Proteolytic and Opportunistic Breaching of the Basement Membrane Zone by Immune Cells during Tumor Initiation

Cancer-related inflammation impacts significantly on cancer development and progression. From early stages, neutrophils and macrophages are drawn to pre-neoplastic cells in the epidermis, but before directly interacting, they must first breach the underlying extracellular matrix barrier layer that includes the basement membrane. Using several different skin cancer models and a collagen I-GFP transgenic zebrafish line, we have undertaken correlative light and electron microscopy (CLEM) to capture the moments when immune cells traverse the basement membrane. We show evidence both for active proteolytic burrowing and for the opportunistic use of pre-existing weak spots in the matrix layer. We show that these small holes, as well as much larger, cancer cell-generated or wound-triggered gaps in the matrix barrier, provide portals for immune cells to access cancer cells in the epidermis and thus are rate limiting in cancer progression.

Immunocytochemical localization of the ectoenzyme aminopeptidase N in the human breast

The ectoenzyme aminopeptidase N (APN) was localized in the normal human breast at both the light microscopic and the ultrastructural level. APN was expressed on intralobular and interlobular fibroblasts and on the apical surface of some luminal epithelial cells. This enzyme was not detected on either myoepithelial cells and their associated basement membrane or capillary endothelium. Furthermore, the staining pattern was maintained in benign and malignant breast disease. APN belongs to a family of enzymes that hydrolyze peptides in the extracellular space. As with other ectoenzymes present in the breast, APN expression is restricted to specific cell types. This pattern of expression may indicate a role for these enzymes in the biology of the normal breast.

Lysyl Hydroxylase 3 Localizes to Epidermal Basement Membrane and Is Reduced in Patients with Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in COL7A1 resulting in reduced or absent type VII collagen, aberrant anchoring fibril formation and subsequent dermal-epidermal fragility. Here, we identify a significant decrease in PLOD3 expression and its encoded protein, the collagen modifying enzyme lysyl hydroxylase 3 (LH3), in RDEB. We show abundant LH3 localising to the basement membrane in normal skin which is severely depleted in RDEB patient skin. We demonstrate expression is in-part regulated by endogenous type VII collagen and that, in agreement with previous studies, even small reductions in LH3 expression lead to significantly less secreted LH3 protein. Exogenous type VII collagen did not alter LH3 expression in cultured RDEB keratinocytes and we show that RDEB patients receiving bone marrow transplantation who demonstrate significant increase in type VII collagen do not show increased levels of LH3 at the basement membrane. Our data report a direct link between LH3 and endogenous type VII collagen expression concluding that reduction of LH3 at the basement membrane in patients with RDEB will likely have significant implications for disease progression and therapeutic intervention.

High-resolution imaging of selenium in kidneys: a localized selenium pool associated with glutathione peroxidase 3

AIM

Recent advances in quantitative methods and sensitive imaging techniques of trace elements provide opportunities to uncover and explain their biological roles. In particular, the distribution of selenium in tissues and cells under both physiological and pathological conditions remains unknown. In this work, we applied high-resolution synchrotron X-ray fluorescence microscopy (XFM) to map selenium distribution in mouse liver and kidney.

RESULTS

Liver showed a uniform selenium distribution that was dependent on selenocysteine tRNA([Ser]Sec) and dietary selenium. In contrast, kidney selenium had both uniformly distributed and highly localized components, the latter visualized as thin circular structures surrounding proximal tubules. Other parts of the kidney, such as glomeruli and distal tubules, only manifested the uniformly distributed selenium pattern that co-localized with sulfur. We found that proximal tubule selenium localized to the basement membrane. It was preserved in Selenoprotein P knockout mice, but was completely eliminated in glutathione peroxidase 3 (GPx3) knockout mice, indicating that this selenium represented GPx3. We further imaged kidneys of another model organism, the naked mole rat, which showed a diminished uniformly distributed selenium pool, but preserved the circular proximal tubule signal.

INNOVATION

We applied XFM to image selenium in mammalian tissues and identified a highly localized pool of this trace element at the basement membrane of kidneys that was associated with GPx3.

CONCLUSION

XFM allowed us to define and explain the tissue topography of selenium in mammalian kidneys at submicron resolution.

Dual targets for mouse mast cell protease-4 in mediating tissue damage in experimental bullous pemphigoid

Mouse mast cell protease-4 (mMCP-4) has been linked to autoimmune and inflammatory diseases, although the exact mechanisms underlying its role in these pathological conditions remain unclear. Here, we have found that mMCP-4 is critical in a mouse model of the autoimmune skin blistering disease bullous pemphigoid (BP). Mice lacking mMCP-4 were resistant to experimental BP. Complement activation, mast cell (MC) degranulation, and the early phase of neutrophil (PMN) recruitment occurred comparably in mMCP-4(-/-) and WT mice. However, without mMCP-4, activation of matrix metalloproteinase (MMP)-9 was impaired in cultured mMCP-4(-/-) MCs and in the skin of pathogenic IgG-injected mMCP-4(-/-) mice. MMP-9 activation was not fully restored by local reconstitution with WT or mMCP-4(-/-) PMNs. Local reconstitution with mMCP-4(+/+) MCs, but not with mMCP-4(-/-) MCs, restored blistering, MMP-9 activation, and PMN recruitment in mMCP-4(-/-) mice. mMCP-4 also degraded the hemidesmosomal transmembrane protein BP180 both in the skin and in vitro. These results demonstrate that mMCP-4 plays two different roles in the pathogenesis of experimental BP, by both activating MMP-9 and by cleaving BP180, leading to injury of the hemidesmosomes and extracellular matrix of the basement membrane zone.

[Effects of salviandic acid B (SA-B) on activity of basement membrane-type collagenase and impact of regulatory factors in rats with cardiac hypertrophy]

OBJECTIVE

To observe the effect of salviandic acid B (SA-B) on MMP-2/9 and TIMP-2 of fibrotic cardiac tissues in rats and explore the action mechanism of SA-B anti-fibrosis of heart.

METHOD

Ventricular remodeling model was induced by abdominal aortic banding (AAB) in rats. Rats were randomly divided into 6 groups: normal, model, SA-B high, SA-B middle, SA-B low and captopril control group. Histological changes of heart were observed with hemotoxylin and eosin (H&E) staining and Sirius red staining. Hydroxyproline (Hyp) content in heart tissue was measured by hydrolysis method. Expression of heart tissue collagen NIV, MMP-2/9 and TIMP-2 were analyzed with Western blot The activities of heart tissue MMP-2 were determined with gelatin zymography substrate degradation method.

RESULT

SA-B treated groups had lower heart inflammation and lower heart Hyp content; decreased Collagen deposit and alleviated cardiac fibrosis. SA-B treated groups obviously decreased the expression of Collagen IV, MMP-2/9 and TIMP-2. The activity of MMP-2 was decreased in treated SA-B treated groups.

CONCLUSION

The mechanism of SA-B action against cardiac fibrosis may be related to down-regulating the expression of TIMP -2 and the activity of MMP-2/9, thus protect the normal basal membrane.

Collagenolytic/gelatinolytic enzymes in corneal wound healing

We have documented changes in expression of collagenolytic/gelatinolytic enzymes of the matrix metalloproteinase family (MMP) in healing or ulcerating corneal wounds of rat or rabbit. Correlation of our findings with specific changes in the extracellular matrix of the repair tissue suggests two different roles for the enzymes, MMP-2 and MMP-9. MMP-2 is expressed in undamaged corneal stroma where it may degrade the occasional collagen molecule that becomes damaged. After corneal wounding, expression of this enzyme is increased and much of it appears in the active form. These changes persist for at least seven months, suggesting that MMP-2 is involved in the prolonged process of collagen remodelling in the stromal repair tissue. MMP-9 is expressed in the epithelial layer of repair tissue with a timing suggesting it might participate in controlling resynthesis of the basement membrane. MMP-9 also appears to be involved in degradation of the epithelial basement membrane that precedes corneal ulceration.

Hypoxia-induced lysyl oxidase is a critical mediator of bone marrow cell recruitment to form the premetastatic niche

Tumor cell metastasis is facilitated by "premetastatic niches" formed in destination organs by invading bone marrow-derived cells (BMDCs). Lysyl oxidase (LOX) is critical for premetastatic niche formation. LOX secreted by hypoxic breast tumor cells accumulates at premetastatic sites, crosslinks collagen IV in the basement membrane, and is essential for CD11b+ myeloid cell recruitment. CD11b+ cells adhere to crosslinked collagen IV and produce matrix metalloproteinase-2, which cleaves collagen, enhancing the invasion and recruitment of BMDCs and metastasizing tumor cells. LOX inhibition prevents CD11b+ cell recruitment and metastatic growth. CD11b+ cells and LOX also colocalize in biopsies of human metastases. Our findings demonstrate a critical role for LOX in premetastatic niche formation and support targeting LOX for the treatment and prevention of metastatic disease.

N-Glycosylation of laminin-332 regulates its biological functions. A novel function of the bisecting GlcNAc

Laminin-332 (Lm332) is a large heterotrimeric glycoprotein that has been identified as a scattering factor, a regulator of cancer invasion as well as a prominent basement membrane component of the skin. Past studies have identified the functional domains of Lm332 and revealed the relationships between its activities and the processing of its subunits. However, there is little information available concerning the effects of N-glycosylation on Lm332 activities. In some cancer cells, an increase of beta1,6-GlcNAc catalyzed by N-acetylglucosaminyltransferase V (GnT-V) is related to the promotion of cancer cell motility. By contrast, bisecting GlcNAc catalyzed by N-acetylglucosaminyltransferase III (GnT-III) suppresses the further processing with branching enzymes, such as GnT-V, and the elongation of N-glycans. To examine the effects of those N-glycosylations to Lm332 on its activities, we purified Lm332s from the conditioned media of GnT-III- and GnT-V-overexpressing MKN45 cells. Lectin blotting and mass spectrometry analyses revealed that N-glycans containing the bisecting GlcNAc and beta1,6-GlcNAc structures were strongly expressed on Lm332 purified from GnT-III-overexpressing (GnT-III-Lm332) and GnT-V-overexpressing (GnT-V-Lm332) cells, respectively. Interestingly, the cell adhesion activity of GnT-III-Lm332 was apparently decreased compared with those of control Lm332 and GnT-V-Lm332. In addition, the introduction of bisecting GlcNAc to Lm332 resulted in a decrease in its cell scattering and migration activities. The weakened activities were most likely derived from the impaired alpha3beta1 integrin clustering and resultant focal adhesion formation. Taken together, our results clearly demonstrate for the first time that N-glycosylation may regulate the biological function of Lm332. This finding could introduce a new therapeutic strategy for cancer.

Altered expression of basement membrane-related molecules in rat brain pericyte, endothelial, and astrocyte cell lines after transforming growth factor-beta1 treatment

The basement membrane at the blood-brain barrier (BBB) plays important roles in maintaining the structure and function of capillary vessels. The BBB is constructed from endothelial cells, astrocytes and pericytes, but their interactions in the formation or maintenance of basement membrane have not been established. Transforming growth factor-beta1 (TGF-beta1) is known to increase fibronectin in brain capillary basement membrane with deposition of beta-amyloid. We previously reported that the mRNA level of alpha-smooth muscle actin in a brain capillary pericyte cell line TR-PCT1 was increased by treatment with TGF-beta1. In this study, expression of mRNAs encoding basement membrane-related molecules in TR-PCT1, a rat endothelial cell line TR-BBB13, and a type 2 astrocyte cell line TR-AST4 was evaluated by RT-PCR. The effects of TGF-beta1 on expression of basement membrane-related genes in these cell lines were also examined. Fibronectin, MMP-9, tPA, TIMP-1, and PAI-l in TR-PCT1 were higher than in TR-BBB13 and TR-AST4. In TR-PCT1 treated with TGF-beta1, collagen type IV, PAI-1, and MMP-9 were increased, and TIMP-2 was reduced. The change in PAI-1 mRNA was faster than those in MMP-9, TIMP-2, collagen type IV mRNAs. These results suggest that pericytes may be key cells in the maintenance of the basement membrane at the BBB.

The serine/threonine kinase dPak is required for polarized assembly of F-actin bundles and apical–basal polarity in the Drosophila follicular epithelium

During epithelial development cells become polarized along their apical-basal axis and some epithelia also exhibit polarity in the plane of the tissue. Mutations in the gene encoding a Drosophila Pak family serine/threonine kinase, dPak, disrupt the follicular epithelium that covers developing egg chambers during oogenesis. The follicular epithelium normally exhibits planar polarized organization of basal F-actin bundles such that they lie perpendicular to the anterior-posterior axis of the egg chamber, and requires contact with the basement membrane for apical-basal polarization. During oogenesis, dPak becomes localized to the basal end of follicle cells and is required for polarized organization of the basal actin cytoskeleton and for epithelial integrity and apical-basal polarity. The receptor protein tyrosine phosphatase Dlar and integrins, all receptors for extracellular matrix proteins, are required for polarization of the basal F-actin bundles, and for correct dPak localization in follicle cells. dpak mutant follicle cells show increased beta(Heavy)-spectrin levels, and we speculate that dPak regulation of beta(Heavy)-spectrin, a known participant in the maintenance of membrane domains, is required for correct apical-basal polarization of the membrane. We propose that dPak mediates communication between the basement membrane and intracellular proteins required for polarization of the basal F-actin and for apical-basal polarity.

Doxycycline inhibits MMPs via modulation of plasminogen activators in focal cerebral ischemia

Tetracyclines inhibit matrix metalloproteinases (MMPs) and reduce infarction volume following cerebral ischemia. In this thesis an involvement of urokinase could be proven. Cerebral ischemia in rats was induced for 3 h followed by 24 h reperfusion (suture model). Each 6 animals received orally either doxycycline or water. Doxycycline treatment began 10 days before ischemia. MMP-2 and MMP-9 were substantially decreased. The possibility of involvement of the endogenous MMP inhibitors in the MMP inhibiting mechanisms was excluded. The plasminogen activator uPA was significantly decreased by doxycycline indicating an MMP inhibiting mechanism including the plasminogen/plasmin system. In the doxycycline group, this resulted in a decreased damage to the cerebral microvessels and less loss of the basal lamina antigen collagen type IV. Hemoglobin extravasation was also significantly reduced. Our results suggest that doxycycline may have a potential use as an anti-ischemic compound since it provides microvascular protection by inhibiting the plasminogen system.

Oxidative stress activates protein tyrosine kinase and matrix metalloproteinases leading to blood-brain barrier dysfunction

The blood-brain barrier (BBB) formed by brain microvascular endothelial cells (BMVEC) regulates the passage of molecules and leukocytes in and out of the brain. Oxidative stress is a major underlying cause of neurodegenerative and neuroinflammatory disorders and BBB injury associated with them. Using human BMVEC grown on porous membranes covered with basement membrane (BM) matrix (BBB models), we demonstrated that reactive oxygen species (ROS) augmented permeability and monocyte migration across BBB. ROS activated matrix metalloproteinases (MMP-1, -2, and -9) and decreased tissue inhibitors of MMPs (TIMP-1 and -2) in a protein tyrosine kinase (PTK)-dependent manner. Increase in MMPs and PTK activities paralleled degradation of BM protein and enhanced tyrosine phosphorylation of tight junction (TJ) protein. These effects and enhanced permeability/monocyte migration were prevented by inhibitors of MMPs, PTKs, or antioxidant suggesting that oxidative stress caused BBB injury via degradation of BM protein by activated MMPs and by PTK-mediated TJ protein phosphorylation. These findings point to new therapeutic interventions ameliorating BBB dysfunction in neurological disorders such as stroke or neuroinflammation.

Peripheral thermal injury causes blood–brain barrier dysfunction and matrix metalloproteinase (MMP) expression in rat

Mortality after serious systemic thermal injury may be linked to significant increases in cerebral vascular permeability and edema due to blood-brain barrier (BBB) breakdown. This BBB disruption is thought to be mediated by a family of proteolytic enzymes known as matrix metalloproteinases (MMPs). The gelatinases, MMP-2 and MMP-9, digest the endothelial basal lamina of the BBB, which is essential for maintaining BBB integrity. The current study investigated whether disruption of microvascular integrity in a rat thermal injury model is associated with gelatinase expression and activity. Seventy-two adult Sprague-Dawley rats were anesthetized and submerged horizontally, in the supine position, in 100 degrees C (37 degrees C for controls) water for 6 s producing a third-degree burn affecting 60-70% of the total body surface area. Brain edema was detected by calculating water content. Real time PCR, Western blot, and zymography were used to quantify MMP mRNA, protein, and enzyme activity levels. Each group was quantified at 3, 7, 24, and 72 h post thermal injury. Brain water content was significantly increased 7 through 72 h after burn. Expression of brain MMP-9 mRNA was significantly increased as early as 3 h after thermal injury compared to controls, remained at 7 h (p<0.01), and returned to control levels by 24 h. MMP-9 protein levels and enzyme activity began to increase at 7 h and reached significant levels between 7 and 24 h after thermal injury. While MMP-9 protein levels continued to increase significantly through 72 h, enzyme activity returned to control level. The increase in MMP-9 expression and activity, associated with increased BBB permeability following thermal injury, indicates that MMP-9 may contribute to observed cerebral edema in peripheral thermal injury.

[Identification of extracellular matrix metalloprotease 3 in the fetal membrane of the rat and its possible implication in the rupture of chorioamniotic membranes]

OBJECTIVE

Human corioamniotic membranes, or their equivalent in the rat, function as selective barrier during gestation and their rupture is part of the mechanisms implied in the labor. Molecular mechanisms carried out in this process are unknown.

TYPE OF STUDY

Experimental animal model.

MATERIAL AND METHODS

Corioamniotic membranes (obtained at the beginning of the labor) of rats with programmed and synchronous pregnancies were analized. The coexistence and distribution of metalloproteinase of extracellular-3 matrix (estromelisine) in these tissues were determined.

RESULTS

Secretion and tissue location of metalloproteinase of extracellular-3 matrix in fetal membranes were identified for the first time. Metalloproteinase of extracellular-3 matrix was immunolocated in the compact layer of the amnion and its secretion (by the membranes) was confirmed through electrophoresis, zimography and Western blot. By confocal microscopy it was verified that metalloproteinase of extracellular-3 matrix is located in the same places of that of extracellular-9 matrix.

CONCLUSIONS

Rupture of corioamniotic membranes relates to the expression and local activity of the metalloproteinases of extracellular matrix. The coexistence of metalloproteinase of extracellular-3 matrix in the amnion of the rat has been identified; this element is added to the biochemical process of rupture, since metalloproteinase of extracelular-3 matrix is an activator of that of extracellular-9 matrix. It is possible that the physiological function of this enzyme is implied, of a main way, in the process of rupture of corioamniotic membranes during the childbirth.

Increased expression of heparanase in overt diabetic nephropathy

In overt diabetic nephropathy (DNP), an increase in the permeability of the glomerular basement membrane (GBM) has been associated with a loss of negatively charged heparan sulfates (HS) in the GBM. Heparanase (HPSE), an endo-beta(1-4)-D-glucuronidase, can cleave HS and could be a potential candidate for the degradation of glomerular HS, leading to the development of proteinuria. We analyzed whether changes in HS expression are associated with HPSE expression in overt DNP. Immunofluorescence staining was performed to analyze HS, HPSE, and agrin core protein expression in kidney biopsies from patients with overt DNP and from rats and mice with streptozotocin (STZ)-induced diabetes. We also investigated the effect of transgenic HPSE overexpression in mice on glomerular HS and agrin expression. We demonstrate that the loss of GBM HS (-50%) and tubular HS (-60%) is associated with a four-fold increased HPSE expression in overt DNP. In addition, glomerular HPSE expression is upregulated in rats (messenger RNA (mRNA) 2.5-fold, protein three-fold) and mice (mRNA seven-fold, protein 1.5-fold) with STZ-induced diabetes. Furthermore, transgenic HPSE overexpression results in disappearance of HS, whereas expression of the core protein agrin remains unaltered. Our observations suggest that HPSE is involved in the pathogenesis of proteinuria in overt DNP by degradation of HS.

A cancer cell metalloprotease triad regulates the basement membrane transmigration program

Carcinoma cells initiate the metastatic cascade by inserting invasive pseudopodia through breaches in the basement membrane (BM), a specialized barrier of cross-linked, extracellular matrix macromolecules that underlies epithelial cells and ensheaths blood vessels. While BM invasion is the sine qua non of the malignant phenotype, the molecular programs that underlie this process remain undefined. To identify genes that direct BM remodeling and transmigration, we coupled high-resolution electron microscopy with an ex vivo model of invasion that phenocopies the major steps observed during the transition of carcinoma in situ to frank malignancy. Herein, a triad of membrane-anchored proteases, termed membrane type-1, type-2, and type-3 metalloproteinases, are identified as the triggering agents that independently confer cancer cells with the ability to proteolytically efface the BM scaffolding, initiate the assembly of invasive pseudopodia, and propagate transmigration. These studies characterize the first series of gene products capable of orchestrating the entire BM remodeling program that distinguishes the carcinomatous phenotype.

Integrin-linked kinase regulates Bergmann glial differentiation during cerebellar development

We demonstrate here that integrin-linked kinase (ILK), a serine/threonine kinase that binds to the beta1 integrin cytoplasmic domain, regulates cerebellar development. Mice with a CNS-restricted knock-out of the Ilk gene show perturbations in the laminar structure of the cerebellar cortex that are associated with defects in Bergmann glial fibers and the formation of meningeal basement membranes. Similar defects have been observed in mice lacking beta1 integrins in the CNS. ILK and beta1 integrins are coexpressed in Bergmann glial cells, and studies with primary cells in culture demonstrate that ILK and CDC42 are required for beta1-integrin-dependent glial process outgrowth. Consistent with these findings, the amount of GTP-bound CDC42 is impaired in the cerebellum of Ilk-deficient mice. We conclude that beta1 integrin, ILK and CDC42 are components of the signaling machinery that regulates glial process outgrowth in the cerebellum. We also show that granule cell precursor proliferation is affected in ILK-deficient mice, but our findings provide strong evidence that proliferative defects are a secondary consequence of ILK function in glia.

Glycosylation catalyzed by lysyl hydroxylase 3 is essential for basement membranes

Lysyl hydroxylase 3 (LH3) is a multifunctional enzyme possessing lysyl hydroxylase (LH), hydroxylysyl galactosyltransferase (GT) and galactosylhydroxylysyl glucosyltransferase (GGT) activities in vitro. To investigate the in vivo importance of LH3-catalyzed lysine hydroxylation and hydroxylysine-linked glycosylations, three different LH3-manipulated mouse lines were generated. Mice with a mutation that blocked only the LH activity of LH3 developed normally, but showed defects in the structure of the basement membrane and in collagen fibril organization in newborn skin and lung. Analysis of a hypomorphic LH3 mouse line with the same mutation, however, demonstrated that the reduction of the GGT activity of LH3 disrupts the localization of type IV collagen, and thus the formation of basement membranes during mouse embryogenesis leading to lethality at embryonic day (E) 9.5-14.5. Strikingly, survival of hypomorphic embryos and the formation of the basement membrane were directly correlated with the level of GGT activity. In addition, an LH3-knockout mouse lacked GGT activity leading to lethality at E9.5. The results confirm that LH3 has LH and GGT activities in vivo, LH3 is the main molecule responsible for GGT activity and that the GGT activity, not the LH activity of LH3, is essential for the formation of the basement membrane. Together our results demonstrate for the first time the importance of hydroxylysine-linked glycosylation for collagens.

Dystroglycan is selectively cleaved at the parenchymal basement membrane at sites of leukocyte extravasation in experimental autoimmune encephalomyelitis

The endothelial cell monolayer of cerebral vessels and its basement membrane (BM) are ensheathed by the astrocyte endfeet, the leptomeningeal cells, and their associated parenchymal BM, all of which contribute to establishment of the blood-brain barrier (BBB). As a consequence of this unique structure, leukocyte penetration of cerebral vessels is a multistep event. In mouse experimental autoimmune encephalomyelitis (EAE), a widely used central nervous system inflammatory model, leukocytes first penetrate the endothelial cell monolayer and underlying BM using integrin beta1-mediated processes, but mechanisms used to penetrate the second barrier defined by the parenchymal BM and glia limitans remain uninvestigated. We show here that macrophage-derived gelatinase (matrix metalloproteinase [MMP]-2 and MMP-9) activity is crucial for leukocyte penetration of the parenchymal BM. Dystroglycan, a transmembrane receptor that anchors astrocyte endfeet to the parenchymal BM via high affinity interactions with laminins 1 and 2, perlecan and agrin, is identified as a specific substrate of MMP-2 and MMP-9. Ablation of both MMP-2 and MMP-9 in double knockout mice confers resistance to EAE by inhibiting dystroglycan cleavage and preventing leukocyte infiltration. This is the first description of selective in situ proteolytic damage of a BBB-specific molecule at sites of leukocyte infiltration.

Protective effect of matrix metalloproteinase inhibitors against epidermal basement membrane damage: skin equivalents partially mimic photoageing process

BACKGROUND

The epidermal basement membrane (BM) plays important roles in adhesion between epidermis and dermis, and in controlling epidermal differentiation. The BM has been reported to be damaged in sun-exposed skin. Although matrix metalloproteinases (MMPs) are believed to be involved in the BM damage, there is no good in vitro model for examining BM damage by MMPs or for exploring methods to protect the BM.

OBJECTIVES

To examine the involvement of MMPs in BM damage and approaches to protect the BM from such damage by using an in vitro skin-equivalent (SE) model.

METHOD

SE was prepared by culturing human keratinocytes on contracted collagen gel including human fibroblasts. MMP-1, -2, -3 and -9, laminin 5 and type IV and VII collagens were determined by specific sandwich ELISAs, and MMP-2 and MMP-9 were analysed by gelatin zymography. Histological examination of SE was also carried out.

RESULTS

Despite production of BM components such as laminin 5 and type IV and VII collagens in SEs, BM was rarely observed at the dermal-epidermal junction. Several MMPs, such as MMP-1, -2, -3 and -9, were observed to be present in conditioned media and some of them were in active forms. Tissue inhibitor of metalloproteinase (TIMP)-2 was not detected, although TIMP-1 was present. Synthetic MMP inhibitors, CGS27023A and MMP-inhibitor I, which inhibit MMP-1, -2, -3 and -9, markedly augmented deposition of laminin 5 and type IV and VII collagens at the dermal-epidermal junction, resulting in the formation of continuous epidermal BM.

CONCLUSIONS

Our results indicate that MMPs are involved in the degradation of BM in SEs, and that MMP inhibitors exert a protective effect against BM damage.

PACE4 expression in mouse basal keratinocytes results in basement membrane disruption and acceleration of tumor progression

Collagen type IV degradation results in disruption and breakdown of the normal basement membrane architecture, a key process in the initiation of tumor microinvasion into the connective tissue. PACE4, a proprotein convertase, activates membrane type matrix metalloproteinases (MT-MMPs) that in turn process collagenase type IV. Because PACE4 is overexpressed in skin carcinomas and in vitro overexpression of PACE4 resulted in enhanced invasiveness, we investigated whether or not in vivo PACE4 expression leads to the acquisition of invasiveness and increased tumorigenesis. Two transgenic mouse lines were designed by targeting PACE4 to the epidermal basal keratinocytes. Transgenic keratinocytes showed increased processing of MT1-MMP and MT2-MMP resulting in collagenase IV activation and collagen type IV degradation. Higher collagenolytic activity partially disrupted normal basement membrane architecture favoring epithelial endophytic growth into the dermis and accelerating invasion and metastasis after chemical carcinogenesis. PACE4 overexpression resulted in enhanced susceptibility to carcinogenesis and tumor progression pointing to a new target for blocking tumor cell invasiveness.

PKCdelta regulates endothelial basal barrier function through modulation of RhoA GTPase activity

We have shown that PKCdelta enhanced microvascular endothelial basal barrier function, correlating with elevated RhoA GTPase activity and increased focal contact formation. In the current study, we investigated signaling pathways important in PKCdelta modulation of barrier function in unstimulated endothelial cell monolayers by assessing the effects of PKCdelta inhibition in endothelial cells (EC) derived from rat pulmonary artery (PAEC) and epididymus (FPEC). Rottlerin exposure or Ad PKCdeltadn infection significantly enhanced monolayer permeability in both EC. Immunofluorescence analyses demonstrated fewer stress fibers and focal contacts in rottlerin-treated or Ad PKCdeltadn-infected EC; yet, PKCdelta inhibition caused no significant changes in microtubule structures. These changes correlated with a reduction in both focal adhesion kinase (FAK) and RhoA GTPase activities. Microfilament stabilization significantly attenuated the focal contact and barrier disruptive effects of rottlerin. FAK overexpression did not blunt the effects of rottlerin-induced barrier dysfunction or stress fiber and focal contact disruption. Conversely, GFP-linked dominant active RhoA overexpression protected EC from stress fiber and focal contact disruption induced by both rottlerin exposure and overexpression of PKCdelta dominant negative protein. Additionally, PKCdelta immunoprecipitated with p190RhoGAP and p120RasGAP, modulators of RhoA activity. Thus, PKCdelta may regulate basal endothelial barrier function by stabilizing microfilaments and focal contacts by regulating RhoA GTPase activity through upstream modulators, p190RhoGAP and p120RasGAP.

Expression of matrix metalloproteinases-2 and -9 in intestinal tissue of patients with inflammatory bowel diseases

BACKGROUND/AIMS

Matrix metalloproteinases are major contributors in the breakdown and reconstitution of basement membranes and extracellular matrix in pathophysiological processes. We assessed the expression of matrix metalloproteinases-2 and -9 in intestinal tissue of patients with inflammatory bowel disease.

PATIENTS/METHODS

Resected tissue specimens from patients with Crohn's disease or ulcerative colitis and control tissue from patients with a colorectal carcinoma were used for enzyme-linked immunosorbent assay, zymography, activity assay, reverse transcription polymerase chain reaction and immunohistochemistry to evaluate the expression of these matrix metalloproteinases.

RESULTS

Matrix metalloproteinase-2 and more strongly matrix metalloproteinase-9 protein and mRNA were markedly increased in inflammatory bowel disease tissues, with the highest levels in severely inflamed tissues. Immunohistochemistry showed that matrix metalloproteinase-2 was present in the extracellular matrix of the submucosa, with a lower but more generalised expression in the severely inflamed regions. Matrix metalloproteinase-9 was most prominent in polymorphonuclear leukocytes and was increased, also in activity, in all inflammatory bowel disease tissues. An increased matrix metalloproteinase-9 expression in the extracellular matrix was observed in relation to the severity of inflammation.

CONCLUSIONS

Matrix metalloproteinases-2 and -9 are enhanced in the intestinal tissue and seem to be actively involved in the inflammatory and remodelling processes in inflammatory bowel disease, without major differences between CD and UC.

Diacylglycerol kinase activity in purified basolateral membranes of kidney tubules. I. Evidence for coupling with phospholipase C

The diacylglycerol kinase (DGK) catalyzes the phosphorylation of diacylglycerol (DAG) yielding phosphatidic acid (PA) signaling molecules which are involved in the modulation of different cell responses. The aim of this work was to characterize the DGK activity associated to the basolateral membranes (BLM) of kidney proximal tubules, in a native preparation that preserves the membrane microenvironment. The Arrhenius plot of DGK activity was non-linear, indicating a complex influence of the lipid environment of the native membrane. The formation of PA was strongly impaired by U73122, an inhibitor of PLC, whereas remained unmodified when exogenous DAG or PLC were added. The Mg.ATP2- complex is the true phosphoryl-donor substrate, and the very narrow peak of activation at pH 7.0 suggests that amino acids that dissociate at this pH, i.e. hystidine residues, play a role by acting in the coordination of the Mg2+ atoms. The renal DGK is almost completely blocked by 0.1 mM sphingosine, but it is insensitive to micromolar free Ca2+ concentrations and to R59499, the most potent inhibitor of the classical DGKs. Taken as a whole, these data suggest that the DGK isoform present in BLM of proximal tubules is different from those included in the type I family, and that membranous PLC could be the main source of DAG for DGK catalysis.

Les cholinestérases : des enzymes ancrées dans les membranes et les lames basales

Two proteins, ColQ and PRiMA, organize tetramers of acetylcholinesterase (AChE) and of butyrylcholinesterase (BChE) through peptide interactions. A short proline rich sequence in the N-terminal domain of ColQ or PRiMA associates four C-terminal extension of AChE or BChE. ColQ targets the enzymes in the basal lamina, PRiMA targets the enzymes at the plasma membrane. These complexes represent the mature proteins. The unassembled C-terminal extention of AChE is the key determinant recognized during the "quality control" of protein synthesis. Unassembled catalytic subunits are then degraded by the proteasome pathway. At the neuromuscular junction, ColQ/AChE represents the concentrated enzyme. The clusterisation of AChE depends upon ColQ through three sites of interactions: two different heparin binding domains in the collagen domain interact with heparan sulfate proteoglycan particularly the perlecan and the C-terminal non collagenic domain interacts with MuSK, the tyrosine kinase receptor organiser of the neuromuscular junction. The absence of ColQ and AChE has revealed that the excess of Ach stimulates more nicotinic receptors but probably not until their desensitization. Several morphological modifications may help the clearance of Ach. Conversely the synapse transmission fails during high frequency nerve stimulation.

Proteolytic enzymes and altered glycosylation modulate dystroglycan function in carcinoma cells

Alterations in the basement membrane receptor dystroglycan (DG) are evident in muscular dystrophies and carcinoma cells and characterized by a selective loss or modification of the extracellular alpha-DG subunit. Defects in posttranslational modifications of DG have been identified in some muscular dystrophies, but the underlying modifications in carcinoma cells have not yet been defined. We reveal here multiple posttranslational modifications that modulate the composition and function of DG in normal epithelial cells and carcinoma cells. We show that alpha-DG is shed from the cell surface of normal and tumorigenic epithelial cells through a proteolytic mechanism that does not require direct cleavage of either alpha- or beta-DG. Shedding is dependent on metalloprotease activity and the proprotein convertase furin. Surprisingly, furin is also found to directly process alpha-DG as a proprotein substrate, changing the existing model of DG composition. We also show that the glycosylation of alpha-DG is altered in invasive carcinoma cells, and this modification causes complete loss of laminin binding properties. Together, these data elucidate several novel events regulating the functional composition of DG and reveal defects that arise during cancer progression, providing direction for efforts to restore this link with the basement membrane in carcinoma cells.

Inhibition of MMP-dependent chemotaxis and amelioration of experimental autoimmune uveitis with a selective metalloproteinase-2 and -9 inhibitor

The chemotaxis of inflammatory cells depends on proteolytic disruption of extracellular matrix components. The metalloproteinases (MMP)-2 and -9 enable T-lymphocytes to pass through basement membranes. Selective inhibition of only MMP-2 and -9 almost completely abolished the ability of lymphocytes to digest collagen. The chemotaxis of lymphocytes was reduced 40%. In our in-vivo model of experimental autoimmune uveitis (EAU), 46% of the animals in the treated group remained disease-free, whereas all animals in the control group developed EAU. The mean activity of the disease was also statistically significantly reduced. The data suggest that selective MMP-2 and -9 inhibition might be a treatment option.

Heparanase gene silencing, tumor invasiveness, angiogenesis, and metastasis

BACKGROUND

Heparanase is an endoglycosidase that degrades heparan sulfate, the main polysaccharide constituent of the extracellular matrix and basement membrane. Expression of the heparanase gene is associated with the invasive, angiogenic, and metastatic potential of diverse malignant tumors and cell lines. We used gene-silencing strategies to evaluate the role of heparanase in malignancy and to explore the therapeutic potential of its specific targeting.

METHODS

We designed plasmid vectors to express hammerhead ribozymes or small interfering RNAs (siRNAs) directed against the human or mouse heparanase mRNAs. Human breast carcinoma (MDA-MB-435) and mouse lymphoma (Eb) and melanoma (B16-BL6) tumor cell lines, which have naturally high levels of endogenous heparanase or have been genetically engineered to overexpress heparanase, were transfected with anti-heparanase ribozyme or siRNA. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and measurements of enzymatic activity were used to confirm the efficient silencing of heparanase gene expression. Cells transfected with the anti-heparanase ribozyme and siRNA vectors were tested for invasiveness in vitro and metastatic dissemination in animal models of experimental and spontaneous metastasis.

RESULTS

Compared with cells transfected with control constructs, cells transfected with the anti-heparanase ribozyme or siRNA vectors had profoundly reduced invasion and adhesion in vitro, regardless of cell type, and expressed less heparanase. In vivo, tumors produced by cells transfected with the anti-heparanase ribozyme and siRNA vectors were less vascularized and less metastatic than tumors produced by cells transfected with the control vectors. Mice injected with cells transfected with the anti-heparanase ribozyme and siRNA vectors lived longer than mice injected with control cells.

CONCLUSIONS

The association of reduced levels of heparanase and altered tumorigenic properties in cells with anti-heparanase ribozyme- or siRNA-mediated gene-silencing vectors suggests that heparanase is important in cancer progression. Heparanase gene silencing has potential use as a target for anticancer drug development.

PKN3 is required for malignant prostate cell growth downstream of activated PI 3-kinase

Chronic activation of the phosphoinositide 3-kinase (PI3K)/PTEN signal transduction pathway contributes to metastatic cell growth, but up to now effectors mediating this response are poorly defined. By simulating chronic activation of PI3K signaling experimentally, combined with three-dimensional (3D) culture conditions and gene expression profiling, we aimed to identify novel effectors that contribute to malignant cell growth. Using this approach we identified and validated PKN3, a barely characterized protein kinase C-related molecule, as a novel effector mediating malignant cell growth downstream of activated PI3K. PKN3 is required for invasive prostate cell growth as assessed by 3D cell culture assays and in an orthotopic mouse tumor model by inducible expression of short hairpin RNA (shRNA). We demonstrate that PKN3 is regulated by PI3K at both the expression level and the catalytic activity level. Therefore, PKN3 might represent a preferred target for therapeutic intervention in cancers that lack tumor suppressor PTEN function or depend on chronic activation of PI3K.

Human meprin alpha and beta homo-oligomers: cleavage of basement membrane proteins and sensitivity to metalloprotease inhibitors

Meprin is a zinc endopeptidase of the astacin family, which is expressed as a membrane-bound or secreted protein in mammalian epithelial cells, in intestinal leucocytes and in certain cancer cells. There are two types of meprin subunits, alpha and beta, which form disulphide-bonded homo- and hetero-oligomers. Here we report on the cleavage of matrix proteins by hmeprin (human meprin) alpha and beta homo-oligomers, and on the interactions of these enzymes with inhibitors. Despite their completely different cleavage specificities, both hmeprin alpha and beta are able to hydrolyse basement membrane components such as collagen IV, nidogen-1 and fibronectin. However, they are inactive against intact collagen I. Hence the matrix-cleaving activity of hmeprin resembles that of gelatinases rather than collagenases. Hmeprin is inhibited by hydroxamic acid derivatives such as batimastat, galardin and Pro-Leu-Gly-hydroxamate, by TAPI-0 (tumour necrosis factor alpha protease inhibitor-0) and TAPI-2, and by thiol-based compounds such as captopril. Therapeutic targets for these inhibitors are MMPs (matrix metalloproteases), TACE (tumour necrosis factor alpha-converting enzyme) and angiotensin-converting enzyme respectively. The most effective inhibitor of hmeprin alpha in the present study was the naturally occurring hydroxamate actinonin ( K(i)=20 nM). The marked variance in the cleavage specificities of hmeprin alpha and beta is reflected by their interaction with the TACE inhibitor Ro 32-7315, whose affinity for the beta subunit (IC50=1.6 mM) is weaker by three orders of magnitude than that for the alpha subunit ( K(i)=1.6 microM). MMP inhibitors such as the pyrimidine-2,4,6-trione derivative Ro 28-2653 that are more specific for gelatinases do not bind to hmeprin, presumably due to the subtle differences in the mode of zinc binding and active-site structure between the astacins and the MMPs.

Stromal Cell-Derived Factor-1α Promotes Melanoma Cell Invasion across Basement Membranes Involving Stimulation of Membrane-Type 1 Matrix Metalloproteinase and Rho GTPase Activities

Tissue invasion by tumor cells involves their migration across basement membranes through activation of extracellular matrix degradation and cell motility mechanisms. Chemokines binding to their receptors provide chemotactic cues guiding cells to specific tissues and organs; they therefore could potentially participate in tumor cell dissemination. Melanoma cells express CXCR4, the receptor for the chemokine stromal cell-derived factor-1alpha (SDF-1alpha). Using Matrigel as a model, we show that SDF-1alpha promotes invasion of melanoma cells across basement membranes. Stimulation of membrane-type 1 matrix metalloproteinase (MT1-MMP) activity by SDF-1alpha was necessary for invasion, involving at least up-regulation in the expression of this metalloproteinase, as detected in the highly metastatic BLM melanoma cell line. Moreover, SDF-1alpha triggered the activation of the GTPases RhoA, Rac1, and Cdc42 on BLM cells, and expression of dominant-negative forms of RhoA and Rac1, but not Cdc42, substantially impaired the invasion of transfectants in response to SDF-1alpha, as well as the increase in MT1-MMP expression. Furthermore, CXCR4 expression on melanoma cells was notably augmented by transforming growth factor-beta1, a Matrigel component, whereas anti-transforming growth factor-beta antibodies inhibited increases in CXCR4 expression and melanoma cell invasion toward SDF-1alpha. The identification of SDF-1alpha as a potential stimulatory molecule for MT1-MMP as well as for RhoA and Rac1 activities during melanoma cell invasion, associated with an up-regulation in CXCR4 expression by interaction with basement membrane factors, could contribute to better knowledge of mechanisms stimulating melanoma cell dissemination.

Altered expression of NDST-1 messenger RNA in puromycin aminonucleoside nephrosis

Sulfated portions of glycosaminoglycan (GAG) side chains in heparan sulfate proteoglycan (HSPG) are thought to play an important role in charge-dependent selectivity of glomerular filtration against plasma proteins. Heparan sulfate N-acetylglucosamine N-deacetylase/adenosine 3'-phosphate 5'-phosphosulfate: unsubstituted glucosamine N-sulfotransferase (NDST) is the key enzyme regulating sulfation of GAG chains. In this study we investigated transcriptional expression of NDST-1, 1 of 4 isozymes of NDST, in glomeruli of rats with puromycin aminonucleoside (PAN) nephrosis. Nephrosis was induced in rats with a single intraperitoneal injection of 150 mg/kg PAN. On days 10 and 35, expression of NDST-1 messenger RNA (mRNA) in glomeruli was analyzed with the use of Northern-blot analysis. Immunohistochemical studies were also performed with the use of monoclonal antibodies that react specifically with the N-sulfated portion of the GAG chain of HSPG and agrin, a major core protein of HSPG in glomerular basement membrane (GBM). In addition, we studied the expression of NDST-1 mRNA in cultured glomerular epithelial cells (GECs) and glomerular mesangial cells in the presence of PAN. On day 10, when significant proteinuria developed, the ratios of glomerular expression of NDST-1 mRNA against glyceraldehyde-phosphate dehydrogenase mRNA in PAN-treated rats were decreased to 48% +/- 6% of those in controls (P<.05). Immunohistochemical studies revealed that staining for N-sulfated GAG chains of HSPG on GBM was markedly reduced on day 10 in PAN-treated rats but that staining for agrin was unchanged. In contrast, on day 35, when PAN-treated rats recovered from proteinuria, we noted no differences in glomerular expression of NDST-1 mRNA and staining intensity for N-sulfated GAG chains on GBM between PAN-treated rats and controls. Incubation of GECs for 24 hours in the presence of 50 ng/mL PAN resulted in the reduction of the expression of NDST-1 mRNA (67% +/- 12% of those in controls, P<.05). In summary, we found alteration of the expression of NDST-1 mRNA, accompanying a loss of N-sulfated GAG chains of HSPG on GBM without changes in the core protein agrin, in the course of PAN nephrosis. These data suggest an important role for this enzyme in heparan sulfate assembly in GBM and GEC and in the pathogenesis of proteinuria in PAN nephrosis.

Direct cell-cell interaction enhances pro-MMP-2 production and activation in co-culture of laryngeal cancer cells and fibroblasts: involvement of EMMPRIN and MT1-MMP

Matrix metalloproteinases-2 (MMP-2, gelatinase A) has been regarded as a crucial enzyme for tumor progression, invasion, and metastasis by its capability to degrade the basement membrane components, and its activation process is critical for tumor development. Recently, EMMPRIN/CD147, which is a member of immunoglobulin superfamily, has been reported to be highly expressed in tumor cells and induce production of MMPs from fibroblasts adjacent to the tumor cells. In this study, we demonstrated that production of pro- and active forms of MMP-2 by human dermal fibroblasts was enhanced by the direct cell-cell contact with co-cultured HEp-2 cells derived from a human laryngeal epidermoid carcinoma. The results from immunoblotting and reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated that HEp-2 cells express a higher level of EMMPRIN but only a low level of MMP-2 and membrane type 1-matrix metalloproteinase (MT1-MMP), whereas fibroblasts express a higher level of MMP-2 and MT1-MMP and a low level of EMMPRIN. In a mixed co-culture with direct cell-cell contacts, co-cultured HEp-2 cells stimulated the pro- and active MMP-2 production from fibroblasts, but not in a separated co-culture through polycarbonate membrane. Production of pro/active MMP-2 and MT1-MMP (activator of pro-MMP-2) in fibroblasts was induced by the addition of membrane fractions prepared from HEp-2 cells to the fibroblast culture, and the induction was suppressed by the EMMPRIN depletion after immunoprecipitation, signifying the participation of EMMPRIN for the induction and activation of MMP-2. Our results suggest an importance of the direct cell-cell interaction involving EMMPRIN rather than humoral factors such as cytokines for pro-MMP-2 production and activation followed by tumor progression, invasion, and metastasis in laryngeal cancer.

Effect of vitamin E and vitamin C supplementation on antioxidative state and renal glomerular basement membrane thickness in diabetic kidney

The aim of this study was to analyze the effect of vitamins C and E on malondialdehyde (MDA) content and activities of key antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) as well as glomerular basement membrane (GBM) thickness in streptozotocin-induced diabetic kidney in rats. Wistar male rats were divided into following groups (12 rats each): the control, diabetic rats, diabetic rats whose drinking water was supplemented with vitamin C in a dose of 1.0 g/l or diet was supplemented with 200 mg of vitamin E/100 g fodder. Body weight, blood glucose and HbA1C levels and 24-hour urinary albumin excretion (UAE) were studied every week (0-12 weeks). After 6 and 12 weeks, MDA content and activities of SOD, CAT and GSH-Px were measured in the kidney homogenate supernatants. Electron micrographs of glomeruli were scanned and morphometric investigations were performed by means of computer image analysis system to compare GBM thickness. The blood glucose and HbA1C concentrations and UAE in diabetic rats were significantly higher than in the control group. An increase in the MDA level and decrease in the SOD, CAT and GSH-Px activities in the kidney of diabetic rats were observed after 6 and 12 weeks of experiment. Administration of vitamins C and E did not affect body weight, blood glucose and HbA1C levels. Both vitamin C and vitamin E decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in the kidneys of diabetic rats as well as reduced UAE, decreased kidney weight and GBM thickness. The results indicate the potential utility of antioxidant vitamins in the protection against the development of diabetic nephropathy.

IL-12 regulates an endothelial cell-lymphocyte network: effect on metalloproteinase-9 production

IL-12 is key cytokine in innate immunity and participates in tumor rejection by stimulating an IFN-gamma-mediated response characterized by CD8(+) mediated-cytotoxicity, inhibition of angiogenesis, and vascular injury. We previously demonstrated that activated lymphocytes stimulated with IL-12 induced an angiostatic program in cocultured vascular endothelial cells. In this study, we have extended this observation showing that a reciprocal modulation of cellular responses occurs. Actually, the presence of endothelial cells enhanced the inhibitory effect of IL-12 on metalloproteinase-9 expression in activated PBMC as well as their ability to transmigrate across an extracellular matrix. IL-12 triggered intracellular signaling, as indicated by STAT-1 activation, appeared to mainly operative in activated CD4 (+) cells challenged with IL-12, but it was also initiated in CD8(+) lymphocytes in the presence of endothelial cells. On the other hand, stimulated PBMC reduced the expression and the activity of metalloproteinase-9, up-regulated that of tissue inhibitor metalloproteinase-1, and stimulated the STAT-1 pathway in cocultured endothelial cells. We used neutralizing Abs to show that the IFN-inducible protein 10 (CXCL10) and monokine-induced by IFN-gamma (CXCL9) chemokines produced by both PBMC and endothelial cells are pivotal in inducing these effects. Altogether these results suggest the existence of an IL-12-regulated circuit between endothelium and lymphocytes resulting in a shift of proteolytic homeostasis at site of tissue injury.

Disruption of basement membrane, extracellular matrix metalloproteinases and E-cadherin in renal-cell carcinoma

A retrospective study was performed to determine the prognostic value of Basement Membrane (BM) integrity, Matrix Metalloproteinases (MMPs) and E-Cadherin expression in renal cell carcinoma (RCC).

MATERIALS AND METHODS

An immunohistochemical study on laminin and collagen IV, MMPs 1 and 2, and E-Cadherin was carried out on 71 RCCs. BM fragmentation was considered taking 75% as a cut-off. MMP 1 and MMP2 immunostaining, as well as E-Cadherin was considered taking 25% as a cut-off.

RESULTS

An inverse relationship was seen between E-Cadherin with laminin, collagen IV and MMPs. More than 75% loss of laminin, collagen IV and E-Cadherin, as well as higher expression of MMPs, were associated with symptoms, tumoral size and worse grade. Loss of collagen IV and E-Cadherin were of prognostic value.

CONCLUSION

Both BM and E-Cadherin are good prognostic markers. MMPs patterns show a relationship between BM proteins and E-Cadherin, but evaluation is more time-consuming and provide no better prognostication; consequently they are not useful in routine clinical applications.

Enhanced degradation of proteins of the basal lamina and stroma by matrix metalloproteinases from the salivary glands of Sjögren's syndrome patients: correlation with reduced structural integrity of acini and ducts

OBJECTIVE

To determine the effect of matrix metalloproteinase (MMP) activity from the labial salivary glands (LSGs) of Sjögren's syndrome (SS) patients on proteins of the extracellular matrix (ECM) that form the basal lamina and stroma, and to compare this effect with the structural integrity of acini and ducts as well as the functionality of the LSGs.

METHODS

Gelatinase activity was determined by zymography. The digestion pattern of extracellular matrix (ECM) macromolecules was detected by gel electrophoresis and quantified by densitometry. The structural integrity of acini and ducts was evaluated by light and electron microscopy. Secretory function was evaluated by measuring unstimulated salivary flow and by scintigraphy.

RESULTS

LSG extracts showed increased levels of proteolytic activity toward purified proteins of the basal lamina (laminin and type IV collagen) and stroma (types I and III collagen and fibronectin). Enhanced degradation was most evident for fibronectin, laminin, and type IV collagen. Analysis of the ultrastructure of the acinar and ductal basal lamina revealed abnormalities ranging from disorganization to disappearance of this ECM structure. These changes were paralleled by an important loss of microvilli on the apical surface, as well as decreased unstimulated salivary flow. Interestingly, the results were similar in LSGs from all SS patients, regardless of the proximity of infiltrating mononuclear cell foci.

CONCLUSION

Our observation that the proteolytic action of MMPs toward ECM macromolecules is increased in SS patients provides a rationale for understanding the dramatic changes in the structural organization observed in the basal lamina and apical surface of acini in these patients. The results provide new evidence that acinar and ductal cells from the LSGs of SS patients display a molecular potential, with increased capacity to markedly disorganize their ECM environment and, thus, damage their architecture and functionality.

Mechanism of matrix accumulation and glomerulosclerosis in spontaneously hypertensive rats

BACKGROUND

Renal interstitial fibrosis and thickening of the glomerular basement membrane are associated with hypertension. However, the mechanism of matrix accumulation is unclear. Spontaneously hypertensive rats (SHR) develop hypertension at between 2 and 6 weeks of age.

METHODS

To test the hypothesis that increased matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) contribute to the pathomechanisms of hypertensive nephropathy, the cortex and medulla of male SHR at 2 and 6 weeks were analyzed for MMP-2, MMP-7, and MMP-9 by gelatin and elastin gel zymography. The levels of TIMP-4 were measured by western blot analysis. The bands in blots were scanned and normalized with actin. To localize MMP-2 and TIMP-4 in situ, immuno-labeling was performed. To determine proteinuresis, urinary protein was measured by Bio-Rad dye binding assay. The mean arterial pressure (mmHg) was measured in Inactin-anesthetized rats by a PE-50 catheter in the femoral artery. Age-sex matched normotensive Wistar rats (NWR) were used as controls and grouped: (1). SHR, 2 weeks; (2). SHR, 6 weeks; (3). NWR, 2 weeks; and (4). NWR, 6 weeks (n = 6 in each group).

RESULTS

Levels of cortex MMP-2 and MMP-9 were increased in 6 week SHR as compared with NWR. In the medulla, MMP-9 and MMP-7 were increased, but there was no change in MMP-2. The levels of cortex TIMP-4 tended to increase but insignificantly. In contrast, there were significant increases in the levels of TIMP-4 in the medulla of 6 week SHR as compared with 2 week SHR or NWR. In addition, there were substantial elastinolytic activity in the cortex of 6 week SHR. The in situ labeling suggested no TIMP-4 in the glomeruli. There was substantial TIMP-4 in the epithelial layer of tubules. The levels of fibrotic collagen were significantly higher in both the glomeruli and tubular interstitium. Urinary protein excretion was increased significantly in 6 week SHR when compared with other groups. The mean arterial pressure was 1.6-fold higher in 6 week SHR than in controls.

CONCLUSION

These results suggest that increased MMP-2 and MMP-9 activity contributes to glomerular injury and hypertensive remodeling. The increased levels of TIMP-4 in the medulla may inhibit the collagenolytic activity of MMP but is unable to inhibit the elastinolytic activity. An important role of MMP-2, MMP-9, and TIMP-4 in hypertensive remodeling of the cortex and medulla in the SHR is demonstrated.

Doxycycline decreases proteinuria in glomerulonephritis

Treatment options for crescentic glomerulonephritis include the use of steroids, cytotoxic therapy, and, in severe cases, intravenous immunoglobulins and plasmapheresis. Injury and lysis of capillary glomerular basement membrane, which is made up of type IV collagen, laminin, fibronectin, and proteoglycans, by serine proteinases and matrix metalloproteinases (MMPs) likely is an important participant in the pathogenesis of crescentic glomerulonephritis. Tetracycline derivatives inhibit not only the activity of MMPs, but also their production, and have been investigated for the treatment of disorders in which the MMP system becomes amplified, such as degenerative osteoarthritis, periodontitis, cancer, and abdominal aortic aneurysm. We report an interesting case of crescentic glomerulonephritis in a young man who was treated with cyclophosphamide and prednisone. The patient developed steroid-induced acne that was treated with long-term oral doxycycline therapy. During the period the patient was administered doxycycline, proteinuria decreased by 70% and recurred when doxycycline was stopped. To our knowledge, this is the first report of possible benefits of a metalloproteinase inhibitor (doxycycline) in glomerulonephritis in humans. Future studies are urgently required to explore the option of metalloproteinase inhibitors in the treatment of proliferative glomerulonephritis.

Subepithelial basement membrane immunoreactivity for matrix metalloproteinase 9: association with asthma severity, neutrophilic inflammation, and wound repair

BACKGROUND

Asthma likely involves an active injury and repair process, including components such as neutrophils and matrix metalloproteinase 9 (MMP-9). Although MMP-9 is increased in lavage fluid and sputum in patients with asthma, controversy exists as to the role of tissue MMP-9.

OBJECTIVE

The purpose of this study was to determine whether increases in submucosal cellular MMP-9, matrix MMP-9 (subepithelial basement membrane [SBM]), or both would be associated with severe asthma, neutrophilic inflammation, and wound repair.

METHODS

Immunohistochemical staining and analyses of MMP-9, inflammatory cells, transforming growth factor beta, and collagen I were performed in endobronchial biopsy specimens, bronchoalveolar lavage fluid, or both from 38 patients with severe asthma and compared with results in 10 patients with mild asthma, 8 patients with moderate asthma, and 10 healthy control subjects.

RESULTS

A significantly greater proportion of patients with severe asthma demonstrated MMP-9 staining of the SBM than control subjects (P =.02). Bronchoalveolar lavage MMP-9 levels were also increased in patients with severe asthma (P =.0004). The numbers of submucosal neutrophils and macrophages, but not eosinophils, were significantly higher in asthmatic individuals with MMP-9 staining of the SBM (P =.004 and P =.01, respectively). However, the presence of SBM MMP-9 was associated with a high correlation between lavage and tissue eosinophils (r = 0.58, P =.009). Although the SBM thickness did not differ between groups, higher numbers of transforming growth factor beta-positive cells were seen in subjects with SBM MMP-9 staining. Pulmonary function was significantly lower in those asthmatic subjects with SBM staining.

CONCLUSIONS

These results suggest that localized tissue MMP-9 might play an important role in wound repair and cell trafficking.

Differentiation-dependent induction of CYP1A1 in cultured rat small intestinal epithelial cells, colonocytes, and human colon carcinoma cells: basement membrane-mediated apoptosis

Rat small intestinal epithelial cells and human colon adenocarcinoma cells cultured on Matrigel expressed the differentiation specific enzyme, sucrase-isomaltase, as determined by indirect immunofluorescence. Rat small intestinal epithelial cells, rat colonocytes, and human colon adenocarcinoma cells developed an altered morphology when cultured on Matrigel and became apoptotic within 24-48 h. Benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin caused a 2- and 5-fold induction, respectively, of ethoxyresorufin-o-deethylase activity in rat small intestinal epithelial cells cultured on Matrigel. Benzo[a]pyrene- or 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced ethoxyresorufin-o-deethylase activity in rat small intestinal epithelial cells cultured on plastic was not detected. 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment caused a 14-fold induction of transfected, rat CYP1A1-promoter-luciferase activity in rat small intestinal epithelial cells cultured on Matrigel. Benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment induced ethoxyresorufin-o-deethylase activity by 6- and 1.6-fold, respectively in rat colonocytes cultured on Matrigel. Induction of ethoxyresorufin-o-deethylase activity was not observed in rat colonocytes cultured on plastic. CYP1A1-promoter-luciferase activity was induced 3-fold by 2,3,7,8-tetrachlorodibenzo-p-dioxin in rat colonocytes cultured on Matrigel. Induction of CYP1A1-promoter-luciferase activity in rat small intestinal epithelial cells or rat colonocytes cultured on plastic was not observed. Ethoxyresorufin-o-deethylase activity in human colon adenocarcinoma cells, cultured on either plastic or Matrigel, was induced 7-fold by benzo[a]pyrene. 2,3,7,8-Tetrachlorodibenzo-p-dioxin-induced ethoxyresorufin-o-deethylase activity was 2-fold greater in human colon adenocarcinoma cells cultured on Matrigel compared to cells cultured on plastic. Extracellular matrix-mediated differentiation and apoptosis of intestinal cells provide in vitro systems for study of the regulation of CYP1A1 expression, carcinogen activation in the gut and mechanism(s) of apoptosis of colon cancer cells.

Uptake of dipeptide and beta-lactam antibiotics by the basolateral membrane vesicles prepared from rat kidney

The transport of dipeptides and beta-lactam antibiotics across the rat renal basolateral membrane was examined. The initial uptake of glycylsarcosine and cefadroxil by rat renal basolateral membrane vesicles was inhibited by the presence of all the di- and tripeptides and beta-lactam antibiotics that were tested in this study. However, the uptake of both substrates was not inhibited by glycine, an amino acid. The initial uptake of zwitterionic beta-lactam antibiotics, cefadroxil, cephradine, and cephalexin, was stimulated by preloaded glycylsarcosine (countertransport effect). On the other hand, the uptake of dianionic beta-lactam antibiotics, ceftibuten and cefixime, was not affected. A concentration-dependent initial uptake of glycylsarcosine and cefadroxil suggested the existence of a carrier-mediated mechanism, whereas the transport of ceftibuten did not show any saturated uptake. The transporter that participates in the permeation of dipeptides and beta-lactam antibiotics across basolateral membranes showed lower affinity than did PEPT1 and PEPT2. This is the first study that showed an evidence for a peptide transporter, expressed in the rat renal basolateral membrane, that recognizes zwitterionic beta-lactam antibiotics using basolateral membrane vesicles isolated from normal rat kidney.

The involvement of matrix metalloproteinases in basement membrane injury in a murine model of acute allergic airway inflammation

BACKGROUND

Airway remodelling in asthma such as subepithelial fibrosis is thought to be the repair process that follows the continuing injury as of chronic airway inflammation. However, how acute allergic inflammation causes tissue injury in the epithelial basement membrane in asthmatic airways remains unclear. Matrix metalloproteinases (MMPs) capable of degrading almost all of the extracellular matrix components have been demonstrated to be involved in cell migration through the basement membrane in vivo and in vitro.

OBJECTIVE

We investigated the alterations of matrix construction and the role of MMPs in matrix degradation in the subepithelium during acute allergic airway inflammation.

METHODS

Airway inflammation, the ultrastructure of the subepithelium and injury of types III and IV collagen in tracheal tissues from ovalbumin (OVA)-sensitized mice after OVA inhalation with or without the administration of tissue inhibitor of metalloproteinase-2 (TIMP-2) and dexamethasone were evaluated by cell counting in bronchoalveolar lavage (BAL) fluids, electron microscopy and immunohistochemistry, respectively.

RESULTS

The disruption of the lamina densa and matrix construction and the decrease of the immunoreactivity for type IV collagen in subepithelium were observed in association with the accumulation of inflammatory cells in airways 3 days after OVA inhalation. This disorganization of the matrix components in the subepithelium, as well the cellular accumulation, was abolished by the administration of TIMP-2 and dexamethasone. The immunoreactivity for type IV collagen in the subepithelium in OVA-inhaled mice returned to the level of that in saline-inhaled mice 10 days after inhalation in association with a decrease of the cell numbers in the BAL fluid. The immunoreactivity for type III collagen was changed neither 3 nor 10 days after OVA inhalation.

CONCLUSION

These results suggest that epithelial basement membrane gets injured by, at least in part, MMPs as a consequence of cell transmigration through the membrane during acute allergic airway inflammation.

Case of primary malignant hemangiopericytoma of the heart expressing basement membrane-degradable enzymes

An echocardiogram demonstrated a large tumor in the left atrium of a 47-year-old woman with sudden heart failure. Emergent cardiotomy showed that the tumor arose from the left atrial wall, and almost entirely occupied the left atrium. Grossly, the tumor had partly undergone necrosis. Histologically, the tumor consisted predominantly of round to polygonal cells with ill-defined cell borders surrounding 'stag horn'-shaped blood vessels. Mitosis was frequently seen with abnormal mitotic figures. Immunohistochemically, the tumor cells diffusely expressed vimentin and focally expressed factor XIIIa and human leukocyte antigen-DR. A few tumor cells expressed S-100 protein or alpha-smooth muscle actin. Histopathological diagnosis was malignant hemangiopericytoma of the left atrium. Most tumor cells expressed matrix metalloproteinase (MMP)-2 and MMP-3, and several cells expressed MMP-9, all of which are capable of degrading a major component of basement membrane (i.e. type IV collagen). Furthermore, tumor cells expressed membrane type 1 MMP and tissue inhibitor of metalloproteinase-2, both of which are required for activation of proMMP-2. Fourteen months after the surgical removal, she died of systemic recurrent tumors.

The electrical resistance breakdown assay determines the role of proteinases in tumor cell invasion

The electrical resistance breakdown of the Madin-Darby canine kidney (MDCK) cell monolayer provides a continuous assay system for cancer invasion that detects functional changes before morphological alterations. In this study, we address the question of whether physical contact between tumor cell and epithelial monolayer is a prerequisite for tumor cell invasion. When human melanoma cells were seeded directly (i.e., physical contact) on top of an electrically tight epithelial cell layer (5,800 +/- 106 Omega x cm2), electrical monolayer leakage led to an 18 +/- 3% reduction of transepithelial electrical resistance within 24 h. However, when melanoma cells were seeded close to the basolateral surface of the epithelial cell monolayer but separated by a filter membrane (i.e., no physical contact), electrical leakage occurred even more quickly (42 +/- 3% reduction in 24 h). Atomic force microscopy detected discrete structural changes between cells. Electrical leakage was effectively blocked by alpha2-macroglobulin or ilomastat, inhibitors of matrix metalloproteinases. We conclude that exocytosis of soluble proteases causes electrical breakdown of the MDCK monolayer, independently of physical contact between tumor cells and the monolayer.

Long-term overexpression of membrane type-1 matrix metalloproteinase and matrix metalloproteinase-2 in oleic acid-induced pancreatitis in rats

INTRODUCTION

The matrix metalloproteinase (MMP) plays important roles in extracellular matrix turnover. However, little is known about the roles of MMP-2 and type IV collagen, and the relationship between MMP-2 and membrane type-1 matrix metalloproteinase (MT1-MMP) during progressive destruction of acinar cells in pancreatitis.

AIMS AND METHODOLOGY

To examine the serial changes in the expression and activity of MMP-2 and expression of MT1-MMP and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in rats after induction of pancreatitis by intraductal infusion of oleic acid, and to determine protein concentrations by Western blot analysis and localization of type IV collagen by immunostaining.

RESULTS

Gelatinolytic activity of pro-and active MMP-2 and concentrations of MT1-MMP protein, as determined by zymography and Western blot analysis, respectively, increased significantly from 6 hours to day 42 after intraductal infusion of oleic acid. TIMP-2 mRNA expression was significantly higher than that at time 0 throughout the study period, and gelatinolytic activity of active MMP-2 increased from day 3 to day 42. In addition, immunoreactivity for type IV collagen was detected as a discontinuous line along the basement membranes of ducts, vessels, tubular complexes, and acinar cells.

CONCLUSION

Our findings indicate that long-term increases of gelatinolytic activity of active MMP-2 cause continuous disorganization of type IV collagen in basement membranes during progressive atrophy of pancreatic gland in oleic acid-induced pancreatitis, and that MT1-MMP and TIMP-2 work as activating factors during proMMP-2 activation. Moreover, basement membranes disorganization in the sustentacula of acinar cells and duct epithelia seems to participate in continuous derangement of acinar cells and duct epithelium.

Upregulation of duodenal calcium absorption by poly-unsaturated fatty acids: events at the basolateral membrane

Poly-unsaturated fatty acids, especially of the n-3 series, have a beneficial effect in treatment of osteoporosis in the elderly. Duodenal calcium absorption is a particularly vulnerable aspect of the development of this disease. It has been shown that the process of calcium transport through the rat duodenal enterocyte takes place in essentially three steps: entry of calcium through channels in the brush border (apical membrane), transcellular transport through the cytoplasm by calbindin and extrusion at the basolateral membrane by Ca(2+)-ATPase and a Ca(2+)-Na(+)exchanger which is driven by Na(+), K(+)-ATPase. This paper presents a hypothesis that poly-unsaturated fatty acids can modulate both Ca(2+)-ATPase and Na(+), K(+)-ATPase activity either by a direct action on the enzyme or by phosphorylation processes via protein kinases A and C and thus exert their positive influence on calcium absorption in this manner.

Specific expression of matrix metalloproteinases 1, 3, 9 and 13 associated with invasiveness of breast cancer cells in vitro

Several matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were studied in highly invasive (MDA-MB-231) and slightly invasive (MCF-7, T47D, BT-20) breast cancer cell lines. Investigations were carried out at the protein level and/or at the mRNA level, either in cells cultured as monolayers on plastic, or in cells seeded on a thin layer of Matrigel basement membrane matrix. Analysis of MMP expression by RT-PCR showed expression of MMP-1. MMP-3, and MMP-13 in highly invasive MDA-MB-231 cells, but not in slightly invasive cell lines. The extracellular secretion of MMP-1 and MMP-3 by MDA-MB 231 cells could be also shown by ELISA. TIMP-1 and TIMP-2 mRNAs were found in all cell lines, however, the extracellular secretion of both TIMPs was much higher in MDA-MB-231 cells than in the other cell lines. When the cells were cultured on Matrigel matrix, MMP-9 expression was induced in MDA-MB-231 cells only, as assessed by RT-PCR and zymography experiments. The invasive potential of MDA-MB-231 cells evaluated in vitro through Matrigel was significantly inhibited by the MMP inhibitor BB-2516, by 25% and 50% at the concentrations of 2 x 10(-6) M and 10(-5) M, respectively. In conclusion, our data show that highly invasive MDA-MB-231 cells but not slightly invasive T47D, MCF-7 and BT-20 cells express MMP-1, MMP-3, MMP-9 and MMP-13. MMP-9 which is specifically up-regulated by cell contact to Matrigel, may play a key role in the invasiveness of MDA-MB-231 cells through basement membranes.