Matrix metalloproteinases (MMPs) are essential for proper extracellular matrix remodeling. We previously found that a membrane-anchored glycoprotein, RECK, negatively regulates MMP-9 and inhibits tumor invasion and metastasis. Here we show that RECK regulates two other MMPs, MMP-2 and MT1-MMP, known to be involved in cancer progression, that mice lacking a functional RECK gene die around E10.5 with defects in collagen fibrils, the basal lamina, and vascular development, and that this phenotype is partially suppressed by MMP-2 null mutation. Also, vascular sprouting is dramatically suppressed in tumors derived from RECK-expressing fibrosarcoma cells grown in nude mice. These results support a role for RECK in the regulation of MMP-2 in vivo and implicate RECK downregulation in tumor angiogenesis.

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Background Cardiovascular disease is the leading cause of death among diabetics. Vitamin D deficiency is associated with increased risk of cardiovascular disease in this population. To determine the mechanism by which vitamin D deficiency mediates accelerated cardiovascular disease in patients with diabetes, we investigated the effects of active vitamin D on macrophage cholesterol deposition. Methods and Results We obtained macrophages from 76 obese, diabetic, hypertensive patients with vitamin D deficiency (25-hydroxyvitamin D < 80 nmol/L)(group A) and four control groups: obese, diabetic, hypertensive patients with normal vitamin D (group B, n=15), obese, non-diabetic, hypertensive patients with vitamin D deficiency (group C, n=25), and non-obese, non-diabetic, non-hypertensive patients with vitamin D deficiency (group D, n=10) or sufficiency (group E, n=10). The same patient’s macrophages from all groups were cultured in vitamin D-deficient or 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) supplemented media and exposed to modified low-density lipoprotein cholesterol. 1,25(OH)2D3 suppressed foam cell formation by reducing acetylated or oxidized low-density lipoprotein cholesterol uptake in diabetics only. Conversely, deletion of the vitamin D receptor in macrophages from diabetic patients accelerated foam-cell formation induced by modified LDL. 1,25(OH)2D3 downregulation of c-Jun N-terminal kinase activation reduced PPARγ expression, suppressed CD36 expression, and prevented oxLDL-derived cholesterol uptake. In addition, 1,25(OH)2D3 suppression of macrophage endoplasmic reticulum stress improved insulin signaling, downregulated SR-A1expression, and prevented oxLDL and AcLDL-derived cholesterol uptake. Conclusion These results identify reduced vitamin D receptor signaling as a potential mechanism underlying increased foam-cell formation and accelerated cardiovascular disease in diabetics.

Background:The interplay of lipid signaling with macrophage phenotype is critical for vascular disease progression. Results: ER stress links scavenger receptor signaling to macrophage phenotype and foam cell formation through a JNK-and PPAR␥-dependent pathway. Conclusion: ER stress is a functional switch controlling macrophage phenotype and cellular cholesterol content. Significance: Suppression of ER stress is a potential therapeutic target to reduce atherosclerosis progression.

The tissue inhibitors of metalloproteinases (TIMPs) regulate matrix metalloproteinase activity required for cell migration/invasion associated with cancer progression and angiogenesis. TIMPs also modulate cell proliferation in vitro and angiogenesis in vivo independent of their matrix metalloproteinase inhibitory activity. Here, we show that TIMP-2 mediates G 1 growth arrest in human endothelial cells through de novo synthesis of the cyclin-dependent kinase inhibitor p27 Kip1 . TIMP-2-mediated inhibition of Cdk4 and Cdk2 activity is associated with increased binding of p27Kip1 to these complexes in vivo. Protein-tyrosine phosphatase inhibitors or expression of a dominant negative Shp-1 mutant ablates TIMP-2 induction of p27 Kip1 . Finally, angiogenic responses to fibroblast growth factor-2 and vascular endothelial growth factor-A in "motheaten viable" Shp-1-deficient mice are resistant to TIMP-2 inhibition, demonstrating that Shp-1 is an important negative regulator of angiogenesis in vivo.Angiogenesis, the formation of new blood vessels from pre-existing vessels, accompanies a variety of pathologic responses in the adult, such as wound healing, tumor growth, cancer progression, and many chronic inflammatory diseases (1). Angiogenesis requires the dissolution of existing extracellular matrix and formation of new extracellular matrix, in particular the subendothelial basement membrane (2). The matrix metalloproteinases (MMPs) 2 have been demonstrated to play a pivotal role in angiogenesis through altering biological functions of extracellular matrix macromolecules by selectively degrading and/or releasing matrix-or membrane-anchored growth factors (3). Endogenous protease inhibitors, such as the tissue inhibitors of metalloproteinases (TIMPs), regulate the activities of these proteinases. TIMPs can suppress cell proliferation and invasion and reduce metastasis formation through inhibition of MMP activity and prevention of extracellular matrix turnover (4). However, recent studies suggest that TIMPs also directly modulate cell growth and migration via MMP-independent mechanisms (5-11).TIMPs 1-3 all inhibit angiogenesis; however, the mechanisms of these effects appear to be specific for each member of the TIMP family. TIMP-1 blocks tumor-associated angiogenesis via a mechanism involving inhibition of MMP-dependent endothelial cell migration (5, 12). However, a recent report suggests that TIMP-1 may also inhibit endothelial cell migration by an MMP-independent mechanism as well (13). In contrast, TIMP-3 prevents vascular endothelial growth factor-A (VEGF-A)-induced angiogenesis by direct antagonism of binding of this growth factor to its cognate receptor, . Previous studies have demonstrated that TIMP-2 inhibits the proliferation of endothelial cells, fibroblasts, and carcinoma cell lines in response to stimulation with mitogenic growth factors such as fibroblast growth factor-2 (FGF-2), platelet-derived growth factor (PDGF), or epidermal growth factor (EGF) (6, 9, 10). TIMP-2 binds to the surface of human micro...