In vivo evidence that the stromelysin-3 metalloproteinase contributes in a paracrine manner to epithelial cell malignancy

MMP-11 expression in early luminal breast cancer: associations with clinical, MRI, pathological characteristics, and disease-free survival

BACKGROUND

Early hormone-positive breast cancers typically have favorable outcomes, yet long-term surveillance is crucial due to the risk of late recurrences. While many studies associate MMP-11 expression with poor prognosis in breast cancer, few focus on early-stage cases. This study explores MMP-11 as an early prognostic marker in hormone-positive breast cancers.

METHODS

In this retrospective study, 228 women with early hormone-positive invasive ductal carcinoma, treated surgically between 2011 and 2016, were included. MMP-11 expression was measured by immunohistochemistry, and its association with clinical and MRI data was analyzed.

RESULTS

Among the patients (aged 31-89, median 60, with average tumor size of 15.7 mm), MMP-11 staining was observed in half of the cases. This positivity correlated with higher uPA levels and tumor grade but not with nodal status or size. Furthermore, MMP-11 positivity showed specific associations with MRI features. Over a follow-up period of 6.5 years, only 12 oncological events occurred. Disease-free survival was linked to Ki67 and MMP-11.

CONCLUSION

MMP-11, primarily present in tumor-surrounding stromal cells, correlates with tumor grade and uPA levels. MMP-11 immunohistochemical score demonstrates a suggestive trend in association with disease-free survival, independent of Ki67 and other traditional prognostic factors. This highlights the potential of MMP-11 as a valuable marker in managing early hormone-positive breast cancer.

Matrix metalloproteinase 1 is a poor prognostic biomarker for patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains an incurable malignancy despite the treatment methods being continually updated. Matrix metalloproteinases (MMPs) promote the progression of HCC; however, no consensus exists on which MMP plays the predominant role in HCCs. In the present study, we analyzed differentially expressed genes in HCCs, especially MMPs, compared with adjacent tissues using the Cancer Genome Atlas database. The KEGG enrichment pathway using differentially expressed genes included extracellular matrix-receptor interaction, which was correlated with MMPs. We found that among the MMP family, only MMP1, MMP3, MMP8, MMP9, MMP11, MMP12, MMP14, MMP15, MMP20, MMP21, and MMP24 significantly increased in HCCs compared with adjacent tissues. Crucially, survival and univariate analyses indicated that only MMPs 1, 9, 12, and 14 predict poor overall survival; however, multivariate Cox analysis and a nomogram demonstrated that only MMP1 is a poor prognostic biomarker for HCCs. In addition, we observed significant enrichment of uncharacterized cells but decreased macrophages in HCC tissues. Consistent with decreased macrophages in HCCs, MMP1 was negatively associated with macrophages but positively correlated with uncharacterized cells, indicating that the main producer of MMP1 is uncharacterized cells. Furthermore, MMP1 expression was negatively correlated with immune responses of HCCs. Taken together, our findings indicated that MMP1 is a poor and predominant prognostic biomarker for patients with HCC and that anti-MMP1 may be a novel therapy that is worth studying in depth.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

Metalloproteases in gonad formation and ovulation

Changes in expression or activation of various metalloproteases including matrix metalloproteases (Mmp), a disintegrin and metalloprotease (Adam) and a disintegrin and metalloprotease with thrombospondin motif (Adamts), and their endogenous inhibitors (tissue inhibitors of metalloproteases, Timp), have been shown to be critical for ovulation in various species from studies in past decades. Some of these metalloproteases such as Adamts1, Adamts9, Mmp2, and Mmp9 have also been shown to be regulated by luteinizing hormone (LH) and/or progestin, which are essential triggers for ovulation in all vertebrate species. Most of these metalloproteases also express broadly in various tissues and cells including germ cells and somatic gonad cells. Thus, metalloproteases likely play roles in gonad formation processes comprising primordial germ cell (PGC) migration, development of germ and somatic cells, and sex determination. However, our knowledge on the functions and mechanisms of metalloproteases in these processes in vertebrates is still lacking. This review will summarize our current knowledge on the metalloproteases in ovulation and gonad formation with emphasis on PGC migration and germ cell development.

Paralogues of Mmp11 and Timp4 Interact during the Development of the Myotendinous Junction in the Zebrafish Embryo

The extracellular matrix (ECM) of the myotendinous junction (MTJ) undergoes dramatic physical and biochemical remodeling during the first 48 h of development in zebrafish, transforming from a rectangular fibronectin-dominated somite boundary to a chevron-shaped laminin-dominated MTJ. Matrix metalloproteinase 11 (Mmp11, a.k.a. Stromelysin-3) is both necessary and sufficient for the removal of fibronectin at the MTJ, but whether this protease acts directly on fibronectin and how its activity is regulated remain unknown. Using immunofluorescence, we show that both paralogues of Mmp11 accumulate at the MTJ during this time period, but with Mmp11a present early and later replaced by Mmp11b. Moreover, Mmp11a also accumulates intracellularly, associated with the Z-discs of sarcomeres within skeletal muscle cells. Using the epitope-mediated MMP activation (EMMA) assay, we show that despite having a weaker paired basic amino acid motif in its propeptide than Mmp11b, Mmp11a is activated by furin, but may also be activated by other mechanisms intracellularly. One or both paralogues of tissue inhibitors of metalloproteinase-4 (Timp4) are also present at the MTJ throughout this process, and yeast two-hybrid assays reveal distinct and specific interactions between various domains of these proteins. We propose a model in which Mmp11a activity is modulated (but not inhibited) by Timp4 during early MTJ remodeling, followed by a phase in which Mmp11b activity is both inhibited and spatially constrained by Timp4 in order to maintain the structural integrity of the mature MTJ.

The Versatile Role of Matrix Metalloproteinase for the Diverse Results of Fibrosis Treatment

Fibrosis is a type of chronic organ failure, resulting in the excessive secretion of extracellular matrix (ECM). ECM protects wound tissue from infection and additional injury, and is gradually degraded during wound healing. For some unknown reasons, myofibroblasts (the cells that secrete ECM) do not undergo apoptosis; this is associated with the continuous secretion of ECM and reduced ECM degradation even during de novo tissue formation. Thus, matrix metalloproteinases (MMPs) are considered to be a potential target of fibrosis treatment because they are the main groups of ECM-degrading enzymes. However, MMPs participate not only in ECM degradation but also in the development of various biological processes that show the potential to treat diseases such as stroke, cardiovascular diseases, and arthritis. Therefore, treatment involving the targeting of MMPs might impede typical functions. Here, we evaluated the links between these MMP functions and possible detrimental effects of fibrosis treatment, and also considered possible approaches for further applications.

Consequences of EMT-Driven Changes in the Immune Microenvironment of Breast Cancer and Therapeutic Response of Cancer Cells

Epithelial-to-mesenchymal transition (EMT) is a process through which epithelial cells lose their epithelial characteristics and cell–cell contact, thus increasing their invasive potential. In addition to its well-known roles in embryonic development, wound healing, and regeneration, EMT plays an important role in tumor progression and metastatic invasion. In breast cancer, EMT both increases the migratory capacity and invasive potential of tumor cells, and initiates protumorigenic alterations in the tumor microenvironment (TME). In particular, recent evidence has linked increased expression of EMT markers such as TWIST1 and MMPs in breast tumors with increased immune infiltration in the TME. These immune cells then provide cues that promote immune evasion by tumor cells, which is associated with enhanced tumor progression and metastasis. In the current review, we will summarize the current knowledge of the role of EMT in the biology of different subtypes of breast cancer. We will further explore the correlation between genetic switches leading to EMT and EMT-induced alterations within the TME that drive tumor growth and metastasis, as well as their possible effect on therapeutic response in breast cancer.

The Role of Ceramide 1-Phosphate in Tumor Cell Survival and Dissemination

Ceramide 1-phosphate (C1P) is a pleiotropic bioactive sphingolipid metabolite capable of regulating key physiologic cell functions and promoting pathologic processes. Concerning pathology, C1P or ceramide kinase (CerK), the enzyme responsible for its biosynthesis in mammalian cells, has been implicated in cancer cell growth, survival, and dissemination and is involved in inflammatory responses associated with different types of cancer cells. The mechanisms or signaling pathways mediating these C1P actions have only been partially described. This chapter reviews recent progress in identifying signal transduction pathways involved in the promotion of cancer cell growth, survival, and dissemination by CerK and C1P.

Therapeutic Potential of Matrix Metalloproteinase Inhibition in Breast Cancer

Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that cleave nearly all components of the extracellular matrix as well as many other soluble and cell-associated proteins. MMPs have been implicated in normal physiological processes, including development, and in the acquisition and progression of the malignant phenotype. Disappointing results from a series of clinical trials testing small molecule, broad spectrum MMP inhibitors as cancer therapeutics led to a re-evaluation of how MMPs function in the tumor microenvironment, and ongoing research continues to reveal that these proteins play complex roles in cancer development and progression. It is now clear that effective targeting of MMPs for therapeutic benefit will require selective inhibition of specific MMPs. Here, we provide an overview of the MMP family and its biological regulators, the tissue inhibitors of metalloproteinases (TIMPs). We then summarize recent research from model systems that elucidate how specific MMPs drive the malignant phenotype of breast cancer cells, including acquisition of cancer stem cell features and induction of the epithelial-mesenchymal transition, and we also outline clinical studies that implicate specific MMPs in breast cancer outcomes. We conclude by discussing ongoing strategies for development of inhibitors with therapeutic potential that are capable of selectively targeting the MMPs most responsible for tumor promotion, with special consideration of the potential of biologics including antibodies and engineered proteins based on the TIMP scaffold. J. Cell. Biochem. 118: 3531-3548, 2017. © 2017 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc.

Matrix metalloproteinase 11 protects from diabesity and promotes metabolic switch

MMP11 overexpression is a bad prognostic factor in various human carcinomas. Interestingly, this proteinase is not expressed in malignant cells themselves but is secreted by adjacent non-malignant mesenchymal/stromal cells, such as cancer associated fibroblasts (CAFs) and adipocytes (CAAs), which favors cancer cell survival and progression. As MMP11 negatively regulates adipogenesis in vitro, we hypothesized that it may play a role in whole body metabolism and energy homeostasis. We used an in vivo gain- (Mmp11-Tg mice) and loss- (Mmp11−/− mice) of-function approach to address the systemic function of MMP11. Strikingly, MMP11 overexpression protects against type 2 diabetes while Mmp11−/− mice exhibit hallmarks of metabolic syndrome. Moreover, Mmp11-Tg mice were protected from diet-induced obesity and display mitochondrial dysfunction, due to oxidative stress, and metabolic switch from oxidative phosphorylation to aerobic glycolysis. This Warburg-like effect observed in adipose tissues might provide a rationale for the deleterious impact of CAA-secreted MMP11, favouring tumor progression. MMP11 overexpression also leads to increased circulating IGF1 levels and the activation of the IGF1/AKT/FOXO1 cascade, an important metabolic signalling pathway. Our data reveal a major role for MMP11 in controlling energy metabolism, and provide new clues for understanding the relationship between metabolism, cancer progression and patient outcome.

Insights into the distinct roles of MMP-11 in tumor biology and future therapeutics (Review)

The biological processes of cancer cells such as tumorigenesis, proliferation, angiogenesis, apoptosis and invasion are greatly influenced by the surrounding microenvironment. The ability of solid malignant tumors to alter the microenvironment represents an important characteristic through which tumor cells are able to acquire specific functions necessary for their malignant biological behaviors. Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases with the capacity of remodeling extracellular matrix (ECM) by degrading almost all ECM proteins, which plays essential roles during the invasion and metastasis process of solid malignant tumors, including allowing tumor cells to modify the ECM components and release cytokines, ultimately facilitating protease-dependent tumor progression. MMP-11, also named stromelysin-3, is a member of the stromelysin subgroup belonging to MMPs superfamily, which has been detected in cancer cells, stromal cells and adjacent microenvironment. Differently, MMP-11 exerts a dual effect on tumors. On the one hand MMP-11 promotes cancer development by inhibiting apoptosis as well as enhancing migration and invasion of cancer cells, on the other hand MMP-11 plays a negative role against cancer development via suppressing metastasis in animal models. Overexpression of MMP-11 was discovered in sera of cancer patients compared with normal control group as well as in multiple tumor tissue specimens, such as gastric cancer, breast cancer, and pancreatic cancer. At present, some evidence supports that MMP-11 may work as a significant tumor biomarker for early detection of cancer, tumor staging, prognostic analysis, monitoring recurrence during follow-up and also a potential target for immunotherapy against cancer. In view of the importance of MMP-11 in modifying tumor microenvironment and potent antitumoral effects on solid tumors, there is an urgent need for a deeper understanding of how MMP-11 modulates tumor progression, and exploring its potential clinical application.

Matrix metalloproteinase-11 as a marker of metastasis and predictor of poor survival in urothelial carcinomas

BACKGROUND AND OBJECTIVES

Urothelial carcinomas (UC) of urinary bladder (UB) and upper urinary tract (UT) are heterogeneous diseases with high morbidity and mortality. We looked for genes with metalloendopeptidase activity in a published UBUC transcriptomic database (GSE31684):MMP-11 was the most significant, showing stepwise up-regulation. We analyzed MMP-11 expression and association with clinicopathologic factors and survival in our well-characterized cohort of UCs.

METHODS

We determined MMP-11 expression in 295 UBUCs and 340 UTUCs with immunohistochemistry, evaluated by H-score. In a retrospective study, MMP-11 expression was correlated with clinicopathologic features and with disease-specific survival (DSS) and metastasis-free survival (MeFS). The statistical significance was evaluated with univariate and multivariate analyses.

RESULTS

High MMP-11 expression was significantly associated with advanced pT status, nodal metastasis, high histological grade, vascular and perineural invasion, and frequent mitoses. In multivariate Cox regression analyses, which adjusted for standard clinicopathologic characteristics, MMP-11 expression was independently associated with cancer-specific mortality (hazard ratio [HR] in UTUC:3.027, P = 0.005; in UBUC: 2.631, P = 0.010) and with metastasis development (HR in UTUC:2.261, P = 0.018; in UBUC:1.801, P = 0.026).

CONCLUSIONS

MMP-11 overexpression is associated with aggressive tumor phenotype and unfavorable clinical outcome in UTUC and UBUC, suggesting it may serve as a novel prognostic and therapeutic target. J. Surg. Oncol. 2016;113:700-707. © 2016 Wiley Periodicals, Inc.

ESR1 mutations—a mechanism for acquired endocrine resistance in breast cancer

Approximately 70% of breast cancers are oestrogen receptor α (ER) positive, and are, therefore, treated with endocrine therapies. However, about 25% of patients with primary disease and almost all patients with metastases will present with or eventually develop endocrine resistance. Despite the magnitude of this clinical challenge, the mechanisms underlying the development of resistance remain largely unknown. In the past 2 years, several studies unveiled gain-of-function mutations in ESR1, the gene encoding the ER, in approximately 20% of patients with metastatic ER-positive disease who received endocrine therapies, such as tamoxifen and aromatase inhibitors. These mutations are clustered in a 'hotspot' within the ligand-binding domain (LBD) of the ER and lead to ligand-independent ER activity that promotes tumour growth, partial resistance to endocrine therapy, and potentially enhanced metastatic capacity; thus, ER LBD mutations might account for a mechanism of acquired endocrine resistance in a substantial fraction of patients with metastatic disease. In general, the absence of detectable ESR1 mutations in patients with treatment-naive disease, and the correlation between the frequency of patients with tumours harbouring these mutations and the number of endocrine treatments received suggest that, under selective treatment pressure, clonal expansion of rare mutant clones occurs, leading to resistance. Preclinical and clinical development of rationale-based novel therapeutic strategies that inhibit these ER mutants has the potential to substantially improve treatment outcomes. We discuss the contribution of ESR1 mutations to the development of acquired resistance to endocrine therapy, and evaluate how mutated ER can be detected and targeted to overcome resistance and improve patient outcomes.

Matrix metalloproteinases and genetic mouse models in cancer research: a mini-review

Carcinogenesis is a multistep and also a multifactorial process that involves agents like genetic and environmental factors. Matrix metalloproteinases (MMPs) are major proteolytic enzymes which are involved in cancer cell migration, invasion, and metastasis. Genetic variations in genes encoding the MMPs were shown in human studies to influence cancer risk and phenotypic features of a tumor. The complex role of MMPs seems to be important in the mechanism of carcinogenesis, but it is not well recognized. Rodent studies concentrated particularly on the better understanding of the biological functions of the MMPs and their impact on the pathological process, also through the modification of Mmp genes. This review presents current knowledge and the existing evidence on the importance of selected MMPs in genetic mouse models of cancer and human genetic association studies. Further, this work can be useful for scientists studying the role of the genetic impact of MMPs in carcinogenesis.

Matrix metalloproteinases in inflammation

BACKGROUND

Matrix metalloproteinases (MMPs) are a family of ubiquitously expressed zinc-dependent endopeptidases with broad substrate specificity and strictly regulated tissue specific expression. They are expressed in physiological situations and pathological conditions involving inflammation. MMPs regulate several functions related to inflammation including bioavailability and activity of inflammatory cytokines and chemokines. There is also evidence that MMPs regulate inflammation in tumor microenvironment, which plays an important role in cancer progression.

SCOPE OF REVIEW

Here, we discuss the current view on the role of MMPs in the regulation of inflammation.

MAJOR CONCLUSIONS

MMPs modulate inflammation by regulating bioavailability and activity of cytokines, chemokines, and growth factors, as well as integrity of physical tissue barriers. MMPs are also involved in immune evasion of tumor cells and in regulation of inflammation in tumor microenvironment.

GENERAL SIGNIFICANCE

There is increasing evidence for non-matrix substrates of MMPs that are related to regulation of inflammatory processes. New methods have been employed for identification of the substrates of MMPs in inflammatory processes in vivo. Detailed information on the substrates of MMPs may offer more specific and effective ways of inhibiting MMP function by blocking the cleavage site in substrate or by inhibition of the bioactivity of the substrate. It is expected, that more precise information on the MMP-substrate interaction may offer novel strategies for therapeutic intervention in inflammatory diseases and cancer without blocking beneficial actions of MMPs. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Insidious changes in stromal matrix fuel cancer progression

Reciprocal interactions between tumor and stromal cells propel cancer progression and metastasis. A complete understanding of the complex contributions of the tumor stroma to cancer progression necessitates a careful examination of the extracellular matrix (ECM), which is largely synthesized and modulated by cancer-associated fibroblasts. This structurally supportive meshwork serves as a signaling scaffold for a myriad of biologic processes and responses favoring tumor progression. The ECM is a repository for growth factors and cytokines that promote tumor growth, proliferation, and metastasis through diverse interactions with soluble and insoluble ECM components. Growth factors activated by proteases are involved in the initiation of cell signaling pathways essential to invasion and survival. Various transmembrane proteins produced by the cancer stroma bind the collagen and fibronectin-rich matrix to induce proliferation, adhesion, and migration of cancer cells, as well as protease activation. Integrins are critical liaisons between tumor cells and the surrounding stroma, and with their mechano-sensing ability, induce cell signaling pathways associated with contractility and migration. Proteoglycans also bind and interact with various matrix proteins in the tumor microenvironment to promote cancer progression. Together, these components function to mediate cross-talk between tumor cells and fibroblasts ultimately to promote tumor survival and metastasis. These stromal factors, which may be expressed differentially according to cancer stage, have prognostic utility and potential. This review examines changes in the ECM of cancer-associated fibroblasts induced through carcinogenesis, and the impact of these changes on cancer progression. The implication is that cancer progression, even in epithelial cancers, may be based in large part on changes in signaling from cancer-associated stromal cells. These changes may provide early prognostic indicators to further stratify patients during treatment or alter the timing of their follow-up visits and observations.

Stromal matrix metalloproteinase-11 is involved in the mammary gland postnatal development

MMP-11 is a bad prognosis paracrine factor in invasive breast cancers. However, its mammary physiological function remains largely unknown. In the present study we have investigated MMP-11 function during postnatal mammary gland development and function using MMP-11-deficient (MMP-11-/-) mice. Histological and immunohistochemical analyses as well as whole-mount mammary gland staining show alteration of the mammary gland in the absence of MMP-11, where ductal tree, alveolar structures and milk production are reduced. Moreover, a series of transplantation experiments allowed us to demonstrate that MMP-11 exerts an essential local paracrine function that favors mammary gland branching and epithelial cell outgrowth and invasion through adjacent connective tissues. Indeed, MMP-11-/- cleared fat pads are not permissive for wild-type epithelium development, whereas MMP-11-/- epithelium transplants grow normally when implanted in wild-type cleared fat pads. In addition, using primary mammary epithelial organoids, we show in vitro that this MMP-11 pro-branching effect is not direct, suggesting that MMP-11 acts via production/release of stroma-associated soluble factor(s). Finally, the lack of MMP-11 leads to decreased periductal collagen content, suggesting that MMP-11 has a role in collagen homeostasis. Thus, local stromal MMP-11 might also regulate mammary epithelial cell behavior mechanically by promoting extracellular matrix stiffness. Collectively, the present data indicate that MMP-11 is a paracrine factor involved during postnatal mammary gland morphogenesis, and support the concept that the stroma strongly impact epithelial cell behavior. Interestingly, stromal MMP-11 has previously been reported to favor malignant epithelial cell survival and promote cancer aggressiveness. Thus, MMP-11 has a paracrine function during mammary gland development that might be harnessed to promote tumor progression, exposing a new link between development and malignancy.

Chemokine receptor expression on integrin-mediated stellate projections of prostate cancer cells in 3D culture

The chemokine receptor CXCR7 has emerged as a regulator of prostate tumor growth and invasion, along with the well-established role of its closely related receptor, CXCR4, and their shared ligand, SDF-1α. Consequently, inhibition of the CXCR7/CXCR4/SDF-1α axis may assist in controlling prostate tumor growth and progression. To facilitate the development of potential therapeutics, further clarification of CXCR7 function is required, specifically in relation to CXCR4. In this study, we report that CXCR7 and CXCR4 were co-expressed in LNCaP, DU145 and PC3 cell lines in 2D culture. When cultured in 3D using Matrigel, a marked up-regulation of both receptors was observed in PC3 cells. Interestingly, both CXCR7 and CXCR4 co-localized within radiating cellular structures, termed stellate projections, which protruded outward into the matrix. The stellate projections were rich in the expression of pro-invasive integrin β1, β-laminin and MMP-11 proteins. The development of the stellate projections was mediated by integrin β1-mediated interactions with the ECM, which also regulated the expression of CXCR7 and CXCR4. Taken together, these results demonstrate that integrin-mediated cell-ECM interactions can modulate tumor cell morphology, and regulate the expression of chemokine receptors which are associated with the invasive phenotype and progression of PCa.

Distinct and atypical intrinsic and extrinsic cell death pathways between photoreceptor cell types upon specific ablation of Ranbp2 in cone photoreceptors

Non-autonomous cell-death is a cardinal feature of the disintegration of neural networks in neurodegenerative diseases, but the molecular bases of this process are poorly understood. The neural retina comprises a mosaic of rod and cone photoreceptors. Cone and rod photoreceptors degenerate upon rod-specific expression of heterogeneous mutations in functionally distinct genes, whereas cone-specific mutations are thought to cause only cone demise. Here we show that conditional ablation in cone photoreceptors of Ran-binding protein-2 (Ranbp2), a cell context-dependent pleiotropic protein linked to neuroprotection, familial necrotic encephalopathies, acute transverse myelitis and tumor-suppression, promotes early electrophysiological deficits, subcellular erosive destruction and non-apoptotic death of cones, whereas rod photoreceptors undergo cone-dependent non-autonomous apoptosis. Cone-specific Ranbp2 ablation causes the temporal activation of a cone-intrinsic molecular cascade highlighted by the early activation of metalloproteinase 11/stromelysin-3 and up-regulation of Crx and CoREST, followed by the down-modulation of cone-specific phototransduction genes, transient up-regulation of regulatory/survival genes and activation of caspase-7 without apoptosis. Conversely, PARP1⁺-apoptotic rods develop upon sequential activation of caspase-9 and caspase-3 and loss of membrane permeability. Rod photoreceptor demise ceases upon cone degeneration. These findings reveal novel roles of Ranbp2 in the modulation of intrinsic and extrinsic cell death mechanisms and pathways. They also unveil a novel spatiotemporal paradigm of progression of neurodegeneration upon cell-specific genetic damage whereby a cone to rod non-autonomous death pathway with intrinsically distinct cell-type death manifestations is triggered by cell-specific loss of Ranbp2. Finally, this study casts new light onto cell-death mechanisms that may be shared by human dystrophies with distinct retinal spatial signatures as well as with other etiologically distinct neurodegenerative disorders.

The secondary demise of healthy neurons upon the degeneration of neurons harboring primary genetic defect(s) is hallmark to neurodegenerative diseases. However, the factors and mechanisms driving these cell-death processes are not understood, a severe limitation which has hampered the therapeutic development of neuroprotective approaches. The neuroretina is comprised of two main types of photoreceptor neurons, rods and cones. These undergo degeneration upon heterogeneous mutations or environmental stressors and the underlying diseases present conspicuous spatiotemporal pathological signatures whose molecular bases are not understood. We employed the multifunctional protein, Ran-binding protein-2 (Ranbp2), which is implicated in cell-type and stress-dependent clinical manifestations, to examine its role(s) in primary and secondary photoreceptor death mechanisms upon its specific loss in cones. Contrary to prior findings, we found that dying cones can trigger the loss of healthy rods. This process arises by the immediate activation of novel Ranbp2-responsive factors and downstream cascade events in cones that promote extrinsically the demise of rods. The mechanisms of rod and cone demise are molecularly distinct. Collectively, the data uncover distinct Ranbp2 roles in intrinsic and extrinsic cell-death and will likely contribute to our understanding of the spatiotemporal onset and progression of diseases affecting photoreceptor mosaics and other neural networks.

The role of the tumor microenvironment in regulating angiogenesis

The tumor-associated stroma has been shown to play a significant role in cancer formation. Paracrine signaling interactions between epithelial tumor cells and stromal cells are a key component in the transformation and proliferation of tumors in several organs. Whereas the intracellular signaling pathways regulating the expression of several pro- and antiangiogenic proteins have been well characterized in human cancer cells, the intercellular signaling that takes place between tumor cells and the surrounding tumor-associated stroma has not been as extensively studied with regard to the regulation of angiogenesis. In this chapter we define the key players in the regulation of angiogenesis and examine how their expression is regulated in the tumor-associated stroma. The resulting analysis is often seemingly paradoxical, underscoring the complexity of intercellular signaling within tumors and the need to better understand the environmental context underlying these signaling mechanisms.

A single nucleotide polymorphism in the matrix metalloproteinase 2 promoter is closely associated with high risk of nasopharyngeal carcinoma in Cantonese from southern China

Matrix metalloproteinase 2 (MMP2) has been shown to play an important role in several steps of cancer development. The -1306C/T polymorphism of the MMP2 gene displays a strikingly lower promoter activity than the T allele, and the CC genotype in the MMP2 promoter has been reported to associate with the development of several cancers. To assess the contribution of the MMP2 -1306C/T polymorphism to the risk of nasopharyngeal carcinoma (NPC), we conducted a case-control study and analyzed MMP2 genotypes in 370 patients with NPC and 390 frequency-matched controls using real-time PCR-based TaqMan allele analysis. We found that subjects with the CC genotype had an increased risk (OR = 1.55, 95% CI = 1.05-2.27) of developing NPC compared to those with the CT or TT genotypes. Furthermore, we found that the risk of NPC was markedly increased in subjects who were smokers (OR = 15.04, 95% CI = 6.65-33.99), heavy smokers who smoked ≥20 pack-years (OR = 18.66, 95% CI = 7.67-45.38), or young (<60 years) at diagnosis (OR = 1.52, 95% CI = 1.01-2.29). Our results provide molecular epidemiological evidence that the MMP2 –1306C/T promoter polymorphism is associated with NPC risk, and this association is especially noteworthy in heavy smokers.

Diagnostic and prognostic relevance of MMP-11 expression in the stromal fibroblast-like cells adjacent to invasive ductal carcinoma of the breast

BACKGROUND

Matrix metalloproteinase 11 (MMP-11) is a matrix degrading enzyme known to be involved in the remodeling of extracellular matrix proteins. This enzyme recently has been reported to play a key role in tumor progression and results in poor clinical outcomes for several different types of tumors.

METHODS

A total of 192 patients diagnosed with invasive ductal carcinoma between 2000 and 2005 were included in this study. MMP-11 expression in tumors and stromal fibroblast-like cells was analyzed by immunohistochemical staining on a tissue microarray. Subsequently, evaluation of the associations between MMP-11 expression and clinicopathological characteristics was performed.

RESULTS

MMP-11 expression of stromal fibroblast-like cells was correlated with prognostic factors, including tumor size, metastasis, histological grade, central tumor fibrosis, p53 expression, and luminal A subtype and was linked to therapeutic markers, such as ER and HER2 (all p < 0.05). There was a significant relationship between worse overall survival and MMP-11 expression in both tumors and stromal fibroblast-like cells (all p < 0.05). In multivariate analysis, MMP-11 expression of stromal fibroblast-like cells was still significantly associated with poor prognosis (p = 0.043).

CONCLUSIONS

MMP-11 expression was significantly related to clinicopathological parameters, which may be essential to the prediction of disease outcome in patients with invasive ductal carcinoma of the breast.

Extra- and intracellular imaging of human matrix metalloprotease 11 (hMMP-11) with a cell-penetrating FRET substrate

Matrix metalloprotease 11 (MMP-11), a protease associated with invasion and aggressiveness of cancerous tissue, was postulated as a prognostic marker for pancreatic, breast, and colon cancer patients. Expression analysis, however, did not reveal localization and regulation of this protease. Thus, cellular tools for the visualization of MMP-11 are highly desirable to monitor presence and activity and to elucidate the functional role of MMP-11. Therefore, fluorescein-Dabcyl-labeled Foerster resonance energy transfer (FRET) substrates were developed. The design focused on enhanced peptide binding to human MMP-11, employing an unusual amino acid for the specificity pocket P1'. The addition of several arginines resulted in a cell-permeable FRET substrate SM-P124 (Ac-GRRRK(Dabcyl)-GGAANC(MeOBn)RMGG-fluorescein). In vitro evaluation of SM-P124 with human MMP-11 showed a 25-fold increase of affinity (k(cat)/K(m) = 9.16 × 10(3) m(-1) s(-1), K(m) = 8 μm) compared with previously published substrates. Incubation of pancreatic adenocarcinoma cell line MIA PaCa-2 and mamma adenocarcinoma cell line MCF-7 with the substrate SM-P124 (5 μm) indicated intra- and extracellular MMP-11 activity. A negative control cell line (Jurkat) showed no fluorescent signal either intra- or extracellularly. Negative control FRET substrate SM-P123 produced only insignificant extracellular fluorescence without any intracellular fluorescence. SM-P124 therefore enabled intra- and extracellular tracking of MMP-11-overexpressing cancers such as pancreatic and breast adenocarcinoma and might contribute to the understanding of the activation pathways leading to MMP-11-mediated invasive processes.

Let-7c functions as a metastasis suppressor by targeting MMP11 and PBX3 in colorectal cancer

Accumulating evidence shows that microRNAs, functioning as either oncogenes or tumour suppressors by negatively regulating downstream target genes that are actively involved in tumour initiation and progression, may be promising biomarkers and therapy targets. Data mining through a microRNA chip database indicated that let-7c may be associated with tumour metastasis. Here, we confirmed that down-regulation of let-7c in primary cancer tissues was significantly associated with metastases, advanced TNM stages and poor survival of colorectal cancer patients. Moreover, ectopic expression of let-7c in a highly metastatic Lovo cell line remarkably suppressed cell migration and invasion in vitro by the down-regulation of K-RAS, MMP11 and PBX3, as well as tumour growth and metastases in vivo, whereas inhibition of let-7c in low-metastatic HT29 cells increased cell motility and invasion by the enhanced gene expression of K-RAS, MMP11 and PBX3. Interestingly, the luciferase reporters' activities with the 3'-UTRs of K-RAS, MMP11 and PBX3 were inhibited significantly by let-7c. Importantly, rescue experiments involving the over-expression of these genes without their 3'-UTRs completely reversed the effects of let-7c on tumour metastasis, both in vitro and in vivo. Finally, the levels of let-7c were inversely correlated with those of MMP11 and PBX3, but not with those of K-RAS. Taken together, these results demonstrate that let-7c, apart from its tumour growth suppression role, also functions as a tumour metastasis suppressor in colorectal cancer by directly destabilizing the mRNAs of MMP11 and PBX3 at least.

Matrix metalloproteinase-11 overexpressed in lobular carcinoma cells of the breast promotes anoikis resistance

The purpose of the present study was to examine the pathobiological properties of a matrix metalloproteinase, MMP-11 (also known as stromelysin-3), in the carcinogenesis of lobular carcinoma of the breast. Immunohistochemical staining demonstrated immunoreactivity with specific antibody to MMP-11 in 16 of 30 lobular carcinoma cells, but not in the non-cancerous terminal duct lobular unit. In positive cases, both noninvasive and invasive cancer cells exhibited immunoreactivity with anti-MMP-11 antibody; however, the staining patterns in noninvasive and invasive foci were distinct. In the noninvasive foci, immunoreactivity was observed in the cytoplasm beneath the plasma membrane, whereas immunoreactivity was found in all of the cytoplasm of infiltrating lobular carcinoma cells. Enforced expression of MMP-11 in the cultured lobular carcinoma MDA-MB-330 cells did not affect cell growth or Matrigel invasion activity. By contrast, overexpression of MMP-11 significantly increased resistance to anoikis, a programmed cell death triggered by a lack of proper cell matrix interaction, as evidenced by decrease in annexin V-positive cells and apoptotic DNA ladders. The present findings indicate that MMP-11 is overexpressed in many lobular carcinoma cells and that it may play a role in lobular carcinogenesis through increasing resistance to anoikis.

Deficiency in trefoil factor 1 (TFF1) increases tumorigenicity of human breast cancer cells and mammary tumor development in TFF1-knockout mice

Although trefoil factor 1 (TFF1; previously named pS2) is abnormally expressed in about 50% of human breast tumors, its physiopathological role in this disease has been poorly studied. Moreover, controversial data have been reported. TFF1 function in the mammary gland therefore needs to be clarified. In this study, using retroviral vectors, we performed TFF1 gain- or loss-of-function experiments in four human mammary epithelial cell lines: normal immortalized TFF1-negative MCF10A, malignant TFF1-negative MDA-MB-231 and malignant TFF1-positive MCF7 and ZR75.1. The expression of TFF1 stimulated the migration and invasion in the four cell lines. Forced TFF1 expression in MCF10A, MDA-MB-231 and MCF7 cells did not modify anchorage-dependent or -independent cell proliferation. By contrast, TFF1 knockdown in MCF7 enhanced soft-agar colony formation. This increased oncogenic potential of MCF7 cells in the absence of TFF1 was confirmed in vivo in nude mice. Moreover, chemically induced tumorigenesis in TFF1-deficient (TFF1-KO) mice led to higher tumor incidence in the mammary gland and larger tumor size compared with wild-type mice. Similarly, tumor development was increased in the TFF1-KO ovary and lung. Collectively, our results clearly show that TFF1 does not exhibit oncogenic properties, but rather reduces tumor development. This beneficial function of TFF1 is in agreement with many clinical studies reporting a better outcome for patients with TFF1-positive breast primary tumors.

Pro-cathepsin D interacts with the extracellular domain of the beta chain of LRP1 and promotes LRP1-dependent fibroblast outgrowth

Interactions between cancer cells and fibroblasts are crucial in cancer progression. We have previously shown that the aspartic protease cathepsin D (cath-D), a marker of poor prognosis in breast cancer that is overexpressed and highly secreted by breast cancer cells, triggers mouse embryonic fibroblast outgrowth via a paracrine loop. Here, we show the requirement of secreted cath-D for human mammary fibroblast outgrowth using a three-dimensional co-culture assay with breast cancer cells that do or do not secrete pro-cath-D. Interestingly, proteolytically-inactive pro-cath-D remains mitogenic, indicating a mechanism involving protein-protein interaction. We identify the low-density lipoprotein (LDL) receptor-related protein-1, LRP1, as a novel binding partner for pro-cath-D in fibroblasts. Pro-cath-D binds to residues 349-394 of the β chain of LRP1, and is the first ligand of the extracellular domain of LRP1β to be identified. We show that pro-cath-D interacts with LRP1β in cellulo. Interaction occurs at the cell surface, and overexpressed LRP1β directs pro-cath-D to the lipid rafts. Our results reveal that the ability of secreted pro-cath-D to promote human mammary fibroblast outgrowth depends on LRP1 expression, suggesting that pro-cath-D-LRP1β interaction plays a functional role in the outgrowth of fibroblasts. Overall, our findings strongly suggest that pro-cath-D secreted by epithelial cancer cells promotes fibroblast outgrowth in a paracrine LRP1-dependent manner in the breast tumor microenvironment.

Matrix metalloproteinase 11/stromelysin-3 exerts both activator and repressor functions during the hematogenous metastatic process in mice

MMP11 expression is a poor prognosis factor in human carcinomas. Although it has been shown to favor primary tumor development, its role in metastatic processes remains unclear. We studied the hematogenous metastatic activity of C26 mouse colon cancer cells injected into the tail vain of wild-type or MMP11-deficient mice during 2 months. Using X-ray computed tomography to image metastasis development in recipient living mice, lung metastases were found to occur earlier and to grow faster in wild-type mice. Histological analyses of the lung, liver, kidney, adrenal gland, mammary gland, ovary and salivary gland, performed at the end of experiment, also showed lower numbers of metastases in wild-type mice, regardless of organ. Lung metastases showed similar Factor VIII-positive vascular networks regardless of the mouse MMP11 status. However, those found in MMP11-deficient mice also exhibited vessel-like structures that did not express Factor VIII, Lyve-1 and vimentin, and were not stained with PAS. Consequently, they did not correspond to vascular or lymphatic vessels or to vascular mimicry channels. Collectively, these results revealed significant spatio-temporal variability that is dependent on host MMP11 status. Furthermore, they point-out the paradoxical role of MMP11 in favoring the onset and growth of lung metastases but limiting lung foci number, and inhibiting the cancer cell dissemination to other organs. These data highlight the complexity of the metastatic process in which the same factor can play activator or repressor functions depending on the metastatic step.

Matrix metalloproteinase-induced epithelial-mesenchymal transition in breast cancer

Matrix metalloproteinases (MMPs) degrade and modify the extracellular matrix (ECM) as well as cell-ECM and cell-cell contacts, facilitating detachment of epithelial cells from the surrounding tissue. MMPs play key functions in embryonic development and mammary gland branching morphogenesis, but they are also upregulated in breast cancer, where they stimulate tumorigenesis, cancer cell invasion and metastasis. MMPs have been investigated as potential targets for cancer therapy, but clinical trials using broad-spectrum MMP inhibitors yielded disappointing results, due in part to lack of specificity toward individual MMPs and specific stages of tumor development. Epithelial-mesenchymal transition (EMT) is a developmental process in which epithelial cells take on the characteristics of invasive mesenchymal cells, and activation of EMT has been implicated in tumor progression. Recent findings have implicated MMPs as promoters and mediators of developmental and pathogenic EMT processes in the breast. In this review, we will summarize recent studies showing how MMPs activate EMT in mammary gland development and in breast cancer, and how MMPs mediate breast cancer cell motility, invasion, and EMT-driven breast cancer progression. We also suggest approaches to inhibit these MMP-mediated malignant processes for therapeutic benefit.

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

Matrix metalloproteinases (MMPs) are a superfamily of Zn(2+)-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.

Role of carcinoma-associated fibroblasts and hypoxia in tumor progression

In recent years, a variety of experimental evidence has convincingly shown that progression of malignant tumors does not depend exclusively on cell-autonomous properties of the cancer cells, but can also be influenced by the tumor stroma. The concept that cancer cells are subjected to microenvironmental control has thus emerged as an important chapter in cancer biology. Recent findings have suggested an important role, in particular, for macrophages, endothelial cells, and cancer-associated fibroblasts (CAFs) in tumor growth and progression. Numerous lines of evidence indicate that the bone marrow is the source, at least in part, of these cells. This chapter summarizes our current knowledge of how bone marrow contributes to the tumor stroma, with particular emphasis on CAFs. The potential role of hypoxia in modulating the differentiation and activity of CAFs, and the therapeutical implications of targeting CAFs for anticancer therapy are discussed.

The clinical implications of MMP-11 and CK-20 expression in human breast cancer

BACKGROUND

Tumor invasiveness and metastasis in cancer progression is manifested by epigenetic abnormality. However, it remains unknown whether transcription regulation of matrix metalloproteinase-11(MMP-11) and cytoskeleton-20 (CK-20) genes for the homoeostasis of epithelial/connective interface that can enhance cell dissemination and invasion may act as alternative mutators to tumor clinicopathology.

METHODS

Paired cancerous and tumor-adjacent normal tissues from 72 breast cancer patients were assayed for the expression of MMP-11 and CK-20 by using real-time RT-PCR. The expression profiles were evaluated for the association with clinicopathological factors.

RESULTS

Breast tumor tissues displayed higher expression levels of MMP-11 and CK-20 than those of the adjacent non-cancerous tissues. Overexpression of either MMP-11 or CK-20 correlated with patients having poorly differentiated tumors (P(MMP-11)=0.01 and P(CK-20)=0.05) and lymph node metastasis (LNM) (P(MMP-11)=0.004 and P(CK-20)=0.001). A synergistic effect between MMP-11 and CK-20 on risk elevation was significant in patients with advanced tumor stage (OR=2.03, 95%CI=1.10-3.77) and LNM (OR=2.83, 95%CI=1.20-4.71). Additionally, patients lacking progesterone receptor exhibited high expression of MMP-11 and CK-20.

CONCLUSION

We demonstrate that MMP-11 and CK-20 are probable prognostic markers whose expression reflects the stages of tumor differentiation and LNM of breast cancer.

MMP11: a novel target antigen for cancer immunotherapy

PURPOSE

Matrix metalloproteinases (MMP) are zinc-dependent endopeptidases that mediate numerous physiologic and pathologic processes, including matrix degradation, tissue remodeling, inflammation, and tumor metastasis. To develop a vaccine targeting stromal antigens expressed by cancer-associated fibroblasts, we focused on MMP11 (or stromelysin 3). MMP11 expression correlates with aggressive profile and invasiveness of different types of carcinoma.

EXPERIMENTAL DESIGN

To show the efficacy of a vaccine targeting MMP11, we constructed a series of plasmid DNA vectors expressing murine MMP11. Mice were vaccinated by i.m. injection followed by in vivo DNA electroporation. A chemically induced, MMP11-overexpressing colon cancer model was established and characterized. Antibody and T-cell responses were determined, and immunoreactive epitopes were characterized. To analyze the possible use of MMP11 as tumor-associated antigen in cancer patients, HLA-A2.1 transgenic mice (HHD) were used to identify reactive epitopes as tools to assess immunogenicity in humans.

RESULTS

Using microarray, we confirmed the overexpression of MMP11 mRNA in a large panel of human tumor samples. MMP11 vaccine induced cell mediated and antibody immune response and exerted significant antitumoral protection in mice with colon cancer in prophylactic and therapeutic settings. HHD transgenic mice were vaccinated with a plasmid encoding human MMP11, and a HLA-A2.1--restricted epitope (hMMP(237)) was identified. hMMP(237) was shown to be immunogenic in human peripheral blood mononuclear cells (PBMC) by in vitro priming.

CONCLUSION

Our study describes the identification of MMP11 as a novel broadly expressed tumor associated antigen as target candidate for cancer immunotherapy.

Delineating protease functions during cancer development

Much progress has been made in understanding how matrix remodeling proteases, including metalloproteinases, serine proteases, and cysteine cathepsins, functionally contribute to cancer development. In addition to modulating extracellular matrix metabolism, proteases provide a significant protumor advantage to developing neoplasms through their ability to modulate bioavailability of growth and proangiogenic factors, regulation of bioactive chemokines and cytokines, and processing of cell-cell and cell-matrix adhesion molecules. Although some proteases directly regulate these events, it is now evident that some proteases indirectly contribute to cancer development by regulating posttranslational activation of latent zymogens that then directly impart regulatory information. Thus, many proteases act in a cascade-like manner and exert their functionality as part of a proteolytic pathway rather than simply functioning individually. Delineating the cascade of enzymatic activities contributing to overall proteolysis during carcinogenesis may identify rate-limiting steps or pathways that can be targeted with anti-cancer therapeutics. This chapter highlights recent insights into the complexity of roles played by pericellular and intracellular proteases by examining mechanistic studies as well as the roles of individual protease gene functions in various organ-specific mouse models of cancer development, with an emphasis on intersecting proteolytic activities that amplify programming of tissues to foster neoplastic development.

Differential regulation of cell type-specific apoptosis by stromelysin-3: a potential mechanism via the cleavage of the laminin receptor during tail resorption in Xenopus laevis

Matrix metalloproteinases (MMPs) have been extensively studied because of their functional attributes in development and diseases. However, relatively few in vivo functional studies have been reported on the roles of MMPs in postembryonic organ development. Amphibian metamorphosis is a unique model for studying MMP function during vertebrate development because of its dependence on thyroid hormone (T3) and the ability to easily manipulate this process with exogenous T3. The MMP stromelysin-3 (ST3) is induced by T3, and its expression correlates with cell death during metamorphosis. We have previously shown that ST3 is both necessary and sufficient for larval epithelial cell death in the remodeling intestine. To investigate the roles of ST3 in other organs and especially on different cell types, we have analyzed the effect of transgenic overexpression of ST3 in the tail of premetamorphic tadpoles. We report for the first time that ST3 expression, in the absence of T3, caused significant muscle cell death in the tail of premetamorphic transgenic tadpoles. On the other hand, only relatively low levels of epidermal cell death were induced by precocious ST3 expression in the tail, contrasting what takes place during natural and T3-induced metamorphosis when ST3 expression is high. This cell type-specific apoptotic response to ST3 in the tail suggests distinct mechanisms regulating cell death in different tissues. Furthermore, our analyses of laminin receptor, an in vivo substrate of ST3 in the intestine, suggest that laminin receptor cleavage may be an underlying mechanism for the cell type-specific effects of ST3.

Functional genetic mouse models: promising tools for investigation of the proteolytic internet

Knockout mice are the gold standard to probe for the role of a specific protease within the interacting network of proteases, substrates, and inhibitors. This proteolytic network, or protease web, determines cell signaling and organ homeostasis. Therefore, protease deficiency or inhibition is intrinsically tied to alterations within this network, always leading to new molecular phenotypes, which define susceptibility of an organ to disease. Furthermore, recent hints, mainly from research on matrix metalloproteinases, about the impact of the protease web on inter-organ signaling molecules suggest the existence of a proteolytic internet of communicating local organ- or molecular polymorphism-specific networks, thereby defining homeostasis and disease susceptibility in the whole organism.

ADAMTS-1 metalloproteinase promotes tumor development through the induction of a stromal reaction in vivo

ADAMTS-1 (a disintegrin and metalloproteinase with thrombospondin motifs), the first described member of the ADAMTS family, is differentially expressed in various tumors. However, its exact role in tumor development and progression is still unclear. The aim of this study was to investigate the effects of ADAMTS-1 transfection in a bronchial epithelial tumor cell line (BZR) and its potential to modulate tumor development. ADAMTS-1 overexpression did not affect in vitro cell properties such as (a) proliferation in two-dimensional culture, (b) proliferation in three-dimensional culture, (c) anchorage-independent growth in soft agar, (d) cell migration and invasion in modified Boyden chamber assay, (e) angiogenesis in the aortic ring assay, and (f) cell apoptosis. In contrast, ADAMTS-1 stable transfection in BZR cells accelerated the in vivo tumor growth after s.c. injection into severe combined immunodeficient mice. It also promoted a stromal reaction characterized by myofibroblast infiltration and excessive matrix deposition. These features are, however, not observed in tumors derived from cells overexpressing a catalytically inactive mutant of ADAMTS-1. Conditioned media from ADAMTS-1-overexpressing cells display a potent chemotactic activity toward fibroblasts. ADAMTS-1 overexpression in tumors was associated with increased production of matrix metalloproteinase-13, fibronectin, transforming growth factor beta (TGF-beta), and interleukin-1beta (IL-1beta). Neutralizing antibodies against TGF-beta and IL-1beta blocked the chemotactic effect of medium conditioned by ADAMTS-1-expressing cells on fibroblasts, showing the contribution of these factors in ADAMTS-1-induced stromal reaction. In conclusion, we propose a new paradigm for catalytically active ADAMTS-1 contribution to tumor development, which consists of the recruitment of fibroblasts involved in tumor growth and tumor-associated stroma remodeling.

Cancer cells, adipocytes and matrix metalloproteinase 11: a vicious tumor progression cycle

This brief review focuses on the emerging role of matrix metalloproteinase 11 (MMP-11) in cancer progression. It has recently been shown that MMP-11 is induced in adipose tissue by cancer cells as they invade their surrounding environment. MMP-11 negatively regulates adipogenesis by reducing pre-adipocyte differentiation and reversing mature adipocyte differentiation. Adipocyte dedifferentiation in turn leads to the accumulation of nonmalignant peritumoral fibroblast-like cells, which favor cancer cell survival and tumor progression. This MMP-11-mediated bi-directional cross-talk between invading cancer cells and adjacent adipocytes/pre-adipocytes highlights the central role that MMP-11 plays during tumor desmoplasia and represents a molecular link between obesity and cancer.

Matrix metalloproteinase-11/stromelysin-3 exhibits collagenolytic function against collagen VI under normal and malignant conditions

The substrate of matrix metalloproteinase 11 (MMP11) remains unknown. We have recently shown that MMP11 is a negative regulator of adipogenesis, able to reduce and even to revert mature adipocyte differentiation. Here, we have used mouse 3T3L1 cells and human U87MG and SaOS cells to show that MMP11 cleaves the native alpha3 chain of collagen VI, which is an adipocyte-related extracellular matrix component. It is known that extracellular proteolytic processing of this chain is required for correct collagen VI folding. Interestingly, MMP11-deficient fat tissue is less cohesive and exhibits collagen VI alteration, dramatic adipocyte plasma and basement membrane abnormalities and lipid leakage. MMP11 is thus required for correct collagen VI folding and therefore for fat tissue cohesion and adipocyte function. Both MMP11 and collagen VI favor tumor progression. Similar spatio-temporal overexpression at the adipocyte-cancer cell interface has been reported for the two proteins. MMP11-dependent collagen VI processing might therefore be expected to occur during malignancy. Accordingly, collagen VI no longer delineates adipocytes located at the invasive front of breast carcinomas. In conclusion, the native alpha3 chain of collagen VI constitutes a specific MMP11 substrate. This MMP11 collagenolytic activity is functional in fat tissue ontogenesis as well as during cancer invasive steps.

Progress in matrix metalloproteinase research

Matrix metalloproteinases (MMPs) are now acknowledged as key players in the regulation of both cell-cell and cell-extracellular matrix interactions. They are involved in modifying matrix structure, growth factor availability and the function of cell surface signalling systems, with consequent effects on cellular differentiation, proliferation and apoptosis. They play central roles in morphogenesis, wound healing, tissue repair and remodelling in response to injury and in the progression of diseases such as arthritis, cancer and cardiovascular disease. Because of their wide spectrum of activities and expression sites, the elucidation of their potential as drug targets in disease or as important features of the repair process will be dependent upon careful analysis of their role in different cellular locations and at different disease stages. Novel approaches to the specific regulation of individual MMPs in different contexts are also being developed.

Contrasting expression of membrane metalloproteinases, MT1-MMP and MT3-MMP, suggests distinct functions in skeletal development

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is the most ubiquitous and widely studied of the membrane-type metalloproteinases (MT-MMPs). It was thus surprising to find no published data on chicken MT1-MMP. We report here the characterization of the chicken gene. Its low sequence identity with the MT1-MMP genes of other species, high GC content, and divergent catalytic domain explains the absence of data and our difficulties in characterizing the gene. The absence of structural features in the chicken gene that have been suggested to be critical for the activation of MMP-2 by MT1-MMP; for the effect of MT1-MMP on cell migration and for the recycling of MT1-MMP suggest these features are either not essential or that MT1-MMP does not perform these functions in chickens. Comparison of the expression of chicken MT1-MMP with MT3-MMP and with MMP-2 and MMP-13 has confirmed the previously recognized co-expression of MT1-MMP with MMP-2 and MMP-13 in fibrous and vascular tissues, particularly those surrounding the developing long bones in other species. By contrast, MT3-MMP expression differs markedly from that of MT1-MMP and of both MMP-2 and MMP-13. MT3-MMP is expressed by chondrocytes of the developing articular surface. Similar expression patterns of this group of MT-MMPs and MMPs have been observed in mouse embryos and suggest distinct and specific functions for MT1-MMP and MT3-MMP in skeletal development.