Influence of oleic acid on the expression, activation and activity of gelatinase A produced by oncogene-transformed human bronchial epithelial cells

Screening of matrix metalloproteinase inhibitors by microanalysis with fluorescence detection

Capillary electrophoresis has emerged as a small-scale analytical tool for enzyme assays. It is not only used to analyze and follow-up enzymatic reactions in an offline mode, but the reaction can also be performed online, inside the capillary, where the reaction products are formed and analyzed. In this way, an integrated setup is obtained which allows a higher degree of automation and miniaturization in analytical systems. This chapter presents an electrophoretically mediated microanalysis for in vitro characterization and screening of matrix metalloproteinase inhibitors.

Oleic acid promotes MMP-9 secretion and invasion in breast cancer cells

Epidemiological and animal studies suggest an association between dietary fatty acids and an increase risk of developing breast cancer. Obesity, which is characterized by hyperlipidemia and an elevation of circulating free fatty acids (FFAs), is also associated with enhanced cancer risk. In breast cancer cells, the FFA oleic acid (OA) induces migration, proliferation, prolong survival, invasion, an increase in cellular Ca(2+) concentration, MEK1/2, ERK1/2, FAK and Src activation. However, the role of OA on MMP-9 secretion and invasion has not been studied in detail. We demonstrate here that stimulation of MDA-MB-231 breast cancer cells with 200 μM OA induces an increase on MMP-9 secretion through a PKC, Src, and EGFR-dependent pathway, as revealed by gelatin zymography assays. Furthermore, microtubule network mediates MMP-9 secretion induced by OA. In contrast, OA does not induce an increase on MMP-9 secretion in MCF10A cells, whereas it does not induce MMP-9 secretion in MCF12A mammary non-tumorigenic epithelial cells. In addition, OA induces invasion through an EGFR, Gi/Go proteins, MMPs, PKC and Src-dependent pathway, but it is not able to promote invasion in non-invasive MCF-7 breast cancer cells. In summary, our findings demonstrate that OA promotes an increase on MMP-9 secretion and invasion through a PKC, Src, and EGFR-dependent pathway in breast cancer cells.

FGF-2 release from the lens capsule by MMP-2 maintains lens epithelial cell viability

The lens is an avascular tissue, separated from the aqueous and vitreous humors by its own extracellular matrix, the lens capsule. Here we demonstrate that the lens capsule is a source of essential survival factors for lens epithelial cells. Primary and immortalized lens epithelial cells survive in low levels of serum and are resistant to staurosporine-induced apoptosis when they remain in contact with the lens capsule. Physical contact with the capsule is required for maximal resistance to stress. The lens capsule is also a source of soluble factors including fibroblast growth factor 2 (FGF-2) and perlecan, an extracellular matrix component that enhances FGF-2 activity. Matrix metalloproteinase 2 (MMP-2) inhibition as well as MMP-2 pretreatment of lens capsules greatly reduced the protective effect of the lens capsule, although this could be largely reversed by the addition of either conditioned medium or recombinant FGF-2. These data suggest that FGF-2 release from the lens capsule by MMP-2 is essential to lens epithelial cell viability and survival.

Conjugated linoleic acid alters matrix metalloproteinases of metastatic mouse mammary tumor cells

Conjugated linoleic acid (CLA) is a group of linoleic acid derivatives that has been implicated in animal studies to reduce a number of components of mammary tumorigenesis. Previously, we showed that CLA could alter the latency and metastasis of the highly metastatic transplantable line 4526 mouse mammary tumor. Several possible mechanisms have been proposed for the actions of CLA, but here we assessed how CLA may act to alter the expression and activity of matrix-modifying proteins within tumors from line 4526. In vitro, highly metastatic mouse mammary tumor cells had significantly decreased invasiveness after treatment with CLA, an indication that matrix-modifying proteins may have been altered. Using these same highly metastatic cells, primary tumors were grown in mice of separate groups fed 0, 0.1, 0.5, and 1% CLA (wt:wt) and evaluated for their levels and activities of matrix-modifying enzymes, enzyme inhibitors, and enzyme activators. The addition of CLA to the diet increased steady-state levels of messenger RNA (mRNA) of the matrix metalloproteinases (MMP) -2 and -9 in primary tumors removed from mice. However, western analysis revealed that although relative levels of the proform of MMP-9 were consistent with the mRNA observations, MMP-2 proform levels were actually decreased by dietary CLA. The activity of MMP-2 was barely detectable, but gelatin zymography and an in vitro activity assay showed that MMP-9 activity was significantly decreased by CLA. The steady-state mRNA and protein levels of tissue inhibitors of metalloproteinase-1 (TIMP-1) and TIMP-2, natural inhibitors of MMP, were increased at higher dietary CLA levels relative to low or no CLA. Suppression of MMP activity, therefore, may be 1 pathway through which CLA reduces tumor invasion and spread.

Fibronectin type II (FnII)-like modules regulate gelatinase A activity

Gelatinase A, a member of the matrix metalloproteinase family, contains three fibronectin type II (FnII)-like modules that are inserted within its catalytic domain. These FnII modules, defined as exosites, play an essential role in targeting the enzyme to matrix macromolecules, a process which can down-regulate membrane-type metalloproteinase-driven progelatinase A activation. The exosite/substrate-directed gelatinase inhibitors has been proposed as an alternative approach to disappointing active site-directed inhibitors, to control gelatinase A activity. In preliminary experiments, we evidenced that long-chain unsaturated fatty acids could bind preferentially to the first FnII module of gelatinase A. This interaction inhibits the activity of this enzyme towards proteins (type I gelatin and collagen) and an octapeptide substrate, with K(i) in the micromolar range. Since gelatinase A-catalyzed matrix proteolysis might display a positive or negative influence (depending on the substrate cleaved), the design of exosite-specific compounds for noncatalytic targeting of gelatinase A would necessitate an extensive degradomic analysis.

Transmigration of human ovarian adenocarcinoma cells through endothelial extracellular matrix involves alphav integrins and the participation of MMP2

The growth of ovarian carcinoma is dependent upon their vascularistion, but the interaction of ovarian cancer cells with the endothelium and their invasion through an endothelial environment remain poorly understood at the molecular level. To investigate adhesive events underlying this process with focusing on the role of alphav integrins and MT1MMP-MMP2 proteinases, we used in vitro models of cocultures of human ovarian adenocarcinoma cell lines (IGROV1 and SKOV3) with human umbilical vein endothelial cells (HUVECs). Immunostaining of HUVECs revealed the network organisation of fibrillar fibronectin (Fn) and pericellular vitronectin (Vn). During coculture, IGROV1 and SKOV3 cells gain access to subendothelial basement membrane of HUVECs and dislocated endothelial Fn without affecting endothelial Vn. Transmigration assays revealed that tumour cells invade Vn and, with an higher efficiency, Fn. Our data also highlighted that ovarian carcinoma cells migrated through the Fn-rich HUVEC-ECM. The expression of MMP2 and MT1-MMP was revealed in tumour cells within an endothelial environment. Furthermore, we found that cell migration through the endothelial ECM was almost totally dependent on alphav integrin function, whereas beta1 integrins were not solicited. In addition, inhibitors of MMP2 activity (alone or combined with anti-alphav integrin MAb) or TSRI265 (which blocks MMP2-alphavbeta3 association) were found to impede this process. Finally, alphav integrins, MT1-MMP and MMP2 were found in ovarian carcinoma cells within the 3-dimensional architecture of intraperitoneal tumour nodes collected from nude mice xenografted with IGROV1 or SKOV3 cell lines or within human tumour tissues. alphav integrins therefore appear as essential to the migration properties of human ovarian carcinoma cells, especially in an endothelial environment, with MMP2 participating to this process.

Cytoskeletal rearrangement and signal transduction in TGF-beta1-stimulated mesangial cell collagen accumulation

TGF-beta1 has been implicated in glomerular extracellular matrix accumulation, although the precise cellular mechanism(s) by which this occurs is not fully understood. The authors have previously shown that the Smad signaling pathway is present and functional in human glomerular mesangial cells and plays a role in activating type I collagen gene expression. It also was determined that TGF-beta1 activates ERK mitogen-activated protein kinase in mesangial cells to enhance Smad activation and collagen expression. Here, it was shown that TGF-beta1 rapidly induces cytoskeletal rearrangement in human mesangial cells, stimulating smooth muscle alpha-actin detection in stress fibers and promoting focal adhesion complex assembly and redistribution. Disrupting the actin cytoskeleton with cytochalasin D (Cyto D) selectively decreased basal and TGF-beta1-induced cell-layer collagen I and IV accumulation. The balance of matrix metalloproteinases (MMP) and inhibitors was altered by Cyto D or TGF-beta1 alone, increasing MMP activity, increasing MMP-1 expression, and decreasing tissue inhibitor of matrix metalloproteinase-2 expression. Cyto D also decreased basal and TGF-beta1-stimulated alpha1(I) collagen mRNA but did not inhibit TGF-beta-stimulated alpha1(IV) mRNA expression. A similar decrease in alpha1(I) mRNA expression caused by the actin polymerization inhibitor latrunculin B was partially blocked by the addition of jasplakinolide, which promotes actin assembly. The Rho-family GTPase inhibitor C. difficile toxin B or the Rho-associated kinase inhibitor Y-27632 also blocked TGF-beta1-stimulated alpha1(I) mRNA expression. Cytoskeletal disruption reduced Smad2 phosphorylation but had little effect on mRNA stability, TGF-beta receptor number, or receptor affinity. Thus, TGF-beta1-mediated collagen I accumulation is associated with cytoskeletal rearrangement and Rho-GTPase signaling.

Improved gelatinase a selectivity by novel zinc binding groups containing galardin derivatives

The synthesis of several analogues of galardin, a MMP inhibitor, are presented with their in vitro inhibitory activity against MMP-1 and MMP-2. These compounds contain a distinct Zinc Binding Group (ZBG). Those having a 2-acylated-heterocycle as well as a 2-arylamide function do not exhibit a good inhibition/selectivity against the enzymes tested. On the contrary, those that are based on a hydrazide scaffold present potent selectivity for MMP-2 versus MMP-1.

Cytochalasin D disruption of actin filaments in 3T3 cells produces an anti-apoptotic response by activating gelatinase A extracellularly and initiating intracellular survival signals

Disruption of actin filaments affects multiple cell functions including motility, signal transduction and cell division, ultimately culminating in cell death. Although this is the usual sequence of events, we have made the interesting observation that disruption of actin filaments by the potent toxin cytochalasin D (Cyto D) causes one cell type, mouse mesangial cells (MMC), to undergo apoptosis, while in another cell type (NIH 3T3), it has the opposite effect, resulting in production of survival signals. The purpose of this study was to investigate the molecular basis for these observed differences. In the present communication, we demonstrate that exposure to Cyto D induces the pro-apoptotic pathways, p38 and stress-activated protein kinase (SAPK)/jun amino-terminal kinase (JNK), in both cell types. However, in 3T3, but not MMC, the extracellular signal regulated kinase (ERK) 1/2 pathway is protected from inhibition following treatment with Cyto D-leading to phosphorylation of Bclxi/Bcl 2-associated death promoter (BAD). Inhibition of Cyto D-induced secretion and activation of gelatinase A in 3T3 cells reverses the production of survival signals by Cyto-D. To investigate this effect further we employed CS-1 cells, a well-characterized melanoma cell line that lacks integrin beta3, and also does not secrete gelatinase A. Co-transfection of CS-1 cells with integrin beta3 and a gelatinase A transgene, which enables the cells to secrete constituitively active gelatinase A, enhances CS-1 cell survival signals. Together, our findings suggest that extracellularly activated gelatinase A, through interaction with integrin alphaVbeta3, elicits survival signals mediated through ERK 1/2 that override activation of p38 and SAPK/JNK stress pathways.

Involvement of fibronectin type II repeats in the efficient inhibition of gelatinases A and B by long-chain unsaturated fatty acids

The matrix metalloproteinases gelatinase A (MMP-2) and gelatinase B (MMP-9) are implicated in the physiological and pathological breakdown of several extracellular matrix proteins. In the present study, we show that long-chain fatty acids (e.g. oleic acid, elaidic acid, and cis- and trans-parinaric acids) inhibit gelatinase A as well as gelatinase B with K(i) values in the micromolar range but had only weak inhibitory effect on collagenase-1 (MMP-1), as assessed using synthetic or natural substrates. The inhibition of gelatinases depended on fatty acid chain length (with C18 > C16, C14, and C10), and the presence of unsaturations increased their inhibitory capacity on both types of gelatinase. Ex vivo experiments on human skin tissue sections have shown that micromolar concentrations of a long-chain unsaturated fatty acid (elaidic acid) protect collagen and elastin fibers against degradation by gelatinases A and B, respectively. In order to understand why gelatinases are more susceptible than collagenase-1 to inhibition by long-chain fatty acids, the possible role of the fibronectin-like domain (a domain unique to gelatinases) in binding inhibitory fatty acids was investigated. Affinity and kinetic studies with a recombinant fibronectin-like domain of gelatinase A and with a recombinant mutant of gelatinase A from which this domain had been deleted pointed to an interaction of long-chain fatty acids with the fibronectin-like domain of the protease. Surface plasmon resonance studies on the interaction of long-chain fatty acids with the three individual type II modules of the fibronectin-like domain of gelatinase A revealed that the first type II module is primarily responsible for binding these compounds.