Effect of growth hormone replacement therapy on plasma diacron-reactive oxygen metabolites and endothelial function in Japanese patients: The GREAT clinical study.

Patients with growth hormone deficiency (GHD) have an increased risk of atherosclerosis and vascular mortality. Evidence suggests that endothelial dysfunction is involved in all stages of atherogenesis. This study examined the effect of growth hormone (GH) replacement therapy on diacron-reactive oxygen metabolites (d-ROMs) and endothelial function in Japanese patients with GHD, using peripheral arterial tonometry. This was an open-label, prospective, case-control study. Nine patients with GHD who had not previously received any GH replacement therapy were enrolled. The following parameters were evaluated at baseline (before treatment), and after 24 weeks of GH replacement therapy: endothelial function using the reactive hyperemia index (RHI; EndoPAT® system), d-ROMs, blood pressure, and fasting lipid levels. Plasma GH and insulin-like growth factor-1 (IGF-1) levels were measured at baseline and after 24 weeks of GH replacement therapy. We also enrolled eight controls with pituitary disease but no GH deficiency. Over 24 weeks of GH replacement therapy, the serum IGF-1 levels normalized with significant improvement in the RHI (from 1.65 ± 0.33 to 1.92 ± 0.26, p < 0.05) and decreased d-ROM levels (from 356.8 ± 64.1 to 303.1 ± 43.3 U.CARR, p < 0.05). There were no significant improvements in the RHI or d-ROM levels in controls. GH replacement therapy in Japanese patients with GHD may be mediated by the reduced oxidative stress and the d-ROMs associated with the treatment.

Efficacy of Additional Canagliflozin Administration to Type 2 Diabetes Patients Receiving Insulin Therapy: Examination of Diurnal Glycemic Patterns Using Continuous Glucose Monitoring (CGM).

INTRODUCTION: The efficacy of administering a sodium-glucose cotransporter 2 inhibitor during insulin therapy has not been established. In this study, we examined its effects based on diurnal glycemic patterns using continuous glucose monitoring (CGM). METHODS: The subjects were 15 patients who had received insulin therapy for 1 year or more. A CGM device was attached to all subjects for 1 week. The administration of canagliflozin at 100 mg was started 4 days after attachment. The mean glucose concentrations, standard deviation (SD), mean amplitude of glycemic excursions (MAGE), mean of daily difference of blood glucose (MODD), and area under the curve (AUC) (≥180, <70 mg h/dL) after the start of administration were compared with the pretreatment values. In addition, we compared changes in the number of insulin units between basal and bolus insulin. Furthermore, we investigated the influence of canagliflozin on oxidative stress markers and cytokines using 8-hydroxy-2'-deoxyguanosine (8-OHdG), tumor necrosis factor-α (TNF-α), and adiponectin as parameters. RESULTS: The mean glucose concentrations decreased from 161.1 to 139.1 mg/dL (P < 0.01). The SD decreased from 36.5 to 29.6 mg/dL (P = 0.05). The MAGE decreased from 89.2 to 77.4 mg/dL (P < 0.01), and the MODD decreased from 34.3 to 25.5 mg/dL (P < 0.05). All parameters showed significant improvements in diurnal changes. AUC of ≥180, i.e., the total area of blood glucose levels at or above 180 on the blood glucose curve of CGM, decreased from 339.1 to 113.6 mg/dL (P < 0.05). AUC of <70, i.e., the total area of blood glucose levels below 70 on the blood glucose curve of CGM, slightly decreased from 1.6 to 0.3 mg/dL (P = 0.08). The total number of basal insulin units decreased from 128 to 76, and that of bolus insulin decreased from 266 to 154; the dose of insulin could be markedly decreased. In addition, the mean 8-OHdG level decreased from 11.4 to 10.8 ng/mg Cre (P < 0.05), and the mean TNF-α level decreased from 2.31 to 1.79 pg/mL (P = 0.10). The mean adiponectin level increased from 5.01 to 5.53 µg/mL (P < 0.05). CONCLUSION: Canagliflozin improved blood glucose changes in type 2 diabetes using insulin. In addition, the results suggest its antioxidant actions. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN no. 000019429).

Screening of a composite library of clinically used drugs and well-characterized pharmacological compounds for cystathionine ß-synthase inhibition identifies benserazide as a drug potentially suitable for repurposing for the experimental therapy of colon cancer.

Cystathionine-ß-synthase (CBS) has been recently identified as a drug target for several forms of cancer. Currently no potent and selective CBS inhibitors are available. Using a composite collection of 8871 clinically used drugs and well-annotated pharmacological compounds (including the LOPAC library, the FDA Approved Drug Library, the NIH Clinical Collection, the New Prestwick Chemical Library, the US Drug Collection, the International Drug Collection, the 'Killer Plates' collection and a small custom collection of PLP-dependent enzyme inhibitors), we conducted an in vitro screen in order to identify inhibitors for CBS using a primary 7-azido-4-methylcoumarin (AzMc) screen to detect CBS-derived hydrogen sulfide (H2S) production. Initial hits were subjected to counterscreens using the methylene blue assay (a secondary assay to measure H2S production) and were assessed for their ability to quench the H2S signal produced by the H2S donor compound GYY4137. Four compounds, hexachlorophene, tannic acid, aurintricarboxylic acid and benserazide showed concentration-dependent CBS inhibitory actions without scavenging H2S released from GYY4137, identifying them as direct CBS inhibitors. Hexachlorophene (IC50: ∼60µM), tannic acid (IC50: ∼40µM) and benserazide (IC50: ∼30µM) were less potent CBS inhibitors than the two reference compounds AOAA (IC50: ∼3µM) and NSC67078 (IC50: ∼1µM), while aurintricarboxylic acid (IC50: ∼3µM) was equipotent with AOAA. The second reference compound NSC67078 not only inhibited the CBS-induced AzMC fluorescence signal (IC50: ∼1µM), but also inhibited with the GYY4137-induced AzMC fluorescence signal with (IC50 of ∼6µM) indicative of scavenging/non-specific effects. Hexachlorophene (IC50: ∼6µM), tannic acid (IC50: ∼20µM), benserazide (IC50: ∼20µM), and NSC67078 (IC50: ∼0.3µM) inhibited HCT116 colon cancer cells proliferation with greater potency than AOAA (IC50: ∼300µM). In contrast, although a CBS inhibitor in the cell-free assay, aurintricarboxylic acid failed to inhibit HCT116 proliferation at lower concentrations, and stimulated cell proliferation at 300µM. Copper-containing compounds present in the libraries, were also found to be potent inhibitors of recombinant CBS; however this activity was due to the CBS inhibitory effect of copper ions themselves. However, copper ions, up to 300µM, did not inhibit HCT116 cell proliferation. Benserazide was only a weak inhibitor of the activity of the other H2S-generating enzymes CSE and 3-MST activity (16% and 35% inhibition at 100µM, respectively) in vitro. Benserazide suppressed HCT116 mitochondrial function and inhibited proliferation of the high CBS-expressing colon cancer cell line HT29, but not the low CBS-expressing line, LoVo. The major benserazide metabolite 2,3,4-trihydroxybenzylhydrazine also inhibited CBS activity and suppressed HCT116 cell proliferation in vitro. In an in vivo study of nude mice bearing human colon cancer cell xenografts, benserazide (50mg/kg/days.q.) prevented tumor growth. In silico docking simulations showed that benserazide binds in the active site of the enzyme and reacts with the PLP cofactor by forming reversible but kinetically stable Schiff base-like adducts with the formyl moiety of pyridoxal. We conclude that benserazide inhibits CBS activity and suppresses colon cancer cell proliferation and bioenergetics in vitro, and tumor growth in vivo. Further pharmacokinetic, pharmacodynamic and preclinical animal studies are necessary to evaluate the potential of repurposing benserazide for the treatment of colorectal cancers.

Cystathionine-beta-synthase inhibition for colon cancer: Enhancement of the efficacy of aminooxyacetic acid via the prodrug approach.

Colon cancer cells contain high levels of cystathionine-beta-synthase (CBS). Its product, hydrogen sulfide (H2S) promotes the growth and proliferation of colorectal tumor cells. In order to improve the antitumor efficacy of the prototypical CBS inhibitor aminooxyacetic acid (AOAA), we have designed and synthesized YD0171, a methyl ester derivative of AOAA. The antiproliferative effect of YD0171 exceeded the antiproliferative potency of AOAA in HCT116 human colon cancer cells. The esterase inhibitor paraoxon prevented the cellular inhibition of CBS activity by YD0171. YD0171 suppressed mitochondrial respiration and glycolytic function and induced G0/G1 arrest, but did not induce tumor cell apoptosis or necrosis. Metabolomic analysis in HCT116 cells showed that YD0171 affects multiple pathways of cell metabolism. The efficacy of YD0171 as an inhibitor of tumor growth was also tested in nude mice bearing subcutaneous HCT116 cancer cell xenografts. Animals were treated via subcutaneous injection of vehicle, AOAA (1, 3 or 9 mg/kg/day) or YD0171 (0.1, 0.5 or 1 mg/kg/day) for 3 weeks. Tumor growth was significantly reduced by 9 mg/kg/day AOAA, but not at the lower doses. YD0171 was more potent: tumor volume was significantly inhibited at 0.5 and 1 mg/kg/day. Thus, the in vivo efficacy of YD0171 is 9-times higher than that of AOAA. YD0171 (1 mg/kg/day) attenuated tumor growth and metastasis formation in the intracecal HCT116 tumor model. YD0171 (3 mg/kg/day) also reduced tumor growth in patient-derived tumor xenograft (PDTX) bearing athymic mice. YD0171 (3 mg/kg/day) induced the regression of established HCT116 tumors in vivo. A 5-day safety study in mice demonstrated that YD0171 at 20 mg/kg/day (given in two divided doses) does not increase plasma markers of organ injury, nor does it induce histological alterations in the liver or kidney. YD0171 caused a slight elevation in plasma homocysteine levels. In conclusion, the prodrug approach improves the pharmacological profile of AOAA; YD0171 represents a prototype for CBS inhibitory anticancer prodrugs. By targeting colorectal cancer bioenergetics, an emerging important hallmark of cancer, the approach exemplified herein may offer direct translational opportunities.

Regulation of Vascular Tone, Angiogenesis and Cellular Bioenergetics by the 3-Mercaptopyruvate Sulfurtransferase/H2S Pathway: Functional Impairment by Hyperglycemia and Restoration by DL-α-Lipoic Acid.

Hydrogen sulfide (H2S), as a reducing agent and an antioxidant molecule, exerts protective effects against hyperglycemic stress in the vascular endothelium. The mitochondrial enzyme 3-mercaptopyruvate sulfurtransferase (3-MST) is an important biological source of H2S. We have recently demonstrated that 3-MST activity is inhibited by oxidative stress in vitro and speculated that this may have an adverse effect on cellular homeostasis. In the current study, given the importance of H2S as a vasorelaxant, angiogenesis stimulator and cellular bioenergetic mediator, we first determined whether the 3-MST/H2S system plays a physiological regulatory role in endothelial cells. Next, we tested whether a dysfunction of this pathway develops during the development of hyperglycemia and µmol/L to diabetes-associated vascular complications. Intraperitoneal (IP) 3-MP (1 mg/kg) raised plasma H2S levels in rats. 3-MP (10 1 mmol/L) promoted angiogenesis in vitro in bEnd3 microvascular endothelial cells and in vivo in a Matrigel assay in mice (0.3-1 mg/kg). In vitro studies with bEnd3 cell homogenates demonstrated that the 3-MP-induced increases in H2S production depended on enzymatic activity, although at higher concentrations (1-3 mmol/L) there was also evidence for an additional nonenzymatic H2S production by 3-MP. In vivo, 3-MP facilitated wound healing in rats, induced the relaxation of dermal microvessels and increased mitochondrial bioenergetic function. In vitro hyperglycemia or in vivo streptozotocin diabetes impaired angiogenesis, attenuated mitochondrial function and delayed wound healing; all of these responses were associated with an impairment of the proangiogenic and bioenergetic effects of 3-MP. The antioxidants DL-α-lipoic acid (LA) in vivo, or dihydrolipoic acid (DHLA) in vitro restored the ability of 3-MP to stimulate angiogenesis, cellular bioenergetics and wound healing in hyperglycemia and diabetes. We conclude that diabetes leads to an impairment of the 3-MST/H2S pathway, and speculate that this may contribute to the pathogenesis of hyperglycemic endothelial cell dysfunction. We also suggest that therapy with H2S donors, or treatment with the combination of 3-MP and lipoic acid may be beneficial in improving angiogenesis and bioenergetics in hyperglycemia.

Regulation of mitochondrial bioenergetic function by hydrogen sulfide. Part I. Biochemical and physiological mechanisms.

Until recently, hydrogen sulfide (H2 S) was exclusively viewed a toxic gas and an environmental hazard, with its toxicity primarily attributed to the inhibition of mitochondrial Complex IV, resulting in a shutdown of mitochondrial electron transport and cellular ATP generation. Work over the last decade established multiple biological regulatory roles of H2 S, as an endogenous gaseous transmitter. H2 S is produced by cystathionine γ-lyase (CSE), cystathionine ß-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). In striking contrast to its inhibitory effect on Complex IV, recent studies showed that at lower concentrations, H2 S serves as a stimulator of electron transport in mammalian cells, by acting as a mitochondrial electron donor. Endogenous H2 S, produced by mitochondrially localized 3-MST, supports basal, physiological cellular bioenergetic functions; the activity of this metabolic support declines with physiological aging. In specialized conditions (calcium overload in vascular smooth muscle, colon cancer cells), CSE and CBS can also associate with the mitochondria; H2 S produced by these enzymes, serves as an endogenous stimulator of cellular bioenergetics. The current article overviews the biochemical mechanisms underlying the stimulatory and inhibitory effects of H2 S on mitochondrial function and cellular bioenergetics and discusses the implication of these processes for normal cellular physiology. The relevance of H2 S biology is also discussed in the context of colonic epithelial cell physiology: colonocytes are exposed to high levels of sulfide produced by enteric bacteria, and serve as a metabolic barrier to limit their entry into the mammalian host, while, at the same time, utilizing it as a metabolic 'fuel'.

A crossover study of rosuvastatin and pitavastatin in patients with type 2 diabetes.

INTRODUCTION: The effects of a low dose of rosuvastatin (ROS) and pitavastatin (PIT) on lipid profiles and inflammation markers were assessed in subjects with type 2 diabetes mellitus. METHODS: A total of 90 Japanese type 2 diabetes patients with hyperlipidemia (low-density lipoprotein cholesterol [LDL-C] ≥140 mg/dL) were enrolled in this study. They were randomly assigned to four groups with open-label treatment with ROS (2.5 mg daily) or PIT (2 mg daily); two groups were sequentially treated with both drugs, with crossover of medication after 12 weeks, and the other two groups underwent treatment with either ROS or PIT for 24 weeks. The primary endpoints were the percentage changes in LDL-C, high-density lipoprotein cholesterol (HDL-C) and triglyceride, and the LDL-C/HDL-C ratio. RESULTS: Both ROS and PIT lowered LDL-C and triglyceride, and increased HDL-C. In particular, significantly greater reduction in LDL-C was seen with ROS (-44.1%) than with PIT (-36.9%, P<0.01) in the crossover group from ROS to PIT, and the same result was detected in the crossover group from PIT (-34.8%) to ROS (-44.7%). The ratio of LDL-C/HDL-C was significantly reduced with ROS treatment (from 3.45 to 1.85) compared with that with PIT (from 3.45 to 2.22, P<0.01). Both ROS and PIT lowered plasma levels of high-sensitivity C-reactive protein (hsCRP), tumor necrosis factor (TNF)-alpha, and plasminogen activator inhibitor-1 (PAI-1). In addition, the hsCRP level with the administration of ROS was significantly improved compared with the administration of PIT. There was no significant correlation between changes in LDL-C and hsCRP, TNF-alpha, and PAI-1 levels. ROS and PIT did not have an adverse effect on glycemic control in type 2 diabetes patients. CONCLUSION: Therapy with both statins improved lipid profiles and reduced proinflammatory responses; however, 2.5 mg of ROS have a potent LDL-C-lowering and hsCRP-lowering effect compared with 2 mg of PIT in patients with diabetes.

Effect of raloxifene on serum lipids for type 2 diabetic menopausal women with or without statin treatment.

OBJECTIVE: Our aim was to investigate the effect of 1-year treatment with raloxifene, a selective estrogen receptor modulator, on plasma lipid profiles in Japanese postmenopausal type 2 diabetic patients. SUBJECTS AND METHODS: A total of 43 Japanese women with postmenopausal osteoporosis and type 2 diabetes with serum low-density lipoprotein cholesterol (LDL-C) <3.59 mmol/l, serum triglyceride <1.68 mmol/l and serum high-density lipoprotein cholesterol (HDL-C) >1.03 mmol/l, who took 60 mg/day of raloxifene for 12 months, were enrolled. For analysis, they were divided into 2 groups: nonhyperlipidemia (n = 23) and hyperlipidemia treated with statin (n = 20). RESULTS: Raloxifene treatment significantly induced a mean reduction in serum LDL-C from 2.90 to 2.36 and 2.67 mmol/l in the nonhyperlipidemia and statin-treated group, respectively. However, the reduction ratio of serum LDL-C showed a significant difference in the nonhyperlipidemia group (17%) compared to the statin-treated group (7%; p = 0.03). Although serum HDL-C showed an increase in both groups (from 1.45 to 1.58 vs. from 1.40 to 1.47 mmol/l), the increase ratio of serum HDL-C was not significant between the two groups. Raloxifene administration showed 15% reduction in the nonhyperlipidemia group (p = 0.02) and 13% reduction in the statin-treated group (p = 0.02) of urinary N-telopeptide of type I collagen. No significant change in blood HbA(1c) was observed in either group. CONCLUSION: The administration of raloxifene to type 2 diabetic women showed favorable efficacy on serum lipid profiles, particularly in patients without statin treatment.

18O-labeling quantitative proteomics using an ion trap mass spectrometer.

We describe a method for simultaneous identification and quantitation of proteins within complex mixtures. The method consists of 18O-labeling, a simple stable isotope-coding that requires merely enzymatic digestion in 18O-water, in combination with a capillary-liquid chromatography electrospray ion-trap mass spectrometer. In a separate experiment using the same sample and a spike test, we demonstrate that the difference ration was calculated accurately using the 18O-labeling method even if the protein was part of a complex mixture. Our data also suggest that the accuracy of the quantitation can be improved by averaging the difference ratios of several peptides. In comparing our method with the isotope-coded affinity tag (ICAT) method, we show that the 18O-labeling method has the advantages of better recovery and fewer isotope effects. Therefore, the 18O-labeling method is a powerful tool for large-scale proteomics applications.

Ubiquitination-mediated regulation of biosynthesis of the adhesion receptor SHPS-1 in response to endoplasmic reticulum stress.

Misfolding of proteins during endoplasmic reticulum (ER) stress results in the formation of cytotoxic aggregates. The ER-associated degradation pathway counteracts such aggregation through the elimination of misfolded proteins by the ubiquitin-proteasome system. We now show that SHP substrate-1 (SHPS-1), a transmembrane glycoprotein that regulates cytoskeletal reorganization and cell-cell communication, is a physiological substrate for the Skp1-Cullin1-NFB42-Rbx1 (SCF(NFB42)) E3 ubiquitin ligase, a proposed mediator of ER-associated degradation. SCF(NFB42) mediated the polyubiquitination of immature SHPS-1 and its degradation by the proteasome. Ectopic expression of NFB42 both suppressed the formation of aggresome-like structures and the phosphorylation of the translational regulator eIF2alpha induced by overproduction of SHPS-1 as well as increased the amount of mature SHPS-1 at the cell surface. An NFB42 mutant lacking the F box domain had no such effects. Our results suggest that SCF(NFB42) regulates SHPS-1 biosynthesis in response to ER stress.