Interferon-gamma differentially regulates monocyte matrix metalloproteinase-1 and -9 through tumor necrosis factor-alpha and caspase 8

Tumor necrosis factor-alpha (TNFalpha) and granulocyte macrophage colony-stimulating factor (GM-CSF) individually enhance monocyte matrix metalloproteinase-9 (MMP-9) but induce MMP-1 only when added in combination. Because interferon-gamma (IFNgamma) is also found at inflammatory sites, we determined its effect on monocyte MMPs in the presence or absence of TNFalpha and GM-CSF. IFNgamma alone did not stimulate monocyte MMP-9 or MMP-1; however, in the presence of GM-CSF it induced MMP-1 and enhanced MMP-1 stimulated by GM-CSF and TNFalpha. IFNgamma induced MMP-1 in the presence of GM-CSF through the stimulation of TNFalpha production through a mechanism involving both p38 and ERK1/2 MAPKs, in which GM-CSF stimulated ERK1/2 whereas IFNgamma activated p38. In support of this conclusion TNFalpha neutralizing antibody and antibodies against TNF receptor I and -II blocked the induction of MMP-1 by GM-CSF and IFNgamma. In contrast to its effects on MMP-1, IFNgamma inhibited TNFalpha-induced MMP-9 through a caspase 8-dependent pathway as demonstrated by the restoration of MMP-9 with caspase 8 inhibitors. Moreover, the phosphorylation of STAT1 by IFNgamma was blocked by an inhibitor of caspase 8, indicating that STAT1 had a suppressive effect on MMP-9. Caspase 8-mediated phosphorylation of STAT1 through p38 MAPK as shown by the inhibition of IFNgamma-induced phosphorylation of p38 by caspase 8 inhibitors. Activation of caspase 8 by IFNgamma did not result in increased apoptosis. Thus IFNgamma in the presence of GM-CSF and/or TNFalpha differentially regulates monocyte MMPs through induction of TNFalpha and a novel mechanism involving caspase 8 that is independent of apoptosis.     

Interferons inhibit tumor necrosis factor-alpha-mediated matrix metalloproteinase-9 activation via interferon regulatory factor-1 binding competition with NF-kappa B

Enhanced expression of matrix metalloproteinase-9 (MMP-9) correlates with invasion during tumor progression. Interferons (IFNs) inhibit MMP-9 activation in response to tumor necrosis factor-alpha (TNF-alpha), and the latter activates the MMP-9 gene through NF-kappaB. Understanding the molecular basis for MMP-9 inhibition may provide tools to control cell invasion. The data reported here show the critical role of interferon regulatory factor-1 (IRF1) in the inhibition of MMP-9. (i) IFN treatment suppresses TNF-alpha-induced MMP-9 reporter activity in STAT1(+/+) cells but not in STAT1(-/-) cells. (ii) IRF1 transfection blocks TNF-alpha-mediated MMP-9 activation. (iii) IFNs phosphorylate STAT1 and induce IRF1 but do not affect Ikappa-B degradation nor NF-kappaB nuclear translocation. (iv) Nuclear NF-kappaB (p50/p65) and IRF1, but not STAT1, bind to the MMP-9 promoter region containing an IFN-responsive-like element overlapping the NF-kappaB-binding site. (v) Recombinant IRF1, although unable to bind to an NF-kappaB consensus sequence, competes with NF-kappaB proteins for binding to the MMP-9 promoter. (vi) Conversely recombinant p50/p65 proteins reduce IRF1-DNA binding. (vii) In cells cotransfected with IRF1 and/or p65 expression vectors, an excess of IRF1 reduces MMP-9 reporter activity, whereas an excess of p65 blocks the inhibitory effect of IFN-gamma. Thus, in contrast to the known synergism between IRF1 and NF-kappaB, our data identify a novel role for IRF1 as a competitive inhibitor of NF-kappaB binding to the particular MMP-9 promoter context.     

Epidermal growth factor and transforming growth factor-beta1 enhance HK-2 cell migration through a synergistic increase of matrix metalloproteinase and sustained activation of ERK signaling pathway

Epidermal growth factor (EGF) and transforming growth factor-beta1 (TGF-beta1), upregulated in renal diseases, have a combinational effect on epithelial-mesenchymal transformation (EMT) of renal proximal tubular cells. The aim of this study was to examine the mechanism regarding the combinational effect of EGF and TGF-beta1 on cell migration following EMT. The results demonstrated that EGF (10 ng/ml) and TGF-beta1 (3 ng/ml) synergistically increased cell migration, accompanied by an increase in matrix metalloproteinase-9 (MMP-9) gene expression, production and activity. Inhibition of MMP-9 production and activity by an MMP-2/MMP-9-specific inhibitor blocked the synergistic effect of EGF and TGF-beta1 on cell migration. The kinetic profile of extracellular signal-regulated kinase (ERK) signals demonstrated that ERK1/2 activation was rapidly and strongly induced by EGF but delayed and less marked by TGF-beta1 stimulation. In contrast, co-administration of EGF and TGF-beta1 caused an early pronounced and persistent ERK1/2 activation. Inhibition of the ERK1/2 activity by PD98059 abrogated the synergistic effect of EGF and TGF-beta1 on cell migration, MMP-9 production and activity, indicating that EGF and TGF-beta1 converged at the ERK signaling pathway to mediate cell migration. This study demonstrates that EGF and TGF-beta1 synergistically stimulate proximal tubular cell migration through the increased MMP-9 function and enhanced ERK1/2 activation.     

Resveratrol inhibits heregulin-beta1-mediated matrix metalloproteinase-9 expression and cell invasion in human breast cancer cells

The growth factor heregulin-β1 (HRG-β1), which is expressed in breast cancer, activates the HER-2 signaling pathway through induction of heterodimeric complexes of HER-2 with HER-3 or HER-4. It has been shown in many studies that HRG-β1 induces the tumorigenicity and metastasis of breast cancer cells. Matrix metalloproteinase (MMP) 9 is a key enzyme in the degradation of extracellular matrices, and its expression may be dysregulated in breast cancer invasion and metastasis. Resveratrol, a major component in grape, exhibited potential anticarcinogenic activities in both in vitro and in vivo studies. However, the inhibitory effect of resveratrol on HER-2-mediated expression of MMP-9 has not been demonstrated yet.

In the present study, we investigated the anti-invasive mechanism of resveratrol in human breast cancer cells. Human breast cancer MCF-7 cells were exposed to resveratrol (2, 5 and 10 μM). The expression activity of MMP-9 was measured by zymogram analysis. Phosphorylated levels of HER-2 and mitogen-activated protein kinase (MAPK)/ERK were measured by Western blot analysis. Total actin was used as internal control for protein expression. HRG-β1 induced the phosphorylation of HER-2/neu receptor and MMP-9 expression in human breast cancer MCF-7 cells. Resveratrol significantly inhibited HRG-β1-mediated MMP-9 expression in human breast cancer cells. MEK inhibitor induced a marked reduction in MMP-9 expression, and it suggested that ERK1/2 cascade could play an important role in HRG-β1-mediated MMP-9 expression. Furthermore, resveratrol significantly suppressed HRG-β1-mediated phosphorylation of ERK1/2 and invasion of breast cancer cells. However, resveratrol had negligible effects on either HRG-β1-mediated phosphorylation of HER-2 receptor or expression of the tissue inhibitor of MMP, tissue inhibitor metalloproteinase protein 1.

Taken together, our results suggest that resveratrol inhibited MMP-9 expression in human breast cancer cells. The inhibitory effects of resveratrol on MMP-9 expression and invasion of breast cancer cells are, in part, associated with the down-regulation of the MAPK/ERK signaling pathway.     

Identification and partial characterization of FRAG-6, a novel interferon-stimulated gene that is expressed in an IRF-1-INDEPENDENT manner.

In order to identify new interferon-stimulated genes that could help in the better understanding of the mechanism of action of interferons (IFNs), we decided to compare, by differential display RT-PCR (DDRT-PCR), the pattern of gene expression between IFN-alpha treated and untreated mouse embryonic fibroblasts (MEFs). Here we describe the initial characterization of a new cDNA fragment, named FRAG-6, that is expressed only upon IFN stimulation. The IFN-induced expression of this new gene can be observed in both wild-type and IRF-1-deficient MEF. FRAG-6 cDNA hybridizes with an mRNA of 6-9 kb that is induced by IFNs in a time-dependent manner. Analysis of the cloned nucleotide sequence revealed a 174 amino acid (aa) open reading frame (ORF) contained within the 576 bp. No significant homology with known nucleotide or protein sequences was observed. FRAG-6 is induced in vitro upon treatment of wild type or IRF-1-null cells with IFN-alpha or -gamma, but not with TNF or IL-1. Treatment of mice with imiquimod, a potent inducer of IFN, led to induced expression of FRAG-6 mRNA in various organs from wild type or IRF-1-deficient mice, but not from STAT-1 or type I IFN receptor deficient animals. Our results demonstrate that FRAG-6 mRNA induction by interferons is IRF-1-independent and it is likely to be activated by the JAK/STAT pathway. Further characterization of FRAG-6 will help us in the understanding of the mechanism of action of IFNs.     

MMP-14 mediated MMP-9 expression is involved in TGF-beta1-induced keratinocyte migration

The importance of expression of matrix metalloproteinase (MMP) in keratinocyte migration is well established, but its role remains unclear. Here we investigated the function of MMP-14 in TGF-beta1-induced keratinocyte migration. TGF-beta1 stimulated cell migration and the expression of MMP-2, -9 in HaCaT human keratinocyte cells. When we lowered MMP-14 mRNA with siRNA, cell migration, and MMP-9 expression decreased. Furthermore, the MMP-14 siRNA also reduced activation of JNK in response to TGF-beta1, and a JNK-specific inhibitor decreased both cell migration and MMP-9 expression. Taken together, these results suggest that TGF-beta1-induced HaCaT cell migration is mediated by MMP-14, which regulates MMP-9 expression via JNK signaling.     

Transforming growth factor-beta1 modulates matrix metalloproteinase-9 production through the Ras/MAPK signaling pathway in transformed keratinocytes

Mouse transformed keratinocytes cultured in the presence of transforming growth factor-beta1 (TGF-beta1) acquire a set of morphological and functional properties giving rise to a more motile phenotype that expresses mesenchymal markers. In this work, we present evidence showing that TGF-beta1 stimulates cellular production of MMP-9 (Gelatinase B), a metalloproteinase that plays an important role in tumoral invasion. Our results demonstrate that TGF-beta1stimulates MMP-9 production and MMP-9 promoter activity in a process that depends of the activation of the Ras-ERK1,2 MAP kinase pathway. The latter was demonstrated by cellular transfection of TGF-beta1-sensitive cells with a RasN17 mutant gene, using PD 098059, a MEK 1,2 inhibitor, and treating cells with anti-sense oligodeoxinucleotides. The enhanced MMP-9 production proved to be an important factor in the acquisition of migratory and invasive properties as shown by the use of a specific inhibitor of MMP-9 (GM6001) that inhibits the TGF-beta1-stimulated invasive and migratory properties of these transformed keratinocytes.     

Regulation of human monocyte proMMP-9 production by fetuin, an endogenous TGF-beta antagonist

Members of the matrix metalloproteinase family of enzymes degrade specific components of the extracellular matrix. MMP-9 is a type IV/V collagenase necessary for normal osteogenesis and is increased in inflammatory and neoplastic conditions. In such destructive diseases as emphysema and arthritis, and in epithelial cancers, MMP-9 is produced by cells of the monocyte lineage. Fetuin, a prominent serum glycoprotein, binds to and inactivates TGF-beta family members and through this mechanism regulates osteogenesis (Binkert et al., 1999, J Biol Chem 274:28514-28520.). We studied the effects of TGF-beta1 and fetuin on proMMP-9 release by the human monocyte line THP-1. Exogenous TGF-beta1 stimulated proMMP-9 release by THP-1 cells, with half-maximal stimulation at approximately 0.01 ng/ml TGF-beta1. Human fetuin (0.5-2 microM) partially inhibited this stimulation. Human fetuin alone stimulated THP-1 monocyte proMMP-9 release, with half maximal stimulation at approximately 0.25 microM fetuin. Neutralizing antibody specific for TGF-beta1 also stimulated proMMP-9 release, suggesting that endogenously-derived TGF-beta1 has an inhibitory effect. In freshly isolated human peripheral blood monocytes, fetuin stimulated proMMP-9 release with a dose-response curve similar to that observed in THP-1 cells. Human fetuin also activated proMMP-9 present in THP-1 conditioned medium. Taken together, these data suggest that under physiological conditions, fetuin facilitates matrix degradation by monocyte-derived MMP-9, both by opposing the autocrine inhibitory effect of endogenous TGF-beta1 on proMMP-9 release, and by activating proMMP-9 in the pericellular milieu. Conversely, fetuin may limit the stimulation of monocyte proMMP-9 release by high levels of exogenous TGF-beta1. Such modulation could prove important under pathological conditions where TGF-beta1 derived from paracrine sources is abundant, such as in epithelial malignancies.