Demonstration in vivo that stromelysin-3 functions through its proteolytic activity

Targeted drug delivery systems for matrix metalloproteinase-responsive anoparticles in tumor cells: A review

Nanodrug delivery systems based on tumor microenvironment responses have shown excellent performance in tumor-targeted therapy, given their unique targeting and drug-release characteristics. Matrix metalloproteinases (MMPs) have been widely explored owing to their high specificity and expression in various tumor microenvironments. The design of an enzyme-sensitive nanodelivery system using MMPs as targeted receptors could markedly improve the performance of drug targeting. The current review focuses on the development and application of MMP-responsive drug carriers, and summarizes the classification of single- and multi-target nanocarriers based on their MMP responsiveness. The potential applications and challenges of this nanodrug delivery system are discussed to provide a reference for designing high-performance nanodrug delivery systems.

The fat and the bad: Mature adipocytes, key actors in tumor progression and resistance

Growing evidence has raised the important roles of adipocytes as an active player in the tumor microenvironment. In many tumors adipocytes are in close contact with cancer cells. They secrete various factors that can mediate local and systemic effects. The adipocyte-cancer cell crosstalk leads to phenotypical and functional changes of both cell types, which can further enhance tumor progression. Moreover, obesity, which is associated with an increase in adipose mass and an alteration of adipose tissue, has been established as a risk factor for cancer incidence and cancer-related mortality. In this review, we summarize the mechanisms of the adipocyte-cancer cell crosstalk in both obese and lean conditions as well as its impact on cancer cell growth, local invasion, metastatic spread and resistance to treatments. Better characterization of cancer-associated adipocytes and the key molecular events in the adipocyte-cancer cell crosstalk will provide insights into tumor biology and suggest efficient therapeutic opportunities.

CXCR6 expression in non-small cell lung carcinoma supports metastatic process via modulating metalloproteinases

Lung cancer (LuCa) is the leading cause of cancer-related deaths worldwide regardless of the gender. High mortality associated with LuCa is due to metastasis, molecular mechanisms of which are yet to be defined. Here, we present evidence that chemokine receptor CXCR6 and its only natural ligand, CXCL16, are significantly expressed by non-small cell lung cancer (NSCLC) and are involved in the pathobiology of LuCa. CXCR6 expression was significantly higher in two subtypes of NSCLC (adenocarcinomas-ACs and squamous cell carcinoma-SCCs) as compared to non-neoplastic tissue. Additionally, serum CXCL16 was significantly elevated in LuCa cases as compared to healthy controls. Similar to CXCR6 tissue expression, serum level of CXCL16 in AC patients was significantly higher than SCC patients. Biological significance of this axis was validated using SCC and AC cell lines. Expression of CXCR6 was higher in AC cells, which also showed higher migratory and invasive potential than SCC. Differences in migratory and invasive potential between AC and SCC were due to differential expression of metalloproteinases following CXCL16 stimulation. Hence, our findings suggest clinical and biological significance of CXCR6/CXCL16 axis in LuCa, which could be used as potential prognostic marker and therapeutic target.

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.

Hematopoietic stem cell-derived adipocytes and fibroblasts in the tumor microenvironment

The tumor microenvironment (TME) is complex and constantly evolving. This is due, in part, to the crosstalk between tumor cells and the multiple cell types that comprise the TME, which results in a heterogeneous population of tumor cells and TME cells. This review will focus on two stromal cell types, the cancer-associated adipocyte (CAA) and the cancer-associated fibroblast (CAF). In the clinic, the presence of CAAs and CAFs in the TME translates to poor prognosis in multiple tumor types. CAAs and CAFs have an activated phenotype and produce growth factors, inflammatory factors, cytokines, chemokines, extracellular matrix components, and proteases in an accelerated and aberrant fashion. Through this activated state, CAAs and CAFs remodel the TME, thereby driving all aspects of tumor progression, including tumor growth and survival, chemoresistance, tumor vascularization, tumor invasion, and tumor cell metastasis. Similarities in the tumor-promoting functions of CAAs and CAFs suggest that a multipronged therapeutic approach may be necessary to achieve maximal impact on disease. While CAAs and CAFs are thought to arise from tissues adjacent to the tumor, multiple alternative origins for CAAs and CAFs have recently been identified. Recent studies from our lab and others suggest that the hematopoietic stem cell, through the myeloid lineage, may serve as a progenitor for CAAs and CAFs. We hypothesize that the multiple origins of CAAs and CAFs may contribute to the heterogeneity seen in the TME. Thus, a better understanding of the origin of CAAs and CAFs, how this origin impacts their functions in the TME, and the temporal participation of uniquely originating TME cells may lead to novel or improved anti-tumor therapeutics.

Functional relationship between matrix metalloproteinase-11 and matrix metalloproteinase-14

MMP-11 is a key factor in physiopathological tissue remodeling. As an active form is secreted, its activity must be tightly regulated to avoid detrimental effects. Although TIMP-1 and TIMP-2 reversibly inhibit MMP-11, another more drastic scenario, presumably via hydrolysis, could be hypothesized. In this context, we have investigated the possible implication of MMP-14, since it exhibits a spatiotemporal localization similar to MMP-11. Using native HFL1-produced MMP-11 and HT-1080-produced MMP-14 as well as recombinant proteins, we show that MMP-11 is a MMP-14 substrate. MMP-14 cleaves MMP-11 catalytic domain at the PGG(P1)-I(P1′)LA and V/IQH(P1)-L(P1′)YG scissile bonds, two new cleavage sites. Interestingly, a functional test showed a dramatical reduction in MMP-11 enzymatic activity when incubated with active MMP-14, whereas inactive point-mutated MMP-14 had no effect. This function is conserved between human and mouse. Thus, in addition to the canonical reversible TIMP-dependent inhibitory system, irreversible MMP proteolytic inactivation might occur by cleavage of the catalytic domain in a MMP-dependent manner. Since MMP-14 is produced by HT-1080 cancer cells, whereas MMP-11 is secreted by HFL1 stromal cells, our findings support the emerging importance of tumor-stroma interaction/cross-talk. Moreover, they highlight a Janus-faced MMP-14 function in the MMP cascade, favoring activation of several pro-MMPs, but limiting MMP-11 activity. Finally, both MMPs are active at the cell periphery. Since MMP-14 is present at the cell membrane, whereas MMP-11 is soluble into the cellular microenvironment, this MMP-14 function might represent one critical regulatory mechanism to control the extent of pericellular MMP-11 bioavailability and protect cells from excessive/inappropriate MMP-11 function.

Epithelial-mesenchymal Transition and Cell Invasion

Epithelial-mesenchymal transition (EMT) is a complex process in which epithelial cells acquire the characteristics of invasive mesenchymal cells. EMT has been implicated in cancer progression and metastasis as well as the formation of many tissues and organs during development. Epithelial cells undergoing EMT lose cell-cell adhesion structures and polarity, and rearrange their cytoskeletons. Several oncogenic pathways such as transforming growth factor (TGF) -β, Wnt, and Notch signaling pathways, have been shown to induce EMT. These pathways have activated transcription factors including Snail, Slug, and the ZEB family which work as transcriptional repressors of E-cadherin, thereby making epithelial cells motile and resistant to apoptosis. Mounting evidence shows that EMT is associated with cell invasion and tumor progression.In this review, we summarize the characteristic features of EMT, pathways leading to EMT, and the role of EMT in cell invasion. Three topics are addressed in this review: (1) Definition of EMT, (2) Signaling pathways leading to EMT, (3) Role of EMT in cell invasion. Understanding the role of EMT in cell invasion will provide valuable information for establishing strategies to develop anti-metastatic therapeutics which modulate malignant cellular processes mediated by EMT.

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.

Matrix metalloproteinase induction of Rac1b, a key effector of lung cancer progression

Lung cancer is more deadly than colon, breast, and prostate cancers combined, and treatment improvements have failed to improve prognosis significantly. Here, we identify a critical mediator of lung cancer progression, Rac1b, a tumor-associated protein with cell-transforming properties that are linked to the matrix metalloproteinase (MMP)-induced epithelial-mesenchymal transition (EMT) in lung epithelial cells. We show that expression of mouse Rac1b in lung epithelial cells of transgenic mice stimulated EMT and spontaneous tumor development and that activation of EMT by MMP-induced expression of Rac1b gave rise to lung adenocarcinoma in the transgenic mice through bypassing oncogene-induced senescence. Rac1b is expressed abundantly in stages 1 and 2 of human lung adenocarcinomas and, hence, is an attractive molecular target for the development of new therapies that prevent progression to later-stage lung cancers.

Characterization of Xenopus tissue inhibitor of metalloproteinases-2: a role in regulating matrix metalloproteinase activity during development

BACKGROUND

Frog metamorphosis is totally dependent on thyroid hormone (T3) and mimics the postembryonic period around birth in mammals. It is an excellent model to study the molecular basis of postembryonic development in vertebrate. We and others have shown that many, if not all, matrix metalloproteinases (MMPs), which cleave proteins of the extracellular matrix as well as other substrates, are induced by T3 and important for metamorphosis. MMP activity can be inhibited by tissue inhibitors of metalloproteinase (TIMPs). There are 4 TIMPs in vertebrates and their roles in postembryonic development are poorly studied.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed the TIMP2 genes in Xenopus laevis and the highly related species Xenopus tropicalis and discovered that TIMP2 is a single copy gene in Xenopus tropicalis as in mammals but is duplicated in Xenopus laevis. Furthermore, the TIMP2 locus in Xenopus tropicalis genome is different from that in human, suggesting an evolutionary reorganization of the locus. More importantly, we found that the duplicated TIMP2 genes were similarly regulated in the developing limb, remodeling intestine, resorbing tail during metamorphosis. Unexpectedly, like its MMP target genes, the TIMP2 genes were upregulated by T3 during both natural and T3-induced metamorphosis.

CONCLUSIONS/SIGNIFICANCE

Our results indicate that TIMP2 is highly conserved among vertebrates and that the TIMP2 locus underwent a chromosomal reorganization during evolution. Furthermore, the unexpected upregulation of TIMP2 genes during metamorphosis suggests that proper balance of MMP activity is important for metamorphosis.

The proteolytic activity of MT4-MMP is required for its pro-angiogenic and pro-metastatic promoting effects

Membrane-type 4 matrix metalloprotease (MT4-MMP) expression in breast adenocarcinoma stimulates tumor growth and metastatic spreading to the lung. However, whether these pro-tumorigenic and pro-metastatic effects of MT4-MMP are related to a proteolytic action is not yet known. Through site directed mutagenesis MT4-MMP has been inactivated in cancer cells through Glutamic acid 249 substitution by Alanine in the active site. Active MT4-MMP triggered an angiogenic switch at day 7 after tumor implantation and drastically accelerated subcutaneous tumor growth as well as lung colonization in recombination activating gene-1-deficient mice. All these effects were abrogated upon MT4-MMP inactivation. In sharp contrast to most MMPs being primarily of stromal origin, we provide evidence that tumor-derived MT4-MMP, but not host-derived MT4-MMP contributes to angiogenesis. A genetic approach using MT4-MMP-deficient mice revealed that the status of MT4-MMP produced by host cells did not affect the angiogenic response. Despite of this tumor intrinsic feature, to exert its tumor promoting effect, MT4-MMP requires a permissive microenvironment. Indeed, tumor-derived MT4-MMP failed to circumvent the lack of an host angio-promoting factor such as plasminogen activator inhibitor-1. Overall, our study demonstrates the key contribution of MT4-MMP catalytic activity in the tumor compartment, at the interface with host cells. It identifies MT4-MMP as a key intrinsic tumor cell determinant that contributes to the elaboration of a permissive microenvironment for metastatic dissemination.

Histone deacetylase inhibitors upregulate MMP11 gene expression through Sp1/Smad complexes in human colon adenocarcinoma cells

MMP-11 (stromelysin-3) is a matrix metalloproteinase associated with tumor progression and poor prognosis. Its expression was initially described exclusively in stromal cells surrounding tumors, but more recently it has also been detected in macrophages and hepatocarcinoma cells. Here we show MMP-11 expression in human epithelial colon adenocarcinoma cell lines (Caco-2, HT-29 and BCS-TC2). Treatment of BCS-TC2 cells with butyrate and trichostatin A (TSA) (histone deacetylase inhibitors) increases MMP11 promoter activity and protein expression. Using electrophoretic mobility shift assay (EMSA) and supershift assays, we demonstrate for the first time that Sp1 is able to bind to the GC-boxes within the MMP11 proximal promoter region; this binding has been confirmed by chromatin immunoprecipitation. Sp1 is involved in MMP11 basal expression and it is essential for the upregulation of transcription by histone deacetylase inhibitors as deduced from mutant constructs lacking the Sp1 sites and by inhibition of its binding to the promoter with mithramycin. This regulation requires the formation of Sp1/Smad2 heterocomplexes, which is stimulated by an increase in the acetylation status of Smad after butyrate or TSA treatments. We have also found that ERK1/2-mitogen-activated protein kinase (MAPK), but not p38-MAPK or JNK, is involved in the upregulation of MMP11 by HDAC inhibitors.

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.

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

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

Collagenase-3 expression by tumor cells and gelatinase B expression by stromal fibroblast-like cells are associated with biochemical recurrence after radical prostatectomy in patients with prostate cancer

PURPOSE

To investigate the possible clinical value of the expression of MMPs and their tissue inhibitors (TIMPs) by the different cellular types of the tumor scenario to predict biochemical recurrence in patients undergoing radical prostatectomy due clinically localized prostate cancer.

METHODS

An immunohistochemical study was performed using tissue arrays and specific antibodies against MMPs-1, 2, 7, 9, 11, 13 and 14 and TIMPs-1, 2 and 3 on cancer specimens from 133 patients with clinical localized prostate carcinoma.

RESULTS

Immunostaining for all the proteins studied was localized predominantly in tumor cells, but also in stromal cells in a significant percentage of prostate carcinomas, ranged from 20 to 50% for several proteins in fibroblast-like cells and in mononuclear inflammatory cells. Multivariate analysis according to a Cox model demonstrated that tumor stage (P < 0.0001) and Gleason grading (grades 7-10: 2.08 (1.1-3.9); P < 0.05) were significantly and independently associated with biochemical recurrence. Additionally, the expression of MMP-9 by fibroblast-like cells (P < 0.01) and MMP-13 by tumor cells (P < 0.05) were also variables significantly and independently associated with biochemical recurrence.

CONCLUSIONS

MMP-13 expression by tumor cells and MMP-9 by stromal fibroblast-like cells were independent factors of biochemical recurrence in prostate cancer.

Physiology and pathophysiology of matrix metalloproteases

Matrix metalloproteases (MMPs) comprise a family of enzymes that cleave protein substrates based on a conserved mechanism involving activation of an active site-bound water molecule by a Zn(2+) ion. Although the catalytic domain of MMPs is structurally highly similar, there are many differences with respect to substrate specificity, cellular and tissue localization, membrane binding and regulation that make this a very versatile family of enzymes with a multitude of physiological functions, many of which are still not fully understood. Essentially, all members of the MMP family have been linked to disease development, notably to cancer metastasis, chronic inflammation and the ensuing tissue damage as well as to neurological disorders. This has stimulated a flurry of studies into MMP inhibitors as therapeutic agents, as well as into measuring MMP levels as diagnostic or prognostic markers. As with most protein families, deciphering the function(s) of MMPs is difficult, as they can modify many proteins. Which of these reactions are physiologically or pathophysiologically relevant is often not clear, although studies on knockout animals, human genetic and epigenetic, as well as biochemical studies using natural or synthetic inhibitors have provided insight to a great extent. In this review, we will give an overview of 23 members of the human MMP family and describe functions, linkages to disease and structural and mechanistic features. MMPs can be grouped into soluble (including matrilysins) and membrane-anchored species. We adhere to the 'MMP nomenclature' and provide the reader with reference to the many, often diverse, names for this enzyme family in the introduction.

Comparative study of stromal metalloproteases expression in patients with benign hyperplasia and prostate cancer

PURPOSE

The aim of the present work was to perform a comparative study of stromal cell expressions of MMPs and TIMPs between benign and malignant prostate tissues.

METHODS

An immunohistochemical study was performed using specific antibodies against metalloproteases (MMPs) -1, -2, -7, 9, 11, 13, 14 and their tissue inhibitors (TIMPs) -1, 2 and 3, on prostate specimens from 133 patients with clinical localized prostate carcinoma and from 50 patients with BPH.

RESULTS

Our results showed higher percentages of expressions of MMPs and TIMPs by fibroblasts or by mononuclear inflammatory cells (MICs) in prostate carcinomas compared to these cells in BPH. The detection of MMP-2 expression by stromal fibroblasts and/or MMP-2, 9 and TIMP-3 expression by stromal MICs was associated with a 100% of specificity for diagnoses of prostate cancer. We found that the combination of MMP-2 expression by fibroblasts and/or MMP-9 by MICs and/or TIMP-2 by MICs yielded a sensitivity of 47.4%.

CONCLUSIONS

Despite of a limited sensitivity (50%), the combination of MMP-TIMPs expression in stromal cells (MMP-2 by fibroblasts and TIMPs by MICs) in our study provided a specificity of 100% for prostate cancer diagnosis.

Overexpression of matrix metalloproteinase 11 in human gastric carcinoma and its clinicopathologic significance

Matrix metalloproteinase 11 (stromelysin-3) has recently been reported to play a key role in human tumor progression and poor clinical outcome. The aim of this study was to investigate the significance of matrix metalloproteinase 11 expression in gastric cancer. Using real-time quantitative reverse-transcription polymerase chain reaction analysis and immunohistochemistry, we studied matrix metalloproteinase 11 expression levels in non-malignant gastric tissues and in gastric cancer tissues. The association between matrix metalloproteinase 11 expression levels and tumor stage and grade, as well as metastatic potential, was analyzed. Our results show that matrix metalloproteinase 11 expression was significantly higher in gastric cancer specimens compared with nonmalignant tissues at both transcriptional and protein levels, indicating its positive role in the development of gastric cancer. In addition, increased matrix metalloproteinase 11 expression levels were associated with advanced-stage and high-grade tumors, suggesting its involvement in the progression of gastric cancer. More importantly, increased matrix metalloproteinase 11 expression in gastric cancer specimens was correlated with increased expression of IGF-1, a molecule known to stimulate the proliferation, enhanced survival, and migration of cancer cells. Our results demonstrate that matrix metalloproteinase 11 is a novel factor in the development and progression of gastric cancer and suggest that matrix metalloproteinase 11 is a marker for advanced gastric 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.

Expression of CD147 mediates tumor cells invasion and multidrug resistance in hepatocellular carcinoma

Multidrug resistant (MDR) tumor cells over-expressing P-glycoprotein exhibit variation in invasive behavior. To investigate the mechanisms, we analyzed the expression of CD147. The results showed that CD147 expression was increased in HepG2/Adr cells, as compared to HepG2 cells. The MDR cells produced more MMP11 and MDR1, which promoted HepG2/Adr cells invasion and increased resistance to chemotherapeutic drugs. On the other hand, CD147 silencing in HepG2/Adr cells by RNAi led to the opposite effect. Treatment of tumor cells with U-0126, an inhibitor of MAPK/Erk, also down-regulated MMP11 and MDR1 expression. Thus, CD147 may functionally mediate tumor cells invasion and MDR.

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.

Matrix metalloproteinases stimulate epithelial-mesenchymal transition during tumor development

Matrix metalloproteinases (MMPs) are a family of more than 28 enzymes that were initially identified on the basis of their ability to cleave most elements of the extracellular matrix (ECM) but have subsequently been found to be upregulated in nearly every tumor type. As digestion of the ECM is essential for tumor invasion and metastasis, MMPs have been studied for their role in these later stages of tumor development. More recently, exposure to these enzymes has been found to impact cellular signaling pathways that stimulate cell growth at early stages of tumor progression. MMPs have also been found to cleave intracellular targets and so inducing mitotic abnormalities and genomic instability. Emerging evidence indicates that tumor-associated MMPs can also stimulate processes associated with epithelial-mesenchymal transition (EMT), a developmental process that is activated in tumor cells during cell invasion and metastasis. Investigations of potential therapeutic MMP inhibitors aimed at blocking the protumorigenic tissue alterations induced by MMPs have been complicated by the side effects associated with nonspecific inhibition of normal physiological processes; recent investigations have shown how delineation of the extracellular targets and intracellular signaling pathways by which MMP action on cancer cells can induce EMT provides insight into novel therapeutic targets. Here, we provide an overview of recent findings of MMP action in tumors and the mechanisms by which MMPs induce both phenotypic and genotypic alterations that facilitate tumor progression.

Breast cancer progression: insights into multifaceted matrix metalloproteinases

The restricted view of matrix metalloproteinases (MMPs) as simple destroyers of extracellular matrix components has largely ignored their substantial contribution in many aspects of cancer development and metastatic dissemination. Over the last few years, the relevance of MMPs in the processing of a large array of extracellular and cell surface-associated proteins has grown considerably. Our knowledge about the complex functions of MMPs and how their contribution may differ throughout cancer progression is rapidly expanding. These new findings provide several explanations for the lack of success of MMP inhibition in clinical trials. A complete understanding of MMP biology is needed before considering them, their substrates or their products as therapeutic targets. In this review, we explore the different faces of MMP implication in breast cancer progression by considering both clinical and fundamental aspects.

Regulation of extracellular matrix remodeling and cell fate determination by matrix metalloproteinase stromelysin-3 during thyroid hormone-dependent post-embryonic development

Interactions between cells and extracellular matrix (ECM), in particular the basement membrane (BM), are fundamentally important for the regulation of a wide variety of physiological and pathological processes. Matrix metalloproteinases (MMP) play critical roles in ECM remodeling and/or regulation of cell-ECM interactions because of their ability to cleave protein components of the ECM. Of particular interest among MMP is stromelysin-3 (ST3), which was first isolated from a human breast cancer and also shown to be correlated with apoptosis during development and invasion of tumor cells in mammals. We have been using intestinal remodeling during thyroid hormone (TH)-dependent amphibian metamorphosis as a model to study the role of ST3 during post-embryonic tissue remodeling and organ development in vertebrates. This process involves complete degeneration of the tadpole or larval epithelium through apoptosis and de novo development of the adult epithelium. Here, we will first summarize expression studies by us and others showing a tight spatial and temporal correlation of the expression of ST3 mRNA and protein with larval cell death and adult tissue development. We will then review in vitro and in vivo data supporting a critical role of ST3 in TH-induced larval epithelial cell death and ECM remodeling. We will further discuss the potential mechanisms of ST3 function during metamorphosis and its broader implications.

CD147 depletion down-regulates matrix metalloproteinase-11, vascular endothelial growth factor-A expression and the lymphatic metastasis potential of murine hepatocarcinoma Hca-F cells

Extracellular matrix metalloproteinase inducer (EMMPRIN, CD147), which is a plasma membrane glycoprotein enriched on the surface of many malignant tumors promotes adhesion, invasion and metastasis of tumor cells. In addition, tumor-associated CD147 also induces vascular endothelial growth factors (VEGFs) expression. To investigate the possible role of CD147 in the mouse hepatocarcinoma cell line Hca-F with highly metastatic potential in the lymph nodes, we used an RNA interference (RNAi) approach to silence CD147 expression. The results showed that CD147 depletion in Hca-F cells resulted in the significantly decreased expression of matrix metalloproteinase-11 (MMP-11), VEGF-A at both mRNA and protein levels. The reduced CD147 expression also attenuated the invasive, adhesive, metastatic ability of Hca-F cells to lymph nodes both in vitro and in vivo. Our current findings reveal that the tumor biological marker CD147 functionally mediates MMP-11, VEGF-A expression and tumor lymphatic metastasis.

siRNA targeted against matrix metalloproteinase 11 inhibits the metastatic capability of murine hepatocarcinoma cell Hca-F to lymph nodes

Matrix metalloproteinase-11 (MMP-11) belongs to the particular member of MMP family, a group of zinc-dependent endopeptidases involved in tumor progression, invasion and metastasis. MMP-11 is strongly expressed in tumor cells and stromal fibroblasts located in the immediate vicinity of tumor. This study investigated the possible role of MMP-11 expression in mouse hepatocarcinoma cell line Hca-F with highly lymphatic metastasis potential by RNA interference (RNAi) approach. The results showed that a small interfering RNA (siRNA) targeted against MMP-11 significantly impeded Hca-F cells proliferation and colony formation in soft agar, as well as resulted in Hca-F cell apoptosis. This reduction of MMP-11 expression also led to the decreased migration and adhesion of Hca-F cells dramatically both in vitro and in vivo. Furthermore, in vivo metastasis assay indicated that down-regulation of MMP-11 expression in Hca-F cells attenuated the metastatic potential of Hca-F cells to peripheral lymph nodes. These data together provide compelling evidence into the function of MMP-11 and suggest that MMP-11 act as a tumor lymphatic metastasis-associated gene, and could represent a new potential target for gene therapy.

Stromelysin-3 over-expression enhances tumourigenesis in MCF-7 and MDA-MB-231 breast cancer cell lines: involvement of the IGF-1 signalling pathway

BACKGROUND

Stromelysin-3 (ST-3) is over-expressed in the majority of human carcinomas including breast carcinoma. Due to its known effect in promoting tumour formation, but its impeding effect on metastasis, a dual role of ST-3 in tumour progression, depending on the cellular grade of dedifferentiation, was hypothesized.

METHODS

The present study was designed to investigate the influence of ST-3 in vivo and in vitro on the oestrogen-dependent, non-invasive MCF-7 breast carcinoma cell line as well as on the oestrogen-independent, invasive MDA-MB-231 breast carcinoma cell line. Therefore an orthotopic human xenograft tumour model in nude mice, as well as a 3D matrigel cell culture system, were employed.

RESULTS

Using both in vitro and in vivo techniques, we have demonstrated that over-expression of ST-3 in MCF-7 and MDA-MB-231 cells leads to both increased cell numbers and tumour volumes. This observation was dependent upon the presence of growth factors. In particular, the enhanced proliferative capacity was in MCF-7/ST-3 completely and in MDA-MB-231/ST-3 cells partially dependent on the IGF-1 signalling pathway. Microarray analysis of ST-3 over-expressing cells revealed that in addition to cell proliferation, further biological processes seemed to be affected, such as cell motility and stress response. The MAPK-pathway as well as the Wnt and PI3-kinase pathways, appear to also play a potential role. Furthermore, we have demonstrated that breast cancer cell lines of different differentiation status, as well as the non-tumourigenic cell line MCF-10A, have a comparable capability to induce endogenous ST-3 expression in fibroblasts.

CONCLUSION

These data reveal that ST-3 is capable of enhancing tumourigenesis in highly differentiated "early stage" breast cancer cell lines as well as in further progressed breast cancer cell lines that have already undergone epithelial-mesenchymal transition. We propose that ST-3 induction in tumour fibroblasts leads to the stimulation of the IGF-1R pathway in carcinoma cells, thus enhancing their proliferative capacity. In addition, further different cellular processes seem to be activated by ST-3, possibly accounting for the dual role of ST-3 in tumour progression and metastasis.

Stromelysin-3 is a potent negative regulator of adipogenesis participating to cancer cell-adipocyte interaction/crosstalk at the tumor invasive front

The initial invasive processes during cancer development remain largely unknown. Stromelysin-3/matrix metalloproteinase 11 (ST3/MMP11) is associated with tumor invasion and poor prognosis. We present novel evidence that adipocytes present at human breast tumor invasive front are induced by cancer cells to express ST3. Using mouse syngeneic model, light and electron microscopy showed that in ST3-deficient mice but not in wild-type mice, forced cancer cell-adipocyte interaction/crosstalk results in adipocyte membrane alteration, allowing cancer cell fat infiltration and death. Thus, adipocytes are involved in initial cancer cell survival into connective tissue, and this effect is ST3 mediated. This suggested that ST3 might play a role in adipocyte metabolism. Accordingly, ST3-deficient mice exhibited fat excess and increased mRNA levels of peroxisome proliferator-activated receptor gamma (PPARgamma) and adipocyte protein 2 (aP2) adipogenic markers, indicating that, in vivo, ST3 negatively regulates fat homeostasis. Moreover, ST3-deficient mouse embryonic fibroblasts exhibited a dramatic enhanced potential to differentiate into adipocytes associated with increased PPARgamma and aP2 expression, and recombinant ST3 treatment reverted their differentiation. Thus, in vitro, ST3 reduces adipocyte differentiation in an autocrine manner. High fibroblasts/adipocytes ratio is a stroma feature, and peritumoral fibroblast origin remains debated. Our results support the concept that invading cancer cells aberrantly restore the negative ST3 function on adipogenesis into proximal adipocytes/preadipocytes, leading to the accumulation/maintenance of a particular peritumoral fibroblast subpopulation. Accordingly, in human breast tumors, we observed that ST3-expressing peritumoral fibroblasts are distinct from alpha-smooth muscle actin-expressing myofibroblasts. This constitutes the first report of implication of a MMP in cancer cell-adipocyte interaction/crosstalk during early steps of connective tissue invasion.

Redox properties of tea polyphenols and related biological activities

Plant polyphenolic compounds are known to be strong antioxidants. Because oxidative stress is believed to contribute to many acute and chronic diseases, these polyphenols have been postulated to have many beneficial health effects, such as the prevention of cancer and cardiovascular diseases. Indeed, some of these beneficial effects have been demonstrated in animal models and in some, but not all, epidemiological studies. Nevertheless, only some of these activities have been demonstrated to be associated with the antioxidative activities of polyphenols. In studies with cell lines in culture, some of the observed activities may be due to superoxide and hydrogen peroxide produced during the autooxidation of polyphenols. Such pro-oxidation-dependent reactions may not happen in tissues where the oxygen partial pressure is much lower than that in cell culture medium. This review will use the well-studied tea polyphenol, (-)-epigallocatechin-3-gallate, as an example to illustrate the redox properties of polyphenols and their influence on signaling pathways related to anti-cancer activities. Existing data suggest, however, that most of the relevant mechanisms of cancer prevention by tea polyphenols are not related to their redox properties, but are due to the direct binding of the polyphenol to target molecules, including the inhibition of selected protein kinases, matrix metalloproteinases, and DNA methyltransferases.

From a unique cell to metastasis is a long way to go: clues to stromelysin-3 participation

Stromelysin-3 (ST3) overexpression is associated with poor patient clinical outcome in numerous carcinomas. The ST3 is expressed by peritumoral fibroblast-like cells. Review of the literature shows that ST3 is an active partner of cancer cells along the whole natural cancer history, and is essential for optimal tumor development as it reduces death of cancer cells invading adjacent connective tissues at the primary tumor site. Paradoxically, ST3 lowers metastasis development in vivo in mice. However, this beneficial effect does not counterbalance the deleterious anti-apoptotic function of ST3.

Overexpression of cathepsin F, matrix metalloproteinases 11 and 12 in cervical cancer

BACKGROUND

Cervical carcinoma (CC) is one of the most common cancers among women worldwide and the first cause of death among the Mexican female population. CC progression shows a continuum of neoplastic transitions until invasion. Matrix metalloproteinases (MMPs) and cathepsins play a central role on the enhancement of tumor-induced angiogenesis, cell migration, proliferation, apoptosis and connective tissue degradation. MMPs -2 and -9 expression has been widely studied in cervical cancer. Nevertheless, no other metalloproteinases or cathepsins have been yet related with the progression and/or invasion of this type of cancer.

METHODS

Three HPV18 CC cell lines, two HPV16 CC cell lines and three HPV16 tumor CC tissues were compared with three morphologically normal, HPV negative, cervical specimens by cDNA arrays. Overexpression of selected genes was confirmed by end point semiquantitative reverse transcription-PCR with densitometry. In situ hybridization and protein expression of selected genes was further studied by means of two tissue microarrays, one consisting of 10 HSIL and 15 CC and the other one of 15 normal cervical and 10 LSIL tissues.

RESULTS

TIMP1, Integrins alpha 1 and 4, cadherin 2 and 11, Cathepsins F, B L2, MMP 9, 10 11 and 12 were upregulated and Cathepsin S, L, H and C, Cadherins 3 and 4, TIMP3, MMP 13, Elastase 2 and Integrin beta 8 were found to be downregulated by cDNA arrays. Endpoint RT-PCR with densitometry gave consistent results with the cDNA array findings for all three genes selected for study (CTSF, MMP11 and MMP12). In situ hybridization of all three genes confirmed overexpression in all the HSIL and CC. Two of the selected proteins were detected in LSIL, HSIL and CC by immunohistochemistry.

CONCLUSION

Novel undetected CC promoting genes have been identified. Increased transcription of these genes may result in overexpression of proteins, such as CTSF, MMP11 and MMP12 which could contribute to the pathogenesis of CC.

Prognostic Significance of Stromelysin-3 and Tissue Inhibitor of Matrix Metalloproteinase-2 in Esophageal Cancer

OBJECTIVE

Stromelysins (matrix metalloproteinases: MMP-10 or ST-2 and MMP-11 or ST-3) and tissue inhibitors of matrix metalloproteinases (TIMP-1 and 2) have been shown to be associated with human tumor progression, invasion and metastasis. The aim of the present study was to determine the prognostic significance of these proteins in esophageal squamous cell carcinoma (ESCC).

METHODS

Immunohistochemical analysis was carried out in 65 surgically resected ESCCs and 49 distant histologically normal esophageal tissues and 16 cases of dysplasias. Statistical analyses were performed to determine the associations between the protein expression and clinicopathological parameters and survival of esophageal cancer patients.

RESULTS

Expression of ST-2, ST-3, TIMP-1 and TIMP-2 was observed in 43/65 (66%), 51/65 (78%), 43/65 (66%) and 47/65 (72%) ESCC cases, respectively. Univariate analysis showed that TIMP-2 expression was associated with tumor site (OR = 2.63, p = 0.017). TIMP-1+/TIMP-2+ phenotype was inversely correlated with nodal invasiveness of the tumor (OR = 0.4, p = 0.04). Interestingly, p53 expression was associated with increased levels of ST-3 (OR = 0.11, p = 0.02) and TIMP-1 (OR = 3.2, p = 0.007) suggesting possible involvement of p53 in the regulation of these proteins. An increased expression of ST-2, ST-3, TIMP-1 and TIMP-2 was observed in 11/16 (69%), 7/17 (44%), 11/16 (69%) and 8/16 (50%) dysplasias also suggesting that these alterations are early events in esophageal tumorigenesis. All the ESCC patients were followed up postesophagectomy for a maximum period of 59 months (mean disease-free survival = 12 months). Kaplan-Meier survival analysis showed that patients with ST-3-positive and TIMP-2-negative carcinoma had a significantly shorter disease-free survival (median disease-free survival time of 4 months) as compared to patients in the other groups (median disease-free survival time of 20 months; p = 0.0016). To our knowledge this is the first report showing that ST-3+/TIMP-2- phenotype remained of significant predictive value for disease-free survival (p = 0.0007) in multivariate analysis including a conventional clinicopathological factor, tumor stage (p = 0.051).

CONCLUSION

Our results suggest that ST-3+/TIMP-2- phenotype is an adverse prognosticator in esophageal cancer patients.

Effects of tea polyphenols on signal transduction pathways related to cancer chemoprevention

The inhibition of carcinogenesis by tea and tea polyphenols has been demonstrated in different animal models by many investigators. The mechanisms of this inhibitory activity have also been investigated extensively, mostly in cell culture systems, but no clear conclusion can be reached concerning the cancer preventive mechanisms in vivo. In this article, we reviewed the possible mechanisms, which include the inhibition of specific protein kinase activities, blocking receptor-mediated functions, and inhibition of proteases. These events may lead to cell cycle regulation, growth inhibition, enhanced apoptosis, inhibition of angiogenesis, and inhibition of invasion and metastases. The possible complications of translating results obtained in cell culture studies to animals and humans are discussed. It is likely that multiple signal transduction pathways are involved in the inhibition of carcinogenesis by tea constituents. The relative importance of these pathways needs to be determined in vivo.

Tumor cell-mediated induction of the stromal factor stromelysin-3 requires heterotypic cell contact-dependent activation of specific protein kinase C isoforms

Stromelysin-3 (ST3, MMP-11) has been shown to be strongly overexpressed in stromal fibroblasts of most invasive human carcinomas. However, the molecular mechanisms leading to ST3 expression in nonmalignant fibroblasts remain unknown. The aim of the present study was to analyze the signaling pathways activated in normal pulmonary fibroblasts after their interaction with non-small cell lung cancer (NSCLC) cells and leading to ST3 expression. The use of selective signaling pathway inhibitors showed that conventional and novel protein kinase Cs (PKC) were required for ST3 induction, whereas Src kinases exerted a negative control. We observed by both conventional and real time confocal microscopy that green fluorescent protein-tagged PKCalpha and PKCepsilon, but not PKCdelta, transfected in fibroblasts, accumulate selectively at the cell-cell contacts between fibroblasts and tumor cells. In agreement, RNAi-mediated depletion of PKCalpha and PKCepsilon, but not PKCdelta significantly decreased co-culture-dependent ST3 production. Finally, a tetracycline-inducible expression model allowed us to confirm the central role of these PKC isoforms and the negative regulatory function of c-Src in the control of ST3 expression. Altogether, our data emphasize signaling changes occurring in the tumor microenvironment that may define new stromal targets for therapeutic intervention.

Clinicopathological Significance of Stromelysin-3 Expression in Colorectal Cancer

OBJECTIVE

Stromelysin-3 (ST3) is a member of the matrix metalloproteinases and suggested to play a role in tissue remodeling observed in growth and metastasis of tumors. ST3 overexpression in breast cancer is associated with a worse outcome. Our aims were to analyze ST3 expression in primary colorectal tumors and metastases, and further to identify relationships of the expression to clinicopathological factors.

MATERIALS AND METHODS

ST3 expression was immunohistochemically analyzed in 200 primary colorectal adenocarcinomas and 36 corresponding lymph node metastases.

RESULTS

Scoring was performed by counting the percentages of positive cells and the percentages of positive areas. One hundred and one (51%) cases showed < or = 5% positive cells and 99 (49%) >5% positive cells. One hundred and two (51%) cases showed < or = 30% positive area and 98 (49%) >30% positive area. ST3 expression determined by both scoring methods was individually related to females, distally located tumors, infiltrative growth pattern and microsatellite stability. No relationship was found with age, Dukes' stage, differentiation and survival.

CONCLUSIONS

These results suggest that ST3 protein was more involved in the pathway of colorectal cancer development in females, distal locations, infiltrative growth patterns and microsatellite stability.

Membrane associated proteases and their inhibitors in tumour angiogenesis

Cell surface proteolysis is an important mechanism for generating biologically active proteins that mediate a range of cellular functions and contribute to biological processes such as angiogenesis. Although most studies have focused on the plasminogen system and matrix metalloproteinases (MMPs), recently there has been an increase in the identification of membrane associated proteases, including serine proteases, ADAMs, and membrane-type MMPs (MT-MMPs). Normally, protease activity is tightly controlled by tissue inhibitors of MMPs (TIMPs) and plasminogen activator inhibitors (PAIs). The balance between active proteases and inhibitors is thought to determine the occurrence of proteolysis in vivo. High concentrations of proteolytic system components correlate with poor prognosis in many cancers. Paradoxically, high (not low) PAI-1 or TIMP concentrations predict poor survival in patients with various cancers. Recent observations indicate a much more complex role for protease inhibitors in tumour progression and angiogenesis than initially expected. As knowledge in the field of protease biology has improved, the unforeseen complexities of cell associated enzymes and their interaction with physiological inhibitors have emerged, often revealing unexpected mechanisms of action.

Systematic isolation of genes differentially expressed in normal and cancerous tissue of the pancreas

BACKGROUND

There is increasing knowledge about the genetic basis of pancreatic cancer (PaCa). Tumor suppressor genes (TSGs; e.g. p53 and DPC4) and oncogenes (e.g. K-ras) have been shown to be involved in the development of PaCa. However, the extent of chromosomal changes (gains and losses) implicates that many more genes may be involved in the multistep progression of PaCa. Identification of these genes is essential for understanding the molecular events in the development of PaCa.

METHODS

We assembled public and proprietary libraries of more than 4 million expressed sequence tags using newly developed software tools.

RESULTS

We identified a total of 249 genes with specific expression patterns in normal and cancerous tissue of the pancreas. Of these, 27 genes were found to be preferentially expressed in normal tissue of the pancreas, while 222 genes showed significant upregulation of expression in PaCa. Of the 249 genes, 232 (93.2%) were found to represent known human genes or putative human homologues of genes characterized previously in other species, while 17 (6.8%) represent putative new genes.

CONCLUSION

These genes may represent a valuable source to identify novel TSGs and oncogenes involved in the carcinogenesis of PaCa.

Stromal cell involvement in cancer

Solid tumors co-opt the body's endogenous extracellular proteolytic machinery for their invasion and metastasis. This is supported by a large number of independent observations ranging from histochemical and prognostic studies of cancer patient material to animal experiments. There are several extracellular proteolytic systems that are relevant in the context of cancer, but the plasminogen activation (PA) system and the matrix metalloproteases (MMPs) remain the most thoroughly investigated. Localization studies by immunohistochemistry and in situ mRNA hybridization in tumors of common human cancers have repeatedly identified members of the PA and MMP systems in stromal cells. The cancer cells, of epithelial origin, contribute PA and MMP components in some cases, but their contribution fades in comparison with the overwhelming expression of proteolytic components by fibroblasts, macrophages, endothelial cells, and other stromal cells. Ideal animal models of human cancers should recapitulate this fundamental proteolytic aspect of tumor biology. However, in the transplantable tumor models where PA or MMP components have been studied at the cellular level in vivo, this is most often not the case. Transgenic cancer models may provide a closer parallel to the human situation, in that PA and MMP components are synthesized by the tumor stroma. The pivotal role of stromal cells has been confirmed experimentally in mouse models in which the expression pattern of proteolytic components is strongly reminiscent of human tumors. In these models it is possible to reconstitute the wild-type tumor characteristics of proteolytically deficient tumor-bearing mice by transplantation with wild-type fibroblasts or hemapoietic cells. These studies collectively show that cancer-associated proteolysis is a collaborative effort of malignant cancer cells and various stromal cells--a collaboration in which stromal cells contribute the majority of the active proteolytic components that are necessary for the invasive behavior of the tumors. This cellular division of labor positions the stromal cells as prime targets for future research and possibly therapy. Vascular endothelial cells are already the focus of intense therapeutically relevant research, but tumor-associated fibroblasts, macrophages, neutrophils, lymphendothelial cells, etc. provide additional largely unexplored territory in the ongoing search for efficient countermeasures against invasive cancer.

Active stromelysin-3 (MMP-11) increases MCF-7 survival in three-dimensional Matrigel culture via activation of p42/p44 MAP-kinase

Stromelysin-3 (ST3) has the characteristic structure of matrix metalloproteinases (MMP), but its substrate specificity and pattern of expression differ markedly from that of other MMP family members. ST3 was originally isolated on the basis of its expression in primary breast cancers and has been shown to be overexpressed in virtually all primary carcinomas, suggesting that ST3 participates in the initial development of epithelial malignancies. Recent data using murine models reported that ST3 expression was able to increase tumor take by suppressing cell apoptosis. Our present goal was to set up an in vitro model in which we could study this new function. For this purpose, we analyzed survival of MCF-7 transfectants expressing either wild-type or catalytically inactive ST3 (ST3wt or ST3cat-) in three-dimensional (3-D) culture conditions by inclusion in Matrigel. In such conditions, that mimic the in vivo microenvironment, we found a marked decrease in the percentage of cell death when active ST3 was expressed (ST3wt transfectants vs. ST3cat- or vector only transfectants) as assessed by FACS and TUNEL analysis. The addition of batimastat, a broad spectrum MMP inhibitor, reversed the increased cell survival in ST3wt transfectants, confirming that ST3 enzymatic activity was required for this effect. Finally, we analyzed the expression of anti- and pro-apoptotic proteins as well as activation of cell survival pathways and we found that ST3-mediated cell survival was accompanied by activation of both p42/p44 MAPK and AKT. Our data confirm and extend the anti-apoptotic function of ST3 and provide a useful model to dissect this new role and identify new physiological substrates.

Identification of peptide substrates for human MMP-11 (stromelysin-3) using phage display

The MMP-11 proteinase, also known as stromelysin-3, probably plays an important role in human cancer because MMP-11 is frequently overexpressed in human tumors and MMP-11 levels affect tumorogenesis in mice. Unlike other MMPs, however, human MMP-11 does not cleave extracellular matrix proteins, such as collagen, laminin, fibronectin, and elastin. To help identify physiologic MMP-11 substrates, a phage display library was used to find peptide substrates for MMP-11. One class of peptides containing 26 members had the consensus sequence A(A/Q)(N/A) downward arrow (L/Y)(T/V/M/R)(R/K), where downward arrow denotes the cleavage site. This consensus sequence was similar to that for other MMPs, which also cleave peptides containing Ala in position 3, Ala in position 1, and Leu/Tyr in position 1', but differed from most other MMP substrates in that proline was rarely found in position 3 and Asn was frequently found in position 1. A second class of peptides containing four members had the consensus sequence G(G/A)E downward arrow LR. Although other MMPs also cleave peptides with these residues, other MMPs prefer proline at position 3 in this sequence. In vitro assays with MMP-11 and representative peptides from both classes yielded modest kcat/Km values relative to values found for other MMPs with their preferred peptide substrates. These reactions also showed that peptides with proline in position 3 were poor substrates for MMP-11. A structural basis for the lower kcat/Km values of human MMP-11, relative to other MMPs, and poor cleavage of position 3 proline substrates by MMP-11 is provided. Taken together, these findings explain why MMP-11 does not cleave most other MMP substrates and predict that MMP-11 has unique substrates that may contribute to human cancer.