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

Untangling the web of glioblastoma treatment resistance using a multi-omic and multidisciplinary approach

Glioblastoma (GBM), the most common human brain tumor, has been notoriously resistant to treatment. As a result, the dismal overall survival of GBM patients has not changed over the past three decades. GBM has been stubbornly resistant to checkpoint inhibitor immunotherapies, which have been remarkably effective in the treatment of other tumors. It is clear that GBM resistance to therapy is multifactorial. Although therapeutic transport into brain tumors is inhibited by the blood brain barrier, there is evolving evidence that overcoming this barrier is not the predominant factor. GBMs generally have a low mutation burden, exist in an immunosuppressed environment and they are inherently resistant to immune stimulation, all of which contribute to treatment resistance. In this review, we evaluate the contribution of multi-omic approaches (genomic and metabolomic) along with analyzing immune cell populations and tumor biophysical characteristics to better understand and overcome GBM multifactorial resistance to treatment.

The extracellular matrix - immune microenvironment crosstalk in cancer therapy: Challenges and opportunities

Targeting the tumour immune microenvironment (TIME) by cancer immunotherapy has led to improved patient outcomes. However, response to these treatments is heterogeneous and cancer-type dependant. The therapeutic activity of classical cancer therapies such as chemotherapy, radiotherapy, and surgical oncology is modulated by alterations of the TIME. A major regulator of immune cell function and resistance to both immune and classical therapies is the extracellular matrix (ECM). Concurrently, cancer therapies reshape the TIME as well as the ECM, causing both pro- and anti-tumour responses. Accordingly, the TIME-ECM crosstalk presents attractive opportunities to improve therapy outcomes. Here, we review the molecular crosstalk between the TIME and the ECM in cancer and its implications in cancer progression and clinical intervention. Additionally, we discuss examples and future directions of ECM and TIME co-targeting in combination with oncological therapies including surgery, chemotherapy, and radiotherapy.

Cellular mechanotransduction in health and diseases: from molecular mechanism to therapeutic targets

Cellular mechanotransduction, a critical regulator of numerous biological processes, is the conversion from mechanical signals to biochemical signals regarding cell activities and metabolism. Typical mechanical cues in organisms include hydrostatic pressure, fluid shear stress, tensile force, extracellular matrix stiffness or tissue elasticity, and extracellular fluid viscosity. Mechanotransduction has been expected to trigger multiple biological processes, such as embryonic development, tissue repair and regeneration. However, prolonged excessive mechanical stimulation can result in pathological processes, such as multi-organ fibrosis, tumorigenesis, and cancer immunotherapy resistance. Although the associations between mechanical cues and normal tissue homeostasis or diseases have been identified, the regulatory mechanisms among different mechanical cues are not yet comprehensively illustrated, and no effective therapies are currently available targeting mechanical cue-related signaling. This review systematically summarizes the characteristics and regulatory mechanisms of typical mechanical cues in normal conditions and diseases with the updated evidence. The key effectors responding to mechanical stimulations are listed, such as Piezo channels, integrins, Yes-associated protein (YAP) /transcriptional coactivator with PDZ-binding motif (TAZ), and transient receptor potential vanilloid 4 (TRPV4). We also reviewed the key signaling pathways, therapeutic targets and cutting-edge clinical applications of diseases related to mechanical cues.

Targeting the tumor biophysical microenvironment to reduce resistance to immunotherapy

Immunotherapy based on immune checkpoint inhibitors has evolved into a new pillar of cancer treatment in clinics, but dealing with treatment resistance (either primary or acquired) is a major challenge. The tumor microenvironment (TME) has a substantial impact on the pathological behaviors and treatment response of many cancers. The biophysical clues in TME have recently been considered as important characteristics of cancer. Furthermore, there is mounting evidence that biophysical cues in TME play important roles in each step of the cascade of cancer immunotherapy that synergistically contribute to immunotherapy resistance. In this review, we summarize five main biophysical cues in TME that affect resistance to immunotherapy: extracellular matrix (ECM) structure, ECM stiffness, tumor interstitial fluid pressure (IFP), solid stress, and vascular shear stress. First, the biophysical factors involved in anti-tumor immunity and therapeutic antibody delivery processes are reviewed. Then, the causes of these five biophysical cues and how they contribute to immunotherapy resistance are discussed. Finally, the latest treatment strategies that aim to improve immunotherapy efficacy by targeting these biophysical cues are shared. This review highlights the biophysical cues that lead to immunotherapy resistance, also supplements their importance in related technologies for studying TME biophysical cues in vitro and therapeutic strategies targeting biophysical cues to improve the effects of immunotherapy.

TRIM66 hastens the malignant progression of non-small cell lung cancer via modulating MMP9-mediated TGF-β/SMAD pathway

OBJECTIVE

To investigate regulatory function and underlying mechanism of TRIM66 in non-small cell lung cancer (NSCLC).

METHODS

TRIM66 and MMP9 expression in NSCLC cells and tissues was assayed via qRT-PCR and western blot. CCK-8, colony formation, Transwell and flow cytometry assays were conducted to measure cell functional alternations in NSCLC. Western blot was employed to measure expression as well as phosphorylation levels of epithelial-mesenchymal transition-(EMT) and TGF-β/SMAD pathways-related proteins. Co-immunoprecipitation (Co-IP) assay was done to probe interaction between TRIM66 and MMP9. Xenograft in vivo experiment and tumor metastasis model in nude mice were utilized to investigate effects of TRIM66 on tumor growth of NSCLC.

RESULTS

TRIM66 and MMP9 were conspicuously highly expressed in NSCLC cells and tissues. High TRIM66 level was markedly correlated with metastasis. Silencing TRIM66 prominently repressed the proliferation, migration and invasion of transfected cells, while inducing cell apoptosis. Whereas forced expression of TRIM66 exerted the opposite effect. The aberrant expression of TRIM66 modulated EMT pathway. TRIM66 also regulated MMP9 expression, and the interaction between them was validated by Co-IP assay. Overexpression of MMP9 could activate TGF-β/SMAD pathway. Rescue experiments manifested that si-MMP9 or SB431542 could partially reverse phenotypes induced by TRIM66. In vivo experiments revealed that silencing TRIM66 could hamper NSCLC tumor growth and metastasis.

CONCLUSION

TRIM66 and MMP9 were up-regulated in NSCLC. TRIM66 facilitated the malignant progression of NSCLC through modulating MMP9-mediated TGF-β/SMAD pathway.

Cell surface cathepsin G activity differs between human natural killer cell subsets

Natural killer (NK) cells are critical in diverse defense mechanisms, including elimination of viral infected cells and destruction of tumor cells. NK cells are characterized by the ability to initiate apoptosis in target cells when their cell surface major histocompatibility complex class I (MHC I) repertoire is missing. On the other hand, NK cells are not activated when MHC I or non-classical MHC molecules are found on the respective cells. It was demonstrated that cathepsin G (CatG) binds to the cell surface of NK cells; however, the distribution of this protease on the cell surface of NK cell subsets has not been identified. Here, we show that CatG cell surface level differs between NK cell subsets. CatG was determined on the protein- and activity level (activity-based probe MARS116) by using flow cytometry. Thus, MARS116 is a novel reporter of cell surface CatG activity and can be used to differentiate between distinct NK cell subsets.

In Vitro Assessment of Human Natural Killer Cell Migration and Invasion

Cell invasion assays are important to obtain valuable functional data relating to tissue migration and invasion of effector lymphocytes. Boyden chamber invasion assays represent a reductionist system that allows for easy manipulation using various extracellular matrix (ECM) components addressing migratory functions or invasion into/through a three-dimensional matrix where migration and invasion inhibitors as well as stimulators can be added. Presented here is a description using the Transwell(®) system where invasion and migration can be studied. It constitutes an inner cell culture well with a (PET) polycarbonate filter with 3-8 μm pores that allow for cells to transverse to the bottom chamber where they can be recorded by various methods (Fig. 1). The polycarbonate filters may be coated with ECM proteins for migration and adhesive studies or covered with a thick layer that occludes the pores to address matrix degradation, i.e., invasion as described in this chapter.

Expression kinetics of metalloproteinases and their tissue inhibitors in experimental murine pulmonary tuberculosis

AIM

Explore the temporal expression of metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) during experimental tuberculosis induced by virulent Mycobacterium tuberculosis strain H37Rv.

METHODS

BALB/c mice were infected via endotracheal instillation with H37Rv. Groups of mice were euthanized at different time points during infection. RNA was isolated from the lungs, and the expression of MMP-3, 8, 9, 10, 12, 13 and TIMP-1-4 was determined by quantitative PCR. Immunohistochemical detection of MMP-3, MMP-9, and MMP-10 was done to determine the cell source.

RESULTS

The infection with H37Rv-induced inflammation resulted in maximal up-regulation of MMP-3, 8, 9, 10, 12 and 13 at day 21 postinfection. Additionally, MMP-13 showed another expression peak during late disease at day 60. Airway epithelium and macrophages were the most common MMP-3 and MMP-9 immunopositive cells, while for MMP-10, macrophages and endothelial cells were the most common, particularly at days 14 and 21 in well-formed granulomas. During late disease, vacuolated macrophages in pneumonic areas and bronchial epithelium showed mild MMP immunostaining.

CONCLUSIONS

MMP-3, 8, 9, 10, 12, and 13 are maximally expressed at the peak of granuloma formation in the mouse tuberculosis model, with no compensation in levels or timing of TIMP expression. This data opens the possibility of participation of these molecules in the granuloma process.

NK cell autoreactivity and autoimmune diseases

Increasing evidences have pointed out the relevance of natural killer (NK) cells in organ-specific and systemic autoimmune diseases. NK cells bear a plethora of activating and inhibiting receptors that can play a role in regulating reactivity with autologous cells. The activating receptors recognize natural ligands up-regulated on virus-infected or stressed or neoplastic cells. Of note, several autoimmune diseases are thought to be linked to viral infections as one of the first event in inducing autoimmunity. Also, it is conceivable that autoimmunity can be triggered when a dysregulation of innate immunity occurs, activating T and B lymphocytes to react with self-components. This would imply that NK cells can play a regulatory role during adaptive immunity; indeed, innate lymphoid cells (ILCs), comprising the classical CD56⁺ NK cells, have a role in maintaining or alternating tissue homeostasis secreting protective and/or pro-inflammatory cytokines. In addition, NK cells display activating receptors involved in natural cytotoxicity and the activating isoforms of receptors for HLA class I that can interact with healthy host cells and induce damage without any evidence of viral infection or neoplastic-induced alteration. In this context, the interrelationship among ILC, extracellular-matrix components, and mesenchymal stromal cells can be considered a key point for the control of homeostasis. Herein, we summarize evidences for a role of NK cells in autoimmune diseases and will give a point of view of the interplay between NK cells and self-cells in triggering autoimmunity.

Membrane-type matrix metalloproteinases: key mediators of leukocyte function

Leukocytes are major cellular effectors of the immune response. To accomplish this task, these cells display a vast arsenal of proteinases, among which, members of the MMP family are especially important. Leukocytes express several members of the MMP family, including secreted- and membrane-anchored MT- MMPs, which synergistically orchestrate an appropriate proteolytic reaction that ultimately modulates immunological responses. The MT-MMP subfamily comprises TM- and GPI-anchored proteinases, which are targeted to well-defined membrane microdomains and exhibit different substrate specificities. Whereas much information exists on the biological roles of secreted MMPs in leukocytes, the roles of MT-MMPs remain relatively obscure. This review summarizes the current knowledge on the expression of MT-MMPs in leukocyte and their contribution to the immune responses and to pathological conditions.

Fibrosis-dependent mechanisms of hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a rising worldwide cause of cancer mortality, making the elucidation of its underlying mechanisms an urgent priority. The liver is unique in its response to injury, simultaneously undergoing regeneration and fibrosis. HCC occurs in the context of these two divergent responses, leading to distinctive pathways of carcinogenesis. In this review we highlight pathways of liver tumorigenesis that depend on, or are enhanced by, fibrosis. Activated hepatic stellate cells drive fibrogenesis, changing the composition of the extracellular matrix. Matrix quantity and stiffness also increase, providing a reservoir for bound growth factors. In addition to promoting angiogenesis, these factors may enhance the survival of both preneoplastic hepatocytes and activated hepatic stellate cells. Fibrotic changes also modulate the activity of inflammatory cells in the liver, reducing the activity of natural killer and natural killer T cells that normally contribute to tumor surveillance. These pathways synergize with inflammatory signals, including telomerase reactivation and reactive oxygen species release, ultimately resulting in cancer. Clarifying fibrosis-dependent tumorigenic mechanisms will help rationalize antifibrotic therapies as a strategy to prevent and treat HCC.

Loss of epidermal MMP-14 expression interferes with angiogenesis but not with re-epithelialization

Synthesis and activation of matrix metalloproteinases during wound healing are important for remodeling the extracellular matrix and modulating various cellular functions. The membrane-type 1 matrix metalloproteinase (MMP-14) has been shown to play a key role during these processes. To analyze the function of epidermal-derived MMP-14 during skin repair we generated mice lacking MMP-14 expression in the epidermis (MMP-14(ep-/-)). These mice displayed overall normal skin morphology and epidermal differentiation patterns. Wound repair in MMP-14(ep-/-) followed the same kinetics as in wild type mice (MMP-14(ep+/+)), and infiltration of neutrophils, leukocytes, and macrophages into the wound site was comparable. Microscopic analysis showed no altered re-epithelialization in the absence of epidermal MMP-14. Furthermore, epidermal differentiation at the end of the repair process and scar formation was normal. However, at day 14 post wounding, sustained angiogenesis was observed in MMP-14(ep-/-) mice in contrast to control mice. Interestingly, decreased levels of endostatin were detected in wound lysates of MMP-14(ep-/-) mice as well as in cultured keratinocytes. Taken together, these data indicate that MMP-14 expression in keratinocytes is dispensable for skin homeostasis and repair, but plays a crucial role in the epidermal-dermal crosstalk leading to modulation of vessel density.

Nuclear localization of matrix metalloproteinases

Matrix metalloproteinases (MMPs) were originally identified as matrixin proteases that act in the extracellular matrix. Recent works have uncovered nontraditional roles for MMPs in the extracellular space as well as in the cytosol and nucleus. There is strong evidence that subspecialized and compartmentalized matrixins participate in many physiological and pathological cellular processes, in which they can act as both degradative and regulatory proteases. In this review, we discuss the transcriptional and translational control of matrixin expression, their regulation of intracellular sorting, and the structural basis of activation and inhibition. In particular, we highlight the emerging roles of various matrixin forms in diseases. The activity of matrix metalloproteinases is regulated at several levels, including enzyme activation, inhibition, complex formation and compartmentalization. Most MMPs are secreted and have their function in the extracellular environment. MMPs are also found inside cells, both in the nucleus, cytosol and organelles. The role of intracellular located MMPs is still poorly understood, although recent studies have unraveled some of their functions. The localization, activation and activity of MMPs are regulated by their interactions with other proteins, proteoglycan core proteins and / or their glycosaminoglycan chains, as well as other molecules. Complexes formed between MMPs and various molecules may also include interactions with noncatalytic sites. Such exosites are regions involved in substrate processing, localized outside the active site, and are potential binding sites of specific MMP inhibitors. Knowledge about regulation of MMP activity is essential for understanding various physiological processes and pathogenesis of diseases, as well as for the development of new MMP targeting drugs.

Matrix metalloproteinases in cytotoxic lymphocytes impact on tumour infiltration and immunomodulation

To efficiently combat solid tumours, endogenously or adoptively transferred cytotoxic T cells and natural killer (NK) cells, need to leave the vasculature, traverse the interstitium and ultimately infiltrate the tumour mass. During this locomotion and migration in the three dimensional environment many obstacles need to be overcome, one of which is the possible impediment of the extracellular matrix. The first and obvious one is the sub-endothelial basement membrane but the infiltrating cells will also meet other, both loose and tight, matrix structures that need to be overridden. Matrix metalloproteinases (MMPs) are believed to be one of the most important endoprotease families, with more than 25 members, which together have function on all known matrix components. This review summarizes what is known on synthesis, expression patterns and regulation of MMPs in cytotoxic lymphocytes and their possible role in the process of tumour infiltration. We also discuss different functions of MMPs as well as the possible use of other lymphocyte proteases for matrix degradation.

Silencing heat shock protein 27 decreases metastatic behavior of human head and neck squamous cell cancer cells in vitro

The small heat shock protein 27 (Hsp27) is a molecular chaperone that is involved in a variety of cellular functions in cancer cells. The purpose of this research is to study Hsp27 in vitro metastatic behaviors of head and neck squamous cell carcinoma cells (HNSCC). The expression of Hsp27 in primary and metastatic cell lines derived from the primary HNSCC and a synchronous lymph node metastasis in the same patient was determined using real-time PCR and Western blotting. Proliferation of the primary and metastatic HNSCC cell lines was evaluated using the MTS proliferation assay. Metastatic behavior was assessed using migration and invasion assays. SiRNA knockdown of Hsp27 was performed in the highly migratory metastatic HNSCC cell line. MTS assays showed that the primary (UM-SCC-22A) and metastatic (UM-SCC-22B) HNSCC have similar proliferation rates. However, UM-SCC-22B derived from the metastasis showed 2.3- to 3.6-fold higher migration ability and 2-fold higher invasion ability than UM-SCC-22A. Real-time PCR demonstrated that Hsp27 mRNA is 22.4-fold higher in metastatic UM-SCC-22B than primary UM-SCC-22A. Similarly, Western blotting showed that Hsp27 is rarely detectable in UM-SCC-22A whereas UM-SCC-22B expresses a 25-fold higher level of Hsp27 protein. SiRNA-mediated knockdown of Hsp27 in UM-SCC-22B reduced Hsp27 mRNA expression by nearly 6-fold and protein expression by 23-fold. Furthermore, siRNA knockdown of Hsp27 decreased metastatic behaviors of UM-SCC-22B by 3- to 4-fold in migration and 2-fold in cell invasion reducing cell invasion and migration to levels similar to the primary HNSCC UM-SCC-22A. These data indicate that Hsp27 may regulate metastatic potential of HNSCC cancer cells. Targeting Hsp27 may decrease metastasis in head and neck squamous cell cancer cells.

Lewis (y) antigen overexpression increases the expression of MMP-2 and MMP-9 and invasion of human ovarian cancer cells

Lewis (y) antigen is a difucosylated oligosaccharide present on the plasma membrane, and its overexpression is frequently found in human cancers and has been shown to be associated with poor prognosis. Our previous studies have shown that Lewis (y) antigen plays a positive role in the process of invasion and metastasis of ovarian cancer cells. However, the mechanisms by which Lewis (y) antigen enhances the invasion and tumor metastasis are still unknown. In this study, we established a stable cell line constitutively expressing Lewis (y) antigen (RMG-1-hFUT) by transfecting the cDNA encoding part of the human α1,2-fucosyltransferase (α1,2-FUT) gene into the ovarian cancer cell line RMG-1, and investigated whether Lewis (y) antigen regulates the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9, and tissue inhibitors of metalloproteinases (TIMP-1) and TIMP-2. We found that RMG-1-hFUT cells exhibited higher invasive capacities than their control cells. In addition, expression of TIMP-1 and TIMP-2 was down-regulated and expression of MMP-2 and MMP-9 was up-regulated. Anti-Lewis (y) antigen antibody treatment significantly reversed the expression of TIMP-1, TIMP-2, MMP-2 and MMP-9. Taken together, we provide the first evidence that down-regulation of TIMP-1 and TIMP-2 and up-regulation of MMP-2 and MMP-9 represents one of the mechanisms by which Lewis (y) antigen promotes cell invasion.

Effects of IL-2 on MMP expression in freshly isolated human NK cells and the IL-2-independent NK cell line YT

Interleukin-2 is an important activation factor for natural killer (NK) cells but its effect on NK cell matrix metalloproteinases (MMP) production and matrix degradation is less well investigated. We have used freshly isolated human NK cells and the IL-2-independent NK cell line, YT, to investigate the effects of IL-2 stimulation on NK cell invasion of Matrigel and on MMP expression and production. In YT cells, we found opposing early and late effects of IL-2 stimulation with an early (2 h) increase in MMP-9 protein level and enhanced migration in the Matrigel invasion assay and by 30 hours a decreased mRNA expression of MMP-2, MMP-9, MMP-13, MT3-MMP, and MT6-MMP. We also found a preculture period of 48 hours with IL-2 to negatively affect YT cell migration. We furthermore found that freshly isolated human NK cells Matrigel invasion was MMP-dependent and it increased in response to IL-2. Importantly, in freshly isolated human NK cells we did not see a downregulation of MMPs after 24 hours IL-2 stimulation, but instead a significant upregulation of MT6-MMP mRNA. Because of the cellular localisation of MT6-MMP, which ensures a focalized proteolytic activity, and its high expression compared with the other MMPs in freshly isolated human NK cells makes it of interest to study further.

Accelerated wound repair in ADAM-9 knockout animals

ADAM-9 belongs to a family of transmembrane, disintegrin-containing metalloproteinases (ADAMs) involved in protein ectodomain shedding and cell-cell and cell-matrix interactions. Although the functions of many ADAM family members are known, the specific biological function of ADAM-9 is still unclear. In this study, we have analyzed ADAM-9 temporal and spatial distribution during wound healing. We showed increased ADAM-9 transcript expression during the first 7 days post-wounding and, by immunolocalization, detected ADAM-9 in all migrating and proliferating keratinocytes from days 3 to 7. In older 14-day-old wounds, ADAM-9 expression was restored. We have investigated the role of this protein in the healing process following excisional wounding. Animals deficient in ADAM-9 showed accelerated wound repair compared with control littermates. No alterations in neutrophil, leukocyte, and macrophage infiltration were observed. However, re-epithelialization was significantly faster in Adam-9 -/- than control wounds. Although no differences in proliferation were observed in vivo and in vitro, increased migration of keratinocytes was responsible for this effect. These results show the previously unreported role of ADAM-9 in wound repair by regulating keratinocyte migration through modulation of collagen XVII shedding.

Role of chemokines in the biology of natural killer cells

Natural killer (NK) cells represent a major subpopulation of lymphocytes. These cells have effector functions as they recognize and kill transformed cells as well as microbially infected cells. In addition, alloreactive NK cells have been successfully used to treat patients with acute myeloid leukemia and other hematological malignancies. NK cells are also endowed with immunoregulatory functions since they secrete cytokines such as IFN-γ, which favor the development of T helper 1 (Th1) cells, and chemokines such as CCL3/MIP-1α and CCL4/MIP-1β, which recruit various inflammatory cells into sites of inflammation. In human blood, NK cells are divided into CD56(bright) CD16(dim) and CD56(dim) CD16(bright) subsets. These subsets have different phenotypic expression and may have different functions; the former subset is more immunoregulatory and the latter is more cytolytic. The CD56(bright)CD16(dim) NK cells home into tissues such as the peripheral lymph nodes (LNs) under physiological conditions because they express the LN homing receptor CCR7 and they respond to CCL19/MIP-3β and CCL21/SLC chemokines. They also distribute into adenoid tissues or decidual uterus following the CXCR3/CXCL10 or CXCR4/CXCL12 axis. On the other hand, both NK cell subsets migrate into inflammatory sites, with more CD56(dim)CD16(bright) NK cells distributing into inflamed liver and lungs. CCR5/CCL5 axis plays an important role in the accumulation of NK cells in virally infected sites as well as during parasitic infections. CD56(bright)CD16(dim) cells also migrate into autoimmune sites such as inflamed synovial fluids in patients having rheumatoid arthritis facilitated by the CCR5/CCL3/CCL4/CCL5 axis, whereas they distribute into inflamed brains aided by the CX₃CR1/CX₃CL1 axis. On the other hand, CD56(dim)CD16(bright) NK cells accumulate in the liver of patients with primary biliary disease aided by the CXCR1/CXCL8 axis. However, the types of chemokines that contribute to their accumulation in target organs during graft vs. host (GvH) disease are not known. Further, chemokines activate NK cells to become highly cytolytic cells known as CC chemokine-activated killer (CHAK) cells that kill tumor cells. In summary, chemokines whether secreted in an autocrine or paracrine fashion regulate various biological functions of NK cells. Depending on the tissue and the chemokine secreted, NK cells may ameliorate the disease such as their roles in combating tumors or virally infected cells, and their therapeutic potentials in treating leukemias and other hematological malignancies, as well as reducing the incidence of GvH disease. In contrast, they may exacerbate the disease by damaging the affected tissues through direct cytotoxicity or by the release of multiple inflammatory cytokines and chemokines. Examples are their deleterious roles in autoimmune diseases such as rheumatoid arthritis and primary biliary cirrhosis.

Stromal expression of MMP-13 is required for melanoma invasion and metastasis

Tumor invasion and metastasis of malignant melanoma have been shown to require proteolytic degradation of the extracellular environment achieved primarily by enzymes of the matrix metalloproteinases (MMP) family. We have earlier shown that increased enzyme activity is localized at the border of tumor cells and the adjacent peritumoral connective tissue, emphasizing the importance of tumor-stroma interactions in the regulation of MMP activity. To confirm the role of stroma-derived MMP-13 in the invasion process, we investigated the invasiveness of melanoma cells upon intradermal injection in mice with complete inactivation of MMP-13. Tumor growth was significantly impaired in mmp-13(-/-) mice and most significant at early time points as compared with wild-type littermates. Moreover, metastasis to various organs was reduced to 17.6 vs 30% in lungs, 2.9 vs 30% in the liver. Strikingly, ablation of MMP-13 completely abrogated formation of metastasis in the heart (0 vs 40%). Notably, decreased tumor growth in mmp-13(-/-) mice was associated with reduced blood vessel density. In addition, decreased blood vessel permeability in the tumors was measured by magnetic resonance imaging of tumor-bearing animals. These data suggest an important role of MMP-13 in tumor growth and an unexpected role in organ-specific metastasis of melanoma cells.

Human NK cell lines migrate differentially in vitro related to matrix interaction and MMP expression

Matrix metalloproteinases (MMPs) are thought to be of importance for the migratory ability of natural killer (NK) cells. Their expression and production may influence the amount of tumour-infiltrating NK cells and thereby any therapeutic capability. In this study, we sought to investigate the importance of MMPs for human NK cells' ability to degrade and migrate through the extracellular matrix (ECM). The two human NK cell lines, NK-92 and YT, migratory ability, MMP expression and production as well as their morphological appearance when cultured in the ECM equivalent Matrigel were analysed and compared. The quantitatively more migratory NK-92 cells were found to express invadopodia/podosomes at a significantly higher degree when cultured in Matrigel and gave rise to a general disintegration of the Matrigel. The NK-92 cells had a higher mRNA expression of MMP-2, -9, -13, MT1-, MT3- and MT6-MMP and a significantly higher production of MMP-9 compared to YT cells. These differences could explain the substantial functional difference observed between the two cell lines with respect to migratory capacity. In addition, the number of Matrigel invading NK-92 cells decreased significantly in the presence of the MMP inhibitor GM6001, demonstrating that MMPs have a critical function in their migration.

Natural killer cell-directed therapies: moving from unexpected results to successful strategies

Natural killer (NK) cells influence innate and adaptive immune host defenses. Existing data indicate that manipulating the balance between inhibitory and activating NK receptor signals, the sensitivity of target cells to NK cell-mediated apoptosis, and NK cell cross-talk with dendritic cells might hold therapeutic promise. Efforts to modulate NK cell trafficking into inflamed tissues and/or lymph nodes, and to counteract NK cell suppressors, might also prove fruitful in the clinic. However, deeper investigation into the benefits of combination therapy, greater understanding of the functional distinctions between NK cell subsets, and design of new tools to monitor NK cell activity are needed to strengthen our ability to harness the power of NK cells for therapeutic aims.

Treg depletion-enhanced IL-2 treatment facilitates therapy of established tumors using systemically delivered oncolytic virus

There are several roadblocks that hinder systemic delivery of oncolytic viruses to the sites of metastatic disease. These include the tumor vasculature, which provides a physical barrier to tumor-specific virus extravasation. Although interleukin-2 (IL-2) has been used in antitumor therapy, it is associated with endothelial cell injury, leading to vascular leak syndrome (VLS). Here, we demonstrate that IL-2-mediated VLS, accentuated by depletion of regulatory T cells (Treg), facilitates localization of intravenously (i.v.) delivered oncolytic virus into established tumors in immune-competent mice. IL-2, in association with Treg depletion, generates "hyperactivated" natural killer (NK) cells, possessing antitumor activity and secreting factors that facilitate virus spread/replication throughout the tumor by disrupting the tumor architecture. As a result, the combination of Treg depletion/IL-2 and systemic oncolytic virotherapy was found to be significantly more therapeutic against established disease than either treatment alone. These data demonstrate that it is possible to combine biological therapy with oncolytic virotherapy to generate systemic therapy against established tumors.

Differential locomotion of long- and short-term IL-2-activated murine natural killer cells in a model matrix environment

Tumour infiltration by activated natural killer (A-NK) cells is a pre-requisite for tumour eradication by adoptive NK cell transfer. Extravasated A-NK cells do not always succeed in reaching the crucial target cell conjugation. Therefore, we wished to study A-NK cell locomotion and interactions with melanoma cells in a matrix environment (Matrigel) by electron, confocal and fluorescence microscopy. Two distinct patterns of A-NK cell-mediated matrix disintegration were revealed during incubation of tumour cells and A-NK cells in Matrigel: (1) A-NK cells pre-cultured for 5 days altered the homogeneous texture of the Matrigel, an initial microporous appearance became a loose filamentous meshwork by 24 h. Matrix degrading protease inhibitors could not fully prevent this, but could delay the process; and (2) A-NK cells pre-cultured for 6 days or more, instead formed large excavations in the Matrigel leaving the remaining matrix less affected compared to the effects by the younger A-NK cells. By histochemical staining with Cupromeronic Blue, the excavations were shown to contain proteoglycan material. Protease inhibitors had no discernable effect on the development of the excavations. The conspicuous capacity of A-NK cells to disintegrate extracellular matrix and the formation of large excavations seems only partially to depend on matrix-degrading proteases. Formation of extracellular proteoglycan material is suggested to facilitate A-NK cell locomotion within a matrix environment.

Role of ADAM-9 disintegrin-cysteine-rich domains in human keratinocyte migration

ADAM-9 belongs to a family of transmembrane, disintegrin-containing metalloproteinases involved in protein ectodomain shedding and cell-cell and cell-matrix interactions. The aim of this study was to analyze the expression of ADAM-9 in skin and to assess the role of this proteolytic/adhesive protein in skin physiology. In normal skin, ADAM-9 expression was detected in both the epidermis and dermis and in vitro in keratinocytes and fibroblasts. Here we report that ADAM-9 functions as a cell adhesion molecule via its disintegrin-cysteine-rich domain. Using solid phase binding assays and antibody inhibition experiments, we demonstrated that the recombinant disintegrin-cysteine-rich domain of ADAM-9 specifically interacts with the beta1 integrin subunit on keratinocytes. This was corroborated by co-immunoprecipitation. In addition, engagement of integrin receptors by the disintegrin-cysteine-rich domain resulted in ERK phosphorylation and increased MMP-9 synthesis. Treatment with the ERK inhibitor PD98059 inhibited MMP-9 induction. Furthermore, the presence of the soluble disintegrin-cysteine-rich domain did not interfere with cell migration on different substrates. However, keratinocytes adhering to the immobilized disintegrin-cysteine-rich domain showed increased motility, which was partially due to the induction of MMP-9 secretion. In summary, our results indicate that the ADAM-9 adhesive domain plays a role in regulating the motility of cells by interaction with beta1 integrins and modulates MMP synthesis.

Influence of conjugated linoleic acid isomers on the metastasis of colon cancer cells in vitro and in vivo

This study investigated the isomer-specific effects of cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) conjugated linoleic acid (CLA) on the metastasis of colon cancer cells in vitro and in vivo. Cell migration was examined by a Boyden chamber assay in SW480 cells. MMP-9 activity was monitored by gelatin zymography, and MMP-9 protein and mRNA levels were determined by Western blot and RT-PCR analysis, respectively, in SW480 cells. For the experimental metastasis, BALB/c mice were injected intravenously with CT-26 cells in the tail vein. Mice were fed a diet containing either no CLA or 0.1% c9,t11 or t10,c12 CLA for 4 weeks. In experimental metastasis, the numbers of pulmonary nodules were significantly lower in mice fed CLA isomers than in mice fed a control diet (P<.05). Results from the Boyden chamber assay revealed that c9,t11 CLA significantly inhibited cell migration (P<.05), whereas t10,c12 CLA had no effect on cell migration. The activity of MMP-9 was significantly inhibited by c9,t11 CLA (P<.05) but not by t10,c12 CLA. However, neither MMP-9 protein nor mRNA levels were altered by either of these CLA isomers. We have demonstrated that diets containing 0.1% c9,t11 and t10,c12 CLA were equally effective in inhibiting colon cancer cell metastasis in vivo. However, in vitro, only c9,t11 but not t10,c12 inhibited colon cancer cell migration and MMP-9 activity.

Decidual NK cells alter in vitro first trimester extravillous cytotrophoblast migration: a role for IFN-gamma

Abnormal placentation results in either inadequate (consequences: recurrent miscarriage, intrauterine growth restriction, and preeclampsia) or overzealous (consequences: placenta accreta, increta, and percreta) placentation. NK cells dominate in first trimester decidua and probably control extravillous cytotrophoblast (EVT) invasion. We examined this interaction in a novel way, using NK cells and villous explants from concordant first trimester pregnancies cocultured using a new collagen (two-dimensional) model of placentation. Decidual NK (dNK) cells exerted contact-independent inhibition of normal cytotrophoblast migration, associated with changes in the cytotrophoblast expression of metalloproteases-2 and -9, and plasminogen activator inhibitor-1. dNK cells did not affect EVT proliferation and apoptosis, and cell column formation. dNK cell effects were partially reversed by neutralizing Abs against IFN-gamma. We provide ex vivo human evidence of a direct role for dNK in modulating EVT differentiation as they form columns and then migrate from anchoring villi.

Mapping of quantitative trait loci determining NK cell-mediated resistance to MHC class I-deficient bone marrow grafts in perforin-deficient mice

NK cells reject allogeneic and MHC class I-deficient bone marrow (BM) grafts in vivo. The mechanisms used by NK cells to mediate this rejection are not yet thoroughly characterized. Although perforin plays a major role, perforin-independent mechanisms are involved as well. C57BL/6 mice deficient in perforin (B6 perforin knockout (PKO)) reject class I-deficient TAP-1 KO BM cells as efficiently as normal B6 mice. In contrast, perforin-deficient 129S6/SvEvTac mice (129 PKO) cannot mediate this rejection while normal 129 mice efficiently reject. This suggests that in 129, but not in B6, mice, perforin is crucial for NK cell-mediated rejection of MHC class I-deficient BM grafts. To identify loci linked to BM rejection in perforin-deficient mice, we generated backcross 1 progeny by crossing (129 x B6)F(1) PKO mice to 129 PKO mice. In transplantation experiments, >350 backcross 1 progeny were analyzed and displayed a great variation in ability to reject TAP-1 KO BM grafts. PCR-based microsatellite mapping identified four quantitative trait loci (QTL) on chromosomes 2, 4, and 8, with the QTL on chromosome 8 showing the highest significance, as well as a fifth epistatic QTL on chromosome 3. This study describes the first important step toward identifying BM graft resistance gene(s).

Analyses and perspectives in cancer immunotherapy

Since the last two decades, rapid progress has been made in the field of cancer immunotherapy relevant to manipulation of adaptative cytotoxic T lymphocytes (CTLs) and innate immunity natural killer (NK) cells as well as antibodies. Many possibilities are now offered for therapeutic purposes contributing to better approaches in treatment of cancer.

Matrix metalloproteinase-1 produced by human CXCL12-stimulated natural killer cells

Natural killer (NK) cells play a key role in inflammation and tumor regression through their ability to migrate into tissues. CXCL12 is a chemokine that promotes lymphocyte invasion and migration into tissues; however, the mechanism for this process remains incompletely understood. In this study, we show that CXCL12 significantly enhanced CD16(+)CD56(+) human peripheral NK-cell invasion into type I collagen by the catalytic activity of matrix metalloproteinase-1 (MMP-1). Confocal immunofluorescence and co-immunoprecipitation studies suggest that MMP-1 colocalized with alpha(2)beta(1) integrin on CXCL-12-stimulated NK-cell surface. The binding of pro-MMP-1 with alpha(2)beta(1) integrin required activation of G(i)-coupled pathway. However, the production of MMP-1 from CXCL12-stimulated NK cells was mediated by p38 and mitogen-activated or extracellular signal-regulation protein kinase kinase 1/2 in a manner independent of the G(i)-coupled pathway. These results suggest that CXCL12/CXCR4 interaction transduces the two signaling pathways to promote NK-cell invasion, which stimulates pericellular degradation of extracellular matrix proteins by membrane-associated MMP-1. The mechanisms would thus play a role in facilitating lymphocyte trafficking and accumulation in tissues during physiological and pathological processes.

Tumor metastasis in an orthotopic murine model of head and neck cancer: Possible role of TGF-beta 1 secreted by the tumor cells

In an orthotopic murine model of head and neck cancer, combined subcutaneous and intratumoral vaccination with recombinant vaccinia virus expressing interleukin-2 (rvv-IL-2) induced significant tumor regression early on therapy. However, its efficacy was restricted by recurrent tumor growth and loco-regional metastases. In this study, we explored the mechanism of tumor metastasis. We compared the levels of expression of a number of molecules involved in tumor metastasis, which included transforming growth factor-beta1 (TGF-beta1), E-cadherin, matrix metalloproteinases (MMPs): MT1-MMP, MMP-2, MMP-9, their tissue inhibitors (TIMPs): TIMP-1/TIMP-2, and pro-angiogenic factors CD31, VEGF-R2, and iNOS between primary and metastatic tumors by real-time RT-PCR and immunohistochemistry. We detected spontaneous lymph node and tongue metastasis. Metastasis was delayed in rvv-IL-2 treated mice. Cultured tumor cells expressed negligible amount of TGF-beta1. Untreated or metastatic tumors, on the other hand, expressed high levels of TGF-beta1 and secreted TGF-beta1 in the sera of tumor-bearing mice. Levels of TGF-beta1 in the sera suddenly jumped at the time when tumor metastasis started. In the metastatic tumors, levels of MT1-MMP, MMP-2, and MMP-9 were significantly elevated (P < 0.001), while levels of TIMP-1/TIMP-2 and E-cadherin were decreased (P < 0.001) compared to control or primary tumors. Levels of CD31, VEGF-R2, and iNOS were also significantly elevated in the metastatic lesions (P < 0.001). The concurrence of high levels of TGF-beta1 in the sera, expression of proteins involved in metastasis and initiation of metastasis suggested possible role of TGF-beta1 in on setting the metastatic cascade in this model.

Immunity, Inflammation and Infection in Post-partum Breast and Formula Feeders

PROBLEM

Little is known about immunological recovery in post-partum women and if lactational status affects immunocompetence. Many physiological changes occur, such as uterine involution and recovery of non-pregnant immune status. These changes may also affect susceptibility to disease.

METHOD

The study compared immune and inflammatory activation markers (serum cytokines, Epstein Barr viral antibody titer, neopterin, c-reactive protein (CRP), lymphocyte subset percentages, ex vivo cytokine production, lymphocyte proliferation, salivary Immunoglubulin A (sIgA) in exclusively breastfeeding (EB) and exclusively formula feeding (EF) women at 4-6 weeks post-partum, and control (C) women.

RESULTS

EBs had higher ratios of interferon-gamma (IFN-gamma)/interleukin-10 (IL-10) than EFs, and post-partums were higher than Cs. Both IFN-gamma and IL-10 were significantly higher in post-partums compared to controls. Post-partums also had higher proinflammatory cytokines, CRP and neopterin, salivary IgA and fewer infection symptoms. There were also differences in lymphocyte subsets.

CONCLUSIONS

The post-partum period is oriented towards heightened and activated innate and specific immune defenses, with breastfeeding providing a boost in these phenomena.

Alpha3beta1 integrin regulates MMP-9 mRNA stability in immortalized keratinocytes: a novel mechanism of integrin-mediated MMP gene expression

Matrix metalloproteinases facilitate cell migration and tumor invasion through their ability to proteolyse the extracellular matrix. The laminin-binding integrin alpha3beta1 is expressed at high levels in squamous cell carcinomas and in normal keratinocytes during cutaneous wound healing. We showed previously that alpha3beta1 is required for MMP-9/gelatinase B secretion in immortalized mouse keratinocytes (MK cells) and that this regulation was acquired as part of the immortalized phenotype, suggesting a possible role for alpha3beta1 during malignant conversion. In the current study, we identify a novel mechanism whereby alpha3beta1 regulates the induction of MMP-9 expression that occurs in response to activation of a MAPK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway. Inhibition of MEK/ERK signaling in wild-type MK cells with a pharmacological inhibitor, U0126, showed that ERK activation was necessary for high levels of endogenous MMP-9 gene expression and activity of a transfected MMP-9 promoter. Furthermore, activation of MEK/ERK signaling in these cells with an oncogenic mutant of Ras, RasV12, increased both endogenous MMP-9 gene expression and MMP-9 promoter activity. Experiments with alpha3beta1-deficient MK cells revealed that alpha3beta1 was required for both baseline levels and RasV12-induced levels of MMP-9 mRNA expression. However, alpha3beta1 was not required for RasV12-mediated activation of ERK or for ERK-dependent MMP-9 promoter activity. Direct comparison of mRNA turnover in the wild type and alpha3-null MK cells identified a requirement for alpha3beta1 in stabilization of MMP-9 mRNA transcripts. These results identify a novel function for integrins in promoting mRNA stability as a mechanism to potentiate MAPK-mediated gene expression. They also suggest a role for alpha3beta1 in maintaining high levels of MMP-9 mRNA expression in response to oncogenic activation of MEK/ERK signaling pathways.

Impact of FASL-induced apoptosis in the elimination of tumor cells by NK cells

The cytotoxic effector functions of NK cells are important for enabling the immune system to cope efficiently with infection and malignancy. Two major mechanisms of cytotoxicity are perforin/granzyme- and death receptor-mediated (e.g., FASL- or TRAIL-mediated) induction of cell death. Many studies, including studies in perforin-deficient animals, have led to the conclusion that perforin/granzyme-mediated induction of cell death is a principal pathway used by NK cells to eliminate virus-infected or transformed cells. However, death receptor-mediated apoptosis may also contribute to NK cell-mediated cytotoxicity, as revealed by more recent reports. In the present paper, we have reviewed current data on death receptor-mediated tumor cell apoptosis by NK cells with a particular emphasis on the role of NK cell FASL in the RMA/RMA-S tumor model.

The role of IL-18 in the modulation of matrix metalloproteinases and migration of human natural killer (NK) cells

In this study, we examined whether interleukin-18 (IL-18) affects natural killer (NK) cells' migration and matrix metalloproteinases (MMPs) production. We demonstrated that chemotaxis of human NK cells through basement membrane-like Matrigel was augmented by IL-18. As well, IL-18 stimulation induces the production of activated forms of matrix metalloproteinase-2 (MMP-2) as well as the production of pro-MMP-2 from NK cells. We also demonstrated that MT1-MMP expression on human NK cells, which is a major activator of MMP-2, was induced by IL-18 stimulation coordinated with MMP-2 activation. These data suggest that the MT1-MMP/MMP-2 system participates in the degradation of basement membrane components and thus contributes to NK cell migration.

NK cells and the tumour microenvironment: implications for NK-cell function and anti-tumour activity

Although it is clear that natural killer (NK) cells have the ability to recognize and kill tumour cells in vitro, their potential as a highly effective treatment for tumours has not yet been realized in the clinical setting. Following activation, endogenous and adoptively transferred NK cells can be found in tumours. However, not all tumours are equally well-infiltrated, and many of the infiltrating cells do not make target-cell contact but rather reside in the tumour stroma. New insights into the migration of NK cells, their activation status and production of matrix-degrading proteases might help to overcome this localization defect, with implications for the treatment of human cancer.

IL-4 enhances antitumor effect of IL-2 induced A-NK Cells on human colon carcinoma

AIM

Using IL-4 combined with IL-2 to induce A-NK cells and to evaluate the cytotoxicity of A-NK cells and its inhibiting effect on colon tumor growth.

METHODS

The A-NK cells were activated with recombinant lymphokine IL-2 combined IL-4, the cytotoxicity of the effector cells was determined by LDH-L release assay. Its antitumor effect was investigated through growth inhibiting of human colon carcinoma cells in nude mice.

RESULTS

IL-2 alone or combined with IL-4 could induce the activity of A-NK cells successively which could kill K562, Anip973 and CC95 tumor cells in vitro by LDH-L release assay (39.00 ± 9.16 vs 77.68 ± 12.80, 43.10 ± 10.05 vs 80.02 ± 13.74, 42.14 ±9.72 vs 79.10 ±12.65, P <0.01) and inhibit the growth of human colon carcinoma cells in nude mice (1.04 ± 0.15 vs 0.62 ± 0.16, P <0.01).The results suggested that there was expression of IL-4 receptor on the surface of A-NK cells.

CONCLUSION

IL-4 can enhance the antitumor activity of IL-2 induced A-NK cells. The method may have some potential application value in human cancer treatment.

Inhibitory effects of c9,t11-conjugated linoleic acid on invasion of human gastric carcinoma cell line SGC-7901

AIM: To investigate the effect of c9,t11-conjugated linoleic acid (c9,t11-CLA) on the invasion of human gastric carcinoma cell line and its possible mechanism of preventing metastasis.

METHODS: Using reconstituted basement membrane invasion, chemotaxis, adhesion, PAGE substrate zymography and RT-PCR assays, we analyzed the abilities of invasion, direct migration, adhesion of intracellular matrix, as well as the activity of type IV collagenase and expression of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 mRNA in SGC-7901 cells which were treated with gradually increased concentrations (25, 50, 100 and 200 μmol/L) of c9,t11-CLA for 24 h.

RESULTS: At the concentrations of 200 μmol/L, 100 μmol/L and 50 μmol/L, c9,t11-CLA suppressed the invasion of SGC-7901 cells into the reconstituted basement membrane by 53.7%, 40.9% and 29.3%, respectively, in comparison with the negative control. Only in the 200 μmol/L c9,t11-CLA group, the chemotaxis of SGC-7901 cells was inhibited by 16.0% in comparision with the negative control. C9,t11-CLA also could inhibit the adhesion of SGC-7901 cells to laminin, fibronectin and Matrigel, increase the expression of TIMP-1 and TIMP-2 mRNA, and reduce type IV collagenase activities in the serum-free medium supernatant of SGC-7901 cells.

CONCLUSION: c9,t11-CLA can inhibit the invasion of SGC-7901 cells at multiple procedures in tumor metastasis cascade, which may be associated with the induction of TIMP-1 and TIMP-2 mRNA expression.

A site on laminin alpha 5, AQARSAASKVKVSMKF, induces inflammatory cell production of matrix metalloproteinase-9 and chemotaxis

Several peptide sequences in laminin alpha1, the alpha-chain of laminin (Ln)-1, mediate biological responses in vitro, but Ln-1 is rare in vivo. Since Ln-5 and Ln-10, which contain the alpha3 and alpha5 chains, respectively, are the most prominent laminin heterotrimers in normal adult tissues and few functional domains in other laminin chains have been identified, we are investigating the alpha3 and alpha5 chains for biological activities. Incubation of mouse macrophages with the laminin alpha5 peptide AQARSAASKVKVSMKF resulted in marked increase in matrix metalloproteinase (MMP)-9 mRNA and gelatinolytic activity in the conditioned media, whereas the corresponding alpha3 peptide QQARDAANKVAIPMRF had no effect. AQARSAASKVKVSMKF also induced expression of MMP-14, while MMP-2, MMP-3, MMP-7, MMP-12, and MMP-13 were not induced by this peptide. Deletion analyses indicated that a minimal sequence of ASKVKVSMKF was sufficient for increasing MMP-9 expression. AQARSAASKVKVSMKF was also chemotactic for neutrophils and macrophages in vitro, and induced accumulation of neutrophils and macrophages in lung airspaces in vivo following intranasal instillation into mice. Comparable accumulation occurred in MMP-9-deficient mice, indicating that MMP-9 was not required for AQARSAASKVKVSMKF-induced inflammatory cell emigration in the lung. A scrambled version of the minimal peptide, KAKSFVMVSK, was inactive. These data indicate that laminin alpha5-derived peptides can induce inflammatory cell chemotaxis and metalloproteinase activity.

The interplay of collagen IV, tumor necrosis factor-alpha, gelatinase B (matrix metalloprotease-9), and tissue inhibitor of metalloproteases-1 in the basal lamina regulates Sertoli cell-tight junction dynamics in the rat testis

During spermatogenesis, preleptotene and leptotene spermatocytes must translocate across the blood-testis barrier formed by inter-Sertoli cell-tight junctions (TJs) from the basal compartment of the seminiferous epithelium adjacent to the basement membrane to the adluminal compartment at stages VIII-IX for further development. Because of the close proximity between extracellular matrix (ECM) that constitutes the basement membrane and the blood-testis barrier, we sought to investigate the role of ECM in Sertoli cell TJ dynamics. When Sertoli cells were cultured in vitro to initiate the assembly of the Sertoli cell TJ-permeability barrier, the presence of an anticollagen IV antibody indeed perturbed the barrier. Because ECM is known to maintain a pool of cytokines and TNFalpha has been shown to regulate TJ dynamics in other epithelia, we investigated whether TNFalpha can regulate Sertoli cell TJ function via its effects on collagen alpha3(IV) and other proteins that maintain the homeostasis of ECM. As expected, recombinant TNFalpha perturbed the Sertoli cell TJ-barrier assembly in vitro dose dependently. TNFalpha also inhibited the timely induction of occludin, which is known to associate with the Sertoli cell TJ-barrier assembly. Furthermore, TNFalpha induced the expression of Sertoli cell collagen alpha3(IV), gelatinase B (matrix metalloprotease-9, MMP-9) and tissue inhibitor of metalloproteases-1 but not gelatinase A (matrix metalloprotease-2), and promoted the activation of pro-MMP-9. These results thus suggest that the activated MMP-9 induced by TNFalpha is used to cleave the existing collagen network in the ECM, thereby perturbing the TJ-barrier. This in turn creates a negative feedback that causes TNFalpha to induce collagen alpha3(IV) and tissue inhibitor of metalloproteases-1 expression so as to replenish the collagen network in the disrupted TJ-barrier and limit the activity of MMP-9. Taken collectively, these observations strengthen the notion that ECM is involved in the regulation of junction dynamics in addition to its structural role in the testis.

MMP9 induction by vascular endothelial growth factor receptor-1 is involved in lung-specific metastasis

The molecular mechanism of tissue-specific metastasis in tumors endogenously expressing members of the vascular endothelial growth factor (VEGF) family is not yet clear. Here we demonstrate that MMP9 is specifically induced in premetastatic lung endothelial cells and macrophages by distant primary tumors via VEGFR-1/Flt-1 tyrosine kinase (TK) and that it significantly promotes lung metastasis. In a genetic approach using mice, suppression of MMP9 induction by deletion of either VEGFR-1TK or MMP9 markedly reduced lung metastasis. Furthermore, the MMP9 levels in endothelial cells of normal lung lobes from patients carrying distant tumors were significantly elevated as compared with those from patients without tumors. Thus, a block of MMP9 induction via VEGFR-1 inhibition could be useful for the prevention of tumor metastasis in lung.

IL-2-mediated upregulation of uPA and uPAR in natural killer cells

Urokinase plasminogen activator (uPA) and its receptor uPAR play a major role in immune cell-mediated, including natural killer (NK) cell-mediated, degradation of extracellular matrices. Herein, we investigate the effects of IL-2 on NK cell uPA and uPAR. RNA and protein analyses showed upregulation of uPA and uPAR following IL-2 stimulation. Gel-shift assays and Western blots detected uPA and uPAR mRNA binding proteins (mRNABPs), previously shown to destabilize uPA and uPAR mRNA. Following IL-2 stimulation, a downregulation of uPAR mRNABP and a reciprocal induction of uPAR mRNA were noted. The increase in uPA following IL-2 stimulation appeared to be more transcriptionally regulated. These data suggest that IL-2 upregulates both uPA and uPAR in NK cells through posttranscriptional as well as transcriptional mechanisms, partially explaining increases in NK cell invasiveness following IL-2 stimulation.

Paracrine regulation of matrix metalloproteinase expression in endometriosis

Following retrograde menstruation, shed endometrial tissue fragments attach to and invade the peritoneal surface to form established endometriotic lesions. With disease progression, the biochemically active lesions undergo remodeling and become fibrotic. Matrix metalloproteinase enzymes (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) play a significant role in normal endometrial remodeling during menses. Anomalous expression of MMPs and TIMPs has been identified in endometriotic lesions as compared to their highly regulated expression in eutopic endometrium. The paracrine mechanisms regulating misexpression of MMPs and TIMPs by endometriotic lesions are, however, not well defined. Misexpression of the MMPs and TIMPs may be due to innate anomalies in the eutopic endometrium from women with endometriosis, in the resident immune cells and peritoneal cells that juxtapose the ectopic endometrium, and/or numerous substances present in peritoneal fluid of women with endometriosis. The majority of MMPs are under strict transcriptional regulation. Steroid hormones and cytokines appear to act on the MMP promoter, either independently or in consort, to provide both positive and negative regulation of these genes. Misregulated expression of MMPs and TIMPs is associated with a more aggressive phenotype and a cascade of events facilitating peritoneal extracellular matrix degradation and establishment or remodeling of endometriotic lesions. The mechanisms by which MMP and TIMP expression are misregulated warrant further investigation as such information may provide insight into novel therapeutic modalities for endometriosis.

Matrix metalloproteinases (MMPs) regulate fibrin-invasive activity via MT1-MMP-dependent and -independent processes

Cross-linked fibrin is deposited in tissues surrounding wounds, inflammatory sites, or tumors and serves not only as a supporting substratum for trafficking cells, but also as a structural barrier to invasion. While the plasminogen activator-plasminogen axis provides cells with a powerful fibrinolytic system, plasminogen-deleted animals use alternate proteolytic processes that allow fibrin invasion to proceed normally. Using fibroblasts recovered from wild-type or gene-deleted mice, invasion of three-dimensional fibrin gels proceeded in a matrix metalloproteinase (MMP)-dependent fashion. Consistent with earlier studies supporting a singular role for the membrane-anchored MMP, MT1-MMP, in fibrin-invasive events, fibroblasts from MT1-MMP-null mice displayed an early defect in invasion. However, MT1-MMP-deleted fibroblasts circumvented this early deficiency and exhibited compensatory fibrin-invasive activity. The MT1-MMP-independent process was sensitive to MMP inhibitors that target membrane-anchored MMPs, and further studies identified MT2-MMP and MT3-MMP, but not MT4-MMP, as alternate pro-invasive factors. Given the widespread distribution of MT1-, 2-, and 3-MMP in normal and neoplastic cells, these data identify a subset of membrane-anchored MMPs that operate in an autonomous fashion to drive fibrin-invasive activity.

Gene therapy of melanoma pulmonary metastasis by intramuscular injection of plasmid DNA encoding tissue inhibitor of metalloproteinases-1

Tumor cell invasion and metastasis are a complex multistep process that involves the degradation of extracellular matrix proteins by matrix metalloproteinases. Tissue inhibitor of metalloproteinase-1 (TIMP-1) acts as a negative regulator of matrix metalloproteinases and thus prevents tumor cell invasion and metastasis by preserving extracellular matrix integrity. In the present study, we investigated whether increasing serum TIMP-1 levels by gene transfer would decrease experimental pulmonary metastasis of melanoma in C57BL/6 mice. Female animals bearing B16F10 melanoma pulmonary metastasis were injected intramuscularly twice per week with 100 microg of plasmid DNA encoding the human TIMP-1 cDNA (TIMP-1pDNA). Substantive levels of serum human TIMP-1 were observed 3 days after single injection and were found for 6 days thereafter. Pulmonary metastasis was significantly reduced in the mice following 4 weeks of TIMP-1 treatment as compared to the controls that were treated with the plasmid DNA vector alone. Further reduction of pulmonary metastasis and increase in survival were realized by intraperitoneal injection of 1000 U of IL-2 twice per week in combination with TIMP-1 treatment. In a parallel in vitro study, a 3-fold increase in TIMP-1 expression was observed in NIH3T3 cells after IL-2 treatment. Therefore, up-regulation of TIMP-1 expression by IL-2 likely contributed to the additive effect of IL-2 and TIMP-1 in reducing metastatic disease in the animal model. In conclusion, our findings support the potential of TIMP-1 gene therapy for the prevention of metastatic melanoma.