metastasis of malignant cells. The expressions of matrix metalloproteinases (MMPs) are regulated by different cytokines and growth factors. VEGF, a potent angiogenic cytokine, induces invasion of ovarian cancer cells through activation of MMPs. Here, we demonstrate that invasion and scattering in SKOV-3 cells were induced by VEGF through the activation of p38 MAPK and PI3K/AKT pathways. VEGF induced the expression of MMP-2, MMP-9, and MMP-13 and hence regulated the metastasis of SKOV-3 ovarian cancer cells, and the activities of these MMPs were reduced after inhibition of PI3K/AKT and p38 MAPK pathways. Interestingly, VEGF induced expression of ETS-1 factor, an important trans-regulator of different MMP genes. ETS-1 bound to both MMP-9 and MMP-13 promoters. Furthermore, VEGF acted through its receptor to perform the said functions. In addition, VEGF-induced MMP-9 and MMP-13 expression and in vitro cell invasion were significantly reduced after knockdown of ETS-1 gene. Again, VEGF-induced MMP-9 and MMP-13 promoter activities were down-regulated in ETS-1 siRNA-transfected cells. VEGF enriched ETS-1 in the nuclear fraction in a dose-dependent manner. VEGF-induced expression of ETS-1 and its nuclear localization were blocked by specific inhibitors of the PI3K and p38 MAPK pathways. Therefore, based on these observations, it is hypothesized that the activation of PI3K/AKT and p38 MAPK by VEGF results in ETS-1 gene expression, which activates MMP-9 and MMP-13, leading to the invasion and scattering of SKOV-3 cells. The study provides a mechanistic insight into the prometastatic functions of VEGF-induced expression of relevant MMPs.

Human matrix metalloproteinases: an ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes.

Matrix metalloproteinase-9 inhibition reduces inflammation and improves motility in murine models of postoperative ileus

BACKGROUND & AIMS

Matrix metalloproteinase (MMP)-9, a member of the gelatinase family of MMPs, mediates leukocyte migration during inflammation. Inflammation contributes to development of postoperative ileus (POI), which is caused by physical disturbances to the bowel during abdominal surgery. We evaluated the role of MMP-9 in POI and investigated whether disruption of MMP-9 or administration of an inhibitor of MMP-9 activity reduced cellular inflammation and bowel dysmotility in rat and mouse models of POI.

METHODS

Mice and rats underwent laparotomy and bowel manipulation; bowel tissues were collected 3 to 24 hours later and analyzed by real-time reverse-transcriptase polymerase chain reaction, immunoblot, in situ zymography, and functional analyses.

RESULTS

Bowel manipulation resulted in a time-dependent increase in MMP-9 expression within the intestinal muscularis; increases in MMP-9 messenger RNA were inducible nitric oxide synthase dependent. Immunoblot analyses confirmed the presence of the proenzyme and the catalytically active form of MMP-9. Administration of MMP-2/MMP-9 II, a dual active-site inhibitor, reduced the number of myeloperoxidase-positive immune cells that infiltrated the muscularis and prevented the surgically induced reduction in bowel smooth muscle contractility. Zymography analysis, performed in muscularis whole mounts in situ, indicated that MMP-9 and not MMP-2 mediated the gelatinase activity observed in infiltrating cells. MMP-9 knockout mice were protected from the inflammation and dysmotility associated with POI.

CONCLUSIONS

MMP-9 mediates cellular inflammatory responses within the intestinal muscularis in mouse and rat models of POI. Inhibition of MMP-9 activity reduced recruitment of immune cells to the intestinal muscularis, preventing loss of smooth muscle contractility. Induction of MMP-9 expression requires inducible nitric oxide synthase.

Microarray and proteomic analysis of breast cancer cell and osteoblast co-cultures: role of osteoblast matrix metalloproteinase (MMP)-13 in bone metastasis

Dynamic reciprocal interactions between a tumor and its microenvironment impact both the establishment and progression of metastases. These interactions are mediated, in part, through proteolytic sculpting of the microenvironment, particularly by the matrix metalloproteinases, with both tumors and stroma contributing to the proteolytic milieu. Because bone is one of the predominant sites of breast cancer metastases, we used a co-culture system in which a subpopulation of the highly invasive human breast cancer cell line MDA-MB-231, with increased propensity to metastasize to bone, was overlaid onto a monolayer of differentiated osteoblast MC3T3-E1 cells in a mineralized osteoid matrix. CLIP-CHIP® microarrays identified changes in the complete protease and inhibitor expression profile of the breast cancer and osteoblast cells that were induced upon co-culture. A large increase in osteoblast-derived MMP-13 mRNA and protein was observed. Affymetrix analysis and validation showed induction of MMP-13 was initiated by soluble factors produced by the breast tumor cells, including oncostatin M and the acute response apolipoprotein SAA3. Significant changes in the osteoblast secretomes upon addition of MMP-13 were identified by degradomics from which six novel MMP-13 substrates with the potential to functionally impact breast cancer metastasis to bone were identified and validated. These included inactivation of the chemokines CCL2 and CCL7, activation of platelet-derived growth factor-C, and cleavage of SAA3, osteoprotegerin, CutA, and antithrombin III. Hence, the influence of breast cancer metastases on the bone microenvironment that is executed via the induction of osteoblast MMP-13 with the potential to enhance metastases growth by generating a microenvironmental amplifying feedback loop is revealed.

Tissue factor, blood coagulation, and beyond: an overview

Emerging evidence shows a broad spectrum of biological functions of tissue factor (TF). TF classical role in initiating the extrinsic blood coagulation and its direct thrombotic action in close relation to cardiovascular risks have long been established. TF overexpression/hypercoagulability often observed in many clinical conditions certainly expands its role in proinflammation, diabetes, obesity, cardiovascular diseases, angiogenesis, tumor metastasis, wound repairs, embryonic development, cell adhesion/migration, innate immunity, infection, pregnancy loss, and many others. This paper broadly covers seminal observations to discuss TF pathogenic roles in relation to diverse disease development or manifestation. Biochemically, extracellular TF signaling interfaced through protease-activated receptors (PARs) elicits cellular activation and inflammatory responses. TF diverse biological roles are associated with either coagulation-dependent or noncoagulation-mediated actions. Apparently, TF hypercoagulability refuels a coagulation-inflammation-thrombosis circuit in “autocrine” or “paracrine” fashions, which triggers a wide spectrum of pathophysiology. Accordingly, TF suppression, anticoagulation, PAR blockade, or general anti-inflammation offers an array of therapeutical benefits for easing diverse pathological conditions.

Thrombin-induced Migration and Matrix Metalloproteinase-9 Expression Are Regulated by MAPK and PI3K Pathways in C6 Glioma Cells

Glioblastoma multiforme is one of the most common and aggressive tumors in central nervous system. It often possesses characteristic necrotic lesions with hemorrhages, which increase the chances of exposure to thrombin. Thrombin has been known as a regulator of MMP-9 expression and cancer cell migration. However, the effects of thrombin on glioma cells have not been clearly understood. In the present study, influences of thrombin on glioma cell migration were examined using Boyden chamber migration assay and thrombin-induced changes in MMP-9 expression were measured using zymography, semi-quantitative RT-PCR, and Western blotting. Furthermore, underlying signaling pathways by which thrombin induces MMP-9 expression were examined. Thrombin-induced migration and MMP-9 expression were significantly potentiated in the presence of wortmannin, a PI3K inhibitor, whereas MAPK inhibitors suppressed thrombin-induced migration and MMP-9 expression in C6 glioma cells. The present data strongly demonstrate that MAPK and PI3K pathways evidently regulate thrombin-induced migration and MMP-9 expression of C6 glioma cells. Therefore, the control of these pathways might be a beneficial therapeutic strategy for treatment of invasive glioblastoma multiforme.

Brain pericytes among cells constituting the blood-brain barrier are highly sensitive to tumor necrosis factor-α, releasing matrix metalloproteinase-9 and migrating in vitro

Background

Increased matrix metalloproteinase (MMP)-9 in the plasma and brain is associated with blood-brain barrier (BBB) disruption through proteolytic activity in neuroinflammatory diseases. MMP-9 is present in the brain microvasculature and its vicinity, where brain microvascular endothelial cells (BMECs), pericytes and astrocytes constitute the BBB. Little is known about the cellular source and role of MMP-9 at the BBB. Here, we examined the ability of pericytes to release MMP-9 and migrate in response to inflammatory mediators in comparison with BMECs and astrocytes, using primary cultures isolated from rat brains.

Methods

The culture supernatants were collected from primary cultures of rat brain endothelial cells, pericytes, or astrocytes. MMP-9 activities and levels in the supernatants were measured by gelatin zymography and western blot, respectively. The involvement of signaling molecules including mitogen-activated protein kinases (MAPKs) and phosphoinositide-3-kinase (PI3K)/Akt in the mediation of tumor necrosis factor (TNF)-α-induced MMP-9 release was examined using specific inhibitors. The functional activity of MMP-9 was evaluated by a cell migration assay.

Results

Zymographic and western blot analyses demonstrated that TNF-α stimulated pericytes to release MMP-9, and this release was much higher than from BMECs or astrocytes. Other inflammatory mediators [interleukin (IL)-1β, interferon-γ, IL-6 and lipopolysaccharide] failed to induce MMP-9 release from pericytes. TNF-α-induced MMP-9 release from pericytes was found to be mediated by MAPKs and PI3K. Scratch wound healing assay showed that in contrast to BMECs and astrocytes the extent of pericyte migration was significantly increased by TNF-α. This pericyte migration was inhibited by anti-MMP-9 antibody.

Conclusion

These findings suggest that pericytes are most sensitive to TNF-α in terms of MMP-9 release, and are the major source of MMP-9 at the BBB. This pericyte-derived MMP-9 initiated cellular migration of pericytes, which might be involved in pericyte loss in the damaged BBB.

MMP9 cleavage of the β4 integrin ectodomain leads to recurrent epithelial erosions in mice

Integrin α6β4 is an integral membrane protein within hemidesmosomes and it mediates adhesion of epithelial cells to their underlying basement membrane. During wound healing, disassembly of hemidesmosomes must occur for sheet movement-mediated cell migration. The mechanisms of disassembly and reassembly of hemidesmosomes are not fully understood. The current study was initiated to understand the underlying cause of recurrent corneal erosions in the mouse. Here, we show that in vivo: (1) MMP9 levels are elevated and β4 integrin is partially cleaved in epithelial cell extracts derived from debridement wounded corneas; (2) the β4 ectodomain is missing from sites where erosions develop; and (3) β4 cleavage can be reduced by inhibiting MMP activity. Although β4, α3 and β1 integrins were all cleaved by several MMPs, only MMP9 was elevated in cell extracts derived from corneas with erosions. Coimmunoprecipitation studies showed that β4 integrin associates with MMP9, and protein clustering during immunoprecipitation induced proteolytic cleavage of the β4 integrin extracellular domain, generating a 100 kDa β4 integrin cytoplasmic domain fragment. Confocal imaging with three-dimensional reconstruction showed that MMP9 localizes at erosion sites in vivo where the ectodomain of β4 integrin is reduced or absent. MMP activation experiments using cultured corneal and epidermal keratinocytes showed reduced levels of α6β4 and β1 integrins within 20 minutes of phorbol ester treatment. This report is the first to show that β4 integrin associates with MMP9 and that its ectodomain is a target for cleavage by MMP9 in vivo under pathological conditions.