基质金属蛋白酶的结构、功能和调节

基质金属蛋白酶（MMPs)是一个蛋白水解酶大家族，可降解细胞外很多种基质成分。根据体外底物专一性，MMPs可分为胶原酶，明胶酶，基质降解素以及膜型MMPs等，越来越多的研究表明，MMPs在肿瘤侵袭转移中起着重要的作用，而且此作用不仅仅限于它有利于细胞外基质的降解，还对肿瘤微环境的维持和促进肿瘤生长起着重要作用，本文对MMPs的结构，功能及其调节进行综述。     

Matrix metalloproteinases in tumour invasion and metastasis.

The matrix metalloproteinases (MMPs) are a large family of proteolytic enzymes, which are involved in the degradation of many different components of the extracellular matrix. The MMPs have been classified into different groups including collagenases, gelatinases, stromelysins, and others, particularly membrane-type MMPs, based mainly on the in vitro substrate specificity of individual MMPs. There is increasing evidence to indicate that individual MMPs have important roles in tumour invasion and metastasis. However, the current concept of the role of MMPs in tumour invasion is that they not only have a direct role in tumour invasion by facilitating extracellular matrix degradation, but as a consequence they also have an important role in maintaining the tumour micro-environment and thus promoting tumour growth. Inhibiting the action of MMPs represents a new therapeutic approach for the treatment of individual types of cancer and several broad-spectrum, low-molecular-weight MMP inhibitors are currently being assessed for clinical use. This review examines the role of MMPs in tumour invasion and metastasis, with an emphasis on studies of clinical relevance.     

Matrix metalloproteinases: a multifunctional group of molecules

The matrix metalloproteinases are a large group of zinc-containing proteases with a central role in the degradation of all types of extracellular matrix. Increased matrix degradation is a characteristic feature of several disease processes, most notably tumour invasion; it is now widely recognized that this group of proteases has a key role in facilitating invasion and metastasis. However, it is also becoming increasingly recognized that the matrix metalloproteinases are a multifunctional group of biologically important molecules with diverse roles in normal cell growth, differentiation, and cell regulation, and with involvement in the early stages of tumourigenesis. Some of these regulatory functions may be distinct from the matrix-degrading capabilities of this group of enzymes.     

The role of matrilysin (MMP-7) in leukaemia cell invasion

The matrix metalloproteinases (MMPs) are important in tumour cell invasion and metastasis in many common cancers. However, relatively few studies have investigated the role of MMPs and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), in leukaemia cell invasion. This study examined two leukaemia cell lines, K562 and HL-60 and showed that the K562 cell line was four times more invasive than the HL-60 cell line. The expression of MMP-2, matrilysin (MMP-7), MMP-9, TIMP-1, TIMP-2 and TIMP-3 was analysed. Both cell lines produced similar amounts of MMP-2, MMP-9 and TIMP-2. The K562 cells expressed more TIMP-1 than the HL-60 cells and neither cell line expressed TIMP-3. Interestingly, only the K562 cells expressed matrilysin suggesting a potential role for matrilysin in leukaemia cell invasion. In vitro invasion assays performed in the presence of a matrilysin blocking antibody showed a 40% reduction in invasive ability. This data suggests that matrilysin plays an important role in leukaemia cell invasion. This revised version was published online in July 2006 with corrections to the Cover Date.     

Prognostic significance of the molecular markers in human gastrointestinal cancer

Matrix metalloproteinases have been implicated in tumor progression. Matrilysin is one of the matrix metalloproteinases and is frequently overexpressed in gastrointestinal cancers. The aim of this study was to assess the validity of matrilysin as a prognostic marker of colorectal cancers. Matrilysin expression was immunohistochemically analyzed using formalin-fixed, paraffin-embedded specimens from 113 colorectal cancer patients who had undergone curative surgery. The lumenal surface of neoplastic glands in the superficial layer was apically stained, while the cytoplasm of cancer cells at the invasive front was diffusely stained for matrilysin. Sections with immunostaining signals in more than 30% of carcinoma cells at the invasive front, which were observed in 47(42%) cases, were judged as being positive for matrilysin. Matrilysin positivity was significantly correlated with the depth of invasion, lymph node metastasis, lymphatic invasion, advanced Dukes' stage, and poor outcome. Patients with matrilysin-positive cancer had a significantly shorter overall survival time than those with matrilysin-negative cancer. For patients with intermediate invasive tumor(T2 or T3), only matrilysin was a significant prognostic variable for predicting overall survival in multivariate analysis. Matrilysin expression at the invasive front could be an important marker, predicting an unfavorable prognosis after surgical treatment in patients with colorectal cancer.     

Tetraspanins: molecular organisers of the leukocyte surface

Tetraspanins are a large superfamily of cell surface membrane proteins characterised by their four transmembrane domains. They are expressed in a wide variety of cell types and have functional roles in processes, such as cellular adhesion, motility, activation and tumour invasion. Leukocytes express 相似文献   

Involvement of Cdc42 and Rac small G proteins in invadopodia formation of RPMI7951 cells

BACKGROUND: Invadopodia are membrane protrusions into the extracellular matrix by aggressive tumour cells. These structures are associated with sites of matrix degradation and invasiveness of malignant tumour cells in an in vitro fibronectin degradation/invasion assay. The Rho family small G proteins, consisting of the Rho, Rac and Cdc42 subfamilies, are implicated in various cell functions, such as cell shape change, adhesion, and motility, through reorganization of the actin cytoskeleton. We studied the roles of the Rho family small G proteins in invadopodia formation. RESULTS: We first demonstrated that invadopodia of RPMI7951 human melanoma cells extended into the matrix substratum on a vertical view using a laser scanning confocal microscope system. We confirmed that invadopodia were rich in actin filaments (F-actin) and visualized clearly with F-actin staining on a vertical view as well as on a horizontal view. We then studied the roles of Rho, Rac, and Cdc42 in invasiveness of the same cell line. In the in vitro fibronectin degradation/invasion assay, a dominant active mutant of Cdc42 enhanced dot-like degradation, whereas a dominant active mutant of Rac enhanced diffuse-type degradation. Furthermore, frabin, a GDP/GTP exchange protein for Cdc42 with F-actin-binding activity, enhanced both dot-like and diffuse-type degradation. However, a dominant active mutant of Rho did not affect the fibronectin degradation. Moreover, inhibition of phosphatidylinositol-3 kinase (PI3K) disrupted the Rac and Cdc42-dependent actin structures and blocked the fibronectin degradation. CONCLUSION: These results suggest that Cdc42 and Rac play important roles in fibronectin degradation and invasiveness in a coordinate manner through the frabin-Cdc42/Rac-PI3K signalling pathway.     

Association of trypsin expression with tumour progression and matrilysin expression in human colorectal cancer

Overexpression of the matrix serine protease (MSP) trypsin has been implicated in tumour growth, invasion, and metastasis. The objective of this study was to clarify the clinicopathological and prognostic significance of trypsin expression in colorectal cancer. This study analysed the association between immunohistochemically detected trypsin expression in colorectal cancer and clinicopathological characteristics, and investigated whether trypsin is a predictor of recurrence and/or survival. Trypsin immunoreactivity was more intense at the invasive front than in the superficial part of the tumour. Sections with immunostaining signals in more than 30% of carcinoma cells at the invasive front, which were observed in 48 cases (48%), were judged to be positive for trypsin. Trypsin positivity was significantly correlated with depth of invasion, lymphatic and venous invasion, lymph node and distant metastasis, advanced pathological tumour-node-metastasis (TNM) stage, and recurrence. Patients with trypsin-positive carcinoma had significantly shorter overall and disease-free survival periods than did those with trypsin-negative carcinoma. Trypsin retained its significant predictive value for overall and disease-free survival in multivariate analysis that included conventional clinicopathological factors. It is well known that trypsin activates matrilysin (matrix metalloproteinase-7), which plays an important role in colorectal cancer progression. Patients with concordant overexpression of trypsin and matrilysin at the invasive front, in which they were often co-localized, had the worst prognosis. Trypsinogen-1-transfected HCT116 colon cancer cells showed not only trypsin activity, but also active matrilysin activity and were more invasive in vitro than mock-transfected HCT116 cells. These results suggest that trypsin plays a key role in the progression of colorectal cancer. Detection of trypsin expression as well as matrilysin is useful for the prediction of recurrence in and poor prognosis of colorectal cancer patients.     

Fell‐Muir Lecture: Metalloproteinases: from demolition squad to master regulators

Two families of the Metzincin clan of metalloproteinases, the matrix metalloproteinases and the disintegrin metalloproteinases have attracted much attention as important effectors of cellular interactions with their environment. They appear to play significant roles in the modulation of components of the extracellular matrix, matrix and cell receptors, as well as the cytokines and growth factors and their receptors. Such functions at the ‘cutting edge’ of cell biology puts these enzymes in pivotal roles in the orchestration of the rapid response of cells to their environment, acting as key switches between different signalling pathways. Inevitably such enzymes should be regarded as suitable targets for therapeutic approaches to many diseases where such pathways become dysregulated. A major challenge to the development of direct inhibitors of catalysis has been the broad structural similarity of the Metzincin catalytic site. More detailed knowledge of active site structures has helped to some extent to resolve the development of more specific chemical inhibitors and selected enzymes are now being targeted. An alternative strategy is the consideration of the role of the extracatalytic domains that are determinants of specificity at a variety of levels. Dissecting the relationships between structure and function of these interaction sites is allowing the development of new approaches to inhibition of enzyme function. Antibodies are proving useful tools in this respect and may pave the way to a novel biologics approach to disease therapy.     

The Role of Reactive Oxygen Species in Integrin and Matrix Metalloproteinase Expression and Function

Cell adhesion and migration is largely dependent on integrin binding to extracellular matrix, and several signalling pathways involved in these processes have been shown to be modified by reactive oxygen species (ROS). In fact, integrin activation is linked to increased ROS production by NADPH-oxidases, 5-lipoxygenase, and release from mitochondria. Cell migration is intimately linked to degradation of the extracellular matrix, and activated matrix metalloproteinases (MMPs) are a prerequisite for cancer cell invasion and metastasis. In this minireview, we focus on the interplay between integrin-mediated ROS production and MMP expression as well as its biological and pathobiological significance.     

Proteolysis in colorectal cancer.

BACKGROUND: The process of metastasis is complex, involving many interrelated stages, including proteolysis. Proteolysis occurs in both normal and pathological processes and involves the breakdown of the extracellular matrix and/or basement membrane by proteolytic enzymes. Normally, proteolysis is tightly controlled by specific endogenous proteinase inhibitors. However, in certain disease processes, including cancer, controlled but abnormal proteolysis seems to occur. Proteinases involved in tumour invasion and metastasis include the matrix metalloproteinases (MMPs) and the serine proteinases. AIMS: To gain a greater understanding of the proteolytic process occurring in colorectal cancer and to determine which, if any, proteinases are upregulated. METHODS: The synthesis of proteinases and their inhibitors was compared in paired tumour and normal tissue samples from patients with colorectal cancer (n = 24). Substrate zymography was used to determine the synthesis of MMPs (MMP-2, MMP-9, and MMP-3) and the plasminogen activators (urokinase and tissue-type plasminogen activators); enzyme linked immunosorbent assays (ELISAs) were used to determine the concentrations of MMP-1 and tissue inhibitor of metalloproteinase 1 (TIMP-1); and the technique of quenched fluorescence substrate hydrolysis was performed to determine the total MMP activity of each sample. RESULTS: In general, both proteinase and inhibitor expression was greater in the tumour tissue when compared with the corresponding normal colorectal tissue. The amount of active MMPs was greater in the tumour tissue. CONCLUSIONS: The increased extracellular proteinase concentrations and activity may encourage tumour invasion and metastasis. This study points to MMP-9 as being of potential major importance in the development of this form of cancer.     

The role of reactive oxygen species in integrin and matrix metalloproteinase expression and function

Cell adhesion and migration is largely dependent on integrin binding to extracellular matrix, and several signalling pathways involved in these processes have been shown to be modified by reactive oxygen species (ROS). In fact, integrin activation is linked to increased ROS production by NADPH-oxidases, 5-lipoxygenase, and release from mitochondria. Cell migration is intimately linked to degradation of the extracellular matrix, and activated matrix metalloproteinases (MMPs) are a prerequisite for cancer cell invasion and metastasis. In this minireview, we focus on the interplay between integrin-mediated ROS production and MMP expression as well as its biological and pathobiological significance.     

Proteolysis in colorectal cancer.

BACKGROUND: The process of metastasis is complex, involving many interrelated stages, including proteolysis. Proteolysis occurs in both normal and pathological processes and involves the breakdown of the extracellular matrix and/or basement membrane by proteolytic enzymes. Normally, proteolysis is tightly controlled by specific endogenous proteinase inhibitors. However, in certain disease processes, including cancer, controlled but abnormal proteolysis seems to occur. Proteinases involved in tumour invasion and metastasis include the matrix metalloproteinases (MMPs) and the serine proteinases. AIMS: To gain a greater understanding of the proteolytic process occurring in colorectal cancer and to determine which, if any, proteinases are upregulated. METHODS: The synthesis of proteinases and their inhibitors was compared in paired tumour and normal tissue samples from patients with colorectal cancer (n = 24). Substrate zymography was used to determine the synthesis of MMPs (MMP-2, MMP-9, and MMP-3) and the plasminogen activators (urokinase and tissue-type plasminogen activators); enzyme linked immunosorbent assays (ELISAs) were used to determine the concentrations of MMP-1 and tissue inhibitor of metalloproteinase 1 (TIMP-1); and the technique of quenched fluorescence substrate hydrolysis was performed to determine the total MMP activity of each sample. RESULTS: In general, both proteinase and inhibitor expression was greater in the tumour tissue when compared with the corresponding normal colorectal tissue. The amount of active MMPs was greater in the tumour tissue. CONCLUSIONS: The increased extracellular proteinase concentrations and activity may encourage tumour invasion and metastasis. This study points to MMP-9 as being of potential major importance in the development of this form of cancer.     

Expression of functional kappa-opioid receptors on murine dendritic cells

We have shown that two of the matrix metalloproteinases (MMPs), matrilysin and stromelysin-1, are capable of cleaving all of the human IgG subclasses. The cleavage occurs at a conserved site in the CH(2) domain of the heavy chain of IgG, releasing a single chain Fc-like fragment. We have not been able to demonstrate cleavage of IgA, IgD, IgM or IgE classes, which lack the cleavage site, nor could we show cleavage of IgG by collagenase, gelatinase, macrophage metalloelastase or membrane-type (MT)-MMP. This cleavage of IgG, by separating the antigen-binding (Fabprime prime or minute)(2) from the Fc portion, will remove much of the immunoglobulins' functionality, e.g. complement fixation, Fc receptor binding. In the context of a tumour producing matrilysin or stromelysin, this may represent a way in which the tumour protects itself from ADCC. In inflamed or damaged tissues where plasma protein leakage occurs, degradation by MMPs may be a mechanism for clearance of IgG.     

Fluorescence Polarization Assay and SDS-PAGE Confirms Matrilysin Degrades Fibronectin and Collagen IV whereas Gelatinase: A Degrades Collagen IV but not Fibronectin

Matrilysin and gelatinase A are hypothesized to have significant roles in uterine and ovarian function. However, proteolytic activity assays for these enzymes are limited. We describe the development of simple and rapid assays for the proteolysis of fluorescein-labeled full-length substrates, collagen IV (Col-IV) and fibronectin (FN), and demonstrate the selectivity of matrilysin (MMP-7) compared to gelatinase A (MMP-2) for fibronectin. Changes in fluorescence intensity (FIU) and fluorescence polarization (mP) resulting from the protease activity of matrilysin and gelatinase A were measured. These studies show that the fluorescently labeled substrates, Col-IV and FN, are as reliable and amenable to rapid in vitro assay as peptide substrates. In addition, they are easier to use than previously described, non-fluorescent methods. The results demonstrate that assays using full-length, biological matrix proteins are more sensitive indicators of MMP-specific substrate activity than peptide based assays.     

Fluorescence polarization assay and SDS-PAGE confirms matrilysin degrades fibronectin and collagen IV whereas gelatinase A degrades collagen IV but not fibronectin.

Matrilysin and gelatinase A are hypothesized to have significant roles in uterine and ovarian function. However, proteolytic activity assays for these enzymes are limited. We describe the development of simple and rapid assays for the proteolysis of fluorescein-labeled full-length substrates, collagen IV (Col-IV) and fibronectin (FN), and demonstrate the selectivity of matrilysin (MMP-7) compared to gelatinase A (MMP-2) for fibronectin. Changes in fluorescence intensity (FIU) and fluorescence polarization (mP) resulting from the protease activity of matrilysin and gelatinase A were measured. These studies show that the fluorescently labeled substrates, Col-IV and FN, are as reliable and amenable to rapid in vitro assay as peptide substrates. In addition, they are easier to use than previously described, non-fluorescent methods. The results demonstrate that assays using full-length, biological matrix proteins are more sensitive indicators of MMP-specific substrate activity than peptide based assays.     

Role of Cysteine Cathepsins in Matrix Degradation and Cell Signalling

Cysteine cathepsins participate in extracellular matrix (ECM) degradation and remodelling and thus influence important cellular processes such as cell transformation and differentiation, motility, adhesion, invasion, angiogenesis, and metastasis. Also, cathepsins are involved in cell signalling and are capable of activating specific cell receptors and growth factors or liberating them from the ECM. In this review we emphasize recent studies on cathepsins in regard to ECM degradation and cell signalling.     

Role of cysteine cathepsins in matrix degradation and cell signalling

Cysteine cathepsins participate in extracellular matrix (ECM) degradation and remodelling and thus influence important cellular processes such as cell transformation and differentiation, motility, adhesion, invasion, angiogenesis, and metastasis. Also, cathepsins are involved in cell signalling and are capable of activating specific cell receptors and growth factors or liberating them from the ECM. In this review we emphasize recent studies on cathepsins in regard to ECM degradation and cell signalling.     

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.     

Integrins,cadherins, and catenins: molecular cross-talk in cancer cells

In the past decade, there have been major advances in the understanding of some of the mechanisms underlying tumour differentiation, invasion, and metastasis, in which cell–cell and cell–matrix adhesion molecules play a critical role. Cadherin/catenin complex and the integrins are the prime mediators of cell adhesion in normal and transformed cells, cadherin/catenin being largely responsible for intercellular adhesion and integrins for cell–extracellular matrix interactions. Intercellular and cell–matrix adhesion mediated by cadherin/catenin and integrins is likely to play a role in the control of both structural morphology and functional differentiation; hence, any loss of this control mechanism may well facilitate the neoplastic process. Indeed, in cancer cells, there is a co-ordinated down-regulation of both integrins and cadherins which correlates with tumour dedifferentiation. However, the expression and cellular localization of catenins do not always correlate with cadherin expression, since the catenins are rather promiscuous molecules which interact not only with E-cadherin, but also with growth regulatory and signalling molecules such as epidermal growth factor receptor and the adenomatous polyposis coli gene product. © 1998 John Wiley & Sons, Ltd.