Far-Infrared Irradiation Decreases Proliferation in Basal and PDGF-Stimulated VSMCs Through AMPK-Mediated Inhibition of mTOR/p70S6K Signaling Axis

BACKGROUND

Far-infrared (FIR) irradiation has been reported to improve diverse cardiovascular diseases, including heart failure, hypertension, and atherosclerosis. The dysregulated proliferation of vascular smooth muscle cells (VSMCs) is well established to contribute to developing occlusive vascular diseases such as atherosclerosis and in-stent restenosis. However, the effects of FIR irradiation on VSMC proliferation and the underlying mechanism are unclear. This study investigated the molecular mechanism through which FIR irradiation inhibited VSMC proliferation.

METHODS

We performed cell proliferation and cell death assay, adenosine 5'-triphosphate (ATP) assay, inhibitor studies, transfection of dominant negative (dn)-AMP-activated protein kinase (AMPK) α1 gene, and western blot analyses. We also conducted confocal microscopic image analyses and ex vivo studies using isolated rat aortas.

RESULTS

FIR irradiation for 30 minutes decreased VSMC proliferation without altering the cell death. Furthermore, FIR irradiation accompanied decreases in phosphorylation of the mammalian target of rapamycin (mTOR) at Ser2448 (p-mTOR-Ser2448) and p70 S6 kinase (p70S6K) at Thr389 (p-p70S6K-Thr389). The phosphorylation of AMPK at Thr172 (p-AMPK-Thr172) was increased in FIR-irradiated VSMCs, which was accompanied by a decreased cellular ATP level. Similar to in vitro results, FIR irradiation increased p-AMPK-Thr172 and decreased p-mTOR-Ser2448 and p-p70S6K-Thr389 in isolated rat aortas. Pre-treatment with compound C, a specific AMPK inhibitor, or ectopic expression of dn-AMPKα1 gene, significantly reversed FIR irradiation-decreased VSMC proliferation, p-mTOR-Ser2448, and p-p70S6K-Thr389. On the other hand, hyperthermal stimulus (39°C) did not alter VSMC proliferation, cellular ATP level, and AMPK/mTOR/p70S6K phosphorylation. Finally, FIR irradiation attenuated platelet-derived growth factor (PDGF)-stimulated VSMC proliferation by increasing p-AMPK-Thr172, and decreasing p-mTOR-Ser2448 and p-p70S6K-Thr389 in PDGF-induced in vitro atherosclerosis model.

CONCLUSION

These results show that FIR irradiation decreases the basal and PDGF-stimulated VSMC proliferation, at least in part, by the AMPK-mediated inhibition of mTOR/p70S6K signaling axis irrespective of its hyperthermal effect. These observations suggest that FIR therapy can be used to treat arterial narrowing diseases, including atherosclerosis and in-stent restenosis.

Nucleus-targeted delivery of nitric oxide in human mesenchymal stem cells enhances osteogenic differentiation

Nitric oxide (NO) is an important gaseous signaling molecule in various physiological processes, which functions through interactions with its acceptor molecules located in organelles. NO has an extremely short half-life, making it challenging to experimentally achieve effective NO levels in organelles to study these interactions. Here we developed an organelle-specific, peptide-based NO delivery material that targets the nucleus. NO was attached to the SH group of a cysteine residue inserted into the N-terminus of a cell-penetrating peptide (CPP) conjugated to varying repeats of the nuclear localization signal (NLS), which we denoted NO-CysCPP-NLS, through S-nitrosylation. NO-CysCPP-NLS strongly induced osteogenic differentiation of mesenchymal stem cells. This delivery concept can be extended to cells other than stem cells to elucidate the effects of NO release in the nucleus. Furthermore, conjugation of NO to CysCPP fused to mitochondria- or lysosome-targeting signals can be used to deliver NO to other organelles such as mitochondria and lysosomes, respectively.

Global longitudinal strain to predict myocardial fibrosis in patients in carbon monoxide poisoning

Background

Carbon monoxide (CO) inhibits oxygen delivery and subsequently causes ischemic changes that can lead to myocardial damage. Late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) reflects myocardial fibrosis and detects subclinical myocardial damage in patients with acute CO poisoning. However, CMR is expensive and hard to perform in patients with neurologic deficit. Therefore, this study aims to investigate which echocardiographic parameters could predict the presence of myocardial fibrosis represented by LGE in CO intoxication patients.

Methods

This prospective observational study included 128 consecutive patients (Mean age: 52.2±16.2) with acute CO poisoning and elevated troponin I (defined as >0.045 ng/mL) at the emergency department of a tertiary university hospital. All participants underwent hyperbaric oxygen therapy (HBOT). CMR and conventional echocardiography with 2D speckle-tracking were performed within 7 days. Subjects were categorized into late gadolinium enhancement (LGE) and no LGE group according to the CMR findings.

Results

Mean left ventricular (LV) ejection fraction (EF) and global longitudinal strain (GLS) were 57.0±10.0% and −16.3±3.7% respectively. LGE was observed in 89 (69.5%) patients and the most common pattern was mid-wall involvement. Clinical characteristics such as age, sex, shock, time elapsed from rescue to HBOT, and the level of troponin I were not different between groups with LGE and without LGE. Among echocardiographic parameters, LV EF was not significantly different between groups (LGE: 56.0±10.5% vs 59.3±8.1%, p=0.089). LV GLS was more impaired in patients with LGE compared to those without LGE (−15.7±3.8% vs −17.9±3.0%, p=0.003). In multivariate logistic analysis, LV GLS was independently associated with the presence of LGE [Odds ratio (OR) 1.279, 95% confidence interval (CI) (1.047–1.563), p=0.016], but not LV EF.

Conclusion

In patients with acute CO poisoning and elevated troponin I, LV GLS predicted the presence of LGE in CMR. These finding suggest that subclinical myocardial dysfunction represented by LV GLS may reflect the burden of CO induced myocardial fibrosis.

Funding Acknowledgement

Type of funding sources: None.

Valproic acid decreases vascular smooth muscle cell proliferation via protein phosphatase 2A-mediated p70 S6 kinase inhibition

Valproic acid (VPA) has been used to treat epilepsy and bipolar disorder. Although the abnormal proliferation of vascular smooth muscle cells (VSMCs) is a well-established contributor to the development of various vascular diseases including atherosclerosis, the effect of VPA on VSMC proliferation and its mechanism of action have not been fully revealed. Herein, we investigated the molecular mechanism by which VPA inhibits rat VSMC proliferation. VPA dose-dependently decreased VSMC proliferation, which was accompanied by the dose-dependent decrease in phosphorylation of p70 S6 kinase (p70S6K) at Thr389 (p-p70S6K-Thr³⁸⁹), and overexpression of the p70S6K-T389E mutant gene significantly reversed VPA-inhibited VSMC proliferation. Co-treatment with okadaic acid, a specific protein phosphatase 2A (PP2A) inhibitor, significantly restored p-p70S6K-Thr³⁸⁹. Furthermore, knockdown of PP2Ac gene expression by siRNA significantly reversed VPA-inhibited p-p70S6K-Thr³⁸⁹ and VSMC proliferation. Confocal microscopic analyses and co-immunoprecipitation results clearly showed that the physical binding of p70S6K and PP2Ac was promoted by VPA. Valpromide, a VPA's structural derivative with no histone deacetylase (HDAC) inhibition activity, as well as VPA and sodium butyrate, an HDAC inhibitor similar to VPA, decreased VSMC proliferation and p-p70S6K-Thr³⁸⁹, indicating that HDAC is not involved in VPA-inhibited VSMC proliferation. Finally, the inhibitory effects of VPA on p-p70S6K-Thr³⁸⁹ and VSMC proliferation were reiterated in a platelet-derived growth factor (PDGF)-induced in vitro atherosclerosis model. In conclusion, our results demonstrate that VPA decreased cell proliferation via PP2A-mediated inhibition of p-p70S6K-Thr³⁸⁹ in basal and PDGF-stimulated VSMCs. The results suggest that VPA could be used in the treatment and prevention of atherosclerosis and in-stent restenosis.

Immune response to hepatitis B vaccination and factors associated with poor immune response among healthcare workers

Background

Hepatitis B virus (HBV) infection is a major global health problem, and healthcare workers (HCWs) are at high risk for HBV infection. Current guidelines strongly recommend immunization and screening for high-risk groups.

Aims

We evaluated immunization and screening for HBV vaccination, assessed post-vaccination immune status of HCW's and characterized potential risk factors associated with poor immune response.

Materials and Methods

From January 2010 to December 2018, we retrospectively analyzed comprehensive health checkup data for a total of 303 HCWs who received an HBV vaccination. After vaccination, HBV surface antibody (anti-HBs) titers were collected and the distribution of immune response types was determined. Risk factors for poor immune responses were identified using logistic regression.

Results

A total of 213 HCWs were analyzed after exclusion based on the exclusion criteria. In total, 28 (13.2%) HCWs had anti-HBs titers <100 mIU/mL (hyporesponsive/nonresponsive groups), and 185 (86.8%) had anti-HBs titers ≥100 mIU/mL (hyperresponsive group). Follow-up observations found that 75% (21/28) of the hyporesponsive/nonresponsive groups did not have increased anti-HBs titers or did not maintain an increased response. A multivariate analysis showed that HBV antibody titers at the time of employment were a significant risk factor (OR, 6.12; CI, 1.34-27.93; P = 0.019).

Conclusions

More attention should be paid to groups that are hyporesponsive/nonresponsive after vaccination and to those with low anti-HBs titers at the beginning of employment. HCWs can be further protected from HBV if their results are discussed at postvaccination follow-ups.

Far-infrared irradiation inhibits breast cancer cell proliferation independently of DNA damage through increased nuclear Ca2+/calmodulin binding modulated-activation of checkpoint kinase 2

Far-infrared (FIR) irradiation is reported to inhibit cell proliferation in various types of cancer cells; the underlying mechanism, however, remains unclear. We explored the molecular mechanisms using MDA-MB-231 human breast cancer cells. FIR irradiation significantly inhibited cell proliferation and colony formation compared to hyperthermal stimulus, with no alteration in cell viability. No increase in DNA fragmentation or phosphorylation of DNA damage kinases including ataxia-telangiectasia mutated kinase, ataxia telangiectasia and Rad3-related kinase, and DNA-dependent protein kinase indicated no DNA damage. FIR irradiation increased the phosphorylation of checkpoint kinase 2 (Chk2) at Thr68 (p-Chk2-Thr⁶⁸) but not that of checkpoint kinase 1 at Ser345. Increased nuclear p-Chk2-Thr⁶⁸ and Ca²⁺/CaM accumulations were found in FIR-irradiated cells, as observed in confocal microscopic analyses and cell fractionation assays. In silico analysis predicted that Chk2 possesses a Ca²⁺/calmodulin (CaM) binding motif ahead of its kinase domain. Indeed, Chk2 physically interacted with CaM in the presence of Ca²⁺, with their binding markedly pronounced in FIR-irradiated cells. Pre-treatment with a Ca²⁺ chelator significantly reversed FIR irradiation-increased p-Chk2-Thr⁶⁸ expression. In addition, a CaM antagonist or small interfering RNA-mediated knockdown of the CaM gene expression significantly attenuated FIR irradiation-increased p-Chk2-Thr⁶⁸ expression. Finally, pre-treatment with a potent Chk2 inhibitor significantly reversed both FIR irradiation-stimulated p-Chk2-Thr⁶⁸ expression and irradiation-repressed cell proliferation. In conclusion, our results demonstrate that FIR irradiation inhibited breast cancer cell proliferation, independently of DNA damage, by activating the Ca²⁺/CaM/Chk2 signaling pathway in the nucleus. These results demonstrate a novel Chk2 activation mechanism that functions irrespective of DNA damage.

Activation of ATM/Akt/CREB/eNOS Signaling Axis by Aphidicolin Increases NO Production and Vessel Relaxation in Endothelial Cells and Rat Aortas

Although DNA damage responses (DDRs) are reported to be involved in nitric oxide (NO) production in response to genotoxic stresses, the precise mechanism of DDR-mediated NO production has not been fully understood. Using a genotoxic agent aphidicolin, we investigated how DDRs regulate NO production in bovine aortic endothelial cells. Prolonged (over 24 h) treatment with aphidicolin increased NO production and endothelial NO synthase (eNOS) protein expression, which was accompanied by increased eNOS dimer/monomer ratio, tetrahydrobiopterin levels, and eNOS mRNA expression. A promoter assay using 5'-serially deleted eNOS promoters revealed that Tax-responsive element site, located at -962 to -873 of the eNOS promoter, was responsible for aphidicolin-stimulated eNOS gene expression. Aphidicolin increased CREB activity and ectopic expression of dominantnegative inhibitor of CREB, A-CREB, repressed the stimulatory effects of aphidicolin on eNOS gene expression and its promoter activity. Co-treatment with LY294002 decreased the aphidicolin-stimulated increase in p-CREB-Ser133 level, eNOS expression, and NO production. Furthermore, ectopic expression of dominant-negative Akt construct attenuated aphidicolin-stimulated NO production. Aphidicolin increased p-ATM-Ser1981 and the knockdown of ATM using siRNA attenuated all stimulatory effects of aphidicolin on p-Akt-Ser473, p-CREB-Ser133, eNOS expression, and NO production. Additionally, these stimulatory effects of aphidicolin were similarly observed in human umbilical vein endothelial cells. Lastly, aphidicolin increased acetylcholine-induced vessel relaxation in rat aortas, which was accompanied by increased p-ATM-Ser1981, p-Akt-Ser473, p-CREB-Ser133, and eNOS expression. In conclusion, our results demonstrate that in response to aphidicolin, activation of ATM/Akt/CREB/eNOS signaling cascade mediates increase of NO production and vessel relaxation in endothelial cells and rat aortas.

Anti-malarial Drugs Reduce Vascular Smooth Muscle Cell Proliferation via Activation of AMPK and Inhibition of Smad3 Signaling

Objective

The aim of this study was to investigate the effects of 2 anti-malarial drugs, chloroquine (CQ) and hydroxychloroquine (HCQ), on inhibition of vascular smooth muscle cell (VSMC) proliferation both in vivo and in vitro via Adenosine monophosphate-activated protein kinase (AMPK) activation.

Methods

Protein and mRNA levels were determined by western blot analysis and real-time reverse transcription-polymerase chain reaction in primary rat VSMCs treated with CQ and HCQ, respectively. Cell proliferation was measured by flow cytometry and cell counting. Mice carotid arteries were ligated and treated with CQ or HCQ every other day for 3 weeks. Pathological changes of carotid arteries were visualized by both microscopy and fluorescence microscopy.

Results

CQ and HCQ increase AMPK phosphorylation in VSMCs. Both CQ and HCQ decrease platelet-derived growth factor-induced VSMC proliferation and cell cycle progression in an AMPK-dependent manner. In addition, CQ and HCQ inhibit Smad3 phosphorylation and VSMC proliferation induced by transforming growth factor-β1. Moreover, CQ and HCQ diminished neointimal proliferation in a mouse model of carotid artery ligation-induced neointima formation.

Conclusion

The results demonstrated that CQ and HCQ inhibit cell proliferation and cell cycle progression in VSMCs via the AMPK-dependent signaling pathway. Carotid artery ligation-induced intima thickness was reduced in mouse arteries treated with CQ or HCQ, suggesting a role for antimalarial drugs in treating atherosclerosis and restenosis.

Metformin ameliorates bile duct ligation-induced acute hepatic injury via regulation of ER stress

Cholestasis is a condition in which the bile duct becomes narrowed or clogged by a variety of factors and bile acid is not released smoothly. Bile acid-induced liver injury is facilitated by necrotic cell death, neutrophil infiltration, and inflammation. Metformin, the first-line treatment for type 2 diabetes, is known to reduce not only blood glucose but also inflammatory responses. In this study, we investigated the effects of metformin on liver injury caused by cholestasis with bile acid-induced hepatocyte injury. Static bile acid-induced liver injury is thought to be related to endoplasmic reticulum (ER) stress, inflammatory response, and chemokine expression. Metformin treatment reduced liver injury caused by bile acid, and it suppressed ER stress, inflammation, chemokine expression, and neutrophil infiltration. Similar results were obtained in mouse primary hepatocytes exposed to bile acid. Hepatocytes treated with tauroursodeoxycholic acid, an ER stress inhibitor, showed inhibition of ER stress, as well as reduced levels of inflammation and cell death. These results suggest that metformin may protect against liver injury by suppressing ER stress and inflammation and reducing chemokine expression.

Zearalenone-Induced Interaction between PXR and Sp1 Increases Binding of Sp1 to a Promoter Site of the eNOS, Decreasing Its Transcription and NO Production in BAECs

Zearalenone (ZEN) is a non-steroidal mycotoxin that has various toxicological impacts on mammalian health. Here, we found that ZEN significantly affected the production of nitric oxide (NO) and the expression of endothelial NO synthase (eNOS) of bovine aortic endothelial cells (BAECs). A promoter analysis using 5′-serially deleted human eNOS promoter revealed that the proximal region (−135 to +22) was responsible for ZEN-mediated reduction of the human eNOS promoter activity. This effect was reversed by mutation of two specificity protein 1 (Sp1) binding elements in the human eNOS promoter. A chromatin immunoprecipitation assay revealed that ZEN increased Sp1 binding to the bovine eNOS promoter region (−113 to −12), which is homologous to −135 to +22 of the human eNOS promoter region. We also found that ZEN promoted the binding of the pregnane X receptor (PXR) to Sp1 of the bovine eNOS, consequently decreasing eNOS expression. This reduction of eNOS could have contributed to the decreased acetylcholine-induced vessel relaxation upon ZEN treatment in our ex vivo study using mouse aortas. In conclusion, our data demonstrate that ZEN decreases eNOS expression by enhancing the binding of PXR-Sp1 to the eNOS promoter, thereby decreasing NO production and potentially causing vessel dysfunction.

Telmisartan increases hepatic glucose production via protein kinase C ζ-dependent insulin receptor substrate-1 phosphorylation in HepG2 cells and mouse liver

Background

Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice.

Methods

Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase α (G6Pase-α), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ζ (PKCζ) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice.

Results

Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a 40 μM concentration without a change in G6Pase-α expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 (p-IRS-1-Ser³⁰²) and decreased p-IRS-1-Tyr⁶³² dose-dependently. Telmisartan dose-dependently increased p-PKCζ-Thr⁴¹⁰ which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative PKCζ significantly attenuated telmisartan-induced HGP and p-IRS-1-Ser³⁰² and -inhibited p-IRS-1-Tyr⁶³². Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased p-IRS-1-Ser³⁰² and decreased p-IRS-1-Tyr⁶³², which was accompanied by an increase in p-PKCζ-Thr⁴¹⁰.

Conclusion

These results suggest that telmisartan increases HGP by inducing p-PKCζ-Thr⁴¹⁰ that increases p-IRS-1-Ser³⁰² and decreases p-IRS-1-Tyr⁶³² in a PPARγ-independent manner.

Telmisartan mitigates hyperglycemia-induced vascular inflammation by increasing GSK3β-Ser9 phosphorylation in endothelial cells and mouse aortas

Telmisartan, an angiotensin II type 1 receptor blocker (ARB), attenuates hyperglycemia-aggravated vascular inflammation by decreasing IκB kinase β (IKKβ) expression in endothelial cells. Because glycogen synthase 3β (GSK3β) is involved in inflammatory process by regulating nuclear factor-κB (NF-κB) activity, we investigated whether GSK3β mediates telmisartan-ameliorated vascular inflammation in hyperglycemia-treated endothelial cells and high-fat diet (HFD)-fed mice. Telmisartan remarkably induced GSK3β-Ser⁹ phosphorylation in hyperglycemia-treated endothelial cells that accompanied a decrease in hyperglycemia-induced NF-κB p65-Ser⁵³⁶ phosphorylation, vascular cell adhesion molecule-1 (VCAM-1) expression, and THP-1 monocyte adhesion. Ectopic expression of GSK3β-S9A, a constitutively active mutant of GSK3β, significantly restored complete telmisartan-inhibited NF-κB p65-Ser⁵³⁶ phosphorylation, VCAM-1 expression, and THP-1 monocyte adhesion. In addition, it reversed telmisartan-repressed IKKβ expression. Among the ARB, including losartan and fimasartan, only telmisartan increased GSK3β-Ser⁹ phosphorylation, and telmisartan-induced GSK3β-Ser⁹ phosphorylation remained unchanged by pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist. Finally, in the aortas of HFD-fed mice, telmisartan treatment significantly attenuated HFD-induced upregulation of NF-κB p65-Ser⁵³⁶ phosphorylation, VCAM-1 expression, and IKKβ expression and downregulation of GSK3β-Ser⁹ phosphorylation. Taken together, our findings demonstrated that telmisartan ameliorates hyperglycemia-exacerbated vascular inflammation, at least in part, by inducing GSK3β-Ser⁹ phosphorylation, which consequently inhibits IKKβ expression, NF-κB p65-Ser⁵³⁶ phosphorylation, and VCAM-1 expression in a PPARγ-independent manner.

Plasma neutrophil gelatinase-associated lipocalin levels are positively associated with diabetic retinopathy in patients with Type 2 diabetes

AIM

To assess the relationship between plasma neutrophil gelatinase-associated lipocalin (NGAL) levels and diabetic retinopathy in patients with Type 2 diabetes.

METHODS

In total, 204 patients with Type 2 diabetes were investigated in this cross-sectional study. They were classified as having no diabetic retinopathy, non-proliferative diabetic retinopathy (NPDR) or proliferative retinopathy (PDR), according to the degree of diabetic retinopathy. Thus, diabetic retinopathy in the patients in this study was either NPDR or PDR.

RESULTS

Plasma NGAL concentrations were significantly higher in patients with diabetic retinopathy than in those without. The mean plasma NGAL levels differed significantly according to the severity of diabetic retinopathy (no diabetic retinopathy, 120.8 ng/ml; NPDR, 217.8 ng/ml; PDR, 372.4 ng/ml; P for trend = 0.002) after adjustment for other covariates. In multivariable analysis, plasma NGAL levels were significantly associated with diabetic retinopathy (odds ratio for each standard deviation increase in the logarithmic value, 7.75; 95% confidence interval, 2.04-29.41, P = 0.003).

CONCLUSION

Plasma NGAL levels were positively associated with diabetic retinopathy in patients with Type 2 diabetes.

Disruption of neuronal nitric oxide synthase dimerization contributes to the development of Alzheimer's disease: Involvement of cyclin-dependent kinase 5-mediated phosphorylation of neuronal nitric oxide synthase at Ser(293)

Although previous studies have suggested that neuronal nitric oxide synthase (nNOS)-derived NO has neuroprotective effects on the development of Alzheimer's disease (AD), the underlying molecular mechanisms are not fully elucidated. Here, we investigated whether and how disruption of nNOS dimerization contributes to the development of AD. No differences in synaptic number or expression of synaptic markers, including synaptophysin and postsynaptic density 95, were found in the cortex of 5 × FAD mice, which possess 5 familial AD mutations, at 6 months of age compared with control littermates. nNOS dimerization was disrupted in the 5 × FAD cortex, accompanied by an increase in reactive oxygen species (ROS) production. The subcellular distribution of cyclin-dependent kinase 5 (CDK5) shifted more diffusely toward a cytosolic compartment, but there was no change in total expression. Furthermore, the levels of p25, a CDK5 activator, increased significantly and it colocalized with nNOS in the 5 × FAD cortex. In silico analysis revealed that a new nNOS-specific GSP (glycine-serine-proline) motif was well-conserved across species at nNOS-Ser(293), which is located ahead of the N-terminal hook. This motif was not present in the closely related isoform, endothelial NOS. Motif scan analysis also predicted that CDK5 can phosphorylate nNOS-Ser(293) with a high likelihood. An in vitro phosphorylation assay clearly showed that CDK5/p25 does indeed phosphorylate nNOS-Ser(293). Finally, nNOS-S293D mutant, a phosphomimetic form of nNOS-Ser(293), and nNOS-S293A mutant, a neutral form of nNOS-Ser(293), significantly decreased nNOS dimerization and NO production. Taken together, our results demonstrate that nNOS dimers are disrupted in the 5 × FAD cortex, and nNOS-Ser(293), a potential site of CDK5 phosphorylation, may be involved in the decrease in nNOS dimerization and NO production, and the development of AD.

Ginkgo biloba extract (Egb761) attenuates zinc-induced tau phosphorylation at Ser262 by regulating GSK3β activity in rat primary cortical neurons

In the brain, an excessive amount of zinc promotes the deposition of β-amyloid proteins and the intraneuronal accumulation of neurofibrillary tangles composed of hyperphosphorylated tau proteins. These consequences are key neuropathological traits that reflect Alzheimer's disease. Egb761, a standardized Ginkgo biloba extract, is a powerful antioxidant known to exhibit neuroprotective actions. In this study, we investigated whether Egb761 can counteract the zinc-induced tau phosphorylation in rat primary cortical neurons. To determine the modification of tau phosphorylation by Egb761 treatment, we conducted Western blot analyses, MTT assay, ROS measurements and immunocytochemistry. We found that zinc-induced tau phosphorylation occurred at Ser262 in a time- and dose-dependent manner while other tau sites were not phosphorylated. Tau phosphorylation at Ser262 was increased 30 min after zinc treatment and peaked 3 h after zinc treatment (control: 100 ± 1.2%, 30 min: 253 ± 2.24%, 3 h: 373 ± 1.3%). Interestingly, Egb761 treatment attenuated the zinc-induced tau hyperphosphorylation at Ser262 in a concentration-dependent manner while the antioxidant N-acetylcysteine showed a similar effect. Furthermore, Egb761 prevented the zinc-induced activation of p38 MAPK and GSK3β, as well as the zinc-induced increase in ROS production and neuronal cell death. Lithium chloride also inhibited the zinc-induced tau phosphorylation but did not affect ROS levels. These results suggest the potential of Egb761 for inhibiting the zinc-induced tau phosphorylation at Ser262 through its anti-oxidative actions involving the regulation of GSK3β. Therefore, Egb761 may be a candidate for the treatment of tauopathy present in neurological disorders such as Alzheimer's disease.

Citron Rho-interacting kinase mediates arsenite-induced decrease in endothelial nitric oxide synthase activity by increasing phosphorylation at threonine 497: Mechanism underlying arsenite-induced vascular dysfunction

We reported that arsenite causes an acute decrease in nitric oxide (NO) production by increasing phosphorylation of endothelial NO synthase at threonine 497 (eNOS-Thr(497)); however, the detailed mechanism has not yet been clarified. Here, we investigated the kinase involving in arsenite-stimulated eNOS-Thr(497) phosphorylation. Although treatment with H-89, a known protein kinase A (PKA) inhibitor, inhibited arsenite-stimulated eNOS-Thr(497) phosphorylation, no inhibition was found in cells treated with other PKA inhibitors, including Rp-8-Br-cAMPS or PKI. Based on previous reports, we also tested whether RhoA mediates arsenite-stimulated eNOS-Thr(497) phosphorylation and found that arsenite causes an acute increase in RhoA activity. Ectopic expression of dominant negative (DN)-RhoA significantly reversed arsenite-stimulated eNOS-Thr(497) phosphorylation. An in vitro phosphorylation assay also revealed that the well-known Rho effectors, Rho-associated protein kinase 1/2 (ROCK1/2), directly phosphorylate eNOS-Thr(497). Y27632, a selective ROCK inhibitor, reversed arsenite-stimulated eNOS-Thr(497) phosphorylation. However, overexpression of a small interfering RNA (siRNA) against ROCK1/2 or DN-ROCK did not reverse arsenite-stimulated eNOS-Thr(497) phosphorylation, thereby providing no conclusive evidence of a role for ROCK1/2. Knockdown of PKC-related protein kinase 1/2, another Rho effector, also did not reverse arsenite-stimulated eNOS-Thr(497) phosphorylation. In contrast, we found that transfection with an siRNA against citron Rho-interacting kinase (CRIK), the other downstream effector of Rho, significantly reversed the arsenite-induced eNOS-Thr(497) phosphorylation that was accompanied by restoration of eNOS enzymatic activity repressed by arsenite. Moreover, CRIK directly phosphorylated eNOS-Thr(497)in vitro. Finally, we also found that arsenite increased eNOS-Thr(497) phosphorylation and decreased acetylcholine-induced vessel relaxation in rat aortas. In conclusion, we demonstrate that arsenite acutely inhibits eNOS enzymatic activity and vessel relaxation in part by increasing the RhoA/CRIK/eNOS-Thr(497) phosphorylation signaling axis, which provides a molecular mechanism underlying arsenite-induced impaired vascular diseases.

Arsenite Acutely Decreases Nitric Oxide Production via the ROS-Protein Phosphatase 1-Endothelial Nitric Oxide Synthase-Thr(497) Signaling Cascade

Chronic (>24 h) exposure of arsenite, an environmental toxicant, has shown the decreased nitric oxide (NO) production in endothelial cells (EC) by decreasing endothelial NO synthase (eNOS) expression and/or its phosphorylation at serine 1179 (eNOS-Ser¹¹⁷⁹ in bovine sequence), which is associated with increased risk of vascular diseases. Here, we investigated the acute (<24 h) effect of arsenite on NO production using bovine aortic EC (BAEC). Arsenite acutely increased the phosphorylation of eNOS-Thr⁴⁹⁷, but not of eNOS-Ser¹¹⁶ or eNOS-Ser¹¹⁷⁹, which was accompanied by decreased NO production. The level of eNOS expression was unaltered under this condition. Treatment with arsenite also induced reactive oxygen species (ROS) production, and pretreatment with a ROS scavenger N-acetyl-L-cysteine (NAC) completely reversed the observed effect of arsenite on eNOS-Thr⁴⁹⁷ phosphorylation. Although protein kinase C (PKC) and protein phosphatase 1 (PP1) were reported to be involved in eNOS-Thr⁴⁹⁷ phosphorylation, treatment with PKC inhibitor, Ro318425, and overexpression of various PKC isoforms did not affect the arsenite-stimulated eNOS-Thr⁴⁹⁷ phosphorylation. In contrast, treatment with PP1 inhibitor, calyculin A, mimicked the observed effect of arsenite on eNOS-Thr⁴⁹⁷ phosphorylation. Lastly, we found decreased cellular PP1 activity in arsenite-treated cells, which was reversed by NAC. Overall, our study demonstrates firstly that arsenite acutely decreases NO production at least in part by increasing eNOS-Thr⁴⁹⁷ phosphorylation via ROS-PP1 signaling pathway, which provide the molecular mechanism underlying arsenite-induced increase in vascular disease.

Valproic acid increases NO production via the SH-PTP1-CDK5-eNOS-Ser(116) signaling cascade in endothelial cells and mice

Valproic acid (VPA) with its inhibitory activity of histone deacetylase has been used in the treatment of epilepsy and bipolar disorder associated with cerebrovascular dysfunction. Because nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays a role in the maintenance of vascular function, NO is likely to mediate VPA׳s drug effect, but its effect on NO production remains controversial. We investigated whether and how VPA regulates NO production in bovine aortic endothelial cells (BAECs) and mice. VPA increased NO production in BAECs, which was accompanied by a decrease in phosphorylation of eNOS at serine 116 (eNOS-Ser(116)) and cyclin-dependent kinase 5 at tyrosine 15 (CDK5-Tyr(15)). Ectopic expression of p25, a CDK5 activator, restored the VPA-inhibited eNOS-Ser(116) phosphorylation. In silico analysis revealed that the CDK5-Tyr(15) residue might be a substrate for SH2 domain-containing protein tyrosine phosphatase 1 (SH-PTP1), and CDK5 actually interacted with SH-PTP1. VPA increased SH-PTP1 expression and its activity. Stibogluconate, a specific SH-PTP1 inhibitor, reversed the VPA-inhibited phosphorylation of CDK5-Tyr(15) and eNOS-Ser(116). Knockdown of SH-PTP1 using small interfering RNA also reversed all the observed effects of VPA. Finally, both serum NO level and acetylcholine-induced aortic relaxation increased in VPA-medicated male mice. These increases were accompanied by increased SH-PTP1 expression and decreased phosphorylation of CDK5-Tyr(15) and eNOS-Ser(116) in mouse aortas. In conclusion, VPA increases NO production by inhibiting the CDK5-Tyr(15)-eNOS-Ser(116) phosphorylation axis; this process is mediated by SH-PTP1. VPA may be useful in the treatment of NO-related cerebrocardiovascular diseases.

Serum bilirubin concentrations are positively associated with serum C-peptide levels in patients with Type 2 diabetes

AIMS

To investigate the relationship between physiological serum total bilirubin concentrations and serum C-peptide levels in Korean patients with Type 2 diabetes.

METHODS

A total of 588 patients with Type 2 diabetes were investigated in this cross-sectional study. Fasting C-peptide level, 2-h postprandial C-peptide level and ΔC-peptide (postprandial C-peptide minus fasting C-peptide) level were measured in all patients.

RESULTS

Fasting C-peptide level, postprandial C-peptide level and ΔC-peptide level tended to be higher in patients with higher bilirubin concentrations. Partial correlation analysis showed that serum bilirubin levels were significantly correlated with fasting C-peptide level (r = 0.159, P < 0.001), postprandial C-peptide level (r = 0.209, P < 0.001) and ΔC-peptide level (r = 0.186, P < 0.001) after adjustment for other covariates. In the multivariate model, the association between serum bilirubin concentrations and serum C-peptide levels remained significant after adjustment for confounding factors including age, gender, familial diabetes, hypertension, hyperlipidaemia, BMI, HbA1c , duration of diabetes and associated liver function tests (fasting C-peptide level: β = 0.083, P = 0.041; postprandial C-peptide level: β = 0.106, P = 0.005; ΔC-peptide level: β = 0.096, P = 0.015, respectively).

CONCLUSIONS

Serum bilirubin concentrations within the physiological range were positively associated with serum C-peptide levels in patients with Type 2 diabetes.

Physiological serum bilirubin concentrations are inversely associated with the prevalence of cardiovascular autonomic neuropathy in patients with Type 2 diabetes

AIMS

Although severe hyperbilirubinaemia causes kernicterus in neonates, normal to modestly elevated bilirubin concentrations have been reported to be neuroprotective. However, the relationship between serum bilirubin concentrations and cardiovascular autonomic neuropathy in patients with Type 2 diabetes is currently unknown. This study assessed the relationships between physiological serum total bilirubin concentrations and cardiovascular autonomic neuropathy in patients with Type 2 diabetes.

METHODS

A total of 2991 patients with Type 2 diabetes were investigated in this cross-sectional study. Cardiovascular autonomic neuropathy was diagnosed by a cardiovascular reflex test. According to the American Diabetes Association criteria, the degree of cardiovascular autonomic dysfunction was graded into normal, early, definite and severe. Cardiovascular autonomic neuropathy was either definite or severe in the present study. An analysis of covariance after adjustment for other covariates was performed. A logistic regression model was used to assess an association of cardiovascular autonomic neuropathy with serum total bilirubin tertiles.

RESULTS

Serum total bilirubin concentrations were significantly lower in subjects with cardiovascular autonomic neuropathy. The mean total bilirubin values differed significantly according to the severity of cardiovascular autonomic dysfunction (normal 13.0 μmol/l; early 12.3 μmol/l; definite 11.8 μmol/l; severe 10.1 μmol/l; P for trend < 0.001) after adjustment for other covariates. In multivariate analysis, serum total bilirubin levels were significantly associated with cardiovascular autonomic neuropathy (odds ratio 0.36; 95% CI 0.21-0.63 for the highest vs. the lowest bilirubin tertile, P < 0.001).

CONCLUSIONS

Serum total bilirubin concentrations within the physiologic range are inversely associated with the prevalence of cardiovascular autonomic neuropathy in patients with Type 2 diabetes.

Far-infrared radiation acutely increases nitric oxide production by increasing Ca(2+) mobilization and Ca(2+)/calmodulin-dependent protein kinase II-mediated phosphorylation of endothelial nitric oxide synthase at serine 1179

Repeated thermal therapy manifested by far-infrared (FIR) radiation improves vascular function in both patients and mouse model with coronary heart disease, but its underlying mechanism is not fully understood. Using FIR as a thermal therapy agent, we investigate the molecular mechanism of its effect on endothelial nitric oxide synthase (eNOS) activity and NO production. FIR increased the phosphorylation of eNOS at serine 1179 (eNOS-Ser(1179)) in a time-dependent manner (up to 40min of FIR radiation) in bovine aortic endothelial cells (BAEC) without alterations in eNOS expression. This increase was accompanied by increases in NO production and intracellular Ca(2+) levels. Treatment with KN-93, a selective inhibitor of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and H-89, a protein kinase A inhibitor, inhibited FIR radiation-stimulated eNOS-Ser(1179) phosphorylation. FIR radiation itself also increased the temperature of culture medium. As transient receptors potential vanilloid (TRPV) ion channels are known to be temperature-sensitive calcium channels, we explore whether TRPV channels mediate these observed effects. Reverse transcription-PCR assay revealed two TRPV isoforms in BAEC, TRPV2 and TRPV4. Although ruthenium red, a pan-TRPV inhibitor, completely reversed the observed effect of FIR radiation, a partial attenuation (∼20%) was found in cells treated with Tranilast, TRPV2 inhibitor. However, ectopic expression of siRNA of TRPV2 showed no significant alteration in FIR radiation-stimulated eNOS-Ser(1179) phosphorylation. This study suggests that FIR radiation increases NO production via increasing CaMKII-mediated eNOS-Ser(1179) phosphorylation but TRPV channels may not be involved in this pathway. Our results may provide the molecular mechanism by which FIR radiation improves endothelial function.

P5-14-02: Clinicopathologic and Prognostic Difference of Screen Detected Breast Cancer Compared with Symptomatic Breast Cancer

Background: Breast cancer screening program makes it possible to detect early cancer, thus to reduce breast cancer mortality. The authors studied clinicopathologic characteristics and prognosis of screen detected invasive breast cancer compared with symptomatic breast cancer. Furthermore, we compared the result according to molecular subtypes (luminal A, luminal B, Her2, triple negative), so intended to identify the role of screening in each subtypes. Material and Methods: From January 2002 to June 2008, 3141 patients who underwent operation for the treatment of invasive ductal carcinoma(NOS) at Samsung medical center were included. Among them, 1025 patient were screen detected, 2116 patient were symptomatic, out of screening over 2 years. We reviewed the medical records retrospectively.

Result: Screen detected breast cancer was associated with older patients, smaller tumor size, more hormone receptor- positive, less lymph node involvement, lower stage and reduced mortality compared with symptomatic breast cancer (P &lt; .001). According to the molecular subtype, in luminal A subtype, the result shows better pathologic feature and also favorable overall and recur-free survial significantly.

P5-14-19: Ipsilateral Breast Tumor Recurrence Prediction with Web-Based Normogram in Korea

Purpose Ipsilateral Breast Tumor Recurrence(IBTR!) 2.0 is web-based tool which predict the ten years risk of local recurrence after breast conserving theraphy. This tool integrates seven prognostic factors (patient age, margin status, lymphovascular invasion, tumor size, tumor grade, use of chemotherapy and hormonal therapy) for local recurrence with or without radiation theraphy. To validate IBTR! 2.0 for Korean breast cancer patients, Samsung Medical Center database was used between 1994 and 2001.

Methods The IBTR! 2.0 nomogram was tested against 358 patients who underwent breast conserving surgery with radiation theraphy from Samsung Medical Center between 1994 and 2001. The individual dadabase which was entered into IBTR! 2.0 computer model generate predictive local recurrence rate. The mean predicted and observed 10-year estimates were compared for the entire cohort and for four groups predefined by nomogram-predicted risks: group 1: less than 3%; group 2: 3% to 5%; group 3: 5% to 10%; and group 4: more than 10%.

Results IBTR! version 2.0 predicted an overall 10-year IBTR estimate of 5.5% (95% CI, 5.2 to 5.9), while the observed estimate was 7.69% (20 IBTR cases in 358 patients, 95% CI, 1.6 to 9.3; P=0.59).

The predicted and observed IBTR estimates were: group 1 ( 2 cases in 67 patients): 2.3% versus 2.9%, P=0.53; group 2 (2 cases in 124 patients)): 3.9% versus 4.1%, P=0.18; group 3 (14 cases in 139 patinets): 7.3% versus 4.8%, P=0.13; and group 4 (2 cases in 28 patients): 12.15% versus 7.1%, P=0.61.

Conclusion IBTR! 2.0 is acceptable nomogram for predicting 10 years local recurrence using Samsung medical Center database. This nomogram showed overestimation in group 3, 4, however did not showed statistical differences. This nomogram may assist patient counseling and medical decision making, but prior to using whole Korean patients, this model requires validation with multiple Korean sources.

References

1. Fisher, B., et al., Twenty-year follow-up of a randomized trial comparing total mastectomy, lumpectomy, and lumpectomy plus irradiation for the treatment of invasive breast cancer. N Engl J Med, 2002. 347 (16): p. 1233–41.

2. Liljegren, G., et al., 10-Year results after sector resection with or without postoperative radiotherapy for stage I breast cancer: a randomized trial. J Clin Oncol, 1999. 17 (8): p. 2326–33.

3. Anderson, S.J., et al., Prognosis after ipsilateral breast tumor recurrence and locoregional recurrences in patients treated by breast-conserving therapy in five National Surgical Adjuvant Breast and Bowel Project protocols of node-negative breast cancer. J Clin Oncol, 2009. 27 (15): p. 2466–73.

4. Sanghani, M., et al., Predicting the Risk of Local Recurrence in Patients With Breast Cancer. American Journal of Clinical Oncology, 2007. 30 (5): p. 473–480.

5. Sanghani, M., et al., Validation of a Web-Based Predictive Nomogram for Ipsilateral Breast Tumor Recurrence After Breast Conserving Therapy. Journal of Clinical Oncology, 2010. 28 (5): p. 718–722.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-14-19.

A case of xanthoma disseminatum with spontaneous resolution over 10 years: review of the literature on long-term follow-up

Xanthoma disseminatum (XD) is a rare and potentially progressive non-Langerhans-cell histiocytosis. To date, a few cases of XD with spontaneous complete resolution have been described. The present report describes a 16-year-old girl who presented with yellow to red-brown papules and nodules on her eyelids, cheeks, axillae, back and buttocks. Indirect laryngoscopy showed multiple xanthomatous plaques on the larynx, posterior pharynx, epiglottis, and vocal cords. Additional findings were polyuria, polydipsia, and amenorrhea. Skin biopsy and electron microscopy results confirmed the diagnosis of XD. The patient was treated with fenofibrate, simvastatin, desmopressin, and sex-hormone replacement therapy. Her skin lesions began to slowly fade 6 years after disease onset, eventually resolving spontaneously and completely, but leaving an atrophic scar, frank anetoderma, and persisting diabetes insipidus. This case report together with a review of the English-language literature on the long-term follow-up of XD patients provides additional information on the natural history of this disease.

Abstract P3-10-25: The Prognosis of Metaplastic Breast Cancer Patients Compare to Triple-Negative Breast Cancer Patients

Background: Metaplastic breeast cancer (MBC) is a rare, heterogenous cancer characterized by admixture of adenocarcinoma with metaplastic elements, low hormone receptor expression and poor outcome. This study was planned to assess the clinicopathological chacteristics and immunohistochemical findings of MBC compared to invasive ductal carcinoma (IDC) including the triple-negative subtype (TN-IDC). Material and Methods: We retrospectively reviewed the medical records of 47 MBC and 1,346 IDC patients. Two hundred eighteen TN-IDC patients were included in the 1,346 IDC patients. Between 2005 and 2009, these patients were undergone surgical treatment at the Samsung Medical Center. Patients were reviewed clinicopathologic factors, immunohistochemistry of biologic factors such as ER, PR, HER-2, p53, Ki67, cytokeratine (CK) 5/6, epidermal growth factor receptor (EGFR), and treatment modalities (type of operation, use of chemotherapy, radiotherapy and hormone therapy). Result: The MBC patients presented with a larger tumor size (&gt;T1, 66.0% vs. 44.3.%, P = 0.008), lower lymph node involvement (N0, 73.3% vs. 55.6%, P = 0.03), higher histologic (HG) and nuclear grade (NG) (HG3, 70.0% vs. 41.5%, P = 0.001; NG3,82.6% vs. 46.9%, P &lt; 0.001), fewer estrogen receptor (ER), progesterone receptor (PR) and HER2 positivity (ER+, 4.3% vs. 69.2%, P &lt; 0.001; PR+, 6.4% vs. 63.5%, P &lt; 0.001; HER2+, 0% vs. 27.6%, P &lt; 0.001), higher p53, CK5/6 and EGFR expression (p53+, 63.8% vs.38.8%, P &lt; 0.001; CK5/6+, 71.9% vs.21.5%, P &lt; 0.001; EGFR+, 93.9% vs.21.6%, P &lt;0.001) and more TN subtypes (93.6% vs. 16.2%, P &lt; 0.001) compared to the IDC group. There was no significant difference in clinicopathological characteristics with MBC and TN-IDC except EGFR over expression (EGFR+, 93.9% vs.69.0%, P = 0.017). In follow-up duration (median 30 months, range 2-56 months), seven (14.9%) MBC patients and 98 (7.2%) IDC patients recurred. The 3-year disease-free survival (DFS) rate was 78.1% in the MBC group and 91.1% in IDC group (P &lt;0.001). The 3-year DFS rate was not significantly difference between MBC group and TN-IDC group (78.1% vs. 84.9%, P = 0.114). However, in patients with lymph node metastasis who underwent adjuvant chemotherapy, the 3-year DFS rate was 44.4% in MBC group and 72.5% in TN-IDC group (P = 0.025).

Discussion: In our result, MBC show poorer clinical outcome than IDC. It is not shown significant difference between MBC and TN-IDC. However, MBC patients with nodal metastasis have poorer prognosis than TN-IDC patients with metastasis despite adjuvant chemotherapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-25.

Cyclin-Dependent Kinase 5 Phosphorylates Endothelial Nitric Oxide Synthase at Serine 116

Nitric oxide (NO) production in endothelial cells (EC) is regulated by multisite phosphorylation of specific serine and threonine residues in endothelial NO synthase (eNOS). Among these, eNOS-Ser116 is phosphorylated in the basal state, and its phosphorylation contributes to basal NO production. Here, we investigated the mechanism by which eNOS-Ser116 is phosphorylated during the basal state using bovine aortic EC. Although a previous study suggested that protein kinase C was involved in eNOS-Ser116 phosphorylation, overexpression of various protein kinase C isoforms did not affect eNOS-Ser116 phosphorylation. An in silico analysis using a motif scan revealed that the eNOS-Ser116 residue might be a substrate for proline-directed protein kinases. Roscovitine, a specific inhibitor of cyclin-dependent kinase (CDK), 1, 2, and 5, but not an inhibitor of mitogen-activated protein kinase kinase or glycogen synthase kinase 3β, inhibited eNOS-Ser116 phosphorylation dose dependently. Furthermore, purified CDK1, 2, or 5 directly phosphorylated eNOS-Ser116 in vitro. Ectopic expression of the dominant-negative CDK5 but not dominant-negative CDK1 or dominant-negative CDK2 repressed eNOS-Ser116 phosphorylation and increased NO production. In addition, CDK5 activity was detected in bovine aortic EC, and coimmunoprecipitation and confocal microscopy studies revealed a colocalization of eNOS and CDK5. Cotransfection of CDK5 and p25, the specific CDK5 activator, increased eNOS-Ser116 phosphorylation and decreased NO production, but its parent molecule, p35, and p39, another activator, were not detected in bovine aortic EC, which suggests the existence of a novel CDK5 activator. Overall, this is the first study to find that CDK5 is a physiological kinase responsible for eNOS-Ser116 phosphorylation and regulation of NO production.

Troglitazone acutely inhibits protein synthesis in endothelial cells via a novel mechanism involving protein phosphatase 2A-dependent p70 S6 kinase inhibition

Thiazolidinediones (TZDs), synthetic peroxisome proliferator-activated receptor gamma (PPARgamma) ligands, have been implicated in the inhibition of protein synthesis in a variety of cells, but the underlying mechanisms remain obscure. We report that troglitazone, the first TZD drug, acutely inhibited protein synthesis by decreasing p70 S6 kinase (p70S6K) activity in bovine aortic endothelial cells (BAEC). This inhibition was not accompanied by decreased phosphorylation status or in vitro kinase activity of mammalian target of rapamycin (mTOR). Furthermore, cotreatment with rapamycin, a specific mTOR inhibitor, and troglitazone additively inhibited both p70S6K activity and protein synthesis, suggesting that the inhibitory effects of troglitazone are not mediated by mTOR. Overexpression of the wild-type p70S6K gene significantly reversed the troglitazone-induced inhibition of protein synthesis, indicating an important role of p70S6K. Okadaic acid, a protein phosphatase 2A (PP2A) inhibitor, partially reversed the troglitazone-induced inhibition of p70S6K activity and protein synthesis. Although troglitazone did not alter total cellular PP2A activity, it increased the physical association between p70S6K and PP2A, suggesting an underlying molecular mechanism. GW9662, a PPARgamma antagonist, did not alter any of the observed inhibitory effects. Finally, we also found that the mTOR-independent inhibitory mechanism of troglitazone holds for the TZDs ciglitazone, pioglitazone, and rosiglitazone, in BAEC and other types of endothelial cells tested. In conclusion, our data demonstrate for the first time that troglitazone (and perhaps other TZDs) acutely decreases p70S6K activity through a PP2A-dependent mechanism that is independent of mTOR and PPARgamma, leading to the inhibition of protein synthesis in endothelial cells.

Retinoic acid decreases nitric oxide production in endothelial cells: a role of phosphorylation of endothelial nitric oxide synthase at Ser(1179)

The effects of retinoic acid (RA) on nitric oxide (NO) production are controversial. Furthermore, it has never been studied whether these effects are mediated by direct modulation of phosphorylation of endothelial nitric oxide synthase (eNOS). Using bovine aortic endothelial cells, we found that all-trans RA (atRA) dose- and time-dependently decreased NO production without alteration in eNOS expression. This decrease was accompanied by reduction in eNOS-Ser(1179) phosphorylation. However, atRA did not alter the phosphorylation of eNOS-Ser(116) or eNOS-Thr(497). Concurrently, atRA also decreased the expressions of vascular endothelial growth factor (VEGF) and its receptor KDR/Flk-1, and Akt phosphorylation. Co-treatment with troglitazone, an activator of VEGF expression, reversed the atRA-induced reductions in eNOS-Ser(1179) phosphorylation and NO production, with concomitant restoration in VEGF expression. Direct treatment with VEGF also reversed these inhibitory effects, suggesting an important role for VEGF. Nonetheless, the RARalpha antagonist Ro 41-5253 did not block all the inhibitory effects of atRA, indicating that these inhibitory effects are not mediated by the RA response element (RARE). Thus, atRA decreases eNOS-Ser(1179) phosphorylation through a mechanism that depends on VEGF-KDR/Flk-1-mediated Akt phosphorylation but is independent of RARE, leading to reduction in NO production.

Coordinate expression of the alpha and beta subunits of heterotrimeric G proteins involves regulation of protein degradation in CHO cells

Individual cell types express a characteristic balance between heterotrimeric G protein alpha and betagamma subunits, but little is known about the regulatory mechanism. We systemically examined the regulatory mechanism in CHO cells. We found that expression of Galphas, Galphai2, and Galphaq proteins increased in direct proportion to the increase of Gbeta1gamma2 overexpressed transiently. Expression of Gbeta protein also increased following overexpression of Galphas, Galphai2, and Galphaq. The Gbetagamma overexpression stimulated degradation of Gbeta in contrast to reduction of Galphas degradation. We conclude that coordinate expression of the G protein subunits involves regulation of protein degradation via proteasome in CHO cells.

Nitric oxide production and regulation of endothelial nitric-oxide synthase phosphorylation by prolonged treatment with troglitazone: evidence for involvement of peroxisome proliferator-activated receptor (PPAR) gamma-dependent and PPARgamma-independent signaling pathways

Recently, peroxisome proliferator-activated receptor gamma (PPARgamma) ligands have been reported to increase endothelial NO, but the signaling mechanisms involved are unknown. Using troglitazone, a PPARgamma ligand known as an antidiabetic compound, we investigated the molecular mechanism of its effect on NO production in bovine aortic endothelial cells. Troglitazone increased endothelial NO production in a dose- and time-dependent manner with no alteration in endothelial nitric-oxide synthase (eNOS) expression. The maximal increase ( approximately 3.1-fold) was achieved with 20 microm troglitazone treatment for 12 h, and this increase was accompanied by increases in the expression of vascular endothelial growth factor (VEGF) and its receptor, KDR/Flk-1, and in Akt phosphorylation. Analysis with antibodies specific for each phosphorylated site demonstrated that troglitazone (20 microm treatment for 12 h) significantly increased both the phosphorylation of Ser(1179) of eNOS (eNOS-Ser(1179)) and the dephosphorylation of eNOS-Ser(116) but did not alter eNOS-Thr(497) phosphorylation. Treatment with anti-VEGF antibody to scavenge the increased VEGF induced by troglitazone partially inhibited troglitazone-stimulated NO production. This was accompanied by the attenuation of troglitazone-stimulated increases in the phosphorylation of Akt and eNOS-Ser(1179) with no alteration in eNOS-Ser(116) dephosphorylation. We also found that bisphenol A diglycidyl ether, a PPARgamma antagonist, partially inhibited troglitazone-stimulated NO production with a concomitant reduction in VEGF-KDR/Flk-1-Akt-mediated eNOS-Ser(1179) phosphorylation but with no alteration in eNOS-Ser(116) dephosphorylation induced by troglitazone. Taken together, our results demonstrate that prolonged treatment with troglitazone increases endothelial NO production by at least two independent signaling pathways: PPARgamma-dependent, VEGF-KDR/Flk-1-Akt-mediated eNOS-Ser(1179) phosphorylation and PPARgamma-independent, eNOS-Ser(116) dephosphorylation.

Effect of glycolic acid on UVB-induced skin damage and inflammation in guinea pigs

OBJECTIVES

Recently the use of glycolic-acid-containing cosmetics has received increased public interest in their supposed ability to reduce wrinkles, roughness, age spots and other skin damage. However, the safety of such products when used excessively or chronically, especially by photosensitive people, is being questioned. The purpose of this study was to examine the effects of glycolic acid alone or in combination with UVB on skin damage and inflammatory response.

METHOD

Guinea pigs were treated with glycolic acid (from 1 to 7 mg/cm(2)) alone or in combination with UVB (0.4 or 3 J/cm(2)) for 14 days. Skin damage was evaluated by scoring the skin irritation value by the method of Draize and by histopathological observations. Cyclooxygenase 2 (COX-2) expression and prostaglandin E(2) (PGE(2)) production were also assessed.

RESULTS

Glycolic acid caused an increase in the level of skin damage in a dose- and time-dependent manner. Lower doses (1 and 3 mg/cm(2)) of glycolic acid mostly caused erythema and eschar, and these consequently formed scales, whereas higher doses (5 and 7 mg/cm(2)) of glycolic acid caused redness, edema and necrotic ulceration. Glycolic acid also increased the thickness of the epidermal layer, reduced the organization of the stratum corneum and eventually destroyed some parts of the epidermal layer at 7 mg/cm(2). UVB (0.4 and 3 J/cm(2)) caused redness and edema as well as reduced the integrity of the stratum corneum. Glycolic acid enhanced the UVB-induced skin damage. The magnitude of the damage caused by combined UVB and glycolic acid treatment was much greater than that caused by glycolic acid or UVB alone. Moreover, partial destruction of the epidermal layer was observed in skin treated with 3 J/cm(2) UVB and 3 mg/cm(2) glycolic acid. However, glycolic acid did not change the basal and UVB-induced PGE(2) production and COX-2 protein expression.

CONCLUSION

These results show that glycolic acid causes skin damage in a dose- and time-dependent manner and that it enhances UVB-induced skin damage without accompanying PGE(2) production or COX-2 protein expression. Therefore, caution should be exercised by those using glycolic acid on a chronic basis or excessively. Moreover, those with photosensitive skins and those more exposed to the sun should be particularly careful.

Enhanced IL-18 expression in common skin tumors

Interleukin-18 (IL-18) has been found to have multiple effects upon various cells involved in inflammatory response. Recently we reported that B16 murine melanoma cells are able to produce IL-18, which is involved in the regulation of intracellular reactive oxygen intermediates (ROI) and Fas-ligand expression, indicating that IL-18 plays key role in the tumor activity of melanoma. In this study, we investigated the pattern of IL-18 expression in the human system. IL-18 production was tested by enzyme linked immunosorbent assay (ELISA) assay in various tumor cell lines, including Raji (Burkitt's lymphoma), IM-9 (B lymphoblast), Jurkat (acute T cell leukemia), SK-MES-1 (squamous cell carcinoma (SCC) cell line), SK-MEL-2, G-361, DM-4, and DX-3 (melanoma cell lines). ELISA tests showed that IL-18 was highly expressed in malignant skin tumors such as SK-MES-1, SK-MEL-2, G-361, DM-4, and DX-3 cell lines, thus suggesting that IL-18 production may be associated with the malignancy of skin tumors. Here, we report that enhanced IL-18 expression is positively correlated with malignant skin tumors such as SCC and melanoma, suggesting the importance role of IL-18 in malignancy of skin tumors. Taken together, expression of IL-18 by tumor cells in human skin tissue may provide an important clue to understand the pathogenesis of malignant skin tumors.

Synthesis and characterization of a novel extracellular polysaccharide by Rhodotorula glutinis

The aim of this work was to characterize an exopolysaccharide by Rhodotorula glutinis KCTC 7989 and to investigate the effect of the culture conditions on the production of this polymer. The extracellular polysaccharide (EPS) produced from this strain was a novel acidic heteropolysaccharide composed of neutral sugars (85%) and uronic acid (15%). The neutral sugar composition was identified by gas chromatography as mannose, fucose, glucose, and galactose in a 6.7:0.2:0.1:0.1 ratio. The molecular weight of purified EPS was estimated to be 1.0-3.8 x 10(5) Dalton, and the distribution of the molecular weight was very homogeneous (polydispersity index = 1.32). The EPS solution showed a characteristic of pseudoplastic non-Newtonian fluid at a concentration >2.0% in distilled water. The maximum EPS production was obtained when the strain was grown on glucose (30 g/L). Ammonium sulfate was the best suitable nitrogen source for EPS production. The highest yield of EPS was obtained at a carbon to nitrogen ratio of 15. The EPS synthesis was activated at the acidic range of pH 3.0-5.0 and increased when the pH of the culture broth decreased naturally to <2.0 during the fermentation. When the yeast was grown on glucose (30 g/L) and ammonium sulfate (2 g/L) at 22 degrees C at an initial pH of 4.0, EPS production was maximized (4.0 g/L), and the glucose-based production yield coefficient and carbon-based production yield coefficient were 0.30 g of EPS/g of glucose and 0.34 g (carbon of EPS)/g (carbon of glucose), respectively.

CTCF-binding sites flank CTG/CAG repeats and form a methylation-sensitive insulator at the DM1 locus

An expansion of a CTG repeat at the DM1 locus causes myotonic dystrophy (DM) by altering the expression of the two adjacent genes, DMPK and SIX5, and through a toxic effect of the repeat-containing RNA. Here we identify two CTCF-binding sites that flank the CTG repeat and form an insulator element between DMPK and SIX5. Methylation of these sites prevents binding of CTCF, indicating that the DM1 locus methylation in congenital DM would disrupt insulator function. Furthermore, CTCF-binding sites are associated with CTG/CAG repeats at several other loci. We suggest a general role for CTG/CAG repeats as components of insulator elements at multiple sites in the human genome.

The behavior of a poly(aniline) solid contact pH selective electrode based on N,N,N',N'-tetrabenzylethanediamine ionophore

A hydrogen ion-selective solid-contact electrode based on N,N,N',N'-tetrabenzylethanediamine has shown the best Nernstian slope and selectivity and the widest response range in a Tris buffered pH sample solution. Its linear dynamic range was pH 3.50-11.94, and the Nernstian slope showed 52.1 mV/pH (at 20 +/- 0.2 degrees C). When it was directly applied to human whole blood (in pH range 6.0-8.5) we could obtain the same satisfying results. This electrode continuously contacted a Tris 7.47 buffered solution, human whole blood and a hydrofluoric acid solution for one month without any loss of performance. Also, hydrofluoric acid did not influence the surface of this electrode, and thus it was maintained without showing any changes in potentials after being used in a hydrofluoric acid solution. The standard deviation in the determined e.m.f. differences was 1.5 mV (N = 5) for Tris buffer solutions of pH 6.5 and 1.1 mV at a Tris buffer solutions of pH 8.5. The 90% response time of the electrodes obtained by injecting of hydrochloric acid into the Tris buffer sample solution was less than 10 s. Especially, in the this paper, with these potential response characteristics of hydrogen ion selective poly(aniline) solid contact electrode, we have also presented the pH response mechanism of this electrode and the role of poly(aniline) and a doped anion in a poly(aniline) layer.

Metabolic characteristics and prevalence of osteoporosis among women in Tae-An area

Understanding the metabolic changes in women is one of the important ways to prevent and treat osteoporosis. To reveal the metabolic characteristics of 289 healthy women aged between 35-65 yr in Tae-An, Korea we evaluated the association between bone mass assessed by broadband ultrasound attenuation (BUA) using quantitative ultrasound 2 (QUS2) and various parameters such as age, body mass index, serum levels of alkaline phosphatase, calcium, phosphorus, parathyroid hormone, 25(OH)D, and urinary ratios of calcium/creatinine and deoxypyridinoline (Dpyd)/creatinine. Among the subjects, 3.0% were osteoporotic, and 40.9% were osteopenic. When the subjects were classified according to their years since menopause (YSM) and age, the prevalence of osteoporosis increased along with an increase of YSM and age. Bone turnover markers such as serum alkaline phosphatase and fasting urinary Dpyd/creatinine were significantly higher in the group with low bone mass than in the normal group. In summary, this study shows, by use of biochemical markers of bone turnover and QUS2, the prevalence of osteoporosis in women aged between 35-65 in Tae-An was 3.0% and the risk of low bone mass increased with the bone turnover markers.

Flow cytometric evaluation on the age-dependent changes of testicular DNA contents in rats

An age-dependent cellular change of DNA contents in the testis of Sprague-Dawley rats was investigated by flow-cytometric method. Testicular cell suspensions at the age of 4, 5, 6, 7, 8, 10, 12, 16 and 26 weeks were prepared and stained with propidium iodide. The relative proportions in the number of mature and immature haploid (1n), diploid (2n), S-phase and tetraploid (4n) cells were calculated. The proportion in the number of mature haploid cells was sharply increased to the age of 10 weeks (about 38%), thereafter increased slightly to the level of 42% at the age of 26 weeks. The proportion of immature haploid cells was dramatically increased to the age of 6 weeks, then maintained at the level of 20 to 30% thereafter. The proportion of diploid cells was 64% at the age of 4 weeks, then decreased gradually through the age of 26 weeks. The proportion of S-phase cells was increased to the age of 4 weeks, then maintained at a plateau level to the age of 26 weeks. The proportion of tetraploid cells were about 26% at the age of 4 weeks, then decreased gradually to the age of 26 weeks. These results suggest that the proportions of testicular cells may depend on the age of the rat and that the flow cytometric method may be useful in the evaluation of the spermatogenic status with regard to accuracy and sensitivity.

Multi-facet expressions of adenylate cyclase isoforms in B16-F10 melanoma cells differentiated by forskolin treatment

The terminal differentiation of malignant melanoma cells is known to be induced by activating cAMP signaling pathway with alpha-MSH or cAMP analogues. However, sustained activation of cAMP signaling system that induces the differentiation of melanoma cells, also induces the desensitization of the pathway at the receptor level. Nevertheless, the adaptation of adenylate cyclase (AC) expression by sustained activation of cAMP signaling system has not been clearly understood. This study was performed to examine whether the sustained activation of cAMP system induce changes in the expression AC isoforms as an adaptation mechanism. Treatment of B16/F10 murine melanoma cells with 100 mM forskolin for 6 days resulted in differentiation, melanin accumulation and increased expression of tyrosine hydroxylase mRNA. In the forskolin-treated melanoma cells, change in expression of various AC isoform at the transcription level was detected by reverse-transcription polymerase chain reaction (RT-PCR). Expression of AC isoform mRNA: ACI, III, VI, VII, and IX increased to the level of 196-392% of the control whereas the level of ACII was decreased by 30%. The cAMP concentration was increased both in basal and alpha-MSH stimulated cells, but the AC activity was decreased in the forskolin treated cells. Thus, these results suggest that sustained activation of cAMP system induces differential expression of AC isoforms, which results in increase of cAMP accumulation.

Right thoracotomy for mitral reoperation: analysis of technique and outcome

BACKGROUND

This report describes technical details of the right thoracotomy approach for mitral surgery, and analyzes our experience with this procedure for patients with a prior sternotomy. Three methods for myocardial management (hypothermic cardioplegic arrest, beating heart, and fibrillating heart) are compared.

METHODS

Records were abstracted of patients who had a right thoracotomy between January 1, 1992 and July 1, 1999 for mitral surgery after at least one prior sternotomy. Demographic, operative, and outcome data were collected for analysis. Telephone follow-up was used to measure postoperative New York Heart Association functional status.

RESULTS

Eighty-four patients (mean age 60 +/- 15 years) had reoperative mitral surgery via a right thoracotomy. Myocardial management included ventricular fibrillation in 10 patients, operation on the beating heart in 58 patients, and hypothermic blood cardioplegia arrest in 16 patients. The mean time in the operating room was 185 +/- 73 minutes, and the mean duration of cardiopulmonary bypass was 63 +/- 56 minutes. There were no perioperative strokes and the prevalence of death for patients who received cardioplegic arrest was significantly higher than the prevalence of death for patients who had mitral surgery with perfused fibrillating or beating heart techniques (p = 0.007; Fisher's exact test comparing risk-unadjusted mortality).

CONCLUSIONS

Right thoracotomy provides efficient exposure for reoperative mitral surgery. Mitral valve procedures on the fibrillating or beating heart are feasible in most patients and are at least as safe as surgery using cardioplegic arrest.

Differential changes in the expression of cyclic nucleotide phosphodiesterase isoforms in rat brains by chronic treatment with electroconvulsive shock

Electroconvulsive shock (ECS) has been suggested to affect cAMP signaling pathways to exert therapeutic effects. ECS was recently reported to increase the expression of PDE4 isoforms in rat brain, however, these studies were limited to PDE4 family in the cerebral cortex and hippocampus. Thus, for comprehensive understanding of how ECS regulates PDE activity, the present study was performed to determine whether chronic ECS treatment induces differential changes in the expression of all the PDE isoforms in rat brains. We analyzed the mRNA expression of PDE isoforms in the rat hippocampus and striatum using reverse transcription polymerase chain reaction. We found chronic ECS treatment induced differential changes in the expression of PDE isoform 1, 2, 3, 4, 5 and 7 at the rat hippocampus and striatum. In the hippocampus, the expression of PDE1A/B (694%), PDE4A (158%), PDE4B (323 %), and PDE4D (181%) isoforms was increased from the controls, but the expression of PDE2 (62.8%) and PDE7 (37.8%) decreased by chronic ECS treatment. In the striatum, the expression of PDE1A/B (179%), PDE4A (223%), PDE4B (171%), and PDE4D (327%) was increased by chronic ECS treatment with the concomitant decrease in the expression of PDE2 (78.4%) and PDE3A (67.1%). In conclusion, chronic ECS treatment induces differential changes in the expression of most PDE isoforms including PDE1, PDE2, PDE3, PDE4, PDE5, and PDE7 in the rat hippocampus and striatum in an isoform- and brain region-specific manner. Such differential change is suggested to play an important role in regulation of the activity of PDE and cAMP system by ECS.

Mice deficient in Six5 develop cataracts: implications for myotonic dystrophy

Expansion of a CTG trinucleotide repeat in the 3' UTR of the gene DMPK at the DM1 locus on chromosome 19 causes myotonic dystrophy, a dominantly inherited disease characterized by skeletal muscle dystrophy and myotonia, cataracts and cardiac conduction defects. Targeted deletion of Dm15, the mouse orthologue of human DMPK, produced mice with a mild myopathy and cardiac conduction abnormalities, but without other features of myotonic dystrophy, such as myotonia and cataracts. We, and others, have demonstrated that repeat expansion decreases expression of the adjacent gene SIX5 (refs 7,8), which encodes a homeodomain transcription factor. To determine whether SIX5 deficiency contributes to the myotonic dystrophy phenotype, we disrupted mouse Six5 by replacing the first exon with a beta-galactosidase reporter. Six5-mutant mice showed reporter expression in multiple tissues, including the developing lens. Homozygous mutant mice had no apparent abnormalities of skeletal muscle function, but developed lenticular opacities at a higher rate than controls. Our results suggest that SIX5 deficiency contributes to the cataract phenotype in myotonic dystrophy, and that myotonic dystrophy represents a multigenic disorder.

Ligation of ICAM-1 molecules inhibits target cell-induced granule exocytosis of IL-12-activated natural killer cells

The importance of cell adhesion molecules such as ICAM-1 is emphasized in cell-to-cell interactions that are critical in the generation of effective immune reactions. In this study, the involvement of ICAM-1 in natural killer (NK) cell activities was characterized in IL-12-activated human NK cells. To address the question of whether ligation of ICAM-1 molecules can modulate NK cell cytolytic activities, a 4-h (51)Cr-release assay was performed after pretreatment of NK cells with R6.5 mAb (anti-human ICAM-1 mAb). Ligation of membrane ICAM-1 molecules significantly inhibited IL-12-enhanced NK cytotoxicity against K562, and the pretreatment of neutralizing soluble ICAM-1 with R6.5 mAb blocked this inhibitory effect. The involvement of Ca(2+)-dependent granular exocytosis was evaluated. BLT esterase assay demonstrated that the ligation of ICAM-1 molecules inhibited granular exocytosis of NK cells. Additionally, the ICAM-1-mediated inhibition of Ca(2+) flux in NK cells was detected using Fluo-3AM, while the pretreatment of NK cells with R6.5 mAb did not affect conjugate formation between NK and K562 cells. Collectively, these results suggest that the signals transduced from ICAM-1 molecules might be sufficient to induce inhibitory effects on NK cells.