Matrix metalloproteinases (MMPs) and interleukin 1 (IL-1) are implicated in inflammation and tissue destruction, where IL-1 is a potent stimulator of connective tissue cells to produce the extracellular matrix-degrading MMPs. Here, we report that IL-1␤, but not IL-1␣, is degraded by MMP-1 (interstitial collagenase), MMP-2 (gelatinase A), MMP-3 (stromelysin 1), and MMP-9 (gelatinase B). This degradation was effectively blocked by tissue inhibitor of metalloproteinases (TIMP)-1. When IL-1␤ was treated with MMPs it lost the ability to enhance the synthesis of prostaglandin E 2 and pro-MMP-3 in human fibroblasts. The primary cleavage site of IL-1␤ by MMP-2 was identified at the Glu 25 -Leu 26 bond. These results suggest that IL-1␤ stimulates connective tissue cells to produce MMPs, but activated MMPs in turn negatively regulate the activity of IL-1␤. Matrix metalloproteinases (MMPs),1 also called matrixins, degrade extracellular matrix macromolecules and play important roles in many biological processes such as morphogenesis, ovulation, embryo implantation, cell migration, tissue involution, angiogenesis, and wound healing (1-3). In excess, they participate in the destruction of the tissue associated with many connective tissue diseases such as arthritis, periodentitis, nephritis, and tissue ulcerations and with tumor cell invasion and metastasis (1-3). The importance of matrixins in both physiological and pathological catabolism of extracellular matrix macromolecules has been emphasized because little MMP activities can be detected in normal steady state tissue, but the synthesis of many MMPs is transcriptionally regulated by inflammatory cytokines, hormones, growth factors, and cellular transformation (1-3). For example, high levels of MMP-1 (interstitial collagenase, EC 3.4.24.7), MMP-3 (stromelysin 1, EC 3.4.24.17), and MMP-9 (gelatinase B, EC 3.4.24.35) are found in synovial tissues and fluids from patients with rheumatoid arthritis (4 -6). It is generally accepted that an elevated level of interleukin 1 (IL-1) is one of the key mediators that greatly enhances the biosynthesis and secretion of precursors of these MMPs (pro-MMPs) and prostaglandin E 2 from mesenchymal cells at inflammatory sites (1).IL-1 is secreted from activated macrophages and a variety of other cell types and elicits many other biological responses such as thymocyte proliferation, fever production, wound healing, and tissue resorption (see Ref. 7 for review). The promotion of wound healing and tissue degradation is considered to be in part due to the production of MMPs by cells stimulated with IL-1. The suppression of IL-1 activity is, therefore, thought to be an effective step to control inflammatory responses. In this regard, a large number of studies have focused on the regulation of IL-1 synthesis, processing of the IL-1 precursor, and the receptor antagonist (7). However, little is known about the catabolism of the mature form of IL-1.In this communication, we report that MMP-1, MMP-2 (gelatinase A, EC 3.4.24.24), MMP-3, and MMP-9 secre...

The mechanisms underlying cellular drug resistance have been extensively studied, but little is known about its regulation. We have previously reported that activating transcription factor 4 (ATF4) is upregulated in cisplatinresistant cells and plays a role in cisplatin resistance. Here, we find out a novel relationship between the circadian transcription factor Clock and drug resistance. Clock drives the periodical expression of many genes that regulate hormone release, cell division, sleep-awake cycle and tumor growth. We demonstrate that ATF4 is a direct target of Clock, and that Clock is overexpressed in cisplatin-resistant cells. Furthermore, Clock expression significantly correlates with cisplatin sensitivity, and that the downregulation of either Clock or ATF4 confers sensitivity of A549 cells to cisplatin and etoposide. Notably, ATF4-overexpressing cells show multidrug resistance and marked elevation of intracellular glutathione. The microarray study reveals that genes for glutathione metabolism are generally downregulated by the knockdown of ATF4 expression. These results suggest that the Clock and ATF4 transcription system might play an important role in multidrug resistance through glutathione-dependent redox system, and also indicate that physiological potentials of Clock-controlled redox system might be important to better understand the oxidative stress-associated disorders including cancer and systemic chronotherapy.

Aim: A growing body of evidence has shown that increased formation of oxidized molecules and reactive oxygen species within the vasculature (i.e., the extracellular space) plays a crucial role in the initiation and progression of atherosclerosis and in the formation of unstable plaques. Peroxiredoxin 4 (PRDX4) is the only known secretory member of the antioxidant PRDX family. However, the relationship between PRDX4 and susceptibility to atherosclerosis has remained unclear. Results: To define the role of PRDX4 in hyperlipidemia-induced atherosclerosis, we generated hPRDX4 transgenic (Tg) and apolipoprotein E (apoE) knockout mice (hPRDX4 +/+ /apoE -/ -). After feeding the mice a high-cholesterol diet, they showed fewer atheromatous plaques, less T-lymphocyte infiltration, lower levels of oxidative stress markers, less necrosis, a larger number of smooth muscle cells, and a larger amount of collagen, resulting in thickened fibrous cap formation and possible stable plaque phenotype as compared with apoE -/ -mice. We also detected greater suppression of apoptosis and decreased Bax expression in hPRDX4 +/+ /apoE -/ -mice than in apoE -/ -mice. Bone marrow transplantation from hPRDX4 +/+ donors to apoE -/ -mice confirmed the antiatherogenic aspects of PRDX4, revealing significantly suppressed atherosclerotic progression. Innovation: In this study, we demonstrated for the first time that PRDX4 suppressed the development of atherosclerosis in apoE -/ -mice fed a high-cholesterol diet. Conclusion: These data indicate that PRDX4 is an antiatherogenic factor and, by suppressing oxidative damage and apoptosis, that it may protect against the formation of vulnerable (unstable) plaques. Antioxid. Redox Signal. 17, 1362-1375.

One characteristic elements in the promoter of the matrix metalloproteinase 9 (MMP-9) gene is the d(CA) repeat. To investigate whether this element regulates the transcription of the MMP-9 gene and its enzymatic activities, we sequenced the promoter region isolated from esophageal carcinoma cell lines.

Cancer cells show constitutive upregulation of glycolysis, and the concentration of lactate thus produced correlates with prognosis. Here, we examined whether lactate concentration and lactate transporter expression are related to migration and invasion activity. We found that the expression of the monocarboxylate transporters MCT1 and MCT4, but not MCT5, in human lung cancer cell lines was significantly correlated with invasiveness. To clarify the effects of MCT1 and MCT4 expression on invasion, we performed migration and invasion assays after transfection with siRNA specific for MCT1 or MCT4. Knockdown of MCT1 or MCT4 did not influence cell migration but reduced invasion; this was also observed for knockdown of the lactate transporter-associated protein basigin. We also demonstrated that both expression and activity of MMP9 and MMP2 were not correlated with invasion activity and not regulated by MCT1, MCT4 and basigin. Furthermore, the addition of lactate did not increase migration and invasion activity, but low concentration of 4,4¢-diisothiocyanatostilbene-2,2¢-disulphonic acid (DIDS), a general anion channel blocker, as well as other MCT inhibitors quercetin and simvastatin, inhibited cell invasion without influencing migration activity and the cellular expression of MCT1 and MCT4. This is the first report suggesting that lactate transporters are involved in human cancer cell invasiveness. As such, these proteins may be promising targets for the prevention of cancer invasion and metastasis. (Cancer Sci 2011; 102: 1007-1013 M onocarboxylates, such as lactate and pyruvate, play a central role in cellular metabolism and metabolic communication between tissues.(1) In cancer cells, a steady source of metabolic energy is required to continue the uncontrolled growth and proliferation of these cells.(2) Most cancer cells rely on a high rate of aerobic glycolysis, a phenomenon termed ''the Warburg effect'', to obtain sufficient ATP in a hypoxic microenvironment.(3) As a result of the Warburg effect, lactate is abundantly synthesized from pyruvate, (4) but lactic acid induces cellular acidosis, which triggers apoptosis. To avoid apoptosis, cancer cells must transport the lactate out of the cell. On the other hand, lactate is not just a waste product: it was recently identified as a major energy fuel in tumors.(4) Lactate is transported by monocarboxylate anion transporters (MCT; also called the solute carrier family 16 [SLC16]).(1) It is known that MCT4 (SLC16A3) transports lactate out of the cell (5) and MCT1 (SLC16A1) regulates the entry of lactate into tumor cells. (4) Migration and invasion are two of the most important aspects of the malignant cancer phenotype; if they could be inhibited, the cancer prognosis would improve. Hypoxia and acidosis create a nurturing environment for tumor progression and the evolution of metastases, and invasiveness is abetted by acidosis, the result of shifting to an anaerobic glycolytic metabolism.(6) Basigin (BSG; also called EMMPRIN and CD147) is a multifunctional glycoprotein ...