Eicosapentaenoic acid inhibits TNF-alpha-induced matrix metalloproteinase-9 expression in human keratinocytes, HaCaT cells

Eicosapentaenoic acid (EPA) is an omega-3 (ω-3) polyunsaturated fatty acid (PUFA), which has anti-inflammatory and anti-cancer properties. Some reports have demonstrated that EPA inhibits NF-κB activation induced by tumor necrosis factor (TNF)-α or lipopolysaccharide (LPS) in various cells. However, its detailed mode of action is unclear. In this report, we investigated whether EPA inhibits the expression of TNF-α-induced matrix metalloproteinases (MMP)-9 in human immortalized keratinocytes (HaCaT). TNF-α induced MMP-9 expression by NF-κB-dependent pathway. Pretreatment of EPA inhibited TNF-α-induced MMP-9 expression and p65 phosphorylation. However, EPA could not affect IκB-α phosphorylation, nuclear translocation of p65, and DNA binding activity of NF-κB. EPA inhibited TNF-α-induced p65 phosphorylation through p38 and Akt inhibition and this inhibition was IKKα-dependent event. Taken together, we demonstrate that EPA inhibits TNF-α-induced MMP-9 expression through inhibition of p38 and Akt activation.     

Curcumin suppresses phorbol ester-induced matrix metalloproteinase-9 expression by inhibiting the PKC to MAPK signaling pathways in human astroglioma cells

The aberrant expression of matrix metalloproteinase-9 (MMP-9) is implicated in the invasion and angiogenesis process of brain tumor. This study has investigated the effects of curcumin on MMP-9 expression in human astroglioma cell lines. Curcumin significantly inhibited the MMP-9 enzymatic activity and protein expression that was induced by PMA. The inhibitory effect of curcumin on MMP-9 expression correlates with the decreased MMP-9 mRNA level and the suppression of MMP-9 promoter activity. The curcumin-mediated inhibition of MMP-9 gene expression appears to occur via NF-kappaB and AP-1 because their DNA binding activities were suppressed by curcumin. Furthermore, curcumin strongly repressed the PMA-induced phosphorylation of ERK, JNK, and p38 MAP kinase, which were dependent on the PKC pathway. Therefore, the inhibition of MMP-9 expression by curcumin might have therapeutic potential for controlling the growth and invasiveness of brain tumor.     

Plaque oxysterols induce unbalanced up-regulation of matrix metalloproteinase-9 in macrophagic cells through redox-sensitive signaling pathways: Implications regarding the vulnerability of atherosclerotic lesions

An imbalance in the matrix metalloproteinases/tissue inhibitors of metalloproteinases (MMPs/TIMPs) contributes to atherosclerotic plaque destabilization and rupture. Here we determined whether oxysterols accumulating in advanced atherosclerotic lesions play a role in plaque destabilization. In human promonocytic U937 cells, we investigated the effects of an oxysterol mixture of composition similar to that in advanced human carotid plaques on the expression and synthesis of MMP-9 and its endogenous inhibitors TIMP-1 and TIMP-2. A marked increment of MMP-9 gene expression, but not of its inhibitors, was observed by real-time RT-PCR; MMP-9 gelatinolytic activity was also found increased by gel zymography. Consistently, a net increment of MMP-9 protein level was also observed by immunoblotting. Using antioxidants or specific inhibitors or siRNAs, we demonstrated that the oxysterol mixture induces MMP-9 expression through: (i) overproduction of reactive oxygen species, probably by NADPH-oxidase and mitochondria; (ii) up-regulation of mitogen-activated protein kinase signaling pathways via protein kinase C; and (iii) up-regulation of activator protein-1- and nuclear factor-κB-DNA binding. These results suggest, for the first time, that oxysterols accumulating in advanced atherosclerotic lesions significantly contribute to plaque vulnerability by promoting MMP-9/TIMP-1/2 imbalance in phagocytic cells.     

Suppression of tumor cell invasiveness by hydrolyzable tannins (plant polyphenols) via the inhibition of matrix metalloproteinase-2/-9 activity

Elevated expression of matrix metalloproteinases (MMPs), especially that of MMP-2 and MMP-9, is associated with increased metastatic potential in many tumor cells. Recently, green tea polyphenol epigallocatechin-3-O-gallate (EGCG) has been shown to inhibit the MMP-2/-9 activity as well as the invasiveness of tumor cells. In this study, we have examined the inhibitory effect of hydrolyzable tannins (plant polyphenols) on the tumor cell invasion. Our results demonstrate that beta-d-glucose whose hydroxy groups are substituted entirely with galloyl group and further some of them are cross-linked to form hexahydroxydiphenoyl group, for example, suppresses the invasiveness of tumor cells much more potently than EGCG via direct inhibition of the MMP-2/-9 activity. Among those examined, 1,2,4-tri-O-galloyl-3,6-hexahydroxydiphenoyl-beta-d-glucose (punicafolin) inhibits the invasion of HT1080 fibrosarcoma cells most potently. These hydrolyzable tannins would provide new leads for the development of potent inhibitors against tumor metastasis.     

Artemether Combined with shRNA Interference of Vascular Cell Adhesion Molecule-1 Significantly Inhibited the Malignant Biological Behavior of Human Glioma Cells

Artemether is the derivative extracted from Chinese traditional herb and originally used for malaria. Artemether also has potential therapeutic effects against tumors. Vascular cell adhesion molecule-1 (VCAM-1) is an important cell surface adhesion molecule associated with malignancy of gliomas. In this work, we investigated the role and mechanism of artemether combined with shRNA interference of VCAM-1 (shRNA-VCAM-1) on the migration, invasion and apoptosis of glioma cells. U87 human glioma cells were treated with artemether at various concentrations and shRNA interfering technology was employed to silence the expression of VCAM-1. Cell viability, migration, invasiveness and apoptosis were assessed with MTT, wound healing, Transwell and Annexin V-FITC/PI staining. The expression of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and phosphorylated Akt (p-Akt) was checked by Western blot assay. Results showed that artemether and shRNA-VCAM-1 not only significantly inhibited the migration, invasiveness and expression of MMP-2/9 and p-Akt, but also promoted the apoptosis of U87 cells. Combined treatment of both displayed the maximum inhibitory effects on the malignant biological behavior of glioma cells. Our work revealed the potential therapeutic effects of artemether and antiVCAM-1 in the treatments of gliomas.     

Toll-like receptor 9 ligands enhance mesenchymal stem cell invasion and expression of matrix metalloprotease-13

Human mesenchymal stem cells (hMSCs) are multipotent cells that are found in the bone marrow. Inflammation and tissue damage mobilize MSCs and induce their migration towards the damaged site through mechanisms that are not well defined. Toll-like receptor-9 (TLR9) is a cellular receptor for microbial and vertebrate DNA. Stimulation of TLR9 induces inflammatory and invasive responses in TLR9-expressing cells. We studied here the expression of TLR9 in human MSCs and the effects of synthetic TLR9-agonists on their invasion. Constitutive expression of TLR9 was detected in human MSCs but the expression was suppressed when MSCs were induced to differentiate into osteoblasts. Using standard invasion assays and a novel organotypic culture model based on human myoma tissue, we discovered that stimulation with the TLR9 agonistic, CpG oligonucleotides increased the invasion capacity of undifferentiated MSCs. Simultaneously, an increase in MMP-13 synthesis and activity was detected in the CpG-activated MSCs. Addition of anti-MMP-13 antibody significantly diminished the CpG-induced hMSC invasion. We conclude that treatment with TLR9-ligands increases MSC invasiveness, and this process is at least partially MMP-13-mediated.     

Chlorotoxin inhibits glioma cell invasion via matrix metalloproteinase-2

Primary brain tumors (gliomas) have the unusual ability to diffusely infiltrate the normal brain thereby evading surgical treatment. Chlorotoxin is a scorpion toxin that specifically binds to the surface of glioma cells and impairs their ability to invade. Using a recombinant His-Cltx we isolated and identified the principal Cltx receptor on the surface of glioma cells as matrix metalloproteinase-2 (MMP-2). MMP-2 is specifically up-regulated in gliomas and related cancers, but is not normally expressed in brain. We demonstrate that Cltx specifically and selectively interacts with MMP-2 isoforms, but not with MMP-1, -3, and -9, which are also expressed in malignant glioma cells. Importantly, we show that the anti-invasive effect of Cltx on glioma cells can be explained by its interactions with MMP-2. Cltx exerts a dual effect on MMP-2: it inhibits the enzymatic activity of MMP-2 and causes a reduction in the surface expression of MMP-2. These findings suggest that Cltx is a specific MMP-2 inhibitor with significant therapeutic potential for gliomas and other diseases that invoke the activity of MMP-2.     

An absolute role of the PKC-dependent NF-kappaB activation for induction of MMP-9 in hepatocellular carcinoma cells

Matrix metalloproteinases (MMPs) play an important role in inflammation, tumor cell invasion, and metastasis. We found that phorbol-12-myristate-13-acetate (PMA)-stimulated invasion of the hepatocellular carcinoma (HCC) SNU-387 and SNU-398 cells and that PMA induced the secretion of MMP-9 in the cells, but did not induce the secretion of MMP-2. The PMA-induced MMP-9 secretion was abolished by treatment of a pan-protein kinase C (PKC) inhibitor, GF109203X, and an inhibitor of NF-kappaB activation, sulfasalazine, and partly inhibited by treatment of inhibitors of ERK pathway, PD98059 and U0126. In addition, the PMA-stimulated activation of the MMP-9 promoter was completely inhibited by a mutation of the NF-kappaB site within the MMP-9 promoter, but not completely by mutations of two AP-1 sites. Moreover, the MMP-9 induction by HGF and TNF-alpha was also completely inhibited by GF109203X and sulfasalazine, but not by PD98059 and U0126. These data demonstrate that the PKC-dependent NF-kappaB activation is absolute for MMP-9 induction and that the PKC-dependent ERK activation devotes to increase the expression level of MMP-9, in HCC cells.     

Induced expression of MMP-9 in C6 glioma cells is inhibited by PDGF via a PI 3-kinase-dependent pathway

The involvement of phosphatidylinositol 3 (PI 3)-kinase in the signalling pathways leading to MMP-9 expression in glioma cells remains unclear. Here, we report that PI 3-kinase inhibits MMP-9 expression induced by either IL-1 or TNF-alpha in rat C6 glioma cells. Using zymography and semi-quantitative RT-PCR analysis, we showed that treatment of C6 cells with wortmannin, an inhibitor of PI 3-kinase activity, potentiated the expression of MMP-9 induced by both cytokines. In contrast, platelet-derived growth factor (PDGF), an inducer of PI 3-kinase activity in C6 cells, inhibited IL-1- or TNF-alpha-induced MMP-9 secretion. Accordingly, this inhibition by PDGF was prevented by wortmannin. Furthermore, stable C6 clones over-expressing the dominant-negative form the regulatory subunit of PI 3-kinase potentiated the expression of MMP-9 induced by IL-1 or TNF-alpha. Taken together, these results suggest that PI 3-kinase may act as a negative regulator of MMP-9 expression in C6 glioma cells.     

Activation of toll-like receptor-9 induces matrix metalloproteinase-9 expression through Akt and tumor necrosis factor-alpha signaling

CpG oligodeoxunucleotide (ODN) plays an important role in immune cell function. The present study examined whether temporal control of toll-like receptor (TLR)-9 by CpG ODN can regulate the expression of matrix metalloproteinase-9 (MMP-9). CpG ODN induced the release of tumor necrosis factor (TNF)-alpha and the expression of TNF receptor (TNFR)-II, but not of TNFR-I, in a time-dependent manner and stimulated significant, though delayed, MMP-9 expression. The endosomal acidification inhibitors, chloroquine or bafilomycin A, inhibited CpG ODN-induced TNF-alpha, TNFR-II, and MMP-9 expression. CpG ODN induced the phosphorylation of Akt, and the inhibition of Akt by LY294002 suppressed CpG ODN-induced TNF-alpha, TNFR-II, and MMP-9 expressions. Moreover, neutralizing TNF-alpha antibody significantly suppressed CpG ODN-induced MMP-9 expression, suggesting the involvement of TNF-alpha. These observations suggest that CpG ODN may play important roles in macrophage activation by regulating the expression of MMP-9 via a TLR-9/Akt/TNF-alpha-dependent signaling pathway.