Hirohito Yoneyama

pp60c-src activation in lung adenocarcinoma

Nine src family members are known including c-Src, c-Yes, c-Lck, c-Fyn, c-Hck, c-Lyn, c-Blk, c-Fgr and c-Yrk. They encode proteins with molecular weights of 55-62 kilodaltons (kDa), which are either cytoplasmic or membrane-associated protein tyrosine kinases. A close correlation exists between an elevated pp60c-src tyrosine kinase activity and cell transformation. However, the level of activation of pp60c-src in non-small cell lung cancers (NSCLC) remains obscure. The aim of this study was to examine the level of activity of pp60c-src in NSCLC. pp60c-src expression and in vitro protein tyrosine kinase activity in lung cancer tissue samples were measured by western blotting and in vitro kinase assays and compared with those in the surrounding non-tumour lung tissue from the same patient. pp60c-src phosphorylation was assessed by two-dimensional tryptic phosphopeptide mapping. The kinase activity of pp60c-src was significantly activated in NSCLC, especially in adenocarcinomas. In addition, the pp60c-src kinase activity increased with the size of the adenocarcinoma. Two-dimensional tryptic phosphopeptide mapping showed dephosphorylation of pp60c-src at Tyr 530 in adenocarcinomas. The proto-oncogene product, pp60c-src, was activated in NSCLC, especially in adenocarcinomas, in part through the dephosphorylation of Tyr 530. Our results suggest that activation of pp60c-src might play an important role in the progression of lung adenocarcinomas.

L-Arginine improves endothelial function in renal artery of hypertensive Dahl rats.

Objectives To clarify whether endothelium-derived contracting factor (EDCF) is developed in renal artery of hypertensive Dahl rats and whether prolonged oral l-arginine treatments prevent development of EDCF and hypertension. Design The effect of prolonged salt treatment with or without l-arginine on the renal artery was examined. Methods and Results Dahl salt-sensitive and -resistant rats were fed a 0.4 or an 8% NaCl diet for 4 weeks. High sodium intake increased arterial pressure in Dahl salt-sensitive rats. The rings of renal arteries were suspended for isometric tension recording. Only in the hypertensive rats, more than 1 μmol/l acetylcholine induced an endothelium-dependent contraction response. The contraction was completely inhibited by indomethacin or ONO-3708 [prostaglandin H2 (PGH2)/thromboxane A2 (TXA2) receptor antagonist], and partially inhibited by OKY-046 (TXA2 synthetase inhibitor). Acetylcholine-induced relaxation was significantly depressed in hypertensive rats, which was partially improved by SQ29548 (PGH2/TXA2 receptor antagonist). Oral l-arginine, but not ONO-8809 (orally active PGH2/TXA2 receptor antagonist) treatment, inhibited the contraction and amended the relaxation. The endothelium-independent contraction to TXA2 receptor agonist U46619 and relaxation to nitroprusside were not altered by l-arginine treatment. The l-Arginine treatment reduced blood pressure and sodium retention with increases in urinary NO−−2/NO−−3 and cGMP excretion. Hydralazine treatment also inhibited development of EDCF. Conclusions The present results suggest that impaired endothelium-dependent relaxation to acetylcholine is caused in part by induction of EDCF synthesis/release in renal arteries of hypertensive Dahl rats. l-arginine can attenuate sodium retention and development of hypertension, which lead to a decrease in EDCF synthesis in renal arteries.

Induction of LOX-1 and iNOS expressions by ischemia-reperfusion of rat kidney and the opposing effect of l-arginine

Lectin‐like oxidized low‐density lipoprotein receptor (LOX‐1) is a newly identified endothelial cell surface major receptor for oxidatively modified low‐density lipoprotein. Progression of arthrosclerosis in the donor organ after organ transplantation is a major problem. We hypothesized that ischemia‐reper‐fusion induces LOX‐1. After 1 h ischemia of bilateral kidneys plus 3, 6, or 12 h reperfusion, we first revealed that LOX‐1 mRNA expression was increased in renal cortex and medulla at 6 h after reperfusion, which was decreased by l‐arginine supplement. Plasma nitric oxide (NO) end‐product nitrite plus nitrate and inducible nitric oxide synthase (NOS) expression were increased after reperfusion of 6 h. However, NOS substrate l‐arginine did not augment but markedly decreased plasma NO end product, because l‐arginine supplement suppressed inducible NOS expression in kidney. We hypothesized that available l‐arginine is depleted by ischemia‐reperfusion, leading to inducible NOS induction. Ischemia decreased l‐arginine levels in kidney and l‐arginine supplement increased NO end products in renal cortex in the earliest phase of reperfusion. These results disclosed for the first time that a deficiency in l‐arginine by ischemia reperfusion causes uncoupling of constitutive NOS, which induces inducible NOS and LOX‐1, implying why l‐arginine is effective for stroke or transplantation in preventing atherosclerotic progress.—Kosaka, H., Yoneyama, H., Zhang, L., Fujii, S., Yamamoto, A., Igarashi, J. Induction of LOX‐1 and iNOS expressions by ischemia‐reperfusion of rat kidney and the opposing effect of L‐arginine. FASEB J. 17, 636–643 (2003)

Effect of the anti-diabetic drug metformin in hepatocellular carcinoma in vitro and in vivo.

Metformin is a commonly used oral anti-hyperglycemic agent of the biguanide family. Recent studies suggest that metformin may reduce cancer risk and improve prognosis. However, the antitumor mechanism of metformin in several types of cancers, including hepatocellular carcinoma (HCC), has not been elucidated. The goal of the present study was to evaluate the effects of metformin on HCC cell proliferation in vitro and in vivo, and to study microRNAs (miRNAs) associated with the antitumor effect of metformin in vitro. We used the cell lines Alex, HLE and Huh7, and normal hepatocytes to study the effects of metformin on human HCC cells. In an in vivo study, athymic nude mice bearing xenograft tumors were treated with metformin or left untreated. Tumor growth was recorded after 4 weeks, and the expression of cell cycle-related proteins was determined. Metformin inhibited the proliferation of Alex, HLE and Huh7 cells in vitro and in vivo. Metformin blocked the cell cycle in G0/G1 in vitro and in vivo. This blockade was accompanied by a strong decrease of G1 cyclins, especially cyclin D1, cyclin E and cyclin-dependent kinase 4 (Cdk4). In addition, microRNA (miRNA) expression was markedly altered by the treatment with metformin in vitro and in vivo. In addition, various miRNAs induced by metformin also may contribute to the suppression of tumor growth. Our results demonstrate that metformin inhibits the growth of HCC, possibly by inducing G1 cell cycle arrest through the alteration of microRNAs.

Acute production of vascular superoxide by angiotensin II but not by catecholamines.

Objective To determine whether vascular superoxide is rapidly released by angiotensin II and is involved in vascular contraction. Design The effect of superoxide dismutase (SOD) on angiotensin II induced elevation of mean arterial blood pressure was measured. Subsequently, acute production of vascular superoxide by angiotensin II and its effect on isometric tension were measured in rat aortic rings. The effects of catecholamines were concomitantly measured. Methods and results The acute pressor effects of angiotensin II were significantly reduced when rats were pretreated intravenously with SOD. When angiotensin II was added on aortic segments in the presence of Cypridina luciferin analog, immediate elevations of chemiluminescence were observed which were inhibited by SOD. Furthermore, angiotensin II-induced elevations of isometric tension in aortic rings were significantly reduced by SOD. The effects of epinephrine and norepinephrine were concomitantly measured and were not significant. Conclusions The acute superoxide producing effect is likely to be specific to angiotensin II, because such a significant modification of the effects was not observed for catecholamines. Our results suggest that angiotensin II causes acute vascular superoxide production, which may be involved in the acute pressor effects.

Blockade of neuronal nitric oxide synthase alters the baroreflex control of heart rate in the rabbit

In previous studies we used N G-nitro-l-arginine (l-NNA) to investigate the role of nitric oxide (NO) in baroreflex control of heart rate (HR) and renal sympathetic nerve activity (RSNA).l-NNA increased resting mean arterial pressure (MAP), decreased HR, and did not change or slightly decreased RSNA. These changes complicated the assessment of the central effects of NO on the baroreflex control of HR and RSNA. Therefore, in the present study the effects of the relatively selective neuronal NO synthase inhibitor 7-nitroindazole (7-NI) on the baroreflex control of HR and RSNA were investigated in rabbits. Intraperitoneal injection of 7-NI (50 mg/kg) had no effect on resting HR, MAP, or RSNA. 7-NI significantly reduced the lower plateau of the HR-MAP baroreflex curve from 140 ± 4 to 125 ± 4 and from 177 ± 10 to 120 ± 9 beats/min in conscious and anesthetized preparations, respectively ( P < 0.05). In contrast, there was no significant difference in the RSNA-MAP curves before and after 7-NI administration in conscious or anesthetized preparations. These data suggest that blockade of neuronal NO synthase influences baroreflex control of HR but not of RSNA in rabbits.In previous studies we used NG-nitro-L-arginine (L-NNA) to investigate the role of nitric oxide (NO) in baroreflex control of heart rate (HR) and renal sympathetic nerve activity (RSNA). L-NNA increased resting mean arterial pressure (MAP), decreased HR, and did not change or slightly decreased RSNA. These changes complicated the assessment of the central effects of NO on the baroreflex control of HR and RSNA. Therefore, in the present study the effects of the relatively selective neuronal NO synthase inhibitor 7-nitroindazole (7-NI) on the baroreflex control of HR and RSNA were investigated in rabbits. Intraperitoneal injection of 7-NI (50 mg/kg) had no effect on resting HR, MAP, or RSNA. 7-NI significantly reduced the lower plateau of the HR-MAP baroreflex curve from 140 +/- 4 to 125 +/- 4 and from 177 +/- 10 to 120 +/- 9 beats/min in conscious and anesthetized preparations, respectively (P < 0.05). In contrast, there was no significant difference in the RSNA-MAP curves before and after 7-NI administration in conscious or anesthetized preparations. These data suggest that blockade of neuronal NO synthase influences baroreflex control of HR but not of RSNA in rabbits.

Potassium supplementation increases sodium excretion and nitric oxide production in hypertensive dahl rats

The present study was designed to investigate whether antihypertensive and natriuretic effects of K were achieved by elevation of nitric oxide (NO) production in Dahl salt-sensitive (DS) rats. The rats were placed in individual metabolic cage and fed a high sodium diet with or without K supplementation for 4 weeks. K supplementation counteracted the blood-pressure raising effect of NaCl. K supplementation significantly enhanced sodium excretion and reduced sodium retention, increased the urinary nitrite plus nitrate excretion and kidney constitutive NO synthase activity in salt-loaded DS rats. These effect did not occur in the rats fed a low sodium diet with K supplementation. These results suggest that K supplementation attenuates development of hypertension with reduction of sodium retention in salt-loaded DS rats, which is mediated by the recovery of salt-induced NO production mechanism.

Selenium deficiency is associated with insulin resistance in patients with hepatitis C virus–related chronic liver disease

The relationship between selenium (Se) deficiency and insulin resistance has not much been established in persistent hepatitis C virus (HCV) infection, although Se deficiency is often observed in patients with liver cirrhosis. We hypothesized that the decreased serum Se levels were associated with the severity of hepatic fibrosis or insulin resistance in patients with HCV-related chronic liver disease (CLD). To test the hypothesis, 52 patients with HCV-related CLD including chronic hepatitis and liver cirrhosis were enrolled in this study. The severity of hepatic fibrosis was divided into 4 categories (F(1) through F(4)) according to the new Inuyama classification. Insulin resistance was defined by the homeostasis model for assessment of insulin resistance value. Serum Se levels significantly declined in proportion to the severity of hepatic fibrosis and were positively correlated with serum albumin (r = 0.372, P = .0065) and zinc (r = 0.403, P = .0081) concentrations. Serum Se levels were also linked to glutathione peroxidase activities in the sera of the enrolled patients (r = 0.374, P = .0148). By contrast, serum Se levels were inversely correlated with the homeostasis model for assessment of insulin resistance values (r = -0.304, P = .0338). However, serum Se levels were independent of HCV genotype and loads of HCV-RNA. These findings suggest that Se deficiency was associated with the severity of hepatic fibrosis in patients with HCV-related CLD and that Se deficiency was likely to be one of the factors contributing to insulin resistance in those patients.

Galectin-9 suppresses the growth of hepatocellular carcinoma via apoptosis in vitro and in vivo

Galectin-9, a soluble β-galactoside-binding animal lectin, evokes apoptosis in various human cancer cell lines. The galectin-9 antitumor effect against hepatocellular carcinoma (HCC) is, however, unknown. We investigated whether galectin-9 suppresses HCC growth in vitro and in vivo. We assessed the antitumor effect of galectin-9 on HCC cells by conducting WST-8 assay in vitro and xenograft model analysis in vivo. Galectin-9-induced apoptosis was evaluated by FACS and ELISA in vitro and by TUNEL stain in vivo. Cell cycle alteration was profiled by FACS. Caspases were profiled by colorimetry. MicroRNAs related to the galectin-9 antitumor effects were determined using microarrays, and their antitumor effect was confirmed in a transfection study in vitro. The expression levels of the target proteins of the miRNAs extracted above were analyzed by western blot analysis. To summarize the results, galectin-9 inhibited the growth of the HCC cell lines HLE and Li-7 in vitro and Li-7 in vivo inducing apoptosis. Cell cycle turnover was not arrested in HLE and Li-7 cells in vitro. miR-1246 was similarly extracted both in vitro and in vivo, which sensitized Li-7 cells to apoptosis when transfected into the cells. DYRK1A, a target protein of miR-1246 was downregulated in Li-7 cells. Caspase-9 was upregulated in Li-7 cells in vitro and in vivo. In conclusion, galectin-9 inhibited the growth of HCC cells by apoptosis, but not cell cycle arrest, in vitro and in vivo. miR-1246 mediated signals of galectin-9, possibly through miR-1246-DYRK1A-caspase-9 axis. Galectin-9 might be a candidate agent for HCC chemotherapy.

Exacerbation of Insulin Resistance and Hepatic Steatosis Deriving from Zinc Deficiency in Patients with HCV-Related Chronic Liver Disease

The role of zinc (Zn) in hepatic steatosis of patients with HCV-related chronic liver disease (CLD-C) remains uncertain, although persistent HCV infection often evokes hepatic steatosis. The primary purpose of this study was to elucidate the contribution of Zn deficiency to hepatic steatosis in patients with CLD-C. Fifty nondiabetic patients with CLD-C were enrolled. Hepatic 4-hydroxy-2-nonenal (4-HNE) expression was examined using an immunohistochemical procedure as a marker for lipid peroxidation. Serum ferritin levels were assessed for iron overload. Insulin resistance was evaluated using the values of the homeostasis model for assessment of insulin resistance (HOMA-IR). The severity of hepatic steatosis was graded on the classification system proposed by Brunt and colleagues. Serum Zn levels were inversely correlated with serum ferritin levels in the patients with CLD-C (r = −0.382, p = 0.0062). Serum ferritin levels were strongly associated with the HOMA-IR values (r = 0.476, p = 0.0005). Therefore, Zn deficiency resulted in insulin resistance through iron overload. Moreover, serum Zn levels were significantly decreased in proportion to the level of hepatic 4-HNE expression, which was enhanced as hepatic steatosis developed. Then, Zn deficiency eventually seemed to exacerbate hepatic steatosis by way of an increase in lipid peroxidation. However, the serum Zn levels were not associated with either loads of HCV-RNA or HCV genotypes. These data suggest that, in patients with CLD-C, Zn deficiency promotes insulin resistance by exacerbating iron overload in the liver and induces hepatic steatosis by facilitating lipid peroxidation.