JTT-654, an 11-beta hydroxysteroid dehydrogenase type 1 inhibitor, improves hypertension and diabetic kidney injury by suppressing angiotensinogen production.

11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) plays an important role in regulating the expression of glucocorticoid actions in target tissues. Overexpression of 11ß-HSD1 in mouse adipose tissue causes a metabolic syndrome-like phenotype, leading to hypertension. Although, many 11ß-HSD1 inhibitors have been studied, few have shown a clear ameliorative effect against hypertension. We investigated whether JTT-654, a novel 11ß-HSD1 inhibitor, ameliorated hypertension and elucidated the underlying mechanisms. JTT-654 showed inhibitory effects on angiotensinogen production in cortisone-treated 3T3-L1 adipocytes and in a rat model. JTT-654 improved hypertension not only in cortisone-treated rats and spontaneously hypertensive rats (SHR), but also in SHR/NDmcr-cp rats. In the SHR study, JTT-654 and losartan showed the same degree of antihypertensive efficacy. In addition, JTT-654 ameliorated diabetic nephropathy by suppressing renal angiotensinogen production in SHR/NDmcr-cp rats. These effects of JTT-654 were independent of its insulin-sensitizing effects, and similar effects were not observed for pioglitazone, an insulin sensitizer. Moreover, JTT-654 did not affect normotension or hypothalamus-pituitary-adrenal (HPA) axis function in normal Sprague-Dawley rats. Our results indicate that JTT-654 ameliorates hypertension and diabetic nephropathy by inhibiting 11ß-HSD1 in the adipose tissue, liver, and kidney.

An 11-Beta Hydroxysteroid Dehydrogenase Type 1 Inhibitor, JTT-654 Ameliorates Insulin Resistance and Non-obese Type 2 Diabetes.

11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) is the only enzyme that converts inactive glucocorticoids to active forms and plays an important role in the regulation of glucocorticoid action in target tissues. JTT-654 is a selective 11ß-HSD1 inhibitor and we investigated its pharmacological properties in cortisone-treated rats and non-obese type 2 diabetic Goto-Kakizaki (GK) rats because Asians, including Japanese, are more likely to have non-obese type 2 diabetics. Systemic cortisone treatment increased fasting plasma glucose and insulin levels and impaired insulin action on glucose disposal rate and hepatic glucose production assessed by hyperinsulinemic-euglycemic clamp, but all these effects were attenuated by JTT-654 administration. Cortisone treatment also reduced basal and insulin-stimulated glucose oxidation in adipose tissue, increased plasma glucose levels after administration of the pyruvate, the substrate of gluconeogenesis, and increased liver glycogen content. Administration of JTT-654 also inhibited all of these effects. Cortisone treatment decreased basal and insulin-stimulated 2-deoxy-D-[1-3H]-glucose uptake in 3T3-L1 adipocytes and increased the release of free fatty acids and glycerol, a gluconeogenic substrate, from 3T3-L1 adipocytes, and JTT-654 significantly attenuated these effects. In GK rats, JTT-654 treatment significantly reduced fasting plasma glucose and insulin levels, enhanced insulin-stimulated glucose oxidation in adipose tissue, and suppressed hepatic gluconeogenesis as assessed by pyruvate administration. These results demonstrated that glucocorticoid was involved in the pathology of diabetes in GK rats, as in cortisone-treated rats, and that JTT-654 ameliorated the diabetic conditions. Our results suggest that JTT-654 ameliorates insulin resistance and non-obese type 2 diabetes by inhibiting adipose tissue and liver 11ß-HSD1.

Identification of Novel Phospholipid Transfer Protein Inhibitors by High-Throughput Screening.

Atherogenesis has been recognized as a risk factor for lethal cardiovascular diseases. Plasma low-density lipoprotein levels are correlated to the occurrence of atherosclerosis, and their control is critical for both the prevention and treatment of these diseases. Phospholipid transfer protein (PLTP) is one of the key regulators of lipoprotein metabolism; PLTP-deficient mice exhibit decreased apolipoprotein B (apoB)-containing lipoprotein secretion and atherosclerosis, indicating the validity of PLTP as a promising therapeutic target. Here, we demonstrate a high-throughput screening (HTS) method to identify a novel chemotype of PLTP inhibitors. Instead of using recombinant proteins, we used human plasma as a source of enzymes in the first screening, so as to efficiently exclude promiscuous inhibitors. The selected compounds were further confirmed to target PLTP both biochemically and biophysically and were shown to inhibit apoB secretion from hepatic cells with no apparent toxicity. We believe that our approach is suitable for filtering out nonspecific inhibitors at an earlier stage of screening campaigns and that these compounds should have potential to be developed into drugs to treat dyslipidemia.

Induction by staurosporine of hepatocyte growth factor production in human skin fibroblasts independent of protein kinase inhibition.

Staurosporine is one of the most potent and well known inhibitors of protein kinases, and it is often used to study the involvement of protein kinases in signal transduction pathways. We now report that staurosporine can induce the production of hepatocyte growth factor (HGF) independently of protein kinase inhibition. Staurosporine markedly stimulated the production of HGF in various cell types, including human skin fibroblasts. Its effect was accompanied by up-regulation of HGF gene expression. The inhibition of protein kinases appears not to be involved in staurosporine-induced HGF production, because other protein kinase inhibitors, K-252a, H-7, GF 109203X and genistein, had no HGF-inducing activity. UCN-01, 7-hydroxystaurosporine, which differs from staurosporine only in its aglycone moiety, also showed HGF-inducing activity, and inactive K-252a differs from staurosporine only in its sugar moiety. These results indicate that the sugar moiety, a six-atom ring structure, is important in the HGF-inducing activity of staurosporine. Experiments were then carried out to determine whether the characteristics of staurosporine-induced HGF production have similarities to those of HGF production stimulated by other HGF inducers. The effect of staurosporine like that of 8-bromo-cAMP and that of cholera toxin was marked in human skin fibroblasts from all four different sources, whereas the effects of epidermal growth factor and phorbol 12-myristate 13-acetate were variable depending on cells. The net increase in HGF production induced by staurosporine was not reduced in protein kinase C-depleted human skin fibroblasts. Moreover, synergistic induction of HGF was detected between staurosporine and interferon-gamma as well as between 8-bromo-cAMP and interferon-gamma. Staurosporine, however, did not increase intracellular cAMP levels in human skin fibroblasts. These results indicate that staurosporine induced HGF in different cell types via a signaling pathway similar to the cAMP-mediated pathway without increasing cAMP levels.

Effect of JTT-705 on cholesteryl ester transfer protein and plasma lipid levels in normolipidemic animals.

This study evaluated JTT-705, S-[2-([[1-(2-ethylbutyl)cyclohexyl]carbonyl]amino)phenyl]2-methylpropanethioate, as a cholesteryl ester transfer protein (CETP) inhibitor in several animal species. In vitro, JTT-705 inhibited plasma CETP activities of humans, rabbits, hamsters, cynomolgus monkeys and marmosets with IC(50) values of 5.5, 1.0, 11.7, 2.4 and 6.3 microM, respectively. The thiol form (JTP-25203) also inhibited those activities with IC(50) values of 2.8, 0.44, 0.52, 1.3 and 1.1 microM, respectively. Following oral administration to normolipidemic animals (rabbits, hamsters and marmosets), JTT-705 reduced plasma CETP activity, increased high density lipoprotein cholesterol (HDL-cholesterol), and decreased the ratio of non-HDL-cholesterol to HDL-cholesterol (atherogenic index) in all species. In marmosets, JTT-705 increased slow alpha-migrating lipoprotein (apolipoprotein E-rich HDL) in agarose gel electrophoresis, indicating that HDL metabolism in JTT-705-treated marmosets is similar to that in CETP-deficient humans. These results indicate that JTT-705 can be expected to inhibit plasma CETP activity and improve plasma lipoprotein profiles in a wide range of animal species, including humans.