Won Hoon Jung

Anti-diabetic and anti-adipogenic effects of a novel selective 11β-hydroxysteroid dehydrogenase type 1 inhibitor, 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone (KR-66344)

The selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential for treating type 2 diabetes mellitus and metabolic syndrome. In the present study, we investigated the anti-diabetic and anti-adipogenic effects of 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone (KR-66344), as a 11β-HSD1 inhibitor; we also investigated the underlying molecular mechanisms in the cortisone-induced 3T3-L1 adipogenesis model system and C57BL/6-Lep(ob/ob) mice. KR-66344 concentration-dependently inhibited 11β-HSD1 activity in human liver microsome, mouse C2C12 myotube and human SW982 cells. In the C57BL/6-Lep(ob/ob) mice study, the administration of KR-66344 (200mg/kg/d, orally for 5 days) improved the glucose intolerance as determined by the oral glucose tolerance test, in which the area under the curve (AUC) of the plasma glucose concentration was significantly reduced by 27% compared with the vehicle treated group. Further, KR-66344 suppressed adipocyte differentiation on cortisone-induced adipogenesis in 3T3-L1 cells is associated with the suppression of the cortisone-induced mRNA levels of FABP4, G3PD, PPARγ2 and Glut4, and 11β-HSD1 expression and activity. Our results additionally demonstrate evidence showing that KR-66344 improved glycemic control and inhibited adipogenesis via 11β-HSD1 enzyme activity. Taken together, these results may provide evidence of the therapeutic potential of KR-66344, as a 11β-HSD1 inhibitor, in obesity and type 2 diabetes patients with metabolic syndrome.

Leptin inhibits rosiglitazone-induced adipogenesis in murine primary adipocytes.

Leptin mainly acts on the hypothalamus in the brain, in which it regulates food intake and energy expenditure. However, the direct effects of leptin on adipocytes have been controversial in the cellular level. In this study, the effects of leptin on rosiglitazone-induced adipocyte differentiation were investigated in the primary preadipocytes prepared from subcutaneous fat tissues of C57BL/6-Lep(ob/ob) mouse. We found that acute and prolonged treatment of leptin on preadipocytes inhibited the rosiglitazone-induced transcription factor expression and adipocyte differentiation, respectively, accompanied with decreased expression of PPARgamma and aP2. Either PD98059, an ERK inhibitor or fludarabine, a STAT1 inhibitor restored leptin-inhibited PPARgamma expression and subsequent lipid accumulation, but inhibitors for PI-3K (LY294002) and for STAT3 (piceatannol) did not. Furthermore, leptin decreased PPARgamma expression also in fully differentiated adipocytes, which was reversed by either PD98059 or fludarabine. Taken together, these data suggest that leptin has a direct inhibitory effect on the rosiglitazone-induced adipocyte differentiation and PPARgamma expression, in which ERK1/2 MAP kinase and JAK/STAT1 signaling pathways are involved.

Synthesis and biological evaluation of aminobenzimidazole derivatives with a phenylcyclohexyl acetic acid group as anti-obesity and anti-diabetic agents.

A series of benzimidazole derivatives with a phenylcyclohexyl acetic acid group as DGAT-1 inhibitors was developed. Among the benzimidazole series, compound 5k showed submicromolar in vitro activity toward human and mouse DGAT-1, good selectivity toward DGAT-2, human liver metabolic stability, and pharmacokinetic (PK) and safety profiles such as hERG, CYP and acute toxicity. Additionally, 5k showed good in vivo efficacy in 4weeks study with DIO mouse model.

Phosphatase and Tensin Homolog Deleted on Chromosome 10 Suppression Is an Important Process in Peroxisome Proliferator-Activated Receptor-γ Signaling in Adipocytes and Myotubes

Peroxisome proliferator-activated receptor-γ (PPARγ) activation enhances insulin sensitivity in type 2 diabetes mellitus. However, downstream mediators of PPARγ activation in adipocytes and myotubes, the most important cell types involved in glucose homeostasis, remained unclear. Here we show by using two synthetic PPARγ agonists (rosiglitazone and KR-62776, a novel PPARγ agonist) that phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a key downstream mediator of PPARγ signaling. The PPARγ agonists down-regulated PTEN expression, resulting in glucose uptake increase in differentiated 3T3-L1 adipocytes and C2C12 skeletal muscle cells. In both cells, PTEN knockdown increased glucose uptake, whereas overexpression abolished the agonist-induced effects. The effects of PPARγ agonists on PTEN expression and glucose uptake disappeared by pretreatment with a PPARγ antagonist or by knockdown of PPARγ expression. In vivo treatment of the agonists to C57BL/6J-ob/ob mice resulted in the reduction of PTEN level in both adipose and skeletal muscle tissues and decreased plasma glucose levels. Thus, these results suggest that PTEN suppression is a key mechanism of the PPARγ-mediated glucose uptake stimulation in insulin-sensitive cells such as adipocytes and skeletal muscle cells, thereby restoring glucose homeostasis in type 2 diabetes.

Carbenoxolone prevents the development of fatty liver in C57BL/6-Lep ob/ob mice via the inhibition of sterol regulatory element binding protein-1c activity and apoptosis

Carbenoxolone is the 3-hemisuccinate of glycyrrhetinic acid, the active principal of licorice (Glycyrrhiza glabra). It was reported that carbenoxolone improved glucose tolerance with increased insulin sensitivity in mice with high fat diet-induced obesity. In the present study, we elucidated the protective effect of carbenoxolone in fatty liver animal models of C57BL/6-Lep(ob/ob) mice through inhibition of hepatic lipogenesis and apoptosis. In addition, the potential mechanisms by which carbenoxolone could exert such protection were elucidated. Carbenoxolone was daily administrated by gavage for 28 days in C57BL/6 and C57BL/6-Lep(ob/ob) mice. Carbenoxolone prevented the plasma triglyceride and free fatty acid accumulation associated with the reduction of the expression of sterol regulatory element binding protein-1c, liver X receptor, fatty acid synthase and acethyl-CoA carboxylase in the livers of C57BL/6-Lep(ob/ob) mice. Carbenoxolone also prevented hepatic injury through anti-apoptotic action in the livers of C57BL/6-Lep(ob/ob) mice, accompanied by increased Bcl-2 expression and suppressed Bax and cytochrome c expression. As a mechanism, increased inflammatory cytokine expressions were inhibited by carbenoxolone in the fatty livers of C57BL/6-Lep(ob/ob) mice. Furthermore, carbenoxolone inhibited free fatty acid (oleate/palmitate) induced reactive oxygen species formation and reversed free fatty acid induced mitochondrial membrane depolarization in HepG2 cells. Carbenoxolone prevents the development of fatty liver by inhibiting sterol regulatory element binding protein-1c expression and activity with an anti-apoptotic mechanism via the inhibition of inflammatory cytokine and reactive oxygen species formation in the livers of C57BL/6-Lep(ob/ob) mice. It is suggested that carbenoxolone prevents the development and progression of fatty liver disease in patients with insulin resistance.

Synthesis and biological evaluation of cyclic sulfamide derivatives as 11β-hydroxysteroid dehydrogenase 1 inhibitors.

A new series of cyclic sulfamide derivatives were synthesized and evaluated for their ability to inhibit 11β-HSD1. Among this series, 18e showed good in vitro activity toward human 11β-HSD1, selectivity against 11β-HSD2, microsomal stability, and pharmacokinetic and safety profiles (hERG, CYP, and acute toxicity). Additionally, 18e exhibited good in vivo efficacy in rat and monkey models.

Selective inhibition of activated stellate cells and protection from carbon tetrachloride-induced liver injury in rats by a new PPARγ agonist KR62776

Activated hepatic stellate cells (HSC) are the primary source of extracellular matrix proteins found in liver fibrosis/cirrhosis patients. Therefore, the prevention of HSC activation is an important strategy for treating severe liver injury. This study examined the effects of KR62776, a new peroxisome proliferator-activated receptor γ (PPARγ) agonist, on the rate of cell proliferation and expression of α-smooth muscle actin (α-SMA) in rat hepatic stellate HSC-T6 cells. In addition, its effects on the liver damage induced by carbon tetrachloride were investigated. KR62776 caused the apoptosis of activated HSC-T6 cells with the concomitant decrease in the α-smooth muscle actin levels in a time- and concentration-dependent manner. However, KR62776 did not cause the apoptosis of human HepG2 and rat McARH7777 hepatoma cells, suggesting that KR62776 has a specific effect on stellate cells. KR62776 increased the levels of Gadd45, p27, p21 and PPARγ proteins but decreased the cell cyclerelated proteins, such as cdk2, cyclin B and cyclin D1. These changes were reversed by BADGE, a specific PPARγ antagonist, indicating that the effects of KR62776 are, at least in part, PPARγ-dependent. In addition, KR62776 administration showed some protection against carbon tetrachloride-induced hepatocellular damage in rats. Overall, these results suggest that KR62776 may have potential in the chemoprevention of liver fibrosis/cirrhosis.

A novel 11β-HSD1 inhibitor improves diabesity and osteoblast differentiation

Selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential as treatment for osteoporosis as well as metabolic syndrome including type 2 diabetes mellitus. Here, we investigated the anti-diabetic, anti-adipogenic, and anti-osteoporotic activity of KR-67500, as a novel selective 11β-HSD1 inhibitor. Cellular 11β-HSD1 activity was tested based on a homogeneous time-resolved fluorescence method. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) levels were measured in diet-induced obese (DIO)-C57BL/6 mice administered KR-67500 (50  mg/kg per day, p.o.) for 28 days and, additionally, its anti-diabetic effect was evaluated by OGTT and ITT. The in vitro anti-adipogenic effect of KR-67500 was determined by Oil Red O Staining. The in vitro anti-osteoporotic activity of KR-67500 was evaluated using bone morphogenetic protein 2 (BMP2)-induced osteoblast differentiation and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation model systems. KR-67500 improved the in vivo glucose tolerance and insulin sensitivity in DIO-C57BL/6 mice. KR-67500 suppressed cortisone-induced differentiation of 3T3-L1 cells into adipocytes. KR-67500 enhanced BMP2-induced osteoblastogenesis in C2C12 cells and inhibited RANKL-induced osteoclastogenesis in mouse bone marrow-derived macrophages. KR-67500, a new selective 11β-HSD1 inhibitor, may provide a new therapeutic window in the prevention and/or treatment of type 2 diabetes, obesity, and/or osteoporosis.

Anti-diabetic and anti-adipogenic effects of a novel selective 11β-hydroxysteroid dehydrogenase type 1 inhibitor in the diet-induced obese mice

Glucocorticoid excess (Cushings syndrome) causes metabolic syndrome such as visceral obesity, insulin resistance, diabetes mellitus, dyslipidaemia and hypertension. The selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential for treating type 2 diabetes mellitus and metabolic syndrome. In the present study, we investigated the anti-diabetic and anti-adipogenic effects of 4-(2-(1,1-dioxido-6-(2,4,6-trichlorophenyl)-1,2,6-thiadiazinan-2-yl)acetamido)adamantane-1-carboxamide (KR-67183), a novel selective 11β-HSD1 inhibitor; we also investigated the underlying molecular mechanisms in the cortisone-induced 3T3-L1 adipogenesis model system and diet-induced obese (DIO) mice. KR-67183 concentration-dependently inhibited 11β-HSD1 activity in human and mouse 11β-HSD1 over-expressed cells and in the ex vivo assay of C57BL/6 mice. In the study with DIO mice, the administration of KR-67183 (20 and 50mg/kg/day, orally for 28 days) improved the glucose tolerance and insulin sensitivity with suppressed 11β-HSD1 activity in the liver and fat. However, KR-67183 showed no change in the adrenal gland weight/body weight ratio and plasma corticosterone concentration in DIO mice. Further, KR-67183 suppressed adipocyte differentiation on cortisone-induced adipogenesis in 3T3-L1 cells is associated with the suppression of the cortisone-induced mRNA levels of FABP4, PPARγ2 and GLUT4, and 11β-HSD1 activity. Taken together, it is suggested that a selective 11β-HSD1 inhibitor, KR-67183, may provide a new therapeutic window in the prevention and treatment without toxicity in type 2 diabetes with obesity.

Synthesis and 11β hydroxysteroid dehydrogenase 1 inhibition of thiazolidine derivatives with an adamantyl group.

A new series of thiazolidine derivatives with an adamantyl group was synthesized and evaluated for their ability to inhibit 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1). Our initial compound 5a showed a weak inhibitory activity. Significant improvements in potency were achieved by substituent modification. The potent compound 8g (E) showed good in vitro inhibitory activity toward human 11β-HSD1, selectivity toward 11β-HSD2, metabolic stability, pharmacokinetic, and safety profile. Furthermore, this compound significantly inhibited 11β-HSD1 activity in rat and monkey models, and showed improved glycemic control in KKAy mice.