Runx3/Pebp2alphaC null mouse gastric mucosa exhibits hyperplasias due to stimulated proliferation and suppressed apoptosis in epithelial cells, and the cells are resistant to growth-inhibitory and apoptosis-inducing action of TGF-beta, indicating that Runx3 is a major growth regulator of gastric epithelial cells. Between 45% and 60% of human gastric cancer cells do not significantly express RUNX3 due to hemizygous deletion and hypermethylation of the RUNX3 promoter region. Tumorigenicity of human gastric cancer cell lines in nude mice was inversely related to their level of RUNX3 expression, and a mutation (R122C) occurring within the conserved Runt domain abolished the tumor-suppressive effect of RUNX3, suggesting that a lack of RUNX3 function is causally related to the genesis and progression of human gastric cancer.

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Loss of RUNX3 expression is suggested to be causally related to gastric cancer as 45% to 60% of gastric cancers do not express RUNX3 mainly due to hypermethylation of the RUNX3 promoter. Here, we examined for other defects in the properties of RUNX3 in gastric cancers that express RUNX3. Ninety-seven gastric cancer tumor specimens and 21 gastric cancer cell lines were examined by immunohistochemistry using novel anti-RUNX3 monoclonal antibodies. In normal gastric mucosa, RUNX3 was expressed most strongly in the nuclei of chief cells as well as in surface epithelial cells. In chief cells, a significant portion of the protein was also found in the cytoplasm. RUNX3 was not detectable in 43 of 97 (44%) cases of gastric cancers tested and a further 38% showed exclusive cytoplasmic localization, whereas only 18% showed nuclear localization. Evidence is presented suggesting that transforming growth factor-B is an inducer of nuclear translocation of RUNX3, and RUNX3 in the cytoplasm of cancer cells is inactive as a tumor suppressor. RUNX3 was found to be inactive in 82% of gastric cancers through either gene silencing or protein mislocalization to the cytoplasm. In addition to the deregulation of mechanisms controlling gene expression, there would also seem to be at least one other mechanism controlling nuclear translocation of RUNX3 that is impaired frequently in gastric cancer. (Cancer Res 2005; 65(17): 7743-50)

Objectives-Fish oil rich in n-3 polyunsaturated fatty acids (PUFAs) or n-3 PUFAs have been shown to reduce the incidence of coronary heart disease. Here we investigated the effect of highly purified eicosapentaenoic acid (EPA) on production of adiponectin, the only established antiatherogenic and antiinflammatory adipocytokine, in rodent models of obesity and human obese subjects. Methods and Results-We demonstrated that EPA increases adiponectin secretion in genetically obese ob/ob mice and high-fat diet-induced obese mice. In the in vitro coculture of adipocytes and macrophages, EPA reversed the coculture-induced decrease in adiponectin secretion at least in part through downregulation of tumor necrosis factor-␣ in macrophages. We also showed significant increase in plasma adiponectin concentrations in human obese subjects after a 3-month treatment with EPA (1.8 g daily). Multivariate regression analysis revealed that EPA treatment is the only independent determinant of plasma adiponectin concentrations. Conclusion-This study demonstrates that EPA increases adiponectin secretion in rodent models of obesity and human obese subjects, possibly through the improvement of the inflammatory changes in obese adipose tissue. Because EPA has reduced the risk of major coronary events in a large-scale, prospective, randomized clinical trial, this study provides important insight into its therapeutic implication in obesity-related metabolic sequelae. (Arterioscler Thromb Vasc Biol. 2007;27:1918-1925.)Key Words: adipocytes Ⅲ adiponectin Ⅲ EPA Ⅲ macrophages Ⅲ obesity T he adipose tissue has a high capacity to secrete many biologically active substances (or adipocytokines) such as leptin and tumor necrosis factor-␣ (TNF␣). 1 Dysregulation of pro-and antiinflammatory adipocytokine production is associated with the metabolic syndrome, suggesting that inflammatory changes within obese adipose tissue may critically contribute to the development of many aspects of the metabolic syndrome and results in diabetes and atherosclerosis. Among numerous adipocytokines, adiponectin is unique in that it is the only established adipocytokine with antiatherogenic and antiinflammatory properties. 2,3 It also increases tissue fat oxidation, leading to reduced levels of fatty acids (FAs) and tissue triglyceride content, thus enhancing insulin sensitivity in the liver and skeletal muscle. 2,4,5 Because plasma adiponectin concentrations are decreased in obese subjects, 1,2 extensive researches have been aimed at the upregulation of adiponectin and its cognate receptors (AdipoR1 and AdipoR2) for the treatment of obesityrelated metabolic sequelae. 2 Previous studies showed that the adipose tissue is markedly infiltrated by macrophages in several models of rodent obesities and human obese subjects, 6,7 suggesting that macrophages participate in the inflammatory pathways that are activated in obese adipose tissue. Using an in vitro coculture system composed of adipocytes and macrophages, we have demonstrated that a paracrine loop involving saturate...

Blood vessels change their caliber to adapt to the demands of tissues or organs for oxygen and nutrients. This event is mainly organized at the capillary level and requires a sizesensing mechanism. However, the molecular regulatory mechanism involved in caliber size modification in blood vessels is not clear. Here we show that apelin, a protein secreted from endothelial cells under the activation of Tie2 receptor tyrosine kinase on endothelial cells, plays a role in the regulation of caliber size of blood vessel through its cognate receptor APJ, which is expressed on endothelial cells. During early embryogenesis, APJ is expressed on endothelial cells of the new blood vessels sprouted from the dorsal aorta, but not on pre-existing endothelial cells of the dorsal aorta. Apelin-deficient mice showed narrow blood vessels in intersomitic vessels during embryogenesis. Apelin enhanced endothelial cell proliferation in the presence of vascular endothelial growth factor and promoted cell-to-cell aggregation. These results indicated that the apelin/APJ system is involved in the regulation of blood vessel diameter during angiogenesis.

Genes involved in the transforming growth factor ␤ (TGF-␤) signaling pathway are frequently altered in several types of cancers, and a gastric tumor suppressor RUNX3 appears to be an integral component of this pathway. We reported previously that apoptosis is notably reduced in Runx3 ؊/؊ gastric epithelial cells. In the present study, we show that a proapoptotic gene Bim was transcriptionally activated by RUNX3 in the gastric cancer cell lines SNU16 and SNU719 treated with TGF-␤. The human Bim promoter contains RUNX sites, which are required for its activation. Furthermore, a dominant negative form of RUNX3 comprised of amino acids 1 to 187 increased tumorigenicity of SNU16 by inhibiting Bim expression. In Runx3 ؊/؊ mouse gastric epithelium, Bim was down-regulated, and apoptosis was reduced to the same extent as that in Bim ؊/؊ gastric epithelium. We confirmed comparable expression of TGF-␤1 and TGF-␤ receptors between wild-type and Runx3 ؊/؊ gastric epithelia and reduction of Bim in TGF-␤1 ؊/؊ stomach. These results demonstrate that RUNX3 is responsible for transcriptional up-regulation of Bim in TGF-␤-induced apoptosis.

OBJECTIVE-GPR40 is a G protein-coupled receptor regulating free fatty acid-induced insulin secretion. We generated transgenic mice overexpressing the hGPR40 gene under control of the mouse insulin II promoter and used them to examine the role of GPR40 in the regulation of insulin secretion and glucose homeostasis.RESEARCH DESIGN AND METHODS-Normal (C57BL/6J) and diabetic (KK) mice overexpressing the hGPR40 gene under control of the insulin II promoter were generated, and their glucose metabolism and islet function were analyzed.RESULTS-In comparison with nontransgenic littermates, hGPR40 transgenic mice exhibited improved oral glucose tolerance with an increase in insulin secretion. Although islet morphologic analysis showed no obvious differences between hGPR40 transgenic and nontransgenic mice, isolated islets from hGPR40 transgenic mice had enhanced insulin secretion in response to high glucose (16 mmol/l) compared with those from nontransgenic mice, and they both had similar low glucose (3 mmol/l)-stimulated insulin secretion. In addition, hGPR40 transgenic islets significantly increased insulin secretion against a naturally occurring agonist palmitate in the presence of 11 mmol/l glucose. hGPR40 transgenic mice were also found to be resistant to high-fat diet-induced glucose intolerance, and hGPR40 transgenic mice harboring KK background showed augmented insulin secretion and improved oral glucose tolerance compared with nontransgenic littermates. CONCLUSIONS-Our results suggest that GPR40 may have a role in regulating glucose-stimulated insulin secretion and plasma glucose levels in vivo and that pharmacological activation of GPR40 may provide a novel insulin secretagogue beneficial for the treatment of type 2 diabetes.

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