Dual over-expression pattern of membrane-type metalloproteinase-1 in cancer and stromal cells in human gastrointestinal carcinoma revealed by in situ hybridization and immunoelectron microscopy

A DNA aptamer recognizing MMP14 for in vivo and in vitro imaging identified by cell-SELEX

A key challenge for the management of various types of cancer, including pancreatic cancer and hepatocellular carcinoma, is accurate diagnosis at an early stage. Matrix metalloproteinase 14 (MMP14) is overexpressed in numerous types of cancer and is associated with poor prognosis. Therefore, MMP14-specific imaging probes have potential use in the diagnosis of MMP14-positive cancer. Aptamers are short oligonucleotide sequences that can bind to molecular targets with a high specificity and affinity. Aptamers are typically obtained from an in vitro library; this process is usually termed systematic evolution of ligands by exponential enrichment (SELEX). In the present study, a DNA aptamer targeting MMP14 was obtained by cell-SELEX and termed M17, which specifically recognizes MMP14-positive cells. Aptamer M17 selectively binds to membrane proteins of MMP14-transfected 293T cells (Kd, 4.98±1.26 nM). Pancreatic cancer cell imaging suggested that aptamer M17 can bind to the cell membranes of two pancreatic cancer cell lines (MIA PaCa-2 and PANC-1). In vivo tumor imaging demonstrated that the targeting recognition of MIA PaCa-2 tumor cells in mice could be visualized using Cy5-labeled aptamer M17. Aptamer M17-conjugated polyethylene glycol-Fe3O4 can specifically bind to MIA PaCa-2 and PANC-1 cells, and reduce MRI T2-weighted imaging signal intensity. The DNA aptamer M17 has the advantages of simplicity of synthesis, small size, low immunogenicity, high penetrability and high affinity. Therefore, aptamer M17 is a potential molecular probe for the diagnosis and treatment of MMP14-positive cancer.

miR-181a-5p Inhibits Cancer Cell Migration and Angiogenesis via Downregulation of Matrix Metalloproteinase-14

Upregulation of matrix metalloproteinase MMP-14 (MT1-MMP) is associated with poor prognosis in cancer patients, but it is unclear how MMP-14 becomes elevated in tumors. Here, we show that miR-181a-5p is downregulated in aggressive human breast and colon cancers where its levels correlate inversely with MMP-14 expression. In clinical specimens, enhanced expression of MMP-14 was observed in cancer cells located at the invasive front of tumors where miR-181a-5p was downregulated relative to adjacent normal cells. Bioinformatics analyses defined a potential miR-181a-5p response element within the 3'-untranslated region of MMP-14 that was validated in reporter gene experiments. Ectopic miR-181a-5p reduced MMP-14 expression, whereas miR-181a-5p attenuation elevated MMP-14 expression. In support of a critical relationship between these two genes, miR-181a-5p-mediated reduction of MMP-14 levels was sufficient to decrease cancer cell migration, invasion, and activation of pro-MMP-2. Furthermore, this reduction in MMP-14 levels was sufficient to reduce in vivo invasion and angiogenesis in chick chorioallantoic membrane assays. Taken together, our results establish the regulation of MMP-14 in cancers by miR-181a-5p through a posttranscriptional mechanism, and they further suggest strategies to elevate miR-181a-5p to prevent cancer metastasis.

Biomechanics of TGFβ-induced epithelial-mesenchymal transition: implications for fibrosis and cancer

Fibrosis, a disease that results in loss of organ function, contributes to a significant number of deaths worldwide and sustained fibrotic activation has been suggested to increase the risk of developing cancer in a variety of tissues. Fibrogenesis and tumor progression are regulated in part through the activation and activity of myofibroblasts. Increasing evidence links myofibroblasts found within fibrotic lesions and the tumor microenvironment to a process termed epithelial-mesenchymal transition (EMT), a phenotypic change in which epithelial cells acquire mesenchymal characteristics. EMT can be stimulated by soluble signals, including transforming growth factor (TGF)-β, and recent studies have identified a role for mechanical cues in directing EMT. In this review, we describe the role that EMT plays in fibrogenesis and in the progression of cancer, with particular emphasis placed on biophysical signaling mechanisms that control the EMT program. We further describe specific TGFβ-induced intracellular signaling cascades that are affected by cell- and tissue-level mechanics. Finally, we highlight the implications of mechanical induction of EMT on the development of treatments and targeted intervention strategies for fibrosis and cancer.

Increased immunoreactivity of membrane type-1 matrix metalloproteinase (MT1-MMP) and β-catenin in high-risk basal cell carcinoma

BACKGROUND

Although various immunohistological markers have been investigated to assess the aggressive characteristics of basal cell carcinoma (BCC), the role of membrane type-1 matrix metalloproteinase (MT1-MMP) has not been well established.

OBJECTIVES

To clarify the precise role of MT1-MMP in BCC, MT1-MMP expression was studied in various histological subtypes of BCC.

MATERIALS AND METHODS

High-risk subtypes of BCC were compared by assessing the expression of β-catenin and MT1-MMP. The tissue microarray technique was used for immunohistochemical staining. Fifty-eight samples were divided into six subtypes (10 nodular, 12 mixed, nine infiltrative, eight morphoeiform, 10 micro-nodular and nine basosquamous). Overall, the 10 nodular BCC samples were classified as low-risk BCC and the remaining 48 samples were classified as high-risk BCCs.

RESULTS

β-Catenin immunoreactivity was increased in the high-risk BCCs compared with the low-risk (nodular) BCC (P < 0·001). Nuclear β-catenin immunoreactivity was increased at the invading front of mixed BCC tumour islands compared with the upper portion of the lesion (P < 0·01). For the mixed BCC (P < 0·01), infiltrative BCC (P < 0·001), morphoeiform BCC (P < 0·001), micronodular BCC (P < 0·001) and basosquamous (P < 0·001) carcinoma, β-catenin immunoreactivity was increased at the invading front compared with nodular BCC. MT1-MMP immunoreactivity was increased in the high-risk BCCs compared with the low-risk (nodular) BCC (P < 0·01). The membranous MT1-MMP immunoreactivity was increased at the invading front of mixed BCC tumour islands compared with the upper portion of the lesions (P < 0·01). For the mixed (P < 0·01), infiltrative (P < 0·05), morphoeiform (P < 0·05), micronodular (P > 0·05) and basosquamous (P < 0·05) BCC, MT1-MMP immunoreactivity was also increased at the invading front compared with nodular BCC.

CONCLUSIONS

The results of this study suggest that MT1-MMP might be a novel marker for high-risk BCC. In addition, expression of both β-catenin and MT1-MMP was increased in high-risk BCC tumour cells, indicating that these two proteins may play an important role in locally invasive and highly destructive growth behaviour of high-risk BCCs.

Differential expression patterns of MMPs and their role in the invasion of epithelial premalignant tumors and invasive cutaneous squamous cell carcinoma

Co-expression of several members of the matrix metalloproteinase (MMP) family is characteristic of human malignant tumors. MMP-2, MMP-9, TIMP-2, and MT1-MMP are thought to be involved in the process of destruction of basement membranes and stromal invasion by neoplastic epithelial cells. In this study, we investigated the expression and role of MMPs in cutaneous oncogenesis. Tissue microarray consisting of 62 squamous cell carcinomas (SCC), 32 Bowen's disease (BD) samples, 25 normal epidermis samples were obtained for the study. MMP-2,-9, MT1-MMP and TIMP-2 proteins were examined by immunohistochemical staining and mRNA level was detected by quantitative RT-PCR in fresh tissues consisting of 5 cutaneous SCCs and paired normal epidermis samples. Gelatinase activity of MMP-2 and MMP-9 was investigated by gelatin zymography and protein levels of MT1-MMP and TIMP-2 were measured by western blot in 2 human SCC cell lines. The invasive property was evaluated with invasion assays using Transwell filters. SCC exhibited significantly increased MMP-2, MT1-MMP and decreased TIMP-2 mRNA and protein expression compared to that of the normal epithelium. Immunohistochemical staining revealed that MT1-MMP was strongly expressed on the invasive front of SCCs, whereas BD exhibited higher expression around the dyskeratotic cells in the epithelium. In comparison with the expression observed in BD, SCC exhibited significantly increased MMP-2 expression. In addition, high MMP-2 and MT1-MMP expression and low TIMP-2 expression had a significant positive correlation with the invasiveness of SCC cell lines in vitro. Our results revealed significantly increased MT1-MMP and MMP-2 expression and decreased TIMP-2 expression in cutaneous SCC, and the expression correlated with the invasiveness of SCC cell lines. Therefore, the expression of these factors in cutaneous tumors may serve as an indicator of tumor aggressiveness and invasion.

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.

Arsenic enhances matrix metalloproteinase-14 expression in fibroblasts

This study focused on the effects of arsenic (As) on fibroblast-derived matrix metalloproteinase (MMP)-2 and -14 levels, as these proteins were reported to be associated with tumor progression. Arsenic was found to promote production of the fibroblast-derived active form of MMP-2. Further, As at 100 or 1000 microM increased MMP-14 expression levels in fibroblasts. In addition, 1000 microM mercury (Hg) but not As increased pro-MMP-2 protein, which is involved in the conversion of the proenzyme into its active form. Since MMP-14 is an activator of pro-MMP-2, data suggest that As promotes production of fibroblast-derived active form of MMP-2 through increased expression of MMP-14. Evidence indicates that As appeared to be less effective than Hg in the conversion of pro-MMP-2 into its active form.

Modifying the soil to affect the seed: role of stromal-derived matrix metalloproteinases in cancer progression

In the 1980's, as the importance of matrix metalloproteinases (MMPs) in cancer progression was discovered, it was recognized that in most tumors these proteases were abundantly and sometimes exclusively expressed not by tumor cells, but by normal host-derived cells like fibroblasts, vascular endothelial cells, myofibroblasts, pericytes or inflammatory cells that contribute to the tumor microenvironment. Later experiments in mice deficient in specific MMPs revealed that host-derived MMPs play a critical role not only in tumor cell invasion, but also in carcinogenesis, angiogenesis, vasculogenesis and metastasis. Tumor cells secrete many factors, cytokines and chemokines that directly or indirectly increase the expression of these MMPs in the tumor microenvironment where they exert extracellular matrix (ECM) degrading and sheddase activities. The knowledge of the complex role that stromal-derived MMPs play in the interaction between tumor cells and stromal cells should allow us to consider specific windows in cancer treatment when MMP inhibition could have a valuable therapeutic effect.

Up-regulation of matrix metalloproteinase-2 and membrane-type 1-matrix metalloproteinase were coupled with that of type I procollagen in granulation tissue response after the onset of aortic dissection

The pathophysiological significance of matrix metalloproteinases (MMPs) in aortic dissection remains poorly understood. The purpose of the present study is to clarify the significance of MMPs in aortic dissection. The activities and distributions of MMP-2, membrane-type 1-MMP (MT1-MMP), and MMP-9 were evaluated by gelatin zymography, immunohistochemistry, and in situ hybridization in 29 patients and seven autopsy cases. To assess if these MMPs are related to a tissue remodeling process, we compared the expression of these MMPs with that of type I procollagen and platelet-derived growth factor receptor beta chain (PDGF Rbeta). Patients were divided into three groups based on histological findings: acute, intermediate, and healed groups. The most remarkable changes were observed in the intermediate group, in which MMP-2 activity peaked and tissue expression of mRNAs for MMP-2 and MT1-MMP were observed in spindle-shaped cells in the neointima, organizing thrombus, and the adventitia. These expression patterns were essentially coupled with those of type I procollagen mRNA and PDGF-Rbeta protein. The association of MMP-2, MT1-MMP, type I procollagen, and PDGF-Rbeta suggests that MMP-2 and MT1-MMP could be involved not only in the degradation of aortic tissue but also in tissue remodeling, which may be associated with the healing process.

Accumulation of CCR5+ T cells around RANTES+ granulomas in Crohn's disease: a pivotal site of Th1-shifted immune response?

Immunological abnormalities are implicated in the pathogenesis of inflammatory bowel disease (IBD), that is, Crohn's disease and ulcerative colitis. In particular, Crohn's disease is considered to be a T helper type 1 (Th1)-shifted disease. Chemokines and their receptors are involved in various immune responses including Th1- and Th2 responses. In this study, we analyzed chemokines and their receptors by immunohistochemistry, using frozen sections derived from 33 patients with Crohn's disease and 24 with ulcerative colitis. In inflamed mucosa, small mononuclear cells predominantly expressed CCR5 and CXCR3, the receptors selectively expressed on Th1 cells, without significant differences between Crohn's disease and ulcerative colitis. We then focused on the noncaseating granulomas that are characteristic of Crohn's disease. Granuloma cells, observed in all the layers of intestinal tissues, were positive for RANTES/CCL5 protein along their cell membranes. Lymphocytes surrounding granulomas were mostly CCR5+ and CXCR3+ T cells with CD4+ and CD8+ cells at similar frequencies. Granuloma cells were positive for RANTES mRNA by in situ hybridization. By contrast, lymphoid aggregates in Crohn's disease and lymphoid follicles in the normal intestinal mucosa were characterized by abundant B cells, a predominance of CD4+ T cells over CD8+ T cells, and low frequencies of cells expressing CCR5 or CXCR3. Together with the notion that granuloma cells are possible antigen-presenting cells, our results suggest that the noncaseating granulomas could be one of the crucial sites of Th1-shifted immune responses in Crohn's disease.

Infiltration of CD8+ T cells containing RANTES/CCL5+ cytoplasmic granules in actively inflammatory lesions of human chronic gastritis

Chronic gastritis is frequently associated with infection of Helicobacter pylori and characterized by tissue infiltration of neutrophils, lymphocytes, and plasma cells. To address the mechanism of lymphocyte infiltration in chronic gastritis, we examined the expression of chemokines and their receptors using frozen sections of chronic gastritis, obtained from 23 patients who underwent gastrectomy for gastric cancer. By immunohistochemistry, lymphocytes in inflamed gastric mucosa expressed CCR5 abundantly, CXCR3 less frequently, and CCR4 sparsely. The numbers of CCR5(+) cells, which were composed of mainly CD8(+) and partly CD4(+) T cells, were positively correlated with the degree of neutrophil infiltration, and decreased in areas with intestinal metaplasia or mucosal atrophy. RANTES/CCL5, one of the ligands of CCR5, was localized mainly in CD8(+) and partly CD4(+) T cells with a characteristic dotted pattern, and such lymphocytes were most densely distributed around the neck region of gastric glands. In situ hybridization confirmed the expression of CCL5 mRNA in these cells, and immunoelectron microscopy revealed localization of CCL5 in the membrane-bound granules, which most probably corresponded to the cytolytic granules of cytotoxic T cells. The numbers of CCL5(+) lymphocytes showed a close correlation with the degree of neutrophil infiltration and markedly decreased in intestinal metaplasia. In conclusion, our data suggest that, together with neutrophils, CCL5(+) T cells, presumably activated cytotoxic T cells, would play important roles in the active inflammatory process of chronic gastritis. Our data also suggest a self-recruiting mechanism involving CCR5 and CCL5 for tissue accumulation of such T cells.

Membrane-type 1 matrix metalloproteinase: a key enzyme for tumor invasion

Matrix metalloproteinases (MMPs) are believed to play a pivotal role in malignant behavior of cancer cells such as rapid tumor growth, invasion, and metastasis by degrading extracellular matrix (ECM). Different types of synthetic inhibitors against MMPs (MMPIs) were developed as candidates for anti-cancer therapeutics and so far clinical trials had led to no significant success. However, this does not diminish the importance of MMPs in the malignancy of cells. Details about MMPs, specifically when and how they take part in the development of cancer are necessary for more advanced application of MMPIs. In this paper, we summarize recent knowledge about membrane-type 1 matrix metalloproteinase (MT1-MMP) which is expressed on cancer cell surface as an invasion-promoting proteinase. By localizing at the leading edge of invasive cancer cells, MT1-MMP degrades components of the tissue barriers. One of the major targets is type I collagen, the most abundant ECM component. Although MT1-MMP itself cannot degrade type IV collagen in the basement membrane, it binds to and activates proMMP-2, one of the type IV collagenases. However, degradation of the ECM is not the sole function of MT1-MMP. MT1-MMP also regulates cell-ECM interaction by processing cell adhesion molecules such as CD44 and integrin alphav chain, and eventually promotes cell migration as well. In addition to the transcriptional regulation, invasion-promoting activity of the MT1-MMP is also strictly monitored at the post-translational level. Precise knowledge about the regulation will give us insight to develop new methods for treating invasive cancer patients.

Matrix metalloproteinases in tumor progression: focus on basal and squamous cell skin cancer

Many normal biological processes, such as reproduction, fetal development and wound healing, are critically dependent on controlled degradation of extracellular matrix (ECM) macromolecules. However, excessive degradation of matrix components occurs in pathologic tissue destruction, e.g. in atherosclerosis, rheumatoid arthritis, and cancer. Matrix metalloproteinases (MMPs) are degradative enzymes that play an important role in all aspects of tumor progression by enhancing tumor-induced angiogenesis and destroying local tissue architecture and basement membranes to allow tumor invasion and metastasis. Efficient breakdown of the ECM surrounding invasive cancer islands involves interplay between tumor cells, stromal cells, and inflammatory cells, all of which express a distinct set of MMPs. Besides the classical role of MMPs in degradation of ECM, MMPs may also indirectly influence the tumor microenvironment through the release of growth factors, cryptic sites or angiogenic factors, or through the generation of matrix fragments that inhibit tumor cell proliferation, migration and angiogenesis. This makes the contribution of MMPs to tumorigenesis much more complex than initially thought. Currently, a number of clinical studies have focused on testing MMP inhibitors as potential antineoplastic agents. In this review we discuss the present role of MMPs in the development and progression of cancer, focusing on non-melanoma skin cancers basal (BCC) and squamous (SCC) cell carcinoma, and the possible influence of MMPs in their differences.

Expression of membrane type I-matrix metalloproteinase in oral squamous cell carcinoma

A local invasion and lymph node metastasis (LNM) of an oral squamous cell carcinoma (OSCC) has a poor prognosis, and involves the degradation of the extracellular matrix mediated by multiple proteolytic enzymes including membrane type I-matrix metalloproteinase (MT1-MMP). This study aimed to determine the role of MT1-MMP in OSCC, to evaluate the immunohistochemical expression of MT1-MMP with regard to the invasiveness and LNM of the OSCC, and to evaluate the major source of MT1-MMP mRNA and its protein using immunohistochemistry and in situ hybridization. MT1-MMP expression was examined in 46 OSCCs via immunohistochemistry and non-radioisotope in situ hybridization. The relationship between MT1-MMP expression and LNM, as well as the histological invasiveness, was statistically analyzed. The results showed that whereas 12 out of the 18 OSCCs (66.7%) with LNM showed moderate to strong MT1-MMP expression, only nine of the 28 OSCCs (32.1%) without LNM expressed MT1-MMP strongly. MT1-MMP expression was significantly higher with regard to LNM (P=0.022). As the invasion grade became stronger (from grade a to grade d), MT1-MMP was significantly more strongly expressed (P=0.033). These results suggest that MT1-MMP is primarily secreted in the OSCC cells and is involved in the invasiveness of the OSCC and LNM. Moreover, MT1-MMP combined with other markers may be used to predict the metastatic potential of an OSCC.

MT1-MMP expression promotes tumor growth and angiogenesis through an up-regulation of vascular endothelial growth factor expression

Membrane type 1 metalloprotease (MT1-MMP) is a transmembrane metalloprotease that plays a major role in the extracellular matrix remodeling, directly by degrading several of its components and indirectly by activating pro-MMP2. We investigated the effects of MT1-MMP overexpression on in vitro and in vivo properties of human breast adenocarcinoma MCF7 cells, which do not express MT1-MMP or MMP-2. MT1-MMP and MMP-2 cDNAs were either transfected alone or cotransfected. All clones overexpressing MT1-MMP 1) were able to activate endogenous or exogenous pro-MMP-2, 2) displayed an enhanced in vitro invasiveness through matrigel-coated filters independent of MMP-2 transfection, 3) induced the rapid development of highly vascularized tumors when injected subcutaneously in nude mice, and 4) promoted blood vessels sprouting in the rat aortic ring assay. These effects were observed in all clones overexpressing MT1-MMP regardless of MMP-2 expression levels, suggesting that the production of MMP-2 by tumor cells themselves does not play a critical role in these events. The angiogenic phenotype of MT1-MMP-producing cells was associated with an up-regulation of VEGF expression. These results emphasize the importance of MT1-MMP during tumor angiogenesis and open new opportunities for the development of anti-angiogenic strategies combining inhibitors of MT1-MMP and VEGF antagonists.

Close association between Fas ligand (FasL; CD95L)-positive tumor-associated macrophages and apoptotic cancer cells along invasive margin of colorectal carcinoma: a proposal on tumor-host interactions

Anti-tumor immune responses are considered to be one of the key host reactions in human colorectal cancer, with T cells as important effector cells. For the induction of tumor-specific immunity, processing of cancer cells and priming of T cells by antigen-presenting cells are important. The present study was designed to clarify the relationship between Fas ligand (FasL; CD95L) expression and apoptotic cancer cells. Immunohistochemistry using frozen sections taken from 58 patients with colorectal cancer revealed that stromal cells composed mainly of tumor-associated macrophages expressed FasL, leaving cancer cells negative for FasL. These macrophages were abundantly distributed along the invasive margin. In situ hybridization revealed that these macrophages as well as cancer cells expressed FasL mRNA, whereas macrophages in the normal colon mucosa rarely expressed FasL. Apoptotic cancer cells recognized by monoclonal antibody M30 CytoDEATH were localized not only in cancer cell nests, but also in the stroma along the invasive margin showing a dissociated pattern, which was particularly evident in the areas of FasL+ macrophages. Furthermore, these macrophages, phenotypically similar to dendritic cells, occasionally contained M30+ apoptotic cancer cells in the cytoplasm. Clinicopathologic analyses in 123 cases revealed 1) a positive correlation between the degree of dissociated M30+ apoptotic cancer cells and the number of macrophages along the invasive margin and 2) an inverse association between the degree of dissociated M30+ apoptotic cancer cells and the occurrence of hematogenous metastasis after surgical resection of the primary tumor. In conclusion, the present study shows the importance of FasL+ activated macrophages as one of the host defense mechanisms against cancer cell spread in human colorectal cancer.

Matrix metalloproteinases in colorectal cancer

Matrix metalloproteinases (MMPs) appear to play a key role in the development and progression of human malignancies. MMPs mediate the destruction of the extracellular matrix, which is an important early step in tumor invasion and metastasis. Growing evidence suggests that MMPs also have angiogenic activity and participate in the early stages of tumorigenesis and primary tumor growth. Investigations in experimental animal models have confirmed the importance of MMPs in the pathogenesis of colorectal cancer, and studies in humans show a direct association between increased MMP expression and tumor invasiveness, development of metastases, and shortened survival. In this review, the physiologic role of MMPs in normal tissues is examined and data supporting the role of MMPs in the pathogenesis of colorectal cancer are reviewed. The results of clinical trials with MMP inhibitors in colorectal cancer and promising areas for future investigation are also discussed.

Activated matrix metalloproteinase-2--a potential marker of prognosis for epithelial ovarian cancer

OBJECTIVES AND METHODS

To investigate the relationship between the expression of matrix metalloproteinase-2 (MMP-2) and clinical characteristics in patients with epithelial ovarian tumors, we examined the expression of MMP-2 in 26 epithelial benign ovarian tumors (EBOT) and 41 epithelial ovarian carcinomas (EOC) using semi-quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry. We also analyzed pro-MMP-2 and activated MMP-2 in epithelial ovarian tumors using Western blot. RESULTS The expression levels of MMP-2 mRNA and overall protein were higher in EOC than in EBOT, but the differences were not statistically significant (P > 0.05). MMP-2 mRNA and immunoreactive protein for MMP-2 were not significantly associated with clinicopathological features in EOC. The positive percentages of the active form of MMP-2 were 71% in EOC and 42% in EBOT, respectively (P < 0.05). The positive percentage of the active form of MMP-2 in stage III and IV EOC was significantly higher (81%) than that (33%) in stage I and II EOC (P = 0.01). The expression of activated MMP-2 was significantly related to disease progression in EOC (P = 0.02). The percentages of active MMP-2 in positive immunoreaction tumor cells and fibroblasts were, respectively, 96 and 89%. The difference was not statistically significant (P = 0.54). The positive and negative predictive values of active MMP-2 for disease progression were 65 (19/29) and 75% (9/12), respectively, and the accuracy was 68% (28/41).

CONCLUSION

MMP-2 generally appears in epithelial ovarian tumors and there is a tendency to express more MMP-2, and especially activated MMP-2, in EOC. MMP-2 mRNA and pro-MMP-2 are not associated with the clinicopathological features in patients with EOC. There was a significant relationship between activated MMP-2 and invasiveness, metastasis, and disease progression in EOC and activated MMP-2 is a potential marker of prognosis.

Platelet-derived growth factor and its receptors are expressed in areas of both active inflammation and active fibrosis in inflammatory bowel disease

The aim of the present study is to clarify in situ expression of platelet-derived growth factor (PDGF) and its receptors in different phases of inflammatory bowel disease (IBD). Tissues samples were obtained from 20 patients with ulcerative colitis (UC) and 29 with Crohn's disease (CD) at surgery. In situ hybridization and immunohistochemistry on frozen sections were performed for PDGF-A and -B and its alpha and beta receptors (alphaR and betaR). The area of active inflammation was infiltrated by abundant polymorphonuclear and mononuclear leukocytes, of which the latter expressed mRNA and proteins of PDGF-A, -B, and -alphaR and mRNA for PDGF-betaR. The area of active fibrosis, characterized by activated fibroblasts/ myofibroblasts, was juxtaposed to ulceration, which is induced as a repair process to tissue destruction. In these areas, activated fibroblasts/myofibroblasts were positive for mRNA and protein of PDGF-A, -B, -alphaR, and -betaR. The expression of PDGF-A, -B, and -alphaR declined significantly in the scar area. Our results suggest that PDGF is not only important as an inducer of fibrosis in the repair phase but also it is involved in the active inflammatory phase possibly as a chemoattractant for mononuclear inflammatory cells.

Membrane-type 1 matrix metalloproteinase enhances lymph node metastasis of gastric cancer

The mechanisms of the lymph node metastasis remain unclear. We demonstrate the role of MT1-MMP on the lymph node metastasis using in vivo experimental model of lymph node metastasis by orthotopic implantation of MT1-MMP transfected gastric cancer cell line in the stomach of nude rats. TMK-1 cell line without expression of MT1-MMP was transfected with the pcDNA3 plasmid containing a 3.4-kb MT1-MMP cDNA fragment by calcium phosphate method, and the transfected cell line was designated as TMK-MT. Western blot and RT-PCR analyses showed the specific bands corresponding to MT1-MMP in the TMK-MT cells. By gelatin zymography, the activated form (62-kDa) of MMP-2 was identified in the medium of TMK-MT cell line, but was not detected in TMK-1 cells. Six weeks after orthotopic implantation of TMK-1 and TMK-MT xenografts of nude mouse-subcutaneus tumor into the stomach of nude rats, gastric tumors were found in all the animals. Histologically, the lymphatic invasion was found in the submucosa of the TMK-MT gastric tumors. Lymph node metastasis was not detected in nude rats bearing TMK-1 gastric tumor (0/8). In contrast, lymph node metastasis was detected in five out of 8 rats, bearing TMK-MT gastric tumor. MT1-MMP immunoreactivity was found on the cell membrane and cytoplasm of TMK-MT cells not only in the lymph node metastasis but also in the stomach tumor. These results suggest that MT1-MMP overexpression induced by transfection of its gene may promote lymph node metastasis of transformed cells.

Vascular smooth muscle cells and pericytes express MMP-1, MMP-9, TIMP-1 and type I procollagen in inflammatory bowel disease

AIMS

Matrix metalloproteinases (MMPs) are involved in tissue remodelling, which is one of the important aspects of inflammatory disease. To assess the balance between the matrix degradation and production, we analysed the in situ expression of MMP-1, -3, -8 and -9, tissue inhibitor of metalloproteinases (TIMP)-1 and -2, and type I procollagen (PC-I) in inflammatory bowel disease.

METHODS AND RESULTS

Immunohistochemistry using frozen sections was performed in 17 patients with ulcerative colitis (UC) and 16 with Crohn's disease (CD). In both UC and CD, MMPs and TIMPs were expressed by inflammatory cells as well as by fibroblastic cells most prominently in actively inflamed areas in ulcer bases, but sparsely in intact inflamed mucosa in both UC and CD. In UC, inflamed mucosa with erosions expressed these substances focally. Fibroblasts also expressed PC-I. We identified that vascular smooth muscle cells of venules in ulcer bases expressed MMP-1 and -9, TIMP-1 and PC-I. These venules also expressed E-selectin, a cell adhesion molecule to facilitate the leucocyte extravasation, and vascular endothelial growth factor (VEGF) receptor 2, consistent with their property of newly formed vessels.

CONCLUSIONS

Our results suggest that MMPs are involved in the tissue remodelling, angiogenesis and promotion of leucocyte extravasation in the actively inflamed area in the ulcer base in both UC and CD. MMP-1 expression in the mucosa may be related to the initial step of ulceration in UC. Therapeutic manipulation of extracellular matrix turnover would be an effective therapy to alleviate active inflammation and accelerate ulcer healing.

Expression of membrane-type 1, 2, and 3 matrix metalloproteinases messenger RNA in ovarian carcinoma cells in serous effusions

We studied the levels of matrix metalloproteinase (MMP)-2, membrane-type (MT)1-MMP, MT2-MMP, and MT3-MMP in 43 malignant pleural and peritoneal effusions using reverse transcription-polymerase chain reaction (RT-PCR) and cellular localization of MT1-MMP in 66 effusion specimens and 85 corresponding primary and metastatic tumors using messenger RNA (mRNA) in situ hybridization (ISH). In 43 effusions, MMP-2 mRNA was detected in 37, MT1-MMP in 25, and MT2-MMP in 32. Expression of MT1-MMP and MT2-MMP was found in 21 specimens; in 16 MT-MMP-positive specimens, mRNA for only 1 of 2 enzymes was expressed. MT3-MMP mRNA was not detected. High levels of MMP-2 mRNA were detected more often in effusions with high MT1-MMP and/or MT2-MMP mRNA expression. Using ISH, MT1-MMP mRNA was localized to cancer cells in 27 of 58 malignant effusions; focal signals were detected in mesothelial cells in 7 of 42. MT1-MMP was localized to tumor cells in 32 of 85 primary and metastatic solid lesions, and stromal cells expressed MT1-MMP in 3. Tumor cell MT1-MMP expression in effusion specimens did not differ from primary or metastatic lesions. MT-MMP expression in tumor cells in effusions showed no association with effusion site or tumor type using ISH and RT-PCR.

Clinicopathological significance of tumor nest configuration in patients with esophageal squamous cell carcinoma

BACKGROUND

Cancer-stromal interactions are an important mediator of cancer invasion and metastasis.

METHODS

The authors investigated the clinicopathological significance of tumor nest configuration and the surrounding stroma in 159 patients with advanced esophageal squamous cell carcinoma (ESCC). The tumors were classified microscopically into two types. Type A tumors had oval-shaped or sheet-like tumor nests (with > 80% of the tumor area showing these features). Type B tumors had asteroid-shaped or scattered small tumor nests (with > 20% of the tumor area showing these features).

RESULTS

Of the 159 tumors examined, 38 (24%) were type A and 121 (76%) were type B. Type B tumors had a significantly deeper invasion depth, more frequent lymphatic permeation and lymph node metastasis, more prominent active fibroblastic stroma, and less frequent inflammatory cell infiltration (P < 0.05). Both univariate (P < 0.05) and multivariate (P < 0.05) analysis of the patients' survival showed that the prognosis for patients with type B tumors was significantly worse than for patients with type A tumors.

CONCLUSIONS

This study showed that tumor nest configuration, which corresponded to the behavior of tumor cells against stromal cells, correlated well with the aggressiveness of the tumor.

Differential patterns of stromelysin-2 (MMP-10) and MT1-MMP (MMP-14) expression in epithelial skin cancers

Co-expression of several members of the matrix metalloproteinase (MMP) family is characteristic of human malignant tumours. To investigate the role of stromelysin-2 (MMP-10) in growth and invasion of skin tumours, we studied cutaneous carcinomas with high metastatic capacity (squamous cell carcinomas, SCCs), only locally destructive tumours (basal cell carcinomas, BCCs) and pre-malignant lesions (Bowen's disease and actinic keratosis) using in situ hybridization. Expression of MMP-10 was compared with that of stromelysin-1 (MMP-3) and of MT1-MMP, the expression of which has been shown to correlate with tumour invasiveness. MMP-10 was expressed in 13/21 SSCs and 11/19 BCCs only in epithelial laminin-5 positive cancer cells, while premalignant lesions were entirely negative. MT1-MMP mRNA was detected in 19/21 SCCs both in epithelial cancer cells and stromal fibroblasts and in 14/18 BCCs only in fibroblasts. The level of MMP-10 was upregulated in a cutaneous SCC cell line (UT-SCC-7) by transforming growth factor-alpha and keratinocyte growth factor, and by interferon-gamma in combination with transforming growth factor-beta1 and tumour necrosis factor-alpha both in UT-SCC-7 and HaCaT cells. Our results show that MMP-10 expression does not correlate with the invasive behaviour of tumours as assessed by their histology and MT1-MMP expression, but may be induced by the wound healing and inflammatory matrix remodelling events associated with skin tumours.

Expression of heparanase in normal, dysplastic, and neoplastic human colonic mucosa and stroma. Evidence for its role in colonic tumorigenesis

The human heparanase gene, an endo-beta-glucuronidase that cleaves heparan sulfate at specific intrachain sites, has recently been cloned and shown to function in tumor progression and metastatic spread. Antisense digoxigenin-labeled heparanase RNA probe and monoclonal anti-human heparanase antibodies were used to examine the expression of the heparanase gene and protein in normal, dysplastic, and neoplastic human colonic mucosa. To our knowledge, this is the first systematic study of heparanase expression in human colon cancer. Both the heparanase gene and protein were expressed at early stages of neoplasia, already at the stage of adenoma, but were practically not detected in the adjacent normal-looking colon epithelium. Gradually increasing expression of heparanase was evident as the cells progressed from severe dysplasia through well-differentiated to poorly differentiated colon carcinoma. Deeply invading colon carcinoma cells showed the highest levels of the heparanase mRNA and protein associated with expression of both the gene and enzyme by adjacent desmoplastic stromal fibroblasts. A high expression was also found in colon carcinoma metastases to lung, liver, and lymph nodes, as well as in the accompanying stromal fibroblasts. Moreover, extracts derived from tumor tissue expressed much higher levels of the heparanase protein and activity as compared to the normal colon tissue. In all specimens, the heparanase gene and protein exhibited the same pattern of expression. These results suggest a role of heparanase in colon cancer progression and may have both prognostic and therapeutic applications.

Matrix metalloproteinases, their tissue inhibitors and colorectal cancer staging

BACKGROUND

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are important in tumour invasion and metastasis. The levels of MMPs, TIMPs and total MMP activity were compared in paired colorectal tumour (n = 50) and normal tissue (n = 49) samples and correlated with clinical and pathological staging.

METHODS

Gelatin zymography (MMP-2 and MMP-9), enzyme-linked immunosorbent assays (MMP-1, MMP-3, TIMP-1 and TIMP-2) and quenched fluorescent substrate hydrolysis (total MMP activity) were employed in resection specimens from 50 patients, four with adenomas and 46 with colorectal cancer.

RESULTS

The levels of active MMP-2 and MMP-9 and total MMP-1, MMP-3 and TIMP-1 were significantly greater in tumour tissue than in normal colon (e.g. TIMP-1 tumour median 72 (range 25-351) versus normal 26 (4-107) ng per mg total protein content; P<0.05); however, TIMP-2 levels were significantly greater in normal tissue (P<0.05). Total MMP activity was significantly greater in tumour than in normal tissue (15 025 (1750-174 400) versus 7250 (750-354 650) pmol l-1 min-1 mg protein-1; P<0.05). Correlations were found between both MMP and TIMP levels and pathological tumour staging. MMP-1 appeared to be most important as its concentration correlated positively with Dukes staging, tumour differentiation and lymphatic invasion.

CONCLUSION

The levels of the studied MMPs and total MMP activity were upregulated in colorectal tumours. MMP-1 is important in colorectal cancer progression.

Expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) on prostate cancer cell lines

Membrane-type metalloproteinase-1 (MT1-MMP) is a transmembrane metalloproteinase, which activates proMMP-2 and expressed on the cell surface in many invasive cancer cells. We investigated the expression of MT1-MMP in prostate cancer cell lines. MT1-MMP protein and mRNA were expressed in PC-3, DU-145 and TSU-pr1 cells (androgen-independent prostate cancer cell lines), but in LNCaP cells (androgen-dependent prostate cancer cell line). MT1-MMP protein was negative and mRNA was low to detect by RT-PCR. Cell lysate of PC-3 cleaved proMMP-2 to the active form. In addition, both hepatocyte growth factor (HGF) and gastrin-releasing peptide (GRP) increased Matrigel invasion and induced the expression of MT1-MMP protein in DU-145 prostate cancer cells. These results suggest that MT1-MMP is indeed the tumor-specific activator of proMMP-2 in androgen-independent prostate cancer cells and plays an important role in the invasive properties of prostate cancer cells.

Macrophage-derived MT1-MMP and increased MMP-2 activity are associated with glomerular damage in crescentic glomerulonephritis

Membrane-type matrix metalloproteinases (MT-MMPs) have been shown to activate pro-MMP-2 on the cell surface and are suggested to be key enzymes in tissue remodelling under various physiological and pathological conditions. To investigate the role of MT-MMP in progressive renal injury, the gene expression and enzymatic activity of MT-MMP were examined in crescentic glomerulonephritis induced by anti-glomerular basement membrane (GBM) antibody in WKY rats. Isolated glomeruli were subjected to RNA and protein extraction 0, 1, 3, 7, 14, and 28 days after intravenous injection of rabbit anti-GBM antibody. Semiquantitative RT-PCR analysis revealed that among the three members of the MT-MMP family, mRNA expression of MT2-MMP remained unchanged and that of MT3-MMP was not observed in glomeruli during the development of nephritis. However, MT1-MMP gene expression increased from day 3 and reached maximum levels at day 7 (5.5+/-0.7-fold increase over day 0), closely associated with macrophage accumulation, crescent formation, and increased proteinuria. Gelatin zymography showed that the active from of MMP-2 emerged from day 7 and remained during the experimental period accompanied by increased proMMP-2, while no active form of MMP-2 was found in control rats. Using an antisense cRNA probe, intense signals of MT1-MMP mRNA were observed mostly in cells within the crescent and in some cells in the mesangial areas. Most of these cells were ED-1-positive macrophages, based on immunostaining of sequential sections. These results suggested that in the MT-MMP family, MT1-MMP was induced in infiltrating macrophages during the development of crescentic glomerulonephritis and possibly contributed to pathological degradation of glomerular extracellular matrices through the activation of proMMP-2.

Secreted and membrane-associated matrix metalloproteinases of IL-2-activated NK cells and their inhibitors

We have previously documented that rat IL-2-activated NK (A-NK) cells produce matrix metalloproteinase-2 (MMP-2) and MMP-9. In this study, we describe mouse A-NK cell-derived MMPs, including MT-MMPs, and also TIMPs. RT-PCR analysis from cDNA of mouse A-NK cells revealed mRNA for MMP-2, MMP-9, MMP-11, MMP-13, MT1-MMP, MT2-MMP, TIMP-1, and TIMP-2. MMP-2 and MMP-9 expression was confirmed by gelatin zymography. Moreover, we report for the first time that MT-MMPs are expressed by NK cells, i.e., large granular lymphocytes as determined by both RT-PCR and Western blots. TIMP-1 expression was detected as a 29-kDa protein in Western blots. It is intriguing that TIMP-2 protein from A-NK cells was also detected as a 29-kDa protein, which is clearly different from the previously reported molecular mass of 21 kDa in mouse and human cells. In addition, inhibition of MMPs by BB-94, a selective inhibitor of MMP, significantly inhibited the ability of mouse A-NK cells to migrate through Matrigel, a model basement membrane. Taken together, these findings suggest that A-NK cells may therefore use multiple MMPs in various cellular functions, including degradation of various extracellular matrix molecules as they extravasate from blood vessels and accumulate within cancer metastases following their adoptive transfer.

Membrane-type 1 matrix metalloproteinase mRNA expression in colorectal cancer

PURPOSE

Membrane-type matrix metalloproteinases are recently described proteolytic enzymes belonging to the matrix metalloproteinase family. Initial studies have indicated that membrane-type matrix metalloproteinases are involved in tumor invasion and metastasis. Membrane-type 1 matrix metalloproteinase is the first membrane-type matrix metalloproteinase to be described. The aim of this study was to investigate the expression of membrane-type 1 matrix metalloproteinase mRNA in colorectal cancer.

METHODS

Samples were collected from surgical specimens of patients with colorectal adenocarcinoma and were immediately frozen in liquid nitrogen and stored at -80 degrees C until processed. Both normal and cancer tissue was taken from each patient. TNM stage, tumor differentiation, mucin production, and vascular invasion were assessed. Northern blotting was used to quantify membrane-type 1 matrix metalloproteinase mRNA levels in the samples using a membrane-type 1 matrix metalloproteinase cDNA clone. X-ray film images were digitized and densitometry was used to quantify bands. All samples were normalized against 18S rRNA levels. Results are expressed as the ratio of cancer to normal tissue levels. Statistical analysis was performed using analysis of variance, with P < 0.05 accepted as the level of significance.

RESULTS

A total of 32 samples were prospectively analyzed. The correlation between TNM stage and increased expression of membrane-type 1 matrix metalloproteinase mRNA in cancer tissue over normal tissue is expressed in the mean ratio of cancer to normal tissue expression for Stages I through IV, respectively: 1.4 +/- 0.2 (12 patients); 4.1 +/- 2.6 (8 patients); 3.4 +/- 3 (7 patients); and 4.5 +/- 5 (5 patients). Stage I is significantly different from Stages II and IV (P < 0.05). These preliminary results show an overall increasing trend in membrane-type 1 matrix metalloproteinase expression with increasing tumor stage. However, there was no correlation between membrane-type 1 matrix metalloproteinase expression and mucin production, degree of tumor differentiation, or vascular invasion.

CONCLUSION

Preliminary results indicate that membrane-type 1 matrix metalloproteinase levels correlate with increasing tumor stage.

Unraveling the role of proteases in cancer

Investigators have been studying the expression and activity of proteases in the final steps of tumor progression, invasion and metastasis, for the past 30 years. Recent studies, however, indicate that proteases are involved earlier in progression, e.g., in tumor growth both at the primary and metastatic sites. Extracellular proteases may co-operatively influence matrix degradation and tumor cell invasion through proteolytic cascades, with individual proteases having distinct roles in tumor growth, invasion, migration and angiogenesis. In this review, we use cathepsin B as an example to examine the involvement of proteases in tumor progression and metastasis. We discuss the effect of interactions among tumor cells, stromal cells, and the extracellular matrix on the regulation of protease expression. Further elucidation of the role of proteases in cancer will allow us to design more effective inhibitors and novel protease-based drugs for clinical use.

MMP-2 and TIMP-2 expression correlates with poor prognosis in cervical carcinoma--a clinicopathologic study using immunohistochemistry and mRNA in situ hybridization

OBJECTIVE

The spread of malignant neoplasms is closely associated with matrix and basement membrane degradation, mediated by various classes of proteolytic enzymes. Matrix metalloproteinases (MMP) appear to have a key role in the sequence of events that lead to local invasion and metastasis. The present study evaluated the role of matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinases-2 (TIMP-2), and membrane-type metalloproteinase (MT1-MMP) in cervical neoplasia.

METHODS

We have analyzed 49 uterine cervical squamous cell carcinomas, 10 cases of high-grade cervical intraepithelial neoplasia (CIN II-III), and 10 control cervices for the presence of MMP-2, TIMP-2, and MT1-MMP using in situ hybridization. MMP-2 protein expression was evaluated using immunohistochemistry. Results were analyzed for possible correlation with disease outcome.

RESULTS

MMP-2, TIMP-2, and MT1-MMP mRNA were localized to both stromal and tumor cells. However, an intense signal for MMP-2 was detected almost exclusively in tumor cells and was uniformly absent from CIN lesions and control cervices. Conversely, intense signals for TIMP-2 and MT1-MMP were detected in both stromal and tumor cells of invasive carcinomas, more often for the former. As with MMP-2, they were absent from CIN lesions. MMP-2 protein expression was enhanced in tumor cells compared to CIN cases and controls, significantly compared to the latter (P = 0.01). The presence of both MMP-2 and TIMP-2 mRNA in tumor cells correlated with advanced stage (P = 0.003 for MMP-2, P = 0.002 for TIMP-2) and with poor survival (P = 0.003 for MMP-2, P = 0.002 for TIMP-2) in univariate analysis. In addition, their presence in tumor cells intercorrelated (P = 0.002). In multivariate survival analysis, MMP-2 presence retained its association with survival (P = 0.004), in addition to patient age (P = 0.027) and advanced stage (P = 0. 0002).

CONCLUSIONS

Both MMP-2 and TIMP-2 have a key role in extracellular matrix invasion in cervical carcinoma, largely through their elaboration by tumor cells. The presence of mRNA for both proteins is interrelated and is associated with poor survival.

Retinoic acid synergizes with cyclic AMP to enhance MMP-2 basal promoter activity

Matrix metalloproteinase-2 (MMP-2) degrades basement membrane collagen and its abnormal expression is associated with the enhanced malignancy of metastasizing cancer cells. Retinoids and cyclic AMP analogs have been shown to affect MMP-2 production. Here we demonstrate that the expression of the human MMP-2 gene is enhanced by a synergistic action of retinoic acid (RA) and dibutyryl cyclic AMP (Bt2cAMP). RA also synergizes with Bt2cAMP in enhancing the basal promoter activity when the MMP-2 proximal promoter activity is induced by transient transfection and RA/Bt2cAMP treatment in human fibrosarcoma HT1080 cells. Deletions beyond -315 bp from the transcription initiation site drastically reduce the synergistic enhancement. A search for a cis-element in the MMP-2 proximal promoter shows the presence of a CRE-like sequence (TGACGTCCC) at position -292 bp in the opposite strand. The CRE-like sequence makes complexes with two DNA binding proteins. The results demonstrate that the RA/Bt2cAMP-enhanced transcription of the MMP-2 gene is dependent on the general transcription machinery and suggest that the basal promoter may be a potential target for gene-specific activators.

Evidence for tumor-host cooperation in regulating MMP-2 expression in human colon cancer

Matrix metalloproteinase 2 (MMP-2) facilitates tumor growth and metastasis in colon cancer. Although tumor cells may produce MMP-2, stromal cells, such as macrophages and fibroblasts, contribute significantly to MMP-2 synthesis in human tumors. We characterized four human colon cancer cell lines with differing biological behavior for MMP-2 expression. While the parent tumors from which the cell lines were derived all expressed MMP-2 mRNA, MMP-2 transcripts were detected in only one cell line, TF-17C, which is nontumorigenic in a nude mouse tumor model. TF-43C, which is tumorigenic and metastatic in the same tumor model, did not produce MMP-2, yet the tumors which arose from it after injection into nude mice did contain MMP-2 mRNA, suggesting a contribution from stromal cells. Co-culturing TF-43C with fibroblasts resulted in an increase in MMP-2 protein, whereas co-culturing with the nontumorigenic cell line TF-13Cm did not alter constitutive fibroblast MMP-2 secretion. Conditioned medium from TF-43C cells also stimulated fibroblast MMP-2 production. These data suggest that a soluble factor from TF-43C cells can stimulate fibroblast MMP-2 production and support the hypothesis that colon cancer cell interactions with stromal fibroblasts may be important determinants of tumor behavior in vivo.

Significance of membrane type 1 matrix metalloproteinase expression in breast cancer

Expression of matrix metalloproteinases (MMPs) plays an essential role in tumor metastasis and invasion through the degradation of extracellular matrix (ECM). MT1-MMP (membrane type 1 matrix metalloproteinase), a membrane-type MMP, is responsible for the activation of MMP2. In this study the significance of MT1-MMP expression in human breast tumors was investigated by immunocytochemical assay, and its correlation with clinicobiological features was analyzed. MT1-MMP expression was detected in tumor cells and/or stromal cells, and there was a strong correlation between the expressions of MT1-MMP in the two cell types. Out of 183 primary tumors, 103 (56.2%) showed positive staining of MT1-MMP in tumor cells. MT1-MMP expression showed no significant correlation with any of the clinicobiological parameters examined, including hormone receptor status and angiogenesis. In postoperative survival analysis, MT1-MMP expression itself was not a significant prognostic factor. However, in the particular subgroup with the accumulation of thymidine phosphorylase (TP)-positive stromal cells, which have been activated by various stimuli, such as cytokines and hypoxia, MT1-MMP expression had a significant prognostic value. These data suggested that MT1-MMP might function cooperatively with tumor-associated stromal cells for the progression of breast cancer.

MMP-2 release and activation in ovarian carcinoma: the role of fibroblasts

The matrix metalloproteinase MMP-2 is up-regulated in epithelial cancers and its mRNA localizes to stromal fibroblasts. In this paper we show that co-culture of ovarian carcinoma cells with fibroblasts resulted in an enhanced release of proMMP-2 and TIMP-2 into the culture medium. Cell-cell interaction was a major factor in this response and carcinoma cells stimulated proMMP-2 release from fibroblasts but not vice versa. Collagen 1, in a dose-dependent fashion, induced activation of proMMP-2 by tumour-derived, but not normal, fibroblasts. Antibody to beta1 integrin also induced proMMP-2 activation by tumour-derived fibroblasts. The activation involved the processing of proMMP-2 by a membrane-bound metalloproteinase. We propose that, in the ovarian tumour microenvironment, interaction between tumour cells and fibroblasts may enhance fibroblast production of the proMMP-2 and TIMP-2. Collagen I, also present in the ovarian tumours, then induces these fibroblasts to activate proMMP-2 even in the presence of TIMP-2. This active MMP-2 can associate with the cell surface of tumour cells and fibroblasts and is used in the processes of tissue remodelling and invasion.

Identification and characterization of the fifth membrane-type matrix metalloproteinase MT5-MMP

A new member of the membrane-type matrix metalloproteinase (MT-MMP) subfamily tentatively named MT5-MMP was isolated from mouse brain cDNA library. It is predicted to contain (i) a candidate signal sequence, (ii) a propeptide region with the highly conserved PRCGVPD sequence, (iii) a potential furin recognition motif RRRRNKR, (iv) a zinc-binding catalytic domain, (v) a hemopexin-like domain, (vi) a 24-residue hydrophobic domain as a potential transmembrane domain, and (vii) a short cytosolic domain. Reverse transcriptase-polymerase chain reaction analysis of its transcripts indicates that MT5-MMP is expressed in a brain-specific manner consistent with the origin of its EST clone from cerebellum. It is also highly expressed during embryonic development at stages day 11 and 15. Like other MT-MMPs, MT5-MMP specifically activates progelatinase A when co-expressed in Madin-Darby canine kidney cells. Its ability to activate progelatinase A is dependent on its proteolytic activity since a mutation converting Glu to Ala in the zinc binding motif HE255LGH renders MT5-MMP inactive against progelatinase A. In contrast to other MT-MMPs, MT5-MMP tends to shed from cell surface as soluble proteinases, thus offering flexibility as both a cell bound and soluble proteinase for extracellular matrix remodeling processes. Taken together, these properties serve to distinguish MT5-MMP as a versatile MT-MMP playing an important role in extracellular matrix remodeling events in the brain and during embryonic development.

Metalloproteinases and tissue inhibitors of metalloproteinases

Because the proteolytic degradation of extracellular matrix is required for invasion and metastasis, it would appear that the important family of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) might be prognostic indicators of the invasive potential of a breast tumor. Nevertheless, there are few data demonstrating an independent prognostic value of any individual MMPs or TIMPs in primary breast cancer patients. It is possible, however, that the balance among levels of certain MMPs and their inhibitors will be more informative, since MMPs are clearly involved in paracrine tumor-stromal interactions and are associated with angiogenesis, which does appear to be prognostic.

Membrane-type 1 matrix metalloprotease (MT1-MMP) enables invasive migration of glioma cells in central nervous system white matter

Invasive glioma cells migrate preferentially along central nervous system (CNS) white matter fiber tracts irrespective of the fact that CNS myelin contains proteins that inhibit cell migration and neurite outgrowth. Previous work has demonstrated that to migrate on a myelin substrate and to overcome its inhibitory effect, rat C6 and human glioblastoma cells require a membrane-bound metalloproteolytic activity (C6-MP) which shares several biochemical and pharmacological characteristics with MT1-MMP. We show now that MT1-MMP is expressed on the surface of rat C6 glioblastoma cells and is coenriched with C6-MP activity. Immunodepletion of C6-MP activity is achieved with an anti-MT1-MMP antibody. These data suggest that MT1-MMP and the C6-MP are closely related or identical. When mouse 3T3 fibroblasts were transfected with MT1-MMP they acquired the ability to spread and migrate on the nonpermissive myelin substrate and to infiltrate into adult rat optic nerve explants. MT1-MMP-transfected fibroblasts and C6 glioma cells were able to digest bNI-220, one of the most potent CNS myelin inhibitory proteins. Plasma membranes of both MT1-MMP-transfected fibroblasts and C6 glioma cells inactivated inhibitory myelin extracts, and this activity was sensitive to the same protease inhibitors. Interestingly, pretreatment of CNS myelin with gelatinase A/MMP-2 could not inactivate its inhibitory property. These data imply an important role of MT1-MMP in spreading and migration of glioma cells on white matter constituents in vitro and point to a function of MT1-MMP in the invasive behavior of malignant gliomas in the CNS in vivo.

Membrane-type matrix metalloproteinases

Matrix metalloproteinases (MMP) degrade components of extracellular matrix (ECM), and thereby regulate formation, remodeling and maintenance of tissue. Abnormal function of cell surface proteases associated with malignant tumors may contribute directly to the invasive and malignant nature of the cells. Among the MMP's associated with the tumor cell surface, gelatinase A is believed to be particularly important, since it degrades type IV collagen, and is activated in a tumor specific manner, correlating with tumor spread and poor prognosis. Activation of pro-gelatinase A is uniquely regulated by a cell-mediated mechanism. This study describes an in vitro model that mimics the cell-surface activation mechanism. The expression of MT-MMP could not be detected in normal epithelial cells, but can be seen in transformed epithelial carcinoma cells.

Membrane-type metalloproteinases in tumor invasion

Matrix metalloproteinases (MMPs) are members of a multigene family of zinc-dependent enzymes involved in the degradation of numerous extracellular matrix (ECM) components. Among these enzymes, membrane-type MMPs (MT-MMPs) play a major role in the activation of progelatinase A (MMP-2). The molecular structure of these enzymes is characterized by a transmembrane domain and the presence of an insertion of 11 amino-acids between the pro-peptide and the catalytic domains, which may be cleaved by furin-like enzymes leading to the activated form of the enzymes. MT1-MMP appears to play a dual role in extracellular matrix remodeling through activation of progelatinase A and procollagenase 3 and direct cleavage of some ECM macromolecules such as gelatin, type I collagen and fibronectin. Tissue inhibitor of MMPs-2 (TIMP-2) serves as an intermediate in progelatinase A activation by binding to MT1-MMP and progelatinase A on the plasma membrane. In vivo, MT1-MMP is overexpressed in malignant tumor tissues in which it was mainly localized in stromal cells surrounding the neoplastic tissue. These peritumoral fibroblasts, under particular stimuli, would be induced to overexpress MT1-MMP and consequently activate gelatinase A leading to ECM degradation. The expression of MT1-MMP is however observed in vitro in the invasive tumor cells which might represent an late stage of tumor progression. All these data confirm the important role of MT-MMPs in tumor invasion and highlight a cooperation between tumor and stromal cells for the production of these enzymes. The contribution of MMPs in a metastatic process leads to the development of novel therapies using inhibitors of these enzymes. Among a multitude of synthetic inhibitors generated, Marimastat is already clinically employed in cancer treatment.

Membrane type 1-matrix metalloproteinase is involved in the formation of hepatocyte growth factor/scatter factor-induced branching tubules in madin-darby canine kidney epithelial cells

Matrix metalloproteinases (MMPs) are believed to be involved in morphogenesis. Association of MMPs in a model of kidney tubulogenesis was studied using Madin-Darby canine kidney (MDCK) epithelial cells in an in vitro morphogenetic system. MDCK cells form branching tubules in three-dimensional collagen gel matrix in the presence of hepatocyte growth factor (HGF). The addition of specific MMP inhibitor BB-94 and tissue inhibitor MMP (TIMP)-2 but not TIMP-1 to such collagen gel cultures reduced the formation of branching tubules induced by HGF. The induction of membrane-type 1-matrix metalloproteinase (MT1-MMP) mRNA expression was observed in MDCK cells cultured in the collagen gel. Stable expression of MT1-MMP antisense RNA interfered with the tubule formation of MDCK cells induced by HGF-collagen gel culture. These observations implicate MT1-MMP in kidney tubulogenesis and TIMP-2-specific inhibition suggests a direct role of MT1-MMP rather than a gelatinase A-mediated effect.

The role of myofibroblasts at the tumor border of invasive colorectal adenocarcinomas

BACKGROUND

In order to elucidate the significance of myofibroblasts in invasive growth of colorectal adenocarcinomas, we examined the number of myofibroblasts at the tumor border of colorectal adenocarcinomas.

METHOD

A total of 91 invasive colorectal adenocarcinomas were examined immunohistochemically using anti-alpha-smooth muscle actin (ASMA) and high-molecular-weight caldesmon (h-CD) antibodies; 25 carcinomas confined to the submucosa (sm carcinomas), 40 carcinomas confined to the muscularis propria (mp carcinomas) and 26 carcinomas invading the subserosa or adventitia (ss carcinomas). We considered ASMA-positive and h-CD-negative stromal cells as myofibroblasts.

RESULTS

Twenty-seven (67%) of the 40 mp carcinomas and 25 (96%) of the 26 ss carcinomas had a small number of myofibroblasts at the tumor border facing the muscularis propria.

CONCLUSIONS

Although direct evidence is lacking, there is a possibility that the further immediately vertical and radial invasion of carcinoma cells into the subserosa or adventitia is associated with a smaller number of myofibroblasts at the tumor border facing the muscularis propria in mp carcinomas, resulting in a low incidence of mp and a high incidence of ss carcinomas in the colorectum.

Production of trypsins by human gastric cancer cells correlates with their malignant phenotype

Proteolytic degradation of extracellular matrix is a critical step in tumour invasion and metastasis. To examine the role of trypsin in tumour dissemination, we cloned two variants (S4 and R3 cells) from STKM-1, a trypsinogen 1-producing diffuse gastric cancer cell line. Western blot analysis with antitrypsin antibody showed that 26 and 24 kDa proteins were highly detected in S4 conditioned medium (CM) in comparison to R3 CM. In addition to the 26 and 24 kDa proteins, 25 and 23 kDa bands, which correspond to enterokinase-activated trypsin, were found only in S4 CM. When the CMs of the two clones were treated with enterokinase, the 25 and 23 kDa trypsin activities in S4 CM were effectively increased as compared with R3 CM. When the two clones were inoculated intraperitoneally (i.p.) into nude mice, S4 cells strongly invaded the liver, pancreas and peritoneum and killed the hosts more rapidly than R3 cells: the 50% survival time was 50 days for S4 and 82 days for R3 cells. These results suggest that trypsin production is associated with the invasive growth of STKM-1 gastric cancer cells.

MT1-MMP and MMP-2 mRNA expression in human ovarian tumors: possible implications for the role of desmoplastic fibroblasts

Expression of activated MMP-2 (72 kDa type IV collagenase) is highly associated with the malignant phenotype in adenocarcinomas, but predominant expression of the mRNA appears to be in stromal cells. MT1-MMP (membrane type 1-matrix metalloproteinase) is implicated in tumor-epithelial cell surface activation of latent pro-MMP-2, indicating a mechanism for tumor-stromal interaction in invasion. We determined the relative mRNA distribution of these MMPs in human ovarian tumors with a view to analyzing potential variations in the epithelial-mesenchymal interactions dictating ovarian tumor cell spread. In situ hybridization using 35S-labeled riboprobes was used to analyze 33 human ovarian tumors and mouse xenografts of human ovarian (DOV 13, SKOV3) and breast (MCF 7) tumor cell lines known to express MT1-MMP and MMP-2. MMP-2 mRNA was expressed in 31 of 33 and MT1-MMP mRNA was expressed in 29 of 33 tumor cases. MMP-2 mRNA was predominantly expressed in desmoplastic fibroblasts and in the subepithelial stroma. MT1-MMP mRNA showed some colocalization with MMP-2 in stromal cells. Neoplastic epithelial cell labeling for MT1-MMP mRNA was present in borderline and malignant tumors but not in benign tumors, and was invariably less than stromal labeling. Xenografts of DOV 13, SKOV 3, and MCF 7 cells showed some stromal localization of MMP-2 mRNA and weak labeling of DOV 13 cells. There was variable labeling for MT1-MMP mRNA in the neoplastic cells only. The colocalization of MT1-MMP and MMP-2 mRNAs in ovarian carcinoma stroma supports the view that MT1-MMP is closely associated with MMP-2 expression and function. It suggests that either additional mechanisms are involved in regulating MMP-2 activation at the tumor cell surface, or more intriguingly, that desmoplastic fibroblasts may be the primary mediators of extracellular matrix remodeling with respect to this system.