Pervanadate-induced shedding of the intercellular adhesion molecule (ICAM)-1 ectodomain is mediated by membrane type-1 matrix metalloproteinase (MT1-MMP)

Proteolytic modulation of tumor microenvironment signals during cancer progression

Under normal conditions, the cellular microenvironment is optimized for the proper functioning of the tissues and organs. Cells recognize and communicate with the surrounding cells and extracellular matrix to maintain homeostasis. When cancer arises, the cellular microenvironment is modified to optimize its malignant growth, evading the host immune system and finding ways to invade and metastasize to other organs. One means is a proteolytic modification of the microenvironment and the signaling molecules. It is now well accepted that cancer progression relies on not only the performance of cancer cells but also the surrounding microenvironment. This mini-review discusses the current understanding of the proteolytic modification of the microenvironment signals during cancer progression.

Emerging roles of MT-MMPs in embryonic development

Membrane-type matrix metalloproteinases (MT-MMPs) are cell membrane-tethered proteinases that belong to the family of the MMPs. Apart from their roles in degradation of the extracellular milieu, MT-MMPs are able to activate through proteolytic processing at the cell surface distinct molecules such as receptors, growth factors, cytokines, adhesion molecules, and other pericellular proteins. Although most of the information regarding these enzymes comes from cancer studies, our current knowledge about their contribution in distinct developmental processes occurring in the embryo is limited. In this review, we want to summarize the involvement of MT-MMPs in distinct processes during embryonic morphogenesis, including cell migration and proliferation, epithelial-mesenchymal transition, cell polarity and branching, axon growth and navigation, synapse formation, and angiogenesis. We also considered information about MT-MMP functions from studies assessed in pathological conditions and compared these data with those relevant for embryonic development.

ADAM10 and ADAM17 proteases mediate proinflammatory cytokine-induced and constitutive cleavage of endomucin from the endothelial surface

Contact between inflammatory cells and endothelial cells (ECs) is a crucial step in vascular inflammation. Recently, we demonstrated that the cell-surface level of endomucin (EMCN), a heavily O-glycosylated single-transmembrane sialomucin, interferes with the interactions between inflammatory cells and ECs. We have also shown that, in response to an inflammatory stimulus, EMCN is cleared from the cell surface by an unknown mechanism. In this study, using adenovirus-mediated overexpression of a tagged EMCN in human umbilical vein ECs, we found that treatment with tumor necrosis factor α (TNF-α) or the strong oxidant pervanadate leads to loss of cell-surface EMCN and increases the levels of the C-terminal fragment of EMCN 3- to 4-fold. Furthermore, treatment with the broad-spectrum matrix metalloproteinase inhibitor batimastat (BB94) or inhibition of ADAM metallopeptidase domain 10 (ADAM10) and ADAM17 with two small-molecule inhibitors, GW280264X and GI254023X, or with siRNA significantly reduced basal and TNFα-induced cell-surface EMCN cleavage. Release of the C-terminal fragment of EMCN by TNF-α treatment was blocked by chemical inhibition of ADAM10 alone or in combination with ADAM17. These results indicate that cell-surface EMCN undergoes constitutive cleavage and that TNF-α treatment dramatically increases this cleavage, which is mediated predominantly by ADAM10 and ADAM17. As endothelial cell-surface EMCN attenuates leukocyte-EC interactions during inflammation, we propose that EMCN is a potential therapeutic target to manage vascular inflammation.

The Association of Matrix Metalloproteinases with Chronic Kidney Disease and Peripheral Vascular Disease: A Light at the End of the Tunnel?

: Chronic Kidney Disease (CKD) represents a risk factor for fatal and nonfatal cardiovascular (CV) events, including peripheral vascular disease (PVD). This occurs because CKD encompasses several factors that lead to poor prognoses, mainly due to a reduction of the estimated glomerular filtration rate (eGFR), the presence of proteinuria, and the uremic inflammatory milieu. The matrix metalloproteinases (MMPs) are a group of zinc-containing endopeptidases implicated in extracellular matrix (ECM) remodeling, a systemic process in tissue homeostasis. MMPs play an important role in cell differentiation, angiogenesis, inflammation, and vascular damage. Our aim was to review the published evidence regarding the association between MMPs, PVD, and CKD to find possible common pathophysiological mechanisms. MMPs favor ECM deposition through the glomeruli, and start the shedding of cellular junctions and epithelial-mesenchymal transition in the renal tubules. MMP-2 and -9 have also been associated with the presence of systemic vascular damage, since they exert a pro-inflammatory and proatherosclerotic actions. An imbalance of MMPs was found in the context of PVD, where MMPs are predictors of poor prognoses in patients who underwent lower extremity revascularization. MMP circulating levels are increased in both conditions, i.e., that of CKD and PVD. A possible pathogenic link between these conditions is represented by the enhanced production of transforming growth factor-β that worsens vascular calcifications and atherosclerosis and the development of proteinuria in patients with increased levels of MMPs. Proteinuria has been recognized as a marker of systemic vascular damage, and this may explain in part the increase in CV risk that is manifest in patients with CKD and PVD. In conclusion, MMPs can be considered a useful tool by which to stratify CV risk in patients with CKD and PVD. Further studies are needed to investigate the causal-relationships between MMPs, CKD, and PVD, and to optimize their prognostic and predictive (in response to treatments) roles.

Matrix Metalloproteases as Influencers of the Cells' Social Media

Matrix metalloproteinases (MMPs) have been studied in the context of cancer due to their ability to increase cell invasion, and were initially thought to facilitate metastasis solely through the degradation of the extracellular matrix (ECM). MMPs have also been investigated in the context of their ECM remodeling activity in several acute and chronic inflammatory diseases. However, after several MMP inhibitors failed in phase III clinical trials, a global reassessment of their biological functions was undertaken, which has revealed multiple unanticipated functions including the processing of chemokines, cytokines, and cell surface receptors. Despite what their name suggests, the matrix aspect of MMPs could contribute to a lesser part of their physiological functions in inflammatory diseases, as originally anticipated. Here, we present examples of MMP substrates implicated in cell signaling, independent of their ECM functions, and discuss the impact for the use of MMP inhibitors.

Matrix Metalloproteinases in Bone Resorption, Remodeling, and Repair

Matrix metalloproteinases (MMPs) are the major protease family responsible for the cleavage of the matrisome (global composition of the extracellular matrix (ECM) proteome) and proteins unrelated to the ECM, generating bioactive molecules. These proteins drive ECM remodeling, in association with tissue-specific and cell-anchored inhibitors (TIMPs and RECK, respectively). In the bone, the ECM mediates cell adhesion, mechanotransduction, nucleation of mineralization, and the immobilization of growth factors to protect them from damage or degradation. Since the first description of an MMP in bone tissue, many other MMPs have been identified, as well as their inhibitors. Numerous functions have been assigned to these proteins, including osteoblast/osteocyte differentiation, bone formation, solubilization of the osteoid during bone resorption, osteoclast recruitment and migration, and as a coupling factor in bone remodeling under physiological conditions. In turn, a number of pathologies, associated with imbalanced bone remodeling, arise mainly from MMP overexpression and abnormalities of the ECM, leading to bone osteolysis or bone formation. In this review, we will discuss the functions of MMPs and their inhibitors in bone cells, during bone remodeling, pathological bone resorption (osteoporosis and bone metastasis), bone repair/regeneration, and emergent roles in bone bioengineering.

Antibodies to paraoxonase 1 are associated with oxidant status and endothelial activation in rheumatoid arthritis

Anti-paraoxonase 1 (PON1) antibodies could be a potential missing link between oxidative status, inflammation and cardiovascular disease (CVD) in rheumatoid arthritis (RA) patients. Therefore, they could represent an emerging clinical biomarker of CV risk in this condition.

Systematic phenotyping and correlation of biomarkers with lung function and histology in lung fibrosis

To date, phenotyping and disease course prediction in idiopathic pulmonary fibrosis (IPF) primarily relies on lung function measures. Blood biomarkers were recently proposed for diagnostic and outcome prediction in IPF, yet their correlation with lung function and histology remains unclear. Here, we comprehensively assessed biomarkers in liquid biopsies and correlated their abundance with lung function and histology during the onset, progression, and resolution of lung fibrosis, with the aim to more precisely evaluate disease progression in the preclinical model of bleomycin-induced pulmonary fibrosis in vivo. Importantly, the strongest correlation of lung function with histological extent of fibrosis was observed at day 14, whereas lung function was unchanged at days 28 and 56, even when histological assessment showed marked fibrotic lesions. Although matrix metalloproteinase-7 (MMP-7), MMP-9, and PAI-1 were significantly elevated in broncheoalveolar lavage of fibrotic mice, only soluble ICAM-1 (sICAM-1) was elevated in the peripheral blood of fibrotic mice and was strongly correlated with the extent of fibrosis. Importantly, tissue-bound ICAM-1 was also elevated in lung homogenates, with prominent staining in hyperplastic type II alveolar epithelial and endothelial cells. In summary, we show that lung function decline is not a prerequisite for histologically evident fibrosis, particularly during the onset or resolution thereof. Plasma levels of sICAM-1 strongly correlate with the extent of lung fibrosis, and may thus be considered for the assessment of intraindividual therapeutic studies in preclinical studies of pulmonary fibrosis.

Downregulation of human intercellular adhesion molecule-1 attenuates the metastatic ability in human breast cancer cell lines

Intercellular adhesion molecule-1 (ICAM-1) is a cell surface glycoprotein that belongs to immunoglobulin superfamily and plays an important role in tumor cell expansion or metastasis. However, the detailed mechanisms of ICAM-1 in breast cancer remain unclear. In this study, we evaluated the expression level of ICAM-1 in breast cancer using tissue microarray and clinical tissue specimens by immunohistochemical method, and the results revealed that ICAM-1 is highly expressed in the breast cancer tissues. To investigate whether ICAM-1 can affect the metastasis ability in breast cancer, we knocked down ICAM-1 expression in breast cancer cell line MCF-7 by using lentivirus-mediated RNA interference (RNAi). As a result, we stably silenced ICAM-1 expression in MCF-7 cells by infection with lentivirus expressing green fluorescent protein (GFP), the change of metastatic ability of MCF-7 cells was assessed by wound-healing assay, Transwell assay or clone formation assay. Our results showed that silencing of ICAM-1 can inhibit the metastatic ability of MCF-7 cell lines in vitro significantly, and the decreased migration and invasion was accompanied by a reduction of MMP-14. These results implying that ICAM-1 might be involved in the progression of breast cancer metastasis and lentivirus-mediated silencing of ICAM-1 might be a potential therapeutic approach for the treatment of breast cancer.

Leptin-mediated regulation of ICAM-1 is Rho/ROCK dependent and enhances gastric cancer cell migration

Background:

Our previous study indicates that leptin enhances gastric cancer (GC) invasion. However, the exact effect of leptin on GC metastasis and its underlying mechanism remain unclear. Intercellular adhesion molecule-1 (ICAM-1), a major molecule in stabilising cell–cell and cell–extracellular matrix interactions, is overexpressed and has crucial roles in tumour metastasis.

Methods:

Here, we investigated leptin and ICAM-1 expression in GC tissues. Furthermore, we characterised the influence of leptin on ICAM-1 expression in GC cells and elucidated the underlying mechanism.

Results:

Leptin and ICAM-1 were overexpressed in GC tissues, and a strong positive correlation was observed. They were also related with clinical stage or lymph node metastasis. Furthermore, leptin induced GC cell (AGS and MKN-45) migration by upregulating ICAM-1, and knockdown of ICAM-1 by small interference RNA (siRNA) blocked this process. Cell surface ICAM-1, as well as soluble ICAM-1 (sICAM-1), was also enhanced by leptin. Moreover, leptin increased ICAM-1 expression through Rho/ROCK pathway, which was attenuated by pharmacological inhibition of Rho (C3 transferase) or its downstream effector kinase Rho-associated protein kinase (ROCK) (Y-27632).

Conclusions:

Our findings indicate that leptin enhances GC cell migration by increasing ICAM-1 through Rho/ROCK pathway, which might provide new insight into the significance of leptin in GC.

Intercellular adhesion molecule 1: recent findings and new concepts involved in mammalian spermatogenesis

Spermatogenesis, the process of spermatozoa production, is regulated by several endocrine factors, including testosterone, follicle stimulating hormone, luteinizing hormone and estradiol 17β. For spermatogenesis to reach completion, developing germ cells must traverse the seminiferous epithelium while remaining transiently attached to Sertoli cells. If germ cell adhesion were to be compromised for a period of time longer than usual, germ cells would slough from the seminiferous epithelium and infertility would result. Presently, Sertoli-germ cell adhesion is known to be mediated largely by classical and desmosomal cadherins. More recent studies, however, have begun to expand long-standing concepts and to examine the roles of other proteins such as intercellular adhesion molecules. In this review, we focus on the biology of intercellular adhesion molecules in the mammalian testis, hoping that this information is useful in the design of future studies.

Who decides when to cleave an ectodomain?

Many life-essential molecules such as growth factors, cytokines, ectoenzymes, and decoy receptors are produced by ectodomain cleavage of transmembrane precursor molecules. Not surprisingly, misregulation of such essential functions is linked to numerous diseases. Ectodomain cleavage is the function of transmembrane ADAMs (a disintegrin and metalloprotease) and other membrane-bound metalloproteases, which have an extracellular catalytic domain. Almost all work on ectodomain cleavage regulation has focused on the control of enzyme activity determined by substrate cleavage as surrogate. However, the number of substrates far exceeds the number of enzymes. Specificity can therefore not be achieved by solely modulating enzyme activity. Here, we argue that specific regulatory pathways must exist to control the availability and susceptibility of substrates.

Matrix metalloproteinases in kidney homeostasis and diseases

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that have been increasingly linked to both normal physiology and abnormal pathology in the kidney. Collectively able to degrade all components of the extracellular matrix, MMPs were originally thought to antagonize the development of fibrotic diseases solely through digestion of excessive matrix. However, increasing evidence has shown that MMPs play a wide variety of roles in regulating inflammation, epithelial-mesenchymal transition, cell proliferation, angiogenesis, and apoptosis. We now have robust evidence for MMP dysregulation in a multitude of renal diseases including acute kidney injury, diabetic nephropathy, glomerulonephritis, inherited kidney disease, and chronic allograft nephropathy. The goal of this review is to summarize current findings regarding the role of MMPs in kidney diseases as well as the mechanisms of action of this family of proteases.

Plasma from preeclamptic women activates endothelial cells via monocyte activation in vitro

In this study we tested whether plasma from preeclamptic women contains factors that can activate endothelial cells in the presence of monocytes in vitro. Plasma from preeclamptic women (n=6), healthy pregnant women (n=6) and nonpregnant women (n=6) was incubated with mono-cultures and co-cultures of human umbilical vein endothelial cells (HUVEC) and monomac-6 monocytes. Reactive oxygen species (ROS) production and ICAM-1 expression were measured using flow cytometry. Whether scavenging of ROS by superoxide dismutase and catalase inhibited HUVEC ICAM-1 expression was also investigated. We found that in HUVEC co-cultured with monomac-6 cells but not in HUVEC cultured alone, ICAM-1 was upregulated after incubation with plasma from preeclamptic women but not plasma from non-pregnant women. Also in co-cultures, monomac-6 ICAM-1 was upregulated by plasma from preeclamptic women, while in both mono- and co-cultures monomac-6 ROS production was upregulated by plasma from pregnant and preeclamptic women, compared with plasma from non-pregnant women. Scavenging of ROS by superoxide dismutase and catalase resulted in a further upregulation of HUVEC ICAM-1 after incubation with plasma from preeclamptic women, compared with incubation without superoxide dismutase and catalase. These results show that endothelial cells in vitro are activated by plasma of preeclamptic women only if they are co-cultured with monocytes. This upregulation appeared not to be due to extracellular ROS production by monocytes or HUVEC, pointing to involvement of other mechanisms. Our data suggest that plasma of preeclamptic women activates monocytes, and that these monocytes subsequently activate endothelial cells.

The membrane type matrix metalloproteinase MMP14 mediates constitutive shedding of MHC class I chain-related molecule A independent of A disintegrin and metalloproteinases

Engagement of tumor cell surface MHC class I chain-related molecule A (MICA) to NKG2D stimulates NK and T cell antitumor immunity. Shedding of MICA by tumor cells facilitates tumor immune evasion, which may in part contribute to tumor progression. Thus, elucidating the mechanisms by which tumors shed MIC is of great importance for therapy to reinforce NK and T cell antitumor immunity. In this study, we report that the membrane type matrix metalloproteinase (MMP)14 mediates MICA shedding. Suppression of MMP14 expression blocks MICA shedding. Concomitantly, overexpression of MMP14 enhances MICA shedding. The regulation of MICA shedding by MMP14 is independent of the activity of a disintegrin and metalloproteinases, which have been reported to mediate MICA shedding. Finally, MMP14 expression in MICA-positive tumor cells regulates the sensitivity of tumor cells to NK cell killing. These findings suggest that MMP14 may be a new target for tumor immune therapy.

Altered expression of glycoproteins on the cell surface of Jurkat cells during etoposide-induced apoptosis: shedding and intracellular translocation of glycoproteins

BACKGROUND

The glycoproteins on the cell surface are altered during apoptosis and play an important role in phagocytic clearance of apoptotic cells.

METHODS

We classified Jurkat cells treated with etoposide as viable and early apoptotic cells, late apoptotic cells or secondary necrotic cells based on propidium iodide staining and scattered grams and estimated the expression levels of glycoproteins on the cell surface.

RESULTS

The cell surface expression levels of intercellular adhesion molecules (ICAM)-2 and -3 on the apoptotic cells were markedly lower, while those of calnexin, calreticulin, and lysosome-associated membrane proteins (LAMP)-1 and -2 were significantly higher compared to non-apoptotic cells. These decreases in ICAM-2 and -3 on the apoptotic cell surface were reduced in the presence of metalloproteinase inhibitors and caspase inhibitors, respectively. Confocal microscopic analysis revealed that calnexin and calreticulin were assembled around fragmented nuclei of blebbed apoptotic cells.

CONCLUSIONS

These results suggest that alteration of glycoproteins on the cell surface during apoptosis is associated with shedding and intracellular translocation of glycoproteins.

Regulation of angiogenesis: apoptotic cues from the ECM

The extracellular matrix (ECM) acts both as a physical scaffold for cells and as a repository for growth factors. Moreover, ECM structure and physical-chemical properties convey precise information to cells that profoundly influences their biology by interactions with cell surface receptors termed integrins. During angiogenesis, the perivascular ECM plays a critical role in determining the proliferative, invasive and survival responses of the local vascular cells to the angiogenic growth factors. Dynamic changes in both the ECM and the local vascular cells act in concert to regulate new blood vessel growth. The digestion of ECM components by proteolysis is critical for the invasive capacity of endothelial cells, but also creates ECM fragments, which antagonize the mechanosensory function of integrins, and can be apoptogenic. Here, we discuss the roles of integrins in modulating cellular responses to a changing ECM, in particular the regulation of survival and invasion among invasive endothelial cells.