Is lung resection appropriate for late octogenarians? Surgical outcomes of patients aged ≥ 80 years with lung cancer.

PURPOSE: This study aimed to determine the outcomes and prognostic factors associated with octogenarians who underwent pulmonary resection for lung cancer. METHODS/PATIENTS: From 2009 to 2018, 76 octogenarians underwent pulmonary surgery for lung cancer at the Kanazawa Medical University, Japan. They were divided into two groups (early and late octogenarians), and their clinicopathological characteristics and outcomes were investigated. Overall survival rates and recurrence-free survival rates were determined using Kaplan-Meier curves. Univariate and multivariate analyses were performed to identify prognostic factors. RESULTS: Limited surgery was performed more often in the late octogenarian group; however, most perioperative factors were not significantly different between the two groups. The 3-year overall survival and recurrence-free survival rates were 61.2% and 52.8%, respectively. The median observation period was 37.5 (8.9-112.3) months postoperatively. Kaplan-Meier curves showed that age ≥ 85 years (late octogenarian), smoking history, and squamous cell carcinoma on histology were associated with worse survival rates. Multivariate analysis identified age ≥ 85 years (late octogenarian) (p = 0.011) and cigarette smoking (p = 0.025) as unfavorable prognostic factors for overall survival and recurrence-free survival, respectively. CONCLUSIONS: Most octogenarians with an indication for surgery can tolerate pulmonary surgery. However, owing to the limitations of this retrospective, single-center study, future studies involving multiple-institutions are required to confirm our findings.

Sulforaphane reduces advanced glycation end products (AGEs)-induced inflammation in endothelial cells and rat aorta.

BACKGROUND AND AIMS: Advanced glycation end products (AGEs)-receptor RAGE interaction evokes oxidative stress and inflammatory reactions, thereby being involved in endothelial cell (EC) damage in diabetes. Sulforaphane is generated from glucoraphanin, a naturally occurring isothiocyanate found in widely consumed cruciferous vegetables, by myrosinase. Sulforaphane has been reported to protect against oxidative stress-mediated cell and tissue injury. However, effects of sulforaphane on AGEs-induced vascular damage remain unclear. METHODS AND RESULTS: In this study, we investigated whether and how sulforaphane could inhibit inflammation in AGEs-exposed human umbilical vein ECs (HUVECs) and AGEs-injected rat aorta. Sulforaphane treatment for 4 or 24 h dose-dependently inhibited the AGEs-induced increase in RAGE, monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecular-1 (VCAM-1) gene expression in HUVECs. AGEs significantly stimulated MCP-1 production by, and THP-1 cell adhesion to, HUVECs, both of which were prevented by 1.6 µM sulforaphane. Sulforaphane significantly suppressed oxidative stress generation and NADPH oxidase activation evoked by AGEs in HUVECs. Furthermore, aortic RAGE, ICAM-1 and VCAM-1 expression in AGEs-injected rats were increased, which were suppressed by simultaneous infusion of sulforaphane. CONCLUSION: The present study demonstrated for the first time that sulforaphane could inhibit inflammation in AGEs-exposed HUVECs and AGEs-infused rat aorta partly by suppressing RAGE expression through its anti-oxidative properties. Inhibition of the AGEs-RAGE axis by sulforaphane might be a novel therapeutic target for vascular injury in diabetes.

Nutritional management of anastomotic leakage after colorectal cancer surgery using elemental diet jelly.

BACKGROUND/AIMS: Anastomotic leakage is major complication of colorectal surgery. Total parenteral nutrition (TPN) and fasting are conservative treatments for leakage in the absence of peritonitis in Japan. Elemental diet (ED) jelly is a completely digested formula and is easily absorbed without secretion of digestive juices. The purpose of this study was to assess the safety of ED jelly in management of anastomotic leakage. METHODOLOGY: Six hundred and two patients who underwent elective surgery for left side colorectal cancer from January 2008 to December 2011 were included in the study. Pelvic drainage was performed for all patients. Sixty-three (10.5%) patients were diagnosed with an anastomotic leakage, and of these, 31 (5.2%) without diverting stoma were enrolled in this study. RESULTS: Sixteen patients received TPN (TPN group) and 15 patients received ED jelly (ED group). The duration of intravenous infusion was significantly shorter in the ED group than in the TPN group (15 days versus 25 days, P= 0.008). In the TPN group, catheter infection was occurred in 2 patients who required re-insertion of the catheter. CONCLUSION: Conservative management of anastomotic leakage after colorectal surgery with ED jelly appears to be a safe and useful approach.

Serum levels of toxic AGEs (TAGE) may be a promising novel biomarker in development and progression of NASH.

Nonalcoholic fatty liver disease (NAFLD) ranges from simple steatosis to nonalcoholic steatohepatitis (NASH), leads to fibrosis and potentially cirrhosis, liver failure, and hepatocellular carcinoma, and is one of the most common causes of liver disease worldwide. NAFLD has also been implicated in other medical conditions such as insulin resistance, obesity, metabolic syndrome, hyperlipemia, hypertension, cardiovascular disease, and diabetes. Continuous hyperglycemia has been implicated in the pathogenesis of diabetic micro- and macro-vascular complications via various metabolic pathways, and numerous hyperglycemia-induced metabolic and hemodynamic conditions exist, including the increased generation of various types of advanced glycation end-products (AGEs). We recently demonstrated that glyceraldehyde-derived AGEs (Glycer-AGEs), the predominant components of toxic AGEs (TAGE), played an important role in the pathogenesis of angiopathy in diabetic patients. Moreover, a growing body of evidence suggests that the interaction between TAGE and the receptor for AGEs may alter intracellular signaling, gene expression, and the release of pro-inflammatory molecules and also elicits the generation of oxidative stress in numerous types of cells including hepatocytes and hepatic stellate cells. Serum levels of TAGE were significantly higher in NASH patients than in those with simple steatosis and healthy controls. Moreover, serum levels of TAGE inversely correlated with adiponectin (adiponectin is produced by adipose tissue and is an anti-inflammatory adipokine that can increase insulin sensitivity). Furthermore, immunohistochemical staining of TAGE showed intense staining in the livers of patients with NASH. Serum levels of TAGE may be a useful biomarker for discriminating NASH from simple steatosis. The administration of atorvastatin (10 mg daily) for 12 months significantly improved NASH-related metabolic parameters and significantly decreased serum levels of TAGE. The steatosis grade and NAFLD activity score were also significantly improved. These results demonstrated that atorvastatin decreased the serum levels of TAGE in NASH patients with dyslipidemia and suggest the usefulness of TAGE as a biomarker for the attenuation of NASH. Serum levels of TAGE were significantly higher in non-B or non-C hepatocellular carcinoma (NBNC-HCC) patients than in NASH subjects without HCC or control subjects. TAGE may be involved in the pathogenesis of NBNC-HCC, and could, therefore, be a biomarker that could discriminate NBNC-HCC from NASH. We propose that serum levels of TAGE are promising novel targets for the diagnosis of and therapeutic interventions against NASH.

Empagliflozin, an Inhibitor of Sodium-Glucose Cotransporter 2 Exerts Anti-Inflammatory and Antifibrotic Effects on Experimental Diabetic Nephropathy Partly by Suppressing AGEs-Receptor Axis.

Advanced glycation end products (AGEs) and receptor RAGE play a role in diabetic nephropathy. We have previously shown that increased glucose uptake into proximal tubular cells via sodium-glucose cotransporter 2 (SGLT2) stimulates oxidative stress generation and RAGE expression, thereby exacerbating the AGE-induced apoptosis in this cell type. However, the protective role of SGLT2 inhibition against the AGE-RAGE-induced renal damage in diabetic animals remains unclear. In this study, we investigated the effects of empagliflozin, SGLT2 inhibitor on AGE-RAGE axis, inflammatory and fibrotic reactions, and tubular injury in the kidney of streptozotocin-induced diabetic rats.Administration of empagliflozin for 4 weeks significantly improved hyperglycemia and HbA1c, and decreased expression levels of AGEs, RAGE, 8-hydroxydeoxyguanosine (8-OHdG), and F4/80, markers of oxidative stress and macrophages, respectively, in the diabetic kidney. Although empagliflozin did not reduce albuminuria, it significantly decreased urinary excretion levels of 8-OHdG and L-fatty acid binding protein, a marker of tubular injury. Moreover, inflammatory and fibrotic gene expression such as monocyte chemoattractant protein-1, intercellular adhesion molecule-1, plasminogen activator inhibitor-1, transforming growth factor-ß, and connective tissue growth factor was enhanced in the diabetic kidney, all of which were prevented by empagliflozin. The present study suggests that empagliflozin could inhibit oxidative, inflammatory and fibrotic reactions in the kidney of diabetic rats partly via suppression of the AGE-RAGE axis. Blockade of the increased glucose uptake into renal proximal tubular cells by empagliflozin might be a novel therapeutic target for tubulointerstitial damage in diabetic nephropathy.

Bazedoxifene blocks AGEs-RAGE-induced superoxide generation and MCP-1 level in endothelial cells.

Advanced glycation endproducts (AGEs) and their receptor (RAGE) play a role in vascular complications in diabetes. We have previously shown that 17ß-estradiol at 10 nmol/l, a nearly identical plasma concentration to that during mid-pregnancy, up-regulates RAGE expression in endothelial cells. The finding might suggest the involvement of 17ß-estradiol in the deterioration of vascular complications in diabetes during pregnancy. However, the effects of the selective estrogen receptor modulator, bazedoxifene, on oxidative and inflammatory reactions in AGEs-exposed endothelial cells remain unknown. In this study, we addressed the issue. Ten nmol/l 17ß-estradiol increased RAGE and monocyte chemoattractant protein-1 (MCP-1) gene and protein expression in human umbilical vein endothelial cells (HUVECs), both of which were blocked by 10 nmol/l bazedoxifene. Bazedoxifene at 10 nmol/l also significantly inhibited the AGEs-induced superoxide generation, RAGE and MCP-1 gene and protein expression in HUVECs. The present study suggests that blockade of the AGEs-RAGE axis by bazedoxifene might be a novel therapeutic target for preventing vascular damage in diabetes, especially in postmenopausal women.

Linagliptin blocks renal damage in type 1 diabetic rats by suppressing advanced glycation end products-receptor axis.

Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in diabetic nephropathy. We have recently found that linagliptin, an inhibitor of dipeptidyl peptidase-4 (DPP-4) suppresses the AGE-induced oxidative stress generation and intercellular adhesion molecule-1 (ICAM-1) gene expression in endothelial cells. However, whether linagliptin could have beneficial effects on experimental diabetic nephropathy in a glucose-lowering independent manner remains unknown. To address the issue, this study examined the effects of linagliptin on renal damage in streptozotocin-induced diabetic rats. Serum levels of DPP-4 were significantly elevated in diabetic rats compared with control rats. Although linagliptin treatment for 2 weeks did not improve hyperglycemia in diabetic rats, linagliptin significantly reduced AGEs levels, RAGE gene expression, and 8-hydroxy-2'-deoxyguanosine, a marker of oxidative stress in the kidney of diabetic rats. Furthermore, linagliptin significantly reduced albuminuria, renal ICAM-1 mRNA levels, and lymphocyte infiltration into the glomeruli of diabetic rats. Our present study suggests that linagliptin could exert beneficial effects on diabetic nephropathy partly by blocking the AGE-RAGE-evoked oxidative stress generation in the kidney of streptozotocin-induced diabetic rats. Inhibition of DPP-4 by linagliptin might be a promising strategy for the treatment of diabetic nephropathy.

Metformin inhibits advanced glycation end products (AGEs)-induced growth and VEGF expression in MCF-7 breast cancer cells by suppressing AGEs receptor expression via AMP-activated protein kinase.

Metformin use has been reported to decrease breast cancer incidence and mortality in diabetic patients. We have previously shown that advanced glycation end products (AGEs) and their receptor (RAGE) interaction stimulate growth and/or migration of pancreatic cancer and melanoma cells. However, effects of metformin on AGEs-RAGE axis in breast cancers remain unknown. We examined here whether and how metformin could block the AGEs-induced growth and vascular endothelial growth factor (VEGF) expression in MCF-7 breast cancer cells. Cell proliferation was measured with an electron coupling reagent WST-1 based colorimetric assay. Gene expression level was evaluated by real-time reverse-transcription polymerase chain reactions. AGEs significantly increased cell proliferation of MCF-7 cells, which was completely prevented by the treatment with 0.01 or 0.1 mM metformin or anti-RAGE antibodies. Furthermore, metformin at 0.01 mM completely suppressed the AGEs-induced upregulation of RAGE and VEGF mRNA levels in MCF-7 cells. An inhibitor of AMP-activated protein kinase, compound C significantly blocked the growth-inhibitory and RAGE and VEGF suppressing effects of metformin in AGEs-exposed MCF-7 cells. Our present study suggests that metformin could inhibit the AGEs-induced growth and VEGF expression in MCF-7 breast cancer cells by suppressing RAGE gene expression via AMP-activated protein kinase pathway. Metformin may protect against breast cancer expansion in diabetic patients by blocking the AGEs-RAGE axis.

Glucose-dependent insulinotropic polypeptide (GIP) inhibits signaling pathways of advanced glycation end products (AGEs) in endothelial cells via its antioxidative properties.

Glucose-dependent insulinotropic polypeptide (GIP) is one of the incretins, a gut hormone secreted from K cells in the intestine in response to food intake. It could be a potential therapeutic target for the treatment of patients with type 2 diabetes. However, effects of GIP on vascular injury remain unknown. Since interaction of advanced glycation end products (AGEs) with their receptor RAGE has been shown to play a crucial role in vascular damage in diabetes, this study investigated whether and how GIP blocked the deleterious effects of AGEs on human umbilical vein endothelial cells (HUVECs). GIP receptor was expressed in HUVECs. GIP, an analogue of cyclic AMP or inhibitors of NADPH oxidase inhibited the AGE-induced reactive oxygen species (ROS) generation in HUVECs. Furthermore, GIP reduced both RAGE mRNA and protein levels in HUVECs. GLP-1 also blocked the AGE-induced increase in mRNA levels of vascular cell adhesion molecule-1 (VCAM-1) and plasminogen activator inhibitor-1 in HUVECs. In addition, an antioxidant N-acetylcysteine mimicked the effects of GIP on RAGE and VCAM-1 gene expression in HUVECs. Our present study suggests that GIP could block the signal pathways of AGEs in HUVECs by reducing ROS generation and subsequent RAGE expression probably via GIP receptor-cyclic AMP axis.

Rosuvastatin blocks advanced glycation end products-elicited reduction of macrophage cholesterol efflux by suppressing NADPH oxidase activity via inhibition of geranylgeranylation of Rac-1.

Adenosine triphosphate-binding membrane cassette transporter A1 (ABCA1) and ABCG1 play a crucial role in macrophage cholesterol efflux, which is a novel therapeutic target for atherosclerosis. Advanced glycation end products (AGE) and their receptor RAGE axis is involved in accelerated atherosclerosis in diabetes as well. However, the role of AGE-RAGE axis in macrophage cholesterol efflux is not fully understood. We examined here whether AGE-RAGE axis could impair cholesterol efflux from human macrophage cells, THP-1 cells by suppressing ABCA1 and ABCG1 expression. We further investigated the effects of rosuvastatin on cholesterol efflux from AGE-exposed THP-1 cells. AGE increased reactive oxygen species generation in THP-1 cells, which was completely inhibited by rosuvastatin, anti-RAGE-antibody or diphenylene iodonium chloride (DPI), an inhibitor of NADPH oxidase. The antioxidative effect of rosuvastatin on AGE-exposed THP-1 cells was significantly prevented by geranylgeranyl pyrophosphate (GGPP). AGE decreased ABCA1 and ABCG1 mRNA levels, and subsequently reduced cholesterol efflux from THP-1 cells, which was prevented by GGPP. DPI mimicked the effects of rosuvastain. The results demonstrated that rosuvastatin could inhibit the AGE-induced reduction of THP-1 macrophage cholesterol efflux by suppressing NADPH oxidase activity via inhibition of geranylgeranylation of Rac-1. Our present study provides a novel beneficial aspect of rosuvastatin in diabetes; rosuvastain may prevent the development and progression of atherosclerosis in diabetes by not only reducing serum cholesterol level, but also by improving cholesterol efflux from foam cells of the arterial wall via blocking the harmful effects of AGE on macrophages.

Pathophysiological role of pigment epithelium-derived factor (PEDF) in hepatic disorders.

Pigment epithelium-derived factor (PEDF) is a glycoprotein that belongs to the superfamily of serine protease inhibitors with a potent neuronal differentiating activity. Recently, PEDF is found to be a highly effective inhibitor of pathological angiogenesis in both cell culture and animal models. Further, it has also been shown to have neuroprotective, anti-oxidative and anti-inflammatory properties, any of which could potentially be exploited as a therapeutic option for the treatment of cardiometabolic disorders, neurodegenerative disease and cancers. However, as far as we know, there are few comprehensive reviews to deal with the involvement of PEDF in hepatic disease. This article summarizes the pathophysiological role of PEDF for various liver diseases such as hepatic insulin resistance, alcoholic and nonalcoholic liver disease, and hepatocellular carcinoma, and its potential therapeutic implication in these devastating disorders.

The role of PEDF in tumor growth and metastasis.

Pigment epithelium-derived factor (PEDF), one of the non-inhibitory serpines, is widely expressed throughout the body. Although PEDF was initially identified as a neuronal differentiation factor, more attention has been paid to its anti-angiogenic activity. Additionally, recent researches have demonstrated that PEDF has an anti-tumor effect against several human neoplasms. This review focuses on the pathological role of PEDF in tumors, especially tumor growth and metastasis. PEDF is an endogenous anti-tumor factor and its clinical application seems quite promising, although there is much to be further investigated.

Structure-function relationships of PEDF.

Pigment epithelial-derived factor (PEDF) is a 50-kDa secreted glycoprotein that belongs to the noninhibitory serpin. It has an alpha/beta core serine-protease inhibitor domain, 3 major beta-sheets, and 10 alpha-helices. Although PEDF does not inhibit either serine or cysteine proteinases, PEDF exerts diverse physiological activities including anti-angiogenesis, anti-vasopermeability, anti-tumor, and neurotrophic activities. Recent studies have shown that a variety of peptides derived from PEDF possess activities similar to those of the parent molecule through interactions with the extracellular matrix, binding to PEDF receptors, nuclear localization and phosphorylation. Thus, peptides derived from PEDF have therapeutic potential for various diseases and therefore, it is important to clarify the structure-function relationship of PEDF. In this review, we summarize structural features of PEDF that could affect various target organs such as blood vessels, tumors, and the central nervous system. In addition, since PEDF is recently identified as a regulator for glucose and lipid metabolism, we also discuss PEDF structures specially related to insulin-sensitizing and triglyceridereducing properties.

Anti-vasopermeability effects of PEDF in retinal-renal disorders.

The vascular system has an important function of supplying tissues with oxygen and nutrients and clearing waste products. Therefore, the microvasculature must be sufficiently permeable to allow the free, bidirectional passage of small molecules and gases and, to a lesser extent, of plasma proteins. It is well recognized that vascular endothelial growth factor (VEGF) can increase vascular permeability, thus playing important roles in variety of disorders, including diabetic retinopathy, nephrotic syndrome, brain edema, acute respiratory distress syndrome, and sepsis-associated hypotension. However, how vascular permeability is controlled by anti-permeable factors is not fully understood. We have recently found that pigment epithelium derived factor (PEDF), a 50 kD glycoprotein, inhibits retinal, renal and brain hyperpermeability by counteracting the biological actions of VEGF. In this review, we discuss about the pathophysiological role of PEDF in vascular permeability, especially focusing on retinal-renal disorders.

Branched-chain amino acids and pigment epithelium-derived factor: novel therapeutic agents for hepatitis c virus-associated insulin resistance.

Recent clinical studies have shown that patients with chronic liver disease are insulin resistant. Of all etiologies of chronic liver disease including non-alcoholic fatty liver disease, the one that causes the most sever insulin resistance is hepatitis C virus (HCV) infection. Since insulin resistance promotes inflammatory and fibrogenic reactions in the liver, thus leading to the development of liver cirrhosis and hepatocellular carcinoma (HCC) in patients with HCV infection, amelioration of insulin sensitivity may inhibit the progression of HCV-associated liver disease, and could improve the survival of these patients. HCV directly causes insulin resistance through HCV core protein-elicited proteasomal degradation of insulin receptor substrates and subsequent inactivation of intracellular insulin signaling molecules such as Akt. Furthermore, tumor necrosis factor-alpha (TNF-alpha) and/or triglyceride accumulation-induced nuclear factor-kappaB (NF-kappaB) activation in the liver is shown to play a role in insulin resistance in patients with HCV-related chronic liver disease as well. We, along with others, have recently found that branched-chain amino acids (BCAAs) and pigment epithelium-derived factor (PEDF) could improve the HCV-associated insulin resistance via suppression of NF-kappaB and preservation of insulin signaling pathway. In this review, we discuss the mechanisms for the actions of BCAAs and PEDF, and their clinical implications in insulin resistance of chronic liver disease in patients with HCV infection. We also discuss here which chemical structures could contribute to insulin-sensitization in patients with HCV infection.

Pigment epithelium-derived factor (PEDF) ameliorates advanced glycation end product (AGE)-induced hepatic insulin resistance in vitro by suppressing Rac-1 activation.

Advanced glycation end products (AGEs) could be implicated in insulin resistance. However, the molecular mechanisms underlying this are not fully understood. Since pigment epithelium-derived factor (PEDF) blocks the AGE-signaling pathways, we examined here whether and how PEDF improves insulin resistance in AGE-exposed hepatoma cells, Hep3B cells. Proteins were extracted from Hep3B cells, immunoprecipitated with or without insulin receptor substrate-1 (IRS-1) antibodies, and subjected to Western blot analysis. Glycogen synthesis was measured using [ (14)C]-d-glucose. AGE induced Rac-1 activation and increased phosphorylation of IRS-1 at serine-307 residues, JNK, c-JUN, and IkappaB kinase in association with decreased IkappaB levels in Hep3B cells. PEDF or overexpression of dominant negative Rac-1 blocked these effects of AGE on Hep3B cells. Further, AGEs decreased tyrosine phosphorylation of IRS-1, and subsequently reduced the association of p85 subunit of phosphatidylinositol 3-kinase with IRS-1 and glycogen synthesis in insulin-exposed Hep3B cells, all of which were inhibited by PEDF. Our present study suggests that PEDF could improve the AGE-elicited insulin resistance in Hep3B cells by inhibiting JNK- and IkappaB kinase-dependent serine phosphorylation of IRS-1 via suppression of Rac-1 activation. PEDF may play a protective role against hepatic insulin resistance in diabetes.

Possible involvement of tobacco-derived advanced glycation end products (AGEs) in an increased risk for developing cancers and cardiovascular disease in former smokers.

Tobacco smoking is one of the strongest risk factors for various disorders such as lung cancers and cardiovascular disease (CVD). Further, former smokers remain at an increased risk for developing lung cancers and CVD even years after they stop smoking. These observation suggest that expression levels of some of the genes related to tobacco smoking may not return to levels similar to never smokers and could be permanently altered despite prolonged smoking cessation, thereby being involved in the development of lung cancers and CVD. The modification, aggregation, and deposition of proteins are a prominent part of many pathological processes and can play a direct role in tissue damage. Advanced glycation end products (AGEs) have been shown to play a role in the development of many of the pathological sequelae of aging and diabetes such as CVD and cancer growth and metastasis. Moreover, there are several papers to show that tobacco smoke is a source of toxic reactive glycation products. Further, recent epidemiological and prospective data have supported the concept of 'metabolic memory', a long-term influence of previous hyperglycemia on the development of CVD in diabetes. Potential mechanism for propagating this 'memory' is considered to be the non-enzymatic glycation of proteins because the process of formation and accumulation of AGEs are most compatible with the theory. Therefore, it is conceivable that tobacco-derived AGEs are also involved in the increased risk for developing cancers and CVD in former smokers. In this paper, we would like to propose the possible ways of testing our hypotheses. Are tissue levels of AGEs still higher in former smokers, compared with age-, sex- and other confounders-matched non-smokers? If the answer is yes, are the tissue levels of AGEs following smoking cessation decreased? If we examine the effects of smoking cessation as a function of years since quitting, is the extent of decrease in tissue AGEs levels parallel to that of risk reduction for developing cancers and CVD? Further, are genes that are permanently altered despite prolonged smoking cessation identical to those that regulated by AGEs? These investigations could clarify whether tobacco-derived AGEs are involved in sustained tissue injury in former smokers.

Telmisartan, an angiotensin II type 1 receptor blocker, inhibits advanced glycation end-product (AGE)-elicited hepatic insulin resistance via peroxisome proliferator-activated receptor-gamma activation.

This study examined whether telmisartan, a unique angiotensin II type 1 receptor blocker (ARB) with peroxisome proliferator-activated receptor-gamma (PPAR-gamma)-modulating activity, improved insulin resistance in advanced glycation end-product (AGE)-exposed human hepatoma (Hep3B) cells. AGE increased phosphorylation of insulin receptor substrate-1 (IRS-1) at serine-307 residues in Hep3B cells. It also decreased tyrosine phosphorylation of IRS-1 and, subsequently, reduced the association of the p85 subunit of phosphatidylinositol 3-kinase with IRS-1 and glycogen synthesis in insulin-exposed Hep3B cells, all of which were inhibited by telmisartan. The insulin-sensitizing properties of telmisartan in AGE-exposed Hep3B cells were significantly blocked by GW9662, an inhibitor of PPAR-gamma. Candesartan, another ARB, did not affect AGEs-induced serine phosphorylation of IRS-1 at serine-307 residues in Hep3B cells. Our study suggests that telmisartan could improve AGE-elicited insulin resistance in Hep3B cells by inhibiting serine phosphorylation of IRS-1, at least in part, via activation of PPAR-gamma. Telmisartan may play a protective role against hepatic insulin resistance in diabetes.

Bay w 9798, a dihydropyridine structurally related to nifedipine with no calcium channel-blocking properties, inhibits tumour necrosis factor-alpha-induced vascular cell adhesion molecule-1 expression in endothelial cells by suppressing reactive oxygen species generation.

Dihydropyridine-based calcium antagonists (DHPs) are widely used to treat hypertension. We have previously shown that nifedipine, one of the most popular DHPs, blocks tumour necrosis factor-alpha (TNF-alpha)-induced monocyte chemoattractant protein-1 as well as vascular cell adhesion molecule-1 (VCAM-1) expression in endothelial cells by suppressing reactive oxygen species generation (ROS). The molecular mechanism is still to be elucidated, however, because endothelial cells do not possess voltage-operated L-type calcium channels. The aim of this study was to determine in TNF-alpha-exposed human umbilical vein endothelial cells (HUVECs) whether and how Bay w 9798, a dihydropyridine structurally related to nifedipine with no calcium antagonistic properties, may suppress VCAM-1 expression, a key molecule which mediates the adhesion of monocytes to vasculature in the early stages of atherosclerosis. In HUVECs, 10 ng/ml TNF-alpha for 4 h stimulated ROS generation and subsequently upregulated VCAM-1 mRNA levels, both of which were dose-dependently blocked by Bay w 9798. The results demonstrated that Bay w 9798 inhibited VCAM-1 expression in TNF-alpha-exposed cells by suppressing ROS generation. They suggest that the anti-inflammatory and anti-oxidative properties of nifedipine and Bay w 9798 may be ascribed to the dihydropyridine structure, which is common to both molecules and has no calcium antagonistic ability.