Fibrosis and cancer: Do myofibroblasts come also from epithelial cells via EMT?

Myofibroblasts produce and modify the extracellular matrix (ECM), secrete angiogenic and pro-inflammatory factors, and stimulate epithelial cell proliferation and invasion. Myofibroblasts are normally induced transiently during wound healing, but inappropriate induction of myofibroblasts causes organ fibrosis, which greatly enhances the risk of subsequent cancer development. As myofibroblasts are also found in the reactive tumor stroma, the processes involved in their development and activation are an area of active investigation. Emerging evidence suggests that a major source of fibrosis- and tumor-associated myofibroblasts is through transdifferentiation from non-malignant epithelial or epithelial-derived carcinoma cells through epithelial-mesenchymal transition (EMT). This review will focus on the role of EMT in fibrosis, considered in the context of recent studies showing that exposure of epithelial cells to matrix metalloproteinases (MMPs) can lead to increased levels of cellular reactive oxygen species (ROS) that stimulate transdifferentiation to myofibroblast-like cells. As deregulated MMP expression and increased cellular ROS are characteristic of both fibrosis and malignancy, these studies suggest that increased MMP expression may stimulate fibrosis, tumorigenesis, and tumor progression by inducing a specialized EMT in which epithelial cells transdifferentiate into activated myofibroblasts. This connection provides a new perspective on the development of the fibrosis and tumor microenvironments.     

Role of matrix metalloproteinases in melanoma cell invasion

Cutaneous melanomas are notorious for their tendency to metastasize. Essential steps in this process are the degradation of basement membranes and remodeling of the extracellular matrix (ECM) by proteolytic enzymes such as matrix metalloproteinases (MMPs), which are regulated by their tissue inhibitors (TIMPs). An MMP expression is not restricted to tumor cells but is also found in stromal cells, indicating that stroma-derived proteases may contribute to melanoma progression. The MMPs have been shown to interact with a broad range of non-matrix proteins including adhesion molecules, growth factors and mediators of angiogenesis and apoptosis. In this review, we evaluate new insights into the interplay of MMPs and their molecular partners in melanoma progression.     

基质金属蛋白酶家族介绍(英文)

 当细胞外基质 (ECM)组分被破坏时 ,基质金属蛋白酶 (MMPs)影响发育过程并和许多疾病如关节炎及肿瘤相关联 . ECM的正常转换是发育所需要的 . ECM的调节异常却能引起过多的损伤 ,并导致疾病如关节炎 .因此 ,更好地了解 MMP介导的 ECM的水解作用 ,有可能从机理方面为疾病诊断学与治疗学的介入提供依据 .本文介绍了 MMP生物学以及它的 ECM的相关的转换方面的最新进展 .随着新的 MMPs的发现 ,MMP家族正在迅速地扩大 .并且开始向已经确立的基因结构、潜伏期、底物专一性和功能调节方面的范例提出挑战 .即将完成的基因组测序将无容置疑地确定人类 MMPs的有限的数字 .揭示每个 MMP的功能所进行的努力可能标志我们在寻求最终了解细胞与它们的环境之间的相互作用的开始 ,这个过程对于哺乳类物种例如人类的进化是至关重要的 .     

Tissue‐dependent induction of apoptosis by matrix metalloproteinase stromelysin‐3 during amphibian metamorphosis

Matrix metalloproteinases (MMPs) are a superfamily of Zn²⁺‐dependent proteases that are capable of cleaving the proteinaceous component of the extracellular matrix (ECM). The ECM is a critical medium for cell–cell interactions and can also directly signal cells through cell surface ECM receptors, such as integrins. In addition, many growth factors and signaling molecules are stored in the ECM. Thus, ECM remodeling and/or degradation by MMPs are expected to affect cell fate and behavior during many developmental and pathological processes. Numerous studies have shown that the expression of MMP mRNAs and proteins associates tightly with diverse developmental and pathological processes, such as tumor metastasis and mammary gland involution. In vivo evidence to support the roles of MMPs in these processes has been much harder to get. Here, we will review some of our studies on MMP11, or stromelysin‐3, during the thyroid hormone‐dependent amphibian metamorphosis, a process that resembles the so‐called postembryonic development in mammals (from a few months before to several months after birth in humans when organ growth and maturation take place). Our investigations demonstrate that stromelysin‐3 controls apoptosis in different tissues via at least two distinct mechanisms. Birth Defects Research (Part C) 90:55–66, 2010. © 2010 Wiley‐Liss, Inc.     

细胞外基质与基质金属蛋白酶

细胞外基质（ECM）是存在于细胞之间的动态网状结构,由胶原、蛋白聚糖及糖蛋白等大分子物质组成.这些大分子物质可与细胞表面上的特异性受体结合,通过受体与细胞骨架结构直接发生联系或触发细胞内的一系列信号传导而引起不同的基因表达,从而导致细胞的生长和分化.作为降解ECM成分最重要的酶-基质金属蛋白酶（MMPs）及其组织抑制因子(TIMPs)在这一过程中起着非常重要的作用.MMPs是一类依赖金属离子锌并以ECM成分为水解底物的蛋白水解酶.其在转录水平的表达受到生长因子、细胞因子及激素等因素的严格调控,在蛋白质水平其活性也受到其激活剂和抑制剂的调节. MMPs通过对ECM成分的水解来影响其降解与重组的动态平衡而参与多种细胞的生理和病理过程.     

Matrix metalloproteinases and angiogenesis

Matrix metalloproteinases (MMPs) are a family of enzymes that proteolytically degrade various components of the extracellular matrix (ECM). Angiogenesis is the process of forming new blood vessels from existing ones and requires degradation of the vascular basement membrane and remodeling of the ECM in order to allow endothelial cells to migrate and invade into the surrounding tissue. MMPs participate in this remodeling of basement membranes and ECM. However, it has become clear that MMPs contribute more to angiogenesis than just degrading ECM components. Specific MMPs have been shown to enhance angiogenesis by helping to detach pericytes from vessels undergoing angiogenesis, by releasing ECM-bound angiogenic growth factors, by exposing cryptic proangiogenic integrin binding sites in the ECM, by generating promigratory ECM component fragments, and by cleaving endothelial cell-cell adhesions. MMPs can also contribute negatively to angiogenesis through the generation of endogenous angiogenesis inhibitors by proteolytic cleavage of certain collagen chains and plasminogen and by modulating cell receptor signaling by cleaving off their ligand-binding domains. A number of inhibitors of MMPs that show antiangiogenic activity are already in early stages of clinical trials, primarily to treat cancer and cancer-associated angiogenesis. However, because of the multiple effects of MMPs on angiogenesis, careful testing of these MMP inhibitors is necessary to show that these compounds do not actually enhance angiogenesis.     

Matrix metalloproteinases as stromal effectors of human carcinoma progression: Therapeutic implications

The matrix metalloproteinases (MMPs) are extracellular zinc-enzymes implicated in a number of physiological and pathological tissue remodeling processes, including cancer progression. For a long time they have been thought to be produced by malignant cells and to specifically contribute to tumor invasion, through their ability to degrade extracellular matrix components. However, studies performed over the last few years have demonstrated that extracellular proteinases implicated in the progression of human carcinomas, including most MMPs, are in fact predominantly expressed by stromal and not by cancer cells. Furthermore, membrane receptors, activators and/or binding sites for some of these proteinases are also predominantly found to be associated with stromal cells. These findings, together with the observation that MMPs can cleave some molecules implicated in controlling growth factor activities, suggest that the role of MMPs during cancer progression is not limited to facilitating malignant cell invasion alone but is also likely to participate in other aspects of the malignant phenotype. MMPs should in fact be regarded as pan-regulators of tissue neoformation characteristic of malignant tumors, which includes both epithelial cell expansion and stroma formation. In this context, synthetic MMP inhibitors which are presently designed should lead to the development of a new generation of anticancer agents which additional beneficial properties compared to the existing cytotoxic agents used in the treatment of human malignancies.     

Tumor-stroma interaction: positive feedback regulation of extracellular matrix metalloproteinase inducer (EMMPRIN) expression and matrix metalloproteinase-dependent generation of soluble EMMPRIN

Matrix metalloproteinases (MMPs) are metal-dependent endopeptidases that play pivotal roles in tumor disease progression. In many solid tumors, MMPs are indeed produced by tumor stromal cells, rather than by tumor cells. This expression pattern is, at least in part, regulated by tumor-stroma interaction via tumor cell-associated extracellular matrix metalloproteinase inducer (EMMPRIN). In vitro, recombinant EMMPRIN dose-dependently stimulated MMP-1 production by primary human fibroblast cells. Interestingly, in addition to stimulating MMP expression, EMMPRIN also induced its own gene expression. To further explore this potential positive feedback regulatory mechanism, we generated human breast cancer cells expressing different levels of EMMPRIN. Coculture of EMMPRIN-positive tumor cells with fibroblast cells resulted in a concomitant stimulation of MMP-2, MMP-9, and EMMPRIN production. This induction was EMMPRIN dependent, was further enhanced by overexpression, and was reduced by antisense suppression of EMMPRIN expression in tumor cells. Increased expression of membrane-associated EMMPRIN was accompanied by an MMP-dependent generation of a soluble form of EMMPRIN representing a proteolytic cleavage product lacking the carboxyl terminus. On the basis of these findings, we propose a model in which tumor cell-associated EMMPRIN stimulates MMPs, as well as EMMPRIN expression in tumor stroma. Increased MMP activity in tumor local environment results in proteolytic cleavage of membrane-associated EMMPRIN, releasing soluble EMMPRIN. Soluble EMMPRIN in turn acts in a paracrine fashion on stroma cells that are both adjacent and distant to tumor sites to further stimulate the production of MMPs and additional EMMPRIN, which consequently contributes to tumor angiogenesis, tumor growth, and metastasis.     

Extracellular matrix (ECM) stiffness and degradation as cancer drivers

Alteration in the density and composition of extracellular matrix (ECM) occurs in tumors. The alterations toward both stiffness and degradation are contributed to tumor growth and progression. Cancer-associated fibroblasts (CAFs) are the main contributors to ECM stiffness and degradation. The cells interact with almost all cells within the tumor microenvironment (TME) that could enable them to modulate ECM components for tumorigenic purposes. Cross-talks between CAFs with cancer cells and macrophage type 2 (M2) cells are pivotal for ECM stiffness and degradation. CAFs induce hypoxia within the TME, which is one of the key inducers of both stiffness and degradation. Cancer cell modulatory roles in integrin receptors are key for adjusting ECM constituents to either fates. Cancer cell proliferation, migration, and invasion as well as angiogenesis are consequences of ECM stiffness and degradation. ECM stiffness in a transforming growth factor-β (TGF-β) related pathway could make a bridge in the basement membrane, and ECM degradation in a matrix metalloproteinase (MMP)-related pathway could make a path in the TME, both of which contribute to cancer cell invasion. ECM stiffness is also obstructive for drug penetration to the tumor site. Therefore, it would be a promising strategy to make a homeostasis in ECM for easy penetration of chemotherapeutic drugs and increasing the efficacy of antitumor approaches. MMP and TGF-β inhibitors, CAF and M2 reprogramming toward their normal counterparts, reduction of TME hypoxia and hampering integrin signaling are among the promising approaches for the modulation of ECM in favor of tumor regression.     

综述: 细胞外基质与肿瘤相关成纤维细胞

肿瘤的发生发展是一个肿瘤细胞与其微环境相互促进,共同演化的动态过程．实体肿瘤的发生发展过程伴随细胞外基质的过量沉积及其组织形式的异常以及成纤维细胞的活化和富集．细胞外基质与肿瘤相关成纤维细胞不仅是实体肿瘤的重要病理特征,同时也是恶性肿瘤发展的重要驱动力量．细胞外基质与肿瘤相关成纤维细胞通过多种机制促进了肿瘤的发生、发展和转移．针对细胞外基质与肿瘤相关成纤维细胞进行肿瘤治疗,可以为肿瘤的临床治疗提供新的思路．     

Roles of metalloproteases in metastatic niche

Metalloproteinases (MMPs) are a cluster of at least 23 enzymes belonging to the more wide family of endopeptidases called Metzincins, whose structure is characterized by the presence of a zinc ion at the catalytic site. Although the general view of MMPs as physiologic scissors involved in extracellular matrix (ECM) degradation and tissue remodeling is still valid, additional functions have recently emerged, including the ability to cleave non ECM molecules such as growth factors, cytokines and chemokines from their membrane-anchored proforms. These functions are utilized by tumor cells and are fundamental in the determination of tumor progression and invasion. The effect of MMPs activity in cancer progression has been traditionally associated with the acquisition by tumor cells of an invasive phenotype, an indispensable requisite for the metastatic spreading of cancer cells. In addition to the traditional view, a new role for MMPs in creating a favourable microenvironment has been proposed, so that MMPs are not only involved in cell invasion, but also in signaling pathways that control cell growth, inflammation, or angiogenesis. Finally, recent evidence suggest a role of MMPs in the so called "pre-metastatic niche" that is the hypothesis of an early distant modification of the premetastatic site by primary cancer cells. This new hypothesis is changing our traditional view about MMPs and provides important insights into the effective time window for the therapeutic use of MMP inhibitors. In this review we provide the main available data about the ability of MMPs in creating a suitable microenvironment for tumor growth in metastatic sites and we indicate the implication of these data on the potential use of MMP inhibitors in the metastatic therapy.     

MMP Secretion Rate and Inter-invadopodia Spacing Collectively Govern Cancer Invasiveness

Invadopodia are micron-sized invasive structures that mediate extracellular matrix (ECM) degradation through a combination of membrane-bound and soluble matrix metalloproteinases (MMPs). However, how such localized degradation is converted into pores big enough for cancer cells to invade, and the relative contributions of membrane-bound versus soluble MMPs to this process remain unclear. In this article, we address these questions by combining experiments and simulations. We show that in MDA-MB-231 cells, an increase in ECM density enhances invadopodia-mediated ECM degradation and decreases inter-invadopodia spacing. ECM degradation is mostly mediated by soluble MMPs, which are activated by membrane-bound MT1-MMP. We present a computational model of invadopodia-mediated ECM degradation, which recapitulates the above observations and identifies MMP secretion rate as an important regulator of invadopodia stability. Simulations with multiple invadopodia suggest that inter-invadopodia spacing and MMP secretion rate collectively dictate the size of the degraded zones. Taken together, our results suggest that for creating pores conducive for cancer invasion, cells must tune inter-invadopodia spacing and MMP secretion rate in an ECM density-dependent manner, thereby striking a balance between invadopodia penetration and ECM degradation.     

Matrix metalloproteinase-14 is a mechanically regulated activator of secreted MMPs and invasion

Matrix metalloproteinases (MMPs) are extracellular matrix (ECM) degrading enzymes and have complex and specific regulation networks. This includes activation interactions, where one MMP family member activates another. ECM degradation and MMP activation can be initiated by several different stimuli including changes in ECM mechanical properties or intracellular contractility. These mechanical stimuli are known enhancers of metastatic potential. MMP-14 facilitates local ECM degradation and is well known as a major mediator of cell migration, angiogenesis and invasion. Recently, function blocking antibodies have been developed to specifically block MMP-14, providing a useful tool for research as well as therapeutic applications. Here we utilize a selective MMP-14 function blocking antibody to delineate the role of MMP-14 as an activator of other MMPs in response to changes in cellular contractility and ECM stiffness. Inhibition using function blocking antibodies reveals that MMP-14 activates soluble MMPs like MMP-2 and -9 under various mechanical stimuli in the pancreatic cancer cell line, Panc-1. In addition, inhibition of MMP-14 abates Panc-1 cell extension into 3D gels to levels seen with non-specific pan-MMP inhibitors at higher concentrations. This strengthens the case for MMP function blocking antibodies as more potent and specific MMP inhibition therapeutics.     

Matrix metalloproteinase‐3 in the central nervous system: a look on the bright side

Matrix metalloproteinases (MMPs) are a large family of proteases involved in many cell‐matrix and cell‐cell signalling processes through activation, inactivation or release of extracellular matrix (ECM) and non‐ECM molecules, such as growth factors and receptors. Uncontrolled MMP activities underlie the pathophysiology of many disorders. Also matrix metalloproteinase‐3 (MMP‐3) or stromelysin‐1 contributes to several pathologies, such as cancer, asthma and rheumatoid arthritis, and has also been associated with neurodegenerative diseases like Alzheimer's disease, Parkinson's disease and multiple sclerosis. However, based on defined MMP spatiotemporal expression patterns, the identification of novel candidate molecular targets and in vitro and in vivo studies, a beneficial role for MMPs in CNS physiology and recovery is emerging. The main purpose of this review is to shed light on the recently identified roles of MMP‐3 in normal brain development and in plasticity and regeneration after CNS injury and disease. As such, MMP‐3 is correlated with neuronal migration and neurite outgrowth and guidance in the developing CNS and contributes to synaptic plasticity and learning in the adult CNS. Moreover, a strict spatiotemporal MMP‐3 up‐regulation in the injured or diseased CNS might support remyelination and neuroprotection, as well as genesis and migration of stem cells in the damaged brain.     

Expression of the extracellular matrix metalloproteinase inducer (EMMPRIN) and the matrix metalloproteinase-2 in bronchopulmonary and breast lesions.

Tumor cells interact with stromal cells via soluble or cell-bound factors stimulating the production of matrix metalloproteinases (MMPs), a group of enzymes largely involved in the extracellular matrix (ECM) remodeling in tumor invasion. Among these factors, extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to stimulate in vitro the fibroblast production of various MMPs such as interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), and gelatinase A (MMP-2). In this study, the EMMPRIN protein was detected by immunohistochemistry prominently in malignant proliferations of the breast and the lung. It was present at the surface of both tumor epithelial and peritumor stromal cells. Because previous studies have reported that stromal cells do not express EMMPRIN mRNAs, it is very likely that EMMPRIN is bound to stromal cells via a specific receptor. Moreover, our observations also demonstrated that the same peritumor stromal cells strongly express MMP-2. Our results show that EMMPRIN is an important factor in tumor progression by causing tumor-associated stromal cells to increase their MMP-2 production, thus facilitating tumor invasion and neoangiogenesis. (J Histochem Cytochem 47: 1575-1580, 1999)     

Ontogeny and regulation of matrix metalloproteinase activity in the zebrafish embryo by in vitro and in vivo zymography

Remodeling of the extracellular matrix (ECM) during development, angiogenesis, wound healing, tumor metastasis, and other morphogenetic processes depends on the exquisitely regulated activities of matrix metalloproteinases (MMPs). Yet very little is known about the activity patterns of these proteases in vivo. We have employed fluorescent MMP-substrates, both in vitro and in vivo, to characterize patterns of MMP activity in the zebrafish embryo. Qualitatively similar patterns of degradation are detected using native Type I or Type IV collagen substrates, suggesting that multiple MMPs are being regulated concomitantly. MMP activity is observed primarily in ECM-rich structures predicted to be undergoing active remodeling, such as the perichordal sheath and somite boundaries. Patterns of Type I and Type IV collagen hydrolysis are similar, but not identical in embryos of any given stage. Conventional gelatin zymography shows MMPs present in embryos as early as 3-somites (11 h) and our in vivo assays detect Type IV collagen degradation at somite boundaries as early as 4-somites (11.5 h). However, we are unable to detect significant in vitro activity using homogenates made from embryos prior to Prim-16 (31 h). Mixed lysate assays demonstrate that this is the result of endogenous inhibitors present in early embryos, suggesting a model of matrix remodeling regulated by spatially heterogeneous MMP inhibition.