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Blood vascular cells and lymphatic endothelial cells (BECs and LECs, respectively) form two separate vascular systems and are functionally distinct cell types or lineages with characteristic gene expression profiles. Interconversion between these cell types has not been reported. Here, we show that in conventional in vitro angiogenesis assays, human BECs of fetal or adult origin show altered gene expression that is indicative of transition to a lymphatic-like phenotype. This change occurs in BECs undergoing tubulogenesis in fibrin, collagen or Matrigel assays, but is independent of tube formation per se, because it is not inhibited by a metalloproteinase inhibitor that blocks tubulogenesis. It is also reversible, since cells removed from 3D tubules revert to a BEC expression profile upon monolayer culture. Induction of the lymphatic-like phenotype is partially inhibited by co-culture of HUVECs with perivascular cells. These data reveal an unexpected plasticity in endothelial phenotype, which is regulated by contact with the ECM environment and/or cues from supporting cells. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinase (MMP) 13 (collagenase 3) is an extracellular matrix remodeling enzyme that is induced in myofibroblasts during the earliest invasive stages of human breast carcinoma, suggesting that it is involved in tumor progression. During progression of mammary carcinomas in the polyoma virus middle T oncogene mouse model (MMTV-PyMT), Mmp13 mRNA was strongly upregulated concurrently with the transition to invasive and metastatic carcinomas. As in human tumors, Mmp13 mRNA was found in myofibroblasts of invasive grade II and III carcinomas, but not in benign grade I and II mammary intraepithelial neoplasias. To determine if MMP13 plays a role in tumor progression, we crossed MMTV-PyMT mice with Mmp13 deficient mice. The absence of MMP13 did not influence tumor growth, vascularization, progression to more advanced tumor stages, or metastasis to the lungs, and the absence of MMP13 was not compensated for by expression of other MMPs or tissue inhibitor of metalloproteinases. However, an increased fraction of thin collagen fibrils was identified in MMTVPyMT; Mmp13-/- compared to MMTV-PyMT;Mmp13+/+ tumors, showing that collagen metabolism was altered in the absence of MMP13.We conclude that the expression pattern ofMmp13 mRNA in myofibroblasts of invasive carcinomas in the MMTV-PyMT breast cancer model recapitulates the expression pattern observed in human breast cancer. Our results suggest thatMMP13 is a marker of carcinoma-associated myofibroblasts of invasive carcinoma, even though it does not make a major contribution to tumor progression in the MMTV-PyMT breast cancer model. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs) and adamalysins (ADAMs) cleave many extracellular proteins, including matrix, growth factors, and receptors. We profiled the RNA levels of every MMP, several ADAMs, and inhibitors of metalloproteinases (TIMPs and RECK) in numerous mouse tissues during development and in the uterus during pregnancy. Observations include: most secreted MMPs are expressed at low to undetectable levels in tissues, whereas membrane-bound MMPs, ADAMs and inhibitors are abundant; almost every proteinase and inhibitor is present in the uterus or placenta at some time during gestation; the mouse collagenases mColA and mColB are found exclusively in the uterus and testis; and each tissue has its unique signature of proteinase and inhibitor expression. [Copyright &y& Elsevier]

Abstract: The ADAMs (a disintegrin and metalloproteinase) are a fascinating family of transmembrane and secreted proteins with important roles in regulating cell phenotype via their effects on cell adhesion, migration, proteolysis and signalling. Though all ADAMs contain metalloproteinase domains, in humans only 13 of the 21 genes in the family encode functional proteases, indicating that at least for the other eight members, protein–protein interactions are critical aspects of their biological functions. The functional ADAM metalloproteinases are involved in “ectodomain shedding” of diverse growth factors, cytokines, receptors and adhesion molecules. The archetypal activity is shown by ADAM-17 (tumour necrosis factor-α convertase, TACE), which is the principal protease involved in the activation of pro-TNF-α, but whose sheddase functions cover a broad range of cell surface molecules. In particular, ADAM-17 is required for generation of the active forms of Epidermal Growth Factor Receptor (EGFR) ligands, and its function is essential for the development of epithelial tissues. Several other ADAMs have important sheddase functions in particular tissue contexts. Another major family member, ADAM-10, is a principal player in signalling via the Notch and Eph/ephrin pathways. For a growing number of substrates, foremost among them being Notch, cleavage by ADAM sheddases is essential for their subsequent “regulated intramembrane proteolysis” (RIP), which generates cleaved intracellular domains that translocate to the nucleus and regulate gene transcription. Several ADAMs play roles in spermatogenesis and sperm function, potentially by effecting maturation of sperm and their adhesion and migration in the uterus. Other non-catalytic ADAMs function in the CNS via effects on guidance mechanisms. The ADAM family are thus fundamental to many control processes in development and homeostasis, and unsurprisingly they are also linked to pathological states when their functions are dysregulated, including cancer, cardiovascular disease, asthma, Alzheimer’s disease. This review will provide an overview of current knowledge of the human ADAMs, discussing their structure, function, regulation and disease involvement. [Copyright &y& Elsevier]

P19CL6 are a clonal derivative of P19 embryonal carcinoma cells, a euploid, multipotent mouse cell line, that differentiate efficiently into cardiac myocytes, with spontaneous beating evident within 10 days, following DMSO treatment. Using real-time quantitative RT-PCR we have profiled the expression of the complete matrix metalloproteinase and tissue inhibitor of metalloproteinase gene families during P19CL6 differentiation to cardiac myocytes. The genes subdivide into eight groups based upon their expression profile. Their expression was both qualitatively and quantitatively highly homologous to that seen during mouse heart development. [Copyright &y& Elsevier]

Matrix metalloproteinase 8 (MMP-8) is a tumor-suppressive protease that cleaves numerous substrates, including matrix proteins and chemokines. In particular, MMP-8 proteolytically activates IL-8 and, thereby, regulates neutrophil chemotaxis in vivo. We explored the effects of expression of either a WT or catalytically inactive (E198A) mutant version of MMP-8 in human breast cancer cell lines. Analysis of serum-free conditioned media from three breast cancer cell lines (MCF-7, SKBR- 3, and MDA-MB-231) expressing WT MMP-8 revealed elevated levels of IL-6 and IL-8. This increase was mirrored at the mRNA level and was dependent on MMP-8 catalytic activity. However, sustained expression of WT MMP-8 by breast cancer cells was non-permissive for long-term growth, as shown by reduced colony formation compared with cells expressing either control vector or E198A mutant-MMP-8. In long-term culture of transfected MDA-MB-231 cells, expression of WT but not E198A mutant MMP-8 was lost, with IL-6 and IL-8 levels returning to base line. Rare clonal isolates of MDA-MB-231 cells expressing WT MMP-8 were generated, and these showed constitutively high levels of IL-6 and IL-8, although production of the interleukins was no longer dependent upon MMP-8 activity. These studies support a causal connection between MMP-8 activity and the IL-6/IL-8 network, with an acute response to MMP-8 involving induction of the proinflammatory mediators, which may in part serve to compensate for the deleterious effects of MMP-8 on breast cancer cell growth. This axis may be relevant to the recognized ability of MMP-8 to orchestrate the innate immune system in inflammation in vivo. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs) have been implicated in a variety of human diseases, including neuroimmunological disorders such as multiple sclerosis. However, the recent finding that some MMPs play paradoxical protective roles in these diseases has made necessary the detailed study of the specific function of each family member in their pathogenesis. To determine the relevance of collagenase-2 (MMP-8) in experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, we have performed two different analyses involving genetic and biochemical approaches. First, we have analyzed the development of EAE in mutant mouse deficient in MMP-8, with the finding that the absence of this proteolytic enzyme is associated with a marked reduction in the clinical symptoms of EAE. We have also found that MMP-8-/- mice exhibit a marked reduction in central nervous system-infiltrating cells and demyelinating lesions. As a second approach, we have carried out a pharmacological inhibition of MMP-8 with a selective inhibitor against this protease (IC50 = 0.4 nM). These studies have revealed that the administration of the MMP-8 selective inhibitor to mice with EAE also reduces the severity of the disease. Based on these findings, we conclude that MMP-8 plays an important role in EAE development and propose that this enzyme may be a novel therapeutic target in human neuro-inflammatory diseases such as multiple sclerosis. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the functional and clinical significance of integrin αvβ6 upregulation in myoepithelial cells of ductal carcinoma in situ (DCIS)., Experimental Design: Archival samples of DCIS and DCIS with associated invasion (n = 532) were analyzed for expression of αvβ6 by immunohistochemistry and ability to predict recurrence and progression assessed in an independent, unique cohort of DCIS cases with long-term follow-up. Primary myoepithelial cells and myoepithelial cell lines, with and without αvβ6 expression, were used to measure the effect of αvβ6 on growth and invasion of tumor cell lines in vitro and in a xenograft mouse model. Involvement of TGFβ signaling was established using mink lung epithelial cell (MLEC) assay and antibody inhibition, and expression and activation of matrix metalloproteinase (MMP)-9 established by Real Time-PCR and zymography., Results: Expression of αvβ6 is significantly associated with progression to invasive cancer (P < 0.006) and with recurrence over a median follow-up of 114 months in a series of matched DCIS cases treated with local excision. We show that expression of αvβ6 drives myoepithelial cells to promote tumor cell invasion in vitro and enhances mammary tumor growth in vivo. The tumor-promoting effect of αvβ6-positive myoepithelial cells is dependent on TGFβ-driven upregulation of MMP9 and can be abrogated by inhibiting this pathway., Conclusion: These findings indicate that altered myoepithelial cells in DCIS predict disease progression and recurrence and show that upregulation of αvβ6 on myoepithelial cells generates a tumor promoter function through TGFβ upregulation of MMP-9. These data suggest that expression of αvβ6 may be used to stratify patients with DCIS., (©2013 AACR.)

Vascular disrupting agents (VDA) offer a strategy to starve solid tumors of nutrients and oxygen concomitant with tumor shrinkage. Several VDAs have progressed into early clinical trials, but their therapeutic value seems to be compromised by systemic toxicity. In this report, we describe the design and characterization of a novel VDA, ICT2588, that is nontoxic until activated specifically in the tumor by membrane-type 1 matrix metalloproteinase (MT1-MMP). HT1080 cancer cells expressing MT1-MMP were selectively chemosensitive to ICT2588, whereas MCF7 cells that did not express MT1-MMP were nonresponsive. Preferential hydrolysis of ICT2588 to its active metabolite (ICT2552) was observed in tumor homogenates of HT1080 relative to MCF7 homogenates, mouse plasma, and liver homogenate. ICT2588 activation was inhibited by the MMP inhibitor ilomastat. In HT1080 tumor-bearing mice, ICT2588 administration resulted in the formation of the active metabolite, diminution of tumor vasculature, and hemorrhagic necrosis of the tumor. The antitumor activity of ICT2588 was superior to its active metabolite, exhibiting reduced toxicity, improved therapeutic index, enhanced pharmacodynamic effect, and greater efficacy. Coadministration of ICT2588 with doxorubicin resulted in a significant antitumor response (22.6 d growth delay), which was superior to the administration of ICT2588 or doxorubicin as a single agent, including complete tumor regressions. Our findings support the clinical development of ICT2588, which achieves selective VDA targeting based on MT-MMP activation in the tumor microenvironment.

Inflammatory tissue destruction is central to pathology in CNS tuberculosis (TB). We hypothesized that microglial-derived matrix metalloproteinases (MMPs) have a key role in driving such damage. Analysis of all of the MMPs demonstrated that conditioned medium from Mycobacterium tuberculosis-infected human monocytes (CoMTb) stimulated greater MMP-1, -3, and -9 gene expression in human microglial cells than direct infection. In patients with CNS TB, MMP-1/-3 immunoreactivity was demonstrated in the center of brain granulomas. Concurrently, CoMTb decreased expression of the inhibitors, tissue inhibitor of metalloproteinase-2, -3, and -4. MMP-1/-3 secretion was significantly inhibited by dexamethasone, which reduces mortality in CNS TB. Surface-enhanced laser desorption ionization time-of-flight analysis of CoMTb showed that TNF-alpha and IL-1beta are necessary but not sufficient for upregulating MMP-1 secretion and act synergistically to drive MMP-3 secretion. Chemical inhibition and promoter-reporter analyses showed that NF-kappaB and AP-1 c-Jun/FosB heterodimers regulate CoMTb-induced MMP-1/-3 secretion. Furthermore, NF-kappaB p65 and AP-1 c-Jun subunits were upregulated in biopsy granulomas from patients with cerebral TB. In summary, functionally unopposed, network-dependent microglial MMP-1/-3 gene expression and secretion regulated by NF-kappaB and AP-1 subunits were demonstrated in vitro and, for the first time, in CNS TB patients. Dexamethasone suppression of MMP-1/-3 gene expression provides a novel mechanism explaining the benefit of steroid therapy in these patients.

Purpose: Head and neck squamous cell carcinomas (HNSCC) are characterized by high morbidity and mortality, largely due to the high invasive and metastatic potential of these tumors, high recurrence rates, and low treatment responses. Proteinases have been implicated in several aspects of tumor growth and metastasis in a broad range of tumors including HNSCC., Experimental Design: Comprehensive expression profiling of proteinases [matrix metalloproteinases (MMPs), A disintegrin and metalloproteinase (ADAMs), and ADAMs with thrombospondin motif (ADAMTSs)] and their inhibitors [tissue inhibitor of metalloproteinases (TIMPs)] was done using quantitative real-time reverse transcription-PCR analysis of a large cohort of tissue samples representing the tumor (n = 83), the invasive margin (n = 41), and the adjacent tissue (n = 41) from 83 HNSCC patients, along with normal tissue controls (n = 13), as well as cell lines established from tumors of 34 HNSCC patients., Results: The results show specifically elevated gene expression of several proteinases, including MMP1, MMP3, MMP10, and MMP13 within tumor tissue and peritumoral adjacent tissue. In addition, the results identify several novel HNSCC-associated proteinases, including ADAM8, ADAM9, ADAM17, ADAM28, ADAMTS1, ADAMTS8, and ADAMTS15. There were also significant differences in proteinase expression based on clinical parameters, i.e., tumor location, grade, and local invasion. MMP13 expression was significantly higher in large (>4 cm) locally invasive tumors (P < 0.05). MMP9 expression was significantly decreased in tumors with regional metastasis, whereas increased expression of ADAM8 was noted in the metastatic tumors (P < 0.001 for both)., Conclusions: These findings suggest the HNSCC degradome as a valuable source of diagnostic, predictive, and prognostic molecular markers for these malignant tumors., (Copyright 2010 AACR.)

Quantitative reverse transcriptase polymerase chain reaction enables the accurate quantification of gene expression in cultured cells or small tissue samples. In this chapter, we describe the use of Taqman((R)) technology to measure expression of matrix metalloproteinases and related genes.

Brk, a tyrosine kinase expressed in a majority of breast tumors, but not normal mammary tissue, promotes breast carcinoma cell proliferation. Normal epithelial cells are dependent on cell-cell or cell-matrix interactions for survival and undergo apoptosis after disruption of these interactions. Tumor cells are less sensitive to the induction of apoptosis and are predicted to have the potential to disseminate. We investigated whether Brk has further roles in breast tumor progression by relating its expression to tumor grade and demonstrating its role in the regulation of carcinoma cell survival under non-adherent conditions. Brk expression was determined by reverse transcription PCR on RNA extracted from surgical samples of human breast cancers. Breast carcinoma cell survival in suspension culture was examined when Brk protein levels were suppressed by RNA interference. Additionally, the effect of experimentally overexpressing Brk in otherwise Brk-negative breast carcinoma cells was assessed. Brk mRNA expression was notably higher in grade 3 breast tumors, as compared with lower tumor grades. In suspension culture, Brk suppression increased the rate of cell death, as compared with controls, and this cell death program exhibited characteristics of autophagy but not of apoptosis. Conversely, experimental expression of Brk in Brk-negative cells increased cell survival whereas kinase-inactive Brk did not. Therefore, Brk enhances breast carcinoma cell survival in suspension, suggesting a role for Brk in supporting breast cancer cell dissemination.

Objective: Impairment of transforming growth factor (TGF)-beta1 signaling accelerates atherosclerosis in experimental mice. However, it is uncertain whether increased TGF-beta1 expression would retard atherosclerosis. The role of TGF-beta1 in aneurysm formation is also controversial. We tested whether overexpression of active TGF-beta1 in hyperlipidemic mice affects atherogenesis and aortic dilation., Methods and Results: We generated apolipoprotein E-null mice with transgenes that allow regulated overexpression of active TGF-beta1 in their hearts. Compared to littermate controls, these mice had elevated cardiac and plasma TGF-beta1, less aortic root atherosclerosis (P< or =0.002), fewer lesions in the thoracic and abdominal aortae (P< or =0.01), less aortic root dilation (P<0.001), and fewer pseudoaneurysms (P=0.02). Mechanistic studies revealed no effect of TGF-beta1 overexpression on plasma lipids or cytokines, or on peripheral lymphoid organ cells. However, aortae of TGF-beta1-overexpressing mice had fewer T-lymphocytes, more collagen, less lipid, lower expression of inflammatory cytokines and matrix metalloproteinase-13, and higher expression of tissue inhibitor of metalloproteinase-2., Conclusions: When overexpressed in the heart and plasma, TGF-beta1 is an antiatherogenic, vasculoprotective cytokine that limits atherosclerosis and prevents aortic dilation. These actions are associated with significant changes in cellularity, collagen and lipid accumulation, and gene expression in the artery wall.

MHC class I-related chain (MIC) A/B are transmembrane proteins expressed in pathological conditions that are ligands for the activating receptor NKG2D found on cytotoxic lymphocytes. Soluble NKG2D ligands are detected in sera of patients suffering from multiple types of cancer where they are associated with reduced levels of receptor expression and compromised function of NK and CTLs. In this study, we report the identification of a metalloproteinase involved in the cleavage process of MIC; inhibition and knockdown of ADAM17/TACE blocks the shedding of these proteins. Strikingly, the recruitment of both enzyme and substrate to detergent-resistant membrane microdomains is crucial for efficient proteolysis. These findings provide a novel insight into the molecular mechanisms of MIC shedding.

Introduction: The molecular mechanisms underlying cartilage destruction in osteoarthritis are poorly understood. Proteolysis is a key feature in the turnover and degradation of cartilage extracellular matrix where the focus of research has been on the metzincin family of metalloproteinases. However, there is strong evidence to indicate important roles for other catalytic classes of proteases, with both extracellular and intracellular activities. The aim of this study was to profile the expression of the majority of protease genes in all catalytic classes in normal human cartilage and that from patients with osteoarthritis (OA) using a quantitative method., Methods: Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur (NOF). Total RNA was purified, and expression of genes assayed using Taqman low-density array quantitative RT-PCR., Results: A total of 538 protease genes were profiled, of which 431 were expressed in cartilage. A total of 179 genes were differentially expressed in OA versus NOF cartilage: eight aspartic proteases, 44 cysteine proteases, 76 metalloproteases, 46 serine proteases and five threonine proteases. Wilcoxon ranking as well as the LogitBoost-NR machine learning approach were used to assign significance to each gene, with the most highly ranked genes broadly similar using each method., Conclusions: This study is the most complete quantitative analysis of protease gene expression in cartilage to date. The data help give direction to future research on the specific function(s) of individual proteases or protease families in cartilage and may help to refine anti-proteolytic strategies in OA.

Introduction: The stromal microenvironment has a profound influence on tumour cell behaviour. In tumours, the extracellular matrix (ECM) composition differs from normal tissue and allows novel interactions to influence tumour cell function. The ECM protein tenascin-C (TNC) is frequently up-regulated in breast cancer and we have previously identified two novel isoforms - one containing exon 16 (TNC-16) and one containing exons 14 plus 16 (TNC-14/16)., Methods: The present study has analysed the functional significance of this altered TNC isoform profile in breast cancer. TNC-16 and TNC-14/16 splice variants were generated using PCR-ligation and over-expressed in breast cancer cells (MCF-7, T47D, MDA-MD-231, MDA-MB-468, GI101) and human fibroblasts. The effects of these variants on tumour cell invasion and proliferation were measured and compared with the effects of the large (TNC-L) and fully spliced small (TNC-S) isoforms., Results: TNC-16 and TNC-14/16 significantly enhanced tumour cell proliferation (P < 0.05) and invasion, both directly (P < 0.01) and as a response to transfected fibroblast expression (P < 0.05) with this effect being dependent on tumour cell interaction with TNC, because TNC-blocking antibodies abrogated these responses. An analysis of 19 matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases 1 to 4 (TIMP 1 to 4) revealed that TNC up-regulated expression of MMP-13 and TIMP-3 two to four fold relative to vector, and invasion was reduced in the presence of MMP inhibitor GM6001. However, this effect was not isoform-specific but was elicited equally by all TNC isoforms., Conclusions: These results demonstrate a dual requirement for TNC and MMP in enhancing breast cancer cell invasion, and identify a significant role for the tumour-associated TNC-16 and TNC-14/16 in promoting tumour invasion, although these isoform-specific effects appear to be mediated through MMP-independent mechanisms.

Prostate cancer cells exist under hypoxic conditions. Hypoxia has a detrimental effect on the efficacy of treatment and final outcome in patients with prostate cancer. There have been a large number of endogenous markers of hypoxia described previously across a range of cancer types, both in vitro and in vivo. The aim of this study was to evaluate the expression of a range of hypoxia-associated genes within benign prostatic hypertrophy (BPH) and prostate cancer tissue. Messenger RNA was extracted from primary prostate tissue obtained from 67 men with benign prostatic hypertrophy or prostate cancer (Gleason score 5 to 10). Real-time polymerase chain reaction was performed to quantify the expression levels of 12 hypoxia-associated genes in these tissues. Expression of lysyl oxidase (LOX) and glucose transporter-1 (GLUT-1) genes were significantly higher in prostate cancer compared with BPH tissue (P<0.05) and correlated with Gleason score (LOX: R=0.297, P=0.015; GLUT-1: R=0.274, P=0.026). HIF-2alpha had a negative correlation with Gleason score (R= -0.309, P=0.012). The remaining hypoxia-associated genes did not show any specific pattern of expression in prostate tissue. Numerous molecules have been proposed as endogenous markers of hypoxia. The findings of this study illustrate that not all hypoxia-associated molecules are relevant to prostate cancer in vivo. However, LOX and GLUT-1 are candidate markers of hypoxia in prostate cancer and may prove useful in identifying patients with hypoxic prostate cancer. Not all hypoxia-associated molecules are relevant in prostate cancer in vivo.

Collagenase-2 (matrix metalloproteinase-8, MMP-8) is an MMP mainly produced by neutrophils and associated with many inflammatory conditions. We have previously described that MMP-8 plays a protective role in cancer through its ability to regulate the inflammatory response induced by carcinogens. Moreover, it has been reported that experimental manipulation of the expression levels of this enzyme alters the metastatic behavior of human breast cancer cells. In this work, we have used mutant mice deficient in MMP-8 and syngenic melanoma and lung carcinoma tumor cells lines overexpressing this enzyme to further explore the putative antimetastatic potential of MMP-8. We report herein that MMP-8 prevents metastasis formation through the modulation of tumor cell adhesion and invasion. Thus, tumor cells overexpressing MMP-8 have an increased adhesion to extracellular matrix proteins, whereas their invasive ability through Matrigel is substantially reduced when compared with control cells. Analysis of MMP-8 in breast cancer patients revealed that the expression of this metalloproteinase by breast tumors correlates with a lower incidence of lymph node metastasis and confers good prognosis to these patients. On this basis, we propose that MMP-8 is a tumor protective factor, which also has the ability to reduce the metastatic potential of malignant cells in both mice and human.

Adamalysins [a disintegrin and metalloproteinase (ADAM)] are a family of cell surface transmembrane proteins that have broad biological functions encompassing proteolysis, adhesion, and cell signal regulation. We previously showed that the cytoplasmic domain of ADAM-15 interacts with Src family protein tyrosine kinases and the adaptor protein growth factor receptor binding protein 2 (Grb2). In the present study, we have cloned and characterized four alternatively spliced forms of ADAM-15, which differ only in their cytoplasmic domains. We show that the four ADAM-15 variants were differentially expressed in human mammary carcinoma tissues compared with normal breast. The expression of the individual isoforms did not correlate with age, menopausal status, tumor size or grade, nodal status, Nottingham Prognostic Index, or steroid hormone receptor status. However, higher levels of two isoforms (ADAM-15A and ADAM-5B) were associated with poorer relapse-free survival in node-negative patients, whereas elevated ADAM-15C correlated with better relapse-free survival in node-positive, but not in node-negative, patients. The expression of ADAM-15A and ADAM-15B variants in MDA-MB-435 cells had differential effects on cell morphology, with adhesion, migration, and invasion enhanced by expression of ADAM-15A, whereas ADAM-15B led to reduced adhesion. Using glutathione S-transferase pull-down assays, we showed that the cytoplasmic domains of ADAM-15A, ADAM-15B, and ADAM-15C show equivalent abilities to interact with extracellular signal-regulated kinase and the adaptor molecules Grb2 and Tks5/Fish, but associate in an isoform-specific fashion with Nck and the Src and Brk tyrosine kinases. These data indicate that selective expression of ADAM-15 variants in breast cancers could play an important role in determining tumor aggressiveness by interplay with intracellular signaling pathways.

Balanced expression of proteases and their inhibitors is one prerequisite of tissue homeostasis. Metastatic spread of tumor cells through the organism depends on proteolytic activity and is the death determinant for cancer patients. Paradoxically, increased expression of tissue inhibitor of metalloproteinases-1 (TIMP-1), a natural inhibitor of several endometalloproteinases, including matrix metalloproteinases and a disintegrin and metalloproteinase-10 (ADAM-10), in cancer patients is negatively correlated with their survival, although TIMP-1 itself inhibits invasion of some tumor cells. Here, we show that elevated stromal expression of TIMP-1 promotes liver metastasis in two independent tumor models by inducing the hepatocyte growth factor (HGF) signaling pathway and expression of several metastasis-associated genes, including HGF and HGF-activating proteases, in the liver. We also found in an in vitro assay that suppression of ADAM-10 is in principle able to prevent shedding of cMet, which may be one explanation for the increase of cell-associated HGF receptor cMet in livers with elevated TIMP-1. Similar TIMP-1-associated changes in gene expression were detected in livers of patients with metastatic colorectal cancer. The newly identified role of TIMP-1 to create a prometastatic niche may also explain the TIMP-1 paradoxon.

Purpose: Matrix metalloproteinases (MMPs) and the tissue inhibitors of the MMPs (TIMPs) have been implicated in lens differentiation, growth, remodeling, and cataract. Hence, a gene expression analysis was undertaken in epithelial and fiber cells dissected from clear human donor lenses., Methods: The human lens was dissected into three regions: anterior epithelial, equatorial, and fiber cells. Primary lens cell cultures were also analyzed. cDNA was generated by reverse transcription of the mRNA portion of the total RNA isolated from each sample. Gene expression data were generated using quantitative real-time reverse transcription PCR. Data were analyzed in terms of cycle threshold number (C(T)) and were normalized to endogenous 18S expression. Western blot analyses were carried out to confirm the presence of two critical MMPs., Results: Anterior and equatorial samples were uncontaminated by fiber cells because they showed high expression of alpha-crystallin genes but low expression of beta- and gamma-crystallins. The fibers had high expression of these genes and of MIP. MMP genes were expressed at uniformly low levels in the native tissues except for MMP-14 and -15 (MT1- and MT2-MMP, respectively). In fact, MT1-MMP declined in expression from the anterior epithelium to fibers, whereas MT2-MMP increased. The presence of MT1 and MT2-MMP proforms and faster migrating bands, indicating processed or activated forms, was confirmed at the protein level. TIMP genes were uniformly highly expressed in native tissues, with TIMP-3 having the highest expression in the epithelial tissues and TIMP-2 in the fibers. MMP expression was generally elevated in both sets of cultured cells, including MMP-2 and -9. TIMP genes were also relatively highly expressed in the cultured cells., Conclusions: MMP expression is generally well regulated in native tissues, with relatively low expression of MMPs and high expression of TIMPs. Membrane-type MMPs (MT1 and 2-MMPs) were the most highly expressed; this is important in a tissue with relatively high membrane content but low extracellular space. The striking reciprocal patterns of expression of MT1-MMP and MT2-MMP indicate that these enzymes are of particular significance in lens function.

Membrane-type matrix metalloproteinases (MT-MMP) constitute a subfamily of six distinct membrane-associated MMPs. Although the contribution of MT1-MMP during different steps of cancer progression has been well documented, the significance of other MT-MMPs is rather unknown. We have investigated the involvement of MT4-MMP, a glycosylphosphatidylinositol-anchored protease, in breast cancer progression. Interestingly, immunohistochemical analysis shows that MT4-MMP production at protein level is strongly increased in epithelial cancer cells of human breast carcinomas compared with normal epithelial cells. Positive staining for MT4-MMP is also detected in lymph node metastases. In contrast, quantitative reverse transcription-PCR analysis reveals similar MT4-MMP mRNA levels in human breast adenocarcinomas and normal breast tissues. Stable transfection of MT4-MMP cDNA in human breast adenocarcinoma MDA-MB-231 cells does not affect in vitro cell proliferation or invasion but strongly promotes primary tumor growth and associated metastases in RAG-1 immunodeficient mice. We provide for the first time evidence that MT4-MMP overproduction accelerates in vivo tumor growth, induces enlargement of i.t. blood vessels, and is associated with increased lung metastases. These results identify MT4-MMP as a new putative target to design anticancer strategies.

Circulating B cells enter the CNS as part of normal immune surveillance and in pathologic states, including the common and disabling illness multiple sclerosis. However, little is known about the molecular mechanisms that mediate human B cell interaction with the specialized brain endothelial cells comprising the blood-brain barrier (BBB). We studied the molecular mechanisms that regulate the migration of normal human B cells purified ex vivo, across human adult brain-derived endothelial cells (HBECs). We found that B cells migrated across HBECs more efficiently than T cells from the same individuals. B cell migration was significantly inhibited by blocking Abs to the adhesion molecules ICAM-1 and VLA-4, but not VCAM-1, similar to the results previously reported for T cells. Blockade of the chemokines monocyte chemoattractant protein-1 and IL-8, but not RANTES or IFN-gamma-inducible protein-10, significantly inhibited B cell migration, and these results were correlated with the chemokine receptor expression of B cells measured by flow cytometry and by RNase protection assay. Tissue inhibitor of metalloproteinase-1, a natural inhibitor of matrix metalloproteinases, significantly decreased B cell migration across the HBECs. A comprehensive RT-PCR comparative analysis of all known matrix metalloproteinases and tissue inhibitors of metalloproteinases in human B and T cells revealed distinct profiles of expression of these molecules in the different cell subsets. Our results provide insights into the molecular mechanisms that underlie human B cell migration across the BBB. Furthermore, they identify potential common, and unique, therapeutic targets for limiting CNS B cell infiltration and predict how therapies currently developed to target T cell migration, such as anti-VLA-4 Abs, may impact on B cell trafficking.

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate proteolysis of the extracellular matrix and other extracellular proteins, including growth factors and their receptors. The aberrant expression of these genes is common in most cancers. We profiled the RNA levels of every human MMP and TIMP in a variety of cell types (fibroblast, endothelial, hematopoietic, carcinoma, melanoma, and glioma) using quantitative PCR, with the aim of identifying novel expression patterns. Almost all members of the membrane-type (MT-) MMP and TIMP families were elevated in glioma lines compared to carcinomas. In clinical glioma specimens, there were positive correlations between glioma grade and RNA levels of MT-1, MT-2, and MT-6 MMP, TIMP-1 and TIMP-2, and for several growth factors and receptors. These findings suggest that advanced malignant gliomas have elevated levels of membrane-associated MMPs and TIMPs, which may potentially regulate vascularization and invasion. Concurrent elevation of signaling molecules suggests potential bidirectional relationships that enhance tumor aggressiveness.